Advancements and Challenges in Organic–Inorganic Composite Solid Electrolytes for All-Solid-State Lithium Batteries
全固态锂电池用有机-无机复合固体电解质的进展与挑战

Highlights 亮点

• The lithium-ion conduction mechanism of organic-inorganic composite solid electrolytes (OICSEs) is thoroughly conducted and concluded from the microscopic perspective based on filler content, type, and system.
  根据填料含量、类型和体系，从微观角度深入研究并总结了有机-无机复合固体电解质（OICSE）的锂离子传导机理。

• The classic inorganic filler types, including inert and active fillers, are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs.
  对传统的无机填料类型（包括惰性填料和活性填料）进行了分类，并特别强调了无机填料结构设计与 OICSE 电化学性能之间的关系。

• Advanced characterization techniques for OICSEs are discussed, and the challenges and prospects for developing superior all-solid-state lithium batteries are highlighted.
  讨论了 OICSE 的先进表征技术，并重点介绍了开发优质全固态锂电池所面临的挑战和前景。

Abstract 摘要

To address the limitations of contemporary lithium-ion batteries, particularly their low energy density and safety concerns, all-solid-state lithium batteries equipped with solid-state electrolytes have been identified as an up-and-coming alternative. Among the various SEs, organic–inorganic composite solid electrolytes (OICSEs) that combine the advantages of both polymer and inorganic materials demonstrate promising potential for large-scale applications. However, OICSEs still face many challenges in practical applications, such as low ionic conductivity and poor interfacial stability, which severely limit their applications. This review provides a comprehensive overview of recent research advancements in OICSEs. Specifically, the influence of inorganic fillers on the main functional parameters of OICSEs, including ionic conductivity, Li⁺ transfer number, mechanical strength, electrochemical stability, electronic conductivity, and thermal stability are systematically discussed. The lithium-ion conduction mechanism of OICSE is thoroughly analyzed and concluded from the microscopic perspective. Besides, the classic inorganic filler types, including both inert and active fillers, are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs. Finally, the advanced characterization techniques relevant to OICSEs are summarized, and the challenges and perspectives on the future development of OICSEs are also highlighted for constructing superior ASSLBs.
为了解决当代锂离子电池的局限性，特别是能量密度低和安全问题，配备固态电解质的全固态锂电池已被认为是一种新兴的替代技术。在各种固态电解质中，有机-无机复合固态电解质（OICSE）结合了聚合物和无机材料的优点，具有大规模应用的巨大潜力。然而，有机-无机复合固体电解质在实际应用中仍面临许多挑战，如离子电导率低、界面稳定性差等，严重限制了其应用。本综述全面概述了 OICSE 的最新研究进展。具体而言，系统讨论了无机填料对 OICSE 主要功能参数的影响，包括离子电导率、锂⁺ 转移数、机械强度、电化学稳定性、电子电导率和热稳定性。从微观角度深入分析和总结了 OICSE 的锂离子传导机理。此外，还对经典的无机填料类型（包括惰性填料和活性填料）进行了分类，并特别强调了无机填料结构设计与 OICSE 电化学性能之间的关系。最后，总结了与 OICSE 相关的先进表征技术，并强调了 OICSE 未来发展所面临的挑战和前景，以构建卓越的 ASSLB。

1 Introduction
1 简介

Rechargeable lithium-ion batteries (LIBs) are associated with significant safety concerns due to flammable and volatile organic liquid electrolytes, especially in large-scale energy storage applications such as electric vehicles and electronic devices [1,2,3,4,5]. In addition, the energy density of commercial lithium-ion batteries with liquid electrolyte and carbon-based anodes has reached 260 Wh kg⁻¹, which is close to their theoretical limitation [6,7,8]. All-solid-state lithium metal batteries (ASSLBs), with super-high theoretical energy density (> 300 Wh kg⁻¹) and excellent safety, have been widely recognized as one of the most promising next-generation battery technologies [9,10,11]. Solid-state electrolytes (SEs), as an important component of ASSLBs, have presented a rapidly increasing trend of investigations on SEs research in recent years [12,13,14,15].
可充电锂离子电池（LIB）因其易燃和易挥发的有机液态电解质而存在严重的安全问题，尤其是在电动汽车和电子设备等大规模储能应用中[1,2,3,4,5] 。此外，采用液态电解质和碳基阳极的商用锂离子电池的能量密度已达到 260 Wh kg^-1，接近其理论极限[6,7,8]。全固态锂金属电池（ASSLBs）具有超高的理论能量密度（> 300 Wh kg^-1）和出色的安全性，已被广泛认为是最有前途的下一代电池技术之一[9,10,11]。固态电解质（SEs）作为 ASSLBs 的重要组成部分，近年来在 SEs 研究方面呈现出快速增长的趋势 [12,13,14,15] 。

The physicochemical properties of the SEs, including interfacial reaction kinetics, safety, and durability, are critical to ASSLBs [16,17,18,19,20]. SEs can be divided into inorganic solid electrolytes (ISEs) and organic solid electrolytes (OSEs). ISEs exhibit high ionic conductivity (10⁻⁴–10⁻³ S cm⁻¹), Li⁺ transference number (~ 1), excellent thermal stability, and ultra-high mechanical strength [21, 22]. However, the inherent fragility and high hardness often result in poor interfacial wettability with both the cathode and anode and significantly increased processing challenges. Therefore, the practical application of ISEs still faces uncertainty [23,24,25]. By contrast, OSEs show higher feasibility with excellent elasticity, well flexibility, superior interface adhesion, and relatively high compatibility [26,27,28,29]. However, the polymer matrix with high crystallinity at room temperature (RT) always results in low ionic conductivity (10⁻⁷–10⁻⁵ S cm⁻¹), which is unfavorable for achieving high power density. Furthermore, the thermodynamic instability (oxidation potential less than 4 V vs. Li⁺/Li) restricts the matching with high-voltage cathode materials, while relatively inferior mechanical properties struggle to inhibit the lithium dendrite formation and growth [30,31,32]. In this situation, numerous strategies have been employed to enhance the overall performance of OSEs, such as block/cross-linked copolymerization, incorporation of plasticizers, and addition of inorganic fillers [33,34,35]. Among these approaches, the organic–inorganic composite solid electrolytes (OICSEs), which integrate the advantages of the organic polymer and inorganic fillers, are widely considered the most simple and feasible method to develop high-performance SEs for ASSLBs [36,37,38].
固态电解质的物理化学特性，包括界面反应动力学、安全性和耐久性，对 ASSLB 至关重要 [16,17,18,19,20] 。固态电解质可分为无机固态电解质（ISE）和有机固态电解质（OSE）。ISEs 具有高离子电导率（10^-4-10^-3 S cm^-1）、锂⁺ 转移数（~ 1）、优异的热稳定性和超高的机械强度[21, 22]。然而，其固有的脆性和高硬度往往导致与阴极和阳极的界面润湿性差，大大增加了加工难度。因此，ISE 的实际应用仍面临不确定性[23,24,25]。相比之下，OSE 具有优良的弹性、良好的柔韧性、优异的界面粘附性和相对较高的兼容性，显示出更高的可行性[26,27,28,29] 。然而，室温（RT）下结晶度高的聚合物基体总是导致离子电导率较低（10^-7-10^-5 S cm^-1），不利于实现高功率密度。此外，热力学不稳定性（对 Li⁺/Li 的氧化电位低于 4 V）限制了与高电压正极材料的匹配，而相对较差的机械性能也难以抑制锂枝晶的形成和生长 [30,31,32] 。 在这种情况下，人们采用了许多策略来提高 OSE 的整体性能，例如嵌段/交联共聚、加入增塑剂和无机填料[33,34,35]。在这些方法中，有机-无机复合固体电解质（OICSE）综合了有机聚合物和无机填料的优点，被广泛认为是为 ASSLB 开发高性能 SE 的最简单可行的方法[36,37,38]。

Generally, the inorganic materials can be divided into two categories: inert materials [39,40,41,42,43] (e.g., metal oxides (Al₂O₃, SiO₂, BaTiO₃, TiO₂, and MgO), halloysite nanotubes (HNTs), carbon materials (such as GO)), and active materials [44,45,46] (e.g., sulfide-type (Li₁₀GeP₂S₁₂ (LGPS)), garnet-type (Li₇La₃Zr₂O₁₂ (LLZO), and NASICON-type (Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP)), and perovskite-type (Li_0.33La_0.557TiO₃). It has been well confirmed that the functional mechanism of inorganic fillers can be summarized in the following three aspects [47,48,49]: (1) Inorganic fillers can improve the ratio of amorphous regions and enhance the mobility of local chain segments by disrupting the polymer crystallization behavior and reducing the glass transfer temperature (T_g). (2) The special functional groups on the surface of fillers can couple with lithium salt anions or polymer matrix via Lewis acid–base interactions, thereby facilitating the lithium ion transfer behaviors. Several factors, including size, type, concentration, morphology, and surface modifications of fillers, influence the strength of these interactions. (3) The inorganic fillers can increase the Li⁺ transfer number of OICSE and inhibit the enrichment of anions on the anode side, thus enhancing the electrochemical stability of OICSE. (4) Well-dispersed inorganic fillers can also improve the mechanical strength and thermal stability of OICSEs, effectively improving the reliability and security of the battery system. To improve the electrochemical performance of OICSEs, various inorganic fillers with different dimensions, such as 0D particles, 1D nanowires, 2D nanosheets, and 3D networks, have been specifically designed and widely investigated [50,51,52]. These fillers, exhibiting diverse morphologies, can provide long-range transport channels for lithium ions, resulting in a rapid ion transport pathway between the cathode and anode [53, 54]. Active fillers can directly participate in ion transport compared to inert fillers due to their intrinsic ionic conductivity. Meanwhile, a percolation pathway with fast ionic conductivity between active filler and polymer matrix can be constructed in the OICSEs, which is beneficial to improve the electrochemical performance of the battery system [55, 56].
一般来说，无机材料可分为两类：惰性材料[39,40,41,42,43] （如金属氧化物（Al₂O₃、SiO₂、BaTiO₃、TiO₂和 MgO）、和活性材料[44,45,46] (e. g.)g.,硫化物型（Li₁₀GeP₂S₁₂ (LGPS) ）、石榴石型（Li₇La₃Zr₂O₁₂ (LLZO) 和 NASICON 型（Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP))和透辉石型(Li_0.33La_0.557TiO₃)。经证实，无机填料的功能机理可归纳为以下三个方面[47,48,49] ：（1）无机填料可通过破坏聚合物结晶行为和降低玻璃转移温度（T_g）来提高无定形区的比例和增强局部链段的流动性。(2）填料表面的特殊官能团可通过路易斯酸碱相互作用与锂盐阴离子或聚合物基质耦合，从而促进锂离子转移行为。填料的尺寸、类型、浓度、形态和表面改性等多种因素都会影响这些相互作用的强度。 (3) 无机填料可以增加 OICSE 的锂⁺ 转移数，抑制阳极侧阴离子的富集，从而提高 OICSE 的电化学稳定性。(4) 充分分散的无机填料还能提高 OICSE 的机械强度和热稳定性，有效提高电池系统的可靠性和安全性。为了提高 OICSE 的电化学性能，人们专门设计并广泛研究了各种不同尺寸的无机填料，如 0D 颗粒、1D 纳米线、2D 纳米片和 3D 网络[50,51,52] 。这些形态各异的填料可为锂离子提供长距离传输通道，从而在阴极和阳极之间形成快速的离子传输途径[53, 54]。与惰性填料相比，活性填料因其固有的离子传导性可直接参与离子传输。同时，在 OICSE 中，活性填料和聚合物基质之间可以构建一条离子快速传导的渗流通道，这有利于提高电池系统的电化学性能[55, 56]。

Here, we emphasize the significance of various inorganic filler types and advanced structures in optimizing the performance of OICSEs (Fig. 1). Initially, key parameters such as ionic conductivity, Li⁺ transference number, mechanical properties, electrochemical stability, electronic conductivity, and thermal stability are extensively investigated. Subsequently, the impacts of the size, content, shape, and arrangement of inorganic fillers on ionic conductivity are analyzed. In addition, the lithium-ion conduction mechanism of OICSE is thoroughly conducted and concluded from the microscopic perspective based on filler content, type, and system. Furthermore, the classic inorganic filler types, including both inert and active fillers, are categorized. Special emphasis is placed on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs. Finally, Advanced characterization techniques for OICSEs like solid-state nuclear magnetic spectroscopy (NMR), magnetic resonance imaging (MRI), time-of-flight secondary ion mass spectrometry (TOF–SIMS), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS), small-angle X-ray scattering (SAXS), X-ray computed tomography (CT), and atomic force microscopy (AFM) are discussed, along with their applications and future challenges. The review concludes with a summary and perspective, offering valuable insights to facilitate the research and development of OICSEs with appreciable overall performance.
在此，我们强调各种无机填料类型和先进结构对优化 OICSE 性能的重要意义（图1）。首先，对离子电导率、锂⁺ 转移数、机械性能、电化学稳定性、电子电导率和热稳定性等关键参数进行了广泛研究。随后，分析了无机填料的大小、含量、形状和排列对离子导电率的影响。此外，根据填料的含量、类型和体系，从微观角度深入研究并总结了 OICSE 的锂离子传导机制。此外，还对经典的无机填料类型（包括惰性和活性填料）进行了分类。特别强调了无机填料结构设计与 OICSE 电化学性能之间的关系。最后，介绍了 OICSE 的先进表征技术，如固态核磁共振（NMR）、磁共振成像（MRI）、飞行时间二次离子质谱（TOF-SIMS）、高角度环形暗场扫描透射电子显微镜（HAADF-STEM）、电子能量损失光谱（EELS）、小角 X 射线散射（SAXS）、X 射线计算机断层扫描（CT）和原子力显微镜（AFM），以及它们的应用和未来挑战。综述最后进行了总结和展望，为促进具有可观整体性能的 OICSE 的研究和开发提供了宝贵的见解。

Fig. 1 图 1

Scope and content diagram are discussed in this review
本综述将讨论范围和内容图

2 Key Parameters to Evaluate the Performance of OICSEs
2 评估 OICSE 性能的关键参数

The ionic conductivity, Li⁺ transference number, mechanical properties, electrochemical stability, electronic conductivity, and thermal stability are essential indicators for evaluating the performance of OICSEs. A common problem of OSEs is low ionic conductivity and insufficient mechanical strength, which restricts their practical application in ASSLBs. To overcome these problems, researchers incorporate inorganic fillers into the polymer matrix. These fillers not only enhance the ionic conductivity but also improve the mechanical strength of the electrolytes, thereby optimizing the overall electrochemical performance of OICSEs in ASSLBs.
离子电导率、Li⁺ 传递数、机械性能、电化学稳定性、电子电导率和热稳定性是评价 OICSE 性能的重要指标。OICSE 的一个常见问题是离子导电率低和机械强度不足，这限制了其在 ASSLB 中的实际应用。为了克服这些问题，研究人员在聚合物基体中加入了无机填料。这些填料不仅增强了离子导电性，还提高了电解质的机械强度，从而优化了 ASSLB 中 OICSE 的整体电化学性能。

2.1 Ionic Conductivity
2.1 离子电导率

2.1.1 Effects of Inorganic Fillers on Ionic Conductivity
2.1.1无机填料对离子传导性的影响

(a) Particle Size and Content: The inorganic particle size and content are key factors to improve the ionic conductivity of the OICSEs [57,58,59]. Dissanayake et al. evaluated the thermal and electrical properties of the (PEO)₉LiCF₃SO₃-Al₂O₃ incorporating alumina filler grains with different specific surface areas [60]. The results indicate that the nano-porous alumina grains with 5.8 nm pore size and 150 m² g⁻¹ specific area and 15 wt% filler exhibited the maximum ionic conductivity, which is attributed to Lewis acid–base interactions of ionic species with O/OH groups on the filler surface. Generally, incorporating 10–20 wt% of ceramic filler into the polymer matrix is considered the optimal concentration for OICSEs. The particles tend to undergo agglomeration behavior with the increase of content, reducing the volume fraction and disrupting the percolation network at the interface. Zhang et al. investigated that Li-salt-free PEO and LLZTO nanoparticles in size of D₅₀ = 43 nm show the highest ionic conductivity of 2.1 × 10⁻⁴ S cm⁻¹ at 30 °C [61], which is nearly two orders of magnitude higher than that of micron-sized LLZTO fillers (Fig. 2a). When the LLZTO size is fixed at 43 nm, and content is 12.7 vol% within different temperature ranges (Fig. 2b), the PEO:12.7 vol% LLZTO membrane achieved the maximum ionic conductivity. Moreover, the result found that as the size of LLZTO particles increased from 40 to 400 nm and 10 mm, the optimal ceramic content also increased from 12.7 to 15.1 vol% and 21.1 vol%, respectively (Fig. 2c). Therefore, it can be concluded that the particle size is related to the percolation of LLZTO particles, and the percolation threshold decreases with the decrease in particle size [62]. Nanoparticles have a larger specific surface area and can increase the area of the polymer electrolyte/filler interface, providing more ion transport pathways, thus significantly increasing the ionic conductivity of the OICSEs [63]. Therefore, nanoparticles are more effective in improving ionic conductivity than micron-sized particles.
(a) 粒径和含量：无机颗粒的粒径和含量是提高 OICSE 离子电导率的关键因素[57,58,59] 。Dissanayake 等人评估了（PEO）₉LiCF₃SO₃-Al₂O₃ 含有不同比表面积的氧化铝填料颗粒[60]。结果表明，孔径为 5.8 nm、比表面积为 150 m² g^-1 且填料含量为 15 wt%的纳米多孔氧化铝颗粒具有最大的离子导电性，这归因于离子物种与填料表面 O/OH 基团的路易斯酸碱相互作用。一般来说，在聚合物基体中加入 10-20 wt%的陶瓷填料被认为是 OICSE 的最佳浓度。随着含量的增加，颗粒往往会发生团聚行为，从而降低体积分数并破坏界面处的渗滤网络。Zhang 等人研究发现，尺寸为 D₅₀ = 43 nm 的无锂盐 PEO 和 LLZTO 纳米粒子显示出最高的离子电导率（2.1 × 10^-4 S cm^-1 ，温度为 30 °C [61]，比微米尺寸的 LLZTO 填料高出近两个数量级（图2a）。在不同温度范围内，当 LLZTO 尺寸固定为 43 nm，含量为 12.7 vol% 时（图 2b），PEO:12.A 的温度范围为 0.5 °C（图 2c）。7 Vol% 的 LLZTO 膜实现了最大离子导电率。此外，结果还发现，随着 LLZTO 颗粒尺寸从 40 纳米增加到 400 纳米和 10 毫米，最佳陶瓷含量也分别从 12.7% 和 21.1% 增加到 15.1 vol%（图 2c ）。因此，可以得出结论：粒径与 LLZTO 粒子的渗滤有关，渗滤阈值随着粒径的减小而降低[62]。纳米粒子具有更大的比表面积，可以增加聚合物电解质/填料界面的面积，提供更多的离子传输途径，从而显著提高 OICSE 的离子电导率[63]。因此，在提高离子传导性方面，纳米颗粒比微米大小的颗粒更有效。

Fig. 2 图 2

a Size distribution of LLZTO nanoparticles determined by a laser particle size analyzer. b Ion conductivities of PEO: LLZTO membranes with different volume fractions of LLZTO in size of D₅₀ = 43 nm. c Ionic conductivity as a function of LLZTO volume fraction for LLZTO particles with different sizes [61], Copyright 2016, Elsevier. d Ion conductivities of PAN/LiClO₄, PAN/LiClO₄ with LLTO nanowires, and LLTO nanoparticles and the comparison of possible lithium-ion conduction pathway in nanowire-filled and nanoparticle-filled composite electrolytes [64], Copyright 2015, American Chemical Society. e Schematic diagram of garnet nanosheets and comparing composite electrolytes consisting of garnet nanoparticles [66], Copyright 2019, American Chemical Society. f Li-ion conduction pathways in OICSEs with nanoparticles, random nanowires, and aligned nanowires [67], Copyright 2017, Springer Nature Limited. g Ionic conductivity of vertically aligned, random, and polymer [68], Copyright 2017, American Chemical Society. h Schematics of agglomerated nanoparticles and 3D continuous framework. i Ionic conductivity of LLTO framework, LLTO nanoparticle, and silica particle OICSEs [69], Copyright 2018 Wiley
a 激光粒度分析仪测定的 LLZTO 纳米粒子的粒度分布。b PEO：尺寸为 D₅₀ = 43 nm 的不同 LLZTO 体积分数的 PEO: LLZTO 膜的离子传导率。c 不同尺寸 LLZTO 颗粒的离子电导率与 LLZTO 体积分数的函数关系 [61]，爱思唯尔版权所有，2016 年。d 含有 LLTO 纳米线的 PAN/LiClO₄, PAN/LiClO₄ 的离子电导率、和 LLTO 纳米粒子以及纳米线填充和纳米粒子填充复合电解质中可能的锂离子传导途径的比较[64]，美国化学学会版权所有，2015 年。e石榴石纳米片和石榴石纳米颗粒组成的复合电解质比较示意图[66]，版权所有，美国化学会，2019 年。f 具有纳米颗粒、随机纳米线和排列纳米线的 OICSE 中的锂离子传导路径 [67]，版权归 Springer Nature Limited 2017 所有。g 垂直排列、随机和聚合物的离子电导率 [68], Copyright 2017, 美国化学学会。h 团聚纳米粒子和三维连续框架示意图。i LLTO 框架、LLTO 纳米粒子和二氧化硅粒子 OICSE 的离子电导率 [69]，2018 年威利版权所有。

(b) Shape of Inorganic Fillers: The ion conduction mechanism based on the percolation effect has shown that the development of specially shaped ceramic fillers (nanowire fillers) can effectively improve the uniform transport of lithium ions and avoid the decrease of ionic conductivity caused by the agglomeration of fillers. Liu et al. explored the impact of nanoparticles and nanowires on the electrochemical performance of PAN/LiClO₄ polymer electrolytes [64]. The 15 wt% LLTO nanowires would increase the ionic conductivity by three orders of magnitude over the same content of LLTO nanoparticles. This is mainly because LLTO nanowires create a longer distance than nanoparticles for the ion transport pathway (Fig. 2d). To improve the transport pathway of LLTO nanoparticles in the polymer matrix, Fu et al. reported a 3D garnet nanofiber network by electrostatic spinning and high-temperature annealing with an ionic conductivity of 2.5 × 10⁻⁴ S cm⁻¹ at RT, two orders of magnitude higher than that of PEO-based electrolyte containing LLZO nanoparticles [65]. The increased conductivity can be attributed to the 3D interconnected structure, which offers a continuous transport pathway for Li ions. Compared to nanoparticles, garnet nanosheets also have interconnected Li ion transport pathways. Song et al. introduced 15 wt% garnet nanosheets into the polymer matrix for the first time, the ionic conductivity achieved was 3.6 × 10⁻⁴ S cm⁻¹ at RT (Fig. 2e) [66]. Therefore, introducing nanowires and nanosheets into the polymer matrix or constructing a three-dimensional or two-dimensional interconnection network structure can provide a continuous Li-ion transport pathway, thereby obtaining higher ionic conductivity.
（b）无机填料的形状：基于渗流效应的离子传导机理表明，开发特殊形状的陶瓷填料（纳米线填料）可有效改善锂离子的均匀传输，避免填料团聚导致的离子传导率下降。Liu 等人探讨了纳米颗粒和纳米线对 PAN/LiClO₄ 聚合物电解质电化学性能的影响[64]。与相同含量的 LLTO 纳米粒子相比，15 wt% 的 LLTO 纳米线可将离子电导率提高三个数量级。这主要是因为 LLTO 纳米线的离子传输路径比纳米粒子长（图2d）。为了改善 LLTO 纳米粒子在聚合物基体中的传输途径，Fu 等人报道了一种通过静电纺丝和高温退火制备的三维石榴石纳米纤维网络，其离子电导率为 2.5 × 10^-4 S cm^-1 ，比含有 LLZO 纳米粒子的 PEO 基电解质高两个数量级 [65] 。电导率的提高可归因于三维互连结构为锂离子提供了连续的传输途径。与纳米颗粒相比，石榴石纳米片也具有相互连接的锂离子传输途径。Song 等人首次在聚合物基体中引入了 15 wt% 的石榴石纳米片，在 RT 条件下，离子电导率达到了 3.6 × 10^-4 S cm^-1 （图 2e) [66]。 因此，在聚合物基体中引入纳米线和纳米片，或构建三维或二维互连网络结构，可以提供连续的锂离子传输途径，从而获得更高的离子导电性。

(c) Arrangement of Inorganic Fillers: To reduce the tortuosity of ion conduction pathway in OICSEs and to obtain larger inorganic particle/polymer interfaces, researchers have employed various methods to create OICSEs with oriented ceramic fillers, including electrostatic spinning, ice-templating-based methods, and 3D printing techniques. Liu and colleagues have developed well-oriented LLTO nanowires by electrospinning and embedding the LLTO nanowires in the PAN-LiClO₄ electrolyte (Fig. 2f) [67]. This innovative design has resulted in a remarkable ionic conductivity of 6.05 × 10⁻⁵ S cm⁻¹ at 30 °C, ten orders of magnitude higher than previous polymer electrolytes containing randomly arranged nanowires. The exceptional conductivity improvement is attributed to the efficient ion-conducting pathway created by the aligned nanowires. A flexible OICSE composed of vertically aligned and connected LATP NPs has been synthesized through the ice-templating process (Fig. 2g) [68]. The alignment of the nanoparticles creates direct channels for lithium ions, and the OICSEs show an impressive ionic conductivity of 0.52 × 10⁻⁴ S cm⁻¹ at RT, which is 3.6 orders of magnitude higher than the PEO electrolyte containing LATP NPs randomly dispersed within the material. It has been discovered that 3D ceramic frameworks can significantly enhance the continuous and integrated ion-conduction network and increase mechanical strength. Bae and colleagues proposed a 3D hydrogel-derived nanostructured LLTO framework as a highly loaded nanofiller (Fig. 2h) [69]. The interconnected structure of the 3D LLTO framework provides a long-range, continuous pathway for Li-ions, which results in an impressive ionic conductivity of 8.8 × 10⁻⁵ S cm⁻¹ at RT (Fig. 2i). Although OICSEs exhibit enhanced ionic conductivity, the polymer matrix limits the overall ionic conductivity. There are still many challenges to achieving practical applications at RT. Therefore, we need to improve the ionic conductivity further by designing the ceramic structure and optimizing the polymer matrix composition.
（c）无机填料的排列：为了减少 OICSE 中离子传导路径的曲折性并获得更大的无机颗粒/聚合物界面，研究人员采用了各种方法来制造具有取向陶瓷填料的 OICSE，包括静电纺丝、基于冰模板的方法和三维打印技术。Liu 及其同事通过电纺丝将 LLTO 纳米线嵌入 PAN-LiClO₄ 电解质（图2f），开发出了取向良好的 LLTO 纳米线[67]。通过这种创新设计，30 °C 时的离子电导率达到 6.05 × 10^-5 S cm^-1 ，比以前含有随机排列纳米线的聚合物电解质高出十个数量级。电导率的显著提高归功于排列整齐的纳米线所形成的高效离子传导通路。通过制冰工艺合成了由垂直排列和连接的 LATP NPs 组成的柔性 OICSE（图2g）[68]。纳米粒子的排列为锂离子创建了直接通道，OICSE 在 RT 时显示出 0.52 × 10^-4 S cm^-1 的惊人离子电导率，比随机分散在材料中含有 LATP NP 的 PEO 电解质高出 3.6 个数量级。研究发现，三维陶瓷框架可显著增强连续、集成的离子传导网络，并提高机械强度。Bae 及其同事提出了一种三维水凝胶衍生纳米结构 LLTO 框架作为高负载纳米填料（图 6）。2h）[69]。三维 LLTO 框架的相互连接结构为锂离子提供了一个长程、连续的通路，从而在 RT 条件下实现了 8.8 × 10^-5 S cm^-1 的惊人离子电导率（图2i）。虽然 OICSE 显示出更强的离子传导性，但聚合物基质限制了整体离子传导性。在 RT 条件下实现实际应用仍面临许多挑战。因此，我们需要通过设计陶瓷结构和优化聚合物基质成分来进一步提高离子电导率。

2.2 Mechanical Properties
2.2 机械特性

Mechanical properties are the physical characteristics of a material that it exhibits under the action of various forces, including toughness, hardness, strength, brittleness, and elasticity. Good mechanical properties can effectively hinder the formation and growth of lithium dendrites, which contribute to long cycling life [70]. Inorganic fillers in composite electrolytes usually have adequate strength but lack flexibility. The addition of inorganic fillers increases tensile strength but decreases elongation at break compared to the polymer matrix. For example, the addition of 5 wt% carbon nanotubes to the PEO polymer matrix can increase tensile strength by 160%, improving the mechanical properties of OICSEs significantly [71]. However, due to the presence of inorganic fillers, the polymer flexibility and adhesion in OICSEs decreases, which affects close contact with the electrodes and leads to an increase in interfacial resistance during cycling. Therefore, the balance between mechanical properties and interface contact with the electrode is required when designing OICSEs. The thickness of OICSEs is indeed crucial for the development of high-energy solid-state batteries. Currently, the thickness of the prepared OICSEs membranes is much thicker than that of commercial membranes, and most of the OICSEs are about 100 μm or thicker. It remains challenging to prepare OICSEs using traditional methods that maintain excellent mechanical properties while being ultrathin. Luo et al. [72] prepared ultrathin (4.2 μm) CSEs with a bilayer polymer structure (UFF/PEO/PAN/LiTFSI) by electrospinning, and the hard UFF ceramic scaffolds can maintain the mechanical strength. The elastic moduli of the PEO and PAN sides were measured by nanoindentation to be 298 and 1072 MPa, respectively. The high energy density of 506 Wh kg⁻¹ and 1514 Wh L⁻¹ is achieved based on LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathodes with a low N/P ratio and long lifespan over 3000 h. Wang et al. [73] fabricated LLZO layer and metal–organic framework (MOF) layer on both sides of polyethylene (PE) by tape casting and developed an ultrathin (12.6 μm) asymmetric composite solid electrolyte. The Li-symmetric battery has an ultra-long cycle (5000 h) and the assembled pouch cells provided a gravimetric/ volume energy density of 344.0 Wh kg⁻¹/773.1 Wh L⁻¹. However, it should be noted that OICEs inevitably reduce mechanical strength and increase the risk of membrane rupture or lithium dendrite growth, leading to interruption of ionic conduction and cell failure. Meanwhile, excessive hardness or elastic modulus may increase the impedance at the electrode–electrolyte interface, affecting the energy density and power density of the battery. Therefore, when designing and optimizing OICSEs, the above mechanical properties need to be considered to achieve excellent electrochemical performance and long-life battery systems.
机械性能是指材料在各种力的作用下所表现出的物理特性，包括韧性、硬度、强度、脆性和弹性。良好的机械性能可有效阻碍锂枝晶的形成和生长，从而延长循环寿命[70]。复合电解质中的无机填料通常具有足够的强度，但缺乏柔韧性。与聚合物基体相比，添加无机填料可增加拉伸强度，但会降低断裂伸长率。例如，在 PEO 聚合物基体中添加 5 wt% 的碳纳米管可将拉伸强度提高 160%，从而显著改善 OICSE 的机械性能 [71]。但是，由于无机填料的存在，OICSE 中聚合物的柔韧性和粘附性降低，从而影响了与电极的紧密接触，导致循环过程中界面电阻增加。因此，在设计 OICSE 时，需要在机械性能和与电极的界面接触之间取得平衡。事实上，OICSE 的厚度对于高能固态电池的开发至关重要。目前，制备的 OICSE 膜的厚度比商业膜厚得多，大多数 OICSE 的厚度约为 100 μm 或更厚。使用传统方法制备 OICSE，既要保持优异的机械性能，又要达到超薄的效果，这仍然是一项挑战。Luo 等人[72]通过电纺丝法制备了具有双层聚合物结构（UFF/PEO/PAN/LiTFSI）的超薄（4.2 μm）CSE，坚硬的 UFF 陶瓷支架能保持机械强度。 通过纳米压痕测量，PEO 和 PAN 两侧的弹性模量分别为 298 和 1072 兆帕。基于 LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811)阴极实现了低 N/P 比和超过 3000 小时的长寿命。Wang等人[73]通过胶带浇注法在聚乙烯（PE）双面制备了LLZO层和金属有机框架（MOF）层，并开发了一种超薄（12.6 μm）不对称复合固体电解质。这种锂对称电池具有超长的循环周期（5000 小时），组装后的袋装电池的重量/体积能量密度为 344.0 Wh kg^-1/773.1 Wh L^-1 。但需要注意的是，OICE 不可避免地会降低机械强度，增加膜破裂或锂枝晶生长的风险，导致离子传导中断和细胞失效。同时，过高的硬度或弹性模量可能会增加电极-电解质界面的阻抗，影响电池的能量密度和功率密度。因此，在设计和优化 OICSE 时，需要考虑上述机械性能，以实现优异的电化学性能和长寿命电池系统。

Generally, the mechanical strength is described by the equations of Young's modulus of elasticity (E, MPa) and shear modulus (G, MPa). The specific equations are as follows [74, 75]:
一般来说，机械强度由杨氏弹性模量（E，兆帕）和剪切模量（G，兆帕）方程描述。具体公式如下 [74, 75]：

$$E={\text{V}\text{ι}}^2\rho \frac{\left(1+\text{ν}\right)\left(1-2\text{υ}\right)}{\left(1-\text{ν}\right)}$$

(1)

$$G=\frac{\text{E}}{2\left(1+\text{ν}\right)}$$

(2)

where $\text{ρ}$ is the density, $\text{V}\text{ι}$ is the longitudinal velocity, and $\text{ν}$ is Poisson’s ratio, ν = 0.257 [76]. In addition to Young's modulus and shear modulus, other parameters such as maximum stress (MPa) and strain at break (mm/mm) are also helpful in describing the mechanical properties of OICSEs in ASSLBs.
其中 $\text{ρ}$ 是密度，$\text{V}\text{ι}$ 是纵向速度，$\text{ν}$ 是泊松比，ν = 0。257 [76]。除了杨氏模量和剪切模量，最大应力（兆帕）和断裂应变（毫米/毫米）等其他参数也有助于描述 ASSLB 中 OICSE 的机械性能。

2.3 Li-Ion Transference Number
2.3锂离子转移数

Li-ion transference number is another important parameter to evaluate the electrochemical performance of OICSEs, which is the contribution of Li-ion transport charge to the total charge, calculated as the ratio of Li-ionic conductivity to total ionic conductivity. In OICSEs, which consist of multiple ions and are referred to as multi-ion conductors, the ionic conductivity is influenced by both Li-ion and anion transport. Lithium ions and anions can move during cycling but move in opposite directions. Consequently, a significant Li-ion concentration gradient is formed from the anode to the cathode, impeding Li-ion transport and resulting in undesired Li deposition. The Li-ion migration number of OICSEs can be obtained by the DC/AC electrochemical method proposed by Bruce [77, 78]. By assembling a Li |OICSEs| Li symmetric cell, an impedance spectrum test is performed before polarization begins, and then a minimal potential is applied for polarization tests, where the Li ions and anions move in opposite directions in response to an electric field. The lithium ions are reduced to Li atoms at the electrode interface, while the anions accumulated at the interface do not participate in the electrochemical reaction. Meanwhile, the anions can diffuse to the low potential electrode under concentration polarization. Finally, the impedance of the symmetric cell is tested after polarization. Based on the impedance change and current response, the Li⁺ migration number can be obtained using Eq. (3):
锂离子传输数是评估 OICSE 电化学性能的另一个重要参数，它是锂离子传输电荷对总电荷的贡献，计算方法是锂离子电导率与总离子电导率之比。OICSE 由多种离子组成，被称为多离子导体，其离子电导率受锂离子和阴离子传输的影响。锂离子和阴离子可在循环过程中移动，但移动方向相反。因此，从阳极到阴极会形成明显的锂离子浓度梯度，阻碍锂离子迁移，导致锂沉积。OICSE 的锂离子迁移数可通过 Bruce [77, 78] 提出的 DC/AC 电化学方法获得。通过组装一个锂|OICSEs|锂对称电池，在极化开始前进行阻抗谱测试，然后施加最小电位进行极化测试，锂离子和阴离子在电场的作用下向相反的方向移动。锂离子在电极界面上还原成锂原子，而积聚在界面上的阴离子则不参与电化学反应。同时，阴离子可在浓度极化作用下扩散到低电位电极。最后，测试极化后对称电池的阻抗。根据阻抗变化和电流响应，可利用公式（3）求出锂⁺ 迁移数：

$$t_{L{i}^{+}}=\frac{I_s\left(\mathrm{\Delta }\text{V}-I_0{R}_0\right)}{I_0\left(\mathrm{\Delta }\text{V}-I_s{R}_s\right)}$$

(3)

where $\mathrm{\Delta }\text{V}$ is the dc polarization voltage, $I_0$ and $I_s$ are the initial and steady-state current, respectively. The $R_0$ and $R_s$ are the initial and steady-state interfacial impedance, respectively. Most OSEs are multi-ion conductors, so the Li-ion transference number of OSEs is generally low, usually only about 0.1–0.2 [79]. In contrast, ISEs are typically single Li-ion conductors with a migration number roughly equal to 1. Therefore, the ion migration number of composite ion conductors is generally more significant than that of OSEs.
其中 $\mathrm{\Delta }\text{V}$ 是直流极化电压，$I_0$ 和 $I_s$ 分别是初始电流和稳态电流。$R_0$ 和 $R_s$ 分别是初始和稳态界面阻抗。大多数 OSE 都是多离子导体，因此 OSE 的锂离子转移数通常很低，通常只有约 0.1-0.2 [79]。因此，复合离子导体的离子迁移数通常比 OSE 的离子迁移数更为显著。

2.4 Electrochemical Stability
2.4 电化学稳定性

The electrochemical window is a vital parameter in evaluating the electrochemical stability of solid-state electrolytes. It determines the range of feasible reversible electrochemical reactions, facilitating controlled electrode potential during electrochemical desorption and adsorption processes and preventing irreversible reactions. The electrochemical window is typically measured by cyclic voltammetry or linear scanning voltammetry, using electrochemical cells containing working and reference electrodes for the configuration. The electrochemical window directly affects the lifetime and performance of the cell. Expanding the electrochemical window can enhance the compatibility of the solid-state electrolyte with both positive and negative electrodes, reduce energy losses and electrolyte degradation, and improve battery capacity retention and cycling stability. Generally, OICSEs offer a wider electrochemical window compared to OSEs. This phenomenon arises from the propensity of the polymer matrix in OSEs to decompose at high voltages, limiting their electrochemical window [80]. The most common oxidize potential of PEO-based polymer electrolytes is about 3.8 V, limiting their application in high energy density battery systems. Zhang et al. [81] developed an anion-immobilized OICSE to protect Li metal anodes by adding 40 wt% LLZTO to PEO (LiTFSI) polymer matrix. Compared to conventional liquid electrolytes with mobile anions, inorganic fillers effectively immobilize anions, resulting in uniform ion distribution and no dendritic lithium deposition. The wide electrochemical window (5.5 V vs. Li⁺/Li) of OICSE without distinct reaction was measured by LSV using Li|OICSE|SS. This indicates that OICSE has good polarization tolerance and great potential for high-voltage lithium batteries. The improvement of the OICSE electrochemical window is due to the excellent stability of LLZTO and its surface passivation layer towards lithium metal, while finely dispersed ceramic fillers help to remove impurities at the interface. Ding et al.[82] reported the addition of boron nitride (BN) to the PEO-LiTFSI system, BN reduces the crystallinity of PEO, promotes the dissociation of LiTFSI, and improves the ability of the PEO chain segment to transport ions, and the electrochemical stabilization window is increased from 4.43 to 5.16 V versus Li⁺/Li based on Li|OICSE|SS cell. The improvement in the electrochemical window is due to stronger binding between TFSI⁻¹ and BN, which inhibits TFSI⁻¹ transport and promotes Li⁺ transport. This slows down the concentration gradient and polarization and improves the stability of the lithium electrodeposition. Zhang et al. [83] prepared a flexible PEO/PEG-3LGPS composite electrolyte through an in situ coupling reaction, in which the ceramic and polymer were tightly bound to each other by strong chemical bonding, and successfully solved the interfacial compatibility problem. The oxidation potential of this PEO/PEG-3LGPS composite electrolyte was increased to 5.1 V versus Li⁺/Li based on Li|OICSE|SS cell. The enhancement of the electrochemical window was attributed to the higher ionic conductivity reducing the Li⁺ accumulation at the electrode/electrolyte interface, thus lowering the interfacial over-potential, and ultimately achieving better electrode–electrolyte compatibility.
电化学窗口是评估固态电解质电化学稳定性的一个重要参数。它决定了可行的可逆电化学反应的范围，有利于在电化学解吸和吸附过程中控制电极电位，并防止不可逆反应的发生。电化学窗口通常通过循环伏安法或线性扫描伏安法测量，使用的电化学电池包含工作电极和参比电极。电化学窗口直接影响电池的寿命和性能。扩大电化学窗口可增强固态电解质与正负电极的兼容性，减少能量损失和电解质降解，提高电池容量保持率和循环稳定性。一般来说，与 OSE 相比，OICSE 具有更宽的电化学窗口。这种现象是由于 OSE 中的聚合物基质在高电压下容易分解，从而限制了其电化学窗口[80]。基于 PEO 的聚合物电解质最常见的氧化电位约为 3.8 V，这限制了它们在高能量密度电池系统中的应用。Zhang 等人[81]在 PEO（LiTFSI）聚合物基质中加入 40 wt% 的 LLZTO，开发出一种阴离子固定的 OICSE，用于保护锂金属阳极。与具有流动阴离子的传统液态电解质相比，无机填料能有效固定阴离子，从而使离子分布均匀，不会出现树枝状锂沉积。通过使用 Li|OICSE|SS 进行 LSV 测量，OICSE 具有较宽的电化学窗口（5.5 V vs. Li⁺/Li ），且无明显反应。 这表明 OICSE 具有良好的极化耐受性，在高压锂电池方面具有巨大潜力。OICSE 电化学窗口的改善得益于 LLZTO 及其表面钝化层对锂金属的优异稳定性，而精细分散的陶瓷填料有助于去除界面上的杂质。Ding 等人[82]报道了在 PEO-LiTFSI 体系中加入氮化硼（BN），BN 降低了 PEO 的结晶度，促进了 LiTFSI 的解离，提高了 PEO 链段传输离子的能力，电化学稳定窗口从 4.基于 Li|OICSE|SS 电池，与 Li⁺/Li 相比，电化学稳定窗口从 4.43 V 提高到 5.16 V。电化学窗口的改善是由于 TFSI^-1 和 BN 之间的结合力更强，从而抑制了 TFSI^-1 的传输，促进了 Li⁺ 的传输。这减缓了浓度梯度和极化，提高了锂电沉积的稳定性。Zhang等人[83]通过原位偶联反应制备了柔性PEO/PEG-3LGPS复合电解质，陶瓷和聚合物之间通过强化学键紧密结合，成功解决了界面相容性问题。基于 Li|OICSE|SS 电池，这种 PEO/PEG-3LGPS 复合电解质对 Li⁺/Li 的氧化电位提高到了 5.1 V。 电化学窗口的增强归因于较高的离子电导率减少了电极/电解质界面上的锂⁺ 积累，从而降低了界面过电位，最终实现了更好的电极-电解质兼容性。

2.5 Electronic Conductivity
2.5电子导电率

Electronic conductivity is often considered another key criterion for ASSLBs applications. Ideally, the electronic conductivity of a composite electrolyte should be as close to zero as possible, typically in the range of 10⁻¹⁰ S cm⁻¹ or less. A recent study shows that the high electronic conductivity of solid electrolytes allows Li⁺ to combine with electrons to form lithium dendrites directly inside these SEs when the potential reaches the Li plating potential. Wang et al. [84] investigated the formation mechanism of dendritic grains in LLZO and Li₃PS₄ using operational neutron depth profiling (NDP), emphasizing the important role of reducing the electronic conductivity of SEs to achieve dendrite-free lithium plating at high current densities. Polymers typically have lower electronic conductivity (10⁻¹⁴ and 10⁻¹⁷ S cm⁻¹) compared to inorganic materials. Therefore, the reduction of the electronic conductivity of electrolytes is favored by inorganic–organic composites. Goodenough et al. reported that CPE-25LZP has a low electronic conductivity of 9.0 × 10^–10 S cm⁻¹ at 25 °C [85]. Low electronic conductivity ensures that the electrolyte conducts ions rather than electrons, which avoids self-discharge and internal short-circuit problems in batteries.
电子电导率通常被视为 ASSLB 应用的另一个关键标准。理想情况下，复合电解质的电子电导率应尽可能接近于零，通常在 10^-10 S cm^-1 或更低的范围内。最近的一项研究表明，固体电解质的高电子传导性允许锂⁺ 在电位达到锂电镀电位时与电子结合，直接在这些固体电解质内部形成锂枝晶。Wang 等人[84]利用操作中子深度剖析（NDP）研究了 LLZO 和 Li₃PS₄ 中树枝状晶粒的形成机制，强调了降低 SE 的电子电导率对于在高电流密度下实现无树枝状锂电镀的重要作用。与无机材料相比，聚合物的电子电导率通常较低（10^-14 和 10^-17 S cm^-1 ）。因此，无机-有机复合材料有利于降低电解质的电子电导率。Goodenough 等人报告说，CPE-25LZP 的电子电导率较低，在 25 °C 时为 9.0 × 10^-10 S cm^-1 [85]。低电子电导率可确保电解质传导离子而非电子，从而避免电池自放电和内部短路问题。

2.6 Thermal Stability
2.6热稳定性

High thermal stability prevents OICSEs from decomposing during the thermal runaway of the battery, which plays a critical role in the safety of ASSLBs. Currently, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are commonly used techniques to analyze these properties. The thermal decomposition temperature and mass loss of the composite electrolyte can be measured by TGA, while the thermal stability and phase transition temperature of the material can be analyzed by DSC. Most inorganic electrolytes have high decomposition temperatures, so the addition of inorganic materials to OICSEs can improve the thermal stability of the electrolytes. For example, Ramaswamy et al. [86] investigated the thermogravimetric analysis curves of PVDF-HFP/POEGMA/LLZTO composite electrolytes by TG. The results showed that the weight of PVDF-HFP/POEGMA gradually decreased by about 25% from 240 to 395 °C for the membrane without LLZTO, while the weight of PVDF-HFP/POEGMA/LLZTO only gradually decreased from 245 to 420 °C, indicating that the incorporation of LLZTO filler improved the thermal stability. Meanwhile, the thermal stability of ASSLBs can be improved by introducing inorganic fillers. Cui et al. [87] reported a poly(propylene carbonate) (PPC) and 5 wt% LLZTO CSE. Commercial lithium-ion batteries using organic liquid electrolytes typically suffer severe performance degradation when operating temperatures exceed 60 °C. The solid-state battery of LiFePO₄||Li based on the OICSE was operated at 160 °C with excellent rate capability at high rates, indicating that the OICSE can be used in the field of high-temperature lithium batteries. The melting point (T_m), glass transition temperature (T_g), and crystallinity (X_c) can be obtained by DSC testing. The effect of SN plasticizer on the thermal properties of the PEO-LLZTO composite electrolyte was investigated [88]. The T_g, T_m, and X_c of the composite electrolyte gradually decreased with the addition of SN, when the content of SN was increased to 60 wt%, and the composite electrolyte with the highest ionic conductivity was obtained. Although plasticizers can improve the ionic conductivity of OICSEs by reducing polymer crystallization, they can also reduce the mechanical strength and the safety of ASSLBs, requiring a comprehensive consideration of the amount used.
高热稳定性可防止 OICSE 在电池热失控过程中分解，这对 ASSLB 的安全性起着至关重要的作用。目前，热重分析（TGA）和差示扫描量热法（DSC）是分析这些特性的常用技术。TGA 可以测量复合电解质的热分解温度和质量损失，而 DSC 可以分析材料的热稳定性和相变温度。大多数无机电解质的分解温度较高，因此在 OICSE 中添加无机材料可以提高电解质的热稳定性。例如，Ramaswamy 等人 [86] 通过 TG 研究了 PVDF-HFP/POEGMA/LLZTO 复合电解质的热重分析曲线。结果表明，在不含 LLZTO 的膜中，PVDF-HFP/POEGMA 的重量从 240 ℃ 到 395 ℃ 逐渐减少约 25%，而 PVDF-HFP/POEGMA/LLZTO 的重量仅从 245 ℃ 到 420 ℃ 逐渐减少，这表明 LLZTO 填料的加入提高了热稳定性。同时，通过引入无机填料也可以提高 ASSLB 的热稳定性。Cui 等人[87]报道了一种聚（碳酸丙烯酯）（PPC）和 5 wt% LLZTO CSE。当工作温度超过 60 °C 时，使用有机液态电解质的商用锂离子电池通常会出现严重的性能下降。基于 OICSE 的 LiFePO₄||Li 固态电池在 160 ℃ 下运行，在高倍率下具有出色的速率能力，这表明 OICSE 可用于高温锂电池领域。 通过 DSC 测试可获得熔点（T_m）、玻璃化转变温度（T_g）和结晶度（X_c）。研究了 SN 增塑剂对 PEO-LLZTO 复合电解质热性能的影响 [88]。当 SN 的含量增加到 60 wt%时，复合电解质的 T_g、T_m和 X_c 随着 SN 的添加而逐渐降低，并得到了离子电导率最高的复合电解质。虽然增塑剂可以通过减少聚合物结晶来提高 OICSE 的离子导电率，但同时也会降低 ASSLB 的机械强度和安全性，因此需要综合考虑使用量。

3 Mechanism of Li-Ion Transport in OICSEs
3 OICSE 中的锂离子传输机制

Ionic conductivity is one of the most crucial properties of OICSEs, determining whether OICSEs apply to practical devices. Consequently, the design and development of OICSEs with high ionic conductivity is imperative. This objective necessitates an in-depth understanding of the lithium-ion transport mechanism, a fundamental aspect for advancing the efficacy of these electrolytes in technological applications. The structure of OICSEs is believed to contain three main components: inorganic fillers, polymers, and interfaces formed by the interaction of inorganic fillers with polymers. However, adequate technical knowledge is still lacking to probe these complex microscopic nanoscale interfaces directly. Currently, solid-state nuclear magnetic spectroscopy (NMR) is considered a practical technical approach for understanding the lithium-ion transport mechanisms in OICSEs.
离子导电性是 OICSE 最关键的特性之一，决定了 OICSE 是否适用于实际设备。因此，设计和开发具有高离子电导率的 OICSE 势在必行。要实现这一目标，就必须深入了解锂离子传输机制，这是提高这些电解质技术应用效率的一个基本方面。OICSE 的结构被认为包含三个主要部分：无机填料、聚合物以及无机填料与聚合物相互作用形成的界面。然而，目前仍缺乏足够的技术知识来直接探测这些复杂的微观纳米级界面。目前，固态核磁共振（NMR）被认为是了解 OICSE 中锂离子传输机制的实用技术方法。

Hu et al. first investigated the Li⁺ transport pathway in PEO (LiClO₄/LLZO) OICSEs using the ⁶Li-⁷Li isotope tracing technique [89]. By assembling the ⁶Li/OICSEs/⁶Li system, the ⁶Li replaced the ⁷Li during the electrochemical cycling. Therefore, quantitative analysis of the resonance before and after isotope labeling can accurately quantify the contribution of different Li-containing components to ion conduction. These results indicated that ⁶Li in the LLZO increased by 39% after cycling. In contrast, the ⁶Li in the PEO phase and the interface were negligible, suggesting that the Li-ions prefer to go through LLZO rather than the PEO or PEO/LLZO interface. Subsequently, they further systematically investigated the effect of LLZO content on the ion conduction mechanism (Fig. 3a) [90]. When the LLZO content was below equal to 20 wt%, Li ions were mainly conducted through the PEO matrix. However, when the LLZO content exceeds a critical point, i.e., the LLZO particle forms a permeation network, which blocks the Li-ion conduction channel in PEO, leading to a transition of Li transport from the PEO phase to the LLZO. The specific transition point depends on various factors, such as the inorganic fillers' size, morphology, and composition. Furthermore, incorporating plasticizers into OICSEs results in the ion transport pathway reorientation, favoring the polymer phase [91]. Our recent work further demonstrates that in OICSEs containing plasticizer (SN), Li ions are mainly transported through the polymer phase, with LLZTO and the interface acting as synergistic conductors (Fig. 3b) [88]. This is attributed to the plasticizer reducing the polymer crystallinity and increasing the amorphous region, which is more conducive to lithium-ion transport.
Hu 等人首先利用 ⁶Li-⁷Li 同位素示踪技术研究了 PEO（LiClO₄/LLZO ）OICSEs 中 Li⁶Li-⁷Li 的迁移途径[89]。通过组装 ⁶Li/OICSEs/⁶Li 系统，⁶Li 在电化学循环过程中取代了⁷Li 。因此，对同位素标记前后的共振进行定量分析，可以准确量化不同含锂成分对离子传导的贡献。这些结果表明，LLZO 中的 ⁶Li 在循环后增加了 39%。相比之下，PEO 相和界面中的 ⁶Li 可以忽略不计，这表明锂离子更愿意通过 LLZO 而不是 PEO 或 PEO/LLZO 界面。随后，他们进一步系统地研究了 LLZO 含量对离子传导机制的影响（图3a）[90]。当 LLZO 含量低于 20 wt% 时，锂离子主要通过 PEO 基体传导。然而，当 LLZO 含量超过临界点时，即 LLZO 颗粒形成渗透网络，阻塞了 PEO 中的锂离子传导通道，导致锂离子从 PEO 相过渡到 LLZO 相。具体的过渡点取决于各种因素，如无机填料的尺寸、形态和成分。此外，在 OICSE 中加入增塑剂会导致离子传输路径重新定向，有利于聚合物相[91]。 我们最近的工作进一步证明，在含有增塑剂（SN）的 OICSE 中，锂离子主要通过聚合物相进行传输，LLZTO 和界面起着协同导体的作用（图3b）[88]。这是因为增塑剂降低了聚合物的结晶度，增加了无定形区，从而更有利于锂离子传输。

Fig. 3 图 3

a ⁶Li NMR spectra of 5, 20, and 50 wt% LLZO-PEO/LiTFSI and 50 wt% LLZO-PEO/LiTFSI with TEGDME OICSEs before and after cycling and the corresponding Li-ion transport pathways [90], Copyright 2018, American Chemical Society. b ⁶Li NMR spectra of the LCPE-60 OICSEs before and after cycling and the Li-ion pathways [88], Copyright 2023 Elsevier. c ⁶Li NMR spectra of PAN (LiClO₄)-5 wt% LLZO NWs OICSEs before and after cycling [92], Copyright 2017, American Chemical Society. d ⁶Li MAS NMR of an LGPS-PEO (LiTFSI) OICSE before and after cycling [93], Copyright 2019, American Chemical Society. e Schematic illustration of the ion conduction pathway along the space charge regions [94], Copyright 2018 American Chemical Society. f Schematic diagram of the interface of H-OISE, OISE, and OISE-L Copyright 2024 Wiley‐VCH GmbH [96]
a⁶ 5、20 和 50 wt% LLZO-PEO/LiTFSI 以及 50 wt% LLZO-PEO/LiTFSI 与 TEGDME OICSE 在循环前后的锂 NMR 光谱以及相应的锂离子传输路径 [90], Copyright 2018, American Chemical Society.b⁶ LCPE-60 OICSEs 循环前后的锂 NMR 光谱及锂离子途径[88], Copyright 2023 Elsevier.c⁶ PAN (LiClO₄)-5 wt% LLZO NWs OICSEs 循环前后的锂 NMR 光谱[92], Copyright 2017, American Chemical Society.d⁶Li MAS NMR of an LGPS-PEO (LiTFSI) OICSEs before and after cycling [93], Copyright 2019, American Chemical Society.e 沿空间电荷区域的离子传导路径示意图 [94]，美国化学会版权所有，2018 年。f H-OISE、OISE 和 OISE-L 的界面示意图 [96], Copyright 2024 Wiley-VCH GmbH [96].

The interfacial region formed by the interaction of inorganic fillers and polymers plays an important role in OICSEs. However, the conduction mechanism of the interfacial region is very complex, and it largely depends on the specific composition and structure of OICSEs. Yang et al. investigated OICSEs containing 5.0 wt% LLZO nanowires combined with PAN using the⁶Li NMR technique (Fig. 3c) [92]. The results showed that the ⁶Li ions in the PAN at 0.9 ppm remained unchanged after cycling, while the amount of ⁶Li in the PAN region modified by LLZO (0.85 ppm) was greatly enhanced. This indicates that Li ions prefer to be transported through the PAN region modified by LLZO (usually understood as the interfacial region) rather than the unmodified PAN phase. Zheng et al. reported OICSEs with different LGPS and Li salt contents using the ball milling method (Fig. 3d) [93]. The results showed that the largest interface in PEO(LiTFSI)-(EO/Li = 9:1)-70 wt% LGPS, while the ionic conductivity of OICSEs was positively correlated with the LGPS-PEO interfaces quantified by ⁶Li NMR spectrum. Therefore, PEO (LiTFSI)- (EO/Li = 9:1)-70 wt% LGPS electrolytes have stronger Li ions transport and more stable long-term cycling performance with lithium metal. The ⁶Li NMR tracer exchange technique shows that Li ions are mainly transported through the LGPS/PEO interface. The result further demonstrates the interface plays a significant role in ion conduction. In addition to the interface detected by the ⁶Li NMR spectrum, Li et al. observed the 3 nm space charge region between Ga-LLZO and PEO with transmission electron microscopy (TEM) [94]. The Li ions in the Ga-LLZO lattice move towards the surface, resulting in vacancies that are positively charged on the surface and negatively charged inside. When the space charge region on the surface of the nanoparticles is connected (Fig. 3e), the results show that the space charge region at the interface is a fast conduction pathway for Li ions. Based on both computational and experimental results, similar behavior was also found in the LATP/PEO OICSE [95]. The LATP in PEO can establish low-energy barrier hopping channels along the surface for lithium-ion migration. In general, the mechanism of ion conduction within OICSEs is complex, and whether the lithium ions are transported through the polymer phase, the bulk phase, or the interface depends on several factors, such as the type and structural composition of the OICSE, including the inorganic fillers content, size, and morphology. In addition, the ability of the interface to be a phase with fast lithium ions conductivity depends on the interfacial interactions between the organic and inorganic materials. Guo et al.[54] investigated that under the coexistence of DMSO and LLZTO, the coupling of DMSO molecules with LLZTO resulted in the redistribution of the electron density of the DMSO molecules, which induced aggregation of the charges around the sulfinyl group, thereby increasing the Lewis basicity of the sulfinyl group and enhancing the interaction between LLZTO filler and PAN matrix. This enhancement facilitates the uniform encapsulation of the polymer on the particles surface and the formation of continuous Li⁺ conduction channels between the ceramic and polymer, which induces dehydrocyanation of the PAN matrix. The LLZTO@PAN electrolyte shows sufficient ionic conductivity of 1.1 × 10⁻⁴ S cm⁻¹, and a high Li⁺ transference number of 0.66. The Li|LLZTO@PAN/PEO|LFP cell delivers a high reversible capacity of 167 mAh g⁻¹ at 0.1 C, as well as a small polarization of 0.06 V. Therefore, it is beneficial to improve the ionic conductivity of OICSE by constructing a continuous micro interface of composite electrolyte. In recent research, the mechanism of microscopic interface formation in composite electrolytes and the ionic conductivity mechanism has been investigated using 1D ⁶Li and 2D ⁶Li-⁶Li exchange NMR techniques (Fig. 3f) [96]. The interface signals in the ⁶Li NMR spectra are from the lithium-deficient layer of LLZTO. At high current densities, Li ions are conducted through the polymer phase, and the lithium-deficient layer, as well as LLZTO, play a synergistic role in promoting ionic conduction, but the Li₂CO₃ on the surface of LLZTO inhibits the transport of the lithium-deficient layer as well as LLZTO.
无机填料和聚合物相互作用形成的界面区在 OICSE 中发挥着重要作用。然而，界面区的传导机制非常复杂，在很大程度上取决于 OICSE 的具体成分和结构。Yang 等人利用⁶Li NMR 技术研究了含有 5.0 wt% LLZO 纳米线和 PAN 的 OICSE（图3c）[92]。结果表明，PAN 中 0.9 ppm 的 ⁶Li 离子在循环后保持不变，而经 LLZO 修饰的 PAN 区域（0.85 ppm）中的 ⁶Li 离子量则大大增加。这表明锂离子更愿意通过被 LLZO 改性的 PAN 区域（通常理解为界面区域）而不是未改性的 PAN 相进行传输。Zheng 等人采用球磨法（图3d）[93]报道了不同 LGPS 和锂盐含量的 OICSE。结果表明，PEO(LiTFSI)-(EO/Li = 9:1)-70 wt% LGPS 中的界面最大，而通过 ⁶Li NMR 光谱量化的 OICSE 离子电导率与 LGPS-PEO 界面呈正相关。因此，PEO（LiTFSI）-（EO/Li = 9:1）-70 wt% LGPS 电解质具有更强的锂离子传输能力和更稳定的锂金属长期循环性能。⁶Li NMR示踪交换技术表明，锂离子主要通过 LGPS/PEO 界面传输。这一结果进一步证明了界面在离子传导中的重要作用。 除了 ⁶Li NMR 光谱检测到的界面外，Li 等人还用透射电子显微镜 (TEM) 观察到了 Ga-LLZO 和 PEO 之间 3 nm 的空间电荷区 [94] 。Ga-LLZO 晶格中的锂离子向表面移动，形成表面带正电、内部带负电的空位。当连接纳米粒子表面的空间电荷区时（图3e），结果表明界面上的空间电荷区是锂离子的快速传导通道。根据计算和实验结果，在 LATP/PEO OICSE 中也发现了类似的行为[95]。PEO 中的 LATP 可沿表面建立低能障跳跃通道，促进锂离子迁移。一般来说，OICSE 内的离子传导机制非常复杂，锂离子是通过聚合物相、体相还是界面传输取决于多个因素，例如 OICSE 的类型和结构组成，包括无机填料的含量、尺寸和形态。此外，界面能否成为具有快速锂离子传导性的相取决于有机材料和无机材料之间的界面相互作用。Guo 等[54]研究发现，在 DMSO 与 LLZTO 共存的情况下，DMSO 分子与 LLZTO 的耦合导致 DMSO 分子电子密度的重新分布，从而诱导了亚磺酰基周围电荷的聚集，从而增加了亚磺酰基的路易斯碱性，增强了 LLZTO 填料与 PAN 基体之间的相互作用。 这种增强促进了聚合物在颗粒表面的均匀封装，并在陶瓷和聚合物之间形成了连续的 Li⁺ 传导通道，从而诱导了 PAN 基体的脱氢氰化。LLZTO@PAN 电解质显示出足够的离子电导率（1.1 × 10^-4 S cm^-1 ）和较高的锂⁺ 转移数（0.66）。锂|LLZTO@PAN/PEO|LFP电池在 0.1 C 时的可逆容量高达 167 mAh g^-1 ，极化电压为 0.06 V。在最近的研究中，利用一维 ⁶Li 和二维 ⁶Li-⁶Li 交换核磁共振技术研究了复合电解质中微观界面的形成机理和离子导电机理（图 2）。3f）[96]。⁶Li NMR 光谱中的界面信号来自 LLZTO 的缺锂层。在高电流密度下，锂离子通过聚合物相传导，缺锂层和 LLZTO 在促进离子传导方面发挥了协同作用，但 LLZTO 表面的 Li₂CO₃ 会抑制缺锂层和 LLZTO 的传输。

To compare the pathways of Li-ion conduction more clearly in different OICSEs systems, Table 1 summarizes the ion conduction pathways based on polymer, filler type, content, and the presence or absence of plasticizer. It is shown that the ion conduction pathway of the OICSE is highly dependent on the filler content, polymer system, plasticizer, and circulating current density, but one certain thing is that the micro interface plays an important role in the ion conduction of the OICSE.
为了更清楚地比较锂离子在不同 OICSE 系统中的传导途径，表 1 总结了基于聚合物、填料类型、含量以及增塑剂存在与否的离子传导途径。结果表明，OICSE 的离子传导路径与填料含量、聚合物体系、增塑剂和循环电流密度有很大关系，但可以肯定的是，微界面在 OICSE 的离子传导中起着重要作用。

Table 1 Possible Li-ion conduction pathways in different OICSEs systems
表 1 不同 OICSE 系统中可能的锂离子传导途径

4 Key Inorganic Fillers and Advanced Structures in OICSEs
4 OICSE 中的关键无机填料和先进结构

OICSEs are composed of polymers, lithium salts, and inorganic fillers. In 1973, Wright et al. [97] proposed that mixing alkali metal salts with PEO can conduct Li ions. Currently, polymer matrices include PEO [98], copolyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) [99], polyvinylidene fluoride (PVDF) [100], polyethylene glycol diacrylate (PEGDA) [101], polymethyl methacrylate (PMMA) [102], polyvinyl carbonate (PVC) [103], tetramethyleneglycol methacrylate (TEGDMA) [104], and polystyrene (PS). These polymers are primarily semi-crystalline at RT, which limits chain segment movement, leading to low ionic conductivity (10⁻⁶ to 10⁻⁸ S cm⁻¹) [105]. When the temperature is above the glass transition temperature, these polymers are in the amorphous region, and the ionic conductivity increases significantly. Lithium salts are generally classified as inorganic lithium salts and organic lithium salts. Inorganic lithium salts such as lithium perchlorate (LiClO₄), lithium tetrafluoroborate (LiBF₄), lithium hexafluoroarsenate (LiAsF₆) [106], and lithium hexafluorophosphate (LiPF₆), while inorganic lithium salts are organic compounds consisting of an electron-absorbing group added to the anion. Common organic lithium salts include lithium borate dioxalate (LiBOB), lithium difluoroxalate borate (LiDFOB), lithium bis(difluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), which are highly solubility in polymers and quickly form stable SEI films. The inorganic fillers can be divided into inert fillers and active fillers depending on whether they can conduct Li ions. Inert fillers are not involved in the conductive process and include ZnO, TiO₂, SiO₂, ZrO₂, MgO, Al₂O₃, Y₂O₃, LiAlO₂, BaTiO₃, etc. [107, 108]; active fillers include garnet, chalcocite, NASICON, LISICON, perovskite, sulfide, Li₃N, etc. Both inert and active fillers are regarded as plasticizers to reduce crystallization and promote the movement of Li ions. The inorganic fillers are available in various shapes such as nanoparticles (0D), one-dimensional (1D) nanofibers, nanorods, two-dimensional (2D) nanosheets, and three-dimensional (3D) frameworks. The inorganic fillers with different shapes can provide long-range permeation networks through the arrangement to promote Li ions conduction and increase the diffusion rate, thus forming a fast Li ions conduction pathway.
OICSE 由聚合物、锂盐和无机填料组成。1973 年，Wright 等人[97]提出，将碱金属盐与 PEO 混合可传导锂离子。目前，聚合物基质包括 PEO [98]、共聚偏氟乙烯-六氟丙烯（PVDF-HFP）[99]、聚偏氟乙烯（PVDF）[100]、聚乙二醇二丙烯酸酯 (PEGDA) [101] 、聚甲基丙烯酸甲酯 (PMMA) [102] 、聚碳酸酯 (PVC) [103] 、甲基丙烯酸四亚甲基乙二醇酯 (TEGDMA) [104] 和聚苯乙烯 (PS)。这些聚合物在 RT 时主要呈半结晶状，这限制了链段的移动，导致离子导电率较低（10^-6 至 10^-8 S cm^-1 ）[105]。当温度高于玻璃转化温度时，这些聚合物处于无定形区，离子导电率会显著增加。锂盐一般分为无机锂盐和有机锂盐。无机锂盐如高氯酸锂（LiClO₄）、四氟硼酸锂（LiBF₄）、六氟砷酸锂（LiAsF₆）[106]、和六氟磷酸锂（LiPF₆），而无机锂盐则是在阴离子中加入吸电子基团的有机化合物。常见的有机锂盐包括二恶英硼酸锂（LiBOB）、二氟硼酸锂（LiDFOB）、双（二氟磺酰）亚胺锂（LiFSI）和双（三氟甲基磺酰基）亚胺锂（LiTFSI），它们在聚合物中的溶解度很高，能迅速形成稳定的 SEI 薄膜。 无机填料根据是否能传导锂离子可分为惰性填料和活性填料。惰性填料不参与导电过程，包括 ZnO、TiO₂、SiO₂、ZrO₂、MgO、Al₂O₃ 、Y₂O₃ 、LiAlO₂ 、BaTiO₃ 等。[107, 108]; 活性填料包括石榴石、方解石、NASICON、LISICON、透辉石、硫化物、Li₃N 等。惰性和活性填料都被视为增塑剂，可减少结晶并促进锂离子的移动。无机填料的形状多种多样，如纳米颗粒（0D）、一维（1D）纳米纤维、纳米棒、二维（2D）纳米片和三维（3D）框架。不同形状的无机填料可通过排列提供长程渗透网络，促进锂离子传导并提高扩散速率，从而形成快速的锂离子传导途径。

4.1 Polymer with Inert Fillers
4.1 含惰性填料的聚合物

4.1.1 0-Dimensional Inert Fillers
4.1.1 0 维惰性填料

0-dimensional (0D) inert materials are typically small filler particles with sizes ranging from a few nanometers to a few micrometers. These particles are introduced into polymer electrolytes with lithium salts to improve their mechanical properties, ionic conductivity, and electrochemical stability. This improvement is usually attributed to the inert fillers inhibiting the polymer crystallization, thus improving the chain segment motility. In addition, the Lewis acid–base interactions between groups on the nanoparticle surface and PEO chain segments, which can also facilitate the dissociation of lithium salts, have attracted extensive research. Croce et al. demonstrated that the improved electrochemical properties of PEO-based OICSEs were attributed to the –OH groups on the Al₂O₃ surface dispersed in the polymer matrix through the anionic “hydrogen bonding-mediated” solvation to reduce lithium salt association, thereby facilitating specific interactions between the filler, the polymer chain, and the ions from salt dissociation (Fig. 4a) [109]. Therefore, this objective can be achieved by incorporating more acidic sites, changing surface properties, or introducing functionalized nanomaterials. These strategies effectively inhibit polymer crystallization and enhance Lewis acid–base interactions between fillers, lithium salts, and polymer chains.
0 维（0D）惰性材料通常是尺寸从几纳米到几微米不等的小填料颗粒。将这些颗粒引入含锂盐的聚合物电解质中，可改善其机械性能、离子导电性和电化学稳定性。这种改善通常归因于惰性填料抑制了聚合物结晶，从而提高了链段的运动性。此外，纳米粒子表面的基团与 PEO 链段之间的路易斯酸碱相互作用也促进了锂盐的解离，这也吸引了大量研究。Croce 等人的研究表明，PEO 基 OICSE 的电化学性能之所以得到改善，是因为 Al₂O₃ 表面的 -OH 基团分散在聚合物基体中，通过阴离子 "氢键介导 "溶解作用减少了锂盐关联，从而促进了填料、聚合物链和盐解离离子之间的特定相互作用（图 3）。4a）[109]。因此，可以通过加入更多酸性位点、改变表面特性或引入功能化纳米材料来实现这一目标。这些策略可有效抑制聚合物结晶，增强填料、锂盐和聚合物链之间的路易斯酸碱相互作用。

Fig. 4 图 4

a Schematic diagram of the interaction between PEO chains and Al₂O₃ surface groups [109], Copyright 2004, Kluwer Academic Publishers. b Preparation process of SiO₂-UPy and schematic diagram of SHCPE with supermolecule network structure [110], Copyright 2019 Royal Society of Chemistry. c Morphology and synthesis diagram of the PEO-LiClO₄-SiO₂ OICSEs [111], Copyright 2020 American Chemical Society. d Preparation process diagram of p–V–SiO₂/PEO cross-linked OICSEs [113], Copyright 2021 Elsevier. e Synthetic routes of the PAN- insitu-SiO₂ OICSEs [114]. f Preparation process diagram of hollow PDA composite nanospheres and the TEM images of hollow SiO₂ and hollow PDA composites [115], Copyright 2022, American Chemical Society
a PEO 链与 Al₂O₃ 表面基团之间的相互作用示意图[109]，版权归 Kluwer Academic Publishers 2004 所有。b SiO₂-UPy 的制备过程和具有超分子网络结构的 SHCPE 示意图 [110]，版权所有，英国皇家化学会，2019 年。c PEO-LiClO₄-SiO₂ OICSE 的形态和合成示意图[111], Copyright 2020 American Chemical Society.d p-V-SiO₂/PEO 交联 OICSE 的制备过程图 [113], Copyright 2021 Elsevier.e PAN-原位-SiO₂ OICSE 的合成路线[114]。f 空心 PDA 复合纳米球的制备过程图以及空心 SiO₂ 和空心 PDA 复合材料的 TEM 图像 [115], Copyright 2022, American Chemical Society.

Xue et al. prepared an OICSE with a self-healing function by incorporating ureidopyrimidinone (UPy)-functionalized SiO₂ into a polymer matrix containing UPy units (SiO₂-UPy) [110], as shown in Fig. 4b. The OICSE shows a high ionic conductivity of 8.0 × 10⁻⁵ S cm⁻¹ at 30 °C compared with that of the CPE blended with pristine SiO₂. The improved ionic conductivity is attributed to the SiO₂-UPy filler being uniformly dispersed in the polymer matrix through PEG-UPy hydrogen bonding. This increases polymer activity and the number of physical cross-linking sites in the matrix, enhancing the interaction with PEG-UPy. Yang et al. constructed PEO@SiO₂ OICSEs with a 3D network structure of PEO and SiO₂ particles by in situ assembly (Fig. 4c). The fusion of monodisperse SiO₂ nanoparticles with 3D PEO successfully reduced the PEO crystallinity under the synergistic effect of strong Lewis acid–base and weak hydrogen bonding, achieving a high ionic conductivity of 1.1 × 10⁻⁴ S cm⁻¹, and wide electrochemical window of 4.8 V. vs Li/Li⁺[111]. In addition, the construction method significantly promoted the stability of the solid electrolyte interface. Similar research results were published in PAN-based systems [112]. An interconnected fast Li⁺ conducting network was constructed by in situ hydrolysis of tetraethoxysilane (TEOS) within a polyacrylonitrile (PAN) matrix. This situ-formed interconnected inorganic network provides a robust backbone for the OSE and a sufficiently continuous surface with Lewis acidic sites, which will facilitate the dissociation of Li salts. As a result, the OICSE obtained a promising ionic conductivity of 3.5 × 10⁻⁴ S cm⁻¹ and an attractive Young modulus of 8.627 GPa. When paired with a high-voltage cathode of LiNi_0.6Mn_0.2Co_0.2O₂, the ASSLBs exhibited a stable discharge capacity of 173.1 mAh g⁻¹ with 93.8% retention after 200 cycles at 3.0–4.3 V. Nanofillers with high specific surface area help increase the interaction between the inorganic filler and the polymer matrix, increase the free volume of the polymer. Park et al. introduced highly mesoporous silica nanoparticles (MSNs) into bulk polypropylene carbonate (PPC) matrices with bendability and high stability (Fig. 4d) [113]. OICSEs have an ultra-high lithium-ion transference number of 0.86 due to the strong Lewis acid sites on the surface of the highly mesoporous MSNs, which enhance the interaction with the polymer matrix, form a homogeneous Li-ion transport phase between the polymer matrix and ceramic fillers, and improve the Li⁺ transference number ion mobility number of the OICSEs.
Xue 等人将脲基嘧啶酮（UPy）功能化的 SiO₂ 加入含有 UPy 单元的聚合物基体（SiO₂-UPy ）[110]中，制备了一种具有自愈合功能的 OICSE，如图所示。4b。与混合了原始 SiO₂ 的 CPE 相比，OICSE 在 30 °C 时的离子导电率高达 8.0 × 10^-5 S cm^-1 。离子导电性的提高归功于 SiO₂-UPy 填料通过 PEG-UPy 氢键均匀地分散在聚合物基体中。这增加了聚合物的活性和基体中物理交联位点的数量，增强了与 PEG-UPy 的相互作用。Yang 等人通过原位组装构建了具有 PEO 和 SiO₂ 颗粒三维网络结构的 PEO@SiO₂ OICSE（图4c）。在强路易斯酸碱和弱氢键的协同作用下，单分散 SiO₂ 纳米粒子与三维 PEO 的融合成功地降低了 PEO 的结晶度，实现了 1.1×10^-4 S cm^-1 ，对 Li/Li⁺[111] 的电化学窗口为 4.8 V。此外，这种构造方法还大大提高了固体电解质界面的稳定性。在基于 PAN 的系统中也有类似的研究成果[112]。 通过原位水解聚丙烯腈（PAN）基质中的四乙氧基硅烷（TEOS），构建了一个相互连接的快速锂⁺ 导电网络。这种原位形成的相互连接的无机网络为 OSE 提供了坚固的骨架和具有路易斯酸位点的足够连续的表面，这将促进锂盐的解离。因此，OICSE 的离子电导率达到了 3.5 × 10^-4 S cm^-1 ，杨氏模量为 8.627 GPa。当与 LiNi_0.6Mn_0.2Co_0.2O₂ 的高压阴极配对时，ASSLBs 显示出 173.1 mAh g_{0.2O2 的稳定放电容量。高比表面积的纳米填料有助于增强无机填料与聚合物基体之间的相互作用，增加聚合物的自由体积。Park 等人将高介孔二氧化硅纳米颗粒（MSN）引入大块聚碳酸酯（PPC）基质中，使其具有可弯曲性和高稳定性（图 4d) [113]。OICSE 具有 0.86 的超高锂离子转移数，这是由于高介孔 MSN 表面的强路易斯酸位点增强了与聚合物基体的相互作用，在聚合物基体和陶瓷填料之间形成了均匀的锂离子传输相，并提高了 OICSE 的锂离子转移数⁺ 离子迁移率。}

In addition to the different Lewis acid–base interactions caused by the surface chemistry of the filler particles, there is another important way to improve the polarity and the dispersion of the filler in the polymer matrix by modifying the nanofiller surface. Zhan et al. reported OICSEs with porous vinyl-functionalized silicon (p–V–SiO₂) nanoparticles as fillers for PEO electrolytes with polyethylene glycol diacrylate (PEGDA) as a cross-linking agent (Fig. 4e) [114]. 10% p–V–SiO₂/PEO OICSE exhibited the highest ionic conductivity of 5.08 × 10⁻⁴ S cm⁻¹ at 60 °C, and a wide electrochemical stability window of 5.2 V vs. Li/Li⁺ based on Li|10% p–V–SiO₂/PEO OICSE|SS cell. The improved electrochemical performance is attributed to well-interfacial compatibility between organic and inorganic materials due to cross-linking polymerization reactions between porous SiO₂ and PEGDA in the PEO host, which promotes more lithium salt dissolution. Li et al. showed that the polydopamine (PDA) coated hollow silica nanoparticles were compatible with PEO and had a large interfacial contact area, as shown in Fig. 4f [115]. The thin polydopamine layer improved the compatibility with the polymer matrix and provided an effective and stable ion transport channel. Theoretical calculations show strong adsorption between polydopamine and TFSI⁻, which can inhibit the movement of TFSI⁻ anions. Compared with hollow SiO₂ without PDA coating, this assembled PEO@PDA-SiO₂ material exhibits higher ionic conductivity (1.89 × 10⁻⁴ S m⁻¹), a wide electrochemical window (5.33 V vs. Li/Li⁺), and good mechanical strength. In addition, OICSE delivers a reversible capacity of 134.9 mAh g⁻¹ after 205 cycles in comparison to 127.0 mAh g⁻¹ for the undoped electrolyte. The dispersion of inorganic fillers in polymers can also be improved by certain technical methods; for example, Xie et al. used atomic layer deposition (ALD) to uniformly distribute ZnO quantum dots within a PEO-based solid electrolyte matrix. This method achieved a strong chemical interaction between VPI–ZnO and PEO and a uniform distribution of VPI–ZnO in PEO [116]. The results show that the loose O–Li⁺ coordination on the top surface of the electrolyte and the remaining VPI–ZnO lead to a significant increase in the Li⁺ migration number and a decrease in the interfacial resistance to Li metal. Furthermore, the NCM811|Li half-cell with the VPI–ZnO/PEO/LiTFSI exhibits a high discharge capacity of 164.7 mAh g⁻¹ at 50 °C and has stable cycling performance.
除了由填料颗粒表面化学性质引起的不同路易斯酸碱相互作用外，还有一种重要方法可以通过改变纳米填料表面来提高填料在聚合物基质中的极性和分散性。Zhan 等人报道了以多孔乙烯基官能化硅（p-V-SiO₂）纳米粒子作为填充剂的 OICSE，用于以聚乙二醇二丙烯酸酯（PEGDA）为交联剂的 PEO 电解质（图4e）[114]。10% p-V-SiO₂/PEO OICSE 在 60 °C 时的离子电导率最高，达到 5.08 × 10^-4 S cm^-1 ，电化学稳定性窗口宽达 5.2 V vs. Li/Li⁺ 基于 Li|10% p-V-SiO₂/PEO OICSE|SS 电池。电化学性能的提高归因于多孔 SiO₂ 与 PEO 主基中的 PEGDA 发生交联聚合反应，使有机材料与无机材料之间具有良好的界面相容性，从而促进了更多的锂盐溶解。Li 等人的研究表明，如图4f[115]所示，聚多巴胺（PDA）包覆的空心二氧化硅纳米粒子与 PEO 相容性好，界面接触面积大。聚多巴胺薄层提高了与聚合物基体的相容性，并提供了有效而稳定的离子传输通道。理论计算表明，聚多巴胺与 TFSI^- 之间有很强的吸附作用，可以抑制 TFSI^- 阴离子的移动。 与没有 PDA 涂层的空心 SiO₂ 相比，这种组装的 PEO@PDA-SiO₂ 材料具有更高的离子电导率（1.89 × 10^-4 S m^-1 ）、宽电化学窗口（5.33 V vs. Li/Li⁺ ）和良好的机械强度。此外，与未掺杂电解质的 127.0 mAh g^-1 相比，OICSE 在 205 个循环后可提供 134.9 mAh g^-1 的可逆容量。无机填料在聚合物中的分散也可以通过某些技术方法得到改善；例如，Xie 等人使用原子层沉积（ALD）技术将氧化锌量子点均匀地分布在基于 PEO 的固体电解质基质中。这种方法实现了 VPI-ZnO 与 PEO 之间强烈的化学作用，以及 VPI-ZnO 在 PEO 中的均匀分布[116]。结果表明，电解质顶面松散的 O-Li⁺ 配位和剩余的 VPI-ZnO 导致 Li⁺ 迁移数显著增加，并降低了锂金属的界面电阻。此外，采用 VPI-ZnO/PEO/LiTFSI 的 NCM811|Li 半电池在 50 °C 下具有 164.7 mAh g^-1 的高放电容量和稳定的循环性能。

Besides 0-dimensional inert oxides, ferroelectric materials can be incorporated into the polymer matrix as 0-dimensional inert materials, such as PbTiO₃, BaTiO₃, and SrBi₄Ti₄O₁₅ [117, 118]. The ferroelectric materials exhibit strong Lewis acid–base characteristics, which can increase the polarity of polymer chains and further enhance the ionic conductivity in the interface region. Table 2 shows typical examples of 0D inert metal oxides and ferroelectric-filled materials in OICSEs.
除了 0 维惰性氧化物，铁电材料也可以作为 0 维惰性材料加入聚合物基体中，例如 PbTiO₃、BaTiO₃ 和 SrBi₄Ti₄O₁₅ [117, 118] 。铁电材料具有很强的路易斯酸碱特性，这可以增加聚合物链的极性，进一步提高界面区的离子导电性。表 2 显示了 OICSE 中 0D 惰性金属氧化物和铁电填充材料的典型示例。

Table 2 Properties of OICSEs with 0-dimensional inert fillers
表 2 含有 0 维惰性填料的 OICSE 的特性

4.1.2 1-Dimensional Inert Fillers
4.1.2 一维惰性填料

One factor that improves the ionic conductivity of inert nanoparticles in OICSEs is the inhibition of the crystallization of polymers and an increase in the amorphous ratio. Another key factor is the suitable filler content that can provide a continuous percolation conduction pathway, thus significantly improving ionic conductivity. When the 0D inert filler concentration reaches a certain level in the polymer matrix, it leads to the accumulation of the particle filler, which severely affects lithium-ion conduction. Therefore, the 1D nanotube and nanofiber instead of 0D inert fillers are a reasonable choice to provide continuous percolation paths and improve the conductive behavior.
提高 OICSE 中惰性纳米粒子离子导电性的一个因素是抑制聚合物结晶和增加无定形比率。另一个关键因素是合适的填料含量，它可以提供连续的渗滤传导途径，从而显著提高离子传导性。当聚合物基体中的 0D 惰性填料浓度达到一定水平时，会导致颗粒填料的堆积，从而严重影响锂离子传导。因此，采用一维纳米管和纳米纤维代替 0D 惰性填料是提供连续渗流路径和改善导电性能的合理选择。

Conventional 1D inert materials are mainly metal oxide nanowires, such as Y₂O₃ [135], TiO₂ [136, 137], CeO₂ [138], and Al₂O₃ [30]. Cui et al. reported a CSE containing Y₂O₃-doped ZrO₂ (YSZ) nanowires with positively charged oxygen vacancies [135]. The results showed that the doped 7 mol% YSZ nanowires achieved the highest ionic conductivity of 1.07 × 10⁻⁵ S cm⁻¹ at 30 °C, which is much higher than that of the electrolyte (2.98 × 10⁻⁶ S cm⁻¹) containing 7% YSZ nanoparticles. The improved conductivity of the OICSE originates from the oxygen vacancies on the nanowire surface, which can act as Lewis acid sites to bind to the anions, as shown in Fig. 5a, effectively improving the ionic conductivity of the PAN-based OICSEs. Tao et al. reported PEO-based OICSEs containing 10% Mg₂B₂O₅ nanowires, as shown in Fig. 5b [139]. The results showed that the ionic conductivity achieved 1.53 × 10⁻⁴ S cm⁻¹ at 40 °C. This is attributed to the interaction of Mg²⁺ ions on the surface of Mg₂B₂O₅ nanowires as Lewis acid centers with the anion TFSI⁻, thus weakening the interaction between Li⁺ and TFSI⁻, which in turn promoted the dissolution of the lithium salt and released more Li ions. In addition, the Mg₂B₂O₅ nanowires have abundant Lewis acid sites [137], which enable the migration of Li ions in the two-phase interface between the electrolyte and Mg₂B₂O₅ nanowires. TiO₂ nanorod-filled polypropylene carbonate (PPC)-based OICSEs were prepared for the first time by Jing et al. The results indicate that the OICSE films with TiO₂ nanorods can significantly improve the ionic conductivity (1.52 × 10⁻⁴ S cm⁻¹) and have a stability electrochemical window (> 4.6 V vs. Li⁺/Li based on Li|OICSE|SS cell) and a tensile strength of 27 MPa at RT. This is attributed to the TiO₂ nanorods providing more continuous lithium-ion transport channels and their surface porosity and composition improving the interfacial contact between polymer and filler and Lewis acid–base reaction sites.
传统的一维惰性材料主要是金属氧化物纳米线，如 Y₂O₃ [135], TiO₂ [136、137] 、CeO₂ [138] 和 Al₂O₃ [30] 。Cui 等人报道了一种含有带正电氧空位的 Y₂O₃ 掺杂 ZrO₂ (YSZ) 纳米线的 CSE [135] 。结果表明，掺杂 7 mol% 的 YSZ 纳米线在 30 °C 时的离子电导率最高，达到 1.07 × 10^-5 S cm^-1 ，远高于电解质的离子电导率（2.98 × 10^-6 S cm^-1 ）。如图5a所示，OICSE导电性的提高源于纳米线表面的氧空位，它可以作为路易斯酸位点与阴离子结合，从而有效提高了基于 PAN 的 OICSE 的离子导电性。Tao 等人报道了含有 10% Mg₂B₂O₅ 纳米线的 PEO 基 OICSE，如图 5b [139] 所示。结果表明，在 40 °C 时，离子导电率达到了 1.53 × 10^-4 S cm^-1 。 这归因于 Mg²⁺ 离子在 Mg₂B₂O₅ 纳米线表面作为路易斯酸中心与阴离子 TFSI^- 的相互作用、从而削弱了 Li⁺ 与 TFSI^- 之间的相互作用，进而促进了锂盐的溶解，释放出更多的锂离子。此外，Mg₂B₂O₅ 纳米线具有丰富的路易斯酸位点[137]、这使得锂离子能够在电解质和 Mg₂B₂O₅ 纳米线之间的两相界面中迁移。Jing 等人首次制备了填充 TiO₂ 纳米棒的聚碳酸丙酯（PPC）基 OICSE，结果表明含有 TiO₂ 纳米棒的 OICSE 薄膜能显著提高离子电导率（1.52 × 10^-4 S cm^-1 ），并具有稳定的电化学窗口（基于 Li|OICSE|SS 电池，对 Li⁺/Li > 4.6 V）和在 RT 下 27 MPa 的拉伸强度。这归功于 TiO₂ 纳米棒提供了更连续的锂离子传输通道，其表面多孔性和成分改善了聚合物和填料之间的界面接触以及路易斯酸碱反应位点。

Fig. 5 图 5

a Schematic illustration for Li-ion transport with nanoparticle and nanowire fillers [135], Copyright 2016, American Chemical Society. b Schematics of lithium-ion migration in Mg₂B₂O₅ enhanced OICSEs [139], Copyright 2018, American Chemical Society. c Schematic diagram of TDI modified TiO₂ and OICSE preparation [140], Copyright 2021 Elsevier. d Schematic diagram for the OICSEs fabrication procedure [141], Copyright 2022 Royal Society of Chemistry. e Schematic illustration depicting the formation of OICSEs incorporating silica nanotubes with hollow nanostructures [142] Copyright, 2020 Elsevier. f A mechanism to improve ionic conductivity by adding HNTs [143], Copyright 2018 Royal Society of Chemistry. g Schematic diagram of PEO-based HNTs electrolyte [144], Copyright 2019, American Chemical Society
a 使用纳米粒子和纳米线填料的锂离子迁移示意图 [135]，美国化学学会版权所有，2016 年。b Mg₂B₂O₅ 增强型 OICSE 中的锂离子迁移示意图 [139]，版权归美国化学会所有，2018 年。c TDI 改性 TiO₂ 和 OICSE 制备示意图[140], Copyright 2021 Elsevier.d OICSE 制作过程示意图 [141]，版权归英国皇家化学会所有，2022 年。e OICSEs 的形成示意图，其中包含具有中空纳米结构的二氧化硅纳米管 [142] ，版权归 2020 年爱思唯尔所有。f 添加 HNTs 提高离子导电性的机制 [143], Copyright 2018 Royal Society of Chemistry.g 基于 PEO 的 HNTs 电解质示意图 [144]，美国化学学会版权所有，2019 年。

Beyond integrating one-dimensional (1D) nanomaterials into the polymer matrix, the ionic conductivity can be further augmented through surface chemical modification. Li et al. successfully prepared a novel organic–inorganic cross-linked PEO-TDI-TiO₂ electrolyte film using toluene-2,4-diisocyanate (TDI) as a modifier, as shown in Fig. 5c [140]. The OICSE membrane has a high ionic conductivity of 1 × 10⁻⁴ S cm⁻¹ at 30 °C, and a high Li⁺ transference number of 0.36 at 60 °C. The wide electrochemical window (5.5 V vs. Li⁺/Li) was determined by LSV with the asymmetric battery of Li foil|OICSE| stainless steel (SS). The surface modification of TDI helps reduce the surface energy of TiO₂ nanowires, thus enabling the polymer matrix chains to form effective covalent bonds with the nanofillers. Furthermore, the cross-linked and branched network structure effectively increases the amorphous regions in the polymer matrix. Zhao et al. reported a filler surface coating method, which involves coating a polydopamine (PDA) layer on the TiO₂ nanofibers surface and then incorporating it into the PEO matrix (Fig. 5d) [141]. This coating method inhibited the filler aggregation in the PEO matrix and enhanced the compatibility between the PEO matrix and the PDA. The strong lithophilic layer of PDA also improved the ionic conductivity behavior at the filler/polymer interface, enabling the OICSEs to exhibit a high ionic conductivity of 4.36 × 10⁻⁴ S cm⁻¹ and a wide electrochemical window of 5 V versus Li⁺/Li at 55 °C were studied by LSV using a Li|OICSE|SS cell. Xue et al. successfully synthesized a series of one-dimensional silica nanotubes (SNts) with hollow nanostructures and high uniformity by etching rod-shaped nickel hydrazine complexes for PEO-SNts (Fig. 5e) [142]. Compared with OICSEs based on 0D silica nanoparticles, PEO-SNts indicate significantly improved conductivity, thermal stability, and cycling stability.
除了将一维（1D）纳米材料整合到聚合物基体中，还可以通过表面化学改性进一步增强离子导电性。如图5c[140]所示，Li 等人使用甲苯-2,4-二异氰酸酯（TDI）作为改性剂，成功制备了新型有机-无机交联 PEO-TDI-TiO₂电解质膜。OICSE 膜在 30 °C 时具有 1 × 10^-4 S cm^-1 的高离子电导率，在 60 °C 时具有 0.36 的高 Li⁺ 透射率。锂箔|OICSE|不锈钢（SS）的不对称电池通过 LSV 确定了宽电化学窗口（5.5 V vs. Li⁺/Li ）。TDI 的表面改性有助于降低 TiO₂ 纳米线的表面能，从而使聚合物基体链与纳米填料形成有效的共价键。此外，交联和支化网络结构有效地增加了聚合物基体中的无定形区域。Zhao 等人报道了一种填料表面涂覆方法，即在 TiO₂ 纳米纤维表面涂覆一层聚多巴胺 (PDA)，然后将其加入 PEO 基体中（图 5d ）[141]。这种涂层方法抑制了填料在 PEO 基质中的聚集，增强了 PEO 基质与 PDA 之间的相容性。PDA 的强亲石层还改善了填料/聚合物界面的离子传导性，使 OICSEs 的离子传导性高达 4。薛等人利用LSV技术，使用Li|OICSE|SS电池研究了55 °C下36 × 10^-4 S cm^-1 和5 V对Li⁺/Li 的宽电化学窗口。Xue 等人通过蚀刻 PEO-SNts 的棒状镍肼络合物，成功合成了一系列具有中空纳米结构和高均匀性的一维二氧化硅纳米管（SNts）（图5e）[142]。与基于 0D 硅纳米颗粒的 OICSE 相比，PEO-SNts 在导电性、热稳定性和循环稳定性方面都有显著提高。

Halloysite nanotubes (HNTs) are a unique natural 1D nanomaterial in addition to metal oxide 1D materials. It has the characteristics of tubular nanostructures, high aspect ratio, versatility, good biocompatibility, and high mechanical strength, and has received widespread attention in many fields. HNTs are a hydrated polycrystalline 1:1 layered silicate clay mineral with an outer siloxane surface and an inner alumina core. Therefore, the outer surface is generally negatively charged, like SiO₂. Chen et al. prepared an OICSE-5 by introducing 5% natural halloysite nanotubes (HNTs) into polyvinylidene fluoride (PVDF). The ionic conductivity (3.5 × 10⁻⁴ S cm⁻¹) was improved by ten orders of magnitude at 30 °C compared to the electrolyte without HNTs (Fig. 5f) [143]. The improvement in ionic conductivity was mainly attributed to the negatively charged outer surface and high specific surface area of HNTs, which facilitated the migration of Li ions in PVDF. However, the interfacial compatibility of HNT nanotubes with LFP electrodes is poor. To address this issue, Miller et al. reported a modification method in which a small amount of LFP was added during the preparation of OICSEs (Fig. 5g) [144]. This modification increased ionic conductivity, and the compatibility between electrolyte and electrode was significantly enhanced. Moreover, the electrochemical stability window was improved to 5.14 V, and the Li⁺ transference number was 0.46. The HNTLFP/SPE-based LFP polymer batteries present stable discharge capacities of 120 ± 3 mAh g⁻¹ at 0.5 C after 300 discharge/charge cycles. In addition, metal–organic framework (MOF) nanorods and nickel phosphate (VSB) nanorods can also be introduced into the polymer matrix as effective 1D solid fillers to improve the electrochemical performance of OICSEs [145,146,147,148].
霍洛石纳米管（HNTs）是金属氧化物一维材料之外的一种独特的天然一维纳米材料。它具有管状纳米结构、高纵横比、多功能性、良好的生物相容性和高机械强度等特点，在许多领域受到广泛关注。HNT 是一种水合多晶 1:1 层状硅酸盐粘土矿物，其外表面为硅氧烷，内核为氧化铝。因此，外表面通常带负电荷，如 SiO₂。Chen 等人通过在聚偏氟乙烯（PVDF）中引入 5% 的天然海泡石纳米管（HNT）制备了 OICSE-5。与不含 HNT 的电解质相比，30 °C 时的离子电导率（3.5 × 10^-4 S cm^-1）提高了十个数量级（图 5f ）[143]。离子电导率的提高主要归功于 HNT 带负电的外表面和高比表面积，这有利于锂离子在 PVDF 中的迁移。然而，HNT 纳米管与 LFP 电极的界面相容性较差。为了解决这个问题，Miller 等人报道了一种改性方法，即在制备 OICSE 时加入少量 LFP（图5g）[144]。这种改性提高了离子传导性，电解质与电极之间的相容性也显著增强。此外，电化学稳定性窗口提高到 5.14 V，锂⁺ 转移数为 0.46。基于 HNTLFP/SPE 的 LFP 聚合物电池在 0.0 V 和 0.5 V 电压下的稳定放电容量为 120 ± 3 mAh g^-1 。5 C。此外，金属有机框架（MOF）纳米棒和磷酸镍（VSB）纳米棒也可作为有效的一维固体填料引入聚合物基体，以改善 OICSE 的电化学性能[145、146,147,148] 。

4.1.3 2-Dimensional and 3-Dimensional Inert Fillers
4.1.3 二维和三维惰性填料

Previous studies have demonstrated that inert nanoparticles and nanofibers can enhance ionic conductivity by suppressing the polymer crystallinity and providing continuous ionic conduction channels. To further enhance the ionic conductivity and improve the mechanical properties of OICSEs, researchers introduced 2D nanosheets and even developed 3D inorganic framework nanostructures. These structures provide continuous three-dimensional channels with no cross-connections between the inorganic phases. The thermal stability and mechanical properties were significantly improved by modulating the contact-specific surface area of the polymer with the filler. In recent works, 2D inert materials in OICSEs mainly include graphene oxide (GO), montmorillonite (MMT), boron nitride (BN), and MXenes nanomaterials. In contrast, 3D inorganic framework materials mainly cover metal oxides (e.g., Al₂O₃, SiO₂, BaTiO₃) and glass fibers. The typical examples of the electrochemical performance of OICSEs containing 2D nanosheet structures and 3D network frameworks are summarized in Table 3.
以往的研究表明，惰性纳米粒子和纳米纤维可以通过抑制聚合物结晶性和提供连续的离子传导通道来增强离子传导性。为了进一步提高离子传导性并改善 OICSE 的机械性能，研究人员引入了二维纳米片，甚至开发了三维无机框架纳米结构。这些结构提供了连续的三维通道，无机相之间没有交叉连接。通过调节聚合物与填料的接触比表面积，热稳定性和机械性能得到了显著改善。在最近的研究中，OICSE 中的二维惰性材料主要包括氧化石墨烯（GO）、蒙脱石（MMT）、氮化硼（BN）和 MXenes 纳米材料。相比之下，三维无机框架材料主要包括金属氧化物（例如 Al₂O₃, SiO₂, BaTiO₃ ）和玻璃纤维。表3总结了含有二维纳米片结构和三维网络框架的 OICSE 的典型电化学性能示例。

Table 3 Properties of OICSEs with 2-dimensional and 3-dimensional inert fillers
表 3 含有二维和三维惰性填料的 OICSE 的特性

GO is a graphene derivative with a two-dimensional layered structure that contains various hydrophilic functional groups such as –C–O–C, –CO, –COOH, and –OH on the surface, giving it excellent hydrophilicity and dispersibility. Xu et al. added 1 wt% of graphene oxide (GO) to PEO-based electrolytes for OICSEs and achieved an ionic conductivity of 1.54 × 10⁻⁵ S cm⁻¹ at 24 °C [149], Li⁺ transference number of 0.42. The wide electrochemical window (about 5 V vs. Li⁺/Li) was measured by LSV using Li|GO-modified PEO|SS. The symmetric Li||GO-PEO||Li cell was stably cycled at an overpotential of 27 mV for 600 h, as shown in Fig. 6a. In addition, the LiFePO₄//GO-PEO//Li cell exhibited excellent cycling, with a discharge capacity of 142 mAh g⁻¹ at 0.5 C and 91% capacity retention after 100 cycles, indicating that it can inhibit the growth of lithium dendrites. The enhancement of ionic conductivity depends on the continuity of the conduction channels and the lithium-ion concentration. Thus, the ionic conductivity of OICSEs can be further enhanced by increasing the local lithium-ion concentration in the interfacial regions. Wu et al. synthesized lithiated polydopamine-modified graphene oxide nanosheets (LiDGO) and doped them into a PEO matrix, as shown in Fig. 6b [150]. A comprehensive evaluation of the electrochemical properties showed that the long-range conduction pathway with localized lithium-ion concentration constructed at the PEO/LiDGO interface significantly enhanced the ionic conductivity of OICSEs. The ionic conductivity reached 3.4 × 10⁻⁵ S cm⁻¹ at 30 °C and had excellent mechanical stability. The full battery achieves a discharge capacity of ~ 156 mAh g⁻¹ after 200 cycles with ultra-high-capacity retention of 98.7%. Xiong et al. introduced interatomic lithium montmorillonite (Li-MMT) into lithium-sulfur batteries for the first time and achieved free migration and exchange of interlayer cations in a thick sulfur cathode [151]. This work demonstrated that natural montmorillonite clay possesses a cation exchange function and can facilitate conduction by replacing other cations with Li ions. Zhang et al. prepared an OICSE consisting of poly(ethylene carbonate), layered lithium montmorillonite (LiMNT), and high-pressure fluorocarbon subethylenes (PEC) using a combination of solution casting and hot pressing [152]. The OICSE acquires a high ionic conductivity of 3.5 × 10⁻⁴ S cm⁻¹ and a high Li⁺ transference number of 0.83 at 25 °C. A wide electrochemical window of 4.6 V versus Li⁺/Li was evaluated by LSV using Li foil|OICSE|SS. The mechanism of the enhanced Li⁺ transference number in OICSE is attributed to the selective immobilization of charged species. The upper and lower surfaces of the nanoflake LiMNT equipping –Si–O–Si- silicon tetrahedral sheets are negatively charged, and edge-shared faces consisting of –Al–OH groups are positively charged (Fig. 6c). When the PEC-Li polymer electrolyte is inserted into the intercalation of LiMNT, this surface difference allows selective immobilization of the charged material. The lithium salt anions are more likely to approach the edges of LiMNT, while the Li⁺ cations are more likely to be present in the intercalation space. Meanwhile, the carbonate group (–O–(C=O)–O–) with many lone pair electrons in the PEC will interact with the free Li⁺. This interaction leads to an ordered entry of Li⁺ into the interlayer space. As a result, this arrangement shortens the Li⁺ transport pathway and provides an efficient transport channel resulting in a high Li⁺ transfer number. To effectively solve the inhomogeneous ion transport problem and improve the thermal stability and mechanical properties of OICSEs. Ding et al. utilized a directional freezing method to prepare vertically aligned MMT arrays with ultra-low curvature (Fig. 6d) [153]. A uniform and continuous ion-conductive interface was formed in the OICSEs through UV-induced polymerization, facilitating Li⁺ migration. The results demonstrated that CSE/VAMMT exhibited higher Li-ion transference numbers and ionic conductivity at RT (1.08 mS cm⁻¹). Moreover, it displayed excellent cycling stability, with no short-circuiting during continuous lithium deposition/stripping for 1000 h. The 2D BN nanosheets have attracted considerable attention due to the ability of the B atoms to interact with the anions of lithium salts as Lewis acid sites on the planar surface, thereby releasing more Li ions and enhancing ionic conductivity [154]. Zheng et al. developed a hybrid polymer electrolyte (BN-PEO-PVDF) containing 2D BN nanosheets, as shown in Fig. 6e [155]. In addition to improving ionic conductivity and mechanical properties, BN enhanced the thermal stability of the PEO-based electrolyte, allowing the BN-PEO-PVDF electrolyte to balance thermal changes faster and achieve more uniform ion transport. Ding et al. introduced g-C₃N₄ nanosheets similar to BN into PEO-based electrolytes, improving electrochemical performance, mechanical properties, and thermal stability [156]. Furthermore, MXene is a common 2-dimensional metal carbide layered material with a negative charge due to the surface with rich polar groups, such as –OH, –Cl, and –F. It has a strong interaction with lithium salts, which helps in the dissociation of lithium salts. Yang et al. incorporated insulating MXene-mSiO₂ nanosheets into the PEO electrolyte, as shown in Fig. 6f [157]. Due to the abundant functional groups of MXene-mSiO₂, the Lewis acid–base interactions between the PEO chain and anions were promoted, enabling the rapid transport of Li⁺ ions across the mesoporous nanosheet/polymer interface. As a result, the OICSE exhibited high ionic conductivity of 4.6 × 10⁻⁴ S cm⁻¹ and Young's modulus of 10.5 MPa, Young's modulus is 34 orders of magnitude higher than that of the silica particle/ePPO electrolyte. Noteworthy, the full cell exhibits a long and stable cycle performance up to 250 cycles under 0.5 C at 25 °C, and the capacity is well maintained at 141.8 mAh g⁻¹, much higher than that of the LFP cathodes with pure ePPO electrolyte (60.3 mAh g⁻¹).
GO 是一种具有二维层状结构的石墨烯衍生物，表面含有多种亲水官能团，如 -C-O-C、-CO、-COOH 和 -OH，因此具有极佳的亲水性和分散性。Xu 等人在用于 OICSEs 的 PEO 基电解质中添加了 1 wt% 的氧化石墨烯 (GO)，离子电导率达到了 1.54 × 10^-5 S cm^-1 ，温度为 24 °C [149], Li⁺ 传递数为 0.42。通过 LSV 测量了使用 Li|GO 改性 PEO|SS 的宽电化学窗口（对 Li⁺/Li 约 5 V）。如图6a所示，对称的 Li||GO-PEO||Li 电池在 27 mV 的过电位下稳定循环了 600 小时。此外，LiFePO₄/GO-PEO//Li 电池的循环性能极佳，在 0.5 C 下的放电容量为 142 mAh g^-1 ，循环 100 次后容量保持率为 91%，这表明它可以抑制锂枝晶的生长。离子传导性的增强取决于传导通道的连续性和锂离子浓度。因此，可以通过提高界面区的局部锂离子浓度来进一步增强 OICSE 的离子导电性。如图 6b [150] 所示，Wu 等人合成了锂化多巴胺修饰的氧化石墨烯纳米片（LiDGO），并将其掺杂到 PEO 基体中。对电化学特性的综合评估表明，在 PEO/LiDGO 界面构建的局部锂离子浓度长程传导通路显著提高了 OICSE 的离子传导性。 在 30 °C 时，离子电导率达到 3.4 × 10^-5 S cm^-1 ，并具有出色的机械稳定性。经过 200 次循环后，完整电池的放电容量达到约 156 mAh g^-1 ，超高容量保持率为 98.7%。Xiong 等人首次在锂硫电池中引入了原子间蒙脱石锂（Li-MMT），并在厚硫正极中实现了层间阳离子的自由迁移和交换[151]。这项工作证明了天然蒙脱石粘土具有阳离子交换功能，可以通过用 Li 离子取代其他阳离子来促进传导。Zhang 等人采用溶液浇铸和热压相结合的方法制备了一种由聚（碳酸乙烯酯）、层状蒙脱石锂（LiMNT）和高压碳氟亚乙基（PEC）组成的 OICSE [152]。在 25 °C 时，OICSE 获得了 3.5 × 10^-4 S cm^-1 的高离子电导率和 0.83 的高 Li⁺ 转移数。使用锂箔|OICSE|SS，通过 LSV 评估了 4.6 V 对 Li⁺/Li 的宽电化学窗口。OICSE 中 Li⁺ 传递数增强的机制归因于带电物种的选择性固定。含有-Si-O-Si-硅四面体片的纳米片状 LiMNT 的上下表面带负电，而由-Al-OH 基团组成的边缘共享面带正电（图6c）。 当 PEC-Li 聚合物电解质插入到 LiMNT 的夹层中时，这种表面差异可以选择性地固定带电材料。锂盐阴离子更有可能接近锂纳米碳管的边缘，而锂⁺ 阳离子则更有可能存在于插层空间。同时，PEC 中具有许多孤对电子的碳酸盐基团（-O-(C=O)-O-）将与游离的 Li⁺ 发生相互作用。这种相互作用导致 Li⁺ 有序进入层间空间。因此，这种排列缩短了锂⁺ 的传输路径，提供了一个高效的传输通道，从而产生了较高的锂⁺ 传输数。为了有效解决不均匀离子传输问题，提高 OICSE 的热稳定性和机械性能。Ding 等人利用定向冷冻法制备了超低曲率垂直排列的 MMT 阵列（图 6d) [153]。通过紫外线诱导聚合，在 OICSE 中形成了均匀连续的离子导电界面，从而促进了 Li⁺ 的迁移。结果表明，CSE/VAMMT 在 RT 时具有更高的锂离子转移数和离子电导率（1.08 mS cm^-1）。此外，它还表现出卓越的循环稳定性，在连续 1000 小时的锂沉积/剥离过程中未出现短路现象。 二维 BN 纳米片之所以备受关注，是因为其平面上的 B 原子能够作为路易斯酸位点与锂盐的阴离子相互作用，从而释放出更多的锂离子并增强离子导电性[154]。Zheng 等人开发了一种含有二维 BN 纳米片的混合聚合物电解质（BN-PEO-PVDF），如图6e所示[155]。除了改善离子传导性和机械性能外，BN 还增强了 PEO 基电解质的热稳定性，使 BN-PEO-PVDF 电解质能够更快地平衡热变化，实现更均匀的离子传输。Ding 等人在 PEO 基电解质中引入了与 BN 相似的 g-C₃N₄ 纳米片，提高了电化学性能、机械性能和热稳定性[156]。此外，MXene 是一种常见的二维金属碳化物层状材料，由于表面含有丰富的极性基团（如 -OH、-Cl 和 -F）而带有负电荷。它与锂盐有很强的相互作用，有助于锂盐的解离。Yang 等人在 PEO 电解液中加入了绝缘的 MXene-mSiO₂ 纳米片，如图 6f [157] 所示。由于 MXene-mSiO₂ 含有丰富的官能团，促进了 PEO 链与阴离子之间的路易斯酸碱相互作用，使 Li⁺ 离子能够在介孔纳米片/聚合物界面上快速传输。因此，OICSE 的离子电导率高达 4.6 × 10^-4 S cm^-1 和杨氏模量为 10.5 MPa，杨氏模量比二氧化硅颗粒/ePPO 电解质高出 34 个数量级。值得注意的是，在 25 °C、0.5 C 条件下，全电池表现出长而稳定的循环性能，循环次数可达 250 次，容量保持在 141.8 mAh g^-1 ，远高于采用纯 ePPO 电解质的 LFP 阴极（60.3 mAh g^-1）。

Fig. 6 图 6

a Voltage–time profiles of Li||GO-PEO||Li at 60 °C and cyclic performance of full battery at 1C [149], Copyright 2021, American Chemical Society. b Schematic diagram of the preparation of LiDGO nanosheets [150], Copyright 2020 Elsevier. c Schematic diagram of ion migration mechanism of LiMNT interlayer insertion into PEC-based electrolyte [152], Copyright 2019 WILEY. d Schematic diagram of the manufacturing process of GPE/VAMMT [153], Copyright 2022 Xinyang Li. e Schematic diagram of heat transfer in electrolytes with and without BN additives [155], Copyright 2020 Guangyuan Wesley Zheng. f Schematic diagram of the manufacturing containing MXene mSiO₂ [157], Copyright 2020 WILEY
a Li||GO-PEO||Li在60 °C时的电压-时间曲线和完整电池在1C时的循环性能[149]，美国化学会版权所有，2021年。b LiDGO 纳米片的制备示意图 [150]，爱思唯尔版权所有，2020 年。c LiMNT 层间插入基于 PEC 的电解质的离子迁移机制示意图[152], Copyright 2019 WILEY.d GPE/VAMMT 制造工艺示意图 [153], Copyright 2022 Xinyang Li.e 含有和不含 BN 添加剂的电解质中的传热示意图 [155], Copyright 2020 Guangyuan Wesley Zheng.f 含 MXene mSiO₂ 的制造示意图 [157], Copyright 2020 WILEY.

In recent years, the ice template method, electrostatic spinning, sol–gel method, and 3D inorganic skeletons have been reported to construct continuous ion transport channels to form 3D OICSEs. The strategy of building OICSE with a three-dimensional skeleton structure solves the accumulation problem and further improves mechanical strength. Zhang et al. reported an OICSE with vertically aligned and continuous nanoscale ceramic-polymer interfaces using modified Al₂O₃ as the skeleton and PEO as the polymer matrix, as shown in Fig. 7a [158]. The Li⁺ transport along the ceramic/polymer interface was demonstrated for the first time, and the interfacial ionic conductivity was predicted to be higher than 10⁻³ S cm⁻¹ at 0 °C, as shown in Fig. 7b. The ionic conductivity was 5.82 × 10⁻⁴ S cm⁻¹ at RT, which was four orders of magnitude higher than that of the OICSE with nanoparticles and nanowires. The improvement of ionic conductivity is mainly attributed to the high aspect ratio of the polymer/ceramic interface formed by the vertically aligned 3D Al₂O₃ and the polymer matrix, which allows Li ions to conduct along the continuous vertically aligned interface and effectively reduces the crystallization of the polymer. Han et al. explored a simple and efficient solution-blowing technique to prepare well-aligned BaTiO₃ nanofibers with an average diameter of about 300 nm combined with PEO polymers to form OICSEs [159]. Compared with the electrolyte without BaTiO₃, the ionic conductivity increased from 5.74 × 10⁻⁶ to 5.83 × 10⁻⁵ S cm⁻¹ at 30 °C, and the Li/Li⁺ electrochemical stability window was increased to about 5.8 V. To further enhance the ionic conductivity and electrochemical stability of OICSEs, Zhang et al. introduced an ionic liquid into a PEO-based 3D glass fiber cloth (PEO@GFC-25%ILs) framework (Fig. 7c) [160]. The results showed that PEO@GFC-25%ILs exhibited a high ionic conductivity of 1.6 × 10⁻⁴ S cm¹ at RT, and an electrochemical window of 5.2 V versus Li⁺/Li was performed by assembling a Li|OICSE|SS cell. The Li|PEO@GFC-25%ILs|Li cells also demonstrated excellent cycling performance and rate capability with stable cycling of 2000 h. The full batteries assembled based on LCO and LFP cathode with PEO@GFC-25% ILs electrolyte can achieve specific capacities of 128.3 mAh g⁻¹ and 155.2 mAh g⁻¹, respectively. Furthermore, the LFP/PEO@GFC-25% ILs/Li battery can provide a reversible capacity of 152.0 mAh g⁻¹ after 150 cycles at 0.5 C. To improve the mechanical properties of OICSEs to effectively suppress the occurrence of lithium dendrites and achieve high ionic conductivity at RT. Cui et al. synthesized a novel 3D SiO₂ aerogel backbone by sol–gel method, injected with PEGDA, SN, and LiTFSI, and finally formed OICSEs by ultraviolet photocuring (Fig. 7d) [161]. This interconnected SiO₂ aerogel strengthens the skeletal structure of all the OICSEs and offers a substantial and uninterrupted surface area for anion adsorption, creating a highly conductive pathway. As a result, the OICSEs achieve a high modulus of approximately 0.43 GPa and a remarkable ionic conductivity of 6 × 10⁻⁴ S cm ⁻¹ at 30 °C.
近年来，冰模板法、静电纺丝法、溶胶-凝胶法和三维无机骨架法等构建连续离子传输通道以形成三维 OICSE 的研究已见诸报端。以三维骨架结构构建 OICSE 的策略解决了积聚问题，并进一步提高了机械强度。Zhang 等人报道了一种以改性 Al₂O₃ 为骨架、PEO 为聚合物基质、具有垂直排列和连续纳米级陶瓷-聚合物界面的 OICSE，如图 7a [158] 所示。如图7b所示，首次证实了 Li⁺ 沿陶瓷/聚合物界面的传输，并预测 0 °C 时界面离子电导率高于 10^-3 S cm^-1 。在 RT 时，离子电导率为 5.82 × 10^-4 S cm^-1 ，比含有纳米颗粒和纳米线的 OICSE 高四个数量级。离子电导率的提高主要归功于垂直排列的三维 Al₂O₃ 与聚合物基体形成的聚合物/陶瓷界面的高纵横比，这使得锂离子能够沿着连续的垂直排列界面传导，并有效减少了聚合物的结晶。Han 等人探索了一种简单高效的溶液吹制技术，制备出平均直径约为 300 nm、排列整齐的 BaTiO₃ 纳米纤维，并将其与 PEO 聚合物结合形成 OICSE [159]。 与不含 BaTiO₃ 的电解质相比，离子电导率从 5.74 × 10^-6 增加到 5.83 × 10^-5 S cm^-1 ，锂/锂⁺ 电化学稳定性窗口提高到约 5.为了进一步提高 OICSE 的离子导电性和电化学稳定性，Zhang 等人在基于 PEO 的三维玻璃纤维布 (PEO@GFC-25%ILs) 框架中引入了离子液体（图 7c) [160] 。结果表明，PEO@GFC-25%ILS 在 RT 条件下表现出 1.6 × 10^-4 S cm¹ 的高离子电导率，通过组装 Li|OICSE|SS 电池，与 Li⁺/Li 的电化学窗口为 5.2 V。基于 LCO 和 LFP 正极与 PEO@GFC-25% ILs 电解质组装的完整电池的比容量分别为 128.3 mAh g^-1 和 155.2 mAh g^-1 。此外，LFP/PEO@GFC-25% ILs/Li 电池在 0.5 C 下循环 150 次后，可提供 152.0 mAh g^-1 的可逆容量。Cui 等人采用溶胶-凝胶法合成了新型三维 SiO₂ 气凝胶骨架，并注入 PEGDA、SN 和 LiTFSI，最后通过紫外光固化形成了 OICSE（图 2）。7d) [161]。这种相互连接的 SiO₂ 气凝胶加强了所有 OICSE 的骨架结构，并为阴离子吸附提供了大量不间断的表面积，形成了一个高度导电的通道。因此，OICSE 在 30 °C 时具有约 0.43 GPa 的高模量和 6 × 10^-4 S cm ^-1 的显著离子电导率。

Fig. 7 图 7

a Schematics of OICSEs with three types of geometrical structures. b Ionic conductivity in different regions of composite electrolytes [158], Copyright 2018, American Chemical Society. c Schematic illustration for preparation of PEO@GFC-25%ILs [160], Copyright 2020 Elsevier. d Schematic diagram of the microstructure of OICSEs containing 3D SiO₂ aerogel [161], Copyright 2018 WILEY
a 具有三种几何结构的 OICSE 示意图。b 复合电解质不同区域的离子电导率[158]，美国化学学会版权所有，2018 年。c PEO@GFC-25%ILs 的制备示意图[160], Copyright 2020 Elsevier.d 含有 3D SiO₂ 气凝胶的 OICSE 的微观结构示意图[161], Copyright 2018 WILEY

Although the significant enhancement effect of aligned structures on ion conduction behavior has been demonstrated, the methods for preparing these structures still need to be more thoroughly explored. Some limitations and challenges may still exist in the current preparation methods, such as process complexity, material selection, and interface engineering. Further research can be devoted to the development of simpler, scalable preparation methods while optimizing material combinations and interfacial interactions for more efficient ion conduction and optimized electrochemical properties. In addition, the long-term stability, cycle life, and compatibility with electrodes of these aligned structures also need to be explored to ensure reliability and durability in practical applications. In summary, although the aligned structures have potential in ion conduction behavior, further research extensions are still needed to realize their practical applications.
虽然对齐结构对离子传导行为的明显增强作用已得到证实，但制备这些结构的方法仍有待更深入的探索。目前的制备方法可能还存在一些限制和挑战，如工艺复杂性、材料选择和界面工程。进一步的研究可以致力于开发更简单、可扩展的制备方法，同时优化材料组合和界面相互作用，以提高离子传导效率和优化电化学性能。此外，还需要探索这些排列结构的长期稳定性、循环寿命以及与电极的兼容性，以确保实际应用中的可靠性和耐用性。总之，尽管排列结构在离子传导行为方面具有潜力，但要实现其实际应用，仍需要进一步的研究扩展。

Table 4 shows the advantages and disadvantages of inert materials with different dimensions, where the 0D inert materials have good mechanical properties and chemical stability, but low ionic conductivity and poor interfacial contact. 1D Nanowires/nanotubes are beneficial to some extent to improve interfacial contact and inhibit crystallization of polymers, especially when the orientation is consistent, and can provide continuous interfacial conduction for Li-ions, but the preparation process is complicated. The 2D inert materials with high specific surface area, good interfacial contact, and rich functional groups on the surface (e.g., MXene-Ti₃C₂ and BN, which contain functional groups such as –OH, –O, –NH₂, and –F.) can interact with Li ions in the OICSEs and further promote Li-ion migration, but have poor mechanical properties. The 3D inert material has high mechanical strength, and thermal stability, which promotes the formation of a continuous conductive interface with the polymer and improves the ionic conductivity of the OICSEs, but the preparation method is complicated and requires special equipment.
表4显示了不同尺寸惰性材料的优缺点，其中 0D 惰性材料具有良好的机械性能和化学稳定性，但离子导电率低，界面接触性差。一维纳米线/纳米管在一定程度上有利于改善界面接触和抑制聚合物结晶，尤其是在取向一致的情况下，并能为锂离子提供连续的界面传导，但制备工艺复杂。二维惰性材料具有高比表面积、良好的界面接触性和表面丰富的官能团（例如MXene-Ti₃C₂ 和 BN，它们含有 -OH、-O、-NH₂ 和 -F 等官能团）可以与 OICSE 中的锂离子相互作用，进一步促进锂离子迁移，但机械性能较差。三维惰性材料具有较高的机械强度和热稳定性，可促进与聚合物形成连续的导电界面，提高 OICSE 的离子导电性，但制备方法复杂，需要特殊的设备。

Table 4 Advantages and disadvantages of inert materials in different dimensions
表 4 不同尺寸惰性材料的优缺点

4.2 Polymer with Active Fillers
4.2 含有活性填料的聚合物

Active fillers have high ionic conductivity and electrochemical activity relative to inert fillers, and they can participate in electrochemical reactions and provide additional ion transport channels, thereby improving the ionic conductivity and the electrochemical performance. Therefore, active materials are known as fast ion conductors and could provide a highly efficient pathway for Li-ion. However, the active fillers may lead to a certain degree of electrode polarization and capacity degradation, and their properties need to be optimized and regulated to improve the cycle life and stability of the battery. Typical active materials based on solid-state electrolytes consist of sulfide-type, garnet-type, NASICON-type, and perovskite-type materials.
相对于惰性填料，活性填料具有较高的离子传导性和电化学活性，并且可以参与电化学反应，提供额外的离子传输通道，从而提高离子传导性和电化学性能。因此，活性材料被称为快速离子导体，可为锂离子提供一个高效通道。然而，活性填料可能会导致一定程度的电极极化和容量衰减，因此需要对其特性进行优化和调节，以提高电池的循环寿命和稳定性。基于固态电解质的典型活性材料包括硫化物型、石榴石型、NASICON 型和透辉石型材料。

4.2.1 Polymer Matrix Incorporating Sulfide-Type Materials
4.2.1含有硫化物类材料的聚合物基质

Sulfide electrolytes are characterized by substituting sulfur ions for oxygen ions, resulting in larger ion transport pathways for Li ions. As a result, they exhibit relatively high ionic conductivity, typically ranging from 10⁻³ to 10⁻² S cm⁻¹, comparable to liquid electrolytes. However, sulfide electrolytes have poor electrochemical stability and unstable interface contact with lithium metal, leading to decomposition reactions and high interfacial impedance [186]. Generally, sulfide electrolytes are combined with polymers or lithium alloys as anodes to improve interface stability.
硫化物电解质的特点是用硫离子代替氧离子，从而为锂离子提供更大的离子传输通道。因此，硫化物电解质的离子电导率相对较高，通常在 10^-3 到 10^-2 S cm^-1 之间，与液态电解质相当。然而，硫化物电解质的电化学稳定性较差，与锂金属的界面接触不稳定，导致分解反应和高界面阻抗 [186]。通常，硫化物电解质与聚合物或锂合金结合作为阳极，以提高界面稳定性。

Xu et al. developed an OICSE by incorporating Li₁₀GeP₂S₁₂ (LGPS) as an active filler into a PEO matrix. The OICSE with 1 wt% LGPS exhibited higher ionic conductivity than that of the PEO-LiTFSI electrolyte, with values of 1.18 × 10⁻⁵ S cm⁻¹ at 25 °C and 1.21 × 10⁻³ S cm⁻¹ at 80 °C, and had a wide electrochemical window of 5.7 V versus Li⁺/Li [187]. This result is attributed to the inhibition of PEO crystallization by LGPS, which weakens the interaction between Li⁺ and PEO chains. Furthermore, adding LGPS particles to the PEO matrix enhanced the Li⁺ transference number and electrochemical stability. The LFP||Li batteries using the PEO-LiTFSI-1 wt% LGPS OICSE demonstrated a high capacity of 148.6 mAh g⁻¹ at 0.5 C and 60 °C, with a capacity retention of 92.5% after 50 cycles. To further improve the uniform dispersion of nanofillers within a polymer matrix, Xu et al. introduced a novel in-situ synthesis method for Li₃PS₄ to create a PEO/Li₃PS₄ OICSE, as shown in Fig. 8a [188]. The results show that the in-situ synthesized Li₃PS₄ nanoparticles exhibit superior dispersion within the PEO matrix than mechanical mixing, which is conducive to forming Li⁺ conductive channels and enhancing ion transport. Specifically, the OICSE containing 2 vol% Li₃PS₄ by in-situ synthesized method demonstrated the highest ionic conductivity of 8.01 × 10⁻⁴ S cm⁻¹ at 60 °C, surpassing the ionic conductivity of mechanically mixed electrolytes at 6.98 × 10⁻⁴ S cm⁻¹. Additionally, the assembled solid-state LiFePO₄/Li battery with the OICSE displayed outstanding cycling performance with a capacity retention of 80.9% after 325 cycles at 60 °C and remarkable rate capability (127 mAh g⁻¹ at 1 C). In efforts to enhance the chemical stability of sulfides in an air environment, as well as to improve electrode material compatibility, Wang et al. have successfully designed a novel sulfide-doped OICSE. This OICSE combines inorganic sulfide, specifically lithium-sulfur saltpeter (Li₇PS₆), with a polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) [189]. Incorporating Li₇PS₆ within a PVDF-HFP polymer matrix imparts flexibility and air stability to the OICSE while ensuring commendable chemical and electrochemical stability. Notably, the PVDF-HFP-Li₇PS₆ electrolyte exhibited excellent ionic conductivity of 1.1 × 10⁻⁴ S cm⁻¹ at RT (Fig. 8b), and the Li||Li symmetric cell achieved stable cycling of up to 1000 h at 0.2 mA cm⁻². In addition, the LiFePO₄||CSE||Li cell displays an impressive specific capacity of 160 mAh g⁻¹ over 150 cycles, indicating that sulfide-doped OICSEs are promising for high-performance solid-state lithium batteries. Zhang et al. engineered a thin sulfide electrolyte film (65 μm) through the modified Li_6PS₅Cl and PEO, as shown in Fig. 8c [190]. The assembled Li-In ||LiNi_0.7Co_0.2Mn_0.1O₂ ASSLBs with the OICSE exhibit 74% capacity retention and an average coulombic efficiency of 99.85% after 1000 cycles at 60 °C with high loading conditions (4.46 mAh cm⁻²). Liu et al. prepared ultrathin flexible OICSE from Li₆PS₅Cl and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) through the electrostatic spinning infiltration-hot-pressing method, shown in Fig. 8d [191]. The strong polarity of the polymer facilitates the interaction with LSPSCl. The P(VDF-TrFE) network allows full penetration of the LPSCl particles and the formation of an interpenetrating P(VDF-TrFE) structure. The ionic conductivity reached 1.2 × 10⁻³ S cm⁻¹, enabling the Li-In||LiNi_0.8Co_0.1Mn_0.1O₂ cell to maintain 71% capacity after 20,000 cycles at 1.0 mA cm⁻² (Fig. 8e). To inhibit the growth of polysulfide shuttles and lithium dendrites, Su et al. designed an ASSLB with a flexible composite cathode and PEO-LSPSCl-LiTFSI (S-CPE) [192]. The cell still maintained 97.8% capacity retention after 100 cycles of 0.1 A g⁻¹. Low-temperature transmission electron microscopy (Cryo-TEM) revealed the presence of abundant Li₂CO₃ particles at the Li/PEO interface (Fig. 8f), which hindered the Li⁺ transport. However, at the Li/S-CPE interface, LSPSCl promoted the decomposition of TFSI⁻ to form abundant Li₂O nanocrystals, amorphous LiF, and Li₂S layers, which suppressed the Li dendrites growth of and stabilized the interface (Fig. 8g). Furthermore, the comprehensive elemental mapping through EDS unveiled the distinct presence of elemental constituents such as O, F, S, and C within the structure of S-CPE (Fig. 8h). It is notably imperative to highlight that the pronounced O signal strength in the analysis suggests an intricate process involving Li deposition coupled with the formation of Li₂O. This work provides a strategy to mitigate the polysulfide shuttle effect and lithium dendrite formation for the design of solid-state lithium-based batteries with high energy density. Table 5 summarizes typical examples of the electrochemical performance of OICSE with sulfide-type fillers.
Xu 等人在 PEO 基体中加入 Li₁₀GeP₂S₁₂ (LGPS) 作为活性填料，开发出一种 OICSE。与 PEO-LiTFSI 电解质相比，含有 1 wt% LGPS 的 OICSE 表现出更高的离子电导率，25 °C 时为 1.18 × 10^-5 S cm^-1 ，25 °C 时为 1.21 × 10^-3 S cm^-1 在 80 °C 时，对 Li⁺/Li [187]具有 5.7 V 的宽电化学窗口。这一结果归因于 LGPS 对 PEO 结晶的抑制作用，它减弱了 Li⁺ 与 PEO 链之间的相互作用。此外，在 PEO 基体中添加 LGPS 颗粒还能提高锂⁺ 的转移数量和电化学稳定性。使用 PEO-LiTFSI-1 wt% LGPS OICSE 的 LFP||Li 电池在 0.5 C 和 60 °C 条件下显示出 148.6 mAh g^-1 的高容量，循环 50 次后容量保持率达 92.5%。为了进一步提高纳米填料在聚合物基体中的均匀分散性，Xu 等人引入了一种新的原位合成方法。提出了一种新颖的原位合成 Li₃PS₄ 的方法，以创建 PEO/Li₃PS₄ OICSE，如图所示。8a[188]。结果表明，原位合成的 Li₃PS₄ 纳米粒子在 PEO 基质中的分散性优于机械混合，这有利于形成 Li⁺ 导电通道并增强离子传输。 具体来说，采用原位合成法制备的含有 2 vol% Li₃PS₄ 的 OICSE 在 60 °C 时的离子电导率最高，达到 8.01 × 10^-4 S cm^-1 ，超过了机械混合电解质 6.98 × 10^-4 S cm^-1 的离子电导率。此外，使用 OICSE 组装的固态 LiFePO₄/Li 电池显示出出色的循环性能，在 60 °C 下循环 325 次后，容量保持率为 80.9%，并且具有显著的速率能力（1 C 下为 127 mAh g^-1 ）。为了提高硫化物在空气环境中的化学稳定性并改善电极材料的兼容性，Wang 等人成功设计出了一种新型硫化物掺杂 OICSE。这种 OICSE 结合了无机硫化物，特别是锂硫硝石（Li₇PS₆）和聚偏氟乙烯-六氟丙烯共聚物（PVDF-HFP）[189]。在 PVDF-HFP 聚合物基质中加入 Li₇PS₆ 可增强 OICSE 的柔韧性和空气稳定性，同时确保出色的化学和电化学稳定性。值得注意的是，PVDF-HFP-Li₇PS₆ 电解质在 RT 条件下表现出 1.1 × 10^-4 S cm^-1 的优异离子电导率（图 2）。8b），锂||锂对称电池在 0.2 mA cm^-2条件下实现了长达 1000 小时的稳定循环。 此外，LiFePO₄|||CSE|||Li 电池在 150 次循环中显示出 160 mAh g^-1 的惊人比容量，表明掺硫化物的 OICSE 有望用于高性能固态锂电池。Zhang 等人通过改性 Li_6PS₅Cl 和 PEO 制备了一层硫化物电解质薄膜（65 μm），如图 8c [190] 所示。组装的锂-铟||锂镍_0.7Co_0.2Mn_0.1O₂ 具有 OICSE 的 ASSLB 在 60 °C 高负载条件下循环 1000 次后，容量保持率为 74%，平均库仑效率为 99.85%（4.46 mAh cm^-2）。Liu 等人通过静电纺丝浸润-热压法，利用 Li₆PS₅Cl 和聚（偏氟乙烯-三氟乙烯）（P(VDF-TrFE)）制备了超薄柔性 OICSE，如图所示。8d[191]。聚合物的强极性促进了与 LSPSCl 的相互作用。P(VDF-TrFE)网络允许 LPSCl 颗粒充分渗透，并形成相互渗透的 P(VDF-TrFE) 结构。离子电导率达到 1.2 × 10^-3 S cm^-1 ，使 Li-In||LiNi_0.8Co_0.1Mn_0.1O₂ 电池在 1.0 mA cm^-2 下循环 20,000 次后仍能保持 71% 的容量（图8e）。 为了抑制多硫梭子和锂枝晶的生长，Su 等人设计了一种具有柔性复合正极和 PEO-LSPSCl-LiTFSI (S-CPE) 的 ASSLB [192]。该电池在 0.1 A g^-1 的 100 个循环后仍能保持 97.8% 的容量。低温透射电子显微镜（Cryo-TEM）显示，在 Li/PEO 界面存在大量的 Li₂CO₃ 颗粒（图8f），阻碍了 Li⁺ 的传输。然而，在 Li/S-CPE 界面，LSPSCl 促进了 TFSI^- 的分解，形成了丰富的 Li₂O 纳米晶、无定形 LiF 和 Li₂S 层，从而抑制了锂枝晶的生长并稳定了界面（图 2）。8g）。此外，通过 EDS 进行的全面元素绘图揭示了 S-CPE 结构中明显存在的元素成分，如 O、F、S 和 C（图8h）。特别需要强调的是，分析中明显的 O 信号强度表明了一个复杂的过程，其中涉及锂的沉积和 Li₂O 的形成。这项工作为设计具有高能量密度的固态锂电池提供了减轻多硫化物穿梭效应和锂枝晶形成的策略。表5总结了带有硫化物型填料的 OICSE 电化学性能的典型实例。

Fig. 8 图 8

a Process flow diagram of in-situ preparation of PEO-Li₃PS₄ OICSE [188], Copyright 2018 Elsevier. b Schematic illustration of OICSE and Arrhenius plots of Li₇PS₆, OICSE, and PVDF-HFP/LiTFSI polymer electrolyte. [189], Copyright 2020, American Chemical Society. c Cycling performance of modified Li₆PS₅Cl-PEO and Li in alloy cathodes [190], Copyright 2020 Elsevier. d Schematic illustration of LPSCl@P(VDF-TrFE) OICSEs via an electrospinning-infiltration hot-pressing method. e Long-term cycling performance of LPSCl@P(VDF-TrFE) OICSEs at 1.0 mA cm⁻² [191], Copyright 2022 Wiley. f Cryo-TEM characterization of the Li/PEO interfaces. g Cryo-TEM characterization of the Li/S-CPE interfaces. h EDS elemental maps of S-CPE [192], Copyright 2022 Wiley
a 原位制备 PEO-Li₃PS₄ OICSE 的工艺流程图[188], Copyright 2018 Elsevier.b OICSE 和 Li₇PS₆ 、OICSE 和 PVDF-HFP/LiTFSI 聚合物电解质的阿伦尼乌斯图示意图。[189]，美国化学学会版权所有，2020 年。c 改性 Li₆PS₅Cl-PEO 和 Li 合金阴极的循环性能 [190]，爱思唯尔版权所有，2020 年。d 通过电纺-过滤热压法制备 LPSCl@P(VDF-TrFE) OICSE 的示意图。e LPSCl@P(VDF-TrFE) OICSEs 在 1.0 mA cm^-2 [191] 下的长期循环性能，版权归 2022 Wiley 所有。f Li/PEO 界面的 Cryo-TEM 表征。g 锂/S-CPE 接口的 Cryo-TEM 表征。h S-CPE 的 EDS 元素图 [192], Copyright 2022 Wiley

Table 5 Electrochemical properties of OICSEs with sulfide-type materials
表 5 含有硫化物型材料的 OICSE 的电化学特性

4.2.2 Polymer Matrix Incorporating Garnet-Type Materials
4.2.2含有石榴石型材料的聚合物基质

The garnet-type solid-state electrolyte materials are typically lithium-ion conductors like Li₇La₃Zr₂O₁₂ (LLZO) and their derivatives. They are known as fast ion conductors, exhibiting relatively high ionic conductivity from 10⁻⁴ to 10⁻³ S cm⁻¹ [204]. When using LLZO particles, it is important to ensure that the surface is fresh, as Li₂CO₃ and LiOH are easily formed when exposed to the air. In addition, these materials possess a wide electrochemical window, outstanding chemical stability, excellent mechanical strength, and the ability to suppress lithium dendrite growth effectively. Incorporating garnet-type fillers within polymer electrolytes has demonstrated promise in mitigating the issues associated with lithium dendrite growth while enhancing the overall electrochemical performance.
石榴石型固态电解质材料通常是锂离子导体，如 Li₇La₃Zr₂O₁₂ (LLZO) 及其衍生物。它们是众所周知的快速离子导体，表现出相对较高的离子电导率，从 10^-4 到 10^-3 S cm^-1 [204]。在使用 LLZO 颗粒时，必须确保其表面是新鲜的，因为 Li₂CO₃ 和 LiOH 在暴露于空气中时很容易形成。此外，这些材料还具有宽广的电化学窗口、出色的化学稳定性、优异的机械强度以及有效抑制锂枝晶生长的能力。在聚合物电解质中掺入石榴石型填料有望缓解与锂枝晶生长相关的问题，同时提高整体电化学性能。

Lee et al. [205] evaluated the ionic conductivity of OICSEs, consisting of different tetragonal LLZO contents with PEO matrix. The results showed that the OICSE containing 52.5 wt% LLZO indicated the highest ionic conductivity of 4.42 × 10⁻⁴ S cm⁻¹ at 55 °C and was higher than that of the OICSE containing 52.5 wt% Al₂O₃ inert material (10⁻⁶ S cm⁻¹). This phenomenon arises from the synergistic effect resulting from the combination of the polymer and the active LLZO filler, consequently enhancing the ionic conductivity. Goodenough et al. compared the ionic conductivity of OICSEs prepared from SiO₂ and LLTO nanoparticles as inert and active fillers, respectively [69]. The OICSE with LLTO nanoparticle showed an ionic conductivity of 1.9 × 10⁻⁵ S cm⁻¹, which is twice times higher than OICSE with SiO₂ nanoparticle. This improvement of LLTO nanoparticles is due to the fast interphase conduction between the active filler and the PEO matrix. Most importantly, the OICSE with LLTO framework showed the highest ionic conductivity of 8.8 × 10⁻⁵ S cm⁻¹ at 25 °C, which was higher than that of both active (LLTO particles) and inert (SiO₂ particles) fillers. This is due to the 3D framework with PEO can provide continuous ion transport channels compared to nanoparticles, avoiding the accumulation of particles, and thus effectively improving the ion transport properties. He et al. achieved high ionic conductivity of 2.39 × 10⁻⁴ S cm⁻¹ at 25 °C by incorporating LLZO nanowires into a PEO electrolyte (PLLN), and a wide electrochemical window of 6 V versus Li⁺/Li was measured by LSV using Li|OICSE|SS, as shown in Fig. 9a [206]. The tensile strength of PLLN increases to nearly 1.0 MPa with a maximum strain of 2092% owing to the high rigidness and good dispersity of LLZO nanowires. The all-solid-state LFP/PLLN/Li batteries exhibit a favorable specific capacity of 158.8 mAh g⁻¹ after 70 cycles at 0.5 C under 60 °C and a specific capacity of 158.7 mAh g⁻¹ after 80 cycles at 0.1 C under 45 °C. The uniform dispersion of LLZO nanowires in the polymer led to a significant enhancement in both the ionic conductivity and mechanical strength of the OICSE. The Li||Li symmetric battery assembled by the OICSE exhibits stable cycling performance for 1000 h at 60 °C without a short circuit. Li et al. synthesized 3D garnet-type LLZO monomers by employing skimmed cotton as a template for fabricating flexible solid-state LLZO/PEO LiTFSI electrolytes (Fig. 9b) [207]. This OICSE achieves ionic conductivity of 0.89 × 10⁻⁴ S cm⁻¹ and exhibits a wide electrochemical window of 5.5 V versus Li⁺/Li using Li|OICSE|SS. ASSLBs matched with LiFePO₄ exhibited high cycle stability and rate performance. To reduce the tortuosity of the ion conduction path, Hu et al. employed wood as a template, in conjunction with the polymer PEO, to fabricate a garnet framework structure with a highly conductive multiscale arrangement from a top-down approach (Fig. 9c) [208]. The structure exhibits an impressive ionic conductivity of 1.8 × 10⁻⁴ S cm⁻¹ and excellent mechanical flexibility at RT. Notably, the ionic conductivity closely approximates the bulk conductivity, and the impact of the garnet/polymer interface is significantly amplified. The low-curvature garnet wood structure, serving as a highly conductive solid-state electrolyte, demonstrates substantial potential and offers a valuable model for research aimed at the design and optimization of OICSEs.
Lee 等人[205]评估了由不同四方 LLZO 含量和 PEO 矩阵组成的 OICSE 的离子电导率。结果表明，含有 52.5 wt% LLZO 的 OICSE 在 55 °C 时的离子电导率最高，为 4.42 × 10^-4 S cm^-1 ，高于含有 52.5 wt% Al₂O₃ 惰性材料的 OICSE（10^-6 S cm^-1 ）。这种现象源于聚合物和活性 LLZO 填料结合产生的协同效应，从而增强了离子导电性。Goodenough 等人比较了分别以 SiO₂ 和 LLTO 纳米粒子作为惰性和活性填料制备的 OICSE 的离子导电性[69]。含有 LLTO 纳米粒子的 OICSE 的离子电导率为 1.9 × 10^-5 S cm^-1 ，是含有 SiO₂ 纳米粒子的 OICSE 的两倍。LLTO 纳米粒子的这种改进是由于活性填料和 PEO 基体之间的快速相间传导。最重要的是，带有 LLTO 框架的 OICSE 在 25 °C 时显示出最高的离子传导性，达到 8.8 × 10^-5 S cm^-1 ，高于活性填料（LLTO 颗粒）和惰性填料（SiO₂ 颗粒）。这是因为与纳米颗粒相比，含有 PEO 的三维框架可以提供连续的离子传输通道，避免颗粒堆积，从而有效改善离子传输性能。He 等人 如图所示，通过将 LLZO 纳米线与 PEO 电解质（PLLN）结合，在 25 °C 时实现了 2.39 × 10^-4 S cm^-1 的高离子电导率，并通过 LSV 使用 Li|OICSE|SS 测得相对于 Li⁺/Li 的 6 V 宽电化学窗口。9a [206] 所示。由于 LLZO 纳米线的高刚性和良好的分散性，PLLN 的拉伸强度增加到近 1.0 MPa，最大应变为 2092%。全固态 LFP/PLLN/Li 电池在 60 °C、0.5 C 条件下循环 70 次后，比容量达到 158.8 mAh g^-1；在 45 °C、0.1 C 条件下循环 80 次后，比容量达到 158.7 mAh g^-1。LLZO 纳米线在聚合物中的均匀分散显著提高了 OICSE 的离子导电性和机械强度。用 OICSE 组装的锂||锂对称电池在 60 ℃ 下稳定循环 1000 小时，且无短路现象。Li 等人以脱脂棉为模板合成了三维石榴石型 LLZO 单体，用于制造柔性固态 LLZO/PEO LiTFSI 电解质（图9b）[207]。这种 OICSE 的离子电导率达到 0.89 × 10^-4 S cm^-1 ，并且使用 Li|OICSE|SS 对 Li⁺/Li 显示出 5.5 V 的宽电化学窗口。与 LiFePO₄ 匹配的 ASSLB 具有较高的循环稳定性和速率性能。为了减少离子传导路径的曲折性，Hu 等人采用了一种新的方法来减少离子传导路径的曲折性。 以木材为模板，结合聚合物 PEO，通过自上而下的方法制造出具有高导电性多尺度排列的石榴石框架结构（图9c）[208]。该结构的离子电导率高达 1.8 × 10^-4 S cm^-1 ，在 RT 条件下具有出色的机械柔韧性。值得注意的是，离子电导率与块体电导率非常接近，石榴石/聚合物界面的影响被显著放大。低曲率石榴石木结构作为一种高导电性固态电解质，显示出巨大的潜力，为旨在设计和优化 OICSE 的研究提供了一个宝贵的模型。

Fig. 9 图 9

a Schematic illustration of an integrated LiFPO₄/CSE/Li battery [206], Copyright 2018 WILEY. b Schematic illustration for the preparation of LLZO/PEO-LiTFSI electrolyte [207] Copyright 2019 WILEY. c Schematic of multiscale aligned mesoporous garnet LLZO membrane incorporated with PEO polymer [208], Copyright 2019, American Chemical Society. d Schematic diagram of dopamine polymerization on the LLZTO surface to form a polydopamine coating and the dispersion of LLZTO particles (coated and uncoated with PDA) in PEO solution [209], Copyright 2019 Royal Society of Chemistry. e Schematic diagram of the synthesis route for grafting molecular brushes onto LLZTO surface (MB-LLZTO) [211], Copyright 2019 Royal Society of Chemistry. f Preparation process diagram of an OICSE that forms a "bridge" between polymer and ceramic phase [212], Copyright 2023 Elsevier. g Schematic diagram of tape casting and battery manufacturing of PVDF/Al LLZO film on composite electrodes [214], Copyright 2023, American Chemical Society. h Preparation method and characterization diagram of PAN/LiClO₄: LLZTO film [215], Copyright 2020, American Chemical Society
a 集成 LiFPO₄/CSE/Li 电池的示意图 [206], Copyright 2018 WILEY.b LLZO/PEO-LiTFSI 电解质的制备示意图 [207] 版权所有 2019 WILEY。c 加入 PEO 聚合物的多尺度排列介孔石榴石 LLZO 膜示意图 [208]，美国化学学会版权所有，2019 年。d 多巴胺在 LLZTO 表面聚合形成多巴胺涂层以及 LLZTO 颗粒（涂覆和未涂覆 PDA）在 PEO 溶液中的分散示意图[209]，版权所有，英国皇家化学会 2019 年。e 将分子刷接枝到 LLZTO 表面（MB-LLZTO）的合成路线示意图[211], Copyright 2019 Royal Society of Chemistry.f 在聚合物和陶瓷相之间形成 "桥梁 "的 OICSE 的制备过程图[212], Copyright 2023 Elsevier.g 复合电极上 PVDF/Al LLZO 薄膜的胶带浇铸和电池制造示意图 [214], Copyright 2023, 美国化学学会。h PAN/LiClO₄：LLZTO 薄膜 [215], Copyright 2020, 美国化学会

Improving the interfacial compatibility between nanofillers and polymers through surface modification is an effective method to enhance thermal stability and electrochemical properties. Huang and co-workers reported the modification of LLZTO nanoparticles by coating with polydopamine (PDA) [209]. Due to the dual wettability properties of dopamine on organic and inorganic materials, a strong bond was formed between LLZTO and PEO, as shown in Fig. 9d resulting in 80 wt% LLZTO uniformly dispersed in a polymer electrolyte composed of 20 wt% PEO/LiTFSI. The ionic conductivity increased from 6.3 × 10⁻⁵ S cm⁻¹ to 1.1 × 10⁻⁴ S cm⁻¹ at 30 °C after modification compared to unmodified LLZTO in PEO. Previous studies have indicated that 10–20 wt% LLZTO is well dispersed in PEO-based polymer electrolytes when LLZTO is unmodified [32, 64, 210]. Above this percolation value, particles begin to agglomerate, resulting in a decrease in ionic conductivity. Therefore, surface modification can improve the dispersibility of fillers by adding higher content fillers without agglomeration, thereby enhancing the mechanical strength and ion transport pathway of OICSEs. The surface modifying groups are usually acidic surface groups (e.g., -hydroxyl (–OH) groups), which enhance the interaction of the filler with the lithium salt and the polymer through hydrogen bonding, increasing the dissociation of the lithium salt. Or positively charged modifications (e.g., –NH₃⁺ groups), which improve the anion adsorption capacity of the filler through electrostatic interactions and promote the dissociation of the lithium salt, thus increasing the ionic conductivity and Li⁺ transference number. Li et al. employed a molecular brush modification LLZTO approach, denoted as MB-LLZTO. They utilized 1-methyl-3-trimethoxysilane imidazolium chloride (PMImCl) and incorporated MB-LLZTO into the PEO matrix to create OICSE, as illustrated in Fig. 9e [211]. The results showed that the OICSE containing 15 wt% MB-LLZTO exhibited the highest ionic conductivity of 3.11 × 10⁻⁴ S cm⁻¹ at 45 °C. This represented a significant improvement from the ionic conductivity of pristine LLZTO-CPE (9.16 × 10⁻⁵ S cm⁻¹). The all-solid-state lithium-sulfur battery with MB-LLZTO-CPE shows the highest discharge capacity of 1280 mAh g⁻¹ at low temperature and stable cycling performance (752 mAh g⁻¹ after 220 cycles). The construction of molecular brushes on the LLZTO surface may be an effective way to unlock more potential of solid polymer electrolytes. Yu et al. reduced the interfacial resistance and increased the electrochemical window by creating a "bridge" between the polymer and ceramic phases, as shown in Fig. 9f [212]. Chemical and hydrogen bonds between the polymer and ceramic phases were created, establishing ultrafast Li-ion transport channels. This structure resulted in high ionic conductivity of 3.1 × 10⁻³ S cm⁻¹ at RT, and the symmetrical Li||Li cells exhibited long-life stripping/plating behavior over 1000 h at 0.1 mA cm⁻² without short-circuiting. The LFP|PAL|Li battery shows a stable discharge capacity of 143 mAh g⁻¹ and keeps 92% capacity retention over 100 cycles with a coulombic efficiency of 99% at 0.5 C. This “bridging” strategy provides an effective way to solve high interface resistance and interface compatibility problems.
通过表面改性改善纳米填料与聚合物之间的界面相容性是提高热稳定性和电化学性能的有效方法。Huang 及其合作者报道了通过涂覆多巴胺 (PDA) 对 LLZTO 纳米颗粒进行改性[209]。如图9d所示，由于多巴胺在有机和无机材料上的双重润湿特性，LLZTO和PEO之间形成了牢固的结合，从而使80 wt%的LLZTO均匀地分散在由20 wt%的PEO/LiTFSI组成的聚合物电解质中。与 PEO 中未改性的 LLZTO 相比，改性后的离子电导率在 30 °C 时从 6.3 × 10^-5 S cm^-1 增加到 1.1 × 10^-4 S cm^-1 。以前的研究表明，当 LLZTO 未改性时，10-20 wt% 的 LLZTO 可以很好地分散在基于 PEO 的聚合物电解质中 [32、64、210]。超过这个渗滤值，颗粒就会开始团聚，导致离子传导性降低。因此，表面改性可以通过添加较高含量的填料来改善填料的分散性，而不会造成团聚，从而提高 OICSE 的机械强度和离子传输途径。表面改性基团通常为酸性表面基团（如-羟基（-OH）基团），可通过氢键增强填料与锂盐和聚合物的相互作用，增加锂盐的解离。或带正电的修饰（例如, -NH₃⁺ 基团），通过静电作用提高填料的阴离子吸附能力，促进锂盐的解离，从而提高离子电导率和锂⁺ 迁移数。Li 等人采用了分子刷修饰 LLZTO 方法，简称 MB-LLZTO。他们利用 1-甲基-3-三甲氧基硅烷咪唑氯化物（PMImCl），将 MB-LLZTO 加入 PEO 基质中，制成 OICSE，如图 9e [211] 所示。结果表明，含有 15 wt% MB-LLZTO 的 OICSE 在 45 °C 时的离子电导率最高，达到 3.11 × 10^-4 S cm^-1 。与原始 LLZTO-CPE 的离子电导率（9.16 × 10^-5 S cm^-1）相比，这是一个重大改进。含有 MB-LLZTO-CPE 的全固态锂硫电池在低温下显示出最高的放电容量（1280 mAh g^-1 ）和稳定的循环性能（220 次循环后为 752 mAh g^-1 ）。在 LLZTO 表面构建分子刷可能是发掘固体聚合物电解质更多潜力的有效方法。如图 9f [212] 所示，Yu 等人通过在聚合物和陶瓷相之间架设 "桥梁"，降低了界面电阻，增加了电化学窗口。聚合物和陶瓷相之间产生了化学键和氢键，从而建立了超快锂离子传输通道。这种结构使锂离子的离子传导率高达 3.1 × 10^-3 S cm^-1 在 RT 条件下，对称||锂电池在 0.1 mA cm^-2 条件下放电 1000 h，表现出长寿命剥离/电镀行为，且无短路现象。LFP|PAL|Li 电池显示出 143 mAh g^-1的稳定放电容量，在 0.5 C 条件下，100 次循环的容量保持率为 92%，库仑效率为 99%。

In addition to PEO, polymers like PEGDA, PVDF, PAN, and PMMA are also incorporated into ceramic fillers to create various OICSEs. Yu et al. developed PEGDA-SN-LiTFSI-LLZTO electrolytes by incorporating LLZTO nanoparticles into a PEGDA polymer matrix [213]. The OICSE achieves a high ionic conductivity of 3.1 × 10⁻⁴ S cm⁻¹ at RT, coupled with a wide electrochemical stability window of 4.7 V versus Li⁺/Li using Li|OICSE|SS. The LLZTO enhances ionic conductivity and helps suppress lithium dendrite formation. Concurrently, the PEGDA polymer ensures robust interfacial contact with the electrode. A flexible ceramic-polymer electrolyte composed of aluminum-doped garnet (Li_6.28Al_0.24La₃Zr₂O₁₂) and PVDF at an 8:2 ratio, as shown in Fig. 9g [214]. This OICSE membrane indicates a broad electrochemical window of 5.5 V versus Li⁺/Li by LSV using Li|OICSE|SS, high ionic conductivity of 5 × 10⁻⁵ S cm⁻¹, and Li⁺ transference number (0.69), outstanding mechanical strength, and thermal stability. The LFP |CPE|Li cell delivered an initial capacity of 137 mAh g⁻¹ at 0.2 C and 121 mAh g⁻¹ at 1 C with minimum resistance. Chen et al. prepared ultrathin PAN/LiClO₄: LLZTO electrolytes using a combined electrospinning/electrospraying technique, which resulted in continuous interfacial conduction channels, as illustrated in Fig. 9h [215]. The OICSE exhibited a high ionic conductivity of 1.16 × 10⁻³ S cm⁻¹ at 25 °C. Li-symmetric batteries employing this electrolyte achieved stable operation for up to 5000 h at very low overpotentials and without short-circuiting. The Li-CNT| OICSE |LNMO cell exhibits a specific capacity of 137.2 mAh g⁻¹ at a current of 0.25 C with a capacity retention of 93.0% after 180 cycles. This indicates that the OICSE reported in this work can sustain stable cycling with high voltage LNMO for high energy density lithium metal batteries. Understanding the Li⁺ ion transport mechanism in polymer ceramic systems can provide new insights into the structural design of OICSEs. The ion transport mechanism section of Chapter 3 has already been described in detail. Therefore, it will not be repeated here. Additionally, Table 6 summarizes the electrochemical properties of OICSEs with garnet-type materials.
除 PEO 外，PEGDA、PVDF、PAN 和 PMMA 等聚合物也被纳入陶瓷填料中，以制造各种 OICSE。Yu 等人在 PEGDA 聚合物基质中加入 LLZTO 纳米粒子，开发出了 PEGDA-SN-LiTFSI-LLZTO 电解质[213]。OICSE 在 RT 条件下实现了 3.1 × 10^-4 S cm^-1 的高离子电导率，同时利用 Li|OICSE|SS 实现了相对于 Li⁺/Li 4.7 V 的宽电化学稳定性窗口。LLZTO 可增强离子传导性，并有助于抑制锂枝晶的形成。同时，PEGDA 聚合物可确保与电极之间稳固的界面接触。由掺铝石榴石（Li_6.28Al_0.24La₃Zr₂O₁₂) 和 PVDF 的比例为 8:2，如图 9g [214] 所示。这种 OICSE 膜显示了一个宽广的电化学窗口，即 5.5 V，离子电导率为 5 × 10^-5 S cm^-1 ，锂⁺ 转移数（0.69），具有出色的机械强度和热稳定性。LFP |CPE|Li 电池在 0.2 摄氏度时的初始容量为 137 mAh g^-1，在 1 摄氏度时的初始容量为 121 mAh g^-1，且电阻最小。Chen et al. 利用电纺丝/电喷技术制备了超薄 PAN/LiClO₄：如图9h[215]所示，利用电纺丝/电喷雾组合技术制备了 LLZTO 电解质，从而形成了连续的界面传导通道。OICSE 在 25 °C 时的离子电导率高达 1.16 × 10^-3 S cm^-1 。采用这种电解质的锂对称电池可在极低的过电位下稳定工作长达 5000 小时，且不会出现短路现象。Li-CNT| OICSE |LNMO 电池在 0.25 C 电流下的比容量为 137.2 mAh g^-1 ，循环 180 次后容量保持率为 93.0%。这表明，这项工作中报告的 OICSE 可与高电压 LNMO 保持稳定循环，用于高能量密度锂金属电池。了解聚合物陶瓷系统中的锂⁺ 离子输运机制可为 OICSE 的结构设计提供新的见解。第 3 章的离子输运机制部分已经详细介绍。因此，此处不再赘述。此外，表6总结了具有石榴石型材料的 OICSE 的电化学特性。

Table 6 Electrochemical properties of OICSEs with garnet-type materials
表 6 含有石榴石型材料的 OICSE 的电化学特性

4.2.3 Polymer Matrix Incorporating NASICON-Type Materials
4.2.3包含 NASICON 类型材料的聚合物基质

The general structural formula for NASICON-type fast ion conductors is AM₂(PO₄)₃, where 'A' denotes a monovalent metal cation (e.g., Li⁺, Na⁺, K⁺) and 'M' signifies a tetravalent or trivalent metal cation (such as Ge⁴⁺, Al³⁺, Ti⁴⁺). Among these materials, Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) and Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) are particularly noteworthy, having garnered extensive research interest for their exceptional ionic conductivity at RT (on the order of 10⁻³ S cm⁻¹) and a broad electrochemical stability window (~ 5 V). Nevertheless, the reactivity of Ti⁴⁺ and Ge⁴⁺ with lithium metal may elevate interfacial impedance, compromising stability. Integrating polymer electrolytes has been recognized as a viable strategy to bolster interface stability and enhance the overall electrochemical performance of NASICON-type electrolytes.
NASICON 型快速离子导体的一般结构式为 AM₂(PO₄)₃, 其中 "A "表示一价金属阳离子（如Li⁺、Na⁺、K⁺），'M'表示四价或三价金属阳离子（如 Ge⁴⁺、Al³⁺、Ti⁴⁺）。在这些材料中，Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) 和 Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) 尤其值得注意、在 RT 条件下具有卓越的离子传导性（约为 10^-3 S cm^-1 ）和宽广的电化学稳定性窗口（约 5 V），因而引起了广泛的研究兴趣。不过，Ti⁴⁺ 和 Ge⁴⁺ 与锂金属的反应性可能会提高界面阻抗，从而影响稳定性。集成聚合物电解质已被认为是一种可行的策略，可增强界面稳定性并提高 NASICON 型电解质的整体电化学性能。

Wang et al. synthesized LATP-PEO hybrid electrolytes utilizing a solution casting technique. Employing electrochemical impedance spectroscopy (EIS), the optimum ionic conductivity for LATP-PEO with an EO/Li ratio of 16 was 2.631 × 10⁻⁶ S cm⁻¹ at RT [225]. By augmenting the system with lithium salts, the room-temperature ionic conductivity of PEO- LiClO₄-LAGP, with an EO/Li ratio of 8 and containing 15 wt% LAGP, was enhanced to 7.985 × 10⁻⁶ S cm⁻¹. Xing et al. developed a 3D silane-modified LATP /PVDF composite electrolyte with Li⁺-percolated conductive networks through electrostatic spinning (Fig. 10a) [226]. The 3D Si@LATP/PVDF OICSE demonstrated superior ionic conductivity of 1.06 mS cm⁻¹ at 25 °C, a large Li⁺ transference number of 0.82. The significant enhancement of the Li⁺ transference number is attributed to the positive charge of -NH₃⁺ in the polysiloxane grafted onto the LATP, which makes the surface of Si@LATP positively charged and fully exposes the Lewis acid sites of the LATP, thus enhancing the anion adsorption capacity of the LATP based on electrostatic interactions. Moreover, the nanofibrous architecture significantly enhances the strength of polymer matrix, the 3D Si@LATP/PVDF OICSE has a high tensile strength of 15.3 MPa and a wide electrochemical window of 4.86 V versus Li⁺/Li was measured through LSV using Li|OICSE|SS cell. Nevertheless, the current synthesis requires specialized equipment, posing certain limitations and prompting interest in simpler, equally effective production methods for three-dimensional, high-strength skeletal electrolytes. Fan et al. successfully developed a new and simple 3D LATP porous conductive framework using common and inexpensive NaCl powder as a sacrificial template (Fig. 10b) [227]. This approach is not only facile and low-cost but also environmentally friendly because the template can be dissolved in water, and the porosity of the 3D porous conductive framework is easily controlled (Fig. 10c). Integrating a PEO matrix resulted in a 3D LATP-PEO electrolyte with notable ionic conductivity of 7.47 × 10⁻⁴ S cm⁻¹ at 60 °C. The symmetrical Li||Li cells with this electrolyte exhibited long-life stripping/plating behavior over 1000 h at 0.2 mA cm⁻². To avoid the accumulation of particles and to improve the filler–polymer interaction, Xiong et al. engineered PMMA-coated LATP with PVDF matrix, as shown in Fig. 10d [228]. The molecular affinity between PMMA and PVDF facilitated a uniform dispersion of PMMA-coated LATP particles throughout the polymer matrix, resulting in a continuous and interconnected 3D LATP network. In addition, the enhanced affinity of LATP for the PVDF matrix and the inherent Li⁺ complexation ability of PMMA ensured straight Li⁺ conduction channels through the LATP framework and the LATP/PVDF interface. The results showed that the LATP@PMMA-PVDF electrolyte obtained a high ionic conductivity of 1.23 × 10⁻³ S cm⁻¹ and a Li⁺ transference number of 0.85 at RT. Additionally, by incorporating ionic liquid salts into the LAGP/PVDF-HFP electrolyte, as illustrated in Fig. 10e, the interfacial wettability between the solid electrolyte and active materials was significantly improved, effectively enhancing the ionic conductivity of the OICSE [229]. This compatibility with lithium metal enabled LiFePO₄ solid-state lithium batteries achieves discharge capacity as high as 157.8 mAh g⁻¹ at 0.05 C and maintains 141.3 mAh g⁻¹ after the 50th cycle with a capacity retention of 89.5%, offering a strategic and innovative approach to advancing solid-state battery technology.
Wang 等人利用溶液浇铸技术合成了 LATP-PEO 混合电解质。利用电化学阻抗谱（EIS），在 RT [225] 时，EO/Li 比率为 16 的 LATP-PEO 的最佳离子电导率为 2.631 × 10^-6 S cm^-1 。通过在系统中添加锂盐，PEO- LiClO₄-LAGP 的室温离子电导率提高到了 7.985 × 10^-6 S cm^-1 （EO/Li 比为 8，LAGP 含量为 15 wt%）。Xing 等人通过静电纺丝开发了一种三维硅烷改性 LATP /PVDF 复合电解质，其中含有锂⁺ 渗透导电网络（图10a）[226]。三维 Si@LATP/PVDF OICSE 在 25 °C 时的离子电导率高达 1.06 mS cm^-1 ，锂⁺ 转移数高达 0.82。锂⁺ 透射率的显著提高归功于接枝到 LATP 上的聚硅氧烷中的 -NH₃⁺ 正电荷、这使得 Si@LATP 表面带正电，充分暴露了 LATP 的路易斯酸位点，从而增强了 LATP 基于静电相互作用的阴离子吸附能力。此外，纳米纤维结构显著增强了聚合物基体的强度，三维 Si@LATP/PVDF OICSE 的拉伸强度高达 15.3 MPa，而且通过使用 Li|OICSE|SS 电池进行 LSV 测量，它对 Li⁺/Li 的电化学窗口宽达 4.86 V。 然而，目前的合成方法需要专门的设备，具有一定的局限性，因此人们对更简单、同样有效的三维高强度骨架电解质生产方法产生了兴趣。Fan 等人利用常见且廉价的氯化钠粉末作为牺牲模板，成功开发出了一种新型、简单的三维 LATP 多孔导电框架（图 10b) [227]。这种方法不仅简便、成本低，而且环保，因为模板可以溶解在水中，三维多孔导电框架的孔隙率也很容易控制（图10c）。整合 PEO 矩阵后，三维 LATP-PEO 电解质在 60 °C 时的离子电导率为 7.47 × 10^-4 S cm^-1 。在 0.2 mA cm^-2条件下，使用这种电解质的对称锂电池在 1000 小时内表现出长寿命剥离/电镀行为。为了避免颗粒堆积并改善填料与聚合物之间的相互作用，Xiong 等人. 设计了具有 PVDF 基质的 PMMA 涂层 LATP，如图10d [228] 所示。PMMA 和 PVDF 之间的分子亲和力促进了 PMMA 涂层 LATP 颗粒在整个聚合物基质中的均匀分散，从而形成了连续且相互连接的三维 LATP 网络。此外，LATP 与 PVDF 矩阵的亲和力增强以及 PMMA 固有的 Li⁺ 复合能力确保了 Li⁺ 通过 LATP 框架和 LATP/PVDF 界面的直通传导通道。 结果表明，LATP@PMMA-PVDF 电解质在 RT 条件下获得了 1.23 × 10^-3 S cm^-1 的高离子电导率和 0.85 的锂⁺ 转移数。此外，如图10e所示，通过在 LAGP/PVDF-HFP 电解质中加入离子液体盐，固体电解质和活性材料之间的界面润湿性得到了显著改善，从而有效提高了 OICSE 的离子导电性[229]。这种与锂金属的兼容性使 LiFePO₄ 固态锂电池在 0.05 C 时放电容量高达 157.8 mAh g^-1，并且在第 50 个循环后仍能保持 141.3 mAh g^-1 的容量，容量保持率高达 89.5%。

Fig. 10 图 10

a Schematic diagram of 3D composite fiber network reinforced CPE preparation [226], Copyright 2022 Elsevier. b Schematic diagram of 3D porous LATP framework. c SEM images of 3D porous LATP frameworks with different NaCl template mass fractions [227], Copyright 2021 Elsevier. d Schematic diagram of the synthesis process and conduction mechanism of LATP@PMMA-PVDF electrolytes [228], Copyright 2021 Elsevier. e Schematic illustration for the synthesis of OICSE [229], Copyright 2017, American Chemical Society. f Schematic diagram of LiFePO₄ | LAGP/30% PPC | Li batteries forming a LiF protective layer [230], Copyright 2019, American Chemical Society. g Schematic diagram of Li/PEO (LiTFSI)@LAGP-PEO (LiTFSI)/LiMFP batteries preparation [231], Copyright 2017, American Chemical Society. h Schematic diagram of LATP and PVDF@LATP@PVDF electrolytes at 0.1 mA cm⁻². i Cross-sectional and surface SEM images of the LATP pellet [232], Copyright 2022, American Chemical Society
a 三维复合纤维网络增强 CPE 制备示意图 [226], Copyright 2022 Elsevier.b 三维多孔 LATP 框架示意图。c 具有不同 NaCl 模板质量分数的三维多孔 LATP 框架的 SEM 图像 [227]，版权属于 2021 Elsevier。d LATP@PMMA-PVDF 电解质的合成过程和传导机制示意图[228], Copyright 2021 Elsevier.e OICSE 的合成示意图[229], Copyright 2017, American Chemical Society.f LiFePO₄ | LAGP/30% PPC | Li 电池形成 LiF 保护层的示意图[230], Copyright 2019, 美国化学会。g Li/PEO (LiTFSI)@LAGP-PEO (LiTFSI)/LiMFP 电池制备示意图[231], Copyright 2017, American Chemical Society.h LATP 和 PVDF@LATP@PVDF 电解质在 0.1 mA cm^-2 时的示意图。i LATP 粒子的横截面和表面 SEM 图像 [232]，版权 2022 年，美国化学会

To address the challenges associated with the high interfacial impedance and failure of solid-state batteries stemming from the incompatibility between NASICON-type inorganic electrolytes and lithium metal, the strategic formation of a spontaneous protective layer or the deliberate incorporation of a synthetic polymer layer presents a productive approach. Yu et al. designed a "self-sacrificing" interface through the reaction of a LiF layer deposited on a flexible LAGP/30% polypropylene carbonate (PPC) OICSE with Li metal, as shown in Fig. 10f [230]. This layer reduces the interfacial resistance between the electrolyte and the Li metal and endows the LiFePO₄/Li cell with a discharge-specific capacity of 151 mAh g⁻¹ at 0.05 C and a retention of 92.3% for 100 cycles at 55 °C. Wang et al. introduced a PEO (LiTFSI) interlayer between the LAGP-PEO CSE and lithium metal (Fig. 10g), mitigating side reactions at the interface [231]. The assembled Li-PEO (LiTFSI)/LAGP-PEO/LiMn_0.8Fe0_.2PO₄ all-solid-state battery displayed an initial discharge capacity of 160.8 mAh g⁻¹, with notable cycling stability and rate performance at 50 °C. Similarly, Tao et al. further advanced the field by implementing a PVDF buffer layer on the LAGP surface, successfully reducing the interfacial impedance (from 5789 to 271 Ω) and effectively preventing the side reactions between the Li anode and LATP [232]. The Li||Li symmetric battery exhibited an exceptionally long life of over 3000 h at 0.1 mA cm⁻² (Fig. 10h). Additionally, ASSLBs matched with LiFePO₄ indicated robust cycling stability with an initial discharge capacity of 141.1 mAh g⁻¹ and maintained 83.4% capacity after 300 cycles. SEM images in Fig. 10i confirm the uniform PVDF coating on LATP particles, suggesting favorable interfacial chemistry. The above results indicate that the interfacial modification strategy successfully protected the electrolyte and lithium metal instability. Meanwhile, it provides a helpful contribution to developing stable solid-state batteries.
为了解决因 NASICON 型无机电解质与锂金属不兼容而导致的高界面阻抗和固态电池失效问题，策略性地形成自发保护层或有意加入合成聚合物层是一种有效的方法。Yu 等人. 设计了一种 "自我牺牲 "界面，方法是将沉积在柔性 LAGP/30% 聚丙烯碳酸酯 (PPC) OICSE 上的 LiF 层与金属锂发生反应，如图10f [230] 所示。该层降低了电解质与金属锂之间的界面电阻，使 LiFePO₄/Li 电池在 0.05 C 时的放电特定容量达到 151 mAh g^-1 ，在 55 °C 下循环 100 次的保持率为 92.3%。Wang 等人在 LAGP-PEO CSE 和锂金属之间引入了 PEO（LiTFSI）夹层（图10g），减轻了界面上的副反应[231]。组装好的 Li-PEO (LiTFSI)/LAGP-PEO/LiMn_0.8Fe0_.2PO₄ 全固态电池的初始放电容量为 160.8 mAh g^-1，在 50 °C 下具有显著的循环稳定性和速率性能。同样，Tao 等人通过在 LAGP 表面实施 PVDF 缓冲层，成功地降低了界面阻抗（从 5789 Ω 降至 271 Ω），并有效地防止了锂阳极和 LATP 之间的副反应[232]，从而进一步推动了该领域的发展。 在 0.1 mA cm^-2（图 10h ）条件下，锂||锂对称电池显示出超过 3000 小时的超长寿命。此外，与 LiFePO₄ 相匹配的 ASSLB 具有强大的循环稳定性，初始放电容量为 141.1 mAh g^-1 并在 300 次循环后保持了 83.4% 的容量。图10i 中的 SEM 图像证实了 LATP 颗粒上均匀的 PVDF 涂层，表明界面化学性质良好。上述结果表明，界面改性策略成功地保护了电解质和锂金属的不稳定性。同时，它为开发稳定的固态电池做出了有益的贡献。

4.2.4 Polymer Matrix Incorporating Perovskite-Type Materials
4.2.4包含过氧化物类材料的聚合物基质

The fastest lithium-ion-conducting electrolytes are the perovskite-type La_2/3-xLi_3xTiO₃ (LLTO) and its variants. These materials are characterized by their significant A-site vacancy concentrations, facilitating efficient Li-ion migration. They exhibit a bulk conductivity of 10⁻³ S cm⁻¹ at ambient temperature, with grain-boundary conductivity ranging from 10⁻⁴ to 10⁻⁵ S cm⁻¹, comparable to traditional liquid electrolytes. Nevertheless, these perovskite-type electrolytes demonstrate a propensity for reduced cathodic stability, a drawback primarily ascribed to their reactive reduction with lithium metal (Ti⁴⁺ + Li → Ti³⁺ + Li⁺).
传导锂离子最快的电解质是包晶型 La_2/3-xLi_3xTiO₃ (LLTO) 及其变体。这些材料的特点是具有显著的 A 位空位浓度，有利于锂离子的有效迁移。在环境温度下，它们的体积电导率为 10^-3 S cm^-1 、晶界电导率介于 10^-4 到 10^-5 S cm^-1 之间，与传统的液态电解质相当。然而，这些包晶型电解质显示出阴极稳定性降低的倾向，这一缺点主要归因于它们与锂金属的反应性还原（Ti⁴⁺ + Li → Ti³⁺ + Li⁺ ）。

Analogous to polymer-garnet OICSEs, the ionic conductivity of polymer-perovskite OICSE is markedly influenced by particulate characteristics such as size, morphology, and spatial distribution. Table 7 summarizes the electrochemical properties of OICSEs with perovskite-type materials. Zhang et al. utilized the electrospinning technique to fabricate Li_0.33La_0.557TiO₃ (LLTO) nanofibers with an elevated aspect ratio. Subsequently, they incorporated these into a PEO matrix to engineer a PEO/LLTO OICSE [233]. This innovative electrolyte demonstrated an ionic conductivity of 2.4×10⁻⁴ S cm⁻¹ at RT and exhibited an impressive electrochemical window of 5 V versus Li⁺/Li in Li|OICSEs|SS cell. Nan et al. fabricated CPEs by incorporating a 3D LLTO nano-network into a PEO matrix through hot-pressing and quenching (Fig. 11a) [234]. The CPE featuring the 3D LLTO network (3D-CPE) displayed a higher ionic conductivity of 1.81×10⁻⁴ S cm⁻¹ and a wide electrochemical window of 4.5 V versus Li/Li⁺ at RT than that of the PEO-based electrolyte. This enhancement in ion transport efficiency is ascribed to the uniform distribution of interfaces between the LLTO framework and the PEO matrix, which facilitates a rapid ion transport pathway and reduces the barrier for ion hopping. With the help of the LLTO nanofiber network, the 3D-CPE exhibits a tensile strength of 16.18 MPa, Young's modulus of 0.98 GPa, elongation of over 200%, and an apparent yield point, which is attributed to the good adhesion between the matrix and filler and the strong support of the inorganic LLTO backbone. The symmetrical Li|3D-CPE|Li battery exhibited a long cycle life of over 800 h at 0.1 mA cm⁻² (Fig. 11a), indicating that the 3D-CPE film can effectively inhibit the Li dendrites growth and is a promising candidate electrolyte for flexible solid-state lithium-ion batteries. Zhao et al. examined the effects of randomly dispersed LLTO nanoparticles and vertically aligned LLTO on the enhancement of ionic conductivity in PEO/LiTFSI/LLTO electrolytes (Fig. 11b) [235]. The OICSE with Ice-LLTO-PEO-LiTFSI structure achieves a remarkable ionic conductivity of 1.3×10⁻⁴ S cm⁻¹, 2.4 orders of magnitudes higher than the mechanically mixed counterpart. The pronounced enhancement is attributed to the vertically aligned structure, which provides a contiguous and expedited network for the transport of Li⁺ ions. Furthermore, the symmetric Li||Li cell utilizing Ice-LLTO-PEO-LiTFSI OICSE demonstrates stable operation over 400 h at 0.3 mA cm⁻² (Fig. 11c), Li|OICSE|LFP full battery delivers a specific discharge capacity of 144.6 mAh g⁻¹ at 1 C at 60 °C with a high-capacity retention of 96.0% after 100 cycles, further confirming the superior electrochemical properties.
与聚合物石榴石 OICSE 类似，聚合物-透辉石 OICSE 的离子导电性明显受到颗粒特征（如大小、形态和空间分布）的影响。表7总结了具有包晶型材料的 OICSE 的电化学特性。Zhang et al.利用电纺丝技术制造出高宽比的 Li_0.33La_0.557TiO₃ (LLTO) 纳米纤维。随后，他们将这些纳米纤维掺入 PEO 基质中，设计出了 PEO/LLTO OICSE [233]。这种创新型电解质在 RT 条件下的离子电导率为 2.4×10^-4 S cm^-1 ，在 Li|OICSEs|SS 电池中对 Li⁺/Li 的电化学窗口为 5 V，令人印象深刻。Nan 等人通过热压和淬火将三维 LLTO 纳米网络融入 PEO 基体，从而制造出了 CPE（图 11a ）[234] 。与基于 PEO 的电解质相比，具有三维 LLTO 网络的 CPE（三维 CPE）在 RT 时的离子电导率高达 1.81×10^-4 S cm^-1 ，对 Li/Li⁺ 的电化学窗口宽达 4.5 V。离子传输效率的提高归因于 LLTO 框架和 PEO 基质之间界面的均匀分布，这有利于形成快速的离子传输通道，并降低了离子跳跃的障碍。在 LLTO 纳米纤维网络的帮助下，3D-CPE 的拉伸强度达到 16.18 兆帕，杨氏模量为 0.0 MPa。98 GPa，伸长率超过 200%，并有明显的屈服点，这归功于基体和填料之间良好的粘附性以及无机 LLTO 骨架的强力支撑。在 0.1 mA cm^-2条件下，对称锂|3D-CPE|锂电池的循环寿命长达 800 小时以上（图11a），表明 3D-CPE 薄膜能有效抑制锂枝晶的生长，是一种很有前途的柔性固态锂离子电池候选电解质。Zhao 等人研究了随机分散的 LLTO 纳米粒子和垂直排列的 LLTO 对提高 PEO/LiTFSI/LLTO 电解质离子电导率的影响（图11b）[235]。具有 Ice-LLTO-PEO-LiTFSI 结构的 OICSE 离子电导率高达 1.3×10^-4 S cm^-1 ，比机械混合的对应物高出 2.4 个数量级。这种明显的增强归功于垂直排列的结构，它为锂⁺ 离子的传输提供了一个连续而快速的网络。此外，利用 Ice-LLTO-PEO-LiTFSI OICSE 的对称锂离子电池在 0.3 mA cm^-2 的条件下稳定运行了 400 小时（图11c）。6 mAh g^-1 ，100 次循环后容量保持率高达 96.0%，进一步证实了其卓越的电化学特性。

Table 7 Electrochemical properties of OICSEs with perovskite-type materials
表 7 含有包晶型材料的 OICSE 的电化学特性

Fig. 11 图 11

a Schematic diagram of 3D-CPEs preparation and Li plating and stripping cycling voltage profiles for the SPE and 3D-CPE [234], Copyright 2018, American Chemical Society. b Schematic diagram of ion transport paths for OICSE with mechanically mixed LLTO and OICSE with vertically aligned LLTO framework. c Li plating and stripping cycling voltage profiles for the PEO-LiTFSI and Ice-LLTO-PEO-LiTFSI [235], Copyright 2020 Elsevier. d Schematic diagram of cross-linked polyethylene oxide solid polymer electrolyte preparation. e Schematic diagram of three-dimensional fiber network OICSE composed of nanofibers and cross-linked polyethylene oxide solid polymer [236], Copyright 2019, Donghua University. f Schematic diagram of dual semi-solid polymer electrolyte films preparation [238], Copyright 2021, American Chemical Society
a 3D-CPE 制备示意图以及 SPE 和 3D-CPE 的锂电镀和剥离循环电压曲线[234], Copyright 2018, American Chemical Society.b 机械混合 LLTO 的 OICSE 和垂直排列 LLTO 框架的 OICSE 的离子传输路径示意图。c PEO-LiTFSI 和 Ice-LLTO-PEO-LiTFSI 的镀锂和剥离循环电压曲线[235], Copyright 2020 Elsevier.d 交联聚氧化乙烯固体聚合物电解质制备示意图。e 由纳米纤维和交联聚氧化乙烯固体聚合物组成的三维纤维网络 OICSE 示意图 [236]，东华大学 2019 年版权所有。f 双半固态聚合物电解质薄膜制备示意图 [238], Copyright 2021, 美国化学会

To improve the ionic conductivity of the OICSE and reduce the large electrode/electrolyte interface impedance, Yan et al. synthesized a novel PEO-based crosslinked polymer (CLP) as a polymer matrix [236]. Figure 11d shows the crosslinking synthesis process of the CLP polymer matrix, in which poly(ethylene oxide) methyl ether acrylate (PEGMEA) monomer and poly(ethylene oxide) dimethacrylate (PEGDMA) were used as the crosslinking agents for photoinitiated polymerization. A certain amount of PEG plasticizer was added to improve the ion migration rate. LLTO nanofibers were doped into CLP matrix to form CLP-P-LLTO electrolyte (Fig. 11e), and the total ionic conductivity of CLP-P-LLTO was enhanced from 2.40 × 10⁻⁴ to 3.31 × 10⁻⁴ S cm⁻¹ at RT. The CLP-P-LLTO delivered a noteworthy specific capacity of 147 mAh g⁻¹ in the Li|LiFePO₄ battery, and no significant lithium dendrite formation was observed at the anode/electrolyte interface after 100 cycles. Chang et al. introduced a fluorine-rich intercalation (denoted as succinonitrile interlayer) based on butanedinitrile, ethylidene fluorocarbonate, and LiTFSI in an LLTO/PVDF-HFP/LiTFSI electrolyte, which successfully reduced the interface resistance and suppressed unfavorable interfacial side reactions [237]. On the Li metal electrode, the SNI-derived solid electrolyte interface (SEI) enriched with LiF and CF_x slowed the build-up of dead lithium and excess SEI. Notably, the introduction of SNI significantly reduced the hydrogen defluorination reaction of PVDF-HFP. Siyal et al. proposed an innovative strategy to address the critical issues of lithium dendritic growth and interfacial resistance in lithium metal batteries [238]. They developed a dual semi-solid-state polymer electrolyte (DSPE) membrane by incorporating NASICON-type LATP and perovskite-type LLTO nanoparticles as Li⁺ ion-conducting ceramic fillers within a PVDF matrix (Fig. 11f). The results showed that this DSPE membrane successfully reduced interfacial impedance and protected lithium dendrites in lithium metal batteries. The symmetrical cell Li|DSPE|Li exhibits excellent stability at a high current density of 1 mA cm⁻² over 1000 h, and the LiCoO₂|DSPE|Li cell reaches an initial discharge specific capacity of 145.3 mAh g⁻¹ at 0.1 C with a stable coulombic efficiency of 98% after 100 cycles. This provides a new method for preparing high-performance ASSLBs.
为了提高 OICSE 的离子导电性并降低较大的电极/电解质界面阻抗，Yan 等人合成了一种新型 PEO 基交联聚合物 (CLP) 作为聚合物基质[236]。图 11d 显示了 CLP 聚合物基体的交联合成过程，其中聚（环氧乙烷）甲基醚丙烯酸酯（PEGMEA）单体和聚（环氧乙烷）二甲基丙烯酸酯（PEGDMA）被用作光引发聚合的交联剂。为了提高离子迁移率，还添加了一定量的 PEG 增塑剂。将 LLTO 纳米纤维掺杂到 CLP 基质中形成 CLP-P-LLTO 电解质（图11e），CLP-P-LLTO 的总离子电导率从 2.40 × 10^-4 提高到 3.31 × 10^-4 S cm^-1 。在 Li|LiFePO₄ 电池中，CLP-P-LLTO 提供了 147 mAh g^-1 的显著比容量，并且在 100 次循环后，在阳极/电解质界面没有观察到明显的锂枝晶形成。Chang 等人在 LLTO/PVDF-HFP/LiTFSI 电解液中引入了基于丁二腈、亚乙基碳酸氟乙酯和 LiTFSI 的富氟插层（表示为琥珀腈夹层），成功降低了界面电阻并抑制了不利的界面副反应[237]。在锂金属电极上，富含 LiF 和 CF_x 的 SNI 衍生固体电解质界面（SEI）减缓了死锂和过量 SEI 的积累。值得注意的是，SNI 的引入大大减少了 PVDF-HFP 的氢脱氟反应。Siyal 等人 提出了一种创新战略来解决锂金属电池中锂枝晶生长和界面电阻的关键问题[238]。他们将 NASICON 型 LATP 和 perovskite 型 LLTO 纳米粒子作为锂⁺ 离子传导陶瓷填料加入 PVDF 基体中，开发出一种双半固态聚合物电解质（DSPE）膜（图11f）。结果表明，这种 DSPE 膜成功地降低了界面阻抗，保护了锂金属电池中的锂枝晶。对称电池 Li|DSPE|Li 在 1 mA cm^-2 的高电流密度下显示出超过 1000 h 的优异稳定性，而 LiCoO₂|DSPE|Li 电池在 0.1 C 下的初始放电比容量达到 145.3 mAh g^-1 ，100 次循环后库仑效率稳定在 98%。这为制备高性能 ASSLB 提供了一种新方法。

Table 8 summarizes the ionic conductivity, advantages, and disadvantages of active fillers. In OICSEs, the active material not only promotes lithium-ion transport by inhibiting the crystallinity of the polymer matrix but also participates directly in lithium-ion conduction. Therefore, choosing the active material requires comprehensive consideration of the following factors: ionic conductivity, chemical stability, mechanical properties, and compatibility with electrode materials. Optimization of these factors can achieve the best performance and sustainability of OICSEs.
表8总结了活性填料的离子传导性、优点和缺点。在 OICSE 中，活性材料不仅能通过抑制聚合物基体的结晶性来促进锂离子传输，还能直接参与锂离子传导。因此，选择活性材料需要综合考虑以下因素：离子传导性、化学稳定性、机械性能以及与电极材料的兼容性。优化这些因素可实现 OICSE 的最佳性能和可持续性。

Table 8 Summarize the ionic conductivity and advantages and disadvantages of active fillers
表 8 总结活性填料的离子导电性和优缺点

5 Advanced Characterization Method for OICSEs
5 OICSE 的高级特征描述方法

As all-solid-state lithium metal batteries and other sophisticated energy storage systems advance, there is a burgeoning need for comprehensive research into composite electrolytes. This necessitates more intricate and nuanced characterization methods to reveal their structural complexities, intrinsic properties, and interfacial interactions. Therefore, some advanced material characterization techniques have important background and application value in OICSE research.
随着全固态锂金属电池和其他先进储能系统的发展，对复合电解质的综合研究需求急剧增加。这就需要更复杂、更细致的表征方法来揭示其结构的复杂性、内在特性和界面相互作用。因此，一些先进的材料表征技术在 OICSE 研究中具有重要的背景和应用价值。

5.1 Solid-State NMR Spectroscopy and Magnetic Resonance Imaging
5.1固态 NMR 光谱和磁共振成像

Solid-state NMR and MRI techniques are non-destructive, quantitative, and qualitative. Over the past decades, solid-state NMR techniques have been widely used to study the structure and chain segment motions of composite electrolytes, polymer electrolytes, and polymer gel electrolytes [247]. The combination of magic angle rotation and broadband decoupling techniques has enabled high-resolution solid-state NMR spectroscopy, allowing the study of ionic interactions at the molecular level as well as information about the spatial proximity of functional groups. MRI is a powerful method for visualizing materials by encoding nuclear spin positions through magnetic field gradients, and in-situ MRI studies have contributed to the understanding of fundamental phenomena related to cell performance and failure mechanisms. Then, the application of solid-state NMR and MRI to the study of composite electrolytes is described.
固态核磁共振和磁共振成像技术具有非破坏性、定量和定性的特点。过去几十年来，固态核磁共振技术被广泛用于研究复合电解质、聚合物电解质和聚合物凝胶电解质的结构和链段运动[247]。魔角旋转和宽带解耦技术的结合实现了高分辨率固态核磁共振光谱，从而可以研究分子水平的离子相互作用以及功能基团的空间邻近性信息。核磁共振成像通过磁场梯度对核自旋位置进行编码，是一种可视化材料的强大方法，原位核磁共振成像研究有助于了解与细胞性能和失效机制有关的基本现象。然后，介绍了固态核磁共振和磁共振成像在复合电解质研究中的应用。

Solid-state NMR spectroscopy is a formidable investigative technique for probing the local structural environments and the dynamics process of lithium ions within ASSLBs. Its high-resolution capabilities allow it to distinguish between lithium ions in different structural environments in the OICSE, including inorganic, polymer, and interface. The ⁶Li-⁷Li isotope tracer technique enables the revelation of Li-ion transport pathways, details of which have been presented in the chapter on ion conduction mechanisms. Additionally, 2D exchange spectroscopy (EXSY) is employed to investigate ion exchange interactions between different phases. The ⁷Li NMR spectra (Fig. 12a) demonstrate the different Li-ion environments. Specifically, the resonance at − 1.2 ppm indicates Li in the polymer matrix, whereas the resonance at 0.8 ppm is representative of the Li in the LLZO [248]. The ¹⁹F NMR spectra show only a signal, suggesting a lack of interaction between the TFSI⁻ -anion and the LLZO surface. In addition, the ⁷Li 2D NMR EXSY spectra obtained at different mixing times and displayed in Fig. 12b, especially at a mixing time of 0.6 s, where the appearance of the cross-peaks further confirms the chemical exchange of lithium ions across the PEO (LiTFSI) and LLZO phases. Wagemaker et al. employed 2D ¹H-¹H nuclear Overhauser effect spectroscopy (NOESY) to understand the function of ionic liquids (ILs) in facilitating the activation of the LiTFSI-PEO-Li₆PS₅Cl interface (Fig. 12c) [249]. The observation of cross-peaks between EMIM-TFSI and LiTFSI-PEO at comparable mixing times indicates a lack of specific orientation for EMIM-TFSI relative to PEO, which corroborates their compatibility and the dynamics of EMIM-TFSI within the composite matrix. For HSE-PP13, as shown in Fig. 12c, the prompt manifestation of ¹H–¹H correlations between the ¹H resonances at the 'a' and 'b' positions on the piperidine ring of PP13-TFSI and the –OCH₂– protons of PEO at abbreviated mixing times suggests a more interactive interface between these components. Notably, these ring protons are located farthest from the bulky propyl and methyl groups attached to the N atom on the piperidine ring. This observation suggests that the positively charged N atom on the piperidine ring and its associated functional groups are positioned away from the PEO segments. The authors subsequently probed the interfacial environment of the two OICSEs employing 2D ¹H–⁶Li HETCOR spectroscopy. For HSE-EMIM, pronounced correlation signals between PEO and LiTFSI were detected, reflecting the effective solvation of EMIM within the PEO matrix. Conversely, the HSE-PP13 electrolyte exhibited no correlation between PEO and LiTFSI or decomposed Li₆PS₅Cl components, indicating a lack of homogeneous miscibility between PP13 and PEO. Further analysis of the PEO-Li₆PS₅Cl interface was conducted using ¹H–⁷Li cross-polarization (CP) experiments, which revealed the proximity of protons to both HSE-PP13 and HSE-EMIM near the Li₆PS₅Cl interface.
固态核磁共振光谱是一种强大的研究技术，可用于探测 ASSLB 内的局部结构环境和锂离子的动力学过程。它的高分辨率功能使其能够区分 OICSE 中不同结构环境下的锂离子，包括无机、聚合物和界面。⁶锂⁷锂同位素示踪技术能够揭示锂离子的传输路径，详细内容已在离子传导机制一章中介绍。此外，还采用了二维交换光谱（EXSY）来研究不同相之间的离子交换相互作用。⁷Li NMR 光谱（图12a）显示了不同的锂离子环境。具体来说，- 1.2 ppm 处的共振表示聚合物基质中的锂，而 0.8 ppm 处的共振则代表 LLZO [248]中的锂。¹⁹F NMR 光谱只显示了一个信号，表明 TFSI^- - 阴离子与 LLZO 表面之间缺乏相互作用。此外，图12b 显示了在不同混合时间下获得的 ⁷Li 2D NMR EXSY 光谱，特别是在混合时间为 0.6 秒时，交叉峰的出现进一步证实了锂离子在 PEO（LiTFSI）和 LLZO 相之间的化学交换。Wagemaker 等人 采用二维¹H-¹H核奥弗霍塞尔效应光谱（NOESY）来了解离子液体（ILs）在促进 LiTFSI-PEO-Li₆PS₅Cl 界面活化方面的功能（图.12c）[249]。在混合时间相当的情况下，观察到 EMIM-TFSI 和 LiTFSI-PEO 之间的交叉峰，表明 EMIM-TFSI 相对于 PEO 没有特定的取向，这证实了它们的兼容性以及 EMIM-TFSI 在复合基质中的动态性。至于 HSE-PP13，如图所示。12c、PP13- TFSI 的哌啶环上 "a "和 "b "位置的 ¹H-¹H 相互关系的迅速表现。TFSI 和 PEO 的 -OCH₂- 质子在较短的混合时间内发生共振，表明这些成分之间的相互作用更加密切。值得注意的是，这些环状质子距离哌啶环上 N 原子上连接的笨重丙基和甲基最远。这一观察结果表明，哌啶环上带正电荷的 N 原子及其相关官能团的位置远离 PEO 区段。作者随后采用二维 ¹H-⁶Li HETCOR 光谱探测了两种 OICSE 的界面环境。对于 HSE-EMIM，检测到了 PEO 和 LiTFSI 之间明显的相关信号，这反映了 EMIM 在 PEO 基质中的有效溶解。 相反，HSE-PP13 电解液中的 PEO 和 LiTFSI 或分解的 Li₆PS₅Cl 成分之间没有相关性，这表明 PP13 和 PEO 之间缺乏均匀的混溶性。利用 ¹H-⁷Li 交叉极化 (CP) 实验对 PEO-Li₆PS₅Cl 界面进行了进一步分析、这些实验揭示了在 Li₆PS₅Cl 界面附近，质子与 HSE-PP13 和 HSE-EMIM 都很接近。

Fig. 12 图 12

a ⁷Li MAS NMR spectra of PEO(LiTFSI)-LLZO OICSE. b ⁷Li 2D EXSY NMR spectrum with mixing times of 0.0001 s and 0.6 s, respectively [248], Copyright 2019, American Chemical Society. c 2D ¹H–¹H NOESY spectra of the mixtures of LiTFSI-PEO-Li₆PS₅Cl with PP13-TFSI ILs measured with t_mix of 0.001, 0.01 and 0.1 s. [249], Copyright 2022 Marnix Wagemake. d ⁷Li 3D MRI images of the electrochemically cycled Li₁₀GeP₂S₁₂ and PEO-coated Li₁₀GeP₂S₁₂ electrolyte. e Histograms of normalized Li density at different depths of the cycled Li₁₀GeP₂S₁₂ and PEO-coated Li₁₀GeP₂S₁₂ electrolyte, respectively [250], Copyright 2018, American Chemical Society
a⁷PEO(LiTFSI)-LLZO OICSE 的 Li MAS NMR 光谱。b⁷Li 2D EXSY NMR 光谱，混合时间分别为 0.0001 秒和 0.6 秒[248], Copyright 2019, American Chemical Society.c LiTFSI-PEO-Li 混合物的二维 ¹H-¹H NOESY 光谱₆PS₅Cl 与 PP13-TFSI IL 的混合物的 NOESY 光谱，测量 t_mix 0.001, 0.01 and 0.1 s. [249], Copyright 2022 Marnix Wagemake.d⁷Li 电化学循环 Li₁₀GeP₂S₁₂ 和 PEO 涂层 Li₁₀GeP₂S₁₂ 电解质。e Li₁₀GeP₂S₁₂ 和 PEO 涂层锂₁₀GeP₂S₁₂ 电解质不同深度的归一化锂密度、分别 [250], Copyright 2018, 美国化学学会

MRI, a non-invasive imaging technique, has recently been adapted for solid-state lithium metal battery applications. Hu et al. utilized 3D ⁷Li MRI images to capture the edge views of Li₁₀GeP₂S₁₂ and PEO-coated Li₁₀GeP₂S₁₂ electrolytes (Fig. 12d) [250]. This approach was employed to investigate the lithium distribution within symmetric battery cells after cycling, providing insights into the spatial dynamics of lithium ions during battery operation. The results indicate a localized lithium depletion at the interfacial region, exacerbating the non-uniformity of lithium-ion distribution. Quantitative 3D ⁷Li MRI imaging revealed substantial lithium-ion depletion within the top and bottom layers of the cycled images, demonstrating significant Li-ion losses in the top and bottom layers of cycled Li₁₀GeP₂S₁₂ particles, with a more acute deficit observed in the top layer. In comparison, the PEO-coated Li₁₀GeP₂S₁₂ electrolyte exhibited a diminished and more evenly distributed lithium loss across both the top and bottom interfaces. Upon examination of the histogram scatter plots detailing lithium content (Fig. 12e), the researchers discerned a non-uniform distribution of lithium in the top and bottom layers of the uncoated samples. Notably, applying a PEO coating mitigated this loss and uneven distribution of lithium ions.
核磁共振成像是一种无创成像技术，最近已被应用于固态锂金属电池。Hu 等人利用 3D ⁷Li利用三维 ⁷Li MRI 图像捕捉了 Li₁₀GeP₂S₁₂ 和 PEO 包覆的 Li₁₀GeP₂S₁₂ 电解质（图 2）。12d）[250]。采用这种方法研究了循环后对称电池单元内的锂分布情况，从而深入了解了电池运行期间锂离子的空间动态。结果表明，界面区域存在局部锂耗竭，加剧了锂离子分布的不均匀性。定量三维 ⁷Li MRI 成像显示，循环图像的顶层和底层存在大量锂离子损耗、这表明循环锂₁₀GeP₂S₁₂ 粒子的顶层和底层都有大量锂离子损耗，其中顶层的损耗更为严重。相比之下，PEO 涂层的 Li₁₀GeP₂S₁₂ 电解质在顶层和底层界面上的锂损耗都有所减少，且分布更均匀。在对锂含量的柱状散点图（图12e）进行详细检查后，研究人员发现锂在未涂层样品的顶层和底层的分布并不均匀。值得注意的是，应用 PEO 涂层后，锂离子的损失和分布不均匀的现象得到了缓解。

MRI provides intricate insights into the internal structure and interfacial characteristics of OICSEs but still faces many challenges. Primarily, the OICSEs consist of multiple components, including polymers, fillers, interface, solvents, etc., and the MRI signals of these different components may overlap, leading to complex and difficult interpretation of imaging results. Furthermore, investigating microscopic structural details and interfacial attributes within OICSEs requires high-resolution MRI, where the signal is widened through various interactions. However, the existing MRI techniques may not satisfy the requirements for the desired high resolution. Additionally, the high electric and strong magnetic fields generated under battery operating conditions may interfere with MRI imaging, affecting imaging quality and accuracy. Although MRI has a wide range of application prospects in the field of OICSEs, a series of technical difficulties, including signal separation, resolution enhancement, and interference elimination, must be overcome to achieve more accurate and detailed OICSE imaging. To improve the resolution of in-situ NMR techniques for solid-state lithium metal batteries, several aspects should be considered: (1) To achieve simultaneous NMR acquisition while the battery is electrochemically cycling, in-situ NMR requires home-made cells that are adapted to the NMR coil and signal accumulation; (2) To improve the NMR techniques for high efficiency and high spectral resolution; (3) To develop a stronger pulsed field gradient to achieve better spatial resolution in imaging and diffusion determination within the composite electrolyte or polymer electrolyte.
磁共振成像可深入了解 OICSE 的内部结构和界面特性，但仍面临许多挑战。首先，OICSE 由多种成分组成，包括聚合物、填料、界面、溶剂等，这些不同成分的磁共振成像信号可能会重叠，导致成像结果的解释复杂而困难。此外，研究 OICSE 的微观结构细节和界面属性需要高分辨率磁共振成像，其中信号会通过各种相互作用而扩大。然而，现有的磁共振成像技术可能无法满足所需的高分辨率要求。此外，电池工作条件下产生的高电场和强磁场可能会干扰磁共振成像，影响成像质量和精度。虽然核磁共振成像在 OICSE 领域具有广泛的应用前景，但要实现更精确、更细致的 OICSE 成像，必须克服信号分离、分辨率增强和干扰消除等一系列技术难题。为了提高固态锂金属电池原位 NMR 技术的分辨率，应考虑以下几个方面：（1）实现电池电化学循环时的同步 NMR 采集，原位 NMR 需要与 NMR 线圈和信号积累相适应的自制电池；（2）改进 NMR 技术，以实现高效率和高光谱分辨率；（3）开发更强的脉冲场梯度，以在复合电解质或聚合物电解质内实现更好的成像和扩散测定空间分辨率。

5.2 Time-of-Flight Secondary Ion Mass Spectrometry
5.2飞行时间二次离子质谱法

TOF–SIMS is a highly sensitive technique for analyzing surface characteristics and elemental compositions. It generates secondary ions by bombarding the sample surface with ions and then obtains information about the chemical composition, molecular structure, and distribution of elements by measuring the flight time of these secondary ions. TOF–SIMS is widely used for the detailed examination and characterization of the chemical composition of the electrolyte/electrode interface due to its desirable properties such as high spatiotemporal and mass resolution. It is particularly suitable for studying the dynamic evolution of electrolyte/electrode surface species such as reaction products and reaction intermediates. This technique can provide a multi-dimensional characterization of the electrolyte/electrode interface and thus reveal electrochemical reaction mechanisms.
TOF-SIMS 是一种用于分析表面特征和元素组成的高灵敏度技术。它通过用离子轰击样品表面产生二次离子，然后通过测量这些二次离子的飞行时间来获取有关化学成分、分子结构和元素分布的信息。TOF-SIMS 具有高时空分辨率和质量分辨率等理想特性，因此被广泛用于详细检查和表征电解质/电极界面的化学成分。它尤其适用于研究电解质/电极表面物种（如反应产物和反应中间产物）的动态演变。该技术可对电解质/电极界面进行多维表征，从而揭示电化学反应机制。

Goodenough et al. employed depth profiling and cross-sectional imaging via TOF–SIMS to investigate the interface between Li anode and CPE-25LZP electrolytes [85]. Figure 13a illustrates the surface concentration of CsLi₂P⁻ and Li₂ZrO₄⁻ species, using Zr⁻ as an indicator for the bulk solid electrolyte after cycling in a Li/Li symmetric cell. The 3D representation of the sputtered volume, shown in Fig. 13b, illustrates the spatial distribution of CsLi₂P⁻ and Zr⁻ signals. Significantly, beyond the surface concentration of CsLi₂P⁻, a fragmented distribution of both CsLi₂P⁻ and Zr⁻ ions is evident, indicating the particulate nature of the solid electrolyte. Figure 13c displays a comparative analysis of depth profiles for CsLi₂P⁻ and Li₂ZrO₄⁻ in three states: the fresh composite membrane, the composite membrane post-lithium metal interaction, and the composite membrane after cycling in Li||Li symmetric cell. The data reveal a significant increase in CsLi₂P⁻ and Li₂ZrO₄⁻ concentrations at the surface of membranes that have either been cycled or exposed to lithium compared to the fresh membrane. For a direct examination of the chemical composition along the Li/solid electrolyte interface, the authors conducted cross-sectional mapping with high lateral resolution, as depicted in Fig. 13d. This mapping identified the presence of CsLi₂P⁻ and Li₂ZrO₄⁻ species at the interface, substantiating the particulate character of the solid electrolyte at the micrometer level.
Goodenough 等人通过 TOF-SIMS 采用深度剖面分析和横截面成像来研究锂阳极和 CPE-25LZP 电解质之间的界面 [85] 。图 13a 显示了 CsLi₂P^- 和 Li₂ZrO₄^- 物种的表面浓度、使用 Zr^- 作为锂/锂对称电池循环后块状固体电解质的指示剂。图 13b 中所示的溅射体积的三维表示法说明了 CsLi₂P^- 和 Zr^- 信号的空间分布。值得注意的是，在 CsLi₂P^- 的表面浓度之外、CsLi₂P^- 和 Zr^- 离子明显呈碎片状分布，表明固体电解质具有微粒性质。图 13c 显示了 CsLi₂P^- 和 Li₂ZrO₄^- 在三种状态下的深度剖面比较分析：新复合膜、锂金属相互作用后的复合膜以及在锂||锂对称电池中循环后的复合膜。 数据显示，在循环或暴露于锂的膜表面，CsLi₂P^- 和 Li₂ZrO₄^- 与新鲜膜相比，经过循环或接触锂的膜表面的锂浓度。为了直接检查锂/固体电解质界面的化学成分，作者进行了横向分辨率较高的截面绘图，如图13d所示。该制图确定了界面上存在 CsLi₂P^- 和 Li₂ZrO₄^- 物种、证实了固体电解质在微米级的颗粒特性。

Fig. 13 图 13

a Normalized TOF–SIMS depth profiles of CsLi₂P⁻, Li₂ZrO₄⁻, and Zr⁻, representing Li₃P and Li₈ZrO₆ reacted species, and bulk LiZr₂(PO₄)₃, respectively. b 3D view of the sputtered volume in panel a. c A direct comparison of CsLi₂P⁻ and Li₂ZrO₄⁻, depth profiles obtained from the fresh composite membrane, the composite membrane after interaction with lithium metal, and the composite membrane after cycling the Li/Li symmetric cell. d TOF–SIMS high-resolution secondary ion maps of a Li/electrolyte cross-section [85], Copyright 2020, American Chemical Society. e HAADF-TEM images of PAN/LiClO₄ and the PAN/LiClO₄: LLZTO and corresponding EELS element concentration distribution map. f EELS spectra of selected regions of organic particle phase, organic/organic interface and polymer phase, polymer/inorganic interface [215], Copyright 2020, American Chemical Society
a CsLi₂P^- 的归一化 TOF-SIMS 深度剖面、Li₂ZrO₄^-, 和 Zr^-、代表 Li₃P 和 Li₈ZrO₆ 反应物种、和块状 LiZr₂(PO₄)₃ 分别发生反应。b 面板 a 中溅射体积的三维视图。c CsLi₂P^- 和 Li₂ZrO₄^- 的直接比较、从新鲜复合膜、与金属锂相互作用后的复合膜以及锂/锂对称电池循环后的复合膜上获得的深度剖面图。d 锂/电解质横截面的 TOF-SIMS 高分辨率二次离子图[85], Copyright 2020, American Chemical Society.e PAN/LiClO₄ 的 HAADF-TEM 图像和 PAN/LiClO₄：LLZTO 和相应的 EELS 元素浓度分布图。f 有机颗粒相、有机/有机界面和聚合物相、聚合物/无机界面选定区域的 EELS 光谱 [215]，2020 年美国化学学会版权所有。

TOF–SIMS provides unprecedented spatial, temporal, and mass resolution for monitoring electrochemical processes. However, achieving the goal of visualizing complex and dynamic multiphase electrochemical processes remains a major challenge. TOF–SIMS has unprecedented high mass resolution and high spatial resolution in monitoring electrochemical processes, but achieving the goal of visualizing complex and dynamic multiphase electrochemical processes remains challenges. TOF–SIMS requires a high vacuum environment to ensure the long free range of secondary ions, which poses significant challenges for complex multiphase interfaces (including liquid and solid interfaces). Therefore, there is a need to develop advanced measurement methods and vacuum-compatible electrochemical microfluidic devices to better understand dynamic electrochemical processes. In addition, the high energy of the primary ion beam can damage interfacial species, affecting the accuracy of analytical results. New primary ion sources need to be developed to improve the yield and mass resolution of secondary ions with both spatial and temporal resolution.
TOF-SIMS 为监测电化学过程提供了前所未有的空间、时间和质量分辨率。然而，实现复杂和动态多相电化学过程可视化的目标仍然是一项重大挑战。TOF-SIMS 在监测电化学过程方面具有前所未有的高质量分辨率和高空间分辨率，但实现复杂和动态多相电化学过程可视化的目标仍是一大挑战。TOF-SIMS 需要高真空环境来确保二次离子的长自由程，这给复杂的多相界面（包括液体和固体界面）带来了巨大挑战。因此，需要开发先进的测量方法和真空兼容的电化学微流控装置，以更好地了解动态电化学过程。此外，原离子束的高能量会破坏界面物种，影响分析结果的准确性。需要开发新的一级离子源，以提高二级离子的产率和质量分辨率，同时兼顾空间和时间分辨率。

5.3 High-Angle Annular Dark-Field Scanning Transmission Electron Micrographs and Electron Energy Loss Spectroscopy
5.3高角环形暗场扫描透射电子显微镜和电子能量损失光谱仪

Chen et al. utilized HAADF-STEM and EELS techniques to confirm that lithium preferentially accumulates at polymer/polymer and polymer/inorganic interfaces [215]. As shown in Fig. 13e, the Li element accumulation was observed at the periphery of PAN fiber through STEM-EELS Li K-edge mapping, further verified by EELS spectroscopy at both the PAN fiber interfaces and inner regions. The EELS spectra reveal that lithium-enriched areas surround LLZTO nanoparticles. In the EELS spectra obtained from the LLZTO region (region 1), the broad edge is observed in the 50–80 eV (Fig. 13f), lacking distinctive features. By contrast, the La-N_4,5 edge appears at approximately 110 eV, indicating a disordered chemical environment for the Li ions in LLZTO. Conversely, the spectra from the interfacial region (region 2) exhibit a more defined double-peak characteristic of the Li K-edge, suggesting a more homogeneous coordination environment. Consequently, high-resolution transmission electron microscopy (HR-TEM) imaging via HAADF-STEM facilitates the visualization of the microstructure and component distribution within the material. This approach enables the observation of the distribution, morphology, and interfaces of various components in the material, thereby enhancing our understanding of the internal structure of the composite electrolyte. Combining with EELS to analyze the elemental composition and electronic structure of material contributes to optimizing the design and performance enhancement of the composite electrolyte.
Chen 等人利用 HAADF-STEM 和 EELS 技术证实，锂元素优先在聚合物/聚合物和聚合物/无机物界面聚集[215]。如图13e 所示，通过 STEM-EELS Li K-edge 图谱观察到锂元素在 PAN 纤维外围聚集，并通过 PAN 纤维界面和内部区域的 EELS 光谱进一步验证。EELS 光谱显示，LLZTO 纳米粒子周围是锂富集区。在 LLZTO 区域（区域 1）获得的 EELS 光谱中，可以观察到 50-80 eV 的宽边（图13f），缺乏明显特征。相比之下，La-N_4,5 边缘出现在大约 110 eV 处，表明 LLZTO 中的锂离子处于无序的化学环境中。相反，界面区域（区域 2）的光谱显示出更清晰的锂 K 边双峰特征，表明配位环境更均匀。因此，通过 HAADF-STEM 进行高分辨率透射电子显微镜（HR-TEM）成像有助于观察材料内部的微观结构和成分分布。这种方法可以观察材料中各种成分的分布、形态和界面，从而加深我们对复合电解质内部结构的理解。结合 EELS 分析材料的元素组成和电子结构有助于优化复合电解质的设计并提高其性能。

HAADF-STEM can provide high-resolution images at the sub-nanometer scale to observe the nanostructures and interfaces in composite electrolytes. Through electron tomography, HAADF-STEM realizes three-dimensional reconstruction of composite electrolyte materials, which helps to study their internal structure and morphology. Combined with EELS, HAADF-STEM can perform elemental distribution and chemical state analysis, providing detailed information about the electronic structure and chemical bonding composition in composite electrolyte materials. However, high-energy electron beams can cause damage to some sensitive materials (e.g., organic or some inorganic complexes), resulting in structural changes or decomposition that may affect the observation results. Since the imaging area is very small, the results may not be representative of the homogeneity and macroscopic properties of the entire composite electrolyte material. Therefore, a more comprehensive understanding of the properties of composite electrolyte materials can be obtained by combining it with other characterization methods.
HAADF-STEM 可提供亚纳米尺度的高分辨率图像，以观察复合电解质中的纳米结构和界面。通过电子断层扫描，HAADF-STEM 实现了复合电解质材料的三维重建，有助于研究其内部结构和形态。HAADF-STEM与EELS相结合，可以进行元素分布和化学态分析，提供复合电解质材料中电子结构和化学键组成的详细信息。但是，高能电子束会对一些敏感材料（如有机物或某些无机复合物）造成损伤，导致结构变化或分解，从而影响观测结果。由于成像区域非常小，结果可能无法代表整个复合电解质材料的均匀性和宏观特性。因此，结合其他表征方法可以更全面地了解复合电解质材料的特性。

5.4 Small-Angle X-Ray Scattering (SAXS)
5.4小角 X 射线散射（SAXS）

Li et al. have thoroughly investigated the interaction between different lithium salts (LiFSI and LiTFSI), LLZO, and PEO and the effect on the nanostructure and ion transport behavior by SAXS [251]. The SAXS curves of pure PEO, PEO/LiFSI, PEO/LiTFSI, PEO/LiTFSI/LLZO at 25 and 60 °C are shown in Fig. 14a, b. At 25 and 60 °C, pure PEO exhibits first-order and second-order scattering peaks (red arrows) characteristic of the periodic layered structure formed by PEO in spherical crystals. In PEO/LiFSI, the SAXS curves show scattering peaks like pure PEO, but there are additional scattering features (black arrows) associated with the spherical clusters of LiFSI (Fig. 14a). The average radii of LiFSI clusters in the PEO/LiFSI electrolyte were about 8.5 and 8.7 nm at 25 and 60 °C, while the localized volume fractions were 0.35 and 0.28, respectively, and the localized volume fractions at 60 °C indicated that some LiFSI clusters dissolved and diffused into the amorphous PEO phase. In PEO/LiTFSI, on the other hand, the first and second peaks completely disappeared at 60 °C, indicating that LiTFSI clusters were completely dissolved in the PEO matrix. Therefore, it can be assumed that LiTFSI is more easily dissolved in PEO than LiFSI. Comparing the SAXS curves of PEO/LiTFSI and PEO/LiTFSI/LLZO (Fig. 14b), it is found that the scattering intensity of PEO/LiTFSI/LLZO is significantly increased in the low Q region, which is attributed to the addition of the micrometer-sized LLZO, whose size is beyond the measurable range of SAXS. In the higher Q region, the SAXS curves almost overlapped, indicating that the addition of LLZO did not change the microstructure of PEO and LiTFSI.
Li等人通过SAXS[251]深入研究了不同锂盐（LiFSI和LiTFSI）、LLZO和PEO之间的相互作用及其对纳米结构和离子传输行为的影响。图14a、b 显示了纯 PEO、PEO/LiFSI、PEO/LiTFSI、PEO/LiTFSI/LLZO 在 25 和 60 °C 时的 SAXS 曲线。在 PEO/LiFSI 中，SAXS 曲线显示的散射峰与纯 PEO 相似，但存在与球形 LiFSI 簇相关的额外散射特征（黑色箭头）（图 14a）。PEO/LiFSI 电解质中的 LiFSI 团簇在 25 和 60 °C 时的平均半径分别约为 8.5 和 8.7 nm，而局部体积分数分别为 0.35 和 0.28，60 °C 时的局部体积分数表明一些 LiFSI 团簇溶解并扩散到无定形的 PEO 相中。而在 PEO/LiTFSI 中，第一和第二个峰在 60 °C 时完全消失，表明 LiTFSI 簇完全溶解在 PEO 基体中。因此，可以认为 LiTFSI 比 LiFSI 更容易溶解在 PEO 中。比较 PEO/LiTFSI 和 PEO/LiTFSI/LLZO 的 SAXS 曲线（图 14b）可以发现，PEO/LiTFSI/LLZO 的散射强度在低 Q 值区显著增加，这是因为加入了微米级的 LLZO，而 LLZO 的尺寸超出了 SAXS 的测量范围。在较高的 Q 值区域，SAXS 曲线几乎重叠，这表明 LLZO 的加入并没有改变 PEO 和 LiTFSI 的微观结构。

Fig. 14 图 14

a SAXS curves of the pristine PEO (without Li salts) and PEO/LiFSI electrolytes at 25 and 60 °C. b SAXS curves of PEO/LiTFSI/LLZO were multiplied by 1.07 (~ 1/0.93) to normalize the scattering intensity for the less fraction of PEO/LiTFSI due to the added 0.07 (7%) LLZO [251] Copyright 2024, American Chemical Society. c SEM cross-sectional view of p-LATP, 3D reconstruction image of p-LATP and corresponding 2D sliced images from x–y, x–z plane [252] Copyright 2021, Wiley‐VCH GmbH. d In-situ c -AFM characterization of Li-ion migration in pure PEO(LiClO₄) and 50 wt% LLZO-PEO(LiClO₄) at 55 °C. e In-situ c-AFM characterization of Li-ions migration in 75 wt% LLZO-PEO(LiClO₄) at 30 and 55 °C. f c-AFM current curve at grain boundaries, where grain boundary 1 and grain boundary 2 [253] Copyright 2021 Elsevier B.V
a 原始 PEO（不含锂盐）和 PEO/LiFSI 电解质在 25 和 60 °C 时的 SAXS 曲线。b PEO/LiTFSI/LLZO 的 SAXS 曲线乘以 1.07 (~ 1/0.93)，以归一化因添加 0.07 (7%) LLZO 而导致 PEO/LiTFSI 分数减少时的散射强度 [251] 版权所有，美国化学会 2024 年。c p-LATP 的 SEM 截面图、p-LATP 的 3D 重建图像以及 x-y、x-z 平面的相应 2D 切片图像 [252] 版权所有 2021 年，Wiley-VCH GmbH。d 55 °C下纯 PEO（LiClO₄ ）和 50 wt% LLZO-PEO（LiClO₄ ）中锂离子迁移的原位 c -AFM 表征。 e 30 和 55 °C 时 75 wt% LLZO-PEO(LiClO₄) 中锂离子迁移的原位 c-AFM 表征。f 晶界处的 c-AFM 电流曲线，其中晶界 1 和晶界 2 [253] 版权所有 2021 Elsevier B.V

The analysis demonstrates the powerful application of SAXS in studying microstructures and interactions in polymer electrolyte or composite electrolyte systems. However, SAXS is suitable for studying structures in the range from 1 to 100 nm, and its resolution is significantly reduced for very small atomic-scale structures or larger micrometer-scale structures. SAXS relies on the difference in electron density between different components. It is difficult for SAXS to distinguish the microstructure of components with similar electron densities, such as some organics and polymers. In addition, when studying composite electrolytes, the presence of different phases increases the complexity of data interpretation, and the scattering characteristics of each phase may overlap with each other, making it difficult to resolve them individually. Choosing the right model and fitting it correctly is a challenge, especially in multi-component systems.
分析表明 SAXS 在研究聚合物电解质或复合电解质系统中的微结构和相互作用方面具有强大的应用价值。不过，SAXS 适用于研究 1 至 100 nm 范围内的结构，对于极小的原子尺度结构或较大的微米尺度结构，其分辨率会大大降低。SAXS 依靠的是不同成分之间电子密度的差异。SAXS 难以区分电子密度相似的成分（如某些有机物和聚合物）的微观结构。此外，在研究复合电解质时，不同相的存在增加了数据解读的复杂性，而且各相的散射特征可能相互重叠，难以单独解析。选择合适的模型并正确拟合是一项挑战，尤其是在多组分系统中。

5.5 X-Ray Computed Tomography (CT)
5.5 X 射线计算机断层扫描（CT）

CT technology provides a non-destructive, 3D imaging method to gain insight into the internal microstructure of OICSEs. This is important for understanding the relationship between the microstructure and macroscopic performance of composite electrolytes, optimizing material design, and improving the performance of solid-state batteries [254]. The CT technology can determine the three-dimensional distribution of organic and inorganic phases in a composite electrolyte, measure the porosity of the composite electrolyte, and analyze the morphology, size, and distribution of the pores. Cui et al. [252] presented the self-supported highly porous p-LATP with a thickness of about 260 μm using SEM imaging and further revealed the porous microstructure of p-LATP by CT (Fig. 14c). The uniform pore distribution observed in the 3D reconstructed images of p-LATP and the corresponding 2D sliced images in the x–y and x–z planes demonstrate p-LATP with percolated porous structure has been fabricated successfully. In addition, the 3D images allow the study of pore connectivity and its effect on ionic conduction, as well as the observation of the evolution of defects in the composite electrolyte during use, helping to understand the lifetime and stability of the material. The development of high-power solid-state batteries can be critically supported by CT technology. However, compared to nano-CT, the resolution of CT is low, usually in the micrometer range (about 1–100 µm), which is suitable for larger-scale imaging.
CT 技术提供了一种非破坏性的三维成像方法，用于深入了解 OICSE 的内部微观结构。这对于了解复合电解质的微观结构与宏观性能之间的关系、优化材料设计和提高固态电池的性能非常重要[254]。CT 技术可以确定复合电解质中有机相和无机相的三维分布，测量复合电解质的孔隙率，分析孔隙的形态、大小和分布。Cui 等人[252]利用扫描电镜成像技术展示了厚度约为 260 μm 的自支撑高多孔 p-LATP，并通过 CT 进一步揭示了 p-LATP 的多孔微观结构（图14c）。从 p-LATP 的三维重建图像以及 x-y 和 x-z 平面上相应的二维切片图像中观察到的均匀孔隙分布表明，具有渗流多孔结构的 p-LATP 已被成功制造出来。此外，通过三维图像还可以研究孔隙的连通性及其对离子传导的影响，以及观察复合电解质在使用过程中缺陷的演变，有助于了解材料的寿命和稳定性。CT 技术可为大功率固态电池的开发提供重要支持。然而，与纳米 CT 相比，CT 的分辨率较低，通常在微米范围内（约 1-100 微米），适用于更大规模的成像。

5.6 Atomic Force Microscopy (AFM)
5.6 原子力显微镜 (AFM)

Liu et al. prepared LLZO-PEO composite electrolytes with different weight ratios (0, 50, and 75 wt%) and used in situ conduction atomic force microscopy (c-AFM) to observe the changes in the morphology and mechanical properties of the electrolytes at different temperatures [253]. At 30 °C, most of the PEO in pure PEO (LiClO₄) was in a crystalline state, and when the temperature was increased to 55 °C, most of the PEO changed from crystalline to amorphous, with only a small amount of chain-like crystalline PEO. At 55 °C for the 50 wt% LLZO-PEO sample, the transformation of the chained PEO into an amorphous state can be observed (Fig. 13d). At 30 °C, many LLZO particles can be observed in the AFM topography, and the currents are still concentrated in the amorphous PEO region, with no currents observed inside the LLZO crystal. However, when the temperature is increased to 55 °C (Fig. 14e), currents of the same order of magnitude are observed not only between the LLZO phases but also inside the LLZO crystal. LLZO and PEO can be easily distinguished based on Young's modulus and adhesion. Figure 14f shows the current response in the voltage range of 0–3 V at the grain boundaries, where the current values vary considerably due to the position of the LLZO particles in the electrolyte. This indicates that despite the presence of a large amount of LLZO, PEO remains crystalline at low temperatures and lithium ions cannot migrate rapidly through the LLZO network. However, when a large amount of LLZO is added, it breaks the crystalline chain of PEO and forms a continuous ion migration network in the PEO matrix, and lithium ions can migrate along the LLZO network at high temperatures. However, excess LLZO can accumulate in the matrix and reduce the transport efficiency of lithium ions.
Liu等人制备了不同重量比（0、50和75 wt%）的LLZO-PEO复合电解质，并利用原位传导原子力显微镜（c-AFM）观察了电解质在不同温度下的形貌和力学性能变化[253]。30 °C 时，纯 PEO（LiClO₄）中的 PEO 大部分处于结晶状态，当温度升高到 55 °C 时，大部分 PEO 从结晶变为无定形，只有少量链状结晶 PEO。对于 50 wt% 的 LLZO-PEO 样品，在 55 °C 时可以观察到链状 PEO 转变为无定形状态（图 13d）。在 30 °C 时，可以在原子力显微镜形貌图中观察到许多 LLZO 颗粒，电流仍然集中在无定形 PEO 区域，在 LLZO 晶体内部没有观察到电流。然而，当温度升高到 55 °C（图 14e）时，不仅在 LLZO 相之间，而且在 LLZO 晶体内部都观察到了相同数量级的电流。根据杨氏模量和附着力，很容易区分 LLZO 和 PEO。图14f 显示了晶界处 0-3 V 电压范围内的电流响应，由于 LLZO 颗粒在电解质中的位置不同，电流值也有很大差异。这表明，尽管存在大量 LLZO，但 PEO 在低温下仍保持结晶状态，锂离子无法通过 LLZO 网络快速迁移。 然而，当加入大量 LLZO 时，它会破坏 PEO 的结晶链，并在 PEO 基体中形成连续的离子迁移网络，锂离子可在高温下沿着 LLZO 网络迁移。但是，过量的 LLZO 会在基体中积聚，降低锂离子的迁移效率。

AFM can provide sub-nanometer spatial resolution and, in addition to imaging, can measure mechanical properties of materials (e.g., hardness, Young's modulus). Sample preparation requirements are low, no special treatment of the sample is required, and in-situ observation can be performed directly in different environments (e.g., vacuum, liquid, gas) and under different conditions (e.g., temperature, humidity changes) to monitor changes in the sample in real-time. However, AFM scanning speed is relatively slow, especially in high-resolution mode, and it can take several hours to image a large sample area. Observations can only be made on the surface, with limited ability to examine samples with large thicknesses or internal structures. In addition, the probe wears out after a long time, and the interaction force between the probe and the sample must be precisely controlled to avoid damaging the sample or the probe, as well as to ensure the quality of the image and the accuracy of the measurement.
原子力显微镜可提供亚纳米级的空间分辨率，除成像外，还可测量材料的机械特性（如硬度、杨氏模量）。样品制备要求低，无需对样品进行特殊处理，可在不同环境（如真空、液体、气体）和不同条件（如温度、湿度变化）下直接进行原位观测，实时监测样品的变化。然而，原子力显微镜的扫描速度相对较慢，尤其是在高分辨率模式下，对大面积样品成像可能需要几个小时。只能对样品表面进行观察，对厚度较大的样品或内部结构的检测能力有限。此外，探针在长时间使用后会磨损，必须精确控制探针与样品之间的相互作用力，以避免损坏样品或探针，并确保图像质量和测量精度。

Several commonly utilized techniques are employed to characterize the physicochemical properties of OICSEs. These include X-ray diffraction (XRD) and neutron scattering (NDP) for analyzing crystal structure and phase properties and X-ray photoelectron spectroscopy (XPS) for investigating surface chemical states and elemental distribution, thermal analysis techniques (DSC and TGA) are employed to explore the thermal properties and stability of the electrolyte. Electrochemical impedance spectroscopy (EIS) measures the conductivity and interface properties of the electrolyte, while Raman spectroscopy and infrared spectroscopy are utilized to analyze the molecular vibrational modes of the materials. Integrating these diverse characterization techniques facilitates a comprehensive and detailed understanding of the performance and structure of OICSEs.
有几种常用技术可用于表征 OICSE 的物理化学特性。这些技术包括用于分析晶体结构和相性质的 X 射线衍射 (XRD) 和中子散射 (NDP)，用于研究表面化学状态和元素分布的 X 射线光电子能谱 (XPS)，以及用于探索电解质热性质和稳定性的热分析技术（DSC 和 TGA）。电化学阻抗光谱（EIS）测量电解质的电导率和界面特性，而拉曼光谱和红外光谱则用于分析材料的分子振动模式。整合这些不同的表征技术有助于全面、详细地了解 OICSE 的性能和结构。

6 Summary and Perspective
6 总结与展望

ASSLBs are widely acknowledged as the most promising next-generation energy storage systems owing to their intrinsic safety features and remarkable energy density. This review highlights the development of OICSEs, which are pivotal in SE advancements due to their integration of various electrolytic components. We critically analyze the essential parameters for assessing OICSE performance, including ionic conductivity, Li⁺ transference number, mechanical properties, electrochemical stability, electronic conductivity, and thermal stability. We explore the impact of ceramic fillers on ionic conductivity, considering factors like particle size, content, shape, and dimension. The review also investigates Li⁺ transport mechanisms and the role of different inorganic fillers, both inert (0D particles, 1D nanowires, 2D nanosheets, 3D frameworks) and active (sulfide, garnet, NASICON, and perovskite types) in enhancing OICSE performance. Finally, the importance of advanced characterization techniques for OICSEs is emphasized, as they provide a more comprehensive understanding of the chemical composition, microstructure, and interfacial properties. Despite significant advancements in the research of OICSEs, the technological maturity of ASSLBs utilizing these electrolytes remains insufficient for practical application and commercialization. Therefore, considering the challenges presented by OICSEs in ASSLBs, this review identifies and proposes potential avenues for future research and development.
ASSLB 因其固有的安全特性和显著的能量密度，被公认为最有前途的下一代储能系统。本综述重点介绍 OICSE 的发展情况，由于 OICSE 集成了各种电解元件，因此在 SE 的发展中具有举足轻重的地位。我们认真分析了评估 OICSE 性能的基本参数，包括离子电导率、锂⁺ 转移数、机械性能、电化学稳定性、电子电导率和热稳定性。考虑到粒度、含量、形状和尺寸等因素，我们探讨了陶瓷填料对离子传导性的影响。综述还研究了锂⁺ 传输机制以及不同无机填料（惰性（0D 颗粒、1D 纳米线、2D 纳米片、3D 框架）和活性（硫化物、石榴石、NASICON 和包晶类型））在提高 OICSE 性能方面的作用。最后，还强调了先进表征技术对 OICSE 的重要性，因为这些技术可以让人们更全面地了解 OICSE 的化学成分、微观结构和界面特性。尽管 OICSE 的研究取得了重大进展，但使用这些电解质的 ASSLB 的技术成熟度仍不足以满足实际应用和商业化的需要。因此，考虑到 OICSE 在 ASSLB 中提出的挑战，本综述确定并提出了未来研究和开发的潜在途径。

Despite the improvement in ionic conductivity in previous OICSEs, some significant challenges remain. Presently, the ionic conductivity of most OICSEs lingers in the range of 10⁻⁴ to 10⁻⁵ S cm⁻¹, remaining inferior to that of liquid electrolytes (~ 10⁻² S cm⁻¹). Future strategies to augment ionic conductivity could be directed toward several critical areas of development. (1) Combining different scales of fillers and electrolytes, designing multi-stage pore structure (e.g., 3D LLTO/LATP/LLZO), optimizing ion transport channels from micro to macro level, thereby enhancing overall conductivity. (2) Controlling and adjusting thin film thickness can reduce ion transport distances (Commonly used technologies, including electrostatic spinning, osmotic hot pressing, and combination electrospinning/electrospray technology). Meanwhile, ensuring sufficient mechanical strength and flexibility is crucial to prevent lithium dendrite growth. (3) Introducing of materials rich in surface functional groups (e.g., MXene-Ti₃C₂ and BN with functional groups such as –OH, –O, –NH₂, and –F.), as well as surface modification (e.g., PDA or DMSO modification of LLZTO nanoparticles), etc., to improve the homogeneity of the filler dispersion. (4) Exploring new materials with high Li⁺ transference numbers, including polymers with elevated ion mobility, conductive polymers, and inorganic electrolytes. (5) Employing intelligent design and simulation, leveraging computational simulation, machine learning, and other advanced technologies to design OICSEs.
尽管以前的 OICSE 在离子传导性方面有所改进，但仍然存在一些重大挑战。目前，大多数 OICSE 的离子电导率停留在 10^-4 到 10^-5 S cm^-1 之间、仍低于液态电解质（~ 10^-2 S cm^-1 ）。增强离子传导性的未来战略可以朝着以下几个关键领域发展。(1) 结合不同尺度的填料和电解质，设计多级孔隙结构（如三维 LLTO/LATP/LLZO），从微观到宏观优化离子传输通道，从而提高整体电导率。(2) 控制和调整薄膜厚度可减少离子传输距离（常用技术包括静电纺丝、渗透热压和电纺/电喷组合技术）。同时，确保足够的机械强度和柔韧性是防止锂枝晶生长的关键。(3) 引入富含表面官能团的材料（如 MXene-Ti₃C₂ 和带有 -OH、-O、-NH₂ 和 -F 等官能团的 BN），并进行表面改性（如 PDA 或 DMSO 改性）、LLZTO 纳米粒子的 PDA 或 DMSO 改性）等，以提高填料分散的均匀性。(4) 探索具有高锂⁺ 透射率的新材料，包括离子迁移率高的聚合物、导电聚合物和无机电解质。(5) 采用智能设计和模拟，利用计算模拟、机器学习和其他先进技术设计 OICSE。

Due to multiple complex Li⁺ transport mechanisms, the precise mode of Li-ion transport within these systems remains unclear. Nonetheless, understanding the interactions is crucial for advancing ionic conductivity. Advanced characterization techniques such as solid-state NMR and in-situ characterization methods can be employed to observe variations in ion migration capacity and concentration within OICSEs under different conditions. Moreover, integrating computational approaches, including molecular dynamics simulations and density functional theory, facilitates a thorough investigation of ion transport mechanisms at multiple scales. These simulations are instrumental in predicting ion diffusion pathways and elucidating the impact of interface interactions. Furthermore, tailoring interfaces, namely designing specific interfaces between polymer components and fillers, enables precise control over ion transport channels. Moreover, researchers can harness synergistic effects to enhance ionic conductivity by leveraging the various ion transport mechanisms in different components of OICSEs.
由于存在多种复杂的锂⁺ 传输机制，这些系统中锂离子传输的确切模式仍不清楚。然而，了解这些相互作用对于提高离子导电性至关重要。固态核磁共振和原位表征方法等先进的表征技术可用于观察不同条件下 OICSE 内离子迁移能力和浓度的变化。此外，整合计算方法（包括分子动力学模拟和密度泛函理论）有助于深入研究多种尺度的离子传输机制。这些模拟有助于预测离子扩散路径和阐明界面相互作用的影响。此外，定制界面，即设计聚合物成分和填料之间的特定界面，可实现对离子传输通道的精确控制。此外，研究人员还可以利用 OICSE 不同成分中的各种离子传输机制，发挥协同效应，增强离子传导性。

The interface in OICSEs primarily encompasses two aspects: between the polymer and fillers and between the OICSEs and electrodes. Optimizing interface stability is crucial for improving the performance and extending the cycle life of ASSLBs. The disparate chemical properties and interactions between polymers and inorganic fillers often lead to interfacial compatibility issues. To address this issue, surface modification techniques that introduce appropriate functional groups have been implemented to enhance compatibility with the polymer matrix, consequently promoting the uniform dispersion of nanoparticles. Additionally, incorporating small molecule plasticizers, such as SN, has proven effective in enhancing interfacial compatibility. The contact between OICSEs and electrodes can lead to electrochemical reactions, triggering interfacial degradation and instability. In situ polymerization can create a uniform, continuous, and dense interfacial layer on the electrode surface, effectively reducing interfacial resistance, which is one of the critical development directions. In the field of ASSLBs, a pivotal objective is the development of OICSEs that exhibit resistance to high voltages, improve compatibility with high-voltage cathodes, and effectively protect the interface from electrochemical reactions and degradation. Furthermore, employing special coating technologies (e.g., OICSEs reacting with Li metal to produce in situ protective layers such as LiF, or introducing polymer buffer layers such as PVDF and PEO) can improve the intimate contact between OICSE and electrodes or enhance interaction through the innovative design of electrode structures. Through the optimization of the OICSEs interface, a more efficient and stable energy storage device can be achieved, thereby promoting the development and practical application of battery technology.
OICSE 的界面主要包括两个方面：聚合物与填料之间以及 OICSE 与电极之间。优化界面稳定性对于提高 ASSLB 的性能和延长其循环寿命至关重要。聚合物和无机填料之间不同的化学性质和相互作用往往会导致界面兼容性问题。为解决这一问题，我们采用了引入适当官能团的表面改性技术，以增强与聚合物基体的相容性，从而促进纳米粒子的均匀分散。此外，事实证明，加入 SN 等小分子增塑剂可有效提高界面相容性。OICSE 与电极的接触会导致电化学反应，引发界面降解和不稳定。原位聚合可在电极表面形成均匀、连续、致密的界面层，有效降低界面电阻，这也是关键的发展方向之一。在 ASSLB 领域，一个关键目标是开发出具有耐高压性能的 OICSE，提高与高压阴极的兼容性，并有效保护界面免受电化学反应和降解的影响。此外，采用特殊涂层技术（例如 OICSE 与锂金属反应生成原位保护层（如 LiF），或引入聚合物缓冲层（如 PVDF 和 PEO））可改善 OICSE 与电极之间的亲密接触，或通过电极结构的创新设计增强相互作用。 通过优化 OICSE 接口，可以实现更高效、更稳定的储能装置，从而促进电池技术的发展和实际应用。

More detailed and accurate information on OICSEs can be obtained through advanced characterization techniques. This offers valuable insights into the internal interfacial structure, composition, properties, and behavior of these materials. Nonetheless, these techniques face significant challenges, including balancing high resolution with rapid data acquisition. Increasing data acquisition speed may reduce resolution while enhancing resolution can slow down the process. Additionally, these techniques often generate large volumes of data, complicating the extraction of valuable insights and precise analysis. Integrating experimental results with theoretical models is essential for accurately characterizing samples. Another challenge is that numerous advanced techniques demand specialized sample handling or preparation, encompassing procedures such as cutting, grinding, coating, etc. Therefore, future directions include integrating different characterization techniques to provide more comprehensive information. Further development of techniques for in-situ observation and atomic-level resolution will contribute to a deeper understanding of material behavior and changes under different conditions. Simultaneously, refining non-invasive characterization techniques, especially for precious samples, becomes important to prevent sample damage.
通过先进的表征技术，可以获得有关 OICSE 的更详细、更准确的信息。这为深入了解这些材料的内部界面结构、成分、特性和行为提供了宝贵的资料。然而，这些技术面临着巨大的挑战，包括在高分辨率与快速数据采集之间取得平衡。提高数据采集速度可能会降低分辨率，而提高分辨率又会减慢采集速度。此外，这些技术通常会产生大量数据，从而使宝贵见解的提取和精确分析变得更加复杂。将实验结果与理论模型相结合对于准确表征样品至关重要。另一个挑战是，许多先进技术需要专门的样品处理或制备，包括切割、研磨、涂层等程序。因此，未来的发展方向包括整合不同的表征技术，以提供更全面的信息。原位观测和原子级分辨率技术的进一步发展将有助于更深入地了解材料在不同条件下的行为和变化。同时，完善非侵入式表征技术，尤其是针对贵重样品的表征技术，对于防止样品损坏也非常重要。

Roll-to-roll processing for solid-state batteries is a continuous, high-productivity manufacturing technology suitable for large-scale production, which is similar to the large-scale continuous roll-to-roll process used to manufacture conventional lithium-ion batteries, but the process needs to be adapted to handle solid-state materials and ensure compatibility with high-voltage cathodes and lithium metal anodes. Roll-to-roll processing significantly reduces manufacturing costs by reducing material waste and improving production efficiency and is suitable for manufacturing large-area and flexible electronic devices. The Central Research Institute of Electric Power of Japan has prepared a two-layer polymer battery cell using roll-to-roll technology with an output voltage of 12 V. The positive electrode is LiNi_1/3Mn_1/3Co_1/3O₂ with a potential of more than 4 V, the negative electrode is graphite, and the solid electrolyte is a polyether material. The 3D printing technology, with a high degree of design freedom and rapid prototyping, is suitable for producing personalized and complex structures, realizing novel structures that are unattainable by traditional methods, thus enhancing ionic conductivity and mechanical stability. Despite the advantages of 3D printing technology in customizing battery components, printing accuracy still needs to be improved and is currently relatively expensive. However, the cost issue is expected to be alleviated as the technology continues to advance. Thus, both roll-to-roll machining and 3D printing technologies offer promising paths to scalable and cost-effective manufacturing of solid-state batteries.
固态电池的卷对卷加工是一种适用于大规模生产的连续、高生产率制造技术，它与用于制造传统锂离子电池的大规模连续卷对卷工艺类似，但需要对工艺进行调整，以处理固态材料，并确保与高压正极和锂金属负极的兼容性。卷对卷加工可减少材料浪费，提高生产效率，从而大大降低制造成本，适用于制造大面积和柔性电子设备。日本中央电力研究所利用卷对卷技术制备了一种输出电压为 12 V 的双层聚合物电池。正极是镍镉锂_1/3Mn_1/3Co_1/3O₂ ，电位超过 4 V，负极是石墨，固体电解质是聚醚材料。三维打印技术具有设计自由度高和快速成型的特点，适合制作个性化的复杂结构，实现传统方法无法实现的新颖结构，从而提高离子导电性和机械稳定性。尽管 3D 打印技术在定制电池组件方面具有优势，但打印精度仍有待提高，而且目前成本相对较高。不过，随着技术的不断进步，成本问题有望得到缓解。因此，辊对辊加工和三维打印技术都为实现固态电池的规模化和高成本效益制造提供了广阔的前景。