Electrospinning-derived ${ZnCo}_{2} O_{4} @$ carbon nanofiber composite for high-performance lithium ion storage
用于高性能锂离子存储的电纺丝衍生 ${ZnCo}_{2} O_{4} @$ 碳纳米纤维复合材料

Hong Tang $^{a, b}$ , Mengjin Jiang $^{c}$ , Wenhao Bai $^{a, b}$ , Ce Cui $^{a, b}$ , Hongyan Xiao $^{a, b}$ , Erhui Ren $^{a, b}$ ,
唐红 $^{a, b}$ 、蒋梦瑾 $^{c}$ 、白文豪 $^{a, b}$ 、崔策 $^{a, b}$ 、肖红艳 $^{a, b}$ 、任尔辉 $^{a, b}$ 、Mi Zhou $^{a}$ , Jinwei Zhang $^{a}$ , Cheng Cheng $^{d}$ , Ronghui Guo $^{a, b,^{*}}$
Mi Zhou $^{a}$ 、Jinwei Zhang $^{a}$ 、Cheng Cheng $^{d}$ 、Ronghui Guo $^{a, b,^{*}}$ $^{a}$ College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, China
$^{a}$ 四川大学生物质科学与工程学院，中国成都，610065 $^{b}$ Yibin Industrial Technology Research Institute of Sichuan University, Yibin, Sichuan, China
$^{b}$ 四川大学宜宾产业技术研究院，中国四川宜宾 $^{c}$ College of Polymer Science & Engineering and State Key Lab Polymer Material & Engineering, Sichuan University, Chengdu, 610065, China
$^{c}$ 四川大学高分子科学与工程学院、高分子材料与工程国家重点实验室，成都，610065 $^{d}$ School of Chemical and Process Engineering, University of Leeds, Leeds, United Kingdom
$^{d}$ 利兹大学化学与工艺工程学院，英国，利兹

A R TICLE IN F O
文章

Handling Editor: Dr P. Vincenzini
责任编辑：P. Vincenzini 博士P. Vincenzini 博士

Keywords: 关键词：

Electrospinning 电纺丝

{ZnCo}_{2} O_{4}

Carbon nanofiber 纳米碳纤维
Long-cycle performance 长周期性能
Lithium ion storage 锂离子存储器

Abstract 摘要

A B S T R A C T The degradation of the cobalt-zinc oxide structure and its poor conductivity during the charge and discharge limit their further applications for lithium ion storage. Herein, ${ZnCo}_{2} O_{4} @$ carbon nanofiber composite with nanofibrous structure is obtained by electrospinning, annealing in argon and low-temperature oxidation to effectively overcome the above issue. The active sites of ${ZnCo}_{2} O_{4}$ are evenly dispersed inside the carbon nanofibers, which can effectively avoid its aggregation and improve electrical conductivity. Additionally, the stable nanofibrous structure can maintain structural stability. The composite exhibits superior lithium ion storage capacity when being served as anode electrode. The ${ZnCo}_{2} O_{4} @$ carbon nanofiber electrode possesses a high capacity of 1071
A B S T R A C T 氧化钴锌结构的降解及其在充放电过程中的不良导电性限制了其在锂离子存储领域的进一步应用。在此，通过电纺丝、氩气退火和低温氧化得到了具有纳米纤维结构的 ${ZnCo}_{2} O_{4} @$ 碳纳米纤维复合材料，有效地克服了上述问题。 ${ZnCo}_{2} O_{4}$ 的活性位点均匀地分散在碳纳米纤维内部，可有效避免其聚集，提高导电性。此外，稳定的纳米纤维结构还能保持结构的稳定性。该复合材料在用作阳极电极时表现出卓越的锂离子存储能力。 ${ZnCo}_{2} O_{4} @$ 碳纳米纤维电极的容量高达 1071

maintain $714 mA h g^{- 1}$ after 250 cycles when current density is adjusted to $0.2 A g^{- 1}$ again. Additionally, the electrode has an outstanding long-cycle performance, which remains a capacity of $447.165 mA h^{- 1}$ at $0.5 A g^{- 1}$ after 500 cycles and $421.477 mA h g^{- 1}$ at $1 A g^{- 1}$ after 518 cycles. This result demonstrates that ${ZnCo}_{2} O_{4} @$ carbon nanofiber composite has potential application prospects in the fields of advanced energy storage.
当电流密度再次调整到 $0.2 A g^{- 1}$ 时，250 次循环后仍能保持 $714 mA h g^{- 1}$ 的容量。此外，该电极还具有出色的长循环性能，在 500 次循环后， $0.5 A g^{- 1}$ 的容量仍为 $447.165 mA h^{- 1}$ ，在 518 次循环后， $1 A g^{- 1}$ 的容量仍为 $421.477 mA h g^{- 1}$ 。这一结果表明， ${ZnCo}_{2} O_{4} @$ 碳纳米纤维复合材料在先进储能领域具有潜在的应用前景。

1. Introduction 1.导言

Lithium-ion batteries, as the most important rechargeable batteries in modern commercial batteries, have been widely used in energy storage systems and portable electronic devices [1]. However, lithium-ion batteries urgently need to improve energy density, long life as well as low cost when lithium-ion batteries are further applied in the fields of power store systems, electric cars and aerospace [2-4]. The endurance capacity of lithium-ion batteries usually depends on the capacity of anode material due to the capacity limitation of cathode material [5], nevertheless, the conventional graphite anodes is far from being able to satisfy the ever-increasing energy demand due to its low capacity [6]. Therefore, it is becoming more and more urgent to explore lithium ion storage materials with high capacity.
锂离子电池作为现代商用电池中最重要的可充电电池，已被广泛应用于储能系统和便携式电子设备中[1]。然而，当锂离子电池进一步应用于储能系统、电动汽车和航空航天领域时，锂离子电池亟需提高能量密度、延长使用寿命并降低成本[2-4]。由于正极材料的容量限制，锂离子电池的续航能力通常取决于负极材料的容量[5]，然而传统的石墨负极由于容量低，远远不能满足日益增长的能源需求[6]。因此，探索高容量锂离子存储材料变得越来越迫切。

Among the alternatives of various anode electrode materials, metal oxides own high theoretical capacity as result of the conversion reaction and the alloying reaction of partial metal oxides during lithium ion storage, which make it received a lot of attention [7,8]. As a typical transition metal oxide, the bimetallic oxide

{ZnCo}_{2} O_{4}

has a promising application prospect when being used as a new generation of lithium ion storage material. However, when

{ZnCo}_{2} O_{4}

reacts with lithium ions, the

{ZnCo}_{2} O_{4}

undergoes a conversion reaction to produce metal Co and Zn , and then the Zn alloying with

{Li}^{+}

to form

{Li}_{2} Zn

alloy, which always causes large volume fluctuations of the structure and the repeated insertion and extract of lithium ions will lead to structure of material become unstable and even cause collapse [9], thereby cause severe decline in capacity and a lower service life. In addition, the

{ZnCo}_{2} O_{4}

has poor electrical conductivity and inferior electron mobility, which makes it difficult for some active sites to intercalate and deintercalate with lithium ions, resulting in poor rate performance and reaction kinetics.
在各种正极电极材料中，金属氧化物因其在锂离子存储过程中的转化反应和部分金属氧化物的合金化反应而具有较高的理论容量，因而受到广泛关注[7,8]。作为一种典型的过渡金属氧化物，双金属氧化物

{ZnCo}_{2} O_{4}

作为新一代锂离子存储材料具有广阔的应用前景。然而，当

{ZnCo}_{2} O_{4}

与锂离子反应时，

{ZnCo}_{2} O_{4}

会发生转化反应生成金属Co和Zn，然后Zn与

{Li}^{+}

合金化形成

{Li}_{2} Zn

合金，这总会引起结构体积的大幅波动，锂离子的反复插入和提取会导致材料结构变得不稳定，甚至造成坍塌[9]，从而导致容量严重下降，使用寿命降低。此外，

{ZnCo}_{2} O_{4}

导电性差，电子迁移率低，一些活性位点难以与锂离子发生插层和脱插层反应，导致速率性能和反应动力学性能不佳。

In order to solve this problem, many efforts have used to regulate the microstructure of

{ZnCo}_{2} O_{4}

with stable structure, thereby avoiding structural collapse and aggregation of active sites in the process of charging and discharging, which in turn enables more active sites reacts with lithium ions and reduces the capacity attenuation caused by the degradation of unstable structure [10,11].

{ZnCo}_{2} O_{4}

-based composite
为了解决这一问题，许多人致力于用稳定的结构来调节

{ZnCo}_{2} O_{4}

的微观结构，从而避免在充放电过程中出现结构坍塌和活性位点聚集，进而使更多的活性位点与锂离子发生反应，减少因结构不稳定而导致的容量衰减 [10,11]。基于

{ZnCo}_{2} O_{4}

的复合材料

with various structures have been regulated toward improve lithium ion storage capacity such as PAN (Polyacrylonitrile) -based carbon fiber/

{ZnCo}_{2} O_{4}

[12],

{ZnCo}_{2} O_{4}

hierarchical nanocubes [13],

{ZnCo}_{2} O_{4}

Nanowire [14],

{ZnCo}_{2} O_{4} / ZnO / C

microcubes [15], nano-

{ZnCo}_{2} O_{4}

/porous rGO [16], yolk-shell structured

{ZnCo}_{2} O_{4}

spheres [17] and hierarchical porous

{ZnCo}_{2} O_{4} @ NiO /

nickel foam [18]. The stability of

{ZnCo}_{2} O_{4}

and the lithium ion storage performance were improved. Nevertheless, this synthesis processes are often complicated, poorly controllable and cannot maintain consistency well. It is a very valuable question to prepare composite with porosity, good conductivity and stable structure through simple preparation processes. Compared with this complex structure, the preparation of composite with nanofiber structure by electrospinning is simple and easy controllable, which is conducive to mass production and has greater application prospects [19]. The active sites are uniformly distributed in the nanofibers, which is beneficial to participate in the electrochemical reaction during charge and discharge.
为提高锂离子存储容量，对各种结构的碳纤维进行了调节，如基于 PAN（聚丙烯腈）的碳纤维/

{ZnCo}_{2} O_{4}

[12]、

{ZnCo}_{2} O_{4}

分层纳米立方体[13]、

{ZnCo}_{2} O_{4}

纳米线 [14]、

{ZnCo}_{2} O_{4} / ZnO / C

微立方体 [15]、纳米

{ZnCo}_{2} O_{4}

/多孔 rGO [16]、卵黄壳结构

{ZnCo}_{2} O_{4}

球 [17]和分层多孔

{ZnCo}_{2} O_{4} @ NiO /

泡沫镍 [18]。

{ZnCo}_{2} O_{4}

的稳定性和锂离子存储性能都得到了提高。然而，这种合成工艺往往比较复杂，可控性差，不能很好地保持一致性。如何通过简单的制备工艺制备出具有多孔性、良好导电性和稳定结构的复合材料是一个非常有价值的问题。与这种复杂的结构相比，电纺丝法制备纳米纤维结构的复合材料工艺简单，易于控制，有利于大规模生产，具有更大的应用前景[19]。活性位点均匀分布在纳米纤维中，有利于在充放电过程中参与电化学反应。

In this work, the transition metal oxide composite with fibrous structure were rationally designed by using electrospinning. The

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

nanofibers were prepared by electrospinning, and then carbonized at high temperature to form Zn@Co@carbon nanofiber composite, so that it can effectively maintain the fibrous structure. Afterwards, the composite was oxidized in the air to obtain

{ZnCo}_{2} O_{4} @

carbon nanofiber composite, which is beneficial to avoid the degradation of the fiber structure caused by the direct oxidation of

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

nanofibers in air. In the composite, the presence of a large number of heteroatoms N come from PAN helps to improving conductivity and affinity of lithium ion. In addition, the large specific surface area of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite allows it to give many active sites for the insertion/extraction of lithium ions. Benefited from these advantages, the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode exhibits a high capacity of

1053.88 mA h g^{- 1}

when the current density is

0.1 A g^{- 1}

. In addition, the electrode possesses outstanding rate perfor-
本研究利用电纺丝技术合理设计了具有纤维结构的过渡金属氧化物复合材料。通过电纺丝制备出

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

纳米纤维，然后在高温下碳化形成Zn@Co@碳纳米纤维复合材料，使其能有效保持纤维状结构。之后，将复合材料在空气中氧化，得到

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料，有利于避免

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

纳米纤维在空气中直接氧化造成的纤维结构退化。复合材料中存在大量来自 PAN 的杂原子 N，有助于提高锂离子的导电性和亲和性。此外，

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的大比表面积使其能够为锂离子的插入/萃取提供许多活性位点。得益于这些优点，当电流密度为

0.1 A g^{- 1}

时，

{ZnCo}_{2} O_{4} @

碳纳米纤维电极显示出

1053.88 mA h g^{- 1}

的高容量。此外，该电极还具有出色的速率性能。

946.998 mA h g^{- 1}

when current density returns to

0.1 A g^{- 1}

again. Moreover, the electrode has excellent recyclable performance, which delivers

635.175 mA h g^{- 1}

0.5 {Ag}^{- 1}

over 135 cycles and maintains

424.615 mA h g^{- 1}

1 {Ag}^{- 1}

over 300 cycles.

946.998 mA h g^{- 1}

当电流密度再次恢复到

0.1 A g^{- 1}

时。此外，该电极还具有出色的可回收性能，可在 135 次循环中以

0.5 {Ag}^{- 1}

提供

635.175 mA h g^{- 1}

，并在 300 次循环中以

1 {Ag}^{- 1}

保持

424.615 mA h g^{- 1}

。

2. Experimentals 2.试验品

2.1. Preparation of metal ion ${Zn}^{2 +}$ @Co $^{2 +}$ @PAN@nanofibers
2.1.制备金属离子 ${Zn}^{2 +}$ @Co $^{2 +}$ @PAN@ 纳米纤维

219 mg Co {({CH}_{3} COO)}_{2} \cdot 4 H_{2} O, 498 mg Zn {({CH}_{3} COO)}_{2} \cdot 2 H_{2} O

and 1.0 g polyacrylonitrile (PAN) were dissolved in

10 mL N, N - 2

methyl formamide (DMF) under the condition of magnetic stirring at room temperature to become a uniformly dispersed solution for electrospinning. The solution was then transferred to a syringe and fix it on syringe pump. A positive voltage of 20 kV was used for spinneret, and delivery rate of

0.5 mL / \min

was controlled to eject the spinning solution from the spinneret. Additionally, the distance between a uniformly rotating round drum wrapped with aluminum foil and spinneret was 15 cm . The metal ion

{Zn}^{2 +} @ {Co}^{2 +} @ P A N @

nanofiber film was collected on aluminum foil after the electrospinning was completed.

219 mg Co {({CH}_{3} COO)}_{2} \cdot 4 H_{2} O, 498 mg Zn {({CH}_{3} COO)}_{2} \cdot 2 H_{2} O

和 1.0 克聚丙烯腈（PAN）在室温磁力搅拌条件下溶解于

10 mL N, N - 2

甲基甲酰胺（DMF）中，成为均匀分散的溶液，用于电纺丝。然后将溶液转移到注射器中，并固定在注射泵上。喷丝板使用 20 kV 的正电压，控制

0.5 mL / \min

的输送速率，将纺丝溶液从喷丝板喷出。此外，用铝箔包裹的匀速转动圆鼓与喷丝板之间的距离为 15 厘米。电纺丝完成后，在铝箔上收集金属离子

{Zn}^{2 +} @ {Co}^{2 +} @ P A N @

纳米纤维膜。

2.2. Synthesis of ${ZnCo}_{2} O_{4}$ @carbon nanofiber composite
2.2. ${ZnCo}_{2} O_{4}$ @碳纳米纤维复合材料的合成

The

{Zn}^{2 +}

@Co

^{2 +}

@PAN nanofibers was immersed in a tube furnace and heated up to

600^{\circ} C

in argon atmosphere, then maintain at

600^{\circ} C

for 4 h and annealing to obtain Zn@Co@carbon nanofiber composite. Afterwards, the Zn@Co@carbon nanofiber composite was transferred to muffle furnace and heated to

300^{\circ} C

, and oxidized at

300^{\circ} C

for 3 h to obtain

{ZnCo}_{2} O_{4} @

carbon nanofiber composite.
将

{Zn}^{2 +}

@Co

^{2 +}

@PAN 纳米纤维浸入管式炉中，在氩气气氛下加热至

600^{\circ} C

，然后在

600^{\circ} C

下保持 4 小时并退火，得到 Zn@Co@carbon 纳米纤维复合材料。然后，将 Zn@Co@carbon 纳米纤维复合材料转移到马弗炉中，加热到

300^{\circ} C

，在

300^{\circ} C

下氧化 3 小时，得到

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料。

2.3. Characterization 2.3.特征描述

The SEM (JEOL, JSM-5900LV) and TEM (FEI Talos-S) was used to obverse the morphology of the sample. The D/Max-III X-ray spectrometer (PANalytical/Philips X’Pert Pro) was performed to test XRD patterns. The electron energy disperse spectroscopy (ThermofIsher ScientifIc Escalab 250Xi, USA) was conducted to evaluate XPS. nitrogen sorption-desorption isotherms was performed by adsorption apparatus (Gemini VII 2390).
扫描电子显微镜（JEOL，JSM-5900LV）和电子显微镜（FEI Talos-S）用于观察样品的形态。D/Max-III X 射线光谱仪（PANalytical/Philips X'Pert Pro）用于测试 XRD 图样。用吸附仪（Gemini VII 2390）进行氮吸附-解吸等温线分析。

2.4. Electrochemical measurement
2.4.电化学测量

The synthesized

{ZnCo}_{2} O_{4} @

carbon nanofiber composite was assembled into standard CR2032-type coin cells for electrochemical test and

{ZnCo}_{2} O_{4} @

carbon nanofiber electrodes were prepared by a slurry coating. In detail,

{ZnCo}_{2} O_{4} @

carbon nanofiber composite, acetylene black and sodium carboxymethylcellulose (weight ratio is

8 : 1 : 1

) dispersed in deionized water to obtain homogeneous ink-like slurry and coated on Cu foil, afterwards, kept it in vacuum oven at

60^{\circ} C

. The electrode was obtained by cut it into wafer (the diameter is 12 mm ). A

200 μ m

thick scraper is used for coating electrode and the load of active material on the electrode paste coating is about

2.0 mg {cm}^{2}

. CR2032 button battery is assembled in a vacuum glove box filled with argon, Li foil and polypropylene membrane is used as counter electrode and battery separator, the electrolyte is dissolved in

1.0 M {LiPF}_{6}

in ethylene carbonate/dimethyl carbonate solution with a volume ratio of 1:1. The battery test system was employed to test galvanostatic charge and discharge performance. The CHI660E electrochemical workstation was performed to test CV curve and EIS spectrum (see Fig. 1).
将合成的

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料组装到标准 CR2032 型纽扣电池中进行电化学测试，并通过浆料涂层制备

{ZnCo}_{2} O_{4} @

碳纳米纤维电极。具体来说，将纳米碳纤维复合材料、乙炔黑和羧甲基纤维素钠（重量比为

8 : 1 : 1

）分散在去离子水中，得到均匀的油墨状浆料，涂覆在铜箔上，然后将其置于

60^{\circ} C

真空烘箱中保存。将电极切割成晶片（直径为 12 毫米）。使用

200 μ m

厚的刮刀涂覆电极，电极膏涂层上的活性物质含量约为

2.0 mg {cm}^{2}

。CR2032 纽扣电池在充有氩气的真空手套箱中组装，锂箔和聚丙烯膜用作对电极和电池隔膜，电解液溶于

1.0 M {LiPF}_{6}

体积比为 1:1 的碳酸乙烯酯/碳酸二甲酯溶液中。电池测试系统用于测试电静态充放电性能。使用 CHI660E 电化学工作站测试 CV 曲线和 EIS 光谱（见图 1）。

3. Results and discussion
3.结果和讨论

The micromorphology of

{Zn}^{2 +} @ {Co}^{2 +}

PAN nanofibers, Zn@Co@carbon nanofiber composite and

{ZnCo}_{2} O_{4}

nanofiber composite were observed using SEM and TEM, as shown in Fig. 2. The

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

nanofibers obtained by electrospinning present a fiber structure with smooth surface, and the fiber diameter distribution is uniform (Fig. 2a). The Zn@Co@carbon nanofiber composite obtained after calcination in argon has no obvious change in the diameter of the fiber, and the surface becomes rough due to the decomposition of PAN (Shortening of the fiber is because the sample was ground into powder before the SEM test), as shown in Fig. 2 b. The final

{ZnCo}_{2} O_{4}

nanofiber composite obtained after low-temperature oxidation in oxygen is shown in Fig. 2c. The diameter of the nanofibers shrinks slightly after oxidation, but the fiber-like structure is still maintained.
利用 SEM 和 TEM 观察了

{Zn}^{2 +} @ {Co}^{2 +}

PAN 纳米纤维、Zn@Co@碳纳米纤维复合材料和

{ZnCo}_{2} O_{4}

纳米纤维复合材料的微观形貌，如图 2 所示。电纺得到的

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

纳米纤维呈纤维结构，表面光滑，纤维直径分布均匀（图 2a）。如图 2 b 所示，在氩气中煅烧后得到的 Zn@Co@carbon 纳米纤维复合材料的纤维直径没有明显变化，表面因 PAN 的分解而变得粗糙（纤维变短是因为样品在 SEM 测试前被研磨成粉末）。氧化后纳米纤维的直径略有收缩，但仍保持纤维状结构。

The TEM image of

Zn @ C o @ c a r b o n

nanofiber composite is shown in Fig. 2d. A nanofiber structure can be clearly observed and the diameter of the nanofiber is about 200 nm . In addition, it can be obvious that there are some nanoclusters inside the nanofibers. It can be found that the nanoparticles are Co nanoclusters after comparing with the corresponding elemental mapping image (Fig. S1), which are distributed inside the nanofibers. In addition, the nanoclusters are surrounded by carbon, zinc and cobalt with amorphous state. The HR-TEM image of Zn@Co@carbon nanofiber composite is shown in the inset of Fig. 2d. The lattice fringes can be clearly observed inside the Co nanoclusters and the corresponding cobalt (111) lattice distance is 0.205 nm [20]. The outside of the Co nanoclusters are amorphous structures, which is attributed to the fact that carbon, zinc and cobalt are uniformly distributed throughout carbon nanofibers. TEM image of the

{ZnCo}_{2} O_{4} @

carbon nanofiber is shown in Fig. 2e. The

Zn @ C o @ c a r b o n

nanofiber composite can still maintain the nanofiber structure after low-temperature oxidation, which is confirmed by SEM image. Black nanoclusters are embedded in the nanofibers, and it has been confirmed to be

{ZnCo}_{2} O_{4}

nanoclusters according to elemental mapping of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite. The lattice morphology of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite has been further studied by HR-TEM, as presented in Fig. 2 f.

{ZnCo}_{2} O_{4} @

carbon nanofiber composite exhibits an amorphous structure except for the good lattice crystallization effect in the nanoclusters, which also explains well that the XRD

Zn @ C o @ c a r b o n

纳米纤维复合材料的 TEM 图像如图 2d 所示。可以清晰地观察到纳米纤维结构，纳米纤维的直径约为 200 nm。此外，还可以明显看到纳米纤维内部存在一些纳米团簇。与相应的元素图谱图像（图 S1）相比，可以发现纳米粒子是 Co 纳米团簇，它们分布在纳米纤维内部。此外，纳米团簇周围还存在非晶态的碳、锌和钴。Zn@Co@carbon 纳米纤维复合材料的 HR-TEM 图像见图 2d。在钴纳米团簇内部可以清晰地观察到晶格条纹，相应的钴（111）晶格间距为 0.205 nm [20]。钴纳米团簇的外部是无定形结构，这是因为碳、锌和钴均匀地分布在整个碳纳米纤维中。

{ZnCo}_{2} O_{4} @

碳纳米纤维的 TEM 图像如图 2e 所示。经扫描电镜图像证实，

Zn @ C o @ c a r b o n

纳米纤维复合材料在低温氧化后仍能保持纳米纤维结构。黑色纳米团簇嵌入纳米纤维中，根据

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的元素图谱，确认其为

{ZnCo}_{2} O_{4}

纳米团簇。通过 HR-TEM 进一步研究了

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的晶格形貌，如图 2 f 所示。

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料除了在纳米团簇中具有良好的晶格结晶效果外，呈现出无定形结构。

Fig. 1. Schematic diagram of preparation of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite.
图 1.

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的制备示意图。

Fig. 2. (a) SEM image of

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

nanofiber; (b) SEM image of

Zn @ C o @ c a r b o n

nanofiber composite; © SEM image of

{ZnCo}_{2} O_{4} @ c a r b o n n a n o f i b e r

图 2：（a）

{Zn}^{2 +} @ {Co}^{2 +} @ P A N

纳米纤维的 SEM 图像；（b）

Zn @ C o @ c a r b o n

纳米纤维复合材料的 SEM 图像；©

{ZnCo}_{2} O_{4} @ c a r b o n n a n o f i b e r

的 SEM 图像

image of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite. (g) Energy dispersive X-ray element mapping images of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite.

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的图像。(g)

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的能量色散 X 射线元素映射图像。
spectrum of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite show only weak diffraction peaks but not strong diffraction peaks of

{ZnCo}_{2} O_{4}

. A clearer

{ZnCo}_{2} O_{4}

lattice diagram is obtained after Fourier (FET) transformation of

{ZnCo}_{2} O_{4}

nanocluster with good crystallinity in the HR-TEM image, as shown in the inset of Fig. 2 f. Compared with the XRD standard card, a lattice spacing of 0.24 nm is assigned to (311) crystal plane spacing of

{ZnCo}_{2} O_{4}

[21]. Besides, a lattice spacing of 0.52 nm is attributed to typical lattice constant c of ZnO [22]. Element mapping test was performed to study composition, as shown in Fig. 2 g. The

Zn, O, N

and C are uniformly dispersed in nanofibers and Co is more distributed in nanoclusters due to the formation of

{ZnCo}_{2} O_{4}

nanoclusters with good crystallinity.

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的光谱仅显示出微弱的衍射峰，而

{ZnCo}_{2} O_{4}

的衍射峰却不强。如图 2 f 的插图所示，经过傅立叶（FET）变换后，

{ZnCo}_{2} O_{4}

纳米团簇的晶格图更加清晰，在 HR-TEM 图像中具有良好的结晶性。与 XRD 标准卡相比，

{ZnCo}_{2} O_{4}

的（311）晶面间距为 0.24 nm [21]。此外，0.52 nm 的晶格间距归因于氧化锌的典型晶格常数 c [22]。如图 2 g 所示，

Zn, O, N

和 C 均匀地分散在纳米纤维中，而 Co 则更多地分布在纳米团簇中，这是因为形成了结晶度良好的

{ZnCo}_{2} O_{4}

纳米团簇。

The composition and crystal plane information of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite is further identify by X-ray diffraction (XRD), as presented in Fig. 3 a. In the XRD spectrum of PAN@carbon nanofibers, it is obvious that there is a strong peak at

{25.8}^{\circ}

, which is derived from the
通过 X 射线衍射 (XRD) 进一步确定了

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的成分和晶面信息，如图 3 a 所示。

Fig. 3. (a) XRD spectra of PAN@carbon nanofiber composite,

Zn @ C o @ c a r b o n

nanofiber composite and

{ZnCo}_{2} O_{4} @

carbon nanofiber composite. The high-resolution XPS spectrum of (b) Co 2 p, © O1s, (d) Zn 2 p and (e) N1s. (f) The nitrogen adsorption-desorption curve and corresponding pore size distribution curve of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite.
图 3：（a）PAN@碳纳米纤维复合材料、

Zn @ C o @ c a r b o n

纳米纤维复合材料和

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的 XRD 光谱。(b) Co 2 p、© O1s、(d) Zn 2 p 和 (e) N1s 的高分辨率 XPS 光谱。(f)

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的氮吸附-解吸曲线和相应的孔径分布曲线。
diffraction peak of amorphous carbon in PAN@carbon nanofibers. A weak diffraction peak appears at the diffraction angle of

{44.2}^{\circ}

in the spectrum of Zn@Co@carbon nanofiber composite, which correspond to the (111) crystal plane of the metal Co (JCPDS NO.15-0806). In the XRD spectrum of

{ZnCo}_{2} O_{4} @

carbon nanofiber composite, a strong diffraction peak at

{36.8}^{\circ}

can be clearly observed for the composite after oxidation in the air. Through comparison of XRD standard cards (JCPDS NO.150806), the peak comes from the strongest diffraction peak of the (311) crystal plane of

{ZnCo}_{2} O_{4}

, which accords with (311) interplanar spacing observed by TEM. In addition, the positions of other characteristic peaks in the XRD pattern do not show strong diffraction peaks, which are caused by that a large number of amorphous structures are uniformly dispersed inside the carbon nanofibers. The result is in accord with the morphology observed in the corresponding TEM images.
PAN@carbon 纳米纤维中无定形碳的衍射峰。在 Zn@Co@carbon 纳米纤维复合材料的 XRD 光谱中，

{44.2}^{\circ}

衍射角处出现了一个较弱的衍射峰，对应于金属 Co 的（111）晶面（JCPDS NO.15-0806）。在

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的 XRD 光谱中，可以清晰地观察到复合材料在空气中氧化后在

{36.8}^{\circ}

处出现了一个较强的衍射峰。通过对比 XRD 标准卡（JCPDS NO.150806），该峰值来自

{ZnCo}_{2} O_{4}

晶面（311）的最强衍射峰，与 TEM 观察到的（311）平面间距一致。此外，X 射线衍射图谱中其他特征峰的位置也没有出现强衍射峰，这是因为碳纳米纤维内部均匀分散着大量无定形结构。这一结果与相应的 TEM 图像中观察到的形态一致。

Element valence state of the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite was studied by X-ray photoelectron spectroscopy. In Fig. S2 a. It can be obvious that

Zn, O, Co, C

and N elements exist in the composite in different chemical states by analyzing the full spectrum of the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite [23]. High-resolution XPS spectra is obtained by fitting spectra of each element. In Fig. 3 b, two peaks appear in the high-resolution XPS spectrum of Co 2p, with binding energy of 780.8 eV and 795.9 eV , which are attributed to 2 p orbital peak of

{Co}^{3 +}

. Additionally, the two peaks located at 781.7 eV and 796.8 eV are assigned to 2 p orbital peak of

{Co}^{2 +}

[9,24]. Meanwhile, the two peaks at 785.9 eV and 802.5 eV are caused by satellite peaks of Co. In the high-resolution XPS spectrum of Zn 2 p (Fig. 3 d ), a characteristic peak appears at 1022 eV , which is derived from the spin peak of the

Zn 2 p^{1 / 2}

orbital. A peak appears at 1045 eV is resulted from spin peak of the Zn

2 p^{3 / 2}

orbital and the energy gap is 23.1 eV [25-27].

O 1 s, O 1, O 2

and O 3 peaks can be found in the composite in the O 1 s spectrum (Fig. 3 c ) [28-30]. A characteristic peak of O1 appears at the binding energy of 529.8 eV , which represents the characteristic peak of metal oxide and indicating the formation of

Zn - O

and

Co - O

bonds inside the composite, thus confirming the existence of metal oxide. The O2 peak appears at the binding energy of 531.2 eV , which is resulted from adsorption of hydroxyl groups on surface of the composite. In addition, O3 peak at 532.3 eV is caused by oxygen lattice defect deficiency in the mixed metal oxide. In the high-resolution XPS spectrum of N 1 s , the characteristic peak at 398.5 eV is attributed to pyridine N in the carbon nanofibers and a strong characteristic peak appears at 399.6 eV is caused by pyrrole N in the carbon nanofibers [31]; A weak peak is located at 400.8 eV , which is assigned to the presence of graphite N in carbon nanofibers, as presented in Fig. 3 e. The C 1 s spectrum (Figure S 2 b ) indicates the characteristic peak of carbon

C = C / C - C

at 484.8 eV , and the characteristic peak at 286.0 eV is resulted from the

C - O

bond [32,33]. In addition, a characteristic peak at 288.8 eV belongs to the

C = O

bond [20]. The result further shows that the

{ZnCo}_{2} O_{4}

is formed in the composite, and the presence of a large amount of pyridine N and pyrrole N in the carbon nanofibers is beneficial to increase conductivity of the composite.
通过 X 射线光电子能谱研究了

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的元素价态。通过分析

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的全光谱，可以明显看出

Zn, O, Co, C

和 N 元素以不同的化学态存在于复合材料中[23]。通过拟合各元素的光谱，可获得高分辨率的 XPS 光谱。在图 3 b 中，Co 2p 的高分辨率 XPS 光谱中出现了两个峰，结合能分别为 780.8 eV 和 795.9 eV，这两个峰归因于

{Co}^{3 +}

的 2 p 轨道峰。此外，位于 781.7 eV 和 796.8 eV 的两个峰属于

{Co}^{2 +}

的 2 p 轨道峰 [9,24]。在 Zn 2 p 的高分辨率 XPS 光谱中（图 3 d），一个特征峰出现在 1022 eV 处，它来自于

Zn 2 p^{1 / 2}

轨道的自旋峰。在 1045 eV 处出现的峰值来自 Zn

2 p^{3 / 2}

轨道的自旋峰，能隙为 23.1 eV [25-27]。

O 1 s, O 1, O 2

和 O 3 峰可以在 O 1 s 光谱（图 3 c ）的复合材料中找到 [28-30]。O1 的特征峰出现在结合能 529.8 eV 处，代表了金属氧化物的特征峰，表明在复合材料内部形成了

Zn - O

和

Co - O

键，从而证实了金属氧化物的存在。O2 峰出现在 531.2 eV 的结合能处，这是复合材料表面吸附羟基的结果。此外，532.3 eV 处的 O3 峰是由于混合金属氧化物中的氧晶格缺陷造成的。在 N 1 s 的高分辨率 XPS 光谱中，398.5 eV 处的特征峰是由混合金属氧化物中的氧晶格缺陷引起的。如图 3 e 所示，在 399.6 eV 处出现了一个强特征峰，是碳纳米纤维中的吡咯 N 所致[31]；在 400.8 eV 处出现了一个弱峰，是碳纳米纤维中的石墨 N 所致。C 1 s 光谱（图 S 2 b）显示，碳

C = C / C - C

的特征峰位于 484.8 eV，而

C - O

键产生的特征峰位于 286.0 eV [32,33]。此外，288.8 eV 处的特征峰属于

C = O

键 [20]。结果进一步表明，复合材料中形成了

{ZnCo}_{2} O_{4}

键，而碳纳米纤维中大量吡啶 N 和吡咯 N 的存在有利于提高复合材料的导电性。

In order to further test the microstructure of the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite to study its influence on the electrochemical performance, the BET specific surface area was analyzed by

N_{2}

adsorptiondesorption isotherm. The corresponding BET specific surface area can be obtained as

27.35 m^{2} / g

(Fig. 3 f ). Besides, the pore size distribution curve of composite is shown in illustration and the pore size distribution range is

1.74 nm - 169.74 nm

. The abundant porosity in the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite is beneficial to increasing the active sites for lithium ions lithiation and delithiation inside the electrode. Meanwhile, the porosity of the composite is beneficial to promote penetration of lithium ions electrolyte and promote rapid transmission of lithium ions, thereby accelerating the electrochemical reaction.
为了进一步测试

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料的微观结构，研究其对电化学性能的影响，采用

N_{2}

吸附-吸附等温线分析了 BET 比表面积。相应的 BET 比表面积可求得

27.35 m^{2} / g

（图 3 f）。此外，复合材料的孔径分布曲线如图所示，其孔径分布范围为

1.74 nm - 169.74 nm

。

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料中丰富的孔隙率有利于增加电极内部锂离子锂化和脱锂的活性位点。同时，复合材料的多孔性有利于促进锂离子电解液的渗透，促进锂离子的快速传输，从而加速电化学反应。

To evaluate electrochemical performance of the

{ZnCo}_{2} O_{4}

@carbon nanofiber composite, which was used as an electrode active material. The

{ZnCo}_{2} O_{4} @

carbon nanofiber composite was mixed with a conductive agent (NW-CNTs) and a binder (CMC) to prepared electrode. Afterwards, the electrode was assembled into a CR-2032 battery in a vacuum glove box. The mechanism of

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode used for lithium ions storage was studied by cyclic voltammetry (CV) curve, which is measured by a three-electrode measurement on the electrochemical workstation. The test voltage range is between 0.01 and 3 V and corresponding scanning speed is

0.1 mV s^{- 1}

. The result is presented in Fig. 4 a . In the first cathodic scan, a broad reduction peak appears between 0.71 V , which is attributed to the fact that

{ZnCo}_{2} O_{4}

is reduced to elemental Zn , Co and

{Li}_{2} O

when lithium ions are inserted into the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite [34-36]. additionally, a sharp peak appears at a potential close to 0.34 V , which is assigned to
评估用作电极活性材料的

{ZnCo}_{2} O_{4}

@ 碳纳米纤维复合材料的电化学性能。将

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料与导电剂（NW-CNTs）和粘合剂（CMC）混合，制备出电极。然后，在真空手套箱中将电极组装成 CR-2032 电池。通过循环伏安法（CV）曲线研究了

{ZnCo}_{2} O_{4} @

碳纳米管电极用于锂离子存储的机理。测试电压范围为 0.01 至 3 V，相应的扫描速度为

0.1 mV s^{- 1}

。结果如图 4 a 所示。在第一次阴极扫描中，0.71 V 之间出现了一个宽的还原峰，这是由于当锂离子插入

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料时，

{ZnCo}_{2} O_{4}

被还原成 Zn、Co 和

{Li}_{2} O

元素 [34-36]。

Fig. 4. (a) CV curves of

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode; (b) discharge and charge curves of

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode; © Rate capability of
图 4. (a)

{ZnCo}_{2} O_{4} @

纳米碳纤维电极的 CV 曲线；(b)

{ZnCo}_{2} O_{4} @

纳米碳纤维电极的放电和充电曲线；© 纳米碳纤维电极的速率能力；(c)

{ZnCo}_{2} O_{4} @

纳米碳纤维电极的放电和充电曲线。

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode at

0.5 A g^{- 1}

; (f) Cycle capability of

Zn @ Co @

carbon nanofiber electrode and

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode at

1 A g^{- 1}

(g, h)

The images of electrode picture after rate performance test at different magnifications.

0.5 A g^{- 1}

时的

{ZnCo}_{2} O_{4} @

纳米碳纤维电极；（f）

1 A g^{- 1}

时的

Zn @ Co @

纳米碳纤维电极和

{ZnCo}_{2} O_{4} @

纳米碳纤维电极的循环能力。

(g, h)

不同放大倍数下的速率性能测试后的电极图片。
lithium ions intercalation into amorphous carbon and formation of solid electrolyte interphase (SEI) layers [37,38]. Two broad weak peaks appearing at 1.63 V and 2.10 V can be observed in the first anode scan, which are ascribed to the deintercalation of lithium ions from the composite and Co and Zn are oxidized to form

{Co}^{2 +}

and

{Zn}^{2 +}

[39-42]. Besides, the weak redox peak appearing in the CV curve is ascribed to the large amount of amorphous structure in the composite, which leads to the weakening of the redox peak during the cyclic voltammetry scan. After that, the CV curves shown well overlap, which indicating that the lithium ions can be inserted and extracted inside the

{ZnCo}_{2} O_{4}

@carbon nanofiber electrode stably [43].
锂离子插层进入无定形碳并形成固态电解质相间层 (SEI)[37,38]。在第一次阳极扫描中可以观察到两个宽弱峰，分别出现在 1.63 V 和 2.10 V，这两个峰是由于锂离子从复合材料中脱插，钴和锌被氧化形成

{Co}^{2 +}

和

{Zn}^{2 +}

[39-42]。此外，CV 曲线中出现的微弱氧化还原峰是由于复合材料中存在大量无定形结构，导致在循环伏安扫描过程中氧化还原峰减弱。之后，CV 曲线显示出很好的重合，这表明锂离子可以稳定地在

{ZnCo}_{2} O_{4}

@ 碳纳米纤维电极内部插入和提取[43]。

To evaluate lithium ion storage performance of

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode, a constant current charge and discharge test was performed to test the half-cell assembly of

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode. The first three cycles of charge and discharge curves at 0.1 A

g^{- 1}

are shown in Fig. 4 b. A discharge capacity of

1545 mA h g^{- 1}

can be delivered during the first discharge, a capacity of

1071 mA h^{- 1}

can be obtained during the first charge and the corresponding coulombic efficiency is

69.31 %

. Besides, the

30.69 %

of the capacity lost during the first cycle due to insertion of small amount of lithium ions into the amorphous carbon of

{ZnCo}_{2} O_{4} @

carbon nanofibers and formation of dead lithium, which cannot be extracted from the composite in time during subsequent charging. Additionally, most of the capacity loss is resulted from irreversible decomposition of the organic electrolyte during the first cycling and formation of solid electrolyte film (SEI) film on the electrode surface [44-46]. In addition, the electrode shows high reversible capacity (charge capacity of

1015 mA h g^{- 1}

and discharge capacity of

1053 mA h g^{- 1}

) during the second cycling, the corresponding coulombic efficiency is

96.33 %

, which indicates that the insertion and extraction reaction of lithium ions in the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode tend to be stable. Moreover, in the third cycle, a capacity of

1014.927 mA h g^{- 1}

can be delivered with a coulombic efficiency of

98.46 %

. Compared with

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode, the Zn@Co@carbon nanofiber electrode shows an inferior capacity and presented in Fig. S

3 b

.
为了评估

{ZnCo}_{2} O_{4} @

碳纳米纤维电极的锂离子存储性能，对

{ZnCo}_{2} O_{4} @

碳纳米纤维电极的半电池组件进行了恒流充放电测试。图 4 b 中显示了在 0.1 A

g^{- 1}

下的前三个循环充放电曲线。在第一次放电过程中，可提供

1545 mA h g^{- 1}

的放电容量，在第一次充电过程中，可获得

1071 mA h^{- 1}

的容量，相应的库仑效率为

69.31 %

。此外，

30.69 %

的容量损失是由于少量锂离子插入

{ZnCo}_{2} O_{4} @

碳纳米纤维的无定形碳中并形成死锂，在后续充电过程中无法及时从复合材料中提取。此外，大部分容量损失是由于有机电解质在第一次循环过程中发生不可逆分解以及在电极表面形成固态电解质膜（SEI）造成的[44-46]。此外，该电极在第二次循环中显示出较高的可逆容量（充电容量为

1015 mA h g^{- 1}

，放电容量为

1053 mA h g^{- 1}

），相应的库仑效率为

96.33 %

，这表明锂离子在

{ZnCo}_{2} O_{4} @

碳纳米纤维电极中的插入和萃取反应趋于稳定。此外，在第三个循环中，可提供

1014.927 mA h g^{- 1}

的容量，库仑效率为

98.46 %

。与

{ZnCo}_{2} O_{4} @

碳纳米纤维电极相比，Zn@Co@碳纳米纤维电极的容量较低，见图 S

3 b

。

The rate performance of the

Zn @ C o @ c a r b o n

nanofiber electrode and

{ZnCo}_{2} O_{4}

@carbon nanofiber electrode is obtained by testing the battery under different current densities, as presented in Fig. 4 c, d. The Zn@Co@carbon nanofiber electrode delivers specific capacity of

875.357 mA h^{- 1}, 752.894 mAh g^{- 1}, 673.527 mAh g^{- 1}, 497.509 mA h

g^{- 1}

and

376.75 mA h g^{- 1}

for 10, 10, 27, 20 and 11 cycles at current of

0.1 A g^{- 1}, 0.3 A g^{- 1}, 0.5 A g^{- 1}, 1 {Ag}^{- 1}

and

2 A g^{- 1}

. In addition, a specific capacity of

663.387 mA h^{- 1}

can be delivered when current density is adjusted back to

0.1 {Ag}^{- 1}

again and maintain 754.528 mA h

g^{- 1}

after 10 cycles. In contrast, the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode demonstrates more excellent rate performance, which can deliver a capacity of

1053.881 mA h g^{- 1}, 893.955 mA h^{- 1}, 778.323 mA h g^{- 1}

684.384 mA h^{- 1}

and

519.642 mAh g^{- 1}

0.1 {Ag}^{- 1}, 0.3 A g^{- 1}, 0.5 A

g^{- 1}, 1 {Ag}^{- 1}

and

2 A g^{- 1}

. Furthermore, a reversible capacity of 505.145

mA g^{- 1}

can be achieved at

3 {Ag}^{- 1}

and hold

884.046 mA {hg}^{- 1}

when the current density returns to

0.1 {Ag}^{- 1}

again, and capacity returns to

946.998 mA h g^{- 1}

after 10 cycles. More surprisingly, when the current density is controlled to

0.2 A g^{- 1}

again, the electrode can maintain a reversible capacity of

714 mA h^{- 1}

after 250 cycles. The results confirm that the

{ZnCo}_{2} O_{4} @ c a r b o n

nanofiber electrode has superior rate capability and cycle stability. Besides, in Fig.

4 g

and

h

, the nanofiber maintains after the rate performance. (The fiber structure is no very obvious due to grind the power and mixed with acetylene black and sodium carboxymethylcellulose during prepared for electrode).
如图 4 c、d 所示，通过测试不同电流密度下的电池，得到

Zn @ C o @ c a r b o n

纳米纤维电极和

{ZnCo}_{2} O_{4}

@ 碳纳米纤维电极的速率性能。Zn@Co@ 碳纳米纤维电极在

0.1 A g^{- 1}, 0.3 A g^{- 1}, 0.5 A g^{- 1}, 1 {Ag}^{- 1}

和

2 A g^{- 1}

电流下循环 10 次、10 次、27 次、20 次和 11 次时，比容量分别为

875.357 mA h^{- 1}, 752.894 mAh g^{- 1}, 673.527 mAh g^{- 1}, 497.509 mA h

g^{- 1}

和

376.75 mA h g^{- 1}

。此外，当电流密度再次调回

0.1 {Ag}^{- 1}

时，可提供

663.387 mA h^{- 1}

的比容量，并在 10 个循环后保持 754.528 mA h

g^{- 1}

的比容量。相比之下，

{ZnCo}_{2} O_{4} @

碳纳米纤维电极的速率性能更为出色，在

0.1 {Ag}^{- 1}, 0.3 A g^{- 1}, 0.5 A

g^{- 1}, 1 {Ag}^{- 1}

和

2 A g^{- 1}

条件下可输出

1053.881 mA h g^{- 1}, 893.955 mA h^{- 1}, 778.323 mA h g^{- 1}

、

684.384 mA h^{- 1}

和

519.642 mAh g^{- 1}

的容量。此外，当电流密度再次回到

0.1 {Ag}^{- 1}

时，在

3 {Ag}^{- 1}

和保持

884.046 mA {hg}^{- 1}

时可实现 505.145

mA g^{- 1}

的可逆容量，10 个循环后容量恢复到

946.998 mA h g^{- 1}

。更令人惊奇的是，当电流密度再次控制在

0.2 A g^{- 1}

时，电极在 250 个循环后仍能保持

714 mA h^{- 1}

的可逆容量。结果证实，

{ZnCo}_{2} O_{4} @ c a r b o n

纳米纤维电极具有卓越的速率能力和循环稳定性。此外，在图

4 g

和

h

中，纳米纤维在保持速率性能后。(由于在制备电极时研磨了功率并与乙炔黑和羧甲基纤维素钠混合，纤维结构不是很明显）。

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode at

0.5 A g^{- 1}

was first tested to verify its actual performance (Fig. 4 e). Initial discharge specific capacity of Zn Co @carbon nanofiber electrode is

687.261 mA h g^{- 1}

, and corresponding coulombic efficiency is

89.19 %

. In addition, the electrode has good cycle stability, which still maintains

437.501 mA h^{- 1}

after 270 cycles with a coulomb efficiency of

99.7 %

and no obvious attenuation. As a comparison,

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode exhibits more excellent cycle performance. In the first cycle process, the
首先测试了

0.5 A g^{- 1}

处的

{ZnCo}_{2} O_{4} @

纳米碳纤维电极，以验证其实际性能（图 4 e）。Zn Co @碳纳米纤维电极的初始放电比容量为

687.261 mA h g^{- 1}

，相应的库仑效率为

89.19 %

。此外，该电极具有良好的循环稳定性，循环 270 次后仍能保持

437.501 mA h^{- 1}

，库仑效率为

99.7 %

，且无明显衰减。相比之下，

{ZnCo}_{2} O_{4} @

纳米碳纤维电极的循环性能更为出色。在第一个循环过程中

69.36 %

. Besides, a capacity of

876.883 mA h^{- 1}

was delivered in second cycle and capacity decays slightly during subsequent cycle. Additionally, the electrode exhibits a capacity of

583.384 mA h^{- 1}

after 270 cycles, which is higher than

Zn @ C o @ c a r b o n

nanofiber electrode. Moreover, the electrode exhibits outstanding cycle performance and it even remains

447.165 mA h g^{- 1}

after 500 cycles. The excellent cycle performance of

{ZnCo}_{2} O_{4}

@carbon nanofiber is attributed to the stable nanofiber structure, which results unstable intercalation and deintercalation reactions of lithium ions.

69.36 %

。此外，第二个循环的容量为

876.883 mA h^{- 1}

，随后的循环中容量略有下降。此外，该电极在循环 270 次后显示出

583.384 mA h^{- 1}

的容量，高于

Zn @ C o @ c a r b o n

纳米纤维电极。此外，该电极还具有出色的循环性能，甚至在 500 次循环后仍能保持

447.165 mA h g^{- 1}

。

{ZnCo}_{2} O_{4}

@碳纳米纤维优异的循环性能归功于其稳定的纳米纤维结构，这种结构导致了锂离子不稳定的插层和脱插层反应。

Furthermore, the long-cycle performance of the

Zn @ Co @ c a r b o n

nanofiber electrode and

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode at 1 A

g^{- 1}

was tested to evaluated its cycle stability at high current density, the
此外，还测试了

Zn @ Co @ c a r b o n

纳米纤维电极和

{ZnCo}_{2} O_{4} @

碳纳米纤维电极在 1 A

g^{- 1}

电流密度下的长循环性能，以评估其在高电流密度下的循环稳定性。

hibits a stable capacity of

420.592 mA h g^{- 1}

in initial cycle and maintain a reversible capacity of

458.435 mA h^{- 1}

for 314 cycles. In contrast, the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode exhibits superior lithium ion storage performance, which delivers a stable reversible capacity of

898.991 mA h g^{- 1}

in initial cycle, afterwards, the electrode capacity decays slowly and the capacity decays to

437.176 mA h g^{- 1}

after 200 cycles. After that, the capacity of the electrode tends to stabilize without significant attenuation, which holds a capacity of

454.542 mA h g^{- 1}

after 314 cycles, even retain

421.477 mA h^{- 1}

for 518 cycles. The results indicates that the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode can maintain a high capacity for stable cycling at a large current density, which is ascribed to the

{ZnCo}_{2} O_{4} @

carbon nanofiber composite can maintain stable structure when lithium ions are rapidly intercalated and deintercalated and the active sites do not accumulate.

420.592 mA h g^{- 1}

碳纳米纤维电极在初始循环中具有

420.592 mA h g^{- 1}

的稳定容量，并在 314 个循环中保持

458.435 mA h^{- 1}

的可逆容量。相比之下，

{ZnCo}_{2} O_{4} @

碳纳米纤维电极表现出更优越的锂离子存储性能，在初始循环中可提供

898.991 mA h g^{- 1}

的稳定可逆容量，之后电极容量缓慢衰减，200 次循环后容量衰减至

437.176 mA h g^{- 1}

。之后，电极的容量趋于稳定，没有明显衰减，在 314 个循环后容量保持在

454.542 mA h g^{- 1}

，甚至在 518 个循环后仍保持

421.477 mA h^{- 1}

。结果表明，

{ZnCo}_{2} O_{4} @

碳纳米纤维电极能在大电流密度下保持高容量稳定循环，这归功于

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料能在锂离子快速插层和脱插层时保持稳定的结构，活性位点不会堆积。

The influence of the internal impedance of the battery on the electrochemical performance of the Zn@Co@carbon nanofiber electrode and

{ZnCo}_{2} O_{4} @ c a r b o n

nanofiber electrode at different current densities after various cycles was studied by electrochemical impedance spectroscopy (EIS), as shown in Fig. 5 and Fig. S4. The diameter of the semicircle is determined by charge transfer resistance (

R_{c t}

) at interface between electrode and electrolyte. Smaller

R_{ct}

is related to smaller the diameter of the semicircle, which indicates that the electrons can be transferred inside the electrode quickly and accelerating the insertion/ extraction of lithium ions. Besides, diffusion rate of lithium ions inside electrode is related to slope of the inclined straight line and the rapid lithium ions diffusion can accelerate the electrochemical reaction. It can be observed that the

R_{ct}

of the freshly assembled battery is

140 Ω

as shown in Fig. 5 a. The

R_{ct}

of the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode after 135 cycles at

0.5 A g^{- 1}

is significantly reduces to

17 Ω

, as presented in Fig. 5 b. Additionally, EIS spectrum of the electrode after 300 cycles at

1 {Ag}^{- 1}

was performed and the

R_{ct}

also greatly reduces to

21 Ω

(Fig. 5 c ). The small

R_{c t}

results in the rapid transfer of electrons, so that the lithium ions can participate in the electrochemical reaction quickly inside the battery [47].
如图 5 和图 S4 所示，通过电化学阻抗谱（EIS）研究了电池内部阻抗对 Zn@Co@carbon 纳米纤维电极和

{ZnCo}_{2} O_{4} @ c a r b o n

纳米纤维电极在不同电流密度下不同循环后的电化学性能的影响。半圆的直径由电极和电解质界面上的电荷转移电阻（

R_{c t}

）决定。

R_{ct}

越小，半圆的直径就越小，这表明电子可以在电极内部快速转移，从而加速了锂离子的插入/提取。此外，锂离子在电极内部的扩散速度与倾斜直线的斜率有关，锂离子的快速扩散可以加速电化学反应。如图 5 a 所示，可以观察到刚组装好的电池的

R_{ct}

为

140 Ω

，而

{ZnCo}_{2} O_{4} @

碳纳米纤维电极的

R_{ct}

在

0.5 A g^{- 1}

循环 135 次后显著降低到

17 Ω

，如图 5 b 所示。此外，对在

1 {Ag}^{- 1}

下循环 300 次后的电极进行了 EIS 谱分析，发现

R_{ct}

也大大降低为

21 Ω

（图 5 c）。较小的

R_{c t}

导致电子快速转移，从而使锂离子能够快速参与电池内部的电化学反应 [47]。

The electrochemical reaction kinetics of the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode is test at various current densities and as shown in Fig. 6. Fig. 6a shows that CV curves maintain similar shapes, the cathodic peaks and anodic peaks transfer to lower and higher potentials at sweep rates of

0.1 - 2 mV s^{- 1}

, which demonstrates that the electrode keeps smaller polarization at different sweep rates. In general, electrochemical behavior of lithium-ion storage is divided into surface capacitive behavior and diffusion-controlled insertion process. The peak current (

i

) vs sweep rate

(v)

observe the following relationships:
如图 6 所示，测试了

{ZnCo}_{2} O_{4} @

碳纳米纤维电极在不同电流密度下的电化学反应动力学。图 6a 显示，CV 曲线保持相似的形状，在

0.1 - 2 mV s^{- 1}

的扫描速率下，阴极峰和阳极峰向更低和更高的电位转移，这表明电极在不同的扫描速率下保持较小的极化。一般来说，锂离子储能的电化学行为分为表面电容行为和扩散控制的插入过程。峰值电流 (

i

) 与扫描速率

(v)

的关系如下：

i = a v^{b}

\log (i) = b \log (v) + \log (a)

Herein, a and b are constants. The values of slope b are determined by electrochemical behavior. The diffusion-controlled insertion process is
其中，a 和 b 是常数。斜率 b 的值由电化学行为决定。扩散控制的插入过程为

Fig. 5. EIS spectrum of the

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode (a) in the initial state; (b) at

0.5 {Ag}^{- 1}

1 A g^{- 1}

for 300 cycles.
图 5.

{ZnCo}_{2} O_{4} @

碳纳米纤维电极 (a) 初始状态；(b)

0.5 {Ag}^{- 1}

循环 135 次；©

1 A g^{- 1}

循环 300 次的 EIS 光谱。

Fig. 6. Kinetic analysis of

{ZnCo}_{2} O_{4}

@carbon nanofiber electrode in lithium-ion storage at sweep rates of

0.1 - 2 mV s

. a) CV curves. b) b values of log (peak current) vs.

\log

(sweep rate) plots at corresponding cathodic and anodic peaks range. c) CV curve and capacitance contribution (olive area) at

0.2 mV s^{- 1}

. d) Capacitance contribution ratio under different sweep rates.
图 6.a) CV 曲线；b) 在相应的阴极和阳极峰值范围内，对数（峰值电流）与

\log

（扫描速率）图的 b 值；c)

0.2 mV s^{- 1}

时的 CV 曲线和电容贡献率（橄榄形面积）；d) 不同扫描速率下的电容贡献率。
dominated by the electrochemical behavior when the

b

value is close to 0.5. The lithium-ion storage mechanism is dominated by surface capacitive behavior when b value is close to 1 . Herein, b value corresponding to the cathodic and anodic peaks are 0.72 and 0.61 (Fig. 6b), respectively, which are both close to 0.5 , indicating electrochemical behavior controlled the electrochemical behavior of the lithium-ion storage. The capacitive contribution proportion of the lithium-ion storage can be calculated by following formula:
当

b

值接近 0.5 时，锂离子存储机制以电化学行为为主。当 b 值接近 1 时，锂离子存储机制以表面电容行为为主。这里，阴极峰和阳极峰对应的 b 值分别为 0.72 和 0.61（图 6b），均接近 0.5，表明电化学行为控制了锂离子存储的电化学行为。锂离子储能的电容贡献比例可按下式计算：

i = k_{1} v + k_{2} v^{0.5}

Where

k_{1}

and

k_{2}

are parameters at a given potential. The current

i

can be further assigned to surface capacitive behavior

(k_{1} v)

and diffusion- controlled insertion process

(k_{2} v^{0.5})

. The percentage of pseudocapacitance contribution at the same potential can be obtained by above formula (pseudocapacitance

= k_{1} v / (k_{1} v + k_{2} v^{0.5})

. The capacitance contribution of the electrode is

66.2 %

at the sweep rate of

0.2 mV s^{- 1}

, as presented in Fig. 6c. The detailed capacitive contribution of the lithiumion storage at various sweep rates is illustrated in Fig. 6d.
其中

k_{1}

和

k_{2}

是给定电位下的参数。电流

i

可进一步归因于表面电容行为

(k_{1} v)

和扩散控制插入过程

(k_{2} v^{0.5})

。相同电位下的伪电容贡献百分比可通过上式求得（伪电容

= k_{1} v / (k_{1} v + k_{2} v^{0.5})

。如图 6c 所示，在扫频速率为

0.2 mV s^{- 1}

时，电极的电容贡献率为

66.2 %

。图 6d 显示了不同扫描速率下锂离子存储的详细电容贡献。

4. Conclusion 4.结论

The

{ZnCo}_{2} O_{4} @

carbon nanofiber composite was successfully prepared by electrospinning, high-temperature annealing and follow by low-temperature oxidation, which avoids the structural degradation
通过电纺丝、高温退火和低温氧化，成功制备了

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料，避免了结构退化
that occurs directly during air oxidation. The active sites of

{ZnCo}_{2} O_{4}

are embedded in the carbon nanofibers with nanoclusters. Additionally, a large number of heteroatoms N in the carbon nanofiber is beneficial to improve the conductivity and lithium ion affinity. The stable structure is conducive to stable intercalation and deintercalation of lithium ions in the electrode. Besides, the large specific surface area can provide a large contact area for the electrode and the electrolyte, which in turn provides more active sites. Benefited from the above advantages,

{ZnCo}_{2} O_{4} @

carbon nanofiber electrode has excellent rate performance, which has a high capacity of

1071 mA h^{- 1}

0.1 {Ag}^{- 1}

, outstanding rate capability of

505 mA h g^{- 1}

3 {Ag}^{- 1}

and maintain

714 mA h g^{- 1}

after 250 cycles at

0.2 A g^{- 1}

after rate performance test. Furthermore, the electrode shows an outstanding long-cycle performance, which can remain a capacity of

447.165 mA h^{- 1}

for 500 cycles at

0.5 A g^{- 1}

and 421.477 mA

h g^{- 1}

for 518 cycles at

1 A g^{- 1}

. The result indicates that

{ZnCo}_{2} O_{4} @

carbon nanofiber composite has broad prospects for application in advanced energy storage.
在空气氧化过程中直接发生。

{ZnCo}_{2} O_{4}

的活性位点以纳米团簇的形式嵌入碳纳米纤维中。此外，碳纳米纤维中大量的杂原子 N 有利于提高导电性和锂离子亲和性。稳定的结构有利于锂离子在电极中的稳定插层和脱插层。此外，大的比表面积可为电极和电解质提供大的接触面积，从而提供更多的活性位点。得益于上述优点，

{ZnCo}_{2} O_{4} @

纳米碳纤维电极具有优异的速率性能，在

0.1 {Ag}^{- 1}

条件下具有

1071 mA h^{- 1}

的高容量，在

3 {Ag}^{- 1}

条件下具有

505 mA h g^{- 1}

的出色速率能力，并且在速率性能测试后，在

0.2 A g^{- 1}

条件下经过 250 次循环后仍能保持

714 mA h g^{- 1}

。此外，该电极还表现出出色的长循环性能，在

0.5 A g^{- 1}

下循环 500 次仍能保持

447.165 mA h^{- 1}

的容量，在

1 A g^{- 1}

下循环 518 次仍能保持 421.477 mA

h g^{- 1}

的容量。结果表明，

{ZnCo}_{2} O_{4} @

碳纳米纤维复合材料在先进储能领域具有广阔的应用前景。

Declaration of competing interest
利益冲突声明

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
作者声明，他们没有任何可能会影响本文所报告工作的已知经济利益或个人关系。

Acknowledgment 鸣谢

This work was financially supported by Joint Fund of the National Natural Science Foundation of China (No. U1833118), Cooperation Project between Sichuan University and Yibin City (2020CDYB-5) and Engineering characteristic team of Sichuan University (2020SCUNG122).
本研究得到了国家自然科学基金联合基金（U1833118）、四川大学与宜宾市合作项目（2020CDYB-5）和四川大学工程特色团队（2020SCUNG122）的资助。

Appendix A. Supplementary data
附录 A.补充数据

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ceramint.2023.01.174.
本文的补充数据可在线查阅：https://doi. org/10.1016/j.ceramint.2023.01.174。

References 参考资料

[1] X. Li, P. Yan, X. Xiao, J.H. Woo, C. Wang, J. Liu, J.G. Zhang, Design of porous Si/ C-graphite electrodes with long cycle stability and controlled swelling, Energy Environ. Sci. 10 (2017) 1427-1434.
[1] X. Li, P. Yan, X. Xiao, J.H. Woo, C. Wang, J. Liu, J.G. Zhang, Design of porous Si/ C-graphite electrodes with long cycle stability and controlled swelling, Energy Environ.10 (2017) 1427-1434.
[2] D. Chen, C. Feng, Y. Han, B. Yu, W. Chen, Z. Zhou, N. Chen, J.B. Goodenough, W. He, Origin of extra capacity in the solid electrolyte interphase near highcapacity iron carbide anodes for Li ion batteries, Energy Environ. Sci. 13 (2020) 2924-2937.
[2] D. Chen, C. Feng, Y. Han, B. Yu, W. Chen, Z. Zhou, N. Chen, J.B. Goodenough, W. He, Origin of extra capacity in the solid electrolyte interphase near high-capacity iron carbide anodes for Li ion batteries, Energy Environ.13 (2020) 2924-2937.
[3] S.S. Zhang, Identifying rate limitation and a guide to design of fast-charging Li-ion battery, Info 2 (2019) 942-949.
[4] Y. Liu, Y. Zhu, Y. Cui, Challenges and opportunities towards fast-charging battery materials, Nat. Energy 4 (2019) 540-550.
[4] Y. Liu, Y. Zhu, Y. Cui, Challenges and opportunities towards fast-charging battery materials, Nat.Energy 4 (2019) 540-550.
[5] X. Wang, Y.L. Ding, Y.P. Deng, Z. Chen, Ni-Rich/Co-Poor layered cathode for automotive Li-ion batteries: promises and challenges, Adv. Energy Mater. 10 (2020), 1903864.
[5] X. Wang, Y.L. Ding, Y.P. Deng, Z. Chen, Ni-Rich/Co-Poor layered cathode for automotive Li-ion batteries: promises and challenges, Adv. Energy Mater.10 (2020), 1903864.
[6] R. Hu, Y. Ouyang, T. Liang, X. Tang, B. Yuan, J. Liu, L. Zhang, L. Yang, M. Zhu, Inhibiting grain coarsening and inducing oxygen vacancies: the roles of Mn in achieving a highly reversible conversion reaction and a long life

{SnO}_{2}

-Mn-graphite ternary anode, Energy Environ. Sci. 10 (2017) 2017-2029.
[6] R. Hu, Y. Ouyang, T. Liang, X. Tang, B. Yuan, J. Liu, L. Zhang, L. Yang, M. Zhu, Inhibiting grain coarsening and inducing oxygen vacancies: the roles of Mn in achieving a highly reversible conversion reaction and a long life

{SnO}_{2}

-Mn-graphite ternary anode, Energy Environ.10 (2017) 2017-2029.
[7] H. Tang, M. Jiang, E. Ren, Y. Zhang, X. Lai, C. Cui, S. Jiang, M. Zhou, Q. Qin, R. Guo, Integrate electrical conductivity and

{Li}^{+}

ion mobility into hierarchical heterostructure

{Ti}_{3} C_{2} @ CoO / ZnO

composites toward high-performance lithium ion storage, Energy 212 (2020), 118696.
[7] H. Tang, M. Jiang, E. Ren, Y. Zhang, X. Lai, C. Cui, S. Jiang, M. Zhou, Q. Qin, R. Guo, Integrate electrical conductivity and

{Li}^{+}

ion mobility into hierarchical heterostructure

{Ti}_{3} C_{2} @ CoO / ZnO

composites toward high-performance lithium ion storage, Energy 212 (2020), 118696.
[8] H. Tang, M. Jiang, Y. Zhang, X. Lai, C. Cui, H. Xiao, S. Jiang, E. Ren, Q. Qin, R. Guo, CNTs anchored on defective bimetal oxide

{NiCoO}_{2 - x}

microspheres for highperformance lithium-ion battery anode, Electrochim. Acta 354 (2020), 136760.
[8] H. Tang, M. Jiang, Y. Zhang, X. Lai, C. Cui, H. Xiao, S. Jiang, E. Ren, Q. Qin, R. Guo, CNTs anchored on defective bimetal oxide

{NiCoO}_{2 - x}

microspheres for highperformance lithium-ion battery anode, Electrochim.Acta 354 (2020), 136760.
[9] J. Deng, X. Yu, X. Qin, D. Zhou, L. Zhang, H. Duan, F. Kang, B. Li, G. Wang, Co-B nanoflakes as multifunctional bridges in

{ZnCo}_{2} O_{4}

micro-/nanospheres for superior lithium storage with boosted kinetics and stability, Adv. Energy Mater. 9 (2019), 1803612.
[9] J. Deng, X. Yu, X. Qin, D. Zhou, L. Zhang, H. Duan, F. Kang, B. Li, G. Wang, Co-B nanoflakes as multifunctional bridges in

{ZnCo}_{2} O_{4}

micro-/nanospheres for superior lithium storage with boosted kinetics and stability, Adv. Energy Mater.9 (2019), 1803612.
[10] H. Tang, R. Guo, M. Jiang, Y. Zhang, X. Lai, C. Cui, H. Xiao, S. Jiang, E. Ren, Q. Qin, Construction of

{Ti}_{3} C_{2}

MXene@C@SnS with layered rock stratum structure for high-performance lithium storage, J. Power Sources 462 (2020), 228152.
[10] H. Tang, R. Guo, M. Jiang, Y. Zhang, X. Lai, C. Cui, H. Xiao, S. Jiang, E. Ren, Q. Qin, Construction of

{Ti}_{3} C_{2}

MXene@C@SnS with layered rock stratum structure for high-performance lithium storage, J. Power Sources 462 (2020), 228152.
[11] X. Li, J. Wang, One-dimensional and two-dimensional synergized nanostructures for high-performing energy storage and conversion, Info 2 (2019) 3-32.
[11] X. Li, J. Wang, 用于高性能能量存储和转换的一维和二维协同纳米结构，Info 2 (2019) 3-32.
[12] Q. Han, X. Zhang, W. Zhang, Y. Li, Z. Zhang, Preparation of multifunctional structural P-CF@

{ZnCo}_{2} O_{4}

composites used as structural anode materials, J. Alloys Compd. 842 (2020), 155743.
[12] Q. Han, X. Zhang, W. Zhang, Y. Li, Z. Zhang, Preparation of multifunctional structural P-CF@

{ZnCo}_{2} O_{4}

composites used as structural anode materials, J. Alloys Compd.842 (2020), 155743.
[13] L. Wang, M. Zhen, F. Hu, H. Wang, H. Jia, M. Wei, Construction of threedimensional

{ZnCo}_{2} O_{4}

hierarchical nanocubes for enhanced lithium storage performances, Mater. Lett. 286 (2021), 129231.
[13] L. Wang, M. Zhen, F. Hu, H. Wang, H. Jia, M. Wei, Construction of threedimensional

{ZnCo}_{2} O_{4}

hierarchical nanocubes for enhanced lithium storage performances, Mater.286 (2021), 129231.
[14] W. Zhao, Z. Shi, Y. Qi, J. Cheng, The carbon-coated

{ZnCo}_{2} O_{4}

Nanowire arrays pyrolyzed from PVA for enhancing lithium storage capacity, Processes 8 (2020) 1501 .
[14] W. Zhao, Z. Shi, Y. Qi, J. Cheng, The carbon-coated

{ZnCo}_{2} O_{4}

Nanowire arrays pyrolyzed from PVA for enhancing lithium storage capacity, Processes 8 (2020) 1501 .
[15] H. Liang, J. Wu, M. Wang, H. Fan, Y. Zhang, Pseudocapacitance-dominated highperformance and stable lithium-ion batteries from MOF-derived spinel

{ZnCo}_{2} O_{4}

/ ZnO/C heterostructure anode, Dalton Trans. 49 (2020) 13311-13316.
[15] H. Liang, J. Wu, M. Wang, H. Fan, Y. Zhang, Pseudocapacitance-dominated highperformance and stable lithium-ion batteries from MOF-derived spinel

{ZnCo}_{2} O_{4}

/ ZnO/C heterostructure anode, Dalton Trans.49 (2020) 13311-13316.
[16] L. Li, Z. Xie, G. Jiang, Y. Wang, B. Cao, C. Yuan, Efficient laser-induced construction of oxygen-vacancy abundant nano-

{ZnCo}_{2} O_{4}

/porous reduced graphene oxide hybrids toward exceptional capacitive lithium storage, Small 16 (2020), e2001526.
[16] L. Li, Z. Xie, G. Jiang, Y. Wang, B. Cao, C. Yuan, Efficient laser-induced construction of oxygen-vacancy abundant nano-

{ZnCo}_{2} O_{4}

/porous reduced graphene oxide hybrids toward exceptional capacitive lithium storage, Small 16 (2020), e2001526.
[17] Z. Zhang, Y. Huang, X. Liu, X. Wang, P. Liu, Yolk-shell structured

{ZnCo}_{2} O_{4}

spheres anchored on reduced graphene oxide with enhance lithium/sodium storage performance, Electrochim. Acta 342 (2020), 136104.
[17] Z. Zhang, Y. Huang, X. Liu, X. Wang, P. Liu, Yolk-shell structured

{ZnCo}_{2} O_{4}

spheres anchored on reduced graphene oxide with enhance lithium/sodium storage performance, Electrochim.Acta 342 (2020), 136104.
[18] L. Zhang, S. Zhu, X. Li, H. Fang, L. Wang, Y. Song, X. Jia, 3D porous

{ZnCo}_{2} O_{4} @ NiO

on nickel foam as advanced electrodes for lithium storage, Ionics 26 (2019)

2157 - 2164

.
[18] L. Zhang, S. Zhu, X. Li, H. Fang, L. Wang, Y. Song, X. Jia, 3D porous

{ZnCo}_{2} O_{4} @ NiO

on nickel foam as advanced electrodes for lithium storage, Ionics 26 (2019)

2157 - 2164

.
[19] J. Yoon, H.S. Yang, B.S. Lee, W.R. Yu, Recent progress in coaxial electrospinning: new parameters, various structures, and wide applications, Adv. Mater. 30 (2018), e1704765.
[19] J. Yoon, H.S. Yang, B.S. Lee, W.R. Yu, Recent progress in coaxial electrospinning: new parameters, various structures, and wide applications, Adv. Mater.30 (2018), e1704765.
[20] J. Li, C. Chen, Y. Chen, Z. Li, W. Xie, X. Zhang, M. Shao, M. Wei, Polysulfide confinement and highly efficient conversion on hierarchical mesoporous carbon nanosheets for Li-S batteries, Adv. Energy Mater. 9 (2019), 1901935.
[20] J. Li, C. Chen, Y. Chen, Z. Li, W. Xie, X. Zhang, M. Shao, M. Wei, Polysulfide confinement and highly efficient conversion on hierarchical mesoporous carbon nanosheet for Li-S batteries, Adv. Energy Mater.9 (2019), 1901935.
[21] J. Bai, X. Li, G. Liu, Y. Qian, S. Xiong, Unusual Formation of

{ZnCo}_{2} O_{4}

3D hierarchical twin microspheres as a high-rate and ultralong-life lithium-ion battery anode material, Adv. Funct. Mater. 24 (2014) 3012-3020.
[21] J. Bai, X. Li, G. Liu, Y. Qian, S. Xiong, Unusual Formation of

{ZnCo}_{2} O_{4}

3D hierarchical twin microspheres as a highrate and ultralong-life lithium-ion battery anode material, Adv.Funct.Mater.24 (2014) 3012-3020.
[22] M.W. Liao, H.T. Jeng, T.P. Perng, Formation mechanism and bandgap reduction of GaN-ZnO solid-solution thin films fabricated by nanolamination of atomic layer deposition, Adv. Mater. (2022), e2207849.
[22] M.W. Liao, H.T. Jeng, T.P. Perng, Formation mechanism and bandgap reduction of GaN-ZnO solid-solution thin films fabricated by nanolamination of atomic layer deposition, Adv.(2022), e2207849.
[23] L. Zhao, K. Wang, W. Wei, L. Wang, W. Han, High-performance flexible sensing devices based on polyaniline/MXene nanocomposites, Info 1 (2019) 407-416.
[24] Z.Q. Liu, H. Cheng, N. Li, T.Y. Ma, Y.Z.

Su, {ZnCo}_{2} O_{4}

quantum dots anchored on nitrogen-doped carbon nanotubes as reversible oxygen reduction/evolution electrocatalysts, Adv. Mater. 28 (2016) 3777-3784.
[24] Z.Q. Liu, H. Cheng, N. Li, T.Y. Ma, Y.Z.

Su, {ZnCo}_{2} O_{4}

量子点锚定在掺氮碳纳米管上作为可逆氧还原/进化电催化剂，Adv. Mater.28 (2016) 3777-3784.
[25] J.-L. Yang, S.-X. Zhao, Y.-M. Lu, X.-T. Zeng, W. Lv, G.-Z. Cao, ZnS spheres wrapped by an ultrathin wrinkled carbon film as a multifunctional interlayer for long-life Li-S batteries, J. Mater. Chem. 8 (2020) 231-241.
[25] J.-L. Yang, S.-X. Zhao, Y.-M.Zhao, Y.-M. Lu, X.-T.Lu, X.-T. Zeng, W. Lv, G.-Z.ZnS spheres wrapped by an ultathin wrinked carbon film.Cao, ZnS spheres wrapped by an ultrathin wrinkled carbon film as a multifunctional interlayer for long-life Li-S batteries, J. Mater.Chem.8 (2020) 231-241.
[26] P. Zhou, M. Zhang, L. Wang, Q. Huang, Z. Su, P. Xu, R. Zou, X. Wang, C. Zeng, K. Ba, MOFs-derived flower-like hierarchically porous

Zn - Mn - Se / C

composite for extraordinary rate performance and durable anode of sodium-ion and potassiumion batteries, Small 18 (2022), e2203964.
[26] P. Zhou, M. Zhang, L. Wang, Q. Huang, Z. Su, P. Xu, R. Zou, X. Wang, C. Zeng, K. Ba, MOFs-derived flower-like hierarchically porous

Zn - Mn - Se / C

composite for extraordinary rate performance and durable anode of sodium-ion and potassiumion batteries, Small 18 (2022), e2203964.
[27] P. Zhou, M. Zhang, L. Wang, Q. Huang, Z. Su, L. Li, X. Wang, Y. Li, C. Zeng, Z. Guo, Synthesis and electrochemical performance of ZnSe electrospinning nanofibers as an anode material for lithium ion and sodium ion batteries, Front. Chem. 7 (2019) 569 .
[27] P. Zhou, M. Zhang, L. Wang, Q. Huang, Z. Su, L. Li, X. Wang, Y. Li, C. Zeng, Z. Guo, Synthesis and electrochemical performance of ZnSe electrospinning nanofibers as an anode material for lithium ion and sodium ion batteries, Front.Chem.7 (2019) 569 .
[28] D. Luo, G. Li, Y.P. Deng, Z. Zhang, J. Li, R. Liang, M. Li, Y. Jiang, W. Zhang, Y. Liu, W. Lei, A. Yu, Z. Chen, Synergistic engineering of defects and architecture in binary metal chalcogenide toward fast and reliable lithium-sulfur batteries, Adv. Energy Mater. 9 (2019), 1900228.
[28] D. Luo, G. Li, Y.P. Deng, Z. Zhang, J. Li, R. Liang, M. Li, Y. Jiang, W. Zhang, Y. Liu, W. Lei, A. Yu, Z. Chen, Synergistic engineering of defects and architecture in binary metal chalcogenide toward fast and reliable lithium-sulfur batteries, Adv. Energy Mater.9 (2019), 1900228.
[29] T. Ruan, B. Wang, Y. Yang, X. Zhang, R. Song, Y. Ning, Z. Wang, H. Yu, Y. Zhou, D. Wang, H. Liu, S. Dou, Interfacial and electronic modulation via localized sulfurization for boosting lithium storage kinetics, Adv. Mater. 32 (2020), e2000151.
[29] T. Ruan、B. Wang、Y. Yang、X. Zhang、R. Song、Y. Ning、Z. Wang、H. Yu、Y. Zhou、D. Wang、H. Liu、S. Dou, Interfacial and electronic modulation via localized sulfurization for boosting lithium storage kinetics, Adv. Mater.32 (2020), e2000151.
[30] Q.C. Wang, J.K. Meng, X.Y. Yue, Q.Q. Qiu, Y. Song, X.J. Wu, Z.W. Fu, Y.Y. Xia, Z. Shadike, J. Wu, X.Q. Yang, Y.N. Zhou, Tuning P2-structured cathode material by Na-site Mg substitution for Na-ion batteries, J. Am. Chem. Soc. 141 (2019)

840 - 848

.
[30] Q.C. Wang, J.K. Meng, X.Y. Yue, Q.Q. Qiu, Y. Song, X.J. Wu, Z.W. Fu, Y.Y. Xia, Z. Shadike, J. Wu, X.Q. Yang, Y.N. Zhou, Tuning P2-structured cathode material by Na-site Mg substitution for Na-ion batteries, J. Am. Chem.Chem.141 (2019)

840 - 848

.
[31] R. Wang, J. Yang, X. Chen, Y. Zhao, W. Zhao, G. Qian, S. Li, Y. Xiao, H. Chen, Y. Ye, G. Zhou, F. Pan, Highly dispersed cobalt clusters in nitrogen-doped porous carbon enable multiple effects for high-performance Li-S battery, Adv. Energy Mater. 10 (2020), 1903550.
[31] R. Wang, J. Yang, X. Chen, Y. Zhao, W. Zhao, G. Qian, S. Li, Y. Xiao, H. Chen, Y. Ye, G. Zhou, F. Pan, Highly dispersed cobalt clusters in nitrogen-doped porous carbon enable multiple effects for high-performance Li-S battery, Adv. Energy Mater.10 (2020), 1903550.
[32] Y. Hu, W. Chen, T. Lei, B. Zhou, Y. Jiao, Y. Yan, X. Du, J. Huang, C. Wu, X. Wang, Y. Wang, B. Chen, J. Xu, C. Wang, J. Xiong, Carbon quantum dots-modified interfacial interactions and ion conductivity for enhanced high current density performance in lithium-sulfur batteries, Adv. Energy Mater. 9 (2019), 1802955.
[32] Y. Hu, W. Chen, T. Lei, B. Zhou, Y. Jiao, Y. Yan, X. Du, J. Huang, C. Wu, X. Wang, Y. Wang, B. Chen, J. Xu, C. Wang, J. Xiong, Carbon quantum dots-modified interfacial interactions and ion conductivity for enhanced high current density performance in lithium-sulfur batteries, Adv. Energy Mater.9 (2019), 1802955.
[33] X. Lv, T. Lei, B. Wang, W. Chen, Y. Jiao, Y. Hu, Y. Yan, J. Huang, J. Chu, C. Yan, C. Wu, J. Wang, X. Niu, J. Xiong, An efficient separator with low Li-ion diffusion energy barrier resolving feeble conductivity for practical lithium-sulfur batteries, Adv. Energy Mater. 9 (2019), 1901800.
[33] X. Lv, T. Lei, B. Wang, W. Chen, Y. Jiao, Y. Hu, Y. Yan, J. Huang, J. Chu, C. Yan, C. Wu, J. Wang, X. Niu, J. Xiong, An efficient separator with low Li-ion diffusion energy barrier resolving feeble conductivity for practical lithium-sulfur batteries, Adv. Energy Mater.9 (2019), 1901800.
[34] B. Wang, X.-Y. Lu, Y. Tang, Synthesis of snowflake-shaped

{CO}_{3} O_{4}

with a high aspect ratio as a high capacity anode material for lithium ion batteries, J. Mater. Chem. 3 (2015) 9689-9699.
[34] B. Wang, X.-Y. Lu, Y. Tang, Synthesis of snowflake-shaped

{CO}_{3} O_{4}

with the high aspect ratio as high capacity anode material for lithium ion batteries, J. Mater.Lu, Y. Tang, Synthesis of snowflake-shaped

{CO}_{3} O_{4}

with a high aspect ratio as a high capacity anode material for lithium ion batteries, J. Mater.Chem.3 (2015) 9689-9699.
[35] F. Zou, X. Hu, Z. Li, L. Qie, C. Hu, R. Zeng, Y. Jiang, Y. Huang, MOF-derived porous

ZnO / {ZnFe}_{2} O_{4} / C

octahedra with hollow interiors for high-rate lithium-ion batteries, Adv. Mater. 26 (2014) 6622-6628.
[35] F. Zou, X. Hu, Z. Li, L. Qie, C. Hu, R. Zeng, Y. Jiang, Y. Huang, MOF-derived porous

ZnO / {ZnFe}_{2} O_{4} / C

octahedra with hollow interiors for high-rate lithium-ion batteries, Adv. Mater.26 (2014) 6622-6628.
[36] X.-B. Zhong, H.-Y. Wang, Z.-Z. Yang, B. Jin, Q.-C. Jiang, Facile synthesis of mesoporous

{ZnCo}_{2} O_{4}

coated with polypyrrole as an anode material for lithium-ion batteries, J. Power Sources 296 (2015) 298-304.
[36] X.-B.Zhong, H.-Y. Wang, Z.-Z.Wang, Z.-Z. Yang, B. Jin, Q.-C.Yang, B. Jin, Q.-C. Jiang, Facile synthesis mesoporous

{ZnCo}_{2} O_{4}

coated with polypyrrole as an anner.Jiang, Facile synthesis of mesoporous

{ZnCo}_{2} O_{4}

coated with polypyrrole as anode material for lithium-ion batteries, J. Power Sources 296 (2015) 298-304.
[37] J.F.S. Fernando, C. Zhang, Konstantin L. Firestein, J.Y. Nerkar, D.V. Golberg, ZnO quantum dots anchored in multilayered and flexible amorphous carbon sheets for
[37] J.F.S. Fernando、C. Zhang、Konstantin L. Firestein、J.Y. Nerkar、D.V. Golberg，ZnO 量子点锚定在多层柔性无定形碳片中，用于在多层柔性无定形碳片中形成 "量子点"。
high performance and stable lithium ion batteries, J. Mater. Chem. 7 (2019) 8460-8471.
高性能和稳定的锂离子电池，J. Mater.Chem.7 (2019) 8460-8471.
[38] Y. Li, J. Chen, M. Lu, Y. Peng, Y. Tan, X. Zhang, X. Lin, G. Ma, R.C. Krishna Reddy, Z. Xu, Y. Wu, Metal-organic framework-derived ultrafine

ZnO / {Co}_{3} ZnC

particles embedded in N -doped carbon concave-dodecahedron towards enhanced lithium storage, Chemelectrochem 9 (2022).
[38] Y. Li, J. Chen, M. Lu, Y. Peng, Y. Tan, X. Zhang, X. Lin, G. Ma, R.C. Krishna Reddy, Z. Xu, Y. Wu, Metal-organic framework-derived ultrafine

ZnO / {Co}_{3} ZnC

particles embedded in N -doped carbon concave-dodecahedron towards enhanced lithium storage, Chemelectrochem 9 (2022).
[39] Y. Luo, R. Guo, T. Li, F. Li, L. Meng, Z. Yang, Y. Wan, H. Luo, Conductive polypyrrole coated hollow

{NiCO}_{2} O_{4}

Microspheres as anode material with improved pseudocapacitive contribution and enhanced conductivity for lithium-ion batteries, Chemelectrochem 6 (2018) 690-699.
[39] Y. Luo, R. Guo, T. Li, F. Li, L. Meng, Z. Yang, Y. Wan, H. Luo, Conductive polypyrrole coated hollow

{NiCO}_{2} O_{4}

Microspheres as anode material with improved pseudocapacitive contribution and enhanced conductivity for lithium-ion batteries, Chemelectrochem 6 (2018) 690-699.
[40] S. Hao, B. Zhang, S. Ball, M. Copley, Z. Xu, M. Srinivasan, K. Zhou, S. Mhaisalkar, Y. Huang, Synthesis of multimodal porous

{ZnCo}_{2} O_{4}

and its electrochemical properties as an anode material for lithium ion batteries, J. Power Sources 294 (2015) 112-119.
[40] S. Hao, B. Zhang, S. Ball, M. Copley, Z. Xu, M. Srinivasan, K. Zhou, S. Mhaisalkar, Y. Huang, Synthesis of multimodal porous

{ZnCo}_{2} O_{4}

and its electrochemical properties as anode material for lithium ion batteries, J. Power Sources 294 (2015) 112-119.
[41] F. Wu, S. Zhang, B. Xi, Z. Feng, D. Sun, X. Ma, J. Zhang, J. Feng, S. Xiong, Unusual Formation of CoO@C “dandelions” derived from 2D kagóme MOLs for efficient lithium storage, Adv. Energy Mater. 8 (2018).
[41] F. Wu, S. Zhang, B. Xi, Z. Feng, D. Sun, X. Ma, J. Zhang, J. Feng, S. Xiong, Unusual Formation of CoO@C "dandelions" derived from 2D kagóme MOLs for efficient lithium storage, Adv. Energy Mater.8 (2018).
[42] H. Tabassum, R. Zou, A. Mahmood, Z. Liang, Q. Wang, H. Zhang, S. Gao, C. Qu, W. Guo, S. Guo, A universal strategy for hollow metal oxide nanoparticles encapsulated into B/N Co-doped graphitic nanotubes as high-performance lithiumion battery anodes, Adv. Mater. 30 (2018).
[42] H. Tabassum, R. Zou, A. Mahmood, Z. Liang, Q. Wang, H. Zhang, S. Gao, C. Qu, W. Guo, S. Guo, A universal strategy for hollow metal oxide nanoparticles encapsulated into B/N Co-doped graphitic nanotubes as high-performance lithiumion battery anodes, Adv. Mater.30 (2018).
[43] J. Liu, Y. Yuan, X. Guo, B. Li, R. Shahbazian-Yassar, D.H. Liu, Z. Chen, K. Amine, J. Lu, L. Yang, Z. Bai, Mesocrystallizing nanograins for enhanced

{Li}^{+}

storage, Adv. Energy Mater. (2021), 2100503.
[43] J. Liu, Y. Yuan, X. Guo, B. Li, R. Shahbazian-Yassar, D.H. Liu, Z. Chen, K. Amine, J. Lu, L. Yang, Z. Bai, Mesocrystallizing nanograins for enhanced

{Li}^{+}

storage, Adv. Energy Mater.(2021), 2100503.
[44] L. Wang, A. Menakath, F. Han, Y. Wang, P.Y. Zavalij, K.J. Gaskell, O. Borodin, D. Iuga, S.P. Brown, C. Wang, K. Xu, B.W. Eichhorn, Identifying the components of the solid-electrolyte interphase in Li-ion batteries, Nat. Chem. 11 (2019) 789-796.
[44] L. Wang, A. Menakath, F. Han, Y. Wang, P.Y. Zavalij, K.J. Gaskell, O. Borodin, D. Iuga, S.P. Brown, C. Wang, K. Xu, B.W. Eichhorn, Identifying the components of the solid-electrolyte interphase in Li-ion batteries, Nat.Chem.11 (2019) 789-796.
[45] X. Cao, X. Ren, L. Zou, M.H. Engelhard, W. Huang, H. Wang, B.E. Matthews, H. Lee, C. Niu, B.W. Arey, Y. Cui, C. Wang, J. Xiao, J. Liu, W. Xu, J.-G. Zhang, Monolithic solid-electrolyte interphases formed in fluorinated orthoformate-based electrolytes minimize Li depletion and pulverization, Nat. Energy 4 (2019) 796-805.
[45] X. Cao，X. Ren，L. Zou，M.H. Engelhard，W. Huang，H. Wang，B.E. Matthews，H. Lee，C. Niu，B.W. Arey，Y. Cui，C. Wang，J. Xiao，J. Liu，W. Xu，J.-G. Zhang，Monolithic solid-electrolyte interphases formed in fluorinated orthoformate-based electrolytes minimize Li depletion and pulverization，Nat.Zhang，在含氟原甲酸酯基电解质中形成的单片固体电解质相间层可最大限度地减少锂损耗和粉化，Nat.Energy 4 (2019) 796-805.
[46] C. Ding, W. Xu, M. Wang, X. Zeng, W. Wang, Microstructure controlled

{ZnCo}_{2} O_{4} / C

microhydrangea nanocomposites as highly reliable anodes for lithium-ion batteries, Int. J. Energy Res. 44 (2019) 977-987.
[46] C. Ding, W. Xu, M. Wang, X. Zeng, W. Wang, Microstructure controlled

{ZnCo}_{2} O_{4} / C

microhydrangea nanocomposites as highly reliable anodes for lithium-ion batteries, Int.44 (2019) 977-987.
[47] W. Chen, T. Lei, T. Qian, W. Lv, W. He, C. Wu, X. Liu, J. Liu, B. Chen, C. Yan, J. Xiong, A new hydrophilic binder enabling strongly anchoring polysulfides for high-performance sulfur electrodes in lithium-sulfur battery, Adv. Energy Mater. 8 (2018), 1702889 .
[47] W. Chen、T. Lei、T. Qian、W. Lv、W. He、C. Wu、X. Liu、J. Liu、B. Chen、C. Yan、J. Xiong, A new hydrophilic binder enabling strongly anchoring polysulfides for high-performance sulfur electrodes in lithium-sulfur battery, Adv. Energy Mater.8 (2018), 1702889 .

- Corresponding author. College of Biomass Science and Engineering, Sichuan University, Chengdu, 610065, China.
  通讯作者：四川大学生物质科学与工程学院四川大学生物质科学与工程学院，成都，610065
E-mail address: ronghuiguo214@126.com (R. Guo).
电子邮件地址：ronghuiguo214@126.com (R. Guo)。

A R TICLE IN F O文章

Keywords: 关键词：

Abstract 摘要

1. Introduction 1.导言

2. Experimentals 2.试验品

2.1. Preparation of metal ion Zn 2 + Zn 2 + Zn^(2+)\mathrm{Zn}^{2+} @Co 2 + 2 + ^(2+){ }^{2+} @PAN@nanofibers2.1.制备金属离子 Zn 2 + Zn 2 + Zn^(2+)\mathrm{Zn}^{2+} @Co 2 + 2 + ^(2+){ }^{2+} @PAN@ 纳米纤维

2.2. Synthesis of ZnCo 2 O 4 ZnCo 2 O 4 ZnCo_(2)O_(4)\mathrm{ZnCo}_{2} \mathrm{O}_{4} @carbon nanofiber composite2.2. ZnCo 2 O 4 ZnCo 2 O 4 ZnCo_(2)O_(4)\mathrm{ZnCo}_{2} \mathrm{O}_{4} @碳纳米纤维复合材料的合成

2.3. Characterization 2.3.特征描述

2.4. Electrochemical measurement2.4.电化学测量

3. Results and discussion3.结果和讨论

4. Conclusion 4.结论

Declaration of competing interest利益冲突声明

Acknowledgment 鸣谢

Appendix A. Supplementary data附录 A.补充数据

References 参考资料

A R TICLE IN F O
文章

2.1. Preparation of metal ion ${Zn}^{2 +}$ @Co $^{2 +}$ @PAN@nanofibers
2.1.制备金属离子 ${Zn}^{2 +}$ @Co $^{2 +}$ @PAN@ 纳米纤维

2.2. Synthesis of ${ZnCo}_{2} O_{4}$ @carbon nanofiber composite
2.2. ${ZnCo}_{2} O_{4}$ @碳纳米纤维复合材料的合成

2.4. Electrochemical measurement
2.4.电化学测量

3. Results and discussion
3.结果和讨论

Declaration of competing interest
利益冲突声明

Appendix A. Supplementary data
附录 A.补充数据