POWER 权力

Construction of ${Ti}_{3} C_{2}$ MXene@C@SnS with layered rock stratum structure for high-performance lithium storage
构建具有层状岩层结构的 ${Ti}_{3} C_{2}$ MXene@C@SnS，实现高性能锂存储

Hong Tang $^{a}$ , Ronghui Guo $^{a,^{*}}$ , Mengjin Jiang $^{b}$ , Yue Zhang $^{a}$ , Xiaoxu Lai $^{a}$ , Ce Cui $^{a}$ ,
Hong Tang $^{a}$ , Ronghui Guo $^{a,^{*}}$ , Mengjin Jiang $^{b}$ , Yue Zhang $^{a}$ , Xiaoxu Lai $^{a}$ , Ce Cui $^{a}$ 、Hongyan Xiao $^{a}$ , Shouxiang Jiang $^{c}$ , Erhui Ren $^{a}$ , Qin Qin $^{a}$
肖红艳 $^{a}$ , 蒋守祥 $^{c}$ , 任尔辉 $^{a}$ , 秦琴 $^{a}$ $^{a}$ 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 $^{b}$ College of Polymer Science & Engineering and State Kjieey Lab Polymer Material & Engineering, Sichuan University, Chengdu, 610065, China
$^{b}$ 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 $^{c}$ Institute of Textiles and Clothing, The Hong Kong Polytechnic University, China
$^{c}$ 中国香港理工大学纺织及制衣研究所

H I G H L I G H T S

${Ti}_{3} C_{2}$ MXene@C@SnS hybrids with layered rock stratum structure was successfully prepared.
<成功制备了具有层状岩层结构的 MXene@C@SnS 混合物。
${Ti}_{3} C_{2}$ MXene@C@SnS hybrids have large surface area ( $255.78 m^{2} g^{- 1}$ ) and porosity.
${Ti}_{3} C_{2}$ MXene@C@SnS杂化物具有较大的表面积（ $255.78 m^{2} g^{- 1}$ ）和孔隙率。
The electrode has high reversible capacity of $1473 mA h g^{- 1}$ at $0.1 A g^{- 1}$ .
该电极在 $0.1 A g^{- 1}$ 时具有 $1473 mA h g^{- 1}$ 的高可逆容量。
The electrode has excellent rate performance of $640 mA h g^{- 1}$ at $5 A g^{- 1}$ .
该电极在 $5 A g^{- 1}$ 时具有 $640 mA h g^{- 1}$ 的优异速率性能。
Outstanding cycle stability of 1050 mA $h g^{- 1}$ over 350 cycles at $1 A g^{- 1}$ .
在 $1 A g^{- 1}$ 的 350 个周期内， $h g^{- 1}$ 达到 1050 mA 的出色周期稳定性。

A R T I C L E I N F O

Keywords: 关键词：

Lithium-ion storage 锂离子存储

{Ti}_{3} C_{2}

MXene@C@SnS hybrids

{Ti}_{3} C_{2}

MXene@C@SnS杂化物
Layered rock stratum structure
层状岩层结构
Rate performance 费率性能
Long-cycle stability 长周期稳定性
GR A P H I C A L A B S T R A C T
训研所

A B S T R A C T

Tin sulfide ( SnS ) possesses high theoretical capacity and make it a very potential anode material for lithium-ion batteries. Nevertheless, the poor electrical conductivity of SnS is prone to collapse during lithiation/de-lithiation. Herein,

{Ti}_{3} C_{2}

MXene@C@SnS hybrids with layered rock stratum structure are prepared as an anode electrode for lithium ion batteries through hydrothermal and subsequent annealing. The hybrids integrate large specific surface area and porosity, and accelerate electron/ion transfer. The

{Ti}_{3} C_{2}

MXene@C@SnS anode exhibits a superior capacity (

1473 mA g^{- 1}

0.1 {Ag}^{- 1}

), outstanding rate capability (

640 mA g^{- 1}

5 A g^{- 1}

and keeps

1142.2 mA g g^{- 1}

for 70 cycles returning to

0.5 A g^{- 1}

again) and excellent long-cycle stability (

1050 mA h g^{- 1}

1 A g^{- 1}

over 350 cycles). Kinetic analysis reveals that the excellent rate capability is controlled by surface pseudocapacitance behavior at high current. This result indicates that

{Ti}_{3} C_{2}

MXene@C@SnS can be potentially applied in the field of lithium storage.
硫化锡（SnS）具有很高的理论容量，是一种非常有潜力的锂离子电池负极材料。然而，SnS 的导电性较差，在锂化/去锂化时容易发生塌陷。在此，我们通过水热法和随后的退火法制备了具有层状岩层结构的

{Ti}_{3} C_{2}

MXene@C@SnS杂化物，作为锂离子电池的负极电极。该杂化物具有较大的比表面积和孔隙率，可加速电子/离子传输。

{Ti}_{3} C_{2}

MXene@C@SnS阳极表现出卓越的容量（

0.1 {Ag}^{- 1}

时为

1473 mA g^{- 1}

）、出色的速率能力（

5 A g^{- 1}

时为

640 mA g^{- 1}

并保持

1142.2 mA g g^{- 1}

70次循环后再次回到

0.5 A g^{- 1}

）和出色的长循环稳定性（

1 A g^{- 1}

时为

1050 mA h g^{- 1}

超过350次循环）。动力学分析表明，卓越的速率能力是由大电流时的表面假电容行为控制的。这一结果表明，

{Ti}_{3} C_{2}

MXene@C@SnS 有可能应用于锂存储领域。

1. Introduction 1.导言

Lithium-ion batteries (LIBs) are a very important type of rechargeable batteries due to their high energy density, long lifetime, no memory effect, good safety and environmental benignity, so it has been widely used in various portable electronic devices, new energy electric vehicles and power-grid systems

[1 - 4]

. However, LIBs are meeting with urgently need on energy density increase, long cycle longevity and low cost when
锂离子电池（LIB）是一种非常重要的可充电电池，由于其能量密度高、寿命长、无记忆效应、安全性好且对环境无害，已被广泛应用于各种便携式电子设备、新能源电动汽车和电网系统

[1 - 4]

。然而，锂离子电池在提高能量密度、长周期寿命和低成本方面的需求十分迫切。

https://doi.org/10.1016/j.jpowsour.2020.228152
Received 9 January 2020; Received in revised form 28 March 2020; Accepted 2 April 2020
Available online 20 April 2020
0378-7753/© 2020 Elsevier B.V. All rights reserved.
they are further applied in the field of electric vehicles and power-grid systems [5-7]. The electrochemical performance of LIBs usually depends on anode materials, but the commercial graphite anode only has a

from meeting the ever-growing demand of energy. Therefore, exploring lithium storage anode materials with high capacity becomes increasingly urgency.
能源需求不断增长。因此，探索高容量锂储能正极材料变得日益迫切。

Among various anode materials, SnS as transition metal sulfide, are very promising as a replacement for lithium-ion battery anodes because of its high theoretical capacity (

1368 mA h^{- 1}

) provided by the unique alloying conversion during charge and discharge. Nevertheless, SnS suffers from inferior capacity and rate performance because of intrinsic poor electrical conductivity and structural instability. In addition, the SnS lattice collapse easily during large-scale lithiation/de-lithiation, resulting in fast capacity decay and inferior rate performance [10].
在各种负极材料中，作为过渡金属硫化物的 SnS 很有希望成为锂离子电池负极的替代材料，因为它在充放电过程中通过独特的合金转换提供了很高的理论容量（

1368 mA h^{- 1}

）。然而，SnS 因其固有的低导电性和结构不稳定性，在容量和速率性能方面都较差。此外，在大规模锂化/去锂化时，SnS 晶格容易坍塌，导致容量快速衰减和速率性能降低 [10]。

To overcome the above obstacles, construction of nanostructured SnS composites has been proven to significantly improve electrochemical performance. Especially, SnS nanoparticles can provide a large number of active sites due to their high specific surface area. The SnS nanoparticles can effectively shorten the lithium ion diffusion distance and increase the specific surface area to enlarge the active sites of lithium ion insertion and extraction [11,12]. In addition, anchoring SnS nanoparticles on conductive matrices was an effective strategies to improve intrinsic electrical conductivity and prevent SnS nanoparticles from aggregating. Currently, SnS nanoparticles have been anchored on various conductive matrices such as graphene [10] and carbon nanosheet [13], which greatly improves capacity of SnS nanoparticle and cycle stability. However, graphene and carbon nanosheets exhibits slow lithium ion diffusion and depressed reaction dynamics when being used as anode materials for lithium-ion batteries [14]. Compared with graphene and carbon nanosheets, the two-dimensional (2D)

{Ti}_{3} C_{2}

MXene has high diffusion mobility and low diffusion energy barrier of lithium ions [15]. The

{Ti}_{3} C_{2}

MXene has fast electron transfer rate toward accelerating reaction dynamics. Therefore,

{Ti}_{3} C_{2}

MXene can be used as an alternative conductive matrice for growth of SnS nanoparticles for lithium ion storage. Recently,

SnS / PDDA - {Ti}_{3} C_{2}

composite was prepared by electrostatic attraction, which showed lithium ion storage capacity of

795 mA h g^{- 1}

50 mA g^{- 1}

. However, SnS/PDDA-Ti

_{3} C_{2}

composite did not show the superiority of SnS with high capacity (

1368 mA h g^{- 1}

) [16]. Additionally,

{Ti}_{3} C_{2}

MXene tends to be automatically converted to stable metal oxides, which results in reduction of the electrical conductivity and diffusion mobility of lithium ions. Previous studies have proven that carbon encapsulation could efficiently alleviate the oxidation of MXene [17]. However, carbon-encapsulated SnS nanoparticles anchored on multilayer

{Ti}_{3} C_{2}

MXene by in-situ growth as anode electrode material for LIBs with high-performance lithium storage have not been reported.
为克服上述障碍，纳米结构 SnS 复合材料的构建已被证明可显著提高电化学性能。尤其是 SnS 纳米粒子的高比表面积可以提供大量的活性位点。SnS 纳米颗粒能有效缩短锂离子扩散距离，增加比表面积，从而扩大锂离子插入和萃取的活性位点 [11,12]。此外，将 SnS 纳米粒子锚定在导电基质上也是提高其内在导电性和防止 SnS 纳米粒子聚集的有效策略。目前，已有人将 SnS 纳米粒子锚定在石墨烯[10]和碳纳米片[13]等多种导电基质上，从而大大提高了 SnS 纳米粒子的容量和循环稳定性。然而，石墨烯和碳纳米片在用作锂离子电池的负极材料时，锂离子扩散速度较慢，反应动力学受抑制[14]。与石墨烯和碳纳米片相比，二维（2D）

{Ti}_{3} C_{2}

MXene 具有较高的扩散迁移率和较低的锂离子扩散能垒[15]。

{Ti}_{3} C_{2}

MXene 具有快速的电子转移率，可加速反应动力学。因此，

{Ti}_{3} C_{2}

MXene 可用作生长 SnS 纳米粒子的替代导电材料，用于锂离子存储。最近，利用静电吸引法制备了

SnS / PDDA - {Ti}_{3} C_{2}

复合材料，在

50 mA g^{- 1}

条件下显示出

795 mA h g^{- 1}

的锂离子存储容量。然而，SnS/PDDA-Ti

_{3} C_{2}

复合材料并没有显示出 SnS 高容量（

1368 mA h g^{- 1}

）的优越性[16]。此外，

{Ti}_{3} C_{2}

MXene 往往会自动转化为稳定的金属氧化物，从而导致锂离子的导电性和扩散迁移率降低。以往的研究证明，碳包覆可以有效缓解 MXene 的氧化作用 [17]。然而，通过原位生长将碳包封的 SnS 纳米粒子锚定在多层

{Ti}_{3} C_{2}

MXene 上，作为具有高性能储锂功能的 LIB 的正极电极材料的研究还未见报道。

In this work, the

{Ti}_{3} C_{2}

MXene@C@SnS hybrids with layered rock stratum structure were synthesized by a novel annealing reduction strategy. In the presence of glucose, carbon encapsulation nanoparticleslike

{SnS}_{2}

was grown in situ on the surface and interlayer of multilayer

{Ti}_{3} C_{2}

MXene by hydrothermal treatment, and

{SnS}_{2}

was then reduced to SnS after annealing. The illustration of synthesis of MXene@C@SnS hybrids is shown in Fig. 1. The

{Ti}_{3} C_{2}

MXene@C@SnS hybrids possess large specific surface area to provide plentiful active sites for the electrochemical reaction and rich porous structure can provide numerous ion transport channels to significantly shorten the diffusion channel of electrolyte. The carbon nanolayers effectively improve electrical conductivity and structural stability. As a result,

{Ti}_{3} C_{2}

MXene@C@SnS electrode exhibits excellent lithium storage performance when being employed as lithium-ion battery anode. The electrode delivers a remarkable reversible capacity of

1473 mA h^{- 1}

0.1 {Ag}^{- 1}

, especially outstanding rate capability of

640 mA h^{- 1}

at a high current density of

5 A g^{- 1}

and maintaining a capacity of

1142.2 mA h^{- 1}

for 70 cycles returning to

0.5 A g^{- 1}

again. The electrode still delivers a reversible capacity up to

1050 mA h g^{- 1}

with

99 %

Coulombic efficiency for 350 cycles at a high current density of

1 A g^{- 1}

.
本研究采用新型退火还原策略合成了具有层状岩层结构的

{Ti}_{3} C_{2}

MXene@C@SnS杂化物。在葡萄糖存在的条件下，通过水热处理在多层

{Ti}_{3} C_{2}

MXene的表面和层间原位生长出类似

{SnS}_{2}

的碳封装纳米颗粒，然后将

{SnS}_{2}

退火还原成SnS。MXene@C@SnS 混合物的合成示意图如图 1 所示。

{Ti}_{3} C_{2}

MXene@C@SnS杂化物具有较大的比表面积，为电化学反应提供了丰富的活性位点，丰富的多孔结构提供了众多的离子传输通道，大大缩短了电解质的扩散通道。碳纳米层可有效提高导电性和结构稳定性。因此，

{Ti}_{3} C_{2}

MXene@C@SnS 电极在用作锂离子电池负极时具有优异的储锂性能。该电极在

0.1 {Ag}^{- 1}

条件下具有

1473 mA h^{- 1}

的显著可逆容量，尤其是在

5 A g^{- 1}

的高电流密度条件下具有

640 mA h^{- 1}

的出色速率能力，并能在 70 个循环中保持

1142.2 mA h^{- 1}

的容量，再次回到

0.5 A g^{- 1}

。在

1 A g^{- 1}

的高电流密度下，该电极在 350 个循环中仍能提供高达

1050 mA h g^{- 1}

的可逆容量和

99 %

的库仑效率。

Construction of ${Ti}_{3} C_{2}$ MXene@C@SnS with layered rock stratum structure for high-performance lithium storage
构建具有层状岩层结构的 ${Ti}_{3} C_{2}$ MXene@C@SnS，实现高性能锂存储

H I G H L I G H T S

A R T I C L E I N F O

Keywords: 关键词：

A B S T R A C T

1. Introduction 1.导言

2. Experimental section 2.实验部分

2.1. Preparation of multilayer ${Ti}_{3} C_{2}$ MXene
2.1.制备多层 ${Ti}_{3} C_{2}$

Construction of Ti 3 C 2 Ti 3 C 2 Ti_(3)C_(2)\mathrm{Ti}_{3} \mathrm{C}_{2} MXene@C@SnS with layered rock stratum structure for high-performance lithium storage 构建具有层状岩层结构的 Ti 3 C 2 Ti 3 C 2 Ti_(3)C_(2)\mathrm{Ti}_{3} \mathrm{C}_{2} MXene@C@SnS，实现高性能锂存储

H I G H L I G H T S

A R T I C L E I N F O

Keywords: 关键词：

A B S T R A C T

1. Introduction 1.导言

2. Experimental section 2.实验部分

2.1. Preparation of multilayer Ti 3 C 2 Ti 3 C 2 Ti_(3)C_(2)\mathrm{Ti}_{3} \mathrm{C}_{2} MXene2.1.制备多层 Ti 3 C 2 Ti 3 C 2 Ti_(3)C_(2)\mathrm{Ti}_{3} \mathrm{C}_{2}

Construction of ${Ti}_{3} C_{2}$ MXene@C@SnS with layered rock stratum structure for high-performance lithium storage
构建具有层状岩层结构的 ${Ti}_{3} C_{2}$ MXene@C@SnS，实现高性能锂存储

2.1. Preparation of multilayer ${Ti}_{3} C_{2}$ MXene
2.1.制备多层 ${Ti}_{3} C_{2}$