Controllable construction of yolk–shell Sn–Co@void@C and its advantages in Na-ion storage

作     者：Shuang Liu Xin-Ze Li Bin Huang Jian-Wen Yang Quan-Qi Chen Yan-Wei Li Shun-Hua Xiao Shuang Liu;Xin-Ze Li;Bin Huang;Jian-Wen Yang;Quan-Qi Chen;Yan-Wei Li;Shun-Hua Xiao

作者机构：Guangxi Key Laboratory of Electrochemical and Magneto-Chemical Functional MaterialsCollege of Chemistry and BioengineeringGuilin University of TechnologyGuilin 541004China 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2021年第40卷第9期

页      面：2392-2401页

核心收录：

学科分类：0808[工学-电气工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 

基　　金：financially supported by the National Natural Science Foundation of China(No.51804089) Guangxi Natural Science Foundation(Nos.2017GXNSFBA198141 and 2017GXNSFAA198230) the Foundation of Guilin University of Technology(No.GLUTQD2017005) 

主　　题：Nanocomposites Yolk-shell structure Tin-based alloys Anodes Sodium-ion batteries 

摘      要：In the family of anodes for sodium-ion batteries,alloy-type anodes possess higher theoretical specific capacity than carbon anodes. The theoretical specific capacity of metallic Sn is 847 mAh·g^(-1). However, the tinbased material undergoes a large volume expansion during the sodium-ion intercalation process, which leads to the crack and pulverization of the electrode, consequently resulting in a significant capacity loss. In this paper, a yolk–shell-structured Sn–Co@void@C composite composed of a Sn–Co alloy core, a carbon shell and void space between the core and shell is designed and *** with the carbon-encapsulated SnCo without void space(Sn–Co@C) and carbon-encapsulated pure Sn core shell with void space(Sn@void@C), this composite exhibits improved reversibility, cyclic performance and rate capability. This work highlights the important roles of Co in the alloy and the void space between the core and the shell. The former can not only buffer the volume expansion of Sn, but also act as an electrical conductor. The void space can further tolerate the volume expansion of the Sn–Co core. Owing to this unique microstructure, the Sn–Co@void@C composite shows an initial reversible capacity of 591.4 mAh·g^(-1), at a current density of50 mA·g^(-1). After 100 charge/discharge cycles at100 mA·g^(-1), the composite still delivers 330 mAh·g^(-1).