Rationally Designed Heterostructure ZnS/SnS@N-Doped Carbon Microspheres as High-Performance Anode for Lithium-Ion Batteries

Abstract

Metal sulfides are considered promising anodes for lithium-ion batteries (LIBs) because of its high capacity. Among all metal sulfides, Tin(II) sulfide (SnS), possessing a unique 2D structure and with high lithium storage capacity, attracted more attention as a promising anode for LIBs. However, the serious volume change, sluggish kinetics, and unsatisfied electric conductivity during the charging/discharging process, which lead to poor rate capability and fast capacity fading. Herein, a ZnS/SnS@C yolk-shell microspheres (ZSS@NC) is synthesized through a facile hydrothermal process coupled with a PPy coating and sulfidation-in-microsphere strategy. The built-in electric field generated from ZnS/SnS heterostructure benefits the rapid transport of Li-ion and the improvement of electric conductivity. Meanwhile, the N-doped carbon further improves the electronic conductivity and provides a robust support architecture, which can mitigate the volume variation of ZnS/SnS. Therefore, the ZnS/SnS@NC delivers high capacity (775.5 mAh g^-1 at 200 mA g^-1 after 200 cycles), outstanding rate performance (395.8 mAh g^-1 at 5 A g^-1), and superior long-term cycling performance (571.2 mAh g^-1 at 1 A g^-1 after 1000 cycles).

Keywords: Lithium-ion battery, anode material, bimetallic sulfides, heterostructure, N-doped carbon