Nano Sn2 S3 Embedded in Nitrogenous-Carbon Compounds for Long-Life and High-Rate Cycling Sodium-Ion Batteries.

Abstract

Metallic tin (Sn) compounds are viewed as promising candidates for sodium-ion batteries (SIB) anode materials yet suffer from large volume expansion and limited electrode kinetics. Manufacturing rational structure is a crucial factor to achieve high-efficiency sodium storage for SIBs. In this study, nano Sn2 S3 embedded in nitrogenous-carbon compounds (nano-Sn2 S3 /C) was designed for SIB anode materials via a facile three-step strategy: precipitation, heat treatment and vulcanization with no templating agent. Density functional theory calculations suggested that Sn2 S3 displayed a low Na+ diffusion energy barrier and the Sn-S bonds could be rebuilt during the sodiation/de-sodiation process. Notably, electrochemical measurements coupled with ex-situ X-ray diffraction and ex-situ transmission electron microscopy were proposed to reveal the underlying Na+ storage mechanisms. Sn2 S3 acted as a high-capacity composition, while the porous nitrogenous-carbon matrix served as a rigid-conductive frame to accommodate the volume expansion and prevented the aggregation of nano Sn2 S3 . The rationally generated architectures benefited greatly in rate capacity and structural stability. As expected, the as-prepared nano Sn2 S3 /C exhibited remarkable rate capabilities with a specific capacity of 603 and 160 mAh g-1 under typical conditions at 0.2 and 4 A g-1 , respectively. This work may trigger new enthusiasm for engineering high-performance SIB anode materials.