Ni ion doping effects on Sb2S3 and SnS for anode materials of sodium ion batteries

Abstract

Sodium-ion batteries (SIBs) have attracted growing attention as cost-effective and resource-abundant alternatives to lithium-ion batteries (LIBs). Among potential anode candidates, sulfide-based materials such as Sb2S3 and SnS offer high theoretical capacities but suffer from low Initial coulombic efficiency (ICE) and rapid capacity fading during cycling. In this work, we systematically investigate the effect of nickel (Ni) doping on Sb2S3 and SnS anodes. The materials are synthesized by a hydrothermal method, and their structural, morphological, and electrochemical properties are characterized using X-ray diffraction (XRD), Scanning electron microscopy (SEM), and galvanostatic cycling tests. Ni doping induces notable changes in the crystal structure and morphology of both Sb2S3 and SnS, leading to improved electrochemical performance. Specifically, Sb2S3 with 5 at% Ni doping exhibits a stable capacity of similar to 600 mAh<middle dot>g(-1) after 50 cycles at 0.2 A g(-1), whereas the undoped sample shows similar to 30 % capacity loss (similar to 400 mAh<middle dot>g(-1)). In SnS, the optimal doping concentration is 7 at%, delivering 322 mAh<middle dot>g(-1) after 50 cycles at 0.2 A g(-1), while higher doping contents result in performance degradation. These results demonstrate that appropriate Ni doping enhances the cycling stability and alleviates the limitation of low ICE in sulfide-based anode materials for SIBs.