Reduced graphene oxide-wrapped ZnS–SnS2 heterojunction bimetallic hollow cubic boxes as high-magnification and long lifespan supercapacitor anode materials

Abstract

Metal sulfides have attracted extensive attention due to their excellent electrochemical performance. However, issues such as poor conductivity and severe volume expansion during charge and discharge processes affect the applications of sulfides as electrode materials. Here, a combination of coprecipitation and high-temperature sulfidation methods are employed to synthesize a ZnS–SnS₂ composite with a hollow cubic structure, which is further composited with reduced graphene oxide (RGO) to form ZnS–SnS₂ hollow cubic boxes encapsulated in a conductive framework of reduced graphene oxide (RGO) (denoted as ZnS–SnS₂@RGO) for electrode materials. The hollow structure effectively alleviates the pulverization of ZnS–SnS₂@RGO caused by volume expansion during charge and discharge processes. The heterogeneous structure formed by ZnS and SnS₂ effectively reduces the electron transfer resistance of the material. The use of RGO wrapping enhances the conductivity of the ZnS–SnS₂ hollow cubic boxes, and RGO's dispersion effect on the ZnS–SnS₂ cubes improves particle agglomeration, further mitigating volume expansion of the material. These results indicate the outstanding electrochemical performance of heterostructural ZnS–SnS₂ hollow cubic electrodes encapsulated with reduced graphene oxide as a conductive framework. The fabrication process provides a novel approach for addressing volume expansion and poor conductivity issues in other pseudocapacitive materials.