Self-Sacrificing Template-Derived Hollow-Structured NiCo2S4 Spheres with Highly Efficient Supercapacitance Performance

Highly efficient supercapacitance performance requires electrode materials to have large electrochemical reaction interfaces due to the surface reaction properties. In this work, a hollow-structured NiCo2S4 spinel is synthesized via an in situ preparation strategy. First, NiCo-glycolate solid spheres are obtained via a simple solvothermal method. The hollow structure is formed through a liquid sulfidation approach using NiCo-glycolate solid spheres as a self-sacrificing template, according to the Kirkendall effect. NiCo2S4 with hollow-structured spheres as supercapacitor electrodes exhibits an excellent specific capacitance of 1387.5 F.g(-1) at 1 A.g(-1) and a highly efficient cycling stability for over 4500 cycles. Moreover, when served as an all-solid-state asymmetric supercapacitor electrode, superior energy density (39 Wh.kg(-1)) is achieved at the power density of 215 W.kg(-1). The superior energy storage performance is ascribed to the unique properties of the NiCo2S4 spinel, the mesoporous structure, and the large hollow space for alleviating the structure strain.