Synthesis of reduced graphene oxide wrapped-copper sulfide hollow spheres as electrode material for supercapacitor

Copper sulfide (CuS) is a promising candidate for the electrode material in supercapacitor due to its metal-like electronic conductivity and high theoretical capacity. However, volume change during cycling causes poor cycling stability and improving cycle life is a major research challenge. Herein, we present a strategy by fabricating reduced graphene oxide (rGO)-wrapped CuS hollow spheres using a simple solvothermal route assisted by ethylene glycol to improve the electrochemical performance of CuS in supercapacitors. The as-prepared samples are well characterized by utilizing Scan electron microscope, Transmission electron microscope, powder X-ray diffraction, X-ray photoelectron spectrum and Raman spectra techniques. It is demonstrated that the obtained CuS/rGO composite shows excellent electrochemical performance as electrode material for supercapacitors. The CuS/rGO electrode displays a significantly enhanced specific capacitance of 2317.8 F g−1 and an excellent cycling stability of 96.2% retention after 1200 cycles at a current density of 1.0 A g−1. The likely cause is the synergetic effects between the hollow spherical structure and the high conductivity of rGO. More importantly, the present synthesis strategy may be readily extended to the preparation of other composites based on CuS with tailored morphologies and surface textures for potential applications in energy storage and conversion devices.