Synthesis of CoS@rGO composites with excellent electrochemical performance for supercapacitors

The transition metal oxides/sulfides which are pseudocapacitor electrode materials have been extensively investigated and demonstrated brilliant electrochemical performances. In this study, we have successfully prepared hierarchical structure cobalt sulfide/graphene composite (CoS@rGO). The complete fabrication process as follows: the cobalt sulfide nanosheets have been prepared by an ultrasound-assisted soaking method using cobalt hydroxide nanosheets as precursor, then the cobalt sulfide/graphene composite(CoS@rGO) was prepared by hydrothermal mothed. The hierarchical structure electrode materials can make full use of both components and exhibits a potential synergistic effect. As electrode material for supercapacitor, the CoS@rGO composite are characterized by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements. Owing to the unique hierarchical structure, the CoS@rGO composite exhibits excellent electrochemical performances, including high specific capacitance and remarkable cycling stability (90.5% retaining after 3000 cycling). All these results indicate that the CoS@rGO composite is promising for potential application in supercapacitors. In addition, such a novel and facile route to synthesis the high-performance CoS@rGO composite may open a new pathway to prepare sulfide materials with outstanding electrochemical performance.