Morphology and electrochemical properties of NiCo2S4 powders prepared by one-step solvothermal synthesis and their application as positive electrode for supercapacitor

Aim at developing electrode materials with prominent electrochemical performances for supercapacitor application, flower-like hierarchical nanostructure NiCo 2 S 4 powders (denoted as NCS-1) were synthesized by a facile one-step solvothermal method using the chelating agent of urea. The phase structure, particle morphology, specific surface area, and pore size distribution were examined, as well as the electrochemical properties of the electrodes prepared from the NiCo 2 S 4 powders. In order to tentatively explore the formation mechanism, NiCo 2 S 4 powders (denoted as NCS-2) were also prepared by the same method without urea. Meanwhile, the effect of urea on the structure and electrochemical performances was investigated. The results indicated that the chelating agent of urea played a significant role, coordinating with metal ions initially and releasing them slowly at elevating temperatures to form pure NiCo 2 S 4 compound. The NCS-1 electrodes exhibited a specific capacitance of 2339 F/g under a current density of 1 A/g and a capacitance retention of 56% after 5000 charge–discharge cycles measured at 20 A/g. The excellent electrochemical performances demonstrate that the flower-like NiCo 2 S 4 is a promising candidate for supercapacitor electrode.