Electrochemical Properties of NiCo2S4/rGO Nanocomposites Synthesized by Hydrothermal Method

Abstract

Background: Transition metal sulfide, especially Nickel cobalt sulfide (NiCo2S4), has been widely studied as electrode material based on its excellent electrochemical properties. It is found that increasing the conductivity and stability of the electrode material can greatly improve the performance of the supercapacitor. Method: Three-dimensional (3D) NiCo2S4 and NiCo2S4/rGO composite material are synthesized via two-step hydrothermal method for high-performance supercapacitor electrode material. Besides, the electrochemical properties of NiCo2S4/rGO have been analyzed by many characterization methods. Results: The experiment shows that pure NiCo2S4 samples exhibit a cubic spinel structure, and their morphologies are 3D flower-like structures. The ultra-pasteurized NiCo2S4 nanospheres have been successfully inserted into the surface of graphene through a hydrothermal method. A large specific surface of NiCo2S4/rGO has been observed from morphology and structure analysis. The specific electric capacity of the NiCo2S4/rGO electrode has reached 1002.9 F/g, when the current density is 1 A/g. Conclusion: It has been found that the capacitance retention rate of NiCo2S4/rGO composite electrode material has increased from 59.6% to 88.5% compared to NiCo2S4 after 2000 cycles at 5 A/g. Moreover, experiments denote that NiCo2S4/rGO electrode material has a larger ion diffusion rate and lesser solution resistance from the Electrochemical Independence Spectrum (EIS).