Effects of reductants on structures and electrochemical performances of Ni(OH)₂/reduced graphene oxide composites

In order to investigate the effects of reductants on structures and electrochemical performances of Ni(OH)₂/reduced graphene oxide (RGO) composites, Ni(OH)₂/RGO composites were synthesized using graphite oxide (GO) and nickel nitrate as precursors by hydrothermal method firstly. Then, the structures and morphologies of the composites were characterized using XRD, SEM and Raman spectrometer, and the electrochemical performances were investigated using cyclic voltammetry, galvanostatic charge-discharge curves and electrochemical impedance spectroscopy. The results show that when using (NH₂)₂CSO₂ as reductant, the synthesized β-Ni(OH)₂/RGO composite has mutually embedded structure of RGO nanosheets and Ni(OH)₂ nanosheets. The specific capacity of the β-Ni(OH)₂/RGO composite is 341.0 mAh/g in electrolyte (6 mol/L KOH solution) at discharge rate of 0.2C. The specific capacity of the composite is 242.2 mAh/g at discharge rate of 10.0C rate, which still maintains 83.8% of theoretical specific capacity for β-Ni(OH)₂. The conclusions obtained show that the synthesized Ni(OH)₂/RGO composites show excellent electrochemical performances.