Ni/NiO nanoparticles loaded carbon sphere for high-performance supercapacitor

In this work, carbon sphere (CS), NiO, and Ni/NiO/CS composite were successfully synthesized by hydrothermal and calcination methods. The structure and morphology characterization suggested the loading of Ni/NiO nanoparticles on CS. Glucose and poly (styrene-p-sodium) sulfonate (PSS) were used as a carbon source and template, respectively. N2 adsorption–desorption isotherms and Barrett-Joyner Halenda (BJH) pore size/distribution suggested the improvement of specific surface area and porosity by making composite, respectively. The electrode materials were used for supercapacitors and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge (GCD). According to electrochemical surface area (ECSA) analysis, three-fold enhancement of double-layer capacitance (Cdl) was observed in composite as compared to NiO. The composite exhibited excellent specific capacitance of 550 F/g at a current density of 1 A/g. It is attributed to the synergetic effect of Ni/NiO and carbon and excellent surface area/porosity. The composite revealed excellent cyclic stability with a capacity retention of 96 % after 2000 cycles at 10 A/g. These results suggest that the Ni/NiO nanoparticle-loaded carbon sphere is a promising electrode material for high-performance supercapacitors.