A sol-gel process for the synthesis of NiCo2O4 having improved specific capacitance and cycle stability for electrochemical capacitors

Abstract

High performance nickel cobaltite (NiCo2O4) with ultrahigh capacitance is synthesized by a facile sol-gel process and then calcined at 300◦C. The structure and morphology is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and nitrogen adsorption/desorption experiments.Amesoporous structure with high specific surface area is obtained. Electrochemical properties are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS). The NiCo2O4 exhibits excellent electrochemical performance. The highest specific capacitance of 1128 F g−1 is achieved at a current density of 5 mA cm−2 and 92.5% of the initial specific capacitance remained after 1000 cycles. NiCo2O4 prepared by this scale-able route could be a promising electrode material for electrochemical capacitors.