Construction of Three-Dimensional Homogeneous NiCo₂O₄Core/Shell Nanostructure as High-Performance Electrodes for Supercapacitors

Abstract

A novel three-dimensional homogeneous NiCo2O4 core/shell nanowire arrays were first fabricated via a facile synthesis strategy on nickel foam as advanced binder-free electrodes. The structure and morphology of the as-synthesized samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectrometry (EDS) and transmission electron microscopy (TEM). This novel NiCo2O4/NiCo2O4 core/shell nanowire arrays exhibited superior electrochemical performances, including high specific capacitance of 2041 F g−1 at current density of 5 mA cm−2, excellent rate performance with a capacitance retention of 88% as the current density increases from 5 to 50 mA cm−2 and good long-term cyclic stability. These outstanding electrochemical characteristics are mainly attributed to the superstructure, which provides a large number of electroactive sites for redox reaction, shortens the ion diffusion paths and enhances the morphological stability in the electrochemical process.