Hierarchically designed NiCo2O4 nanowire/NiCo2O4 nanosheet electrodes for high-performance energy storage applications

Abstract

A NiCo2O4 nanowire/NiCo2O4 nanosheet composite with a nanostructure was fabricated on nickel foam for use in high-performance supercapacitors by using two-step solution-based approaches such as hydrothermal and chemical bath deposition methods. In this study, the supercapacitive performance of NiCo2O4 nanowires was compared with that of NiCo2O4 nanowire/NiCo2O4 nanosheet arrays in a 2 M KOH electrolyte. The electrochemical study shows that NiCo2O4 nanowires/NiCo2O4 nanosheets exhibit higher electrochemical performance than NiCo2O4 nanowires. The NiCo2O4 nanowires/NiCo2O4 nanosheets (1866 F/g) have a high specific capacitance than NiCo2O4 nanowires (1023 F/g), at 2 A/g. Further, NiCo2O4 nanowire/NiCo2O4 nanosheet arrays show high electrochemical cycling stability of 94.8% over 5,000 cycles. This enhanced electrochemical performance is attributed to the hierarchically arranged morphology of the NiCo2O4 nanowire/NiCo2O4 nanosheet composite, which provides a large number of active sites for redox reactions, and fast ion-transfer ability.