Dandelion‐like Nanospheres Synthesized by CoO@CuO Nanowire Arrays for High‐Performance Asymmetric Supercapacitors

Abstract

Recently, three-dimensional-structure materials have attracted enormous attention in energy-storage fields on account of their excellent electrochemical performance. In this study, hierarchical nanospheres consisting of mesoporous CoO@CuO nanowires on a three-dimensional conductive Ni foam are prepared by a one-step hydrothermal method combined with a subsequent annealing process. Compared to CoO or CuO alone, the as-obtained CoO@CuO/Ni hybrid nanowires show good electronic conductivity owning to the abundant existence of O vacancies in them. In a three-electrode system, the area capacitance of the prepared CoO@CuO/Ni electrode reaches 2.94 F cm À 2 (1.32 C cm À 2 ) at 1 mA cm À 2 , and the CoO@CuO/Ni electrode presents an outstanding cycle performance. Moreover, a CoO@CuO/Ni//AC ASC asymmetric supercapacitor is fabricated and found to display a high energy density of 20.22 Wh kg À 1 at 800 W kg À 1 . Hence, this novel CoO@CuO/Ni hybrid nanowires with excellent electrochemical properties shows outstanding potential in the practical application of high-energy storage devices.