Designed Synthesis and Electrochemical Performance Regulation of the Hierarchical Hollow Structure Cu 2 S/Cu 7 S 4 /NC Anode for Hybrid Supercapacitors.

Copper-based compounds have attracted increasing attention as electrode materials for rechargeable devices, but their poor conductivity and insufficient stability inhibit their further development. Herein, an effective method has been proposed to improve the electrochemical properties of the copper-based electrodes by coating carbon materials and generating unique micro/nanostructures. The prepared Cu2 S/Cu7 S4 /NC with hierarchical hollow structure possesses excellent electrochemical performance, attributing to the composition and structure optimization. The superior charge storage performance has been assessed by theoretical and experimental research. Specifically, the Cu2 S/Cu7 S4 /NC exhibits remarkably higher electrical conductivity and lower adsorption-free energy for O* and OH* than those of Cu2 O. Moreover, the Cu2 S/Cu7 S4 /NC delivers a high specific capacitance of 1261.3 F·g-1 at the current density of 1 A·g-1 and also has great rate performance at higher current densities, which are much better than those of the Cu2 O nanocubes. In addition, the assembled hybrid supercapacitor using Cu2 S/Cu7 S4 /NC as the anode exhibits great energy density, power density, and cycling stability. This study has proposed a novel and feasible method for the synthesis of high-performance copper-based electrodes and their electrochemical performance regulation, which is of great significance for the advancement of high-quality electrode materials and rechargeable devices.