Three dimensional flower-like CuO/Co3O4/r-GO heterostructure for high-performance asymmetric supercapacitors

Abstract

The supercapacitors have been widely used in the field of electronics appliances and automobiles, but its utility is limited by low energy density and poor specific capacitance. Energy density and specific capacitance of the supercapacitor is invariably determined by the electrode materials. Herein, a novel 3D flower-like CuO/Co3O4/r-GO heterostructure was synthesized by the hydrothermal method and used as an anode material for high-performance supercapacitors in an alkaline electrolyte solution. The as-prepared 3D flower-like CuO/Co3O4/r-GO heterostructure with high surface area provides vast interfacial contact area between electrode and electrolyte solution which offers a fast surface reaction kinetics and improved conductivity, thereby the remarkable electrochemical performance is achieved. The prepared CuO/Co3O4/r-GO heterostructure material shows an ultra-high specific capacitance of 1458 Fg-1 at a current density of 0.5 Ag-1, exceptional rate capability, and stable long- term cycling performance (97% retention after 10000 successive charge-discharge cycles at 5 Ag-1). In as-assembled asymmetric supercapacitor, CuO/Co3O4/r-GO heterostructure is an anode material and r-GO is a cathode material. The assembled device shows a high specific capacitance of 198 Fg-1 at 2 Ag-1, an ultra-high power density of 10510.30 W kg−1, and a high energy density of 34.20 Wh kg−1. Meanwhile, the ASC device exhibits excellent rate capability (97%) after 10000 successive charge-discharge cycles at 5 Ag-1 in the PVA-KOH gel electrolyte.