Novel synthesis of copper sulfide plate-assembled hollow cages as electrocapacitive material of energy storage device

Copper sulfide with ease fabrication, low cost and high electrocapacitive behavior has been widely applied as electrocapacitive material of battery supercapacitor hybrids (BSH). Several morphologies are designed to achieve excellent surface properties and high energy storage ability. Large specific surface area and vigorous pore structure are easier to attain by constructing three-dimensional morphologies especially with hollow features. In this study, novel copper sulfide plate-assembled hollow cages are synthesized using solution and hydrothermal processes. The cage structure is formed for copper sulfide prepared using different hydrothermal temperatures, but pure copper sulfide composition is obtained only by using hydrothermal temperature higher than 130 degrees C. With the preferable morphology and composition, the copper sulfide electrode synthesized using 130 degrees C (Cu-O-S130) shows the highest specific capacitance (CF) of 292.1 F/g at 20 mV/s and excellent rate perfor-mance. The Cu-O-S130 positive electrode and a carbon negative electrode are used to assemble a BSH, which reaches a maximum energy density of 22.4 Wh/kg at 500 W/kg and CF retention of 80% and Coulombic effi-ciency larger than 95% after 7000 cycles. This work provides blueprints for designing efficient morphology of copper sulfide to achieve excellent energy storage ability.