A new binder-free ZnS-CuO microsphere: A battery-type electrode material for asymmetric supercapacitor

The supercapacitor has emerged as a viable solution to address the energy demands of industries and mitigate the environmental concerns associated with fossil fuel utilization. Hence, in this study, binder-free ZnS-CuO microspheres are reported for the first time and directly utilized as a battery-type electrode for asymmetric supercapacitor (ASC) applications. The current study demonstrates an exceptional electrochemical performance by optimizing the composition, structure, and morphology. The increased surface area and abundance of active sites contribute to the enhanced ion transfer efficiency between the electrolyte and the electrode, promoting rapid ion exchange. The electrochemical properties reveal a maximum capacitance of 561 F/g with excellent charge storage capacity, and good rate capability. The CuO-ZnS||AC ASC was built that operates in a broad voltage window of 1.6 V, and a capacitance of 175 F/g in an aqueous solution. It delivers the highest specific energy of 62 Wh/kg with an excellent power delivery of 8640 W/kg and remarkable stability of 93.2 % after 5000 cycles. Nevertheless, there is a prevailing optimism regarding the potential for optimizing synthesis procedures, which may ultimately result in the practical implementation of these innovative materials for efficient energy storage in the near future.