Exploring the redox characteristics of porous ZnCoS@rGO grown on nickel foam as a high-performance electrode for energy storage applications

Abstract

A supercapattery is a device that combines the properties of batteries and supercapacitors, such as power density and energy density. A binary composite (zinc cobalt sulfide) and rGO are synthesized using a simple hydrothermal method and modified Hummers' method. A notable specific capacity (C_s) of 1254 C g⁻¹ is obtained in the ZnCoS@rGO case, which is higher than individual C_s of ZnS (975 C g⁻¹) and CoS (400 C g⁻¹). For the asymmetric (ASC) device (ZnCoS@rGO//PANI@AC), the PANI-doped activated carbon and ZnCoS@rGO are used as the cathode and anode respectively. A high C_m of 141 C g⁻¹ is achieved at 1.4 A g⁻¹. The ASC is exhibited an extraordinary energy density of 45 W h kg⁻¹ with a power density 5000 W kg⁻¹ at 1.4 A g⁻¹. To check the stability of the device, the ASC device is measured for 2000 charging/discharging cycles. The device showed improved coulombic efficiency of 94%. These findings confirmed that the two-dimensional materials provide the opportunities to design battery and supercapacitor hybrid devices.