Growth of AgCoS@CNTs composite on nickel foam to enrich the redox active sites for battery-supercapacitor hybrid energy storage device

Supercapacitors are recognized as reliable energy storage technologies, despite obstacles such as inadequate energy density and comparatively small capacitance. In this study, we employed a hydrothermal synthesis method to fabricate silver cobalt sulfide (AgCoS) and doped it with carbon nanotubes (CNTs). The surface area of 19.35 m2/g was achieved with AgCoS@CNT//AC using BET measurements. The galvanostatic charge-discharge (GCD) measurements revealed a specific capacity of 1023 C/g for AgCoS@CNT. To construct an asymmetric device (AgCoS@CNT//AC), the best-performing AgCoS@CNT composite was employed as the positive electrode, while activated carbon (AC) served as the negative electrode. The specific capacity of the asymmetric device AgCoS@CNT//AC was measured to be 104 C/g, accompanied by a high power density of 750 W/kg and an impressive energy density of 32 Wh/kg. Notably, the columbic efficiency of the AgCoS@CNT//AC device reached 100% after 5000 consecutive cycles, while maintaining a capacity retention of 82%. These findings indicate that the AgCoS@CNT composite might serve as an intriguing material as an electrodes for supercapacitor applications.