One-step electrodeposited NiS/CoS/NiS composite on Ni foam as high-performance electrode for supercapacitors.

Transition metal sulfides (TMSs) are considered as one of the promising electrode materials due to their fascinating redox reversibility and electronic conductivity. However, volume expansion during the charge/discharge process impedes their practical applications. The reasonable design of TMS electrode materials with unique morphology can improve the energy storage performance. Herein, we prepared the NiS/CoS/NiS composite that is grown on Ni foam (NF) a one-step electrodeposition process. The optimized NiS/CoS/NiS-7 shows a superhigh specific capacity of 2785.3 F g at 1 A g and remarkable rate capability. Furthermore, the as-assembled device displays a high energy density of 40.1 W h kg at a power density of 799.3 W kg and a satisfactory stability of 96.6% retention after 5000 cycles. This work provides a facile way to fabricate new TMS electrode materials for high-performance supercapacitors.