Co-electrodeposition hybrid reduced graphene oxide and nickel-cobalt selenide nanosheets on silicon nanowires for high-performance supercapacitor

Due to inherent compatibility with IC technology, 3D silicon is prone to build a skeleton for the energy storage electrodes. Herein, a unique 3D hierarchical core-shell electrode was first developed with silicon nanowire arrays (SiNWs), metal selenide (TMSe) and reduced graphene oxide (RGO) nanosheets, where SiNWs decorated with Ni particles (Si/Ni) served as the conductive core and co-electrodeposited hybrid nickel-cobalt selenide (NCSe) and RGO nanosheets (NCSe-RG) functioned as the high capacitive outer shell. Owing to the synergy effect between NCSe and RGO, high-speed electron transport channels of Si/Ni, and abundant electroactive sites of porous NCSe layer, the synthesized Si/Ni/NCSe-RG electrode delivered a large capacitance of 2268 F g-1 (1973 mF cm-2) at 1 A g-1 which was higher than most reported silicon-based electrodes, and an excellent rapid-charging capability (1540 F g-1 at 30 A g-1). Furthermore, a solid asymmetric supercapacitor (SC) was prepared by using Si/Ni/ NCSe-RG as the positive electrode, demonstrating an excellent energy density of 53.23 Wh kg-1 at the power density of 800 W kg-1. Our results suggest that high-performance SC electrodes can be engineered with TMSe and 3D silicon with a simple and time-saving method.