Facile synthesis of core-shell NiSe@α-Ni(OH)2 as battery-type electrode for high-performance hybrid supercapacitor

Abstract In this study, core-shell NiSe@α-Ni(OH)2 with NiSe nanorod wrapped in α-Ni(OH)2 nanosheet is successfully prepared on Ni-foam via a facile two-step hydrothermal synthesis. Ni-foam takes the roles of the conductive substrate and source of Ni during the synthesis of NiSe. Thus the strong adhesive force between the as-prepared NiSe and Ni-foam is formed, making the nanorod become a bridge to facilitate electron transfer and a skeleton to support α-Ni(OH)2 nanosheet. Utilizing the comprehensive advantages of the core-shell architecture and compositional features, the obtained NiSe@α-Ni(OH)2 exhibits an areal capacity of 1.780 mAh cm−2 at the current density of 3 mA cm−2 and an excellent rate capability. The assembled hybrid supercapacitor NiSe@α-Ni(OH)2//AC exhibits an energy density of 55.92 Wh kg−1 at the power density of 186.9 W kg−1, and 75.10% of the initial capacity is retained after 4500 cycles.