CoO@CoS/Ni3S2 hierarchical nanostructure arrays for high performance asymmetric supercapacitor

CoO@CoS/Ni3S2 (CoO@Ni-Co-S) hierarchical nanostructure electrode materials are synthesized on nickel foam (NF) through hydrothermal process and electrodeposition. The three dimensional porous CoO@Ni-Co-S hierarchical nanostructure is formed through the interconnection between the CoO nanoneedles and the Ni-Co-S nanosheets. This structure is beneficial for the transport of electrolyte ions and electrons. The CoO@Ni-Co-S nanocomposite exhibits a specific capacitance of 2507 F g(-1) at 1 A g(-1) (which is superior to CoO@CoS electrode, 1855 F g(-1) at 1 A g(-1)) and possesses a capacitance retention of 84.2% at 10 A g(-1). Furthermore, an asymmetric supercapacitor with CoO@Ni-Co-S//activated carbon is assembled, and the energy density reaches 110.7 W h kg(-1) when the power density is 880 W kg(-1). The asymmetric supercapacitor also exhibits an excellent cyclic stability (84.3% capacitance retention over 10,000 cycles). Preliminary results demonstrate that CoO@Ni-Co-S is a promising material for energy storage.