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

[Display omitted] •CoO@Ni-Co-S is synthesized by the hydrothermal process and electrodeposition.•The nanostructure provides short diffusion paths and abundant electroactive sites.•Bi-component metal sulfide can improve conductivity and electrochemical activity.•The energy density of asymmetric supercapacitor is 110.7 W h kg−1 at 880 W kg−1. 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.