Electrode made of NiCo double hydroxide on oxidized activated carbon for asymmetric supercapacitors

• Strong coupling was established between NiCo-DH and OAC by oxidation modification. • NiCo-DH@OAC exhibited excellent electrochemical performance for synergistic effects. • ASCs were demonstrated effective in solar panel integrated supercapacitors. NiCo double hydroxide (NiCo-DH) and oxidized activated carbon (OAC) were used to synthesize a three-dimensional (3D) NiCo-DH@OAC via hydrothermal method. OAC acts as the support for in-situ growth of NiCo-DH nanowires, and oxygen-containing groups on the surface of OAC are crucial for the uniform loading of NiCo-DH and keeping structural stability of the composites. Due to the synergistic effect between NiCo-DH and OAC, NiCo-DH@OAC presents an excellent specific capacitance (1990 F g -1 at 1 A g -1 ). The asymmetric supercapacitor (ASC) is assembled with NiCo-DH@OAC as the positive electrode and OAC as the negative electrode, and exhibits a superior energy density (46.5 W h kg −1 at 800 W kg −1 ) and a cycling stability (90.7% after 10,000 cycles). Furthermore, ASC has been demonstrated effective in solar panel integrated supercapacitors.