Smart design of free-standing ultrathin Co-Co(OH)2 composite nanoflakes on 3D nickel foam for high-performance electrochemical capacitors

Ultrathin Co-Co(OH)2 composite nanoflakes have been fabricated through electrodeposition on 3D nickel foam. As electrochemical capacitor electrodes, they exhibit a high specific capacitance of 1000 F g-1 at the scan rate of 5 mV s-1 and 980 F g-1 at the current density of 1 A g-1, respectively, and the retention of capacitance is 91% after 5000 cycles.