CuCoO nanoneedle array with high stability for high performance asymmetric supercapacitors.

Cycling performance is very important to device application. Herein, a facile and controllable approach is proposed to synthesize high stability CuCoO nanoneedle array on a conductive substrate. The electrode presents excellent performances in a large specific capacitance up to 2.62 F cm (1747 F g) at 1 mV s and remarkable electrochemical stability, retaining 164% even over 70 000 cycles. In addition, the asymmetric supercapacitor assembled with the optimized CuCoO nanoneedle array (cathode) and active carbon (anode), which exhibits superior specific capacity (146 F g), energy density (57 W h kg), and cycling stability (retention of 83.9% after 10 000 cycles). These outstanding performances are mainly ascribed to the ordered binder-free nanoneedle array architecture and holds great potential for the new-generation energy storage devices.