CuCo₂O₄ Nanowires Grown on a Ni Wire for High‐Performance, Flexible Fiber Supercapacitors

Flexible/stretchable supercapacitors for energy harvesting and storage are being extensively studied to meet the demand of specific environments. We successfully fabricated a flexible fiber supercapacitor through a simple and rapid single‐step hydrothermal method, growing CuCo 2 O 4 nanostructures on Ni wires to be used as fiber electrodes. Electrochemical investigations demonstrate that the electrode material can be used in a supercapacitor to give a remarkable performance. The high‐rate specific capacitance of the fiber‐shaped supercapacitor reached 11.09 F g −1 at a current of 2 mA and outstanding cycling stability with about 93.5 % retention at 4 mA after 4000 charge/discharge cycles. Furthermore, the flexible fiber supercapacitor does not show any apparent degradation in the bending test, illustrating its potential to be used in portable and wearable energy‐storage devices.