Flexible coaxial-type fiber supercapacitor based on NiCo₂O₄ nanosheets electrodes

Fiber electronic devices show advantages for the direct use as wearable and embedded device units or integrated textile modules. We successfully developed a coaxial-type flexible fiber supercapacitor by using NiCo₂O₄ nanosheets grown on Ni wire as the fiber electrodes. The volume capacitance of the fiber-shaped supercapacitor reached 10.3F/cm³ at a current of 0.08mA and outstanding cycling stability. An energy density of 1.44mWhcm^-3 and a power density of up to 17Wcm^-3 were also obtained for the fiber supercapacitor, which are almost 48-fold higher than the previous values. Furthermore, the coaxial-type fiber supercapacitor does not show any apparent degradation in the bending test, illustrating the promise for use as electrodes for portable and wearable energy storage.