Conducting polymers/oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth as advanced electrodes for high-performance supercapacitors

The low energy density of supercapacitors (SCs) is one of the main factors restricting their development. WO3 with high theoretical capacitance is an ideal n-type material for anode electrode, but its narrow potential window and low conductivity are not conducive to the application of high-energy-density SCs. Herein, a high electrochemical activity poly(indole-5-carboxylic acid) (P5-ICA) as p-type material wrapping n-type oxygen vacancies WO3 vertically nanowire arrays supported on carbon cloth is prepared by hydrothermal method and subsequent electrodeposition method. This adhesive free flexible p/n-type hetero-structural P5-ICA@WO3 vertical nanowire array electrode has a three-dimensional porous nanostructure that not only provides a large surface area, but also promotes the penetration of electrolyte ions and the transmission of electrons. It is found that the P5-ICA@WO3 nanowire array with high areal specific capacitance (1430 mF cm−2 at 4 mA cm−2) and long cycle stability (94 % after 6000 cycles) exhibits a widened electrochemical activity window compared to individual material. The symmetrical SCs assembled using P5-ICA@WO3 can provide a high areal energy density of 137.6 μWh cm−2 at the power density of 1.4 mW cm−2, which is significantly higher than the SCs performance of previously used WO3-based electrode materials.