Electrodeposition of vanadium oxide–polyaniline composite nanowire electrodes for high energy density supercapacitors

Abstract

To meet the increasing demand for high energy density supercapacitors, it is crucial to develop positive and negative electrodes with comparable energy density. Previous studies have primarily focused on the development of positive electrodes, while negative electrodes are relatively less explored. Here we report an electro-codeposition method to synthesize a high performance negative electrode composed of a vanadium oxide (V₂O₅) and polyaniline (PANI) composite. Scanning electron microscopy revealed that the composite film is composed of one-dimensional polymer chains. Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) confirmed successful incorporation of V₂O₅ into PANI chains. Significantly, the V₂O₅–PANI composite nanowires exhibited a wide potential window of 1.6 V (between −0.9 and 0.7 V vs. SCE) and a maximum specific capacitance of 443 F g⁻¹ (664.5 mF cm⁻²). The flexible symmetric supercapacitor assembled with this composite film yielded a maximum energy density of 69.2 W h kg⁻¹ at a power density of 720 W kg⁻¹, and a maximum power density of 7200 W kg⁻¹ at an energy density of 33.0 W h kg⁻¹. These values are substantially higher than those of other pure V₂O₅ or PANI based supercapacitors. Moreover, the assembled symmetric supercapacitor device showed an excellent stability with 92% capacitance retention after 5000 cycles. The capability of synthesizing high performance composite electrodes using the electro-codeposition method could open up new opportunities for high energy density supercapacitors.