Synthesis of Au-V2O5 composite nanowires through the shape transformation of a vanadium(iii) metal complex for high-performance solid-state supercapacitors

Abstract

A simple redox transformation between a vanadium(III) metal complex and gold(III) chloride aided by a cost-effective modified hydrothermal procedure has been adopted for the synthesis of Au-V₂O₅ composite nanowires. The stability of pseudocapacitive electrode materials in acidic electrolytes is a major challenge. However, the synthesized Au-V₂O₅ composite nanowires are stable in acidic electrolyte when compared to the precursor component, V₂O₅. Electrochemical measurement shows a specific capacitance of 419 F g⁻¹ at 1 A g⁻¹ current density in 0.5 M H₂SO₄ solution for the synthesized composite nanowires. However, the precursor component V₂O₅ shows a lower specific capacitance under identical conditions. The synthesized composite nanowires, as a pseudocapacitive electrode material, respond to a wide range of working potential windows (+1.6 V), resulting in maximum energy and power densities of 53.33 W h kg⁻¹ and 3.85 kW kg⁻¹ respectively. Moreover, the Au-V₂O₅ nanowires show high cyclic stability (89% specific capacitance retention) for up to 5000 consecutive charge–discharge (CD) cycles at 10 A g⁻¹ constant current density, due to the composite formation by redox transformation, which reflects the stability of the composite in acidic electrolyte.