Electrochemical properties of V₂O₅/carbon composite electrodes in aqueous solutions

The reaction mechanism of V₂O₅ xerogel and the electrode properties of V₂O₅/carbon composites in an aqueous electrolyte solution were examined to obtain high-performance electrodes for rechargeable proton batteries. Based on the results of the chemical analysis of the electrode, proton intercalation is suggested to be the dominant reaction mechanism. By using the relationship between the capacity and current density of a thin-film electrode consisting of V₂O₅ xerogel, the diffusion coefficient in the V₂O₅ xerogel was determined to be 8 ± 1 × 10⁻¹¹ cm² s⁻¹. The V₂O₅/carbon composite electrode was prepared by drying a homogeneous dispersion of carbon particles in the V₂O₅ sol. The composite electrodes showed a large capacity of 460 mAh g⁻¹ at a current density of 1 A g⁻¹ and maintained a relatively large capacity of 160 mAh g⁻¹ at 100 A g⁻¹. These properties were attributed to the homogeneous microstructure of the V₂O₅/carbon composites. The V₂O₅/carbon composite electrodes were thus revealed as high-performance electrodes with large capacities and excellent high-rate capabilities.