Ultrafast modification of commercial graphite felts with high catalytic activity for efficient electrolytic preparation of vanadium electrolytes based on V2O5

Flow electrolysis is regarded as the most promising approach for producing high-quality and pure vanadium electrolytes. However, it faces challenges due to sluggish electrode reaction kinetics, resulting in high energy consumption and relatively low preparation efficiency. To address this issue, we propose a rapid electrode modification method that combines low-pressure plasma treatment with KMnO 4 etching. The catalyst MnO 2 , formed on carbon fiber, effectively enhances the electrode's electrocatalytic performance. The findings from the electrochemical analysis demonstrate that the modified electrode displays markedly enhanced electrocatalytic activity for the redox reaction of V 4+ /V 3+ . Flow electrolysis tests reveal that the electrolysis system with the modified electrode consumes 35.78 % less energy than the original graphite felt at a high current density of 300 mA/cm 2 , ten times higher than previously reported. Notably, the efficiency of the electrolyte prepared using the modified electrode in vanadium redox flow batteries (VRFB) achieves 98.13 % (coulombic efficiency), 86.88 % (volumetric efficiency), and 85.26 % (energy efficiency) at 100 mA/cm 2 , comparable to the electrolyte produced with the original electrode. This demonstrates the viability of employing the proposed graphite felt to efficiently fabricate V 3.5+ electrolytes with low energy consumption at high current densities.