MXene-SnO 2 modified carbon felt electrode for improved performance of vanadium redox flow batteries

Abstract The carbon felt electrode plays a critical role in vanadium redox flow batteries. However, its electrochemical performance is often limited by poor reaction reversibility arising from the strong solvation of vanadium ions in the electrolyte. This strong solvation hinders efficient electron transfer at the electrolyte-electrode interface, leading to increased interfacial resistance. In this study, a MXene-SnO 2 composite is coated onto carbon felt to regulate the interfacial environment and overcome these limitations. The oxygen-containing surface groups of SnO 2 are expected to interact with hydrated vanadium ions, which may facilitate partial weakening of the solvation shell prior to the redox reaction, while MXene provides high electrical conductivity and stabilizes interfacial charge transfer. Electrochemical results confirm that the modified electrode exhibits enhanced reversibility and reduced interfacial resistance compared with pristine carbon felt. Therefore, regulating interfacial interactions at the electrode surface through MXene-SnO 2 modification represents a promising strategy.