Synergistic Microchannel Design and Oxygen Functionalization Electrode for High-Performance Vanadium Redox Flow Batteries

Vanadium redox flow batteries (VRFBs) show significant potential for grid-scale energy storage, yet face challenges due to sluggish electrode kinetics and inefficient electrolyte transport. To address these limitations, we present a dual-functional graphite felt (K-GF) electrode that synergistically integrates engineered microflow channels with oxygen-containing functional groups. The K-GF electrode is synthesized through a sustainable thermal and water vapor activation process using polyacrylonitrile (PAN) fibers, which eliminates toxic chemical treatments and minimizes water waste, thus aligning with green manufacturing principles. The engineered microflow channels enhance electrolyte dynamics, while the functional groups improve electrocatalytic activity, collaboratively addressing the existing limitations. Consequently, VRFBs equipped with K-GF electrodes demonstrate an energy efficiency of 85% at 100 mA cm–2 and a power density of 495 mW cm–2. Additionally, the battery operates consistently for 600 cycles at 300 mA cm–2 with an impressive energy efficiency of 72%. Computational fluid dynamics (CFD) simulations validate that the microflow channels optimize electrolyte dynamics, ensuring uniform reactant distribution and maximizing active-site utilization. Therefore, this work provides a transformative pathway for VRFBs in practical grid storage.