“Structure-Catalysis” Integration: Synergistic Construction of Highly Catalytic VRFB Electrodes Using Defect-Moderated Fe-Coal-Based Carbon Nanofibers

Abstract Vanadium redox flow batteries (VRFBs) have garnered distinguished attention for their feasibility to enable cost-effective large-scale energy storage. Nonetheless, the electrochemical activity of electrodes is constrained during vanadium redox reactions, posing a problem for accomplishing high-performance VRFBs. Herein, we prepare a defect-rich Fe-coal-based carbon nanofiber electrode (Fe-ECNFs-600) via electrospinning followed by high-temperature carbonization. The Fe-ECNFs-600 contains moderate oxygen defects, Fe3O4 nanoparticles, and oxygen-containing functional groups, which can regulate the electronic structure, improve electrical conductivity, electrolyte wettability, and catalytic activity for the VO2+/VO2+ and V3+/V2+ redox couples. The VRFB with the Fe-ECNFs-600 electrode exhibits improved discharge capacity and energy efficiency compared with ECNFs-600 at 100 mA cm–2. This work may provide a defect regulation strategy for developing self-supporting electrode materials for VRFBs.