Distinct Activation Mechanisms of Carbon Felt Electrodes for Various Redox Couples in Flow Batteries

ABSTRACT The large‐scale deployment of redox flow batteries (RFBs) remains constrained by sluggish catalytic kinetics within carbon felt electrodes, causing severe polarization losses. Addressing this necessitates system‐specific electrode activation strategies tailored to the distinct mechanisms of various redox couples. This review systematically analyzes catalyst modification advancements across four key RFB configurations: vanadium, zinc‐based, iron‐based, and organic systems. We establish definitive mechanistic pathways by correlating performance enhancements with specific electrochemical activation dynamics. Specifically, vanadium RFBs leverage atomic‐scale defect engineering and Bi‐centric catalysis to accelerate reaction kinetics. Zinc‐based systems employ zincophilic nanostructures (e.g., CuO) to ensure uniform nucleation and suppress dendrite growth. Iron‐based architectures integrate high hydrogen evolution overpotential materials, such as Pb and Bi, to mitigate parasitic reactions. Finally, organic RFBs focus on advanced surface functionalization to maximize active site density and stability. By synthesizing these strategies, this work provides comprehensive guidelines for optimizing electrode functionality across distinct RFB architectures.