Integrating Flow Field Geometries within Porous Electrode Architectures for Enhanced Flow Battery Performance

Abstract The large‐scale adoption of renewable energy demands efficient and cost‐effective storage solutions, with redox flow batteries (RFBs) emerging as promising candidates for grid‐scale applications. However, their deployment remains constrained by high capital costs, largely driven by the need for advanced porous electrodes that balance high surface area, efficient mass transport, and low‐pressure drop. Compared to conventional, carbon‐fiber‐based porous electrodes, non‐solvent induced phase separation (NIPS) offers a versatile manufacturing approach to tailor electrode microstructures and enhance electrochemical performance, yet optimizing mass transport remains a key challenge. Here, a micro‐patterning strategy is introduced that directly integrates flow field architectures into the electrode structure during NIPS fabrication as a potentially scalable manufacturing approach. Inspired by flow field designs used in fuel cells and flow batteries, we imprint groove and pillar micro‐patterns to enhance in‐plane and through‐plane mass transport. Using symmetric iron flow cells and all‐vanadium full cells, pillar‐patterned electrodes, combined with an interdigitated flow field, are shown to significantly reduce mass transfer resistance and improve electrochemical performance while maintaining a low‐pressure drop. This work presents a simple, scalable, and cost‐effective electrode design strategy to boost RFB power density and advance the economic viability of redox flow battery technology.