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

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.