Investigating the Coupled Influence of Flow Fields and Porous Electrodes on Redox Flow Battery Performance



At the core of redox flow reactors, the design of the flow field geometry –which distributes the liquid electrolyte through the porous electrodes– and the porous electrode microstructure –which provides surfaces for electrochemical reactions– determines the performance of the system. To date, these two components have been engineered in isolation and their interdependence, although critical, is largely overlooked. Here, we systematically investigate the interaction between state-of-the-art electrode microstructures (a paper and a cloth) and prevailing flow field geometries (flow through, serpentine and four variations of interdigitated). We employ a suite of microscopic, fluid dynamics, and electrochemical diagnostics to elucidate structure-property-performance relationships. We find that interdigitated flow fields in combination with paper electrodes –which features a uniform microstructure with unimodal pore size distribution– and flow-through configurations combined with cloth electrodes –which have a hierarchical microstructure with bimodal pore size distribution– provide the most favorable trade-off between hydraulic and electrochemical performance. Our analysis evidences the importance of carrying out the co-design of flow fields and electrode microstructures in tandem. We hope these results can help researchers and technology practitioners in the design of electrochemical cell for convection-enhanced electrochemical technologies.


Supplementary material

Supplementary material for Investigating the Coupled Influence of Flow Fields and Porous Electrodes on Redox Flow Battery Performance
Flow cell configuration for pressure drop measurements, reproducibility of the electrochemical experiments, additional X-ray tomographies of the paper and cloth electrodes, capacitance measurements for ECSA estimation, Darcy-Forchheimer fitting parameters from the hydraulic analysis, contribution of flow field and electrode components to the total pressure drop in the cell, additional polarization measurements at different electrolyte velocities for the paper and cloth electrodes, electrochemical impedance spectroscopy fittings for all electrode-flow field configurations at different electrolyte velocities, and analysis of the mass transfer resistances as a function of electrolyte velocity.