Numerical analysis of asymmetric biomimetic flow field structure design for vanadium redox flow battery

Abstract

In redox flow battery systems, the design of the flow field structure significantly influences reactions, mass transfer, and electrolyte distribution within the battery. The uniformity of electrolyte distribution in the electrode is affected by the geometry of the main channel and distribution ports in the flow field. This study optimizes the flow field of vanadium redox flow battery (VRFB) based on biomimetic principles, designing an asymmetric vein bionic flow field. The branching structure of plant leaf veins can effectively control the flow of fluids, reduce turbulence and dead zones, and improve the distribution uniformity and flow efficiency of fluids. By analyzing the mechanisms through which flow field structure impacts internal battery processes, this work compares performance metrics, such as discharge voltage, porous electrode concentration, and pressure drop between symmetric and asymmetric flow fields. The results indicate that the electrolyte concentration at the inlet of the asymmetric flow field is at least 0.4 % higher than that of the symmetric, and the voltage efficiency of the asymmetric flow field improves by 0.13 %. The asymmetric flow field enhances the average concentration of the porous electrode by optimizing electrolyte distribution and increasing the infiltration of active species, thereby reducing polarization, lowering internal resistance, and improving the overall performance of the flow battery from multiple perspectives.