In Situ Potential Distribution Measurement and Validated Model for All-Vanadium Redox Flow Battery

An in situ, local potential measurement technique was further developed and applied to all-vanadium redox flow batteries to determine the potential distribution within multilayer electrodes of the battery. Micro-scale potential probes enabled in situ measurement of local potential in electrode layers between the cell flow field and membrane. The local redox potentials were recorded for different operating conditions and states of charges. To further analyze the behavior of potential distribution in the through-plane direction, a mathematical model was developed and the species distribution as well as the flux density of any individual component was modeled in terms of contributions from convective, diffusive and electrophoretic fluxes at each operating condition. Good agreement was achieved between the mathematical model prediction and experimental data with maximum error of 8%. Both mathematical simulation and experimental data confirmed the distribution of potential in the through plane direction as a function of discharge current density, predicting the lowest potential in a region close to the flow plate.