A simple model for the vanadium redox battery

A two-dimensional stationary model, based on the universal conservation laws and coupled with electrochemical reactions, is applied to describe a single all-vanadium redox flow cell. Emphasis is placed on studying the effects of applied current density, electrode porosity and local mass transfer coefficient on the cell performance. The model results indicate that bulk reaction rate depends on the applied current density. The transfer current density and over-potential increase almost twice as the applied current density doubled. A decrease in electrode porosity leads to a more rapid depletion of the reactant concentration, a higher integral average value of the transfer current density and a more uniform distribution of the over-potential. The local mass transfer coefficient only affects the value of the over-potential.