In Situ Single Electrode Studies of an All-Vanadium Redox Flow Battery

Abstract

We use polarization curves and a dynamic hydrogen reference electrode (DHE) to study the effects of electrode material and state of charge on all-vanadium redox flow battery (VRB) performance. The current trend in studying these systems is to evaluate new materials or designs based on voltage, charge and power efficiency metrics. However, such characterization does not allude to which processes may be limiting performance or which electrode dominates performance loss. At moderate state of charge, the negative electrode dominated cell overpotential at all current densities. As state of charge increased, the overpotential was dominated less by the negative electrode. Thicker carbon paper showed better performance while partially wet-proofed carbon paper had a negative impact on performance compared to untreated carbon paper. Through improvements made to the design and materials, VRB power output increased from 77 mW/cm2 to 404 mW/cm2.