Study of the Kinetics of Vanadium (II)/(III) Redox Reaction

Vanadium redox flow battery (VRB) is a novel electrical energystorage system. The cell voltage loss is mainly due to the sluggishreaction of these redox reactions, it also affects the overall VRBenergy storage efficiency. Rotating disk electrode (RDE) was usedto measure the polarization curves of V(IV)/(V) and V(II)/V(III)redox reactions in different electrolyte compositions. On Carbonelectrode, the rate constants of V(IV) oxidation is much slowerthan the rate constant of V(II) oxidation. The mainly voltage lossis due to the V(IV)/(V) in the electrolytes on positive electrode.We also found that the Stoke radius of V(IV)/V(V) ion is largerthan the Stoke radius of V(II)/V(III). This provides a reasoning oflower reaction constant of V(IV)/V(V) ion pair.