Towards an all-vanadium redox flow battery with higher theoretical volumetric capacities by utilizing the VO2+/V3+ couple

An all-vanadium redox flow battery with V(IV) as the sole parent active species is developed by accessing the VO2+/V3+ redox couple. These batteries, referred to as V4RBs, possess a higher theoretical volumetric capacity than traditional VRBs. Copper ions were identified as an effective additive to boost the battery performance.