Study of the Electrochemical Behavior of High Voltage Vanadium-Metal Hydride Hybrid Semi-Flow Battery

Abstract

A vanadium-MH rechargeable semi-flow battery hybridizing the V4+/V5+ redox couple (positive) with the metal hydride (negative) was investigated. This battery has a higher cell voltage and the V(II)/V(III) redox couple is absent, hence avoiding the problems of V2+ oxidation. An experimental open circuit voltage of 1.86 V and an operating voltage of 1.65 V for this hybrid battery were obtained. These are very high values among all rechargeable flow batteries. The system demonstrated superior stability, reversibility, and efficiencies in coulomb (97%), energy (81.3%), and voltage (83.8%).