Study of ABPBI membrane as an alternative separator for vanadium redox flow batteries

Abstract

AbstractVanadium redox flow batteries are receiving great attention due to their capabilities of offering multiscale energy‐storage and cross‐contamination‐free system. Ion‐exchange membrane (IEM), which is one of the critical components in the vanadium redox flow battery (VRFB) system, simultaneously prevents the cross‐mixing of active vanadium species, and facilitates the movement of the proton. The cross‐mixing of the vanadium species influences coulombic efficiency (CE), whereas the proton movement influences the voltage and energy efficiency (EE). Hence, IEM plays a major role in the performance of the battery in terms of self‐discharge rate, CE, crossover of active material, and ionic conductivity. In the present work, the suitability of an alternative low‐cost, efficient, and durable membrane, which are essential for providing a sustainable solution for VRFB, is studied. 2,5‐Polybenzimidazole membrane is studied as an alternative membrane and evaluated in a VRFB with mixed electrolyte, which has the potential to offer a substantial reduction in the cost. The mixed electrolyte helps in extending the operating temperature. 2,5‐Polybenzimidazole membrane‐based VRFB shows CE, EE, and voltage efficiency as 99%, 83%, and 84%, respectively, which is comparable to Nafion membrane.