Recent advances in optimized polybenzimidazole-based membranes for vanadium redox flow battery applications

Polybenzimidazole(PBI)-based membranes have garnered significant interest in advancing vanadium redox flow batteries (VRFBs) due to their excellent chemical stability, high mechanical strength, and promising ion-selectivity properties. Recent research has focused on optimizing PBI membranes through chemical modifications, composite formations, and hybridization techniques, which enhance proton conductivity while minimizing vanadium ion crossover. Techniques such as sulfonation, blending with inorganic fillers (e.g., silica, TiO₂), and incorporation of functionalized nanomaterials have resulted in membranes with improved performance, enabling higher energy efficiencies and extended cycle life in VRFBs. Additionally, new synthesis methods for cross-linking and microstructure adjustments have yielded enhanced durability and flexibility in various operating conditions. These advancements highlight the potential of optimized PBI-based membranes to play a crucial role in developing efficient and durable energy storage systems for grid-scale applications. • PBI-based membranes exhibit high proton conductivity and excellent chemical stability in VRFB environments. • Low vanadium ion crossover of PBI based membranes extends battery cycle life. • Nanocomposite modifications improve mechanical strength, thermal stability, and overall performance. • Cost-effective and scalable alternative to Nafion, reducing VRFB system costs. • Functionalized PBI membranes show promising potential for next-generation energy storage.