Neoteric advancements in polybenzimidazole based polymer electrolytes for high-temperature proton exchange membrane fuel cells - A versatile review

The world's dependence on hydrocarbon fuel to generate power has proven to be the primary source of energy production. The emission of dangerous toxic and effluent gases during the process of hydrocarbon extraction and utilisation poses a massive threat to the environment and human life. This has driven the research into green energy technology; polymer electrolyte membrane fuel cells (PEMFCs) is one of the future century's bright green and clean energy producers. The most critical factor in the fuel cell is the polymer electrolyte membrane (PEM), which is the heart of the fuel cell assembly. Recently, polybenzimidazole (PBI)-based high-temperature polymer electrolytes have attracted researchers because they have high chemical and thermal stability combined with fillers that can control proton mobility. There are several limitations to the usage of PBI in high-temperature PEMFCs and this review summarizes the various structural modification: phase inversion, semi-interpenetrating IPNs, branched blocks and physical modification methods like crosslinking, blending, doping, progress done by various researchers to tackle the drawbacks in PBI-based polymer electrolyte membranes.