Macromolecular reinforcement of alkaline ion-solvating polymer electrolytes

Alkaline ion-solvating polymer electrolyte membranes derived from poly(isatin biphenyl) and polybenzimidazole (m-PBI) blends with different ratios were prepared, characterized, and evaluated as electrode separators in alkaline water electrolysis. The physicochemical properties could be tuned by varying the composition of the blend, and the membrane with a poly(isatin biphenyl) content of 25% showed a suitable balance between conductivity and mechanical robustness. The polarization behavior was comparable to that of state-of-the-art separators, with significantly lower H2 crossover. No signs of degradation could be observed after 70 h of electrolysis testing in 30% aqueous KOH at 80 °C, supporting that macromolecular reinforcement is a promising way forward in the development of high-performing and durable alkaline ion-solvating membranes for water electrolysis.