Scalable superacid-reduced synthesis of ultrastable anion exchange membrane (PAMQ) for water electrolysis

Green hydrogen production via anion exchange membrane water electrolysis (AEM-WE) promises cost-effective decarbonization, but faces durability and scalability constraints from chemically unstable AEM and the excessive use of superacid in polymerization. Here, we report a poly(aryl methylquinuclidinium) (PAMQ) synthesized via a superacid-reduced polyhydroxyalkylation approach employing aldehyde-functionalized quinuclidine monomers. This strategy reduces trifluoromethanesulfonic acid (TFSA) consumption by 62.5% versus ketone-based systems, while integrating sterically protected quinuclidinium cations that resist β-H elimination and nucleophilic substitution. Crucially, streamlined synthesis mitigates the risks of superacid polymer reactions during scale-up, enabling pilot-scale production and roll-to-roll membrane fabrication. PAMQ achieves benchmark hydroxide conductivity (170 mS cm^-1 at 90 °C) with a low swelling ratio (13.16%) and exceptional alkaline stability, showing negligible degradation after 10,000 h in 1 mol L^-1 KOH (80 °C), and an exponential fit indicates a 10% decay occurs over a decade. In fully non-platinum group metal AEM-WE, it achieved 7.70 A cm^-2 at 2.0 V, operating stably for over 2500 h at 1 A cm^-2 (80 °C) with a minor fading rate of 12.97 μV h^-1. The performance and stability of PAMQ were validated at a kilowatt-level stack, demonstrating the transformative potential of PAMQ-based AEMs to advance the sustainable hydrogen economy.