Quinuclidinium‐Based Microporous Anion Exchange Membranes for Water Electrolysis

Abstract Anion exchange membrane water electrolysis (AEMWE) is a promising green hydrogen production method; however, it is constrained by the moderate OH − conductivity and inadequate alkaline stability of anion exchange membranes (AEMs). Here we report a series of quinuclidinium‐based AEMs with branched and microporous structures, achieving 99.95% OH − conductivity retention after 3100 h in 10 M NaOH at 80 °C. By tuning the rigidity of the branching units to limit chain packing, micropores were created to enhance OH − transport, which improved the diffusion coefficient of OH − by 1.6 times within the poly (terphenyl‐triptycene‐quinuclidinium) (PTPQ‐Trip) membrane having the most rigid structure. An AEMWE configured with a PTPQ‐Trip membrane and nickel‐alloy catalysts can tolerate varied alkaline concentrations and deliver a hydrogen production current density of 2.8 A cm −2 at 2.0 V in 5 M KOH, which can be continuously operated at 0.5 A cm −2 and 30 °C for over 1200 h, with intentionally included stop/start interruptions. The assembled AEMWE demonstrated stable operation for 1400 h under alternating operational current densities and varying electrolyte temperatures. This work underscores the critical role of alkaline‐resistant microporous AEMs and highlights the adaptability of AEMWE for hydrogen production using renewable electricity.