Enhanced OH− Conductivity and Alkaline Stability of Anion Exchange Membranes via Pyrene Stacking Backbone for Water Electrolysis
Anion exchange membrane water electrolyzers (AEMWEs) offer a cost-effective route for green hydrogen production by enabling non-precious metal catalysts and rapid start-stop operation. However, the trade-off between hydroxide conductivity and alkaline stability of anion exchange membranes (AEMs) remains a critical bottleneck. This study introduces a pyrene-based π-π stacking strategy to simultaneously enhance both properties. The synergistic π-stacking networks in the polymer backbone induce long-range cation aggregation through directed self-assembly, generating ionic cluster microdomains that elevate local hydroxide concentration and increase the density of accessible ion hopping sites. Additionally, the electron-donating effect of pyrene reduces the electrostatic potential of β-H adjacent to quaternary ammonium cations, raising the energy barrier for OH− nucleophilic attack. The resulting AEM exhibits exceptional performance: a hydroxide conductivity of 160 mS/cm and merely 0.35% conductivity degradation after 1950 h in 2 M KOH at 80 °C. The membrane electrode assembly (MEA) achieves a current density of 2.58 A/cm2 at 1.8 V and maintains stable operation for over 700 h in durability testing. These findings demonstrate a viable pathway for developing high-performance AEMs that meet the rigorous demands of industrial water electrolysis.