Degradation-Resistant and High-Ionic-Conductivity Noncoplanar Poly(aryl ether Sulfone) Anion Exchange Membranes Via Cross-linking Strategy for Alkaline Water Electrolyzers

Achieving notable OH – conductivity and high stability of anion exchange membranes (AEMs) simultaneously is crucial for the commercial viability and environmental friendliness of AEM water electrolyzers for hydrogen production; however, this remains a huge challenge. Herein, a range of new fluorene-based macromolecular cross-linked poly(aryl ether sulfone) anion exchange membranes featuring flexible side chains with cations were developed via polycondensation, grafting, and implanting various cross-linking structures (imidazole ring and diamine chain types). Remarkably, the incorporation of imidazolium rings utilizing multicationic cross-linkers resulted in the formation of continuous ion channels for OH – due to the robust π-electron conjugation effect of the imidazolium rings that provided sufficient stability. With an exceptional performance of high OH – conductivity (130.95 mS/cm at 80 °C), the well-engineered Im@G-PAESA AEM also showcased a low swelling ratio (10.09% at 80 °C) and vigorous mechanical strength (41.95 MPa). Impressively, Im@G-PAESA retained a conductivity of 80.86% after prolonged immersion in 1 M NaOH over 1200 h (60 °C). Furthermore, water electrolyzer utilizing Im@G-PAESA-MEA attained a current density of 560.91 mA/cm 2 at 2.0 V and remained stable for a period of 72 h. Therefore, AEMs based on multi-imidazole cationic cluster cross-linked poly(aryl ether) exhibited broad practical application prospects in water electrolyzers.