Building Four‐Armed Nodes in Anion Exchange Membranes for Durable Water Electrolysis With High Current Density

ABSTRACT Anion exchange membrane water electrolysis (AEMWE) holds enormous potential for renewable energy. However, the simultaneous achievement of high ionic conductivity and long‐term durability in membranes is still a significant challenge. Here, we report a neopentane‐crosslinked anion exchange membrane (AEM) based on ether‐free poly(aryl piperidinium) (n‐QPTM‐ x ), in which four‐armed tetrahedral crosslinking nodes simultaneously suppress excessive swelling and regulate microstructure. This unique architecture promotes cation aggregation to form continuous ion‐transport pathways while eliminating β ‐hydrogen‐containing degradation sites, thereby enhancing alkaline stability. As a result, the optimal membrane achieves a remarkable hydroxide conductivity of 200.0 mS cm ⁻¹ with a limited swelling ratio of 15.9% at 80°C, and retains over 92.3% of its cationic groups after 3000 h in 1 M KOH. In a single‐cell electrolyzer, n‐QPTM‐5 achieves remarkable current densities of 11.9 A cm ⁻² and 9.5 A cm ⁻² at 2 V by using IrO ₂ and Ni‐Fe alloy as anode catalysts, respectively. Importantly, the Ni‐Fe‐based AEMWE sustains steady performance for more than 2400 h at 1 A cm ⁻² and 1000 h at 2 A cm ⁻² with minimal voltage losses of 17 and 33 µV h ⁻¹ , respectively, demonstrating a promising pathway for fabricating high‐performance AEMs in water electrolysis applications.