Stable Anion Exchange Membrane Based on Poly(Norbornene)s Suspended With Piperidinium for Water Electrolysis

ABSTRACT To address the challenge of synergistically enhancing both conductivity and durability in anion exchange membranes (AEMs), this study synthesized a polynorbornene‐based AEM (H‐aPNB‐QPIP‐1.85) through a molecular design featuring an “all‐hydrocarbon backbone, flexible alkyl side chains, and pendant piperidinium cations.” The all‐hydrocarbon backbone provides fundamental stability, the flexible alkyl side chains promote microphase separation, and the conformation‐restricted piperidinium cations synergistically enhance both conductivity and chemical stability. The membrane exhibits an excellent ionic conductivity of 104.4 mS cm −1 and demonstrates exceptional alkaline stability by retaining 96.9% of its conductivity after 1200 h of testing. In a water electrolyzer, it achieves a high current density of 3.4 A cm −2 at 2.0 V and maintains excellent durability over 100 h of operation. This work provides an effective material strategy for advancing high‐performance AEMs in green hydrogen production.