Cyclophane‐Architected Piperidinium Polymers With Intrinsic Microporosity Boost Ion Transport in High‐Performance Anion Exchange Membrane Fuel Cells

Abstract The rational design of anion exchange membranes (AEMs) with boosted ionic conductivity and alkaline stability is challenging, yet crucial for applied AEM fuel cells. Herein, a series of high‐performance AEMs are reported via integrating bridged cyclic [2.2]paracyclophane units with transannular π–π structure into poly(arylene piperidinium) frameworks. The resulting membrane leverages this bridged cyclic topology to generate localized intrinsic microporosity, which directly enhances ion transport efficiency through precisely engineered chemical channels. The engineered membrane simultaneously achieves remarkable hydroxide conductivity (137 mS cm ^‒1 @ 80 °C), coupled with well‐controlled swelling (≤23.1% @ 80 °C) and superior alkaline stability maintained for 5000 h. Since these excellent intrinsic properties, this AEM‐enabled fuel cell breaks the 1.5 W cm ^‒2 threshold in H ₂ ‐O ₂ (1.55 W cm ^‒2 @ 3.5 A cm ^‒2 ), while maintaining 1.07 W cm ^‒2 @ 2.9 A cm ^‒2 in H ₂ ‐air (CO ₂ ‐free). The fuel cell system demonstrates exceptional durability after over 200 h continuous operation, corresponding to an ultralow voltage decay rate of 25.8 µV h ^‒1 .