Synthesis of Cross-Linked Poly(aryl Piperidinium) Anion-Exchange Membranes with Robust Alkaline and Mechanical Stability for Fuel Cell Applications

The development of alkaline-stable and mechanically robust anion-exchange membranes (AEMs) is crucial for advancing AEM-based fuel cells (AEMFCs), water electrolyzers (AEMWEs), CO₂ electrolyzers (AEMCO₂Es), direct ammonia fuel cells (DAFCs), and vanadium flow batteries. In this work, efficient AEMs were fabricated by chemically cross-linking quaternized poly(vinyl pyridinium) (QPVP) with quaternized poly(aryl piperidinium) (QPAP) to simultaneously enhance ionic conductivity, alkaline stability, mechanical integrity and electrochemical performance. The optimized cross-linked membrane exhibited enhanced hydroxide transport achieving a maximum conductivity of 128.4 mS cm^–1 at 90 °C compared to 68.8 mS cm^–1 for the pristine membrane. This improvement is attributed to the formation of a well-connected ionic network and improved phase-separated morphology induced by cross-linking. In addition, the cross-linked membranes demonstrated superior alkaline durability, retaining stable conductivity after prolonged exposure to harsh alkaline conditions. Electrochemical performance evaluation in H₂/O₂ AEMFC single cell showed that the optimized membrane achieved a peak power density of 0.88 W cm^–2 with a current density of 2.04 A cm^–2 at 80 °C significantly outperforming the pristine membrane. These results demonstrate that the cross-linked QPVP-QPAP membrane is an effective strategy for developing high-performance AEMs suitable for next-generation energy conversion and hydrogen production technologies.