Design of alkaline polyelectrolytes for high-performance and durable fuel cells and water electrolyzers

Anion exchange polymers (AEPs) are central to alkaline electrochemical energy technologies, including anion exchange membrane fuel cells and water electrolyzers, owing to their potential for high efficiency, reduced noble-metal usage, and improved durability. Significant progress has been achieved in polymer backbone design, cation chemistry, and membrane architecture, leading to major advances in hydroxide conductivity, alkaline stability, and device performance. However, challenges related to electrochemical degradation, mechanical failure, interfacial instability, and scalable processing continue to hinder commercialization. This review provides a polymer-science-focused overview of recent advances in AEP design, covering backbone engineering, cation selection, and structural strategies such as branching, crosslinking, reinforcement, and controlled ion-transport architectures. Particular emphasis is placed on degradation mechanisms under realistic operating conditions, including electrochemical, oxidative, and stress-induced mechanical degradation, which are often overlooked in conventional evaluations. The critical role of ionomer–membrane and ionomer–catalyst interfaces is highlighted, alongside emerging interfacial engineering strategies. Finally, forward-looking perspectives are offered to guide the rational development of durable, high-performance AEPs for practical alkaline electrochemical energy systems.