Recent advances in anion-exchange membranes for electrolyzers, fuel cells and redox-flow batteries

Abstract

The performance of affordable electrochemical energy conversion and storage devices is primarily associated with developing efficient hydroxide-ion conducting anion-exchange membranes (AEMs) – a central component in these devices. Owing to their significantly lower cost compared to their proton-exchange membrane counterparts, AEM research has demonstrated significant progress in recent years in all aspects mainly in ionic conductivity and durability. In the last decade, remarkable advancements have been made in AEM research both in ionic conductivity and stability and in their successful implications for electrochemical devices. Therefore, in this review, we comprehensively discuss AEM structures, synthesis methods, key chemical and mechanical properties, and degradation mechanisms reported in the last eight years (2018–2025). We classified reported AEMs into four major categories based on cationic head groups: (i) quaternary ammonium, (ii) piperidinium, (iii) imidazolium and (iv) guanidinium. We covered AEM implementation in electrochemical devices – anion-exchange membrane water electrolyzers, anion-exchange membrane fuel cells, and vanadium redox-flow batteries which is highly useful for their practical applications. Finally, we present the significant progress made, remaining challenges and future directions to advance fast-growing AEM research for the development of affordable and sustainable energy devices.