Anion-Exchange Membranes for Fuel Cells: Synthesis Strategies, Properties and Perspectives

This review focuses on various synthesis strategies of anion-exchange membranes (AEMs) for fuel cells, diverse methodologies of AEM-forming, together with relationship between structures and properties. AEMs are discussed from seven categories, including (1) AEMs derived from Nafion precursors with sulfonyl fluoride groups, which display excellent stability and well-developed morphologies that similar to Nafion, but has potentially high costs. (2) AEMs prepared by grafting technologies, such as chemical grafting technique, ATRP technique, plasma grafting technique and radiation grafting technique. (3) AEMs based on functionalized commercial polymers, including PVA, SEBS, CPP, PEEK, PES, PEI, PPO, and so on. (4) AEMs prepared by newly-synthesized polymers, in which the most interesting approach is to synthesize alkaline multi-block copolymers with enough long hydrophilic/hydrophobic blocks. (5) AEMs containing heterogeneous composition, which mainly prepared by blending and sol-gel methods, reinforced or pore-filling AEMs and IPN or s-IPN. (6) AEMs with functional groups different from quaternary ammonium, which includes the studies of new type of AEMs with highly chemical stability in alkaline solution. (7) Hybrid membranes combining AEM with PEM, in which new configuration results in different performances. At last, conclusions and perspectives for the future researches of AEMs are presented.