Impact of Advances in Anion Exchange Membranes and Ionomers on Alkaline Fuel Cells.

The operation of low-temperature electrochemical energy conversion systems (fuel cells, electrolyzers) at high pH values is of perennial interest due to the possibility of moving away from expensive platinum group metal catalysts and reducing cost. Historically, the anion exchange membranes (AEMs) and ionomers have been hampered by performance (ionic conductivity, mechanical strength) and chemical stability issues. In this context, select developments over the past decade in alternate AEM chemistries, water management methods, and production of membrane electrode assemblies (MEAs) that have enabled a significant leap in performance of alkaline fuel cells are examined. These developments are linked to performance improvements in alkaline H₂/O₂ fuel cells and also consider developments in alkaline fuel cells using nitrogen-containing fuels (ammonia, hydrazine), carbon-containing fuels (alcohols, glycols), and boron-containing fuels (sodium borohydride, ammonia borane). Finally, current challenges and bottlenecks are identified, and potential solutions are proposed.