Anion Exchange Ionomer Binders for Alkaline Fuel Cells.

Anion exchange ionomer (AEI) binders are critical to the performance of alkaline electrochemical devices (i.e., fuel cells, electrolyzers, and batteries), as they facilitate ion transport, provide structural integrity, and improve the overall performance and lifespan of these devices. These binders not only ensure ion transport but also provide mechanical stability to the electrode materials. Recently, there has been significant progress in designing AEIs that are more compatible with existing electrode materials and electrolytes. This review summarizes the different types of AEI binders, focusing on their chemical structure, functionalization, conductivity, and how they affect the performance of alkaline fuel cells, specifically, anion exchange membrane fuel cells (AEMFCs). It also discusses how factors like functional groups, polymer backbone and side-chain flexibility, and ion exchange capacity balance conductivity, mechanical strength, and water uptake (WU). Recent advances in material design, such as polymer blends, composites, and crosslinked ionomers, as well as electrode setup, such as asymmetric ionomer electrodes, are explored as methods for improving stability and ion transport. The main challenges facing AEIs, including water management, alkaline degradation, phase separation, mechanical robustness, and long-term durability, are discussed along with strategies for overcoming them. Finally, we outline future research directions for developing scalable, economical solutions and integrating these binders with new electrode materials to help improve the performance and stability of next-generation AEMFCs.