Asymmetric Electrode Ionomers Based on Polydiallyldimethylammonium Block Copolymers for Enhanced Performance in Anion Exchange Membrane Fuel Cells

Fuel cells offer a promising solution for clean energy conversion, with anion exchange membrane fuel cells (AEMFCs) being particularly attractive for their potential to use less expensive, non-platinum group metal (non-PGM) catalysts. Despite significant progress in AEMFCs in recent years, their performance is limited by instability often resulting from water imbalance within the cell (e.g, anode flooding, cathode dry-out). Implementing asymmetric electrode anion exchange ionomers (AEIs), i.e., using a hydrophobic AEI at the anode to inhibit swelling and a hydrophilic AEI at the cathode to prevent water depletion, could overcome issues of poor water management. In this study, block copolymer (BCP) AEIs of polydiallyldimethylammonium hydroxide- block -polystyrene (PDADMAOH- b -PS) were synthesized via reversible addition-fragmentation chain transfer polymerization, achieving ion exchange capacities of 1.03 to 3.40 mmol g −1 . These BCP AEIs were employed in the AEMFCs to optimize water distribution by controlling the hydrophobicity/hydrophilicity of the gas diffusion layers. Our results demonstrated lower ohmic losses and mass transport limitations in the asymmetric electrode design vs the symmetric analog.