Asymmetric ionomer configuration in membrane electrode assembly for enhanced water management and performance in anion exchange membrane fuel cells

Abstract

Anion exchange membrane fuel cells (AEMFCs) are considered a more affordable technology compared to proton exchange membrane fuel cells (PEMFCs), but the performance and durability of AEMFCs are still not competent with PEMFCs owing to the more challenging water management, which severely hinders its development and real-life applications. In this study, we introduce the strategy to boost the performance and stability of the membrane electrode assembly (MEA) of AEMFCs by regulating the hydrophilicity of the anode and cathode ionomers. Two poly(biphenyl alkylene) ionomers with different hydrophilicity are synthesized and used to fabricate MEAs with asymmetric or symmetric ionomer configurations in the anodic and cathodic catalyst layers (CLs) for AEMFCs. Molecular dynamics (MD) simulations have revealed different diffusion rates of water in the hydrophobic anode and the hydrophilic cathode, which show the potential of this design to improve water management in AEMFCs. The effectiveness of this design is also confirmed by experimental results that the MEA with this asymmetric configuration exhibits the highest power and current densities of 1.58 W cm⁻² or 5.58 A cm⁻², respectively, among all configurations. Furthermore, this configuration also enhances the durability, with the MEA showing a voltage decay rate of only 313.1 μV h⁻¹ after 500 h of in-situ durability test at 0.2 A cm⁻². This study provides new insights into the rational design of more efficient water management in MEA for high-performance AEMFCs.