Effects of Cracks on the Mass Transfer of Polymer Electrolyte Membrane Fuel Cell with High Performance Membrane Electrode Assembly

Abstract

A two-dimensional geometric model is developed for a polymer electrolyte based on the liquid water penetration mechanism in the membrane electrode assemblies under the action of capillary pressure. The effects of the diameter, number, and distribution of cracks in the micro-pore layers (MPLs) of the modeled MEA on the performance of the PEMFC are simulated to investigate the influence of mass transfer across the membrane. The results indicate that liquid water in the catalyst layer (CL) of the MEA can be discharged to gas channels through the cracks in MEA under the action of capillary pressure, thereby alleviating the flooding in the CL and enhancing the diffusion of oxygen to the CL. When the proportion of the total area of cracks in the active area of the MEA was 8%–12%, crack diameter was 20–30 µm, and cracks were distributed uniformly. MEAs with and without cracks were prepared, fuel cells were assembled, and their performance was measured. The effects of cracks on mass transfer were then verified. This study helps prepare MEAs with controllable cracks.

Keywords

PEMFC / MEA / cracking / liquid saturation / oxygen concentration / transfer

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