Tuning MPL Intrusion to Increase Oxygen Transport in Dry and Partially Saturated Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

Pore network modelling was utilized to simulate oxygen transport behavior and water saturation within stochastically generated gas diffusion layers (GDLs) at various liquid water inlet coverages of the GDL/catalyst layer interface. This study demonstrates that when the GDL is invaded by liquid water through cracks in the microporous layer (MPL), a deeply intruded MPL leads to lower breakthrough saturation for all liquid water inlet coverages ranging from 7% to 80%. Furthermore, a deeply intruded MPL shifts the peak liquid water saturation away from the catalyst layer, reduces the in-plane coverage of water, and reduces the tortuosity of the liquid water pathways. Under dry conditions, the oxygen diffusion coefficient was found to linearly decrease as a function of the MPL intrusion depth into the GDL. Under partially saturated conditions, increasing MPL intrusion depth has a beneficial effect on oxygen transport. The beneficial impact of increasing MPL intrusion depth on oxygen transport increases at higher inlet coverages.