Numerical framework to study structural wetting properties of proton exchange membrane fuel cell catalyst layers with manufacturing parameters

Understanding how manufacturing parameters affect water transport in Proton Exchange Membrane Fuel Cell (PEMFC) Catalyst Layers (CLs) is important for improving CL design and the predictive capability of cell scale models. However, liquid water distributions in these multicomponent porous structures remain difficult to resolve experimentally. In this work, a computational framework is presented to relate manufacturing inputs, CL microstructure, and two-phase transport properties. A discrete element method is used to generate three-dimensional catalyst-layer microstructures from manufacturing related parameters, and a phase-field lattice Boltzmann model is employed to characterize pore scale two-phase transport with distinct contact angles assigned to ionomer and catalyst surfaces. After verification using standard benchmark tests, the workflow is applied to microstructures generated with different water/isopropanol solvent ratios in the ink composition. Liquid water coverage ratios, relative permeabilities, and capillary pressure curves are quantified and compared. The results indicate that solvent composition has a marked influence on water coverage of the solid phases through its effect on microstructure, whereas invasion behavior is mainly controlled by local wettability. Beyond providing high-resolution insight, this framework also highlights limitations of commonly used macroscopic closure relations and provides a physically grounded route for improved CL optimization and multiscale performance modeling.