Heterogeneous pore-scale model analysis of micro-patterned PEMFC cathodes

Polymer electrolyte membrane fuel cells (PEMFCs) are a key feature of future hydrogen-based societies. The surface-patterning method for electrolyte membranes has been proposed as a performance improvement technique for PEMFCs. However, its underlying mechanism remains unclear because of complicated mass transport and chemical reaction phenomena. In this study, the surface patterning of a PEMFC cathode was simulated using a unique simulation method of a heterogeneous pore-scale model. The simulation was validated by a comparison of the calculated results with experimental measurements. The model was subsequently applied to investigate variations in the pattern aspect, Pt loading, and ionomer amount and to conduct an advanced pillar structural analysis. A series of numerical simulations suggested that the performance improvement from surface patterning is based on improved proton conduction through the catalyst layer resulting from shortened paths through a tortuous ionomer. Additionally, surface patterning potentially promotes oxygen diffusion by reducing the amount of ionomer and taking advantage of improved proton conduction.