MODELING OXYGEN TRANSPORT IN CARBON SUPPORT MICROSTRUCTURE OF PROTON EXCHANGE MEMBRANE FUEL CELL ELECTRODES USING PORE NETWORKS

Abstract

The structural morphology of high surface area carbon (HSC) on which both the platinum catalyst and ionomer are dispersed is very complex and critical for understanding the transport of oxygen (O<inf>2</inf>). This study aims to develop a model to simulate O<inf>2</inf> transport in the cathode catalyst layer of proton exchange membrane fuel cells fabricated using HSCs. A stochastic two-dimensional multiscale domain, including micro and mesopores, and connecting throats is constructed. Steady state coupled transport and electrochemical reaction models are then implemented into using transport properties estimated using in-house atomistic level calculations. This study provides a multi-scale approach by relating the pore-scale approach with the atomistic level model, allowing to represent a large modeling domain at higher detail. Oxygen concentration in HSC surfaces is predicted for dry and flooded cases. Results show an effective diffusivity of 8.752·10-8 m2/s and 4.851·10-8 m2/s for the flooded case and non-flooded case, respectively. Oxygen concentration drops significantly when micropores are flooded, consequently Pt utilization decreases. © 2023 Elsevier B.V., All rights reserved.