Modelling of PEMFC Catalyst Layer Mass Transport and Electro-Chemical Reactions Using Multi-scale Simulations

Abstract

The focus of this work is on improving understanding of mass transport limiting phenomena occurring within the micro-structure of Polymer Electrolyte Fuel Cell (PEFC) Catalyst Layers (CL). Micro-scale models, namely agglomerates, are employed within multi-scale CL framework, to examine many phenomena, such as the conductivity of protons in Nafion ionomer, non homogeneous catalyst distributions, oxygen dissolution in ionomer thin films, polydisperse agglomerate structures, and proton transport mechanisms within water filled carbon porous media. Catalyst distribution within CL micro structures, oxygen dissolution in Nafion described as a non-equilibrium process, and the mechanism by which protons are transported within water filled carbon pores are all found to be significant and potential explanations for PEMFC mass transport limited behaviour. The developed simulation framework presented in this work, as part of OpenFCST, the Open source Fuel Cell Simulations Toolbox, can be used in conjunction with experimental methods to improve understanding of said phenomena, improving understanding and design of PEMFCs.