(166a) Importance of Transport in Fuel Cells and Their Components

As electrochemical technologies become increasingly important in our energy paradigm, especially fuel cells, there is a need to examine them holistically. Furthermore, for such technologies to become practical, they need to operate at high current densities to minimize various cell costs. This operating space necessitates the need for efficient transport of reactants and removal of products from the reaction site and in a solid-state architecture that utilizes ion-conducting polymers (ionomers). In this talk, we will explore the various tradeoffs endemic in such gas-diffusion electrode (GDE) architectures undergoing fuel-cell reactions. We will examine the major phenomena within fuel cells with a focus on water management, as well as examine changes that occur during operation (e.g., increased wettability, catalyst particle growth) that exaggerate the local transport limitations. Such tradeoffs are quantified through multiphysics modeling and key diagnostics of the cells and components including breakdowns of the various limiting phenomena and properties at both the micro and macroscales, where the local conditions and environment around the reaction site impact reactivity. In addition, we will take a deeper examination into the transport processes within the ionomer itself. While an ideal ionomer in many different technologies is a solid-state single-ion conductor, this is rarely seen in practice where other ions may exist as contaminants, additives, or due to electrolyte solutions. We will examine these various tradeoffs and their impacts on properties, water transport, and eventually overall cell performance.