Transport Phenomena in Fuel Cells

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Fuel cells are electrochemical energy conversion devices that offer the prospect of efficient, low to zero emission power for vehicles, homes and portable electronics. The long-term objectives of the proposed research are to facilitate the commercial deployment of polymer electrolyte membrane (PEM) fuel cells by lowering performance and cost barriers.****We propose to measure, model and predict the transfer process of reactant gases, heat, mass, water, electrical and protonic charge—collectively known as transport phenomena—that are central to the performance and cost of PEM fuel cells. These transport phenomena and the electrochemical energy conversion that generates power take place in the membrane-electrode assembly (MEA). The MEA is a thin multilayered structure consisting of a PEM sandwiched between three distinct porous layers: a nanostructured composite catalyst layer; a micro-porous layer; and a fibrous gas diffusion layer. Many of the limitations of current technology are associated with the lack of fundamental understanding of the transport processes and of their relationship to the structure and morphology of the MEA porous layers. ***In the first axis of this multi-pronged research program we will use a combination of tomographic imaging, numerical reconstruction and advanced computational modelling to resolve transport phenomena, including dynamic liquid water transport, within the nanostructure of the fuel cell porous media. This will provide critical information on the effectiveness of the transport processes and their relationship to the nanostructure of the porous layers and to the interfaces between them. ***The second axis will addresses the question of how to eventually control the fabrication process to realize such designs/structures. Catalyst layers are fabricated by depositing and drying an “ink” consisting of suspended particles that tend to agglomerate. We will chart new directions with simulations and novel microscopic visualization of the process to shed light on the fabrication process which to date has evolved by trial and error. ***The third axis will synthesize fundamental insights, observations and models to a) explore functionalized porous media that optimize transport and catalyst utilization; and b) develop a bipolar membrane fuel cell that combines an acidic PEM on the anode with an alkaline anion exchange membrane and which allows self-humidified operation that minimizes losses, as well as use of less expensive non-precious metal catalysts. ***This program addresses pacing issue in the commercialization of fuel cells; furthers the boundaries of knowledge in transport phenomena relevant to a wide range of applications, including batteries, water filtration, and geological carbon sequestration; and provides exciting opportunities for training highly qualified personnel in areas of critical importance to the Canadian clean energy sector. ********