Experimental and theoretical investigations of transport processes in polymer electrolyte fuel cells

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Canada's current fossil fuelled transportation sector consumes nearly 30% of our primary energy. Polymer electrolyte fuel cells (PEFCs) and batteries present viable alternatives to replace the current transportation energy system. Hydrogen, produced by water splitting in a polymer electrolyte electrolyzer (PEE) using electricity from renewable energy sources, could be used in PEFCs to power a vehicle. PEFCs produce only water vapor thereby eliminating pollution and greenhouse gas emissions. PEFC vehicles have demonstrated all the attributes that customers expect such as quick start-up and refuelling, long range, and durability. Prerequisites for an increase in market penetration of PEE, and PEFC vehicles, are production cost reductions as well as performance and durability improvements. In order to reduce the cost of PEFCs and PEEs to commercialization targets, i.e., $30/kW and $300/kW respectively (2020 U.S. Department of Energy targets), it is necessary to improve mass transport in the electrode in order to enable higher power density operation and the use of less precious catalysts. Due to the complex materials and physical phenomena, numerical modelling is required for PEFC and PEE analysis and design. Remarkable progress has been achieved in macroscale numerical modelling of fuel cells and electrolyzers. These models however cannot account for how microscopic features in the porous composite materials in PEFCs and PEEs affect mass transport properties and reactions. Nanometer scale imaging combined with statistical analysis, reconstruction, and simulation should be used to account for these effects. At high current density, liquid water accumulation in the electrode also reduces transport to the reaction site, thereby limiting the fuel cell maximum power. Water accumulation can be minimized by designing better transport layers using micro-fabrication techniques such as inkjet printing. The issues above, degradation, and material research are critical to PEFCs and PEEs. The proposed Discovery grant program aims at developing: a) micro-scale statistical analysis, reconstruction, and numerical models, and ex-situ experimental tools to study the effect of electrode micro-structures on transport properties and water accumulation; and, b) novel fuel cell architectures that aim at minimizing water accumulation. The focus will be in PEFCs, however, due to the closeness of physical processes, the numerical and experimental tools are also applicable to PEEs. The new numerical models and architectures aim at designing electrodes with increased catalyst utilization and maximum power density which can lead to cheaper and better performing PEFCs. This research will contribute to the Canadian economy by developing fundamental understanding, novel tools, and training HQP to maintain Canada's leadership in fuel cells. My software is already in use at Canadian industries.