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Mitigation of Fuel Cell Degradation Through MEA Design
Abstract:
Hydrogen PEM fuel cells offer a viable way of providing the electrical energy to power a vehicle. With rapid refueling and acceptable range on a tank of fuel, they provide a complementary technology to battery-powered EVs that will ultimately offer a route to decarbonising transport.
However, the demands on an automotive fuel cell stack provide a challenging environment for key components within the membrane electrode assembly (MEA). Frequent start-up shut-down events and freeze starts can create conditions that cause corrosion within the fuel cell. The risk of fuel starvation to individual cells within a large stack of several hundred cells is also a potential cause of corrosion which will inevitably lead to degradation and reduced stack lifetime. While there are system-level mitigation strategies that can be employed in terms of design, controls and interventions, the most efficient solution is to improve the intrinsic stability of the key cell components themselves.
Many of the mechanisms that lead to degradation can be addressed through the design of the MEA. Potential excursions that drive corrosion of cathode catalysts layers have been found, perhaps surprisingly, to be reduced by design changes in the anode catalyst. Anodes can be protected from corrosion caused by cell reversal through the incorporation of additional oxygen evolution reaction functionality built into the catalyst layer. We have demonstrated significant improvements to MEA stability and durability through such design changes. In particular, significant improvements in cell reversal tolerance of MEAs with novel anodes are described.