Durable PEM Fuel Cell Electrode Materials: Requirements and Benchmarking Methodologies

This paper discusses methodologies to evaluate durability of catalyst and carbon-support materials used in Polymer Electrolyte Membrane (PEM) fuel cells under relevant automotive accelerated test conditions. Durability of carbon-supported Pt and Pt-alloy catalyst is evaluated under an accelerated voltage- cycling protocol, developed by analyzing idle-to-peak power load-transients of various automotive drive-cycles. Results indicate that Pt catalysts on conventional carbon supports (Pt/C) are unlikely to meet automotive durability target; however, given no loss in specific-activity over time, Pt- alloys are likely to be successful. Shutdown/startup of fuel cell stack and local fuel starvation are recognized as an accelerating mechanism for carbon-support corrosion. Conventional and corrosion-resistant supports are evaluated under an accelerated protocol (1.2V vs. RHE). Corrosion of these currently used supports induces unacceptable mass- transport related performance loss at high current densities. Implementation of corrosion-resistant supports in high- performance electrodes, combined with controlled system strategies, will most likely lead to automotive carbon support durability targets being met.