Hubert A. Gasteiger

The Impact of Carbon Stability on PEM Fuel Cell Startup and Shutdown Voltage Degradation

Conventional carbon MEAs and graphitized carbon MEAs were evaluated for the resistance to carbon corrosion and startup/shutdown durability in this paper. Graphitized carbon MEAs show higher resistance to carbon corrosion than conventional carbon MEAs by a factor of 35 at a point where 5% weight loss had occurred. A graphitized carbon MEA yielded lower degradation rate than that of a conventional carbon MEA by a factor of 5 after 1,000 startup/shutdown cycles. The kinetics of carbon corrosion over both conventional carbon MEAs and graphitized carbon MEAs were measured, and carbon corrosion during startup/shutdown was explained and modeled. The model results correlate to what we have measured from our startup/shutdown durability test. Overall, MEAs with corrosion resistant carbon supports are one of major materials approaches to mitigate cell voltage degradation due to fuel cell startup/shutdown. We believe that a combination of corrosion resistant materials and system operating mitigation strategies is the path to attain the strict automotive durability targets.

Catalyst Development Needs and Pathways for Automotive PEM Fuel Cells

Mass production of fuel cell light-duty vehicles at competitive cost requires cathode (oxygen reduction reaction [ORR]) kinetic mass activities 4-fold higher than those of current state-of-the-art platinum / carbon black catalysts. 1 A catalyst-related cell voltage loss less than 50 mV over the entire current density range is sought over a >10 year automotive lifetime including ~300,000 large load cycles and ~30,000 start-stop cycles. While the materials set used in current demonstration vehicles falls short of these goals, pathways to these challenging targets are visible via increased attention to the structural details of Pt-containing multicomponent catalysts and through development of catalyst and support as a single system.