Effects of Cobalt Cation on Low Pt-loaded PEM Fuel Cell Performance

Pt alloys such as PtCo are attractive as cathode catalysts in PEM fuel cell systems due to their high catalytic activities. However, in a fuel cell the non-noble metal such as cobalt can dissolve and not only cause degradation of oxygen reduction activity but can also migrate into the ionomer inducing proton conduction loss, especially at high current densities. These losses are not readily explained quantitatively using our current fuel cell model. In this study, we conducted controlled experiments where known amounts of Co cation were exchanged into membrane-electrode assemblies (MEAs). The effects of Co level on oxygen reduction activity, electrode and membrane proton conductions, and electrode oxygen transport were studied using multiple electrochemical methods on MEAs. These newly acquired results will be used to improve our current model and provide direction for future fuel cell development.