Materials and Design Selection to Improve High Current Density Performance in PEMFC

Performance at high current density is dominated by transport losses from resistance to oxygen and proton transport. The materials selection and their properties can have a significant impact on the transport resistance. In this study, the impact of catalyst carbon support microstructure and its properties impacting performance at high current density is studied in detail. Platinum-cobalt alloy catalysts supported on different carbon supports were analyzed for pore size distribution characteristics. Catalyst layer electrochemical diagnostics such as oxygen limiting current and H2/N2 impedance tests were conducted to measure local oxygen transport resistance and bulk proton transport resistance. For the first time, the local-oxygen transport and the bulk-proton transport resistances in the catalyst layer are directly correlated to the micropore and macropore properties of the carbon support.