Probing the Performance-Degradation Interactions in the PEFC Catalyst Layer

Abstract

Polymer Electrolyte Fuel Cells (PEFC) exhibit considerable performance decay with cycling owing to the degradation of Platinum (Pt) catalysts which results in loss of electrochemically active surface area. Strategies to prevent the Pt inventory loss in the cathode catalyst layer is thus a focal point in ameliorating the life expectancy of the PEFC. In this work, we present a thermo-kinetic model incorporating the various deleterious mechanisms occurring in tandem including Ostwald Ripening on carbon support, oxide coverage over the Pt particles and Pt dissolution, diffusion through the ionomer phase and reprecipitation reaction which is coupled with a microstructure resolved electrochemical performance model. The influence of microstructural features has been investigated to provide detailed insights of the transients of the participating phenomena that contribute to catalyst degradation. In addition to elucidating the spatial heterogeneity of degradation, we also demonstrate a representative temporal scale which is commensurate with the long-term aging behavior.