Modeling of transient platinum degradation in a low Pt-loading PEFC under current cycling

Pt degradation is one of the most important aging mechanisms that control the lifespan of automotive polymer electrolyte fuel cells (PEFCs). The consequence of Pt degradation is loss of the electrochemical active surface area (ECA) in cathode catalyst layers (CCLs) of PEFCs. The reduction of ECA increases not only the activation overpotential through reducing sites of oxygen reduction reaction (ORR) kinetics but also the mass transport loss through causing an additional micro-scale oxygen transport resistance in the ionomer film surrounding Pt particles. In this study, a 1D physics-based Pt degradation submodel is coupled into the transient M2 model to study the non-uniform Pt degradation and its impacts on long-term PEFC performance. The performance loss of a low Pt-loading PEFC with Pt degradation, the interactions of Pt degradation with the micro-scale transport resistance, the cause and consequence of non-uniform Pt degradation, as well as a strategy of raising lower current density in current cycling test are quantified. This Pt degradation model is demonstrated to be an effective approach to better understand Pt degradation, performance loss caused by Pt degradation, and mitigation strategies to alleviate Pt degradation, all important for achieving excellent durability of PEFCs.