A multi-scale model for PEMFC performance degradation coupled with catalyst layer microstructure evolution

The accelerated degradation of the cathode catalyst layer (CCL) under dynamic operating conditions is a primary factor limiting the durability of proton exchange membrane fuel cells (PEMFCs). However, the coupled feedback mechanisms between microscopic structural evolution and macroscopic performance remain insufficiently understood. In this study, a dual-scale coupled model was developed, integrating a 1D CCL degradation model with a 3D PEMFC multiphysics performance model to quantitatively describe the structural evolution and its subsequent impact on cell performance under voltage cycling. At the microscopic scale, the 1D model accounts for critical degradation processes, including platinum oxidation, dissolution, Ostwald ripening, and carbon corrosion. At the macroscopic scale, the model couples multi-component gas transport, electrochemical reactions, and electronic/protonic conduction. Based on this model, the effects of operating conditions and CCL structural parameters on performance degradation were systematically analyzed. The results indicate that 80°C is the optimal temperature to balance reaction kinetics with microstructural stability. The upper potential limit (UPL) exerts a decisive influence on cell lifetime; elevating the UPL to 1.1 V exacerbates platinum dissolution and redeposition, thereby accelerating performance decay. Furthermore, low platinum loading intensifies mass transport polarization, particularly in the high-current-density region, where non-uniform degradation of the local microstructure leads to more severe performance losses. This study elucidates the degradation mechanisms under multiphysics fields, providing a theoretical foundation for optimizing CCL design and extending the operational lifetime of PEMFCs.