Physics-based prediction of the impact of electrocatalyst degradation and radical scavenger transport on PEM fuel cell performance under real-world driving cycle ageing

Polymer electrolyte membrane fuel cells (PEMFCs) are a promising technology for decarbonizing the transportation sector. However, stack component degradation and the resulting performance ageing remain major barriers to large-scale commercialization. Reliable state-of-health assessment is essential to support the development of durability-oriented control and operation strategies. In this work, a modelling framework coupling a semi-empirical electrocatalyst degradation model, a 1 + 1D physics-based PEMFC performance model, and a 1D in-plane Ce transport model is developed and validated against automotive-representative experimental data. A key innovation is a methodology that converts dynamic voltage profiles into an equivalent sequence of square-wave cycles, enabling the direct application of degradation laws derived from accelerated stress tests to realistic driving conditions. The degradation model accounts for the effects of relative humidity, temperature, upper potential limit, dwell time, and low-voltage excursions on electrochemically active surface area (ECSA) loss. Coupled with the PEMFC model, the framework predicts the heterogeneous ECSA loss in a segmented cell after 1000 h of the automotive ID-FAST driving cycle, which increases from air inlet to air outlet. The average normalized ECSA at end of life is 0.62. The experimentally observed heterogeneous performance ageing, however, is mainly attributed to in-plane Ce redistribution, which accumulates at the air inlet hindering both proton and oxygen transport. After 1000 h, efficiency decreases by 4.5% and 7.5% under low-power and high-power operating modes of the ID-FAST cycle, respectively. The proposed model framework therefore represents a valuable tool for PEMFC durability assessment and state-of-health monitoring under realistic automotive operating conditions.