Spatially and temporally resolved stainless steel bipolar plate degradation model for PEMFCs

Predicting multilayer oxide growth on stainless-steel bipolar plates (BPPs) in proton exchange membrane fuel cells (PEMFCs) remains challenging because of the complex interplay between electrochemical and transport processes. To address this challenge, we present a BPP degradation model that accounts for the competitive growth of chromium and iron oxide layers and couple it with a real-time-capable, multi-scale, physics-based PEMFC performance model. The results demonstrate that the proposed framework reproduces experimentally observed oxide-thickness evolution and final composition from ToF-SIMS depth profiling with monolayer-level agreement within the uncertainty of the reconstructed literature dataset, while capturing oxygen-vacancy generation, diffusion, and annihilation across the multilayer passive film. Furthermore, the coupled framework enables real-time prediction of spatially non-uniform oxide growth under realistic PEMFC operating conditions, revealing a strong dependence of corrosion dynamics on local cell conditions. The developed framework therefore supports mechanistic interpretation of BPP degradation and provides a basis for future model-based monitoring of stainless-steel BPP degradation in PEMFC systems.