Cold‐Start Capacity Attenuation in 60‐kW PEMFC Systems: A Multiscale Componential Analysis

ABSTRACT By overcoming low‐temperature limitations, it paves the way for widespread commercialization of fuel cells, reinforcing their role in achieving sustainable energy systems and combating climate change. Therefore, this work systematically analyzes the reasons for the degradation of the fuel cell stack after low‐temperature start‐up operation with an effective area of 367 cm 2 and 170 cells. To investigate the root causes, systematic characterization of the catalyst layer (CL) and gas diffusion layer (GDL) was performed. Transmission electron microscopy and x‐ray diffraction analyses confirmed that Pt particles exhibited increased defects and particle size at three membrane electrode positions, particularly at the hydrogen inlet/outlet, where the (111) interplanar spacing expanded significantly. Raman spectroscopy detected carbon corrosion on both anode and cathode sides after cold start, with anode corrosion being more severe. GDL permeability decreased significantly post‐cold start, especially at the hydrogen outlet. Cold‐start‐induced water redistribution promotes ice formation at CL/GDL interfaces, triggering localized reverse polarity. Reverse polarity accelerates carbon corrosion, destabilizing catalyst supports (Pt agglomeration) and GDL pore structure (carbon powder loss). This study elucidates the multiscale degradation mechanisms of membrane electrodes under cold‐start conditions, providing critical insights for improving fuel cell low‐temperature durability.