NaCl-Induced Degradation Mechanism in Membrane-Electrode Assembly for Ship Operation of Proton-Exchange Membrane Fuel Cells

NaCl contamination of membrane-electrode assemblies is a critical challenge for the stability and long-term durability of proton-exchange membrane fuel cells (PEMFCs), particularly in marine and humid environments. In this study, we systematically investigated the degradation behavior of PEMFCs under NaCl exposure by decoupling the individual effects of Na+ and Cl– ions through electrochemical and spectroscopic analyses. Electrochemical impedance spectroscopy revealed that Na+ had a minimal impact on proton conductivity, as evidenced by the stable ohmic resistance over time. In contrast, Cl– significantly increased the charge transfer resistance and decreased the electrochemically active surface area, indicating strong catalyst poisoning. X-ray photoemission spectroscopy analysis showed broadened Pt 4f peaks and the emergence of Pt4+ states, while white X-ray absorption near-edge spectroscopy revealed an increase in the white-line intensity, reflecting the changes in electronic structure at the Pt surface. Transmission electron microscopy further confirmed the Pt nanoparticle growth from 2.4 to 4.0 nm after prolonged operation in both NaCl-free and NaCl-containing cells, which is consistent with Ostwald ripening rather than Cl–-induced dissolution. Collectively, these results demonstrate that Na+ has a limited effect on membrane properties, while Cl– interacts strongly with the catalyst. This study offers a systematic multimodal analysis of salt-induced failure modes in PEMFCs and provides critical insights into their deployment in chloride-rich environments.