Polymer Electrolyte Fuel Cell Degradation through Foreign Cation Contamination, Proton Depletion and Carbon Corrosion

The influence of foreign cationic contamination on the thinning of the cathode catalyst layer during non-accelerated testing is explored. Long duration (400 hours) testing was conducted using commercial catalyst coated membranes (CCMs) which showed significant catalyst layer thinning and sharp decrease in performance in a calcium cation contaminated cell. This thinning of the cathode catalyst layer was not observed in a non-contaminated baseline cell. A numerical model was employed to show the foreign cation redistribution during testing, which shows proton depletion in the cathode catalyst layer when the CCM is contaminated with foreign cations. We hypothesize that this lack of protons leads to accelerated carbon corrosion in the cathode to supply protons to oxygen reduction where foreign cations block transport of protons. The transient model is found to under predict the time for cation redistribution, which may be due to lack of accurate of physical and transport parameters.