Abstract
To clarify the degradation mechanism of the perfluorinated polymer electrolytes in polymer electrolyte fuel cells, we studied the decomposition process of the end group of these polymers using the first-principles molecular dynamics method. We successfully clarified that the polymer end model of CF_3CF_2CF_2OH reacts with a hydroxyl radical to generate a water molecule and CF_2O. After CF_2O was desorbed, polymer end model became CF_3CF_2・. CF_3CF_2・reacts with another hydroxyl radical to reproduce the hydroxyl end group. Therefore, it was revealed that cyclic degradation reactions like the unzipping mechanism occur when CF_3CF_2CF_2OH reacts with hydroxyl radicals. Furthermore, it was revealed that the CF_2O desorption reaction is inhibited by surrounding water molecules, while the HF desorption reaction from CF_3CF_2CF_2OH is promoted.
