{'fraction_non_alphanumeric': 0.01908957415565345, 'fraction_numerical': 0.0007342143906020558, 'mean_word_length': 5.310185185185185, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Degradation Behavior of Membrane in PEFCs under Pressurized Condition

Introduction The degradation of Pt catalyst layer is one of the major degradation problems in polymer electrolyte fuel cells (PEFCs) during operation, especially at the load cycling or open circuit. Cathode Pt dissolves to Pt ions due to load cycling and then two simultaneously occurring processes are possible: (a) growth of Pt particles on the carbon support in the cathode, (b) Pt ion diffusion into the membrane and then Pt precipitation (Pt band) inside the membrane via reaction with H2 permeating through the membrane. Thus the electrochemical surface area (ECA) loss in PEFC cathodes and Pt band inside the electrolyte membrane are caused via these processes, respectively. Moreover, the decomposition of the electrolyte membrane might be also attributed to Pt band. In our previous study, we reported that the amount of the Pt precipitation inside the membrane was increased under the pressurized condition during the load cycling. In this study, we conducted cell voltage cycling tests using different operating pressures. We measured the fluoride ion concentration in the effluent water of the anode and the cathode and calculated the fluoride ion emission rate (FER) in order to investigate membrane degradation behavior during the cycling tests under the pressurized condition.