期刊
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
卷 166, 期 16, 页码 F1337-F1343出版社
ELECTROCHEMICAL SOC INC
DOI: 10.1149/2.0671916jes
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-
资金
- U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy [DE-EE0007271]
We characterized the effects of cobalt (Co2+) and other cation contaminants on the oxygen (O-2) transport properties of the PFSA ionomer used in polymer electrolyte membrane fuel cells (PEMFCs) and gained insight into the mechanisms by which contaminant cations inhibit O-2 transport. Such cations can be released by alloy catalysts and environmental conditions and pose a significant challenge to maintaining high current density performance with low platinum (Pt) loadings. We used a test cell capable of isolating the ionomer from the membrane electrode assembly (MEA), allowing for O-2 transport resistance (RO2) measurements using a limiting current technique. We contaminated ionomer membranes with Li+, Na+, Ni2+, Co2+, and Ce3+ and found a general increase in RO2 for increased contamination levels and decreased water activity. In addition, our Co2+ results indicated distinct concentrationdependent regimes. The other cation-form ionomers allowed us to separate the impacts of ion pair strength, multivalency, and reduced water uptake. We believe that these factors cause a more compressed hydrophilic domain and tortuous O-2 diffusion path, and a commensurate increase in RO2. Finally, we studied the impact of Co2+ on an operating PEMFC and found an increase in RO2 consistent with the results of our isolated membrane tests. (C) 2019 The Electrochemical Society.
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