Interpreting Ionic Conductivity for Polymer Electrolyte Fuel Cell Catalyst Layers with Electrochemical Impedance Spectroscopy and Transmission Line Modeling
Journal Article
·
· Journal of the Electrochemical Society
- Univ. of California, Irvine, CA (United States)
- Tufts Univ., Medford, MA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Tufts Univ., Medford, MA (United States)
- 3M Company, St. Paul, MN (United States)
- Univ. of California, Irvine, CA (United States); Tufts Univ., Medford, MA (United States)
A cathode catalyst layer containing optimally distributed ionomer is critical to reduce the platinum loading and increase its utilization in polymer electrolyte fuel cells. Here, electrochemical impedance spectroscopy (EIS) was used to measure effective ionic conductivity of pseudo catalyst layers (PCLs) at a relative humidity (RH) range of 50%-120%. These results are compared to previous work using the hydrogen pump (HP) method. EIS effective ionic conductivity results reported here are higher than those from the HP because in the HP set-up ionic pathways must be effectively connected through the PCL to be counted, whereas in the EIS measurement, ionomer segments that are in contact with the membrane but are not effectively connected all the way through the PCL can be detected. Double layer capacitances and effective ionic conductivities of Pt/C catalyst layers with various supports and ionomer to carbon (I/C) ratios were studied. High surface area carbon support resulted in a lower effective ionic conductivity compared to the graphitized carbon support due to worse ionomer dispersion. Effective ionic conductivities of Pt/C layers were compared to that of PCLs. On average, effective ionic conductivities of Pt/C layers were higher than PCLs because of possible carbon agglomeratio n within the PCLs.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-05CH11231; EE0007650
- OSTI ID:
- 1813388
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 5 Vol. 168; ISSN 0013-4651
- Publisher:
- IOP Publishing - The Electrochemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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OSTI ID:1799318