Degradation of Ionic Pathway in PEM Fuel Cell Cathode
The degradation of the ionic pathway throughout the catalyst layer in proton exchange membrane fuel cells was studied under an accelerated stress test of catalyst support (potential hold at 1.2 V). Electrochemical behaviors of the cathode based on graphitic mesoporous carbon supported Pt catalyst were examined using electrochemical impedance spectroscopy and cyclic voltammetry. Impedance data were plotted and expressed in the complex capacitance form to determine useful parameters in the transmission line model: the double-layer capacitance, peak frequency, and ionic resistance. Electrochemical surface area and hydrogen crossover current through the membrane were estimated from cyclic voltammogram, while cathode Faradaic resistance was compared with ionic resistance as a function of test time. It was observed that during an accelerated stress test of catalyst support, graphitic mesoporous carbon becomes hydrophilic which increases interfacial area between the ionomer and the catalyst up to 100 h. However, the ionic resistance in the catalyst layer drastically increases after 100 h with further carbon support oxidation. The underlying mechanism has been studied and it was found that significant degradation of ionic pathway throughout the catalyst layer due to catalyst support corrosion induces uneven hydration and mechanical stress in the ionomer.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1033838
- Report Number(s):
- PNNL-SA-81432; 40067; EB4209000
- Journal Information:
- Journal of Physical Chemistry C, Journal Name: Journal of Physical Chemistry C Journal Issue: 45 Vol. 115; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
24 POWER TRANSMISSION AND DISTRIBUTION
30 DIRECT ENERGY CONVERSION
CAPACITANCE
CARBON
CATALYST SUPPORTS
CATALYSTS
CATHODES
CORROSION
Environmental Molecular Sciences Laboratory
FUEL CELLS
HYDRATION
HYDROGEN
IMPEDANCE
MEMBRANES
OXIDATION
POWER TRANSMISSION LINES
PROTON EXCHANGE MEMBRANE FUEL CELLS
Proton Exchange Membrane Fuel Cells
SPECTROSCOPY
SURFACE AREA
carbon corrosion
ionic pathway