Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs

Schneider IA, Freunberger SA, Kramer D, Wokaun A, Scherer GG. 2007. Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs. Journal of The Electrochemical Society. 154(4), B383.

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Journal Article | Published | English
Author
Schneider, I. A.; Freunberger, Stefan AlexanderIST Austria ; Kramer, D.; Wokaun, A.; Scherer, G. G.
Abstract
Our experimental results shown here disprove that finite diffusion can generally be assumed in ac impedance models for H2/air-polymer electrolyte fuel cells (PEFCs) to account for the diffusive transport of oxygen through the gas diffusion layer (GDL) toward the air electrode. It is shown that the amplitude of the oxygen concentration oscillation created as a consequence of superimposed ac current at the air electrode is not zero at the channel/GDL interface but extends into the gas channels, at least below modulation frequencies of fmod=10 Hz . By this, sinusoidal oxygen-concentration oscillations within the cathode gas channels are excited locally along the flow field. Due to the forced air convection in the cathode flow-field channels, a coupling via the gas phase occurs downstream of the flow field. The coupling strongly affects the local and by this the overall impedance response of the cell and evokes the formation of a low-frequency arc in H2/air-PEFC impedance spectra. Based on the experimental results, a qualitative model is presented explaining the local impedance response of a segmented 200cm2H2/air PEFC.
Publishing Year
Date Published
2007-02-09
Journal Title
Journal of The Electrochemical Society
Volume
154
Issue
4
Article Number
B383
ISSN
IST-REx-ID

Cite this

Schneider IA, Freunberger SA, Kramer D, Wokaun A, Scherer GG. Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs. Journal of The Electrochemical Society. 2007;154(4). doi:10.1149/1.2435706
Schneider, I. A., Freunberger, S. A., Kramer, D., Wokaun, A., & Scherer, G. G. (2007). Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs. Journal of The Electrochemical Society. The Electrochemical Society. https://doi.org/10.1149/1.2435706
Schneider, I. A., Stefan Alexander Freunberger, D. Kramer, A. Wokaun, and G. G. Scherer. “Oscillations in Gas Channels: Part I. The Forgotten Player in Impedance Spectroscopy in PEFCs.” Journal of The Electrochemical Society. The Electrochemical Society, 2007. https://doi.org/10.1149/1.2435706.
I. A. Schneider, S. A. Freunberger, D. Kramer, A. Wokaun, and G. G. Scherer, “Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs,” Journal of The Electrochemical Society, vol. 154, no. 4. The Electrochemical Society, 2007.
Schneider IA, Freunberger SA, Kramer D, Wokaun A, Scherer GG. 2007. Oscillations in gas channels: Part I. The forgotten player in impedance spectroscopy in PEFCs. Journal of The Electrochemical Society. 154(4), B383.
Schneider, I. A., et al. “Oscillations in Gas Channels: Part I. The Forgotten Player in Impedance Spectroscopy in PEFCs.” Journal of The Electrochemical Society, vol. 154, no. 4, B383, The Electrochemical Society, 2007, doi:10.1149/1.2435706.

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