The features of a direct methanol fuel cell cathode impedance due to methanol crossover: Modeling and experiment

We report a model for impedance of the cathode catalyst layer (CCL) of a DMFC. The model employs a non-Tafel rate of the methanol oxidation reaction (MOR) in the cathode and it takes into account diffusive transport of oxygen and methanol. Due to large MOR overpotential on the cathode side, the rate...

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Bibliographic Details
Published in:Electrochimica acta 2013-10, Vol.108, p.376-383
Main Authors: Kulikovsky, A.A., Löhmer, A., Wippermann, K.
Format: Article
Language:English
Subjects:
Catalysts
Cathodes
Diffusion
DMFC cathode
Impedance
Mathematical models
Methanol crossover
Methyl alcohol
Spectra
Surface chemistry
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Summary:We report a model for impedance of the cathode catalyst layer (CCL) of a DMFC. The model employs a non-Tafel rate of the methanol oxidation reaction (MOR) in the cathode and it takes into account diffusive transport of oxygen and methanol. Due to large MOR overpotential on the cathode side, the rate of this reaction is determined by the potential-independent methanol adsorption on the catalyst surface. According to the model, at all methanol concentrations, the presence of methanol in the CCL affects the low-frequency part of the spectrum. In addition, at high methanol concentration, a MOR-dominated domain (virtual anode) forms at the membrane interface. This domain manifests itself as a weakly pronounced second high-frequency arc. The model predictions are compared to the measured in-house and literature cathode spectra.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2013.05.125