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Study of current distribution and oxygen diffusion in the fuel cell cathode catalyst layer through electrochemical impedance spectroscopy

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journal contribution
posted on 02.10.2012, 11:34 by Samuel Cruz-Manzo, Rui ChenRui Chen, Pratap Rama
In this study, an analysis of the current distribution and oxygen diffusion in the Polymer Electrolyte Fuel Cell (PEFC) Cathode Catalyst Layer (CCL) has been carried out using Electrochemical Impedance Spectroscopy (EIS) measurements. Cathode EIS measurements obtained through a three-electrode configuration in the measurement system are compared with simulated EIS data from a previously validated numerical model, which subsequently allows the diagnostics of spatio-temporal electrochemical performance of the PEFC cathode. The results show that low frequency EIS measurements commonly related to mass transport limitations are attributed to the low oxygen equilibrium concentration in the CCLeGas Diffusion Layer (GDL) interface and the low diffusivity of oxygen through the CCL. Once the electrochemical and diffusion mechanisms of the CCL are calculated from the EIS measurements, a further analysis of the current density and oxygen concentration distributions through the CCL thickness is carried out. The results show that high ionic resistance within the CCL electrolyte skews the current distribution towards the membrane interface. Therefore the same average current density has to be provided by few catalyst sites near the membrane. The increase in ionic resistance results in a poor catalyst utilization through the CCL thickness. The results also show that non-steady oxygen diffusion in the CCL allows equilibrium to be established between the equilibrium oxygen concentration supplied at the GDL boundary and the surface concentration of the oxygen within the CCL. Overall, the study newly demonstrates that the developed technique can be applied to estimate the factors that influence the nature of polarization curves and to reveal the effect of kinetic, ohmic and mass transport mechanisms on current distribution through the thickness of the CCL from experimental EIS measurements.

Funding

The authors thank the Mexican National Council for Science and Technology (CONACYT) for the sponsorship of the Ph.D. research study of S. Cruz-Manzo (Grant no. 183195).

History

School

  • Aeronautical, Automotive, Chemical and Materials Engineering

Department

  • Aeronautical and Automotive Engineering

Citation

CRUZ-MANZO, S., CHEN, R. and RAMA, P., 2013. Study of current distribution and oxygen diffusion in the fuel cell cathode catalyst layer through electrochemical impedance spectroscopy. International Journal of Hydrogen Energy, 38 (3), pp.1702–1713.

Publisher

Elsevier (© Hydrogen Energy Publications, LLC.)

Version

AM (Accepted Manuscript)

Publication date

2013

Notes

This is the author’s version of a work that was accepted for publication in International Journal of Hydrogen Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.ijhydene.2012.08.141. The paper was also presented at 2011 Zing International Hydrogen and Fuel Cells Conference: from Nanomaterials to Demonstrators, December 1-5, Cancun, Mexico.

ISSN

0360-3199

Language

en