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Electrochemical diffusimetry of fuel cell gas diffusion layers

Kramer, Denis, Freunberger, Stefan A., Flückiger, Reto, Schneider, Ingo A., Wokaun, Alexander, Büchi, Felix N. and Scherer, Günther G. (2008) Electrochemical diffusimetry of fuel cell gas diffusion layers Journal of Electroanalytical Chemistry, 612, (1), pp. 63-77. (doi:10.1016/j.jelechem.2007.09.014).

Record type: Article

Abstract

The gas diffusion layers (GDLs) of a membrane electrode assembly (MEA) serve as link between flow field and porous electrode within a polymer electrolyte fuel cell. Beside ensuring sufficient electrical and thermal contact between the whole electrode area and the flow field, these typically 200–400 lm thick porous structures enable the access of educts to the electrode area which would be occluded by the flow field lands if the flow field is directly attached to the electrode. Hence, the characterisation of properties pertaining to mass transport of educts and products through these structures is indispensable whilst examining the contribution of the GDLs to the overall electrochemical characteristics of a MEA. A fast and cost effective method to measure the effective diffusivity of a GDL is pre- sented. Electrochemical impedance spectroscopy is applied to measure the effective ionic conductivity of an electrolyte-soaked GDL. Taking advantage of the analogy between Ficks and Ohms law, this provides a measure for the effective diffusivity. The method is described in detail, including experimental as well as theoretical aspects, and selected results, highlighting the anisotropy and dependence on the degree of compression, are shown. Moreover, a two-dimensional model consisting of regularly spaced ellipses is developed to rep- resent the porous structure of the GDL, and by using conformal maps, the agreement between this model and experiment with respect to the sensitivity of the effective diffusivity towards compression is shown.

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More information

Published date: January 2008
Keywords: diffusivity, pefc, tortuosity, electrochemical impedance spectroscopy, electrochemical diffusimetry
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 189735
URI: http://eprints.soton.ac.uk/id/eprint/189735
ISSN: 1572-6657
PURE UUID: d6000015-32ad-4386-a50d-ccb5d00464df

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Date deposited: 06 Jun 2011 13:47
Last modified: 18 Jul 2017 11:40

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Contributors

Author: Denis Kramer
Author: Stefan A. Freunberger
Author: Reto Flückiger
Author: Ingo A. Schneider
Author: Alexander Wokaun
Author: Felix N. Büchi
Author: Günther G. Scherer

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