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Impact of inhomogeneous catalyst layer properties on impedance spectra of polymer electrolyte membrane fuel cells

 
: Gerteisen, D.

:

Journal of the Electrochemical Society 162 (2015), No.14, pp.F1431-F1438
ISSN: 0013-4651
ISSN: 1945-7111
ISSN: 0096-4786
English
Journal Article
Fraunhofer ISE ()
Energietechnik; Wasserstoff- und Brennstoffzellentechnologie; Brennstoffzellensysteme; impedance spectroscopy; inhomogeneous catalyst layer property; modeling

Abstract
A physically-based 1D impedance model of the cathode catalyst layer that accounts for inhomogeneous catalyst layer (CL) properties is developed. The impact of locally changing proton conductivity, volumetric double-layer capacity, ORR rate and effective porosity on the characteristics of impedance spectra is analyzed. It was found that a non-constant conductivity and capacity profile within the CL results in a specific fingerprint in the high frequency range of the spectra where at homogeneous conditions a linear 45° branch would be expected. Furthermore, a well pronounced splitting of a high and low frequency loop can be provoked by introducing non-uniformly distributed CL properties. The simulation results show that electrochemical impedance spectroscopy is a valuable tool to investigate the inhomogeneity of the catalyst layer originated by the electrode preparation itself or by degradation processes.

: http://publica.fraunhofer.de/documents/N-366877.html