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Model-based analysis of Electrochemical Pressure Impedance Spectroscopy (EPIS) for PEM Fuel Cells

  • Electrochemical impedance spectroscopy (EIS) is a widely-used diagnostic technique to characterize electrochemical processes. It is based on the dynamic analysis of two electrical observables, that is, current and voltage. Electrochemical cells with gaseous reactants or products, in particular fuel cells, offer an additional observable, that is, the gas pressure. The dynamic coupling of current orElectrochemical impedance spectroscopy (EIS) is a widely-used diagnostic technique to characterize electrochemical processes. It is based on the dynamic analysis of two electrical observables, that is, current and voltage. Electrochemical cells with gaseous reactants or products, in particular fuel cells, offer an additional observable, that is, the gas pressure. The dynamic coupling of current or voltage with gas pressure gives rise to a number of additional impedance definitions, for which we have previously introduced the term electrochemical pressure impedance spectroscopy (EPIS) [1,2]. EPIS shows a particular sensitivity towards transport processes of gas-phase or dissolved species, in particular, diffusion coefficients and transport pathway lengths. It is as such complementary to standard EIS, which is mainly sensitive towards electrochemical processes. First EPIS experiments on PEM fuel cells have recently been shown [3]. We present a detailed modeling and simulation analysis of EPIS of a PEM fuel cell. We use a 1D+1D continuum model of a fuel/air channel pair with GDL and MEA. Backpressure is dynamically varied, and the resulting simulated oscillation in cell voltage is evaluated to yield the ▁Z_( V⁄p_ca ) EPIS signal. Results are obtained for different transport situations of the fuel cell, giving rise to very complex EPIS shapes in the Nyquist plot. This complexity shows the necessity of model-based interpretation of the complex EPIS shapes. Based on the simulation results, specific features in the EPIS spectra can be assigned to different transport domains (gas channel, GDL, membrane water transport).show moreshow less

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Metadaten
Author:Lutz Schiffer, Wolfgang G. BesslerORCiDGND, Daniel Grübl
Contributing Corporation:European Fuel Cell Forum AG
Place of publication:Luzern
Year of Publication:2019
Pagenumber:8
ISBN:978-3-905592-24-5
Language:English
Parent Title (English):Proceedings EFCF 2019 - Low-Temperature Fuel Cells, Electrolysers & H2 Processing
First Page:70
Last Page:77
Document Type:Conference Proceeding
Institutes:Hochschule Offenburg / Bibliografie
Acces Right:Zugriffsbeschränkt
Release Date:2020/01/13
Licence (German):License LogoEs gilt das UrhG
Note:
23th European Fuel Cell Forum – EFCF 2019, Luzern, Schweiz, 02.-05. Jul. 2019