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Reversible and Irreversible Degradation Phenomena in PEMFCs

Mitzel, Jens and Gazdzicki, Pawel and Biswas, Indro and Schulze, Mathias and Friedrich, K. Andreas (2016) Reversible and Irreversible Degradation Phenomena in PEMFCs. 21st World Hydrogen Energy Conference 2016, 13.-16. Jun. 2016, Zaragoza, Spain.

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The presentation is focused on reversible and irreversible degradation phenomena in polymer electrolyte membrane fuel cells (PEMFCs). Analytical methods for the determination of component degradation will be presented and a new systematic approach for the analysis of reversible and irreversible degradation rates in an operating fuel cell will be introduced. A detailed description of voltage loss rates and particularly of the discrimination between reversible and irreversible voltage losses will be given. A major motivation of the presented work is the lack of common description procedures and determination approaches of voltage losses in durability tests of fuel cell. This issue results in severe difficulties in the comparison of results obtained by different testing facilities or within different research projects especially if only one value for a degradation rate is reported. In order to systematically analyze voltage losses we have performed single cell durability measurements of several hundreds of hours in 25 cm2 lab-scale cells. Specific test protocols containing regular refresh procedures were used for this purpose (see Figure 1). This enables distinguishing between reversible and irreversible voltage losses. To test the refresh procedures and analyze their effect on cell performance, parameters such as the duration of e.g. a soak time step have been varied. Between these refresh steps the cells were typically operated for 50 to 150 h. Conventional 5-layer MEAs with PFSA membranes, carbon supported Pt-catalysts and hydrophobized carbon fiber substrates with micro porous layers as GDLs were used for this study. For in-situ diagnostics of the operated cells polarization curves, impedance spectra, and CVs were recorded in order to determine the impact of the refresh procedures on the cells. Ex-situ methods were used to determine the causes for the reversible and irreversible voltage losses. Using different methods, detailed information about the physical composition of the individual fuel cell components can be obtained in order to optimize them and increase cell durability. Depending on the examined component and the analytical objective infrared absorption spectroscopy (FTIR), Raman, and X-ray photoemission spectroscopy (XPS) can be used to analyze the degradation effects and the sources for reversible and irreversible voltage loss during fuel cell operation. An overview of the different methods and their application will be given. It will be shown, that a combination of complementary methods is necessary to gather a comprehensive view of the occurring processes and mechanisms. As an example, depth profiling techniques combined with XPS can be used to determine the composition changes inside the fuel cell electrodes.

Item URL in elib:https://elib.dlr.de/108073/
Document Type:Conference or Workshop Item (Poster)
Title:Reversible and Irreversible Degradation Phenomena in PEMFCs
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mitzel, JensJens.Mitzel (at) dlr.deUNSPECIFIED
Gazdzicki, Pawelpawel.gazdzicki (at) dlr.deUNSPECIFIED
Biswas, Indroindro.biswas (at) dlr.deUNSPECIFIED
Schulze, Mathiasmathias.schulze (at) dlr.deUNSPECIFIED
Friedrich, K. Andreasandreas.friedrich (at) dlr.deUNSPECIFIED
Date:13 June 2016
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:PEMFC Degradation rates Reversible degradation Irreversible Degradation Analytical methods
Event Title:21st World Hydrogen Energy Conference 2016
Event Location:Zaragoza, Spain
Event Type:international Conference
Event Dates:13.-16. Jun. 2016
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E EV - Energy process technology
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells) (old)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Mitzel, Dr. Jens
Deposited On:22 Nov 2016 09:22
Last Modified:31 Jul 2019 20:05

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