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High-Resolution Analysis of Ionomer Loss in Catalytic Layers after Operation

Morawietz, Tobias and Handl, Michael and Oldani, Claudio and Gazdzicki, Pawel and Hunger, Jürgen and Wilhelm, Florian and Blake, John and Friedrich, Kaspar Andreas and Hiesgen, Renate (2018) High-Resolution Analysis of Ionomer Loss in Catalytic Layers after Operation. Journal of The Electrochemical Society, 165, F3139-F3147. Electrochemical Society, Inc.. DOI: 10.1149/2.0151806jes ISSN 0013-4651

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Official URL: http://jes.ecsdl.org/content/165/6/F3139

Abstract

The function of catalytic layers in fuel cells and electrolyzers depends on the properties of the ionically conductive phase, which are most commonly perfluorinated ionomers based on Nafion and Aquivion. An analysis by atomic force microscopy reveals that the ultrathin ionomer films around Pt/C agglomerates have a thickness distribution ranging from 3.5 nm to 20 nm. Their conductivity and gas permeation properties determine the fuel cell performance to a large extend. For electrodes in Aquivion-based membraneelectrode-assemblies operation-induced structure changes were investigated by means of material- and conductivity-sensitive atomic force microscopy, infrared spectroscopy and electron-dispersive X-ray analysis. The observed thinning of the ultrathin ionomer films was mainly caused by polymer degradation deduced from reduced swelling after long-time operation and a significant loss of ionomer with operation time detected by infrared spectroscopy. From the linear thickness increase of the ultrathin films with rising humidity, a mainly layered structure of the ionomer was deduced. An influence of thickness of such ultrathin ionomer films on fuel cell lifetime was found by analysis of differently prepared membrane-electrode-assemblies, where a linear increase of irreversible degradation rate with ionomer film thickness in the electrodes of unused membrane-electrode-assemblies was found.

Item URL in elib:https://elib.dlr.de/124466/
Document Type:Article
Title:High-Resolution Analysis of Ionomer Loss in Catalytic Layers after Operation
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Morawietz, TobiasHochschule EsslingenUNSPECIFIED
Handl, MichaelHochschule EsslingenUNSPECIFIED
Oldani, ClaudioSolvay Specialty PolymersUNSPECIFIED
Gazdzicki, PawelPawel.Gazdzicki (at) dlr.dehttps://orcid.org/0000-0002-5728-7861
Hunger, JürgenZSWUNSPECIFIED
Wilhelm, FlorianZSW-BW, GermanyUNSPECIFIED
Blake, JohnJohnson MattheyUNSPECIFIED
Friedrich, Kaspar AndreasAndreas.Friedrich (at) dlr.deUNSPECIFIED
Hiesgen, Renaterenate.hiesgen (at) hs-esslingen.deUNSPECIFIED
Date:March 2018
Journal or Publication Title:Journal of The Electrochemical Society
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:165
DOI :10.1149/2.0151806jes
Page Range:F3139-F3147
Publisher:Electrochemical Society, Inc.
ISSN:0013-4651
Status:Published
Keywords:Polymer membrane fuel cells, Degradation, microstructure
HGF - Research field:Energy
HGF - Program:Storage and Cross-linked Infrastructures
HGF - Program Themes:Fuel cells
DLR - Research area:Energy
DLR - Program:E SP - Energy Storage
DLR - Research theme (Project):E - Electrochemical Processes (Fuel Cells)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Friedrich, Prof.Dr. Kaspar Andreas
Deposited On:20 Dec 2018 13:52
Last Modified:14 Apr 2019 13:40

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