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Influence of Water and Temperature on Ionomer in Catalytic Layers and Membranes of Fuel Cells and Electrolyzers Evaluated by AFM

Morawietz, Tobias and Handl, Michael and Oldani, Claudio and Friedrich, Kaspar Andreas and Hiesgen, Renate (2018) Influence of Water and Temperature on Ionomer in Catalytic Layers and Membranes of Fuel Cells and Electrolyzers Evaluated by AFM. Fuel Cells, 18 (3), pp. 239-250. Wiley. DOI: 10.1002/fuce.201700113 ISSN 1615-6846

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Abstract

The major difference for the durability of the materials in PEM fuel cells and PEM electrolyzers is the exposure to humidified gases and to liquid water, respectively. Aquivion and Nafion ionomer was investigated at surfaces of membranes and cross-sections of electrodes by material-sensitive atomic force microscopy. The dimensional behavior of electrodes and membranes in a membrane-electrode assembly cross section was studied as a function of combined humidity and temperature changes. The observed opposite effects of ionomer dimensional changes in membrane and catalytic layers are important for understanding mechanical stress factors and degradation. For the lamellar polymer phase at moderate humidity, a linear swelling behavior and the enclosure of multiples of 0.8 nm-thick water layers was observed. Submersed in water, 3 nm-thick enclosed water layers were found. At the water-immersed Aquivion membrane derived from alcoholic dispersion larger 30–50 nm sized water-rich areas were found. In contrast, for membranes derived from water-based dispersion the water-rich phase was smaller with 11 nm. The thickness of the ultrathin ionomer layers in the electrode was investigated as a function of humidity and temperature. A linear swelling was found for humidity changes whereas nonlinear behavior with 100% expansion and hysteresis was seen for temperature cycles.

Item URL in elib:https://elib.dlr.de/124460/
Document Type:Article
Title:Influence of Water and Temperature on Ionomer in Catalytic Layers and Membranes of Fuel Cells and Electrolyzers Evaluated by AFM
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Morawietz, TobiasHochschule EsslingenUNSPECIFIED
Handl, MichaelHochschule EsslingenUNSPECIFIED
Oldani, ClaudioSolvay Specialty PolymersUNSPECIFIED
Friedrich, Kaspar AndreasAndreas.Friedrich (at) dlr.deUNSPECIFIED
Hiesgen, Renaterenate.hiesgen (at) hs-esslingen.deUNSPECIFIED
Date:March 2018
Journal or Publication Title:Fuel Cells
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:18
DOI :10.1002/fuce.201700113
Page Range:pp. 239-250
Publisher:Wiley
ISSN:1615-6846
Status:Published
Keywords:Atomic Force Microscopy (AFM), Aquivion, Catalyst Layers, Electrolyzers, Fuel Cells, Humidity, Nafion, Swelling
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:19 Dec 2018 17:15
Last Modified:06 Sep 2019 15:15

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