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Self-supporting Microporous Layers (MPLs) for PEM fuel cells

Bauder, Alexander and Haußmann, Jan and Markötter, Henning and Alink, Robert and Manke, Ingo and Scholta, Joachim and Friedrich, Kaspar Andreas (2012) Self-supporting Microporous Layers (MPLs) for PEM fuel cells. 3rd CARISMA International Conference on Medium and High Temperature Proton Exchange Membrane Fuel Cells, Kopenhagen, Dänemark.

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Abstract

The main requirements of a gas diffusion layer (GDL) of polymer electrolyte membrane fuel cells (PEMFC) are the provision of a gas and water transport as well as a significant electrical and thermal conductivity. The development of membrane electrode assemblies (MEA) for a wide temperature range (-20°C until +130°C) still favours membranes that require a certain level of humidification for sufficient proton conductivity. For the improvement of PEMFC diffusion media for these conditions, the still mostly unknown influence of the micro porous layer (MPL) on fuel cell performance is a major obstacle. An important function of the cathode side MPL at high temperature operation of PEMFCs is the prevention of membrane drying. However, concurrently a flooding of porous structures in the GDL or catalyst layers at lower temperatures has to be avoided. To get an insight that could lead to an improved GDL design for a broad range of operating conditions, a self-supporting MPL was developed, because this allows the manufacturing and the following treatments of the MPL independent from the GDL substrate. This MPL consists of a thin nonwoven synthetics coated on one side with a mixture of carbon and PTFE produced with the dry spraying technology. For in-situ experiments and some ex-situ measurements these layers are pressed with the non coated side on a commercial GDL without MPL (Sigracet® GDL25BA from SGL). To get a correlation of fuel cell performance to the global intrinsic properties of the MPL, like through-plane permeability, electrical conductivity or hydrophobicity, U(i)-curves up to limiting current densities and electrochemical impedance spectra are measured in a 5 cm² fuel cell setup. To obtain information about the influence of MPL structure on water distribution, synchrotron X-ray radiography studies were performed additionally. In such studies the importance of liquid water pathways through the porous structure for the water management is proven. With artificial paths in a carbon fibre GDL produced by laser perforation an overall performance gain has been obtained. With selfsupporting MPLs it was feasible to investigate the liquid water transport of nonperforated GDL/MPLs compared to the perforation of both layers as well as to the exclusive perforation of MPL and the GDL, by means of in-situ synchrotron imaging.

Item URL in elib:https://elib.dlr.de/77573/
Document Type:Conference or Workshop Item (Speech)
Title:Self-supporting Microporous Layers (MPLs) for PEM fuel cells
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Bauder, Alexanderalexander.bauder (at) dlr.deUNSPECIFIED
Haußmann, JanZSW UlmUNSPECIFIED
Markötter, HenningHZ BerlinUNSPECIFIED
Alink, RobertISE FreiburgUNSPECIFIED
Manke, IngoHZ BerlinUNSPECIFIED
Scholta, JoachimZSW UlmUNSPECIFIED
Friedrich, Kaspar Andreasandreas.friedrich (at) dlr.deUNSPECIFIED
Date:September 2012
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:PEM, GDL, MPL, water management, synchrotron imaging
Event Title:3rd CARISMA International Conference on Medium and High Temperature Proton Exchange Membrane Fuel Cells
Event Location:Kopenhagen, Dänemark
Event Type:international Conference
HGF - Research field:Energy
HGF - Program:Efficient Energy Conversion and Use (old)
HGF - Program Themes:Fuel Cells (old)
DLR - Research area:Energy
DLR - Program:E EV - Energy process technology
DLR - Research theme (Project):E - Elektrochemische Prozesse (old)
Location: Stuttgart
Institutes and Institutions:Institute of Engineering Thermodynamics > Electrochemical Energy Technology
Deposited By: Bauder, Alexander
Deposited On:05 Nov 2012 15:31
Last Modified:05 Nov 2012 15:31

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