Project acronym: LOLIPEM website address: www.lolipem.eu
title: Long-life PEM-FCH &CHP systems at temperatures ≥100°C
Funding Scheme: Fuel Cells and Hydrogen Joint Undertaking (FCH JU)
Funding board: EC (FP7) and FCH JU
Starting date: January 1st, 2010
Duration: 36 months
Date of latest version of Annex I against which the assessment will be made: December 2009
Deliverable number: D 4.3 Deliverable: workshop on ”Membrane materials: preparation and characterization” Contractual deliver date: M6, July 2009 Responsible: Partner P2 “Università di Roma ”Tor Vergata” Tel: +39 06 72594385 Fax: +39 06 72594328 E-mail: [email protected] Authors: “Maria Luisa DI VONA”
Dissemination Level
PU Public X
PP Restricted to other project participants (including the Commission Services)
CO Confidential, only for members of the consortium (including the Commission Services)
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1st International Workshop on
Long life membranes based on PFSA & SAPs:
Preparation and Characterization
Contents
INTRODUCTION ............................................................................................................5
LIST OF THE PARTICIPANTS...........................................................................................7
SCIENTIFIC PROGRAM ..................................................................................................9
ABSTRACT OF THE PRESENTED CONTRIBUTIONS ...................................................... 11
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INTRODUCTION The 1st International Workshop on Long life membranes based on PFSA & SAPs: Preparation and
Characterization, was organized by URoma2, Professor Maria Luisa DI VONA, in the framework of
LLooLLiiPPEEMM ((LLoonngg--lliiffee PPEEMM--FFCCHH && CCHHPP ssyysstteemmss aatt tteemmppeerraattuurreess ≥≥ 110000 °°CC)) EEUU PPrroojjeecctt. The workshop
was held in Grottaferrata (Rome), at Hotel Villa Grazioli on March 17th-18th 2011.
This workshop aimed to bring together scientists and students interested in the study and
development of new Polymer Electrolyte Membrane Fuel Cells.
The workshop was attended by well-known scientists from 8 countries: Italy, Germany, France,
Switzerland, Spain, Poland, UK, USA.
44 participants were present, with 17 oral presentations and 2 invited lectures. 9 presentations
was held by member of the Lolipem consortium and 10 by external scientists.
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The workshop featured all aspects of synthesis and both structural and functional characterization
of membranes, mainly perfluorosulfonic acid (PFSA) and sulfonated aromatic polymers (SAPs), with
emphasis on their application in PEMFCs operating above 100 °C.
The level of participants and contributions was very high and intense scientific discussions were
stimulated throughout the workshop.
Consensual was the importance of long-time tests of membranes to assess the degradation
phenomena. Industry representatives insisted also on the cost criterion, which makes complicated
materials developments unsuitable for application. To this day, Nafion and sulfonated aromatic
polymers appear as the most suitable membranes for “intermediate temperature” PEMFC.
Two relaxed dinners complemented the program.
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LIST OF THE PARTICIPANTS Giulio ALBERTI University of Rome Tor Vergata, Italy
Alicia ARCE MATGAS, Barcelona, Spain
Francesco ARENA Saarland University, Germany
Salvatore Antonino ARICÒ CNR - ITAE Italy
Morin ARNAUD LCPEM, CEA Grenoble, France
Giuseppe BARBIERI CNR-ITM, Italy
Brian BENICEWICZ University of South Carolina, USA
Davide BERETTA EDISON, Italy
Adele BRUNETTI CNR-ITM, Italy
Mario CASCIOLA University of Perugia, Italy
Vito DI NOTO University of Padova, Italy
Maria Luisa DI VONA University of Rome Tor Vergata, Italy
Thierry DJENIZIAN University of Provence, France
Anna DONNADIO ITM-CNR, Italy
Barbara GALLENZI University of Rome Tor Vergata, Italy
Bogna GROCHOLA Cracow University of Technology, Poland
Mariska HATTEMBERGER University of Birmingham, UK
Rolf HEMPELMANN Saarland University, Germany
Hou HONGYING University of Provence, France
Deborah JONES AIME, University of Montpellier II, France
Mustapha KHADHRAOUI University of Provence, France
Philippe KNAUTH University of Provence, France
Chrystelle LEBOUIN University of Provence, France
Luciana LUCHETTI University of Foggia, Italy
Francesco LUFRANO CNR - ITAE INSTITUTE, Italy
Brunella MARRANESI University of Rome Tor Vergata, Italy
Piercarlo MUSTARELLI University of Pavia, Italy
Riccardo NARDUCCI University of Perugia, Italy
Oriol J. OSSÒ MATGAS, Barcelona, Spain
Luca PASQUINI University of Rome Tor Vergata, Italy
Riccardo POLINI University of Rome Tor Vergata, Italy
Joaquim SALLERAS MATGAS, Barcelona, Spain
Jean- Yves SANCHEZ LEPMI-CNRS, Grenoble, France
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Guenther SCHERER Paul Scherrer Institute, Switzerland
Mauricio SCHIEDA Centre for Materials and Coastal Research, Germany
Michael SCHUSTER Fumatech, Germany
Emanuela SGRECCIA University of Rome Tor Vergata, Italy
Anna STACHOWICZ Cracow University of Technology, Poland
Rafael SZAMOCKI Saarland University, Germany
Elena TOCCI CNR-ITM, Italy
Sebastiano TOSTO ENEA, Italy
Florence VACANDIO University of Provence, France
Lourdes F. VEGA MATGAS, Barcelona, Spain
Thomas ZAWODZINSKI University of Tennessee, USA
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SCIENTIFIC PROGRAM
First International LoLiPEM Workshop. Long life membranes based on PFSA & SAPs: Preparation and characterization
Scientific Agenda
Thursday March 17, 2011
10.00 – 10.10 M. Luisa DI VONA, Welcome and presentation of LoLiPEM EU project
Chair: M. Luisa DI VONA, University of Rome Tor Vergata, Italy
10.10 – 11.10 Invited Lecture: Deborah JONES, AIME, University of Montpellier II, France
Cross-linking and other approaches to the mechanical stabilisation of PFSA membranes
11.10 – 11.30 Coffee Break
Chair: Guenther SCHERER, Paul Scherrer Institute, Switzerland
11.30 – 12.30 Giulio ALBERTI, University of Perugia, Italy
Understanding proton conductor ionomers in the temperature range 20-140°C
12.30 – 13.00 Tom ZAWODZINSKI, University of Tennessee, USA
Studies of proton conduction in new materials
13.00 – 14.30 Lunch
Chair: Jean-Yves SANCHEZ, LEPMI-CNRS, Grenoble, France
14.30 – 15.00 Antonino ARICÒ, CNR-ITAE, Messina, Italy
High temperature operation of solid polymer electrolyte fuel cells based on a short side chain perfluorosulphonic membrane in combination with designed electrocatalysts
15.00 – 15.30 Mario CASCIOLA, University of Perugia, Italy
Gravimetric determination of the water uptake of ionomeric membranes as a function of temperature at controlled relative humidity
15.30 – 16.00 Arnaud MORIN, LCPEM, CEA Grenoble, France
Consideration of mechanical aspects on the degradation of PFSA membranes
16.00 – 16.20 Coffee Break
Chair: Antonino ARICÒ, CNR-ITAE, Messina, Italy
16.20 – 16.50 Philippe KNAUTH, University of Provence, France
Ex-situ stability test of SAPs by thermogravimetric analysis
16.50 – 17.20 Brian BENICEWICZ, University of South Carolina, USA
Advances in PBI-PA membranes for high temperature PEM devices
17.20 – 17.50 Piercarlo MUSTARELLI, University of Pavia, Italy
New PBI-based membranes for HT-PEMFCs 19.30 Gala Social Dinner – Castel Gandolfo
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Friday March 18, 2011
Chair: Tom ZAWODZINSKI, University of Tennessee, USA
9.30 – 10.30 Invited Lecture: Guenther SCHERER, Paul Scherrer Institute, Switzerland
Degradation of solid polymer electrolytes in electrochemical cells. Some considerations
10.30 – 11.00 Francesco ARENA, Universität des Saarlandes, Germany Permeability measurements on polymer membranes for fuel cells
11.00 – 11.20 Coffee Break
Chair: Giulio ALBERTI, University of Perugia, Italy
11.20 – 11.50 Vito DI NOTO, University of Padova, Italy
Effect of the anions on the properties of proton-conducting membranes based on neutralized Nafion 117, triethylammonium methanesulfonate and triethylammonium perfluorobutanesulfonate
11.50 – 12.20 Mustapha KHADHRAOUI, University of Provence, France
Mechanical analysis of polymers
12.20 – 14.00 Lunch
Chair: Deborah Jones, AIME, University of Montpellier II, France
14.00 – 14.30 Michael SCHUSTER, Fumatech, Germany
Membrane development for fuel cells at FuMA-Tech
14.30 – 15.00 Jean-Yves SANCHEZ, LEPMI-CNRS, Grenoble, France
Membranes based on macroporous high performance polymers filled by a CLIP for high temperature PEMFC membranes
15.00 – 15.30 Alicia ARCE, Matgas, Barcelona, Spain
Study and implementation of advanced control technologies to maximize PEM fuel cell durability
15.30 – 15.50 Coffee Break
Chair: Philippe Knauth, University of Provence, France
15.50 – 16.20 Emanuela SGRECCIA, University of Rome Tor Vergata, Italy
Hybrid approach for improved SAP membranes
16.20 – 16.50 Francesco LUFRANO, CNR-ITAE, Messina, Italy
Development of Membranes Based on Sulfonated Polysulfone for Applications in Direct Methanol Fuel Cells
16.50 – 17.20 Giuseppe BARBIERI, ITM-CNR, Cosenza, Italy
Development of long life SAP membranes for PEMFCs based on SPEEK-WC
18.30 Medieval Night – Fumone
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Cross-linking and other approaches to the mechanical stabilisationof PFSA membranes
D. J. Jones and J. Rozière
ICGM-Aggregates, Interfaces and Energy Materials, University Montpellier 2
34095 Montpellier cedex 5, France
Properties of perfluorosulfonic acid (PFSA) membranes have been further improved in recent years following the better understanding of critical ageing processes. Despite these advances, the conductivity of PFSA at high temperature and low relative humidity is lower than that of the applications-driven target, and further improvement is still required. The limitation of the approach of increasing proton conductivity by lowering the polymer EW is that the polymer and membrane properties are also affected, with membranes showing increased water uptake and dimensional swelling. Cross-linking between polymer chains reduces swelling at high hydration levels, increases Tg, and improves membrane mechanical strength, and we have developed and screened a series of approaches for the covalent cross-linking of PFSAs in order to improve membrane mechanical properties and reduce membrane swelling in the presence of water.
On the one hand, novel side-chain component multifunctional monomers have been developed that are cross-linkable after membrane fabrication through the presence of reactive nitrile or bromide end groups. On the other, methodologies have been devised for cross-linking of low EW membranes in sulfonyl fluoride precursor form through reaction with a nitrogen-containing base to give sulfonamide end groups that are converted to sulfonimide cross-links on thermal curing. Here, the degree of cross-linking is regulated by the reaction conditions, and the probability of reaction is high. Further, there is no parasitic reaction as can occur in the case of residual –Br or –NC functions in unreacted side-chains. This presentation will describe the preparation and characterisation of a series of cross-linked PFSA membranes and will highlight the advantages and disadvantages of the various approaches.
[1] Y. M. Zhang, L. Li, J. K. Tang, B. Bauer, W. Zhang, H. R. Gao, M. Taillades-Jacquin, D. J. Jones, J. Rozière, N. Lebedeva and R. K. A. M. Mallant, Development of covalently cross-linked and
composite perfluorosulfonic acid membranes, ECS Trans., (2009) 25, 1469-147. Acknowledgements Funding through FP6 IPHE-GENIE and fruitful collaboration with Shanghai Jiao Tong University under contract 039016, are acknowledged with thanks.
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Studies of Proton Conduction in New Materials
Thomas A. Zawodzinski Jr.1,2*, Che-Nan Sun1,3, Manale Maalouf 1,3and Yujia Bai1
1) Department of Chemical and Biomolecular Engineering, University of Tennessee-Knoxville,
Knoxville, TN, USA 37996
2) Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
3 ) Case Western Reserve University, Cleveland, OH USA 44120
Many studies of polymer electrolytes have been reported, including detailed studies of
conductivity and other transport properties as functions of water content. Nonetheless, several
gaps remain in our physical data for membranes, leading to issues related to interpretation. In this
presentation, we will discuss our recent efforts to improve our understanding. We will focus on
new PFSAs developed at 3M.
One seemingly prosaic property that is necessary for several purposes is density of the
membrane as a function of water content. These include analysis of conductivity, thermodynamic
analysis of molar volume of polymers and water in the membrane and validation of theory.
Density of PFSA and other membranes is surprisingly difficult to measure due to the mixed
hydrophilic and hydrophobic character and the non-uniformity of the thickness of most
membranes. The former makes standard ‘density balance’ measurements based on Archimedean
displacement of fluids difficult since the membrane imbibes most fluids. We are exploring air
pycnometry as a solution to this and will discuss results and prospects for this method. We will
also discuss the application of this information to the analysis of conductivity in new 3M PFSAs.
For low EW 3M materials, we find surprisingly high rates of water motion, correlated to
high conductivity, at low water contents. Determining the polymer/water system density enables
a precise calculation of proton mobility. Preliminary estimates suggest that proton mobility is
indeed enhanced, beyond expected effects of EW (i.e. charge carrier concentration) on
conductivity. Finally, recent results obtained with ‘extended side-chain’ materials will be
described.
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High Temperature Operation of Solid Polymer Electrolyte Fuel Cells Based on a Short Side Chain Perfluorosulphonic Membrane in combination with Designed
Electrocatalysts
A. S. Aricò*, A. Stassi, I. Gatto, G. Monforte, E. Passalacqua, V. Antonucci
CNR-ITAE, Via Salita S. Lucia sopra Contesse 5 – 98126 Messina, Italy
L. Merlo, C. Oldani, E. Pagano
Solvay Solexis, viale Lombardia, 20 20021 - Bollate (MI) Italy
* Corresponding author: Tel.:+ 39090624237. fax: +39090624247. E-mail address: [email protected] (A.S. Aricò).
A new Aquivion® E79-03S short-side chain perfluorosulfonic membrane with a thickness of 30
μm (dry form) and an equivalent weight (EW) of 790 g/equiv developed by Solvay-Solexis for high-
temperature operation was tested in a polymer electrolyte membrane (PEM) single cell up to a
temperature of 130 °C and at pressures up to 3 bar abs. For comparison, a standard Nafion®
membrane (EW 1100 g/equiv) of similar thickness (50 μm) was investigated under similar
operating conditions (pressurised cell).
The membranes were tested in conjunction with designed CNR-ITAE carbon supported Pt and
Pt-Co electrocatalysts. The electrochemical tests showed better performance for the Aquivion™
membrane as compared to Nafion® with promising properties for high temperature PEM fuel cell
applications.
Beside the higher open circuit voltage and lower ohmic constraints, a higher electrocatalytic
activity was observed at high temperature for the electrocatalyst-Aquivion® ionomer interface
indicating a better catalyst utilization. High temperature stack testing carried out at CNR-ITAE in
the framework of the FP6 Autobrane project with Solvicore and JMFC MEAs confirmed the good
perspectives of the Aquivion® membrane for PEMFCs.
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Gravimetric determination of the water uptake of ionomeric membranes as a function of temperature at controlled relative humidity
M. Casciola1, M. L. Di Vona2, A. Donnadio3
1 Dipartimento di Chimica, Università degli Studi di Perugia,
via Elce di Sotto 8, 06123, Perugia, Italy 2 Dipartimento di Scienze e Tecnologie Chimiche, Università degli Studi di Roma Tor
Vergata, Via della Ricerca Scientifica 1,00133 Rome, Italy 3 National Research Council, Institute for Membrane Technology (ITM–CNR), Via Pietro
BUCCI, Cubo 17C, 87030 Rende CS, Italy
The determination of the water content of ionomeric membranes is of fundamental
importance for understanding the dependence of ionic conductivity on temperature and relative humidity (RH), but it is rather problematic when the membranes are equilibrated at high temperature and RH values. To solve this problem we built up an apparatus allowing the gravimetric determination of water uptake at temperature up to 140°C and RH in the range 30-90%.
The apparatus consists of two intercommunicating compartments held at different temperatures. The cold compartment contains water, while the hot compartment houses a glass container with the membrane under test. Relative humidity (RH) in the hot compartment is calculated from the ratio between the pressures of saturated water vapour (p) at the temperatures of the cold (Tc) and hot (Th) compartment: RH = 100·p(Tc)/p(Th). The apparatus is equipped with a device which allows closing the membrane container with a teflon plug without opening the cell. After a suitable equilibration time (usually half a day), the sample container is closed, extracted from the cell and weighed. The water content is determined on the basis of the difference between the weight of the hydrated and anhydrous ionomer, taking into account the amount of water trapped in the glass container at the temperature and the RH of the experiment. In this connection, it was checked that the amount of water trapped in the empty container corresponds to that calculated for certain temperature and RH values.
This technique was used to determine the water uptake of a membrane of sulfonated polyethersulfone (SPES) with IEC=1.31 meq/g as a function of temperature (70 – 120°C) at RH=75% and as a function of RH (50-90%) at 100°C. It was found that the conductivity hysteresis observed upon thermal cycling between 70 and 120°C is associated with an hysteresis in the membrane
hydration which increases from λ=7.4 to λ=8.4 during the heating run and keeps nearly unaltered when the membrane is cooled to 70°C. At 100°C, an RH increase from 50 to 90% determines an
increase in hydration from λ=5.9 to λ=8.1 and in conductivity from 4·10-3 to 4·10-2 S cm-1. Similar experiments are in progress on Nafion 117 membranes and on sulfonated aromatic polymers. Acknowledgements The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.
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Consideration of mechanical aspects on the degradation of PFSA membranes
A. Morin1, S. Escribano1, N. Otmani1, G. Gebel2
1 CEA-Grenoble, DRT/Liten/DEHT/LCPEM, 17 rue des Martyrs Cedex 9 F-38054 Grenoble (France)
2 CEA-Grenoble, DSM/INAC, UMR SPrAM 5819, 17 rue des Martyrs F-38054 Grenoble, Cedex 9 (France)
The mechanical properties of recast and extruded Nafion® membranes (Young modulus, yield
strength…) have been characterized as a function of temperature and relative humidity, as well as
immersed in water. Recast membranes have a more “plastic” behaviour than extruded one. These
properties have been used as input data for a model of the mechanical behaviour of this
membrane. Then, the mechanical stresses and deformation of the Nafion® 112 in an operating
PEMFC under cycling operation has been simulated. The results show a residual stress and
deformation after cycling.
In parallel, we demonstrated that the membrane’s structure becomes anisotropic under
compressive stress higher than 5 MPa at 100%RH and ambient
temperature.
More over tensile stress performed on extruded and recast Nafion membranes after ageing
under cycling load show that their mechanical properties have been modified. The modifications
are more important near the gas inlets compared to the gas outlets and are different for the
recast membrane than for the extruded one. Especially, the elongation at break for the recast
membrane is strongly reduced near the gas inlet which is much less pronounced for the extruded
one.
All these results indicate that the mechanical stresses during PEMFC operation induce physical
modifications of the membrane. They could be a major cause of the membrane degradation.
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Ex-situ stability test of Sulfonated Aromatic Polymers
by Thermogravimetric Analysis
P. Knauth and H. Hou
University of Provence, Laboratoire Chimie Provence (UMR 6264
Centre St Jerome, 13397 Marseille, France
In this talk, we will discuss the use of high resolution Thermogravimetric Analysis (TGA) for the ex
situ study of the stability of Sulfonated Aromatic Polymers (SAP). After a short introduction on
some basics of TGA, we will present :
- Study of decomposition products by coupling TGA with on-line Mass Spectrometry
- Analysis of thermal stability of SAP membranes
- Determination of Degree of Sulfonation and Degree of Cross-linking of SAP membranes and
comparison with acid-base titration results
Acknowledgements
The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher
than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.
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Advances in PBI-PA Membranes for High Temperature PEM Devices
Brian C. Benicewicz
Educational Foundation Distinguished Professor
Department of Chemistry and Biochemistry
USC NanoCenter
University of South Carolina
Columbia, SC 29208
Polybenzimidazole (PBI) polymers are excellent candidates for PEM fuel cell membranes
capable of operating at temperatures up to 200˚C. The ability to operate at high temperatures
may provide benefits such as faster electrode kinetics and greater tolerance to impurities in the
fuel stream. In addition, PBI membranes doped with phosphoric acid can operate efficiently
without the need for external humidification and the related engineering hardware to monitor
and control the hydration levels in the membrane. PBI membranes are currently being
investigated as candidates for portable, stationary, and transportation PEM fuel cell applications.
The development of the PBI membranes has also led to major advances in hydrogen
separation, purification, pumping, and compression technologies. The basic properties of these
membranes as high temperature (>100˚C) proton conductors, combined with the well-known
chemical stability, high tolerance to gas impurities, and potential for low cost, provide the
significant advancement in this enabling technology for hydrogen purification. In this
presentation, we will outline the development of the polymer membrane technology associated
with these devices and describe their applications in both the future hydrogen economy and
current industrial hydrogen gas user markets.
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New Pbi-Based Membranes For Ht-PEMFCs
P. Mustarelli
Dept. of Chemistry, University of Pavia, and INSTM, Via Taramelli 16, 27100 Pavia Italy
The current research on polymer electrolytes for fuel cells is focused on the optimization of
a membrane working at about 120°C and low humidity levels (<30%), which are the real operative
conditions in case of automotive applications (1). Among a wide variety of tested polymer
systems, PBI-based membranes, doped with phosphoric acid, are considered to be the best
alternative to Nafion, due to their high conductivity even with no or low humidification and other
promising electrochemical performances.
After a brief introduction on the problems of the membranes for HT-PEMFCs, I will report
on the experimental strategies followed in our laboratory in order to design better systems. First
of all new polymeric architectures, based on polybenzimidazole, have been synthesized with an
increased number of basic sites, differently interspaced along the polymer backbone.
Subsequently, composite membranes were prepared by dispersing in the previously prepared
matrices micro- and nanosized fillers, which differ for morphology, microstructure and chemical
nature. Finally, new monomers including oxygen and other chemical moieties have been
synthesized, and the consequent polymer have been prepared. Both in situ-electrochemical tests
and impedance spectroscopy were performed to evaluate the MEA performances.
1. P. Mustarelli, Fuel Cells, 10 (2010) 753.
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Degradation of Solid Polymer Electrolytes in Electrochemical Cells Some Considerations
Günther G. Scherer
Electrochemistry Laboratory
Paul Scherrer Institut 5232 Villigen Switzerland
A solid polymer electrolyte offers interesting features with respect to the engineering of the cell
design, however, also specific implications. This is particularly true for the concept realized in fuel
cell mode. The dual function of serving as electrolyte and gas separator asks for a multitude of
specific material properties, which have to be considered in the context of the duty cycle of the
total fuel cell system.
Next to performance and cost, longevity is an issue of paramount interest. Here again, the solid
polymer electrolyte, exposed to an extremely hash environment of simultaneously present H2, O2,
H2O, Pt-particles with nano dispersion, higher temperature and pressure, etc. is prone to be the
weak link of the whole component chain.
Next to integral degradation effects, specific local degradation of the polymer membrane show up
due to inhomogeneous reaction conditions, e.g., current density, temperature, gas concentration,
humidity, etc., within the electrochemical reactor fuel cell.
The presentation describes some of these specific local effects, points to advanced
characterization methods and gives an outlook on further challenges.
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Permeability and Diffusivity Measurements on Membranes for H2-PEMFC’s
Francesco Arena, Rafael Szamocki, Rolf Hempelmann
Physical Chemistry, Saarland University, 66123 Saarbrücken, Germany
After a brief review about the technique the results of hydrogen permeability and
diffusivity measurements, carried out with Nafion 117, 115 membranes, are presented. Up to now
all measurements were performed in a dry membrane state at different temperatures. A setup for
the future experimental determination of hydrogen- and oxygen permeability is presented
allowing measurements not only at different temperatures (from room temperature up to 120 °C),
but also at different relative humidities (0% up to 90%). This test bench includes a highly non-
corrosive measurement cell, as well a thermosetting unit, a gas humidifier, and a gas
chromatograph for quantitative gas analysis
.Acknowledgements
The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher
than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.
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Effect of the anions on the properties of proton-conducting membranes based on neutralized Nafion 117®, Triethylammonium methanesulfonate and
Triethylammonium perfluorobutanesulfonate
Vito Di Notoa,b, Matteo Pigaa, S. Lavinaa, G. Paceb, G. Giffina
aDipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, I-35131 Padova (Pd),
Italy. bIstituto di Scienze e Tecnologie Molecolari del CNR (CNR-ISTM) c/o Dipartimento di Scienze
Chimiche, Via Marzolo 1, I-35131 Padova (Pd), Italy.
In order to obtain proton exchange membranes (PEMs) that can operate at temperatures greater
than 120°C and in anhydrous conditions, innovative materials based on polymeric membranes doped with proton-conducting ionic liquids (PCILs) have been recently developed1-3. In this report the effect of the proton-conducting ionic liquid (PCIL) anion structure on the properties of a Nafion 117® membrane neutralized with triethylammonium (TEA+) (nN117) and doped with PCILs is presented. This work describes the synthesis and properties of proton-conducting membranes obtained by the treatment of nN117 with one of the following ionic liquids: triethylammonium methanesulfonate (TMS) and triethylammonium perfluorobutanesulfonate (TPFBu). The resulting PCIL-doped membranes are labelled NTMS and NTPFBu, respectively. The thermal and mechanical properties of the membranes are investigated by TG, DSC and DMA analysis. Results indicate that: (a) the membranes are thermally stable up to 140°C; (b) the uptake of ionic liquid is ca. 25 and 40 wt% for NTMS and NTPFBu, respectively; and (c) the mechanical properties of the membranes collapse at T > 140°C. Information about the structure and the interactions between different components of the membranes is examined with FT-IR ATR spectroscopy. Broadband electric spectroscopy is used to investigate molecular relaxation and polarization phenomena. Results for the pure PCILs indicate that: (a) three interfacial polarizations associated with different mechanisms of proton transfer exist above the melting point; and (b) conductivities
of σTMS = 1.4·10-2S/cm and σTPFBu = 9·10-3S/cm at 130°C. Results for the doped membranes reveal: (a) the mechanism of long range charge transfer, which is mediated by the dynamics of the fluorocarbon polymeric matrix and of the ionic liquids; (b) three interfacial polarizations, which are dependent on the nanostructuring phenomena of the ionic liquid contained within the polar
domains of NTMS and NTPFBu; (c) two dielectric relaxations α and β, which are associated with the dipolar relaxations involving the ionic liquids and the nN117 matrix below the melting point of
the PCILs; and (d) conductivities of σNTMS = 6.1·10-3 S/cm and σNTPFBu = 1.8·10-3S/cm at 130°C. The results allow a mechanism of proton conduction to be proposed for both the pure ionic liquids and the doped membranes. (1) Lee, S. Y.; Ogawa, A.; Kanno, M.; Nakamoto, H.; Yasuda, T.; Watanabe, M. J. Am. Chem. Soc.
2010, 132, 9764. (2) Di Noto, V.; Negro, E.; Sanchez, J. Y.; Iojoiu, C. J. Am. Chem. Soc. 2010, 132, 2183. (3) Martinez, M.; Molmeret, Y.; Cointeaux, L.; Iojoiu, C.; Lepretre, J. C.; El Kissi, N.; Judeinstein,
P.; Sanchez, J. Y. J. Power Sources 2010, 195, 5829.
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Mechanical analysis of Polymers
M. Khadhraoui, H. Hou, and P. Knauth
University of Provence, Laboratoire Chimie Provence (UMR 6264)
Centre St Jerome, 13397 Marseille, France
The properties of solid polymeric materials depend strongly on the microscopic
arrangement of molecules and chains configuration. These properties depend also on the initial
chemical composition, the different compounds and the modifications introduced by grafting,
branching or cross-linking.
The tensile test is usually used to determinate the different mechanical characteristics of
membrane such as: Young’s Modulus (E) , Yield Stress (σy) tensile strength (σTS), elongation at
rupture (εr), ductility, brittle behaviours. These characteristics are linked to the microstructure and
the architecture or the configuration of chains in the three dimensions.
In this talk, we will present:
- The definitions of different mechanical characteristics obtained from Stress-Stain curves.
- The behaviour of membrane polymers under tensile tests
- The influence of the condition test and the effects of temperature (T) and Relative
humidity (RH) on mechanical properties.
- The Relaxation and the complex and varied experimental results
The selected illustrations, in this talk, concern the polymers materials sPEEK, PPSU, Nafion, and
some are issued from bibliography.
Acknowledgements
The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher
than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.
GA N° 245339 Deliverable D4.3
25
Membranes based on macroporous High Performance Polymers filled by a
CLIP for High Temperature PEMFC membranes
D. Langevin1, Q.T. Nguyen1, S. Marais1, C. Chappey1, S. Karademir1, C. Iojoiu2, M. Martinez2, N. El Kissi3, R. Mercier4, J-Y.Sanchez2,*
1. PBS – UMR CNRS 6270 & FR 3038. Université de Rouen, 76821 Mont-Saint-Aignan, France. 2. LEPMI – UMR 5279, CNRS, Grenoble INP, UdS, UJF, BP 75, 34402 Saint-Martin-d’Hères cedex,
France. 3. Laboratoire de Rhéologie, UMR 5520, BP 53, 38041 Grenoble cedex
4. LMOPS – UMR 5041, BP 24, 69390 Vernaison, France.
This contribution deals with new proton conducting membranes based on a macroporous
polymeric separator filled by a proton conducting ionic liquid, CLIP. The macroporous separator,
made from an amorphous High Performance polymer having a high Tg, was prepared by vapour
induced phase inversion (VIPS) in order to obtain highly interconnected porous films. The CLIP
tested is obtained by reacting a sulfonic acid with a tertiary amine and presents high enough
thermal stability to be used at elevated temperature. Membrane samples were prepared by
immersing macroporous films in the previous CLIP. The macroporous separator was characterized
by SEM, gas permeation and TGA tests. The conductivities and the mechanical performances of
the filled separators were investigated. The proton conductivity of the previous membrane was
only slightly decreased with regard to the pure ionic liquid (20 mS/cm as compared to 31 mS/cm at
130°C) and exhibited, up to at least 150°C, storage moduli exceeding 200 MPa. This combination
of high mechanical strength and low conductivity loss make these new membranes very attracting.
GA N° 245339 Deliverable D4.3
26
Study and implementation of advanced control technologies to maximize
PEM fuel cell durability
Alicia Arce, J. Oriol Ossó, Carlos Bordons and Lourdes F. Vega
MatGas
Campus de la Universitat Autònoma de Barcelona 08193 Barcelona - Spain
Polymer Electrolyte Membrane (PEM) fuel cells are considered good candidates for
replacing conventional power sources in stationary and automotive applications due to the fact
that they present good properties such as fast start-up, high power density and low operating
temperature (60-120oC). However, the relatively short life of these fuel cells is a significant
drawback to their commercialization. Therefore, an appropriate fuel cell operation is essential in
order to optimize global efficiency and reduce degradation effects on the membrane. In this work
we report on the study and implementation of advanced control technologies for the optimization
of PEM fuel cells operation. Model predictive control formulations are proposed to regulate PEM
fuel cell systems. In particular, air supply and temperature are herein studied because since these
variables are strongly related to degradation effects and global efficiency. Moreover, the feasibility
of real-time implementation of these controllers is demonstrated by experimental tests. These
advanced control strategies are implemented in the test-bench developed at Matgas under the
LoLiPEM project for long-term durability tests of high-temperature PEM fuel cells manufactured
with membranes developed by LoLiPEM partners.
Acknowledgements
The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher
than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.
GA N° 245339 Deliverable D4.3
27
Hybrid approach for improved SAP membranes
E. Sgreccia,1,2 P. Knauth,2 M. L. Di Vona1
1Dipartimento di Scienze e Tecnologie Chimiche, Università degli Studi di Roma Tor Vergata,
Via della Ricerca Scientifica 1,00133 Rome, Italy 2University of Provence, Laboratoire Chimie Provence (UMR 6264), Centre St Jerome, 13397
Marseille, France
In the quest for improved PEM fuel cell membranes, composite materials offer a
supplementary degree of freedom for conception. Mechanically reinforced composite SPEEK
membranes were prepared by addition of a silylated PPSU minority phase with phenyl-silanol
groups. The secondary phase maintains the mechanical stability of the membrane, whereas the
main component is responsible for proton conduction. Water uptake coefficients are spectacularly
lower than those of pure SPEEK. A clear correlation exists between the water uptake coefficient
and the elastic modulus of the membranes. At 100 C, proton conductivity decreases above 85% RH
for pure SPEEK, but continues to increase for the polymer blend. The membrane preparation must
be further simplified in order to be industrially applicable. A second strategy relies on the
simultaneous presence of the polymer matrix and inorganic, organically surface-modified titania
particles. In principle, this method allows modulating the desired properties by changing surface
functionalization and concentration of oxide particles with the goal of synergistic effects between
the two components. With hydrophilic titania, the proton conductivity is high, but the membranes
are inhomogeneous due to titania agglomeration. Membranes with hydrophobic titania are
instead very homogeneous, but lack high conductivity.
GA N° 245339 Deliverable D4.3
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Development of Membranes Based on Sulfonated Polysulfone for Applications in Direct Methanol Fuel Cells
Francesco Lufrano*, Vincenzo Baglio, Orazio Di Blasi, Pietro Staiti,
Vincenzo Antonucci, Antonino S. Aricò
CNR – ITAE, Istituto di Tecnologie Avanzate per l’Energia “Nicola Giordano” Via Salita S. Lucia sopra Contesse n. 5 - 98126 S. Lucia - Messina, Italy
Nowadays, acidic polymer electrolytes based on perfluorosulfonic-acid membranes are widely used as electrolytes (e.g. Nafion-type membranes) in different applications, but high cost, low operating temperature, and high methanol crossover of Nafion membranes have limited their widespread commercial application1,2. These drawbacks have stimulated scientists worldwide to develop new materials as Polymer Electrolyte Membranes (PEMs) based on sulfonated aromatic polymers (SAPs) as an alternative to Nafion for application in DMFCs.
This paper reports on the research and development of PEMs based on composite membrane of sulfonated polysulfone and modified silica materials for application in a DMFC at different operating temperatures. The sulfonated polysulfone (SPSf) was synthesized using trimethyl silyl chlorosulfonate as the sulfonating agent in a homogeneous phase of chloroform3, whereas silica was modified by treatment with chlorosulfonic acid at room temperature4. The ion exchange capacities of sulfonated polymer were varied from 1.2 to 1.6 meq g-1 changing the mole ratio between the sulfonating agent and monomer unit of polymer. The composite membranes based on sulfonated polysulfone and modified silica were prepared by using a casting method from dimethyl acetamide solutions. Structural characterizations by scanning electron microscopy and infrared spectroscopy were carried out on the composite membranes. Moreover, they were characterized in terms of ion exchange capacity, methanol/water uptake, proton conductivity, thermal properties, and DMFC performance at various temperatures. The whole study involved (a) the choice of preparative conditions influencing the synthesis of sulfonated polysulfone, (b) the modification of silica and the optimization of silica content in the composite membrane, (c) the investigation of membranes as polymer electrolytes in DMFC single cell at different temperatures and d) life-time investigation.
The membrane of sulfonated polysulfone containing 10 wt.% of modified silica showed a promising performance in DMFC investigations at temperatures comprised between 30°C and 60°C. A maximum power density of 60 mW cm-2 was obtained at 60°C feeding 1M methanol solution at the anode and dry air at the cathode, both at atmospheric pressure. A preliminary short durability test for 100 h showed any performance decay during chrono-amperometry measurement (60 mA/cm2) at 30°C.
1. V. Neburchilov, J. Martin, H. Wang, J. Zhang, J. Power Sources, 169 (2007) 221-238. 2. M.A. Hickner, H. Ghassemi, Y.S. Kim, B.R. Einsla, J.E. McGrath, Chem. Rev. 104 (2004) 4587-
4612. 3. F. Lufrano, V. Baglio, P. Staiti, A. Stassi, A.S. Arico’, V. Antonucci, J. Power Sources 195 (2010)
7727–7733. 4. M.A. Zolfigol, Tetrahedron 57 (2001), 9509-9511.
GA N° 245339 Deliverable D4.3
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Development of long life SAP membranes for PEMFCs based on SPEEK-WC
Enrica Fontananova1, Adele Brunetti1, Hongying Hou2, Philippe Knauth2, Francesco Trotta3, Enrico Drioli1, Giuseppe Barbieri1*
1The Institute on Membrane Technology (ITM-CNR), National Research Council, c/o The University of Calabria, Cubo 17C, Via Pietro Bucci, 87036 Rende CS, Italy;
2 Université de Provence-CNRS: Laboratoire Chimie Provence (UMR 6264), Centre St Jérôme, 13397 Marseille, France
3 Dep. of Chemistry, University of Torino, Via Pietro Giuria 7, 10125 Torino, Italy
Currently the most commonly used proton exchange membranes (PEMs) for fuel cell (FC) applications are based on perfluorosulfonic acid (PFSA) polymers, like Nafion. These PEMs have high proton conductivity and an excellent chemical stability. However, PFSA membranes have also high costs and an excessive permeability to the reagent species (H2 and O2 for H2-PEMFC; methanol and O2 for direct methanol -PEMFC) which limits not only the efficiency of the process, but also the Membrane Electrode Assembly (MEA) durability. A further disadvantage of the PFSA membranes is their relevant loss of conductivity if operated for a long period of time above 80 °C, because of dehumidification problems and irreversible anisotropic swelling [1]. As possible alternative to the expensive PFSA membranes, a huge number of non-fluorinated sulfonated aromatic polymer (SAP) membranes have been investigated [2]. In addition to their lower costs, another key aspect of SAP membranes is their usually lower gas and vapour permeability compared to PFSA membranes [3]. However non-fluorinated membranes are also generally characterized by a lower long-term stability in PEMFCs operative conditions. Consequently the development of PEMs able to conjugate low cost, high proton conductivity, good barrier properties and long-term stability is an important research area. In this work, ionomer membranes made of a sulfonated derivative of an amorphous polyetheretherketone, known as SPEEK-WC, have been prepared by solvent evaporation methods.
SPEEK-WC-based membranes are characterized by a lower methanol, H2 and O2 permeability with respect to Nafion 117. This difference is due to their lower diffusion coefficients, caused by the higher stiffness of the aromatic polymer chains of SPEEK-WC in comparison to the perfluorinated Nafion backbone [4].
In order to improve the durability of SPEEK-WC membranes three different strategies have been investigated: a) thermal annealing; b) blending with Nafion 1100 ionomer solutions c) chemical cross-linking with 1,5-diamino-2-methylpentane (DAMP). Ex-situ tests indicate that a particularly promising methodology for SPEEK-WC membranes is the third ones. In particular, TGA analyses indicate the formation of sulphonamide bonds in the membranes cross-linked with DAMP. These membranes showed increased hydrolytic and oxidative stability at high temperature (>100°C). However, a concomitant reduction in proton conductivity with respect to the un-treated samples was also observed. For these reasons, a systematic investigation of the cross-linking conditions has been carried out in order to optimize the membrane performance.
[1] G. Alberti , R. Narducci and M. Sganappa, J. Power Sources, 178 (2008) 575 [2] M. A. Hickner, H. Ghassemi, Y. S. Kim, B.R. Einsla, J.E. McGrath, Chem. Rev. 104 (2004) 4587 [3] K.D. Kreuer. J. Membrane Sci. 185 (2001) 29-39 [4] E. Fontananova, F. Trotta, J. C. Jansen, E. Drioli, J. Membr. Sci. 348 (2010) 326
Acknowledgements The EU-FP7 (FCH-JU) project “LoLiPEM - Long-life PEM-FCH &CHP systems at temperatures higher than 100°C” (GA 245339) is gratefully acknowledged for co-funding this work.