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Polymer Electrolyte Fuel Cells (polymer + electrolyte_fuel_cell)

Distribution by Scientific Domains

Chemistry	80%
Polymers and Materials Science	20%

Selected Abstracts

Special Issue of Fuel Cells , from Fundamentals to Systems devoted to selected papers presented at the international conference on Progress in MEA Components for Medium and High Temperature Polymer Electrolyte Fuel Cells

FUEL CELLS, Issue 4 2009
D. Jones
No abstract is available for this article. [source]

Radiation Grafted Membranes for Polymer Electrolyte Fuel Cells,

FUEL CELLS, Issue 3 2005
L. Gubler
Abstract The cost of polymer electrolyte fuel cell (PEFC) components is crucial to the commercial viability of the technology. Proton exchange membranes fabricated via the method of radiation grafting offer a cost-competitive option, because starting materials are inexpensive commodity products and the preparation procedure is based on established industrial processes. Radiation grafted membranes have been used with commercial success in membrane separation technology. This review focuses on the application of radiation grafted membranes in fuel cells, in particular the identification of fuel cell relevant membrane properties, aspects of membrane electrode assembly (MEA) fabrication, electrochemical performance and durability obtained in cell or stack tests, and investigation of failure modes and post mortem analysis. The application in hydrogen and methanol fuelled cells is treated separately. Optimized styrene,/,crosslinker grafted and sulfonated membranes show performance comparable to perfluorinated membranes. Some properties, such as methanol permeability, can be tailored to be superior. Durability of several thousand hours at practical operating conditions has been demonstrated. Alternative styrene derived monomers with higher chemical stability offer the prospect of enhanced durability or higher operating temperature. [source]

Hybrid Polymer Electrolyte Fuel Cells: Alkaline Electrodes with Proton Conducting Membrane

ANGEWANDTE CHEMIE, Issue 7 2010
Murat Ünlü Dr.
Kluges Management: Eine neuartige Brennstoffzellenarchitektur vereint die Stabilität und hohe Ionenleitfähigkeit von Protonenaustauschmaterialien (PEM) mit dem überlegenen elektrochemischen Verhalten von Anionenaustauschmembran(AEM)-Elektroden. Das Wassermanagement ist gegenüber klassischen Polymerelektrolytmembran-Brennstoffzellen deutlich verbessert, wobei eine Selbstbefeuchtung der Zelle erreicht wird. [source]

Membranen für Polymerelektrolyt-Brennstoffzellen,

CHEMIE-INGENIEUR-TECHNIK (CIT), Issue 11 2003
A. Glüsen Dr. rer. nat.
Abstract Die Polymerelektrolyt-Membran ist das Herzstück von wasserstoffbetriebenen Polymerelektrolyt-Brennstoffzellen (PEFC) und methanolbetriebenen Direktmethanol-Brennstoffzellen (DMFC). Membranen aus sulfonierten Fluoropolymeren sind derzeit kommerziell erhältlich. Wichtige Forschungs- und Entwicklungsziele sind derzeit für die PEFC die Erhöhung der Betriebstemperatur, ohne die Membran zusätzlich befeuchten zu müssen, und für die DMFC die Verringerung des Methanoltransportes durch die Membran. Zusätzlich sollen durch die Verwendung fluorfreier Polymere die Kosten der Membran und die Umweltbelastung reduziert werden. Dabei spielen bereits in der industriellen Entwicklung befindliche Membranen ebenso eine Rolle wie neue Membrankonzepte aus der Grundlagenforschung. Membranes for Polymer Electrolyte Fuel Cells The polymer electrolyte membrane is the heart of hydrogen fuelled Polymer Electrolyte Fuel Cells (PEFC) and methanol fuelled Direct Methanol Fuel Cells (DMFC). Membranes of sulfonated fluoropolymers are already commercially available. Important goals for research and development are for PEFCs an increased operating temperature without the need for additional humidification and for DMFC the reduction of methanol transport through the membrane. The use of non-fluorinated polymers aims at a reduction in membrane cost and environmental hazards. Membranes already in industrial product development are considered as well as novel membrane concepts in fundamental research. [source]

Radiation Grafted Membranes for Polymer Electrolyte Fuel Cells,

Hydrogen Production via Autothermal Reforming of Diesel Fuel

FUEL CELLS, Issue 3 2004
J. Pasel
Abstract Hydrogen, for the operation of a polymer electrolyte fuel cell, can be produced by means of autothermal reforming of liquid hydrocarbons. Experiments, especially with ATR 4, which produces a molar hydrogen stream equivalent to an electrical power in the fuel cell of 3,kW, showed that the process should be preferably run in the temperature range between 700,° and 850,°. This ensures complete hydrocarbon conversion and avoids the formation of considerable amounts of methane and organic compounds in the product water. Experiments with commercial diesel showed promising results but insufficient long-term stability. Experiments concerning the ignition of the catalytic reaction inside the reformer proved that within 60,s after the addition of water and hydrocarbons the reformer reached 95% of its maximum molar hydrogen flow. Measurements, with respect to reformer start-up, showed that it takes approximately 7,min. to heat up the monolith to a temperature of 340,° using an external heating device. Modelling is performed, aimed at the modification of the mixing chamber of ATR Type 5, which will help to amend the homogeneous blending of diesel fuel with air and water in the mixing chamber. [source]

In situ observation of water distribution and behaviour in a polymer electrolyte fuel cell by synchrotron X-ray imaging

JOURNAL OF SYNCHROTRON RADIATION, Issue 4 2008
Taihei Mukaide
In situ visualization of the distribution and behaviour of water in a polymer electrolyte fuel cell during power generation has been demonstrated using a synchrotron X-ray imaging technique. Images were recorded using a CCD detector combined with a scintillator (Gd2O2S:Tb) and relay lens system, which were placed at 2.0,m or 2.5,m from the fuel cell. The images were measured continuously before and during power generation, and data on cell performance was recorded. The change of water distribution during power generation was obtained from X-ray images normalized with the initial state of the fuel cell. Compared with other techniques for visualizing the water in fuel cells, this technique enables the water distribution and behaviour in the fuel cell to be visualized during power generation with high spatial resolution. In particular, the effects of the specifications of the gas diffusion layer on the cathode side of the fuel cell on the distribution of water were efficiently identified. This is a very powerful technique for investigating the mechanism of water flow within the fuel cell and the relationship between water behaviour and cell performance. [source]

Studies on a New Material for Hydrogen Storage and Supply by Modified Fe and Fe2O3 Powder

CHINESE JOURNAL OF CHEMISTRY, Issue 7 2007
Hui Wang
Abstract Modified iron oxide, a new material for hydrogen storage and supply to polymer electrolyte fuel cell (PEFC), was prepared by impregnating Fe or Fe2O3 powder with an aqueous solution containing metal cation additives (Al, Cr, Ni, Co, Zr and Mo). Hydrogen storage properties of the samples were investigated. The results show that both Fe and Fe2O3 powder with additive Mo presented excellent catalytic activity and cyclic stability, and their hydrogen producing temperature could be surprisingly decreased. The temperature of forming hydrogen for the Fe2O3 -Mo at the rate of 250 µmol·min,1·Fe-g,1 could be dramatically decreased from 527 °C before addition of Mo to 283 °C after addition of Mo in the fourth cycle. The cause for it was probably related to preventing the sinter of the sample particles. In addition, hydrogen storage capacity of the Fe2O3 -Mo can reach w=4.5% (72 kg H2/m3), close to International Energy Agency (IEA) criterion. These show the value of practical application of the Fe2O3 -Mo as the promising hydrogen storage material. [source]

High-Performance Alkaline Polymer Electrolyte for Fuel Cell Applications

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2010
Jing Pan
Abstract Although the proton exchange membrane fuel cell (PEMFC) has made great progress in recent decades, its commercialization has been hindered by a number of factors, among which is the total dependence on Pt-based catalysts. Alkaline polymer electrolyte fuel cells (APEFCs) have been increasingly recognized as a solution to overcome the dependence on noble metal catalysts. In principle, APEFCs combine the advantages of and alkaline fuel cell (AFC) and a PEMFC: there is no need for noble metal catalysts and they are free of carbonate precipitates that would break the waterproofing in the AFC cathode. However, the performance of most alkaline polyelectrolytes can still not fulfill the requirement of fuel cell operations. In the present work, detailed information about the synthesis and physicochemical properties of the quaternary ammonia polysulfone (QAPS), a high-performance alkaline polymer electrolyte that has been successfully applied in the authors' previous work to demonstrate an APEFC completely free from noble metal catalysts (S. Lu, J. Pan, A. Huang, L. Zhuang, J. Lu, Proc. Natl. Acad. Sci. USA2008, 105, 20611), is reported. Monitored by NMR analysis, the synthetic process of QAPS is seen to be simple and efficient. The chemical and thermal stability, as well as the mechanical strength of the synthetic QAPS membrane, are outstanding in comparison to commercial anion-exchange membranes. The ionic conductivity of QAPS at room temperature is measured to be on the order of 10,2,S cm,1. Such good mechanical and conducting performances can be attributed to the superior microstructure of the polyelectrolyte, which features interconnected ionic channels in tens of nanometers diameter, as revealed by HRTEM observations. The electrochemical behavior at the Pt/QAPS interface reveals the strong alkaline nature of this polyelectrolyte, and the preliminary fuel cell test verifies the feasibility of QAPS for fuel cell applications. [source]

Evolution of Permanent Deformations (or Memory) in Nafion 117 Membranes with Changes in Temperature, Relative Humidity and Time, and Its Importance in the Development of Medium Temperature PEMFCs,

FUEL CELLS, Issue 4 2009
G. Alberti
Abstract An important problem for medium temperature polymer electrolyte fuel cells (MT PEMFCs) operating in the temperature range 90,140,°C is the short time-life of proton conducting membranes. To shed some light on the empirical annealing treatments used for increasing the membrane durability, a systematic research on the effects of thermal treatments of Nafion 117 membranes was undertaken with the hope that the information obtained could be useful for a better understanding of the real limits for MT PEMFCs. Kinetic experiments showed that, for each couple of T,RH values, the water taken up from the membrane reaches a constant value only after long times of equilibration (,200,h). Taking into account that the enlargements provoked by the water-uptake remain as permanent deformations when the samples are cooled, it was found that the evolution of the deformations provoked by changes in temperature and RH can be conveniently estimated at 20,°C by determining the water taken up after equilibration in liquid water. By relating the counter-elastic index of the matrix (nc(m)) to the extent of these deformations, a set of equations were obtained which allowed us to predict their evolution with changes of temperature and relative humidity. A good agreement with experimental values was found. The importance of this discovery for the development of MT PEMFCs is discussed. [source]

Novel Polymer Electrolyte Membranes for Automotive Applications , Requirements and Benefits,

FUEL CELLS, Issue 4 2004
C. Wieser
Abstract During the past few years, the feasibility of using polymer electrolyte fuel cells in automotive power trains at an impressive performance level has been proven repeatedly. However, current fuel cell stacks are still largely based on decade-old polymer electrolyte membrane technology thus limiting performance, durability, reliability, and cost of the fuel cell systems. The major challenge for membrane R&D constitutes the demand for polymer electrolytes that allow for system operation at higher temperatures and lower water management requirements without increased conduction losses. None the less, demanding automotive requirements will not compromise on other properties such as mechanical and chemical stability and gas permeability. [source]

Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity range

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010
Guillaume Frutsaert
Abstract New alternating copolymers comprising a chlorotrifluorinated backbone and imidazole-terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton-conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three-step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI-alt-CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi-alt-CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi-alt-CTFE) with sPEEK lies in the range of 4,10 mS cm,1 at 40,70 °C and, for blend membranes rich in poly(Imi-alt-CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223,231, 2010 [source]

Polymer electrolyte membranes for high-temperature fuel cells based on aromatic polyethers bearing pyridine units

POLYMER INTERNATIONAL, Issue 11 2009
Joannis K Kallitsis
Abstract This review is focused on the design and synthesis of new high-temperature polymer electrolytes based on aromatic polyethers bearing polar pyridine moieties in the main chain. Such materials are designed to be used in polymer electrolyte fuel cells operating at temperatures higher than 100 °C. New monomers and polymers have been synthesized and characterized within this field in respect of their suitability for this specific application. Copolymers with optimized structures in order to combine excellent film-forming properties with high mechanical, thermal and oxidative stability and controlled acid uptake have been synthesized which, after doping with phosphoric acid, result in ionically conducting membranes. Such materials have been studied in respect of their conductivity under various conditions and used for the construction of membrane-electrode assemblies (MEAs) which are used for fuel cells operating at temperatures up to 180 °C. New and improved, in terms of oxidative stability and mechanical properties in the doped state, polymeric membranes have been synthesized and used effectively for MEA construction and single-cell testing. Copyright © 2009 Society of Chemical Industry [source]

Efficient fuel cell catalysts emerging from organometallic chemistry

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010
Helmut Bönnemann
Abstract During the last few decades organometallic methodologies have generated a number of highly effective electrocatalyst systems based on mono- and bimetallic nanosparticles having controlled size, composition and structure. In this microreview we summarize our results in fuel cell catalyst preparation applying triorganohydroborate chemistry, ,reductive particle stabilization' using organoaluminum compounds, and the controlled decomposition of organometallic complexes. The advantages of organometallic catalyst preparation pathways are exemplified with RuPt nanoparticles@C as promising anode catalysts to be used in direct methanol oxidation fuel cells (DMFC) or in polymer electrolyte fuel cells (PEMFC) running with CO-contaminated H2 as the feed. Recent findings with highly efficient PtCo3@C fuel cell catalysts applied for the oxygen reduction reaction (ORR) and with the effect of Se-doping on Ru@C ORR catalysts clearly demonstrate the benefits of organometallic catalyst synthesis. Copyright © 2010 John Wiley & Sons, Ltd. [source]