Polymer electrolyte membrane properties

Ren, X. Springer, T. E. and Gottesfeld, S. (1998). Direct Methanol Fuel Cell Transport Properties of the Polymer Electrolyte Membrane and Cell Performance. Vol. 98-27. Proc. 2nd International Symposium on Proton Conducting Membrane Euel Cells. Pennington, NJ Electrochemical Society. 

Cho, Y. H., Yoo, S. J., Cho, Y. H., Park, H. S., Park, I. S., Lee, J. K., and Sung, Y. E. Enhanced performance and improved interfacial properties of polymer electrolyte membrane fuel cells fabricated using sputter-deposited Pt thin layers. Electrochimica Acta 2008 53 6111-6116. 

Bauer, F., Denneler, S. and Wilert-Porada, M. 2005. Influence of temperature and humidity on the mechanical properties of Nafion 117 polymer electrolyte membrane. Journal of Polymer Science Part B Polymer Physics 43 786-795. 

Patri, M., Hande, V. R., Phadnis, S. and Deb, P. C. 2004. Radiation-grafted solid polymer electrolyte membrane thermal and mechanical properties of sulfonated fluormated ethylene propylene copolymer (FEP)-graft-acrylic acid membranes. Polymers for Advanced Technologies 15 622-627. 

Physical models of fuel cell operation contribute to the development of diagnoshc methods, the rational design of advanced materials, and the systematic ophmization of performance. The grand challenge is to understand relations of primary chemical structure of materials, composition of heterogeneous media, effective material properties, and performance. For polymer electrolyte membranes, the primary chemical structure refers to ionomer molecules, and the composition-dependent phenomena are mainly determined by the uptake and distribuhon of water. 

The best hope for olefin/paraffin facilitated membrane separations seems to be the solid polymer electrolyte membranes discussed earlier, the results of which are shown in Figures 11.21 and 11.22. If stable membranes with these properties can be produced on an industrial scale, significant applications could develop in treating gases from steam crackers that manufacture ethylene and from polyolefin plants. 

A. Morisato, Z. He, I. Pinnau and T.C. Merkel, Transport Properties of PA12-PTMO/ AgBF4 Solid Polymer Electrolyte Membranes for Olefin/Paraffin Separation, Desalination 145, 347 (2002). 

M. Watanabe, H. Uchida, and H. Igarashi. Effects of polymer electrolyte membrane s property on fuel cell performances. Macromol-ecular Symposia 156, 223-230 2000. 

The material of PtRu alloy exhibits good properties for CO tolerance in polymer electrolyte membrane fuel cells (PEMFC) [68] and has been studied extensively in recent years [69]. Particular interest has been focused on the application of the PtRu alloy materials as anodes in methanol fuel cells (MFC) for electric vehicles [70]. The most convenient way to alter the surface composition of a PtRu alloy is to employ the electrochemical co-deposition method in the preparation of the alloy. Richcharz and co-workers have studied the surface composition of a series of PtRu alloys using X-ray photoelectron spectroscopy (XPS) and low-energy ion spectroscopy (LFIS)... 

Polymer electrolyte membrane materials and their properties... 

Carmo M, Roepke T, Roth C, dos Santos AM, Poco JGR, Linardi M (2009) A novel electrocatalyst support with proton conductive properties for polymer electrolyte membrane fuel cell applications. J Power Sources 191 330-337... 

For polymer electrolyte membrane fuel cell (PEMFC) applications, platinum and platinum-based alloy materials have been the most extensively investigated as catalysts for the electrocatalytic reduction of oxygen. A number of factors can influence the performance of Pt-based cathodic electrocatalysts in fuel cell applications, including (i) the method of Pt/C electrocatalyst preparation, (ii) R particle size, (iii) activation process, (iv) wetting of electrode structure, (v) PTFE content in the electrode, and the (vi) surface properties of the carbon support, among others. ... 

Solid polymer electrolytes, typically perfluorosulfonic acid (PFSA) membranes, are at the core of Polymer electrolyte membrane fuel cells (PEMFCs). These membranes electrically and mechanically isolate the anode and cathode while, when appropriately humidified, allowing for effective ion migration. Nafion, manufactured by DuPont, is one of the most thoroughly used and studied membranes in the PFSA family. Another family of membranes that holds some promise for use in PEMFCs is the group of sulfonated polyaromatic membranes, typically sulfonated polyetherketones. While research is being performed on other types of membranes, as well as hybrid membranes that might have been better-suited properties, information on these is searce [1-10]. 

M. Eikerling, A. A. Kornyshev, and U. Slimming, Electrophysical Properties of Polymer Electrolyte Membranes A Random Network Model, Journal of Physical Chemistry B, 101, 10807 (1997). 

The required properties of solid polymer electrolyte membranes may be divided into interfacial and bulk properties [9]. As described above, the interfacial characteristics of these membrane materials are important for the optimum formation of the three-phase boundary. Hence, flow properties, gas solubility, wetting of carbon supported catalyst surfaces by the polymer, etc. are of paramount importance. The bulk properties concern proton conductivity, gas separation, and mechanical properties. This whole ensemble of properties has to be considered and balanced in the development of novel proton-exchange membranes for fuel cell application. 

Abstract Chemical structure, polymer microstructme, sequence distribution, and morphology of acid-bearing polymers are important factors in the design of polymer electrolyte membranes (PEMs) for fuel cells. The roles of ion aggregation and phase separation in vinylic- and aromatic-based polymers in proton conductivity and water transport are described. The formation, dimensions, and connectivity of ionic pathways are consistently found to play an important role in determining the physicochemical properties of PEMs. For polymers that possess low water content, phase separation and ionic channel formation significantly enhance the transport of water and protons. For membranes that contain a high... 

Corrosion of the plates not only detracts from their mechanical properties but also gives rise to undesirable corrosion products, namely, heavy-metal ions, which, when depositing on the catalysts, strongly depress their activity. The corrosion processes also give rise to superficial oxide films on the metal parts, and these cause contact resistance of the surfaces. For a lower contact resistance, metallic bipolar plates sometimes have a surface layer of a more stable metal. Thus, in the first polymer electrolyte membrane fuel cell, developed by General Electric for the Gemini spacecraft, the bipolar plates consisted of niobium and tantalum coated with a thin layer of gold. A bipolar plate could also be coated with a layer of carbide or nitride. 

Fundamental properties of the materials such as polymer electrolyte membranes, catalysts and gas diffusion layers making up the so called Membrane Electrode Assembly (MEA) as well as requirements to bipolar plates and sealing concepts necessary for stack integration are discussed. 

Kawakami T, Shigemoto I (2005) Molecular-dynamics studies on the structures of polymer electrolyte membranes and the diffusion mechanism of protons and small molecules. In Nakahara M, Matubayasi N, Ueno M, Yasuoka K, Watanabe K (eds) Water, steam, and aqueous solutions for electric power. Proceeding of the 14th international conferance properties of water and steam. Maruzen Co., Ltd., Japan, pp 415 20... 

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