Polymer electrolyte fuel cell composite electrodes

Song, J. M., Cha, S. Y., and Lee, W. M. Optimal composition of polymer electrolyte fuel cell electrodes determined by the AG impedance method. Journal of Power Sources 2001 94 78-84. 

Figure 6.4. The polarization curves of fuel cells with electrodes that contain various PTFE content in the gas diffusion layer ( ) 10 ( ) 20 (A) 30 (+) 40 wt% [5]. (Reprinted from Journal of Power Sources, 94(1), Song JM, Cha SY, Lee WM. Optimal composition of polymer electrolyte fuel cell electrodes determined by the AC impedance method, 78-84, 2001, with permission from Elsevier and the authors.)...

Fig. 23. Schematic illustrations for solid polymer electrolyte fuel cell and composite electrode with Pt catalyst, carbon conducting material, and binding polymer material.

Polymer-electrolyte fuel cells (PEFC and DMFC) possess a exceptionally diverse range of applications, since they exhibit high thermodynamic efficiency, low emission levels, relative ease of implementation into existing infrastructures and variability in system size and layout. Their key components are a proton-conducting polymer-electrolyte membrane (PEM) and two composite electrodes backed up by electronically conducting porous transport layers and flow fields, as shown schematically in Fig. 1(a). 

Although in situ infrared spectroscopy has been applied widely in terms of the systems studied, the reflective electrodes employed have been predominantly polished metal or graphite, and so an important advance has been the study of electrochemical processes at more representative electrodes such as Pt/Ru on carbon [107,122,157], a carbon black/polyethylene composite employed in cathodic protection systems [158] and sol-gel Ti02 electrodes [159]. Recently, Fan and coworkers [160] took this concept one step further, and reported preliminary in situ FTIR data on the electro-oxidation of humidified methanol vapor at a Pt/Ru particulate electrode deposited directly onto the Nafion membrane of a solid polymer electrolyte fuel cell that was mounted within the sample holder of a diffuse reflectance attachment. As well as features attributable to methanol, a number of bands between 2200 and 1700 cm were observed in the spectra, taken under shortoperating conditions, the importance of which has already been clearly demonstrated [107]. 

Song, J.M., Cha, S.Y. and Lee, W.M. (2001) Optimal Composition of Polymer Electrolyte Fuel Cell Electrodes Determined by the AC impedance Method, J. Power Sources, 94, 78-84. 

Kamarajugadda, S., and Mazumder, S. Numerical investigation of the effect of cathode catalyst layer structure and composition on polymer electrolyte membrane fuel cell performance. Journal of Power Sources 2008 183 629-642. Krishnan, L., Morris, E. A., and Eisman, G. A. Pt black polymer electrolyte-based membrane-based electrode revisited. Journal of the Electrochemical Society 2008 155 B869-B876. 

Calculating the structural properties of the component from its chemical composition (e.g., for the case of polymer electrolyte membrane fuel cell (PEMFC) electrodes, by using coarse-grain molecular dynamics (CGMD)) (Fig. 10)... 

Lawrence, R. J., and Wood, L. D. Method of making solid polymer electrolyte catalytic electrodes and electrode made thereby. U.S. Patent 4,272,353,1981. Fedkiw, P. S., and Her, W. H. An impregnation-reduction method to prepare electrodes on Naifon SPE. Journal of the Electrochemical Society 1989 136 899-900. Aldebert, P, Novel-Cattin, R, Pineri, M., Millet, P, Doumain, G., and Durand, R. Preparation and characterization of SPE composites for electrolyzers and fuel cells. Solid State Ionics 1989 35 3-9. 

Quintus, M, Composite Electrodes and Membranes for Polymer Electrolyte Membrane Fuel Cells, PhD Thesis, University of Stuttgart, 2002, urn nbn de bsz 93-opus-12074 A, Dillon, K,M, Jones, T,A, Bekkedahl, C,H, Kiang, D,S, Bethune, M,J, Heben, Nature 386, 1997,377... 

The reactions in fuel cells have much lower rates than those in other batteries, so they require an electrocatalyst to decrease the activation energy (Section 16.8). The PEM cell electrodes are composites consisting of nanoparticles of a Pt-based catalyst deposited on graphite. These are embedded in a polymer electrolyte membrane having a perfluoroethylene backbone (-- F2C—CF2]-,r) with attached sulfonic acid groups (RS03 ) that play a key role in ferrying protons from anode to cathode. 

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