Polymer electrolyte-membrane fuel

Electro-catalysts which have various metal contents have been applied to the polymer electrolyte membrane fuel cell(PEMFC). For the PEMFCs, Pt based noble metals have been widely used. In case the pure hydrogen is supplied as anode fuel, the platinum only electrocatalysts show the best activity in PEMFC. But the severe activity degradation can occur even by ppm level CO containing fuels, i.e. hydrocarbon reformates[l-3]. To enhance the resistivity to the CO poison of electro-catalysts, various kinds of alloy catalysts have been suggested. Among them, Pt-Ru alloy catalyst has been considered one of the best catalyst in the aspect of CO tolerance[l-3]. 

The principle of the fuel cell was first demonstrated by Grove in 1839 [W. R. Grove, Phil. Mag. 14 (1839) 137]. Today, different schemes exist for utilizing hydrogen in electrochemical cells. We explain the two most important, namely the Polymer Electrolyte Membrane Fuel Cell (PEMFC) and the Solid Oxide Fuel Cell (SOFC). 

Outside of the double-layer region, water itself may be oxidized or reduced, leaving stable hydride, hydroxyl, or oxide layers on the electrode surface. These species may adsorb strongly and block sites from participating in electrocatalysis, as for example, hydroxyl species present at the polymer electrolyte membrane fuel cell... 

PEM Proton-exchange-membrane fuel cell (Polymer-electrolyte-membrane fuel cell) Proton- conducting polymer membrane (e.g., Nafion ) H+ (proton) 50-80 mW (Laptop) 50 kW (Ballard) modular up to 200 kW 25-=45% Immediate Road vehicles, stationary electricity generation, heat and electricity co-generation, submarines, space travel... 

Fig. 14.7 Cross section of a polymer electrolyte membrane fuel cell.

D. Wilkinson, D. Thompsett, "Materials and Approaches for CO and CO2 Tolerance for Polymer Electrolyte Membrane Fuel Cells," Proceedings of the Second International Symposium on New Materials for Fuel Cell and Modern Battery Systems, pp. 266-285, (Montreal, Quebec, Canada, July 6-10, 1997). 

D. P. Wilkinson and D. Thompsett. In Materials and approaches for CO and CO2 tolerance for polymer electrolyte membrane fuel cells, ed. O. Savadogo and P. R. Roberge, 266. Montreal Ecole Polytechnique de Montreal, 1997. 

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. 

Towne, S., Viswanathan, V., Holbery, J., and Rieke, P. Fabrication of polymer electrolyte membrane fuel cell MEAs utilizing inkjet print technology. Journal of Power Sources 2007 171 575-584. 

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. 

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. 

Poltarzewski, E., Stoiti, R, Alderucci, V., Wieczorek, W., and Giordano, N. Nation distribution in gas diffusion electrodes for solid polymer electrolyte membrane fuel cell applications. Journal of the Electrochemical Society 1992 139 761-765. 

Okamoto, K. 2003. Sulfonated polyimides for polymer electrolyte membrane fuel cell. Journal of Photopolymer Science and Technolgy 16 247-254. 

Jeske, M., Soltmann, C., Ellenberg, C., Wilhelm, M., Koch, D. and Grathwohl, G. 2007. Proton conducting membranes for the high temperature-polymer electrolyte membrane-fuel cell (HT-PEMFC) based on functionalized polysiloxanes. 

Figure 4.1 shows a schematic of a typical polymer electrolyte membrane fuel cell (PEMFC). A typical membrane electrode assembly (MEA) consists of a proton exchange membrane that is in contact with a cathode catalyst layer (CL) on one side and an anode CL on the other side they are sandwiched together between two diffusion layers (DLs). These layers are usually treated (coated) with a hydrophobic agent such as polytetrafluoroethylene (PTFE) in order to improve the water removal within the DL and the fuel cell. It is also common to have a catalyst-backing layer or microporous layer (MPL) between the CL and DL. Usually, bipolar plates with flow field (FF) channels are located on each side of the MFA in order to transport reactants to the... 

T. Erey and M. Linardi. Effects of membrane electrode assembly preparation on the polymer electrolyte membrane fuel cell performance. Electrochimica Acta 50 (2004) 99-105. 

M. Schulze, N. Wagner, T. Kaz, and K. A. Friedrich. Gombmed electrochemical and surface analysis investigation of degradation processes in polymer electrolyte membrane fuel cells. Electrochimica Acta 52 (2007) 2328-2336. 

Cho, E. A., U. S. Jeon, H. Y. Ha, et al. 2004. Gharacteristics of composite bipolar plate for polymer electrolyte membrane fuel cells. Journal of Power Sources 125 178-182. 

Wang, H., and J. A. Turner. 2004. Investigation of a duplex stainless steel as polymer electrolyte membrane fuel cell bipolar plate material. Journal of Power Sources. 128 193-200. 

The polymer electrolyte fuel cell (PEFC) or proton exchange membrane fuel cell—also known as the polymer electrolyte membrane fuel cell (PEMFC)—is a lower temperature fuel cell (typically less than 100°C) with a special polymer electrolyte membrane. This lower temperature fuel cell is well suited for transportation, portable, and micro fuel cell applications because of the importance of fast start-up and dynamic operation. The PEMFC has applicability in most market and application areas. 

Fig. 7.5 Polymer electrolyte membrane fuel cell (PEMFC)...

Figure 7.5 shows the polymer electrolyte membrane fuel cell (PEMFC). There are two porous metal plates connected in a circuit with a membrane between them. In... 

Polymer Electrolyte Membrane Fuel Cell (PEMFC) expensive catalysts required operates best at 60—90 °C... 

The beginning of modeling of polymer-electrolyte fuel cells can actually be traced back to phosphoric-acid fuel cells. These systems are very similar in terms of their porous-electrode nature, with only the electrolyte being different, namely, a liquid. Giner and Hunter and Cutlip and co-workers proposed the first such models. These models account for diffusion and reaction in the gas-diffusion electrodes. These processes were also examined later with porous-electrode theory. While the phosphoric-acid fuel-cell models became more refined, polymer-electrolyte-membrane fuel cells began getting much more attention, especially experimentally. 

Unlike alkaline, phosphoric acid, and polymer electrolyte membrane fuel cells, MCFCs don t reguire an external reformerto convert more energy-dense fuels to hydrogen. Due to the high temperatures at which they operate, these fuels are converted to hydrogen within the fuel cell itself by a process called internal reforming, which also reduces cost. 

There are a few distinct structural concepts for high-performance Pt alloy ORR electrocatalysts that are currently attracting much attention because they hold the promise of significant activity improvements compared to pure Pt catalysts. As a result of this, these electrocatalysts potentially offer the prospect to impact the future of Polymer Electrolyte Membrane fuel cell catalyst technology. 

The anode layer of polymer electrolyte membrane fuel cells typically includes a catalyst and a binder, often a dispersion of poly(tetraflu-oroethylene) or other hydrophobic polymers, and may also include a filler, e.g., acetylene black carbon. Anode layers may also contain a mixture of a catalyst, ionomer and binder. The presence of a ionomer in the catalyst layer effectively increases the electrochemically active surface area of the catalyst, which requires a ionically conductive pathway to the cathode catalyst to generate electric current (16). 

Species, Temperature, and Current Distribution Mapping in Polymer Electrolyte Membrane Fuel Cells... 

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