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Polymer-based fuel cell

Since this reaction involves ions, electrons, and gas molecules in three separate phases, the edge of the o/y interface that makes contact with the gas phase /3 is often described as the three-phase (or triplephase) boundary (TPB). The concept of the TPB actually dates to the 1920s, when workers studying the oxidation of H2 on platinum introduced this concept to explain why Pt must be exposed simultaneously to both solution and gas to get significant reaction. This type of electrode, which Schmid called die diffusiongaselektrode or gas-diffusion electrode (GDE), is still called this today by workers studying solution- or polymer-based fuel cells. As... [Pg.554]

Ramani, V., Swier, S., Shaw, M. T, Weiss, R. A., Kunz, H. R., and Fenton, J. M. Membranes and MEAs based on sulfonated poly(ether ketone ketone) and heteropolyacids for polymer electrolyte fuel cells. Journal of the Electrochemical Society 2008 155 B532-B537. [Pg.100]

The DMFC, based on a polymer electrolyte fuel cell (PEFC), uses methanol directly for electric power generation and promises technical advantages for power trains. The fuel can be delivered to the fuel cell in a gaseous or liquid form. The actual power densities of a DMFC are clearly lower than those of a conventional hydrogen-fed polymer electrolyte fuel cell. In addition, methanol permeates through the electrolyte and oxidizes at the cathode. This results in a mixed potential at the cathode (Hohlein et al., 2000). [Pg.229]

During the operation of a polymer-electrolyte fuel cell, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. Only through fimdamental modeling, based on physical models developed from experimental observations, can the processes and operation of a fuel cell be truly understood. This review examines and discusses the various regions in a fuel cell and how they have been modeled. [Pg.440]

Figure 3.18 Schematic diagram of a polymer electrolyte fuel cell based on a proton-conductive... Figure 3.18 Schematic diagram of a polymer electrolyte fuel cell based on a proton-conductive...
Polymer electrolyte fuel cell (PEFC) is considered as one of the most promising power sources for futurist s hydrogen economy. As shown in Fig. 1, operation of a Nation-based PEFC is dictated by transport processes and electrochemical reactions at cat-alyst/polymer electrolyte interfaces and transport processes in the polymer electrolyte membrane (PEM), in the catalyst layers consisting of precious metal (Pt or Ru) catalysts on porous carbon support and polymer electrolyte clusters, in gas diffusion layers (GDLs), and in flow channels. Specifically, oxidants, fuel, and reaction products flow in channels of millimeter scale and diffuse in GDL with a structure of micrometer scale. Nation, a sulfonic acid tetrafluorethy-lene copolymer and the most commonly used polymer electrolyte, consists of nanoscale hydrophobic domains and proton conducting hydrophilic domains with a scale of 2-5 nm. The diffusivities of the reactants (02, H2, and methanol) and reaction products (water and C02) in Nation and proton conductivity of Nation strongly depend on the nanostructures and their responses to the presence of water. Polymer electrolyte clusters in the catalyst layers also play a critical... [Pg.307]

Lefevre M, Proietti E, Jaouen F, Dodelet J-P. Iron-based catalysts with improved oxygen reduction activity in polymer electrolyte fuel cells. Science. 2009 324 71-4. [Pg.184]

Faubert, G. et ah. Activation and characterization of Fe-based catalysts for the reduction of oxygen in polymer electrolyte fuel cells, Electrochim. Acta, 43, 1969, 1998. [Pg.299]

Asensio, J.A., Borros, S., and Gomez-Romero, R, Polymer electrolyte fuel cells based on phosphoric acid-impregnated poly(2,5-benzimidazole) membranes, J. Electrochem. Soc., 151, A304, 2004. [Pg.306]

Polymer electrolyte-based fuel cells are emerging as attractive energy conversion systems suitable for use in many industrial applications, starting from a few milliwatts for portables to several kilowatts for stationary and automotive applications. The ability of polymer electrolyte fuel cells to offer high chemical to electrical fuel efficiency and almost zero emissions in comparison to today s prevailing technology based on internal combustion engines (ICEs) makes them an indispensable option as environmental concerns rise [1-6]. [Pg.760]

A publication by the Paul Scherrer Institute reports progress in preparing membrane/electrode assemblies for polymer electrolyte fuel cells based on radiation-grafted FEP PSSA membranes [95]. Hot-pressing with Nation was used to improve the interfaces. These improved MEAs showed performance data comparable to those of MEAs based on Nafion 112 (Figure 27.58) and an service-life in H2/O2 fuel cells of more than 200 h at 60°C and 500 mA cm. ... [Pg.800]

In this chapter, we will focus our discussion on the single polymer electrolyte fuel cell and will describe only briefly fuel cell stacks and complete power systems based on such cells. We will show how R D efforts at the cell level enhanced the understanding of key factors which determine PEFC performance, cost, and reliability and, consequently, enabled significant recent advancements in this fuel cell technology. [Pg.198]

The water distribution within a polymer electrolyte fuel cell (PEFC) has been modeled at various levels of sophistication by several groups. Verbrugge and coworkers [83-85] have carried out extensive modeling of transport properties in immersed perfluorosulfonate ionomers based on dilute-solution theory. Fales et al. [109] reported an isothermal water map based on hydraulic permeability and electro-osmotic drag data. Though the model was relatively simple, some broad conclusions concerning membrane humidification conditions were reached. Fuller and Newman [104] applied concentrated-solution theory and employed limited earlier literature data on transport properties to produce a general description of water transport in fuel cell membranes. The last contribution emphasizes water distribution within the membrane. Boundary values were set rather arbitrarily. [Pg.272]

PEM fuel cells use a solid proton-conducting polymer as the electrolyte at 50-125 °C. The cathode catalysts are based on Pt alone, but because of the required tolerance to CO a combination of Pt and Ru is preferred for the anode [8]. For low-temperature (80 °C) polymer membrane fuel cells (PEMFC) colloidal Pt/Ru catalysts are currently under broad investigation. These have also been proposed for use in the direct methanol fuel cells (DMFC) or in PEMFC, which are fed with CO-contaminated hydrogen produced in on-board methanol reformers. The ultimate dispersion state of the metals is essential for CO-tolerant PEMFC, and truly alloyed Pt/Ru colloid particles of less than 2-nm size seem to fulfill these requirements [4a,b,d,8a,c,66j. Alternatively, bimetallic Pt/Ru PEM catalysts have been developed for the same purpose, where nonalloyed Pt nanoparticles <2nm and Ru particles <1 nm are dispersed on the carbon support [8c]. From the results it can be concluded that a Pt/Ru interface is essential for the CO tolerance of the catalyst regardless of whether the precious metals are alloyed. For the manufacture of DMFC catalysts, in... [Pg.389]

Cipiti, F., Recupero, V., Pino, L., Vita, A., and Lagana, M. Experimental analysis of a 2kWe LPG-based fuel processor for polymer electrolyte fuel cells. Journal of Power Sources, 2006, 157 (2), 914. [Pg.117]

Fig. (19). Solar fuel cells based on the concept of a Polymer Electrolyte Fuel Cell (PEFC). Reproduced with permission from ref [176, 177]. 2006 National Academy of Science (left) 2010 American Association for the Advancement of Science (right). Fig. (19). Solar fuel cells based on the concept of a Polymer Electrolyte Fuel Cell (PEFC). Reproduced with permission from ref [176, 177]. 2006 National Academy of Science (left) 2010 American Association for the Advancement of Science (right).
Carbon aerogels and xerogels have been used as supports for Pt and Pt-based electrocatalysts for proton-exchange membrane fuel cells (PEMFCs), also known as polymer-electrolyte fuel cells [56,58,83-90], These fuel cells are convenient and environmentally acceptable power sources for portable and stationary devices and electric vehicle applications [91], These PEMFC systems can use H2 or methanol as fuel. This last type of fuel cell is sometimes called a DMFC (direct methanol fuel cell). [Pg.387]

A polymer electrolyte fuel cell stack with 100 cells and graphite-based bipolar plates is shown in a partly expanded view in Fig. 8.9. [Pg.349]

K.-B. Min, S. Tanaka, and M. Esashi, Fabrication of novel MEMS-based polymer electrolyte fuel cell architectures with catalytic electrodes supported on porous SiOj, Journal of Micromechanics and Microengineering, 16 (2006) 505-511. [Pg.143]


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