Proton conducting fuel cells

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... 

Direct-methanol fuel cell Proton- conducting polymer membrane H+ (proton) 80-100... 

Hiibner, G. and Roduner, E. 1999. EPR investigation of HO radical initiated degradation reactions of sulfonated aromatics as model compounds for fuel cell proton conducting membranes. Journal of Materials Chemistry 9 409- 18. 

Keywords Compact fuel cell Proton conductive oxide Radiation induced conductivity Radiation enhanced diffusion... 

Figure 29. Conductivity of some intermediate-temperature proton conductors, compared to the conductivity of Nafion and the oxide ion conductivity of YSZ (yttria-stabilized zirconia), the standard electrolyte materials for low- and high-temperature fuel cells, proton exchange membrane fuel cells (PEMFCs), and solid oxide fuel cells (SOFCs).

The proton conductivity of the sulfonated PES is above 0.08 S cm , which is in the range needed for high-performance fuel cell proton exchange membranes and... 

Research has been conducted and is currently being conducted into several types of fuel cells, such as alkaline fuel cells, proton exchange membrane (PEM) fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, and so forth. Some of them are already commercialized, whereas others are close to commercialization. They are expected to find applications in almost every energy utilizing plant and/or device, from power plants to cars and homes, from laptop computers to mobile phones. 

The concept of the reversed fuel cell, as shown schematically, consists of two parts. One is the already discussed direct oxidation fuel cell. The other consists of an electrochemical cell consisting of a membrane electrode assembly where the anode comprises Pt/C (or related) catalysts and the cathode, various metal catalysts on carbon. The membrane used is the new proton-conducting PEM-type membrane we developed, which minimizes crossover. 

Polymer Electrolyte Fuel Cell. The electrolyte in a PEFC is an ion-exchange (qv) membrane, a fluorinated sulfonic acid polymer, which is a proton conductor (see Membrane technology). The only Hquid present in this fuel cell is the product water thus corrosion problems are minimal. Water management in the membrane is critical for efficient performance. The fuel cell must operate under conditions where the by-product water does not evaporate faster than it is produced because the membrane must be hydrated to maintain acceptable proton conductivity. Because of the limitation on the operating temperature, usually less than 120°C, H2-rich gas having Htde or no (

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. 

Today, the term solid electrolyte or fast ionic conductor or, sometimes, superionic conductor is used to describe solid materials whose conductivity is wholly due to ionic displacement. Mixed conductors exhibit both ionic and electronic conductivity. Solid electrolytes range from hard, refractory materials, such as 8 mol% Y2C>3-stabilized Zr02(YSZ) or sodium fT-AbCb (NaAluOn), to soft proton-exchange polymeric membranes such as Du Pont s Nafion and include compounds that are stoichiometric (Agl), non-stoichiometric (sodium J3"-A12C>3) or doped (YSZ). The preparation, properties, and some applications of solid electrolytes have been discussed in a number of books2 5 and reviews.6,7 The main commercial application of solid electrolytes is in gas sensors.8,9 Another emerging application is in solid oxide fuel cells.4,5,1, n... 

For last few years, extensive studies have been carried out on proton conducting inorganic/organic hybrid membranes prepared by sol-gel process for PEMFC operating with either hydrogen or methanol as a fuel [23]. A major motivation for this intense interest on hybrid membranes is high cost, limitation in cell operation temperature, and methanol cross-... 

A fuel cell is a layered structure consisting of an anode, a cathode, and a solid electrolyte (Fig. 8.31). Hydrogen reacts on the anode, typically Pt or Pt/Ru nano-particles deposited on a conducting graphite support, where it is oxidized into protons and electrons ... 

S. R. Narayanan, A. Kindler, B. Jeffries-Nakamura, W. Chun, H. Frank, M. Smart, S. Surampudi, and G. Halpert, in Proc. of the First International Symposium on Proton Conducting Membrane Fuel Cells, Ed. by S. Gottesfield, G. Halpert, and A. R. Landgrebe, The Electrochemical Society, Pennington, NJ, PV 95-23, 1995, pp. 261-266. 

Electrolytes for Electrochromic Devices Liquids are generally used as electrolytes in electrochemical research, but they are not well suited for practical devices (such as electrochromic displays, fuel cells, etc.) because of problems with evaporation and leakage. For this reason, solid electrolytes with single-ion conductivity are commonly used (e.g., Nafion membranes with proton conductivity. In contrast to fuel cells in electrochromic devices, current densities are much lower, so for the latter application, a high conductivity value is not a necessary requirement for the electrolyte. 

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