Solid Oxide Fuel Cells SOFCs

In a qualification of the above quotation, this book points out that the causes of things in the fuel cell industry literature are written without a logical thermodynamic basis. The author introduces such a basis, namely reversible isothermal oxidation. 

In this chapter, the Harvard-style references, many of which are patents, are grouped by manufacturer, and also appear in the main list of references at the end of the book. 

The conductivity of the prototype zirconia-type electrolytes becomes acceptable (with values of about 0.15 S/cm), only at temperatures above 900°C. For this reason the working temperature of fuel cells having such an electrolyte is between 900 and 1000°C. Such fuel cells are called conventional solid oxide fuel cells in the following chapters. 

Electrochemical Power Sources Batteries, Fuel Cells, and Supercapacitors, First Edition. Vladimir S. Bagotsky, Alexander M. Skundin, and Yurij M. Voltkovich 2015 John Wiley Sons, Inc. Published 2015 by John Wiley Sons, Inc. 

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Reactions (3.9) to (3.11) proceed rapidly to equilibrium in most anodic solid oxide fuel cell (SOFC) environments and thus H2 (Eq. 3.8) rather than CH4 is oxidized electrochemically resulting in low polarization losses. Upon doubling the stoichiometric coefficients of equation (3.8), summing equations (3.8) to (3.11) and dividing the resulting coefficients by two one obtains ... 

This reaction is of great technological interest in the area of solid oxide fuel cells (SOFC) since it is catalyzed by the Ni surface of the Ni-stabilized Zr02 cermet used as the anode material in power-producing SOFC units.60,61 The ability of SOFC units to reform methane "internally", i.e. in the anode compartment, permits the direct use of methane or natural gas as the fuel, without a separate external reformer, and thus constitutes a significant advantage of SOFC in relation to low temperature fuel cells. 

Solid oxide fuel cell, SOFC anodes, 97 catalysis in, 98,410 cathodes, 96... 

This presentation reports some studies on the materials and catalysis for solid oxide fuel cell (SOFC) in the author s laboratory and tries to offer some thoughts on related problems. The basic materials of SOFC are cathode, electrolyte, and anode materials, which are composed to form the membrane-electrode assembly, which then forms the unit cell for test. The cathode material is most important in the sense that most polarization is within the cathode layer. The electrolyte membrane should be as thin as possible and also posses as high an oxygen-ion conductivity as possible. The anode material should be able to deal with the carbon deposition problem especially when methane is used as the fuel. 

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). 

High-temperature solid-oxide fuel cells (SOFCs). The working electrolyte is a solid electrolyte based on zirconium dioxide doped with oxides of yttrium and other metals the working temperatures are 800 to 1000°C. Experimental plants with a power of up to lOOkW have been built with such systems in the United States and Japan. 

Oxide ion conductors have found widespread apphcations in our modem society. The devices based on oxide ion conductors include oxygen sensors, solid oxide fuel cells (SOFCs), and oxygen pump. 

There are six different types of fuel cells (Table 1.6) (1) alkaline fuel cell (AFC), (2) direct methanol fuel cell (DMFC), (3) molten carbonate fuel cell (MCFC), (4) phosphoric acid fuel cell (PAFC), (5) proton exchange membrane fuel cell (PEMFC), and (6) the solid oxide fuel cell (SOFC). They all differ in applications, operating temperatures, cost, and efficiency. 

Solid oxide fuel cell (SOFC) Aromatics <0.5%74 n.i. n.i. Fuel <5000 ppm75 Identified as fuel 76 Poison <1 ppm75 Poison (reversible) <0.1 ppm75 Tests ongoing on new materials to prove higher tolerances77-79... 

A fuel cell is a form of battery. An ordinary battery consists of internal reactants that are converted into electrical energy, whereas in a fuel cell the chemical reactants are supplied from an external source. There are several designs of fuel cell, one of which is the solid oxide fuel cell (SOFC). These employ calcia- or yttria-stabilized zirco-nia. The cells operate at temperatures of about 900°C, this high temperature being needed to maintain a high enough oxygen transport for useful cell output. 

B.C.H. Steele, K. Zheg, R.A. Rudkin, N. Kiratzis, M. Chrisitie, in M. Dokiya, O. Yamonoto, H. Tagawa, S.C. Singhal (eds.), Proceedings of the Fourth International Symposium on Solid Oxide Fuel Cells (SOFC-IV), June 1995, The Electrochemical Society, New Jersey, 1995, pp. 1028-1038. 

Pratihar SK, Baus RN, Mazumder S, and Maiti HS. Electrical conductivity and microstructure of Ni-YSZ anode prepared by liquid dispersion method. In Singhal SC, Dokiya M, editors. Proceedings of the Sixth International Symposium on Solid Oxide Fuel cells (SOFC-VI), Pennington, NJ The Electrochemical Society, 1999 99(19) 513-521. 

Basu RN, Blafi G, Buchkremer HP, Stover D, Tietz F, Wessel E, et al. Fabrication of simplified anode supported planar SOFCs—a recent attempt. In Yokokawa H, Singhal SC, editors. Proceedings of the Seventh International Symposium on Solid Oxide Fuel Cells (SOFC-VII), Pennington, NJ The Electrochemical Society, 2001 2001(16) 995-1001. 

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