Solid oxide fuel cell electrolytes ceria-based

Kirk, T.J. and Winnick, J., A hydrogen sulfide solid-oxide fuel cell using ceria-based electrolytes, J. Electrochem. Soc., 140, 3494-3496 (1993). 

Mogensen, M., Sammes, N. M., and Tompsett, G. A. (2000). Physical, chemical and electrochemical properties of pure and doped ceria. Solid State Ionics 129 63-94. Godickemeier, M., and Gauckler, L. J. (1998). Engineering of solid oxide fuel cells with ceria-based electrolytes. J Electrochem. Soc. 145 414—421. 

Goedickemeier M, Gauckler LJ (1998) Engineering of solid oxide fuel cells with ceria-based electrolytes. J Electrochem Soc 145 414-421... 

Ceria affords a number of important applications, such as catalysts in redox reactions (Kaspar et al., 1999, 2000 Trovarelli, 2002), electrode and electrolyte materials in fuel cells, optical films, polishing materials, and gas sensors. In order to improve the performance and/or stability of ceria materials, the doped materials, solid solutions and composites based on ceria are fabricated. For example, the ceria-zirconia solid solution is used in the three way catalyst, rare earth (such as Sm, Gd, or Y) doped ceria is used in solid state fuel cells, and ceria-noble metal or ceria-metal oxide composite catalysts are used for water-gas-shift (WGS) reaction and selective CO oxidation. 

Oxides exhibiting only high ion conductivity are mainly fluorite-related structures based on zirconia or ceria. Zirconia-based electrolytes are currently used in solid oxide fuel cells (SOFCs). The MIEC oxides are more attractive for separative membrane applications, and these oxides mainly belong to the following types fluorite-related oxides doped to improve their electron conduction, - ... 

The principles behind this membrane technology originate from solid-state electrochemistry. Conventional electrochemical halfceU reactions can be written for chemical processes occurring on each respective membrane surface. Since the general chemistry under discussion here is thermodynamically downhill, one might view these devices as short-circuited solid oxide fuel cells (SOFCs), although the ceramics used for oxygen transport are often quite different. SOFCs most frequently use fluorite-based solid electrolytes - often yttria stabUized zirco-nia (YSZ) and sometimes ceria. In comparison, dense ceramics for membrane applications most often possess a perovskite-related lattice. The key fundamental... 

Zhu B, Li S and Mellander B (2010), Theoretical approach on ceria-based two-phase electrolytes for low temperature (300-600 C) solid oxide fuel cells , Electrochem Commim, 10,302-305. 

Inoue, T., Setoguchi, T., Eguchi, K., and Arai, H. (1989). Study of a solid oxide fuel cell with a ceria-based solid electrolyte. Solid State Ionics 35 285-291. 

Pinol, S. (2006) Stable single-chamber solid oxide fuel cells based on doped ceria electrolytes and Lao.5Sro.5Co03 as a new cathode. J. Fuel Cell Sci. Technol., 3, 434-437. 

Wang F, Chen S, Cheng S (2004b) Gd and Sm + co-doped ceria based electrolytes for intermediate temperature solid oxide fuel cells. Electrochem Commun 6 743-746... 

Other Oxide Electrolyte Systems Ceria-Based Electrolytes Ceria-based solid electrolytes have received an increasing attention for so-called IT-SOFC (solid oxide fuel cells for intermediate temperature) because of their high conductivity. But its electrolytic domain is relatively small so that the working temperature must not be higher than 700 °C without a remarkable loss in efficiency due to the electronic conductivity. By doping with aliovalent stable oxides, a remarkable increase of conductivity... 

Watanabe M, Uchida H, Yoshida M (1997) Effect of ionic conductivity of zirconia electrolytes on the polarization behavior of ceria-based anodes in solid oxide fuel cells. J Electrochem Soc 144(5) 1739-11743... 

On the other hand, there is a great demand for alternative fuel cells operating at moderate temperatures. In this context, intermediate temperature (400-800 °C) fuel cells are very attractive since they combine the advantages of both high- and low-temperature fuel cells such as fast electrode kinetics, fuel flexibility, and fewer degradation problems [7]. Furthermore, the tendency of lower temperatures makes conventional ceramic fuel cells (mainly solid oxide fuel cells SOFCs) a leading candidate for applications such as stationary power plants but also the possibility to replace internal combustion engines in vehicles [8]. Ceramic fuel cells based on ceria-carbonate salt composite electrolytes have been intensively studied for the past decade... 

The solid oxide fuel cell (SOFC) has been under development over several decades since it was invented by Baur and Preis in 1937. In order to commercialize this high temperature (600-1000 °G) fuel cell it was necessary to reduce the costs of fabricadon and operadon. Ceria-based materials are of potendal interest as both pure and doped ceria may help to decrease the internal electrical resistance of an SOFC by reducing the ohmic resistance of the electrolyte as well as the polarizadon resistance of both the fuel and the air electrode. Furthermore, the possibility of less fuel pre-treatment and having a lower water (steam) content in the natural gas fuel intended for the SOFC, due to the lower suscepdbility towards coke formation of ceria-containing fuel electrodes, may simplify the fuel cell system. Finally, ceria-based anodes seem less sensidve to poisoning by fuel impurities such as sulfur. The same type of cell has been developed for electrolysis and then called a solid oxide electrolysis cell (SOEC). As it is basically the same cell in both applicadons, it is often referred to as a solid oxide cell (SOC). It is anticipated that... 

A key factor in the possible applications of oxide ion conductors is that, for use as an electrolyte, their electronic transport number should be as low as possible. While the stabilised zirconias have an oxide ion transport number of unity in a wide range of atmospheres and oxygen partial pressures, the BijOj-based materials are easily reduced at low oxygen partial pressures. This leads to the generation of electrons, from the reaction 20 Oj + 4e, and hence to a significant electronic transport number. Thus, although BijOj-based materials are the best oxide ion conductors, they cannot be used as the solid electrolyte in, for example, fuel cell or sensor applications. Similar, but less marked, effects occur with ceria-based materials, due to the tendency of Ce ions to become reduced to Ce +. 

Therefore, it is not suitable to use ceria based solid electrolytes in the cell type shown in Figure 9-23. However, in the case for the other types shown Figures 9-29(a) and (b) [37], both the cathode and the anode are in the same atmosphere where air and fuel gas exist at the same time. Therefore, the volume change of the cell becomes negligible and it is greatly expected to apply the Sm-doped ceria which shows higher oxide ion conductivity than that of YSZ at intermediate temperature. 

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