Gd-doped ceria electrolyte

Ralph JM, Kilner JA, and Steele BCH. Improving Gd-doped ceria electrolytes for low temperature solid oxide fuel cells. Mater. Res. Soc. Symp. Proc. 1999 575 309-314. 

Refs. [i] http /lwww.seca.doe.gov [ii] http //www.spice.or.jp/ fisher/ sofc.html descript [iii] http //www.pg.siemens.com/en/fuelcells/sofc/ tubular/index.cfm [iv] Weissbart J, Ruka R (1962) J Electrochem Soc 109 723 [v] Park S, Vohs JM, Gorte RJ (2000) Nature 404 265 [vi] Liou J, Liou P, Sheu T (1999) Physical properties and crystal chemistry of bismuth oxide solid solution. In Processing and characterization of electrochemical materials and devices. Proc Symp Ceram Trans 109, Indianapolis, pp 3-10 [vii] Singhal SC (2000) MRS Bull 25 16 [viii] Matsuzaki Y, Yasuda I (2001) J Electrochem Soc 148 A126 [ix] Ralph JM, Kilner JA, Steele BCH (1999) Improving Gd-doped ceria electrolytes for low temperature solid oxide fuel cells. In New Materials for batteries and fuel cells. Proc Symp San Francisco, pp 309-314... 

Morales M, Pinol S, Segarra M (2009) Intermediate temperature single-chamber methane fed SOFC based on Gd doped ceria electrolyte and La(0.5)Sr (0.5)CoO(3-delta) as cathode. J Power Sources 194 961-966. doi 10.1016/j.jpowsour.2009.05.027... 

As with zirconia, ohmic losses can be significantly reduced by decreasing the thickness of the electrolyte. Burninskas and co-workers used Raman spectroscopy to characterise GDC electrolytes formed from solid state annealing of sputtered Gd203/Ce02 multilayers [71], Solid solutions of Gd doped ceria were observed to form when multilayer structures were annealed at a temperature of 900 °C. Films had to be annealed for more than one hour and prepared with a bilayer period of less than 70 mn in order to produce a well-ordered and uniformly doped phase. 

Gd-doped ceria mixed with Zr and Y, and various Ti02-based systems. In such anodes, there is mixed conductivity for both electrons and oxygen ions. A further advantage of using mixed conductors as anodes is that they can provide a means of extending the three-phase boundary between reactant-anode electrolyte, as shown in Figure 7.24. 

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. 

The effect of the YSZ coating on the ceria-based solid electrolyte was shown in Table 1. When the YSZ I SDC membrane was used as the solid electrolyte, selectivities to acrylaldehyde (Scho) carbon monoxide (Sco) and carbon dioxide (Scoa) based on converted propene was 13.4%, 25.6% and 61%, respectively. Here, it should be emphasized that the selectivity to acrylaldehyde increased with YSZ coating compared with that (Scho =8.5 %) obtedned by using SDC alone as a solid electrolyte. In addition, it was found that carbon monoxide formation was observed in the present study, although its formation was not detected in the case of SDC alone. The same phenomena were observed, when the Gd doped... 

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... 

Ceria doped with heterovalent cations, such as alkaline earth and rare earth ions, has been considered one of the most promising electrolyte materials for intermediate-temperature solid oxide fuel cells. It was found that doped ceria materials exhibit relatively high ionic conductivity under nonreducing conditions and relatively lower temperatures in comparison to that of YSZ electrolyte. Among the various dopants studied, Gd " and singly doped Sm ceria have been reported to have a high conductivity [8] and to be relatively stable in a reducing environment [49]. 

The electrolytic domain ti> 0.99) of doped ceria is limited at low PO2 due to the onset of electronic conductivity on reduction of Ce. The low p02 limit of the electrolytic domain depends on dopant type and doping level, and shifts to higher pOg with increasing temperature. The width of the electrolytic domain is maximized for 10-20 mol% Gd- or Sm-doped ceria, °° due to the optimized total ionic conductivity achieved in these compounds. The low pOg limit of these compounds shifts from ca. 10 atm at 400 °G and ca. 10" atm at 600 °C to ca. 10 atm at 800 For comparison, the... 

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