Lanthanum gallate-based electrolytes

In this chapter, the key competences of our technology toward the development of commercial SOFC power generation units utilizing cation-doped lanthanum gallate-based electrolyte are summarized. 

Marko Hrovat, Ariane Ahmad-Khanlou, Zoran Samadzija, Janez Hole, Interactions between lanthanum gallate based solid electrolyte and ceria , Materials Research Bulletin, 34[12/13], 2027-2034 (1999). 

Lanthanum gallate-based perovskite oxide is selected as the electrolyte material for high-performance cells. Strontium is used as a dopant to the A site, and magnesium together with cobalt are doped to the B site of the... 

An alternative approach to reduce the operating temperature is to use new electrolyte materials such as scandium doped zirconia (SeSZ), and rare earth doped ceria (RDC) which have the fluorite type stmeture, or lanthanum gallate based oxides such as (La,Sr)(Ga,Mg)03 (LSGM) with perovskite stmeture, all of which have higher ionic conductivities than YSZ. An 1 kW class SOFC stack with (La,Sr)(Ga,Mg,Co)03 electrolyte was demonstrated by the collaboration of Mitsubishi Materials Corp. and The Kansai Electric Power Co., Inc. in 2001,... 

Lanthanum gallate is doped with divalent metal ions, for instance, strontium and magnesium Lai jSrjMgyGai j,03 usually, x and y have values between 1 and 0. Unlike the ceria-based electrolytes, this electrolyte can also be used at low oxygen partial pressures without the menace of developing an electronic conductivity. When in contact with cathodes of the LSM- or LSC type, some diffusion of manganese and cobalt from the cathode into the electrolyte is possible, but this has little effect on the fuel cell s performance. A certain defect of this electrolyte material is its complicated preparation procedure. 

T. Inagaki, F. Nishiwaki, S. Yamasaki, T. Akbay and K. Hosoi, Intermediate Temperature Solid Oxide Fuel Cell based on Lanthanum Gallate Electrolyte,/. Power Sources, 181,274-280(2008). 

The final class of conventional electrolyte is based upon the perovskite structured (ABO3) lanthanum gallate (Figure 2.3). Ishihara et and Huang et both reported in the 1990s fast oxide ion conduc-... 

Reactions (3) and (4) proceed in solid electrolytes, for instance, in solid solutions based on lanthanum gallate of the general formula Lai.xAxGai.yBy03.(x+yy2(A = Ca, Sr, Ba B = Mg, Zn). These systems have high ionic conductivity caused by high concentration of oxygen vacancies [14, 15] and they are wide gap semiconductors, hence, concentrations of intrinsic electronic defects in these compounds are very low. 

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