Lanthanum strontium cobaltite

The oxygen electrode of the cells under analyses in our project is a perovskite material Ao.8Sr0.2Mn03 (element A is not disclosed because it is proprietary information). Scandia-stabilised zirconia (SSZ) is used as the electrolyte. The cathode consists of a Ni-SSZ cermet. Also, a lanthanum strontium cobaltite (La0.8Sr0.2CoO3, also known as LSC) is used as the bond layer. 

An ideal membrane must have high electronic and protonic conductivities it should be fairly thin (1-10 pm), and chemically stable for prolonged periods of time under the presence of various gases such as CO2, H2O and H2S etc. The low electronic conductivity limits the H2 flux of the protonceramic membranes. Under pure H2 atmosphere at 900 "C, the protonic conductivities of SCYb and BCNd are about 0.7 x 10 2 and 2.2 x 10 2 S cm , respectively. These values are sh tly lower than the oxygen ionic conductivity of yttria stabilized zirconia (YSZ) or lanthanum strontium cobaltite (LSC) perovskite-type ceramics in air at the same temperature, so that there is room for further improvement in protonic conductivity. 

Since it was known that the use of a PVD-appIied CGO layer resulted in a significant improvement in the electrochemical performance, the next step was to optimize further the electrochemical properties of the cathode layer. A first screening test was based on the use of Lao.58Sro.4oCoi.o03 j [lanthanum strontium cobaltite (LSC)] as the cathode. Regarding this type of perovskite, it should be taken into account that the TEC of this material (about 23 x 10 " is much higher than that of 8YSZ, which lies around 11-12 x lO" [25]. Such a TEC mismatch will probably... 

In many cases, achievement of reliability is in trade-off relation to cost reduction. To overcome this, it is required to make breakthroughs in the fabrication technologies. Cells to be operated in the temperature region of around 800°C. Metal intercoruiects are used together with anode-support cells and sealing materials. The active cathode such as LSCF (lanthanum strontium cobaltite ferrites) is used so that the durability is one of the main issues. 

Table 18.2 Comparison of cathodes among lanthanum strontium manganites, ferrites, and cobaltites in their chemical reactivity, functionality as cathode, and tolerance against Cr poisoning...

Y. Denos, F. Morin and G. Trudel, Oxygen diffusivity in strontium substituted lanthanum cobaltite, in T.A. Ramanarayanan, W.L. Worrel and H.L. Tuller (Eds.), Proceedings of the 2nd International Symposium on Ionic and Mixed Conducting Oxide Ceramics. The Electrochemical Society, Pennington, NJ, 1994, pp. 150-158. 

Faaland S, Einarsmd MA, Grande T. Reactions between calcium and strontium substituted lanthanum cobaltite ceramic membranes and calcium silicate sealing materials. Chem Mater. 2001 13 723. 

To ensure good contact resistance (primarily with the cathode) and minimize evaporation of chromia, many developers use interconnect coatings of strontium-doped lanthanum cobaltite or manganite, which have proven effective for at least several thousand hours. 

Deng,J. Zhang,L. Dai, H. et al. Strontium-doped lanthanum cobaltite and manganite highly active catalysts for toluene complete oxidation. Ind. Eng. Chem. Res. 2008, 47, 8175-8183. 

Magnone, E., Traversa, E. and Miyayama, M. (2005), Synthesis and characterization of strontium and iron-doped lanthanum cobaltite nanocrystaline powders for single chamber solid oxiite fuel cells. Ninth International Symposium on Solid Oxide Fuel Cells (SOFC-IX), Eds. S.C. Singhal and J. Mizusaki, pp. 1617-1626. The Electrochemical Soc. Inc., Pennington, NJ, USA. 

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