Lanthanum cobaltite cathodes

Single-phase perovskite MIECs such as Sr-doped lanthanum cobaltite (LSC), lanthanum ferrite (LSF), lanthanum cobalt ferrite (LSCF) and samarium cobaltite (SSC), and Ca-doped lanthanum ferrite (LCF) [13] are sometimes used alone in SOFC cathodes, as depicted in the lower right-hand comer of Figure 6.1, but combining an... 

The cathodes consist of manganites or cobaltites of lanthanum doped with divalent metal ions, for example, Lai (Srj(Mn03 (LSM) or Lax (Srj(Co03 (LSC), where 0.15 cathode materials also have some electronic conductivity that secures a uniform current distribution over the entire electrode. The doped lanthanum cobaltite has a higher ionic conductivity than the doped lanthanum manganite, but is more expensive and leads to problems, in particular on account of a possible chemical interaction with the electrolyte. 

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. 

Cathodes present the main electrode issues in designing and operating SOFCs, as described in Chapter 5. Since these operate in a highly oxidising environment, it is not possible to use base metals and the use of noble metals is cost prohibitive. Consequently, semiconducting oxides have been the most prominent candidates since 1966 when doped lanthanum cobaltites began to be used, followed in... 

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. 

The simple method of shortcut determination of a transitional metals charge state in mixed-valence compounds which are applied as SOFC cathode materials is tested. The standard X-ray diffractometers which are present in the majority material-sciency laboratories are used for this purpose. The offered method is applied at the research of 3d-metals valency in some lanthanum manganites, nickelites and cobaltites. As the measurement standards the metals and their oxides were used. 

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. 

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