Lanthanum manganite cathodes

Fig. 2 Schematic of SOFC operation presenting the four-step anodic. H2O formation and electron transfer were shown in the insert. LSM strontium-doped lanthanum manganite (cathode for SOFC), Vq" vacancy of oxygen...

In the tubular SOFC, as illustrated by the Siemens Westinghouse design shown in Fig. 13 [86], the cell components are deposited in the form of thin layers on a doped lanthanum manganite cathode tube [80, 87]. The cathode tube (2.2 cm diameter,... 

Figure 4.19 Typical polarization curves for high-temperature SOFC in different gas environments at 1000° C. The high operating temperature enables the use of low-cost catalyst materials such as nickel (anode) and strontium-doped lanthanum manganite (cathode), with very low kinetic polarization losses. (Reproduced with permission from [5].)...

Similar problems are also encountered for cathodes and interconnects which are complex oxides of rare earths and transition metals. For the cathode supported tubular type SOFCs, the cost of lanthanum manganite cathode is very important because it is a large fraction of the total cell capacity. 

Cathode Porous Pt Stabilized Zr02 impregnated with praesodymium oxide and covered with SnO doped In203 Doped lanthanum manganite Extrusion, sintering 2 mm thickness 11 X 10 cm/cm°C expansion from room temperature to 1000°C 30-40% porosity... 

Fig. 13.22. The monolithic SOFC concept of Argonne National Laboratory. Anode nickel-yttria-stabilized zirconia. Cathode strontium-doped lanthanum manganite. Interconnect doped lanthanum chromite, a, Interconnection b, electron-ion path c, anode d, electrolyte e, cathode. (Reprinted from K. Kordesch,...

The anode material in SOFCs is a cermet (metal/ceramic composite material) of 30 to 40 percent nickel in zirconia, and the cathode is lanthanum manganite doped with calcium oxide or strontium oxide. Both of these materials are porous and mixed ionic/electronic conductors. The bipolar separator typically is doped lanthanum chromite, but a metal can be used in cells operating below 1073 K (1472°F). The bipolar plate materials are dense and electronically conductive. 

Electrodes The anodes of SOFC consist of Ni cermet, a composite of metallic Ni and YSZ, Ni provides the high electrical conductivity and catalytic activity, zirconia provides the mechanical, thermal, and chemical stability. In addition, it confers to the anode the same expansion coefficient of the electrolyte and renders compatible anode and electrolyte. The electrical conductivity of such anodes is predominantly electronic. Figure 14 shows the three-phase boundary at the interface porous anode YSZ and the reactions which take place. The cathode of the SOFC consists of mixed conductive oxides with perovskite crystalline structure. Sr doped lanthanum manganite is mostly used, it is a good /7-type conductor and can contain noble metals. 

Key words X-ray Absorption Spectra/3d-Transition Metal Oxides/SOFS-Cathodes MaterialsA alence State/Doped Lanthanum Manganite... 

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. 

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. 

Strontium-doped lanthanum manganite synthesis for solid oxide fuel cells cathode. Journal of New Materials for Electrochemical Systems, Vol. 12, No. 2-3, (1 April 2009), pp. (109-113), ISSN 1480-2422... 

Endo, A., Ihara, M., Komiyama, H., and Yamada, K. (1996). Cathodic reaction mechanism for dense Sr-doped lanthanum manganite electrodes. Solid State Ionics 86-88 ... 

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