Lanthanum chromite anodes

Kobsiriphat W et al (2010) Nickel- and ruthenium-doped lanthanum chromite anodes effects of nanoscale metal precipitation on solid oxide fuel cell performance. J Electrochem Soc 157 B279... 

The anode material in SOF(7s is a cermet (rnetal/cerarnic composite material) of 30 to 40 percent nickel in zirconia, and the cathode is lanthanum rnanganite 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. 

J. Sfeir, P A. Buffat, P. Mockli, N. Xanthopoulos, R. Vasquez, H. J. Mathieu, J. Van herle, and K. Ravindranathan Thampi, Lanthanum chromite based catalysts for oxidation of methane directly on SOFC anode, J. Catal. 202, 229-244 (2001). 

A.-L. Sauvet, J. Fouletier, F. Gaillard, M. Primet, Doped lanthanum chromites as SOFC anode materials , Journal of Catalysis 209[1],25-34 (2002). 

The lanthanum chromite interconnect strip is applied along the length of the tube by plasma-spraying. Since this is required to pass through the electrolyte and anode it is necessary to use appropriate masking during their deposition. The connection between cells is made via a soft nickel felt so that no dangerous mechanical stresses are placed on the tubes. 

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,...

Sfeir J, Buffat PA, Mockli P, Xanthopoulos N, Vasquez R, Mathieu HJ, Van herle J, Thampi KR (2001) Lanthanum chromite based catalysts for oxidation of methane directly on SOFC anodes. J Catal 202 229-244... 

Vemoux P, Djurado E, Guillodo M (2001) Catalytic and electrochemical properties of doped lanthanum chromites as new anode materials for solid oxide fuel cells. J Am Ceram Soc 84 2289-2295... 

The cell interconnect (doped lanthanum chromite) must be impervious to fuel and oxidant gases, and must possess good electronic conductivity. The interconnect is exposed to both the cathode and anode environments. Thus, it must be chemically stable under O2 partial pressures of about 1 to 10 atmospheres at 1,000 °C. The interconnect material is applied to the cathode tube as a narrow strip (see Figure 7-9, Figure 7-11) prior to depositing the electrolyte by masking the rest of the tube. Similarly, the interconnect strip is masked when the electrolyte is applied. 

For perovskite-based fuel electrodes, Mn-doped lanthanum strontium chromite (Lao.75Sro25Mno.5Cro.5O3, LSCM), developed by Tao and Irvine, has been infiltrated with ceria-based materials by other research groups, who reported that an improved electrocata-lytic activity was achieved when tested with various fuels. " Without infiltration of a ceria phase into LSCM-YSZ anodes, the oxidation of methane was considered to be limited by insufficient oxygen ion conductivity in the lanthanum chromite-based materials. Gd-doped ceria has higher oxide ion conductivity than LSCM, which is also illustrated by an improved performance of these infiltrated electrodes. The mechanism of methane oxidation in Gd-doped ceria-infiltrated LSCM anodes in wet CH4 was considered to involve the partial oxidation of methane by a gas/solid reaction between ceria and methane-generating CO and H2, followed by electrochemical oxidation of the products. The added ceria also suppressed coke formation in these anodes. ... 

Doped ceria and doped lanthanum chromites were investigated a long time ago because ceria is a mixed conductor in a reducing atmosphere, whereas lanthanum chromites are typical candidates for oxide interconnects. Neither of the materials shows good performance as an anode. In recent years, other types of perovskite oxides have attracted attention, as is described in other chapters of this book. The basic trade-off relationship associated with oxide anodes is stability versus performance. 

Sfeir J, van Herle J, McEvoy AJ. (1999). Stability of calcium substituted lanthanum chromites used as SOFC anodes for methane oxidation. J Eur Ceram Soc. 19, 897-902. 

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