In Situ Studies on the Catalytic and Electronic Properties of Multi-Dimensional Cathode

[摘要] The overall objective of this program was to provide the fundamental background to enable SECA Industrial Team Members to select and develop oxide cathodes for the operation of solid oxide fuel cells in the intermediate temperature (500-700 C). A number of experimental techniques were used to address the specific obstacles within the program. The work expanded our existing experimental techniques to the use of in situ diffraction and spectroscopic techniques that are sensitive to the oxygen and iron structural and chemical environment. Such measurements were coupled with the evaluation and determination of the catalytic properties of potential cathode oxides. The scope of the work was to prepare carefully controlled cathode samples of various compositions and microstructure and perform fundamental measurements of their physical properties. The measurement of physical properties of the cathode materials systems were used to correlate those properties to the overall effectiveness of the material as a constituent of an SOFC cell. The measurements techniques of neutron scattering and Moessbauer are relatively unique capabilities which have significance to the LSCF cathode system. The unique ability to make thin film samples can provide special samples for surface science efforts to understand cathodic catalytic activity. The data obtained from neutron diffraction, Moessbauer Spectroscopy, electrical measurements and modeling show that the oxygen vacancy content at 500 C in air for La{sub 0.8}Sr{sub 0.2}MnO{sub 3}, La{sub 0.6}Sr{sub 0.4}FeO{sub 3} and La{sub 0.6}Sr{sub 0.4}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} are 0, 1% and 5% respectively. This is a significant finding that should relate to performance as a cathode, and gives criteria for the selection of new cathode materials.

[发布日期] 2003-12-01 [发布机构] University of Missouri--Rolla

[关键词] Cathodes;Oxygen;Neutron Diffraction;30 Direct Energy Conversion;Oxides