UNIDEF   23986
UNIDAD DE INVESTIGACION Y DESARROLLO ESTRATEGICO PARA LA DEFENSA
Unidad Ejecutora - UE
artículos
Título:
Correlation between Structural, Chemical and Electrochemical Properties of La0.6Sr0.4CoO3-d Nanopowders for Application in Intermediate Temperature Solid Oxide Fuel Cells
Autor/es:
ACUÑA L. M.; MUÑOZ F.F.; FUENTES, R. O.
Revista:
JOURNAL OF PHYSICAL CHEMISTRY C
Editorial:
AMER CHEMICAL SOC
Referencias:
Lugar: Washington; Año: 2016 vol. 120 p. 20387 - 20399
ISSN:
1932-7447
Resumen:
Lanthanum-Strontium cobaltites are excellentmixed ionic and electronic conductors and exhibit a good activity for theoxygen reduction reaction (ORR) at temperatures higher than 500°C. This led topropose these materials as cathode for solid-oxide fuel cell devices, either forthe standard high temperature (SOFC, 900?1000°C) or the intermediatetemperature (IT-SOFC, 500?700°C) range. Although it was determined that crystalstructure and oxygen vacancies play a central role in these properties, littleis known about cobalt speciation at SOFC or IT-SOFC working temperatures. Inthis study is analyzed in detail for the first time the cobalt speciation andlocal order of La0.6Sr0.4CoO3-d (LSC) nano-and microstructured powders by means of insitu experiments using X-ray spectroscopy (XAS) in the temperature range of20?700°C. It is also studied the electrochemical performance of LSC-basedcathodes in symmetrical cells under the same conditions using theelectrochemical impedance spectroscopy (EIS). Cobalt atomscan be found in any of the three possible oxidation states. Their relativeamount depends on temperature and crystallite size. In crystallites of few tensof nanometers, the easy of Co atoms for changing its oxidation state isenhanced. This feature probably prompts the oxide transport in LSC-basedcathodes.