Solid Oxide Fuel Cells Using Novel Cathodes in the BaO-Co2O3-Fe2O3 Composited withGDC10

Abstract

Most current cathodes for SOFCs such as LSM, LSC and LSCF contain lanthanum oxide. The tendency for the lanthanum oxide to absorb moisture and degrade the materials make processing a critical issue. In this study, we have explored the fabrication of cathode materials free from lanthanum oxide. Compositions with high electrical conductivity in BaO-Y2O3-Fe2O3 and BaO-Y2O3-Co2O3-Fe2O3 systems have been obtained. Selected compositions with high electrical conductivities up to 600Scm-1 have been composited with GDC10 solid oxide electrolyte to form composite cathodes with matching thermal expansion to GDC10 for solid oxide fuel cells(SOFCs). Symmetrical cells with GDC10 between the experimental composite cathodes, and small SOFCs with GDC10 as electrolyte, GDC10.NiO as anode and experimental composites as cathodes have been constructed and evaluated up to 800oC. The electrical conductivity, thermal expansion, impedance and power densities have been studied. The power densities between 400oC and 800oC have been measured. The power density obtained at 800oC is found to be about 600mW/cm2. The results are presented and discussed in relation to the processing of the materials, properties, microstructures and performance of the solid oxide fuel cell. Ways to enhance the performance of the SOFCs are highlighted.