Development of electrode materials for solid oxide fuel cell

Abstract

Lanthanum strontium manganites (La1-xSrxMnO3) were extensively used as cathode materials for Solid Oxide Fuel Cell (SOFC). In this research, the effects of Co and Fe dopants with theamounts of 20 and 40 mol% were investigated on the properties of La0 84Sr0 16MnO3. This study concentrated on phase, crystal structure, electrical conductivity, microstructure and thermal expansion coefficient of these materials. All compositions in this work were prepared by conventional mixed-oxide process and sintered at 1450℃ The XRD results showed that the structure of undoped and Co-doped compositions were found to be monoclinic. In addition, the small amount of unknown second phases was observed in Co doped compositions after sintering. The electrical measurement indicated that the σ1000 C of 165 S cm-1 was the highest value obtained from undoped material. However, the conductivity at high temperature tended to increase with an amount of Co. The microstructures showed the decreasing of grain size as Co content increased. The thermal expansion coefficient tended to increased as Co content increased. For Fe substitution in Mn site, the monoclinic and the orthorhombic structures were found when the amount of Fe was 20 and 40 mol%, respectively. In addition, the sintered Fe-doped compositions contained high amount of second phases as detected by XRD. The σ₁₀₀₀C decreased and the grain size increased as Fe content increased. Their thermal expansion coefficients slightly changed with Fe addition.