Compatibility and performance of La0.675Sr0.325Sc0.99Al0.01O3 perovskite-type oxide as an electrolyte material for SOFCs

Abstract

Sr2+, Al3+-doped LaScO3 perovskite-type oxide (La0.675Sr0.325Sc0.99Al0.01O3; LSSA), which exhibits high conductivity of both oxide-ion and proton, is expected to become an electrolyte material for high-temperature solid oxide fuel cells (SOFCs). Considering the potential of this material to serve as a solid electrolyte, its chemical compatibility with some of the typical fuel electrodes commonly used in SOFCs was investigated. Severe elemental diffusion was found at the sintering temperature of 1673 K between doped LaScO3 and the anode material, mainly due to strontium migration. To control the elemental diffusion, we lowered the sintering temperature to 1523 K. In the case of Ni-SDC, we found no elemental diffusion at the electrolyte/electrode interface. Moreover, we tried to fabricate SOFC consisting of LSSA electrolyte and some electrodes, and we performed power generation tests above 1073 K. At 1273 K, the maximum power density was 158 mW cm-2 as humidified hydrogen fuel. The electrolyte resistance was high due to the high thickness of 0.6-0.9 mm. Higher power density would seem possible if a thinner electrolyte is applied. Consequently, we found that LSSA is applicable as an electrolyte material for SOFCs.