Synthesis and electrical properties of screen-printed doped ceria interlayer for IT-SOFC applications

In this paper, four types of doped ceria powders and sinters, including Gd0.1Ce0.9O1.95, Gd0.2Ce0.8O1.9, Sm0.1Ce0.9O1.95 and Sm0.2Ce0.8O1.9, are prepared and characterized. The results indicate that the Sm0.2Ce0.8O1.9 samples possess the lowest densification temperature and a relatively optimal conductivity, which make it more suitable for use as an interlayer compared to other doped ceria. In addition, a series of interlayers were prepared from Sm0.2Ce0.8O1.9 powders with different precalcination temperatures using an industrial screen printing method. The area-specific resistances of these interlayers were determined from their microstructures, including the grain and pore size, electrolyte/interlayer interface, layer uniformity and density, which are significantly dependent on the precalcination temperatures of the powders. A minimum area-specific resistance of 0.036 Ω cm2 at 750 °C was obtained for the sample with Sm0.2Ce0.8O1.9 powders precalcined at 950 °C (the corresponding BET value was approximately 20 m2 g−1). In addition, lanthanum strontium cobalt ferrite (LSCF) cells were prepared with the as-prepared Sm0.2Ce0.8O1.9 interlayer. Their power density was measured and determined to be 0.72 W cm−2 at 750 °C (0.75 V, active area of 64 cm2).