Preparation of LaGaO3 thin film for intermediate temperature SOFC by screen printing method (I)

Abstract

La-doped ceria (Ce0.6La0.4O1.8 [LDC]) has been reported to be an effective buffer layer material for preventing the chemical reaction between Sr- and Mg-doped LaGaO3 (LSGM) electrolyte and Ni-based anode during sintering. However, it seems difficult to achieve a high power density on the cell using LDC buffer layer because of its low sintering and electrical conducting properties. In this study, effects of various sintering additives such as MgO, SrO, In2O3, Ga2O3, ZrO2, and LSGM oxide powders were studied for improving sintering density and electrical conductivity of LDC. Sintering property, phase formation, and electrical conductivity varied with the sintering agents. Addition of SrO, Ga2O3, or LSGM enhanced the sintering density of LDC while LSGM addition was effective to increase the electrical conductivity. LSGM sintering aid was inert with LDC accompanying no chemical reaction after sintering at 1,623 K. Therefore, it was considered that a small amount of LSGM addition as a sintering agent was desirable for improving sintering and electrical properties of LDC. Furthermore, a single cell using LSGM-added LDC buffer layer and LSGM electrolyte film was fabricated by a screen printing method after co-firing at 1,623 K. The obtained cell showed an almost theoretical open circuit voltage and a high maximum power density (0.725 W cm−2) at 973 K.