Effect of Sr and Mg Doping on the Property and Performance of the La[sub 1−x]Sr[sub x]Ga[sub 1−y]Mg[sub y]O[sub 3−δ] Electrolyte

(LSGM) with various and levels were prepared and evaluated as a solid oxide fuel cell electrolyte. The electrical conductivity of LSGM was dramatically enhanced with the increase of both the Sr and Mg doping levels. The compositions with Sr and Mg were found to possess much higher conductivity than the other compositions at . The optimal composition was with the highest conductivity of 0.177 and at 800 and , respectively. The coefficient of thermal expansion (CTE) was measured and shrinkage probably due to phase transition was observed in the CTE curve. The correlation between the phase transition, thermal expansion, and electrical conductivity was discussed. The performance of various LSGM compositions was assessed through the electrolyte-supported cells using a anode over a LDC buffer layer and a (SCF) cathode. The single cell with the electrolyte gave the best performance among all the cells, i.e., a maximum power density of 1.23 and in wet at 800 and , respectively. A relatively stable cell performance with loss in power density was observed over under a constant current density of at . The power loss was mainly due to the increase in cathode overpotential. Co was found to diffuse across the interface from the SCF cathode into the LSGM electrolyte during the long-term testing, which might lead to a Co deficiency in the cathode and thus contribute to the observed degradation in the cathode as well as the cell performance.