Phase stability and electrochemical performance of Y0.5Ca0.5−xInxBaCo3.2Ga0.8O7+δ (x = 0 and 0.1) as cathodes for intermediate temperature solid oxide fuel cells

Y0.5Ca0.5−xInxBaCo3.2Ga0.8O7+δ (x = 0.0 or 0.1, and denoted as YCBCG, YCIBCG, respectively) oxides are synthesized and investigated as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). The In content (x) significantly affects the properties of Y0.5Ca0.5−xInxBaCo3.2Ga0.8O7+δ. The YCIBCG oxide exhibit superior phase stability compared to YCBCG at high temperatures (700-950 °C). The substitution of In for Ca improves the long-term phase stability at higher temperatures, but slightly degrades the electrochemical performance. Thermal expansion coefficient (TEC) values of the YCBCG and YCIBCG oxides are 9.8 × 10−6 K−1and 9.7 × 10−6 K−1 in the range of 30-850 °C, respectively, which provides good mechanical compatibility with the electrolyte (10.9 × 10−6 K−1 for LSGM). The interfacial polarization resistances for YCBCG and YCIBCG cathode are as low as 0.140 Ω cm2 and 0.146 Ω cm2 at 700 °C, respectively. The maximum power densities of the NiO-SDC/SDC/LSGM/YCBCG and NiO-SDC/SDC/LSGM/YCIBCG cells are 434 and 415 mW cm−2 at 800 °C, respectively with a 300 μm thick electrolyte. The results of this study demonstrate that YCBCG and YCIBCG are very promising cathode materials for intermediate temperature SOFCs.