Effect of Ca2+ and Sr2+ doping on the microstructure and cell performance of samaria-doped ceria electrolytes used in solid oxide fuel cells

• S15C05DC is a better choice than S15S05DC in the electrolyte materials.
• The power density of S15C05DC electrolyte-supported cell is 213 mW cm−2.
• Maximum densification strain rate of S15C05DC is 10.6–11.1 × 10−3 min−1 at 1330 °C.
• Addition of Ca or Sr ion can act as an aid for accelerating CeO2 sintering.
• The diffuse scattering of SAED patterns are more clearly observed in S15C05DC.

Ce0.8Sm0.15Ca0.05O1.875 (S15C05DC) and Ce0.8Sm0.15Sr0.05O1.875 (S15S05DC) electrolytes were synthesized by a solid-state reaction and used to prepare solid oxide fuel cells. The microstructures and electrical properties of the electrolytes were analyzed by XRD, SEM, thermal analyzer, thermomechanical analysis, TEM, electrochemical analysis, and impedance spectroscopy. The maximum densification strain rates of S15C05DC and S15S05DC were 10.6 × 10−3–11.1 × 10−3 min−1 at 1330 °C and 8.3 × 10−3–8.7 × 10−3 min−1 at 1300 °C, respectively. The addition of Ca2+ or Sr2+ could help in accelerating CeO2 sintering. The maximum open-circuit voltages and power densities of La0.6Sr0.4Co0.2Fe0.8O3−δ/S15C05DC/Ce0.8Sm0.2O1.9-Ni (cell I) and La0.6Sr0.4Co0.2Fe0.8O3−δ/S15S05DC/Ce0.8Sm0.2O1.9-Ni (cell II) were 0.72 V and 213 mW cm−2 and 0.71 V and 173 mW cm−2, respectively, at 800 °C. The ohmic resistances of cells I and II are 0.443 and 0.505 Ω cm2, respectively, at 800 °C. The conclusion is that S15C05DC is a better choice than S15S05DC in the electrolyte materials.