Deeper Understanding of Ternary Eutectic Carbonates/Ceria-Based Oxide Composite Electrolyte through Thermal Cycling

Due to a high conductivity of about 0.1 S·cm−1, Li-Na-K carbonate eutectic and Sm-doped ceria composite material is good electrolyte candidate for hybrid fuel cells operating between 500 °C 600 °C. The present paper aims at deeper understanding the species mechanisms involved in ionic transport through impedance spectroscopy thermal analyses, oxidizing reducing atmospheres, wet dry, during two heating/cooling cycles. Complementary structural analyses post-mortem phases allowed us evidence irreversible partial transformation molten carbonates into hydrogenated species, when water and/or hydrogen are added surrounding atmospheres. Furthermore, this modification was avoided by adding CO2 anodic cathodic compartments. Finally, mechanistic model such electrical behavior suggested, according atmospheres used. It leads conclusions that based on kind would preferably operate cell conditions, than solid oxide confirms name “Hybrid Fuel Cells” instead Intermediate Temperature (or even Low Temperature) Solid Oxide Cells.