Processing and Characterization of Bi2O3 and Sm2O3 Codoped CeO2 Electrolyte for Intermediate-Temperature Solid Oxide Fuel Cell

Abstract

A series of ceria-based solid solution electrolyte, Bi2O3 and Sm2O3 codoped CeO2 (Sm0.2−xBixCe0.8O1.9, x=0, 0.05, 0.10, 0.15, 0.20), were synthesized via a Pechini-type gel route. The phase composition was analyzed by the X-ray diffraction. Present study shows that Sm0.2−xBixCe0.8O1.9 is exceedingly stable as a cubic phase in all temperature range. Starting from the Sm0.2−xBixCe0.8O1.9 powder with specific surface area of 23.057 m2/g and using bismuth oxide as sintering aid, the sintering behavior investigation demonstrates that the Sm0.2−xBixCe0.8O1.9 green compacts can be densified to nearly theoretical density at 1300°C for 3 h. The very low sintering temperature prevents excessive grain growth during the heating, which is crucial for obtaining microcrystalline ceramics. In the temperature range of 500°–800°C, AC impedance spectra indicate that the Sm0.2−xBixCe0.8O1.9 has much higher ionic conductivity than SDC (Sm0.2Ce0.8O1.9), and that the highest conductivity value is 3.982 S/m at 750°C. The increased conductivity implies that the effect of cell volume and polarization, associated with Bi3+, played an important role in the anion transport of the materials.