Processing and characterization of novel Ce0.8Sm0.1Bi0.1O2-δ-BaCe0.8Sm0.1Bi0.1O3-δ (BiSDC-BCSBi) composite electrolytes for intermediate-temperature solid oxide fuel cells

Abstract Ce0.8Sm0.1Bi0.1O2-δ-BaCe0.8Sm0.1Bi0.1O3-δ (BiSDC-BCSBi) composites are fabricated as novel electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Both dramatically enhanced sinterability and electrical performance are obtained due to the Bi doping. BiSDC-BCSBi composites are densified at as low as 1200 °C, allowing a decrease of 350 °C compared with Ce0.8Sm0.2O2-δ-BaCe0.8Sm0.2O3-δ (SDC-BCS) composites. The optimal electrical conductivity of BiSDC-BCSBi electrolytes measured at 600 °C in humid air reaches up to 27.97 mS cm−1, almost 6 times higher than that of SDC-BCS electrolytes (3.91 mS cm−1 in humid air), which is mainly attributed to their lower sintering temperature, more uniform microstructure, larger tensile strains, and higher concentrations of O–H groups and oxygen vacancies. The electrolyte-supported single cell with BiSDC-BCSBi electrolyte displays a peak power density of 397 mW cm−2 at 600 °C using humid hydrogen as fuel and ambient air as oxidant. These results imply that BiSDC-BCSBi composites have a great application prospect for IT-SOFCs.