An improved synthesis method of ceria-carbonate based composite electrolytes for low-temperature SOFC fuel cells

•An improved freeze drying method was developed for SDC-carbonate nanocomposites.•The formation of lanthanide citrate complex gel is essential.•The carbonate content in SDC-carbonate can be precisely controlled.•Ionic conductivity of the SDC-carbonate was 0.4 S/cm at 600 °C.

SDC-carbonate composite electrolytes for low-temperature Solid Oxide Fuel Cells (LTSOFC) have been synthesized by an improved freeze drying method based on the formation of lanthanide citrate complex solution/gel. This method can not only maintain small particle sizes in composite, but also control the carbonate composition precisely. To optimize the electrochemical performance of the composite electrolytes, SDC-carbonate samples with different carbonate contents were prepared and investigated. SEM, EDS, MPD and XRD analyses were applied to characterize the morphology and carbonate content and EIS was used to determine the ionic conductivity of the electrolyte. The highest conductivity achieved was 400 mS/cm at 600 °C.