Densification of Sm0.2Ce0.8O1.9 with the addition of lithium oxide as sintering aid

► The maximum shrinkage rate of SDC was about 0.4% of that of SDC2. ► Three regions could be divided during SDC2 sintering. ► The activation energy of SDC2 was 5.54 ± 0.50 eV because of a liquid phase in grain boundary. ► The grain boundary diffusion dominant densification with 4.2 × 10−17 m3 N−1 s−1 at 900 °C. ► The OCV of the cell using SDC2 as electrolyte is 0.78 V at 600 °C.