Investigation of Li Dopant as a Sintering Aid for ScSZ Electrolyte for IT-SOFC

In this study, the effects of small amounts (≤3 mol%) of Li doping on the sintering characteristics and electrochemical performance of (ZrO₂) 0.89 (ScO 1.5 ) 0.1 (CeO₂) 0.01 (ScSZ) were investigated. By adding 3 mol% lithium, the densification temperature of ScSZ was reduced from the conventional temperature of 1400℃ to 1200℃. It was found that Li doping also led to changes in the Zr:Sc ratio at the grain boundaries. Correspondingly, the dispersion of lithium zirconia at the grain boundaries accelerated the growth of ScSZ grains and increased the grain boundary resistance at temperatures below 450℃. At elevated temperatures of 450~750℃, the electrical conductivity of the ScSZ after doping remained almost unchanged under air and reducing atmospheres. These results suggest that the addition of lithium is promising for use in low temperature co-firing of ScSZ-based components for intermediate temperature solid oxide fuel cells.