LAUSR

Abstract The sintering and processing of garnet-type solid ceramic electrolytes (e.g., Li7La3Zr2O12 (LLZ)) are challenging because the material composition and microstructure at high temperatures must be carefully controlled to obtain the stabilization of highly conductive cubic phase and dense ceramic. Liquid-phase sintering using sintering aids is typically used for densifying ceramic materials, as it is a faster and/or lower-temperature process. In this study, we used solution-process-derived sintering additives to sinter garnet-type solid electrolytes highly effective in terms of relative density and properties at 1000 °C (10 h). The liquid phase formation during the sintering was rationalized to establish the optimal sintering conditions. The use of 1.2-vol% 75Li2O∙25B2O3 and 1.5-vol% Al2O3 as sintering additives was highly effective in densifying a Ta-doped LLZ, achieving a high ionic conductivity of 0.8 mS cm−1 (25 °C) with low activation energy (9 kJ mol−1) and almost negligible contribution of the grain boundary resistance (10 %).