Sintering behavior of garnet-type Li₇La₃Zr₂O₁₂-Li₃BO₃ composite solid electrolytes for all-solid-state lithium batteries

Abstract

In this study, Li₃BO₃ glass ceramic was utilized as a sintering additive for producing garnet-type Li₇La₃Zr₂O₁₂ solid electrolytes by low temperature sintering. The shrinkage and wetting behaviors of the Li₇La₃Zr₂O₁₂-Li₃BO₃ composite powder during heating were analyzed by dilatometry. The sintering shrinkage of the Li₇La₃Zr₂O₁₂-Li₃BO₃ composite powder occurred in two stages and was related to the densification of the composite. It was also closely related to the wetting behavior of the Li₃BO₃ glass. The sintering of Li₇La₃Zr₂O₁₂-Li₃BO₃ from around 700 °C is driven by the viscous sintering of Li₃BO₃ glass, while sintering above 850 °C is due to particle rearrangement in Li₇La₃Zr₂O₁₂ as well as the solid-state sintering of Li₇La₃Zr₂O₁₂ after the melting of Li₃BO₃. The density of the Li₇La₃Zr₂O₁₂-8 w Li₃BO₃ composite sintered for 8 hat 1100 °C was 86.4% of the theoretical density, whereas the ionic conductivity was 1.94 x 10⁻⁵ S cm⁻¹.