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

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 wt% Li3BO3 composite sintered for 8 h at 1100 °C was 86.4% of the theoretical density, whereas the ionic conductivity was 1.94 × 10− 5 S cm− 1.