High Li-ion conductivity of Al-doped Li7La3Zr2O12 synthesized by solid-state reaction

Li 7 La 3 Zr 2 O 12 (LLZO) has cubic garnet type structure and is a promising solid electrolyte for next-generation Li-ion batteries. In this work, Al-doped LLZO was prepared via conventional solid-state reaction. The effects of sintering temperature and Al doping content on the structure and Li-ion conductivity of LLZO were investigated. The phase composition of the products was confirmed to be cubic LLZO via XRD . The morphology and chemical composition of calcined powders were investigated with SEM, EDS , and TEM . The Li-ion conductivity was measured by AC impedance. The results indicated the optimum sintering temperature range is 800–950   °C, the appropriate molar ratio of LiOH·H 2 O, La(OH) 3 , ZrO 2 and Al 2 O 3 is 7.7:3:2:(0.2–0.4), and the Li-ion conductivity of LLZO sintered at 900   °C with 0.3   mol of Al-doped was 2.11×10 −4   S   cm −1 at 25   °C.