The lithium garnet has been considered as one of promising solid electrolytes for all solid state rechargeable lithium batteries. Under such circumstance, the Li₇La₃Zr₂O₁₂ (LLZO)-based powders and ceramics have been extensively studied in our lab. By elemental doping, liquid-phase sintering, atmosphere sintering, hot-pressing sintering technique and their combination, high-dense LLZO-based ceramics were obtained, showing the relative density above 99% and the ionic conductivity above 10^-3 S/cm at room temperature.

Based on these powders and dense ceramics, the solid electrolytes in form of hybrid membrane and thin plate were fabricated and used for the all solid state Li-ion and Li-air batteries. The batteries with LiFePO₄ or Li(NMC)O₂–based cathodes, the LLZO-based electrolytes and Li anodes exhibit good capacity and cycle performance. The Li-air batteries with the porous carbon-based air cathodes, the thin-plate electrolytes and Li anodes work for many cycles under ambient air, especially at elevated temperatures. In the presentation, the scientific and technical details for these batteries will be given. The fundamental issues and promising potential for application will be discussed.