Method Using Water-Based Solvent to Prepare Li 7 La 3 Zr 2 O 12 Solid Electrolytes.

Li-Garnet Li7La3Zr2O12 (LLZO) is a promising candidate for high safety solid-state Li+ ion batteries. However, due to its high reactivity to water, the preparation of LLZO powders and ceramics is not easy for large-scale amounts. Herein a method applying water-based solvent is proposed to demonstrate a possible solution. Ta doped LLZO, ie, Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and its LLZTO/MgO composite ceramics are made by attrition milling followed by spray-drying process using water-based slurries. The impacts of parameters of the method on the structure and properties of green and sintered pellets are studied. Relative density of ~95%, Li-ion conductivity of ~3.5×10-4 S/cm and uniform grain size LLZTO/MgO garnet composite ceramics are obtained with an attrition milled LLZTO/MgO slurry that contains 40 wt% solids, and 2 wt% polyvinyl alcohol (PVA) binder. Li-Sulfur batteries based on these ceramics are fabricated and work under 25°C for 20 cycles with a Coulombic efficiency of 100%. This research demonstrates a promising mass production method for the preparation of Li-garnet ceramics.