Low-Temperature Sintering of a Garnet-Type Li6.5La3Zr1.5Ta0.5O12 Solid Electrolyte and an All-Solid-State Lithium-Ion Battery

Garnet-type Ta-substituted Li7La3Zr2O12 materials attract considerable attention as solid electrolytes for use in future oxide-based all-solid-state lithium-ion batteries owing to their superior ionic conductivity and chemical and electrochemical stabilities. However, high-temperature sintering above 1000 degrees C, which is needed to realize high lithium-ion conductivity, results in the formation of insulating interface impurities at the electrode- electrolyte interface. Herein, the low-temperature sintering of the Li6.5La3Zr1.5Ta0.5O12 (LLZT) solid electrolyte at a remarkably low temperature of 400 degrees C was demonstrated using the submicrometer-sized garnet-type LLZT fine powder sample prepared at 600 degrees C through a reaction of Li2O and La2.4Zr1.2Ta0.4O7. The lithium-ion conductivity at 25 degrees C was 4.54 x 10-5 S cm-1 without any additives through low-temperature sintering at 400 degrees C. In addition, the preliminary battery performance of the oxide-based all -solidstate LiNi1/3Co1/3Mn1/3O2-Li4Ti5O12 full-battery cell fabricated at 400 degrees C using the present LLZT fine powder sample as the solid electrolyte was demonstrated.