Low-Temperature Sintering of a Garnet-Type Li_6.5La₃Zr_1.5Ta_0.5O₁₂ Solid Electrolyte and an All-Solid-State Lithium-Ion Battery

Garnet-type Ta-substituted Li 7 La 3 Zr 2 O 12 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 °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 Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZT) solid electrolyte at a remarkably low temperature of 400 °C was demonstrated using the submicrometer-sized garnet-type LLZT fine powder sample prepared at 600 °C through a reaction of Li 2 O and La 2.4 Zr 1.2 Ta 0.4 O 7 . The lithium-ion conductivity at 25 °C was 4.54 × 10 –5 S cm –1 without any additives through low-temperature sintering at 400 °C. In addition, the preliminary battery performance of the oxide-based all-solid-state LiNi 1/3 Co 1/3 Mn 1/3 O 2 –Li 4 Ti 5 O 12 full-battery cell fabricated at 400 °C using the present LLZT fine powder sample as the solid electrolyte was demonstrated.