Low-temperature synthesis of dense garnet-type Li6.5La3Zr1.5Ta0.5O12 layered structures using fluorite-type precursor oxide

Highlights: • A dense garnet-type solid electrolyte was synthesized at 700 ℃ using dense precursor oxide. • The thickness of the fabricated layers ranged from 15 to 500 µm. • The fabricated layer showed an electrical conductivity of 5.1 × 10⁻⁴ S·cm⁻¹ at room temperature. -- Abstract: We have fabricated a dense garnet-type Li-ion conductor at low temperature (700 °C) by allowing the dense precursor oxide La_0.6Zr_0.3Ta_0.1O_1.75 to react with the lithium vapor generated from the thermal decomposition of lithium nitrate. The obtained garnet-type Li_6.5La₃Zr_1.5Ta_0.5O₁₂ electrolyte layer had a columnar structure and its thickness was controlled within the range of 14 ~ 500 µm by adjusting the reaction temperature and time. The fabricated sample (500 µm) exhibited a total Li-ion conductivity of 5.1 × 10⁻⁴ S·cm⁻¹ at 25 °C and the temperature dependence of the Li-ion conductivity of the garnet-type Li-ion conductor was also investigated. Moreover, we were able to fabricate 30 µm thick dense free-standing Li_6.5La₃Zr_1.5Ta_0.5O₁₂ sheets using this precursor method.