One-step low-temperature synthesis of Li 0.33 La 0.55 TiO 3 solid electrolytes by tape casting method

Li0.33La0.55TiO3 (LLTO) is a solid Li-ion conductor with high bulk ionic conductivity. However, a high processing temperature, typically around 1300 °C, is generally required for obtaining its crystallization. In this work, LLTO was successfully synthesized at temperatures as low as 900 °C by tape casting method. Thermogravimetric analysis was carried out on the precursors for clarifying the weight loss and related phase transformations, and powder X-ray diffraction analysis was performed on the final products for verifying the crystallinity and phase purity in the low-temperature-processed LLTO electrolytes. The morphology of the synthesized LLTO powders was observed by scanning electron microscopy for understanding the microstructural evolution with increase of the sintering temperature. The ionic conductivity and activation energy of LLTO solid electrolytes were measured. A typical ionic conducting behavior with a moderate total conductivity of 4.3 × 10−6 S/cm and a quite low activation energy of 0.29 eV was obtained in the 900 °C-derived LLTO sample. When the processing temperature was raised to 1350 °C, the total ionic conductivity was further enhanced, reaching 6.13 × 10−5 S/cm. When the LLTO pellets were subject to cold isostatic pressing, the low-temperature (900 °C)-processed LLTO sample also presented a high conductivity of 2.1 × 10−5 S/cm. This work sheds light on the low-temperature synthesis of LLTO-based solid electrolytes for solid-state lithium battery applications.