Amorphous and perovskite Li_3xLa_(2/3)−xTiO₃ (thin) films via chemical solution deposition: solid electrolytes for all-solid-state Li-ion batteries

Thin films of amorphous and crystalline perovskite Li_3xLa_(2/3)−xTiO₃ (LLT) (x = 0.117) are prepared by means of aqueous chemical solution deposition onto rutile TiO₂ thin films as an anode, yielding an electrochemical half-cell. The Li-ion conductivity of the pin-hole free, amorphous LLT thin film (90 nm thick) is 3.8 × 10⁻⁸ S cm⁻¹ on Pt and 1.3 × 10⁻⁸ S cm⁻¹ on rutile TiO₂, while measuring perpendicular to the thin film direction with impedance spectroscopy. Grazing angle attenuated total reflectance-Fourier transform infrared spectroscopy shows that all organic precursor molecules have been decomposed at 500 °C. In addition, in situ (heating) X-ray diffraction analysis shows that phase pure crystalline perovskite LLT (x = 0.117) is formed on top of the rutile TiO₂ anode at 700 °C. Furthermore, thickness control is possible by varying the precursor solution concentration and the number of deposition cycles. The current study presents a promising synthesis route to develop all-solid-state battery devices based on multi-metal oxide materials using aqueous precursor chemistry.