TiO<sub>2</sub> phase-controlled synthesis of Li-La-TiO solid electrolytes for advanced all-solid-state batteries

Abstract

This study focused on achieving high ionic conductivity in Li-La-TiO (LLTO) solid electrolyte. To enhance ionic conductivity, the synthesis reaction was optimized by controlling the composite crystal structure of TiO2 at the B-site of the perovskite (ABO(3)) structured LLTO, incorporating rutile, brookite, and anatase phases. The solid-phase LLTO, synthesized utilizing the core - shell structured composite-phase TiO2 developed in this study for the first time, successfully transformed its crystal structure to beta-LLTO (tetragonal to cubic). This resulted in a significant improvement in ionic conductivity (i.e. 1.11 x 10(-4) Scm(-1)). The study findings confirmed that the composite crystal structure TiO2 used in the solid-phase synthesis of LLTO induced an increase in oxygen vacancies during the synthesis process, thereby reducing the step-free energy required for the final synthesis.