New La2/3-xSrxLixTiO3 Solid Solution: Structure, Microstructure, and Li+ Conductivity

Abstract

The stoichiometry range, crystal chemistry, ionic conductivity, and electrochemical window of the La2/3-xSrxLixTiO3 system with a perovskite-related structure have been studied. The range of existence of the solid solution is (0.06 ≤ x ≤ 0.3). Powder X-ray diffraction and transmission electron microscopy results show that these oxides have a unit cell multiple of the perovskite cell with dimensions a ≈ √2 ap, b ≈ √2 ap, and c ≈ 2ap. The ionic conductivity of the material and its dependence on composition and temperature have been examined by complex impedance spectroscopy. Lithium ion conductivity increases with increasing lithium content up to the value 7.12 10-5 S·cm-1 at room temperature, corresponding to x = 0.25. Electrochemical experiments indicate that these materials can be used as solid electrolytes in secondary batteries having Li metal as the anode down to 1.75 V.