A New La2/3LixTi1-xAlxO3 Solid Solution: Structure, Microstructure, and Li+ Conductivity

The stoichiometry range, crystal chemistry, ionic conductivity, and electrochemical window of the La2/3LixTi1-xAlxO3 system with perovskite-related structure have been studied. The range of the 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 ≈ √2ap, b ≈ √2ap, c ≈ 2ap. The ionic conductivity of the materials and its dependence on composition and temperature have been examined by complex impedance spectroscopy. Lithium ion conductivity increases with increasing lithium content up to a value (7.6 × 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 1.6 V.