Mechanical and electrochemical properties of cubic and tetragonal LixLa0.557TiO3 perovskite oxide electrolytes

Solid oxide electrolytes with high Li ion conductivity and mechanical stability are vital for all solid-state lithium ion batteries. The perovskite material LixLa0.557TiO3 with various initial Li (0.303 ≤ x ≤ 0.370) is synthesized by traditional solid-state reaction. The cubic and tetragonal structures are prepared with fast and slow cooling, respectively. The results reveal that the Li ion conductivity of the cubic structure is higher. In fact, the bulk conductivity of 1.65 × 10−3 S cm−1 is obtained at room temperature for x = 0.350. The crystal structure is not affected by the Li2O quantity. In addition, Young's modulus, hardness, and fracture toughness are determined with indentation method for both structures. The Young's modulus increases with increasing Li2O. However, hardness and fracture toughness keep a relatively stable value independent of Li2O quantity.