Characteristics of Li₂TiO₃-LiCrO₂ composite cathode powders prepared by ultrasonic spray pyrolysis

Li₂TiO₃-LiCrO₂ cathode powders of various compositions are prepared by spray pyrolysis. Pure Li₂TiO₃ powder and Li₂TiO₃-LiCrO2 composite cathode powder have a spherical shape, nonaggregated structure, and fine sizes even after post-treatment at 700 °C under nitrogen atmosphere. The optimum posttreatment temperature to obtain composite powders with high initial discharge capacity, high coulombic efficiency, and good cycle properties is 700 °C. The initial charge capacities increase when the LiCrO2 content of the composite increase. However, the 0.55Li₂TiO₃-0. 45LiCrO₂ composite cathode powders have the highest initial discharge capacity of 203 mAh g^-1, in which the capacity retention after 30 cycles is 96%. The dQ/dV curve of the first charge curve has a distinct oxidation peak at approximately 3.9 V, which corresponds to Cr oxidation. The oxidation peak shifts to a lower voltage range at approximately 3.6 V after the first cycling because an irreversible reaction takes place in the initial charge process. The composite cathode powders with low LiCrO₂ content have low initial charge/discharge capacities and good cycle properties because of the stabilizing effect of high amounts of an inactive Li₂TiO₃ component.