Electrochemical properties of LiNi1−yTiyO2 synthesized by ball milling and solid-state reaction method

LiNi1−yTiyO2 (y = 0.000, 0.012, 0.025, 0.050, 0.100 and 0.150) were synthesized by ball milling and the solid-state reaction method. The optimum conditions to synthesize a cathode material LiNi0.975Ti0.025O2 are milling for 28 h and then preheating at 600 °C for 16 h and finally calcining at 750 °C for 30 h in an O2 stream. LiNi1−yTiyO2 (0 ≤ y ≤ 0.150) synthesized under these optimum conditions have the α-NaFeO2 structure of the rhombohedral system (space group; R3¯m). The samples with y = 0, 0.012 and 0.025 show splitting of 0 0 6 and 1 0 2 peaks of 1 0 8 and 1 1 0 peaks, indicating the decrease in cation mixing. The voltage versus discharge capacity curves for y = 0.012 and 0.025 exhibit three distinct plateaus corresponding to phase transitions. Among LiNi1−yTiyO2 (0 ≤ y ≤ 0.150), LiNi0.975Ti0.025O2 has the largest first discharge capacity, 155 mAh/g and the relatively good cycling performance (77% at n = 10).