A new co-precipitation route was proposed to synthesize LiNi 0.8Al 0.2− x Ti x O 2 ( x=0.0-0.20) cathode materials for lithium ion batteries, with Ni(NO 3) 2, Al(NO 3) 3, LiOH·H 2O, and TiO 2 as the starting materials. Ultrasonic vibration was used during preparing the precursors, and the precursors were protected by absolute ethanol before calcination in the air. The influences of doped-Ti content, calcination temperature and time, additional Li content, and ultrasonic vibration on the structure and properties of LiNi 0.8Al 0.2− x Ti x O 2 were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge tests, respectively. The results show that the optimal molar fraction of Ti, calcination temperature and time, and additional molar fraction of Li for LiNi 0.8Al 0.2− x Ti x O 2 cathode materials are 0.1, 700°C, 20 h, and 0.05, respectively. Ti doping facilitates the formation of the α-NaFeO 2 layered structure, and ultrasonic vibration improves the electrochemical performance of LiNi 0.8Al 0.2− x Ti x O 2.