_: _{The effect of different ultrasonic time on the morphology, structure and electrochemical}_{performance of}_{Li-rich materials}_Li[Li_0.144_Ni_0.136_Co_0.136_Mn_0.544_]O₂_was_{studied by ultrasonic assisted co-precipitation method.}_Our_{study found that}_ultrasonic_{can make the materials more uniform, and therefore the structure became more reasonable, which is beneficial to improve the electrochemical performance. The}_sample_{with 8h ultrasonic}_time_{shows the best capacity, and the initial discharge specific capacity of 0.1C rate is 327.8 mAh g}_-1_{(higher than 265.2 mAh g}_-1_{of the sample without}_ultrasonic_{). The discharge capacity is 181.6 mAh g}_-1_{at 1C rate after 50 cycles, with the capacity retention of 84.8%. After the cyclic voltammetry test and the EIS test, it was found that the composite oxide had higher current and reduced charge transfer impedance, and better rate performance.}