Among various cathode materials for lithium-ion batteries, xLi 2 MnO 3 ⋅(1-x)LiMO 2 (M=Ni, Co, Mn) with layered structure has great potential due to its high specific capacity. In this work, LaPO 4 -coated Li 1.2 Mn 0.54 Co 0.13 Ni 0.13 O 2 cathode material was successfully synthesized by wet chemical deposition method, and La doping was achieved by calcination. The results of SEM, TEM, and HRTEM showed that LaPO 4 is successfully coated on the surface of the material, La is successfully doped into the material, and the interlayer spacing of the material becomes larger after modification. The results of XRD and XPS also showed that La was successfully doped into the material. The electrochemical characterization results showed that LaPO 4 modification significantly improved the electrochemical performance of the material. Most importantly, the lithium-ion diffusion coefficient of 2 wt%-LaPO 4 is as high as 4.07 × 10 −14 cm 2 ·s −1 , which is four times that of the pristine material. Its specific capacity at 10 C is 100.3 mAh·g −1 , which is about 90% higher than that of the unmodified material 52.8 mAh·g −1 . The LaPO 4 -modified lithium-rich manganese-based cathode material has such good rate performance, which is attributed to the triple effect of LaPO 4 modification on promoting lithium-ion diffusion, which promotes the diffusion of lithium ion in three stages, from bulk phase to interface and then to electrolyte. The schematic can be seen in the graphical abstract. Graphical abstract LaPO 4 coating and La 3+ doping schematic diagram