Preparation method of lithium-rich cathode material for lithium ion battery

The invention discloses a preparation method of a lithium-rich cathode material for a lithium ion battery. The lithium-rich cathode material has a chemical formula of Li1.2Mn[0.6-x]Ni0.2RE[x]O2, and in the formula, x is 0-0.05 and RE is a rare earth element-lanthanum or cerium. The preparation method comprises the following steps: preparing a mixed solution from water-soluble manganese, nickel and lanthanum (or cerium) salts and a homogeneous precipitation agent-urea, and synthesizing a carbonate mixture by a hydrothermal process; performing ball milling and uniform mixing on the synthesized carbonate mixture and lithium carbonate, and performing high-temperature curing reaction of a mixture to obtain the lithium-rich cathode material. The preparation process is simple, the product cost is low, and the material quality is easy to control in the process; the lithium-rich cathode material prepared by the method has the characteristics of high specific capacity, good circulating stability, improved rate performance and the like.