The invention discloses a preparation method of a high-
nickel ternary
cathode material. The method comprises the steps of 1) pre-oxidizing a high-
nickel ternary
cathode material precursor with an
oxidizing agent to obtain an oxidized high-
nickel ternary precursor; 2) uniformly mixing the pre-oxidized high-nickel ternary precursor with a
lithium source and a modified assistant, and performing calcining to obtain an oxidized and modified high-nickel ternary
cathode material; 3) carrying out
coating modification of a
lithium-containing compound on the oxidized and modified high-nickel ternary
cathode material to obtain a coated and modified high-nickel ternary
cathode material for a
power battery. According to the method disclosed by the invention, the material precursor is pre-oxidized withthe
oxidizing agent, so that Ni<2+> can be fully oxidized into Ni<3+>, the cation mixing degree of the material is reduced, and the capacity of the material is expanded; and through the
coating modification of the
lithium-containing compound, the content of residual alkali on the surface of the material can be reduced, the generation of side reactions can be effectively inhibited, the embedding and separation of lithium ions are improved, and finally the
cycling performance and the rate performance of the material are improved.