Modified positive electrode material and preparation method therefor, and lithium ion battery

1. A modified positive electrode material, comprising:

a core, the core being a positive electrode material containing a manganese element and a nickel element; and

a coating layer, the coating layer comprising a first oxide coating layer, the first oxide coating layer coating on a surface of the core by a mechanical fusion treatment, and a first element forming the first oxide coating layer comprising, one or more of a group consisting of Si, Ti, V, Zr, Mo, W, Bi, Nb, and Ru;

the modified positive electrode material further comprising: a second oxide coating layer, the second oxide coating layer coating on a surface of the core, and being arranged between the positive electrode material and the first oxide coating layer, and a second element forming the second oxide coating layer being selected from elements of Group IVB and/or Group VB;

the modified positive electrode material is denoted by the following general formula: Li 1+i Ni x Co y Mn (1-x-y) M m O 2 ·[MO 2 ] n , −0.05≤i≤0.2, 0.5≤x≤0.8, 0.05≤y≤0.3, 0≤m≤0.03, and 0≤n≤0.05, wherein M of Li 1+i Ni x Co y Mn (1-x-y) M m O 2 represents the second element, and M of [MO 2 ] n represents the first element.

2. The modified positive electrode material according to claim 1 , wherein the first element forming the first oxide coating layer is selected from one or more of a group consisting of Mo, W, and Bi.

3. The modified positive electrode material according to claim 1 , wherein a total mole number of the core is m, and a mole number of the first oxide coating layer is greater than 0% m and smaller than or equal to 5% m.

4. The modified positive electrode material according to claim 1 , wherein the second element forming the second oxide coating layer is selected from one or more of a group consisting of Ti, V, and Zr.

5. The modified positive electrode material according to claim 1 , wherein a total mole number of the core is m, and a mole number of the second oxide coating layer is 0.01% m to 3.00% m.

6. The modified positive electrode material according to claim 1 , wherein the core is a concentration gradient spherical particle; and from inside to outside in a radial direction, a mole percentage of the nickel element in all metal elements is gradually decreased, and a mole percentage of the manganese element in all the metal elements is gradually increased.

7. The modified positive electrode material according to claim 6 , wherein a radius of the core is R; in a surface layer of the core, a mole percentage of the nickel element is 0% to 60% of a total mole number of all metal elements in the surface layer, and a mole percentage of the manganese element is 10% to 100% of the total mole number of all the metal elements in the surface layer; in an interior of the core, a mole percentage of the nickel element is 60% to 100% of a total mole number of all metal elements in the interior, and a mole percentage of the manganese element is 0% to 10% of the total mole number of all the metal elements in the interior; and the interior refers to a portion from a spherical center to R/2 in the radial direction of the spherical particle, and the surface layer refers to a portion from R/2 to R in the radial direction of the spherical particle.

8. A preparation method for the modified positive electrode material according to claim 1 , comprising: providing a precursor particle containing the nickel element and the manganese element, mixing the precursor particle containing the nickel element and the manganese element with a lithium source, and performing a sintering treatment; water-washing a product obtained after the sintering treatment, and adding a salt formed by a second element in the water-washing: performing a second heat treatment after the water-washing, to obtain a particle coated with a second oxide coating layer; and

performing the mechanical fusion treatment on the particle coated with the second oxide coating layer and the first oxide, to obtain the modified positive electrode material, wherein the first element of the first oxide is selected from one or more of a group consisting of Si, Ti, V, Zr, Mo, W, Bi, Nb, and Ru, and the salt formed by the second element and a second element of the second oxide are each selected from elements of Group IVB and/or Group VB.

9. The preparation method for the modified positive electrode material according to claim 8 , wherein the preparation method for the modified positive electrode material further comprising: performing a first heat treatment after the mechanical fusion treatment, to obtain the modified positive electrode material, while a temperature is 100 to 300° C. and a time of the first heat treatment is 3 to 5 h.

10. The preparation method for the modified positive electrode material according to claim 8 , wherein a temperature of the second heat treatment is 200 to 900° C., or 300 to 700° C., and a time of the second heat treatment is 1 to 20 h, or 3 to 12 h.

11. The preparation method for the modified positive electrode material according to claim 8 , wherein a metal element of a second metal salt is selected from one or more of a group consisting of Ti, V, and Zr.

12. The preparation method for the modified positive electrode material according to claim 8 , wherein the modified positive electrode material is obtained through a first heat treatment after the mechanical fusion treatment, while a temperature of the first heat treatment is 100 to 300° C., and a time of the first heat treatment is 3 to 5 h.

13. A lithium ion battery, comprising a positive electrode, wherein the positive electrode comprises the modified positive electrode material according to claim 1 .