Positive electrode material, preparation method and uses thereof

1. A positive electrode material comprising:

a substrate comprising secondary particles, wherein each secondary particle comprises a plurality of primary particles packed together, a molecular formula of the substrate is Li x Ni y CO z Mn k Al p O r A m , 0.95≤ x≤1.05, 0.70≤ y≤0.98, 0<z≤0.2, 0<k≤0.2, 0≤ p≤0.05, 1<r≤2, 0≤m≤2, m+r≤2, A is selected from F, Cl, Br, and any combinations thereof;

a coating layer disposed on a surface of the substrate, wherein the coating layer comprises an oxide of a coating element selected from Al, Ba, Zn, Ti, Zr, Mg, Y, Si, B, Co, P, and any combinations thereof,

wherein a powder resistivity ρ of the positive electrode material under a 12 MPa pressure is 500 Ω*cm-2,000 Ω*cm.

2. The positive electrode material of claim 1 , wherein the powder resistivity ρ of the positive electrode material under a 12 MPa pressure is 543 Ω*cm-1,653 Ω*cm.

3. The positive electrode material of claim 1 , wherein a content Mv of the coating element per unit volume of the positive electrode material is 400 μg/cm 3 to 15,000 μg/cm 3 .

4. The positive electrode material of claim 3 , wherein the content Mv of the coating element per unit volume of the positive electrode material is 800 μg/cm 3 to 10,000 μg/cm 3 .

5. The positive electrode material of claim 3 , wherein the powder resistivity ρ and the content Mv of the coating element satisfy: ρ/Mv≤1 Ω*cm 4 /μg.

6. The positive electrode material of claim 5 , wherein the powder resistivity ρ and the content Mv of the coating element satisfy: ρ/Mv≤0.5 Ω*cm 4 /μg.

7. The positive electrode material of claim 1 , wherein the coating element is selected from at least two of the group consisting of Al, Ba, Zn, Ti, Zr, Mg, Y, Si, B, Co, and P.

8. The positive electrode material of claim 1 , wherein the coating element is distributed on a surface of at least a part of the primary particles inside the secondary particles and distributed at grain boundaries between adjacent primary particles.

9. The positive electrode material of claim 1 , wherein a content of the coating element in the oxide coating layer is 60 wt % or more, based on a total content of the coating element in the positive electrode material.

10. The positive electrode material of claim 1 , wherein in the molecular formula of the substrate, 0.80≤y≤0.98, 0<z≤0.1, 0<k≤0.1, and 0≤p≤0.03.

11. The positive electrode material of claim 1 , wherein Dv50 of the secondary particles is 5 μm-18 μm, the primary particles have an average particle diameter of 0.1 μm-1 μm.

12. The positive electrode material of claim 1 , wherein a specific surface area of the positive electrode material is 0.1 m 2 /g-0.8 m 2 /g.

13. The positive electrode material of claim 1 , wherein a content of Li 2 CO 3 in residual lithium on a surface of the positive electrode material is less than 3,000 ppm, and a content of LiOH in the residual lithium on the surface of the positive electrode material is less than 5,000 ppm.

14. The positive electrode material of claim 13 , wherein in the residual lithium on the surface of the positive electrode material, the content of Li 2 CO 3 is less than the content of LiOH.

15. A method for preparing a positive electrode material, the method comprising:

forming a substrate, wherein the substrate comprises secondary particles, the secondary particle comprises a plurality of primary particles packed together, a molecular formula of the substrate is 0.70≤ y≤0.98, 0<z≤0.2, 0<k≤0.2, 0≤p≤0.05, 1≤r≤2, 0≤m≤2, m+r≤2, A is selected from F, Cl, Br, and any combinations thereof; and

forming a coating layer on a surface of the substrate, wherein the coating layer comprises an oxide of a coating element selected from Al, Ba, Zn, Ti, Zr, Mg, Y, Si, B, Co, P, and any combinations thereof,

wherein a powder resistivity ρ of the positive electrode material under a 12 MPa pressure is 500 Ω*cm-2,000 Ω*cm.

16. The method of claim 15 , wherein forming the substrate further comprises:

forming a mixture of a lithium source and a metal source, wherein the metal source comprises a metal element selected from the group consisting of Ni, Co, Mn, Al, and any combinations thereof; and

sintering the mixture.

17. The method of claim 16 , wherein the metal source is selected from the group consisting of Ni 0.5 Co 0.2 Mn 0.3 (OH) 2 , Ni 0.5 Co 0.25 Mn 0.25 (OH) 2 , Ni 0.55 Co 0.15 Mn 0.3 (OH) 2 , Ni 0.55 Co 0.1 Mn 0.35 (OH) 2 , Ni 0.55 Co 0.05 Mn 0.4 (OH) 2 , Ni 0.6 Co 0.2 Mn 0.2 (OH) 2 , Ni 0.75 Co 0.1 Mn 0.15 (OH) 2 , Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 , Ni 0.88 Co 0.05 Mn 0.07 (OH) 2 , 0.9Ni 0.8 Co 0.2 (OH) 2 ·0.1Al 2 (OH) 3 , 0.9Ni 0.9 Co 0.05 Mn 0.05 (OH) 2 ·0.1Al 2 (OH) 3 , and any combinations thereof,

wherein the lithium source is selected from the group consisting of LiOH·H 2 O, LiOH, Li 2 CO 3 , Li 2 O, and any combinations thereof.

18. The method of claim 16 , wherein the sintering is performed at a temperature of 800° C. with an oxygen concentration greater than or equal to 20%.

19. The method of claim 15 , wherein forming the coating layer further comprises:

mixing the substrate with a compound containing the coating element, wherein the compound is selected from the group consisting of Al 2 O 3 , ZnO, ZrO 2 , TiO 2 , MgO, WO 3 , Y 2 O 3 , Co 2 O 3 , Ba(NO 3 ) 2 , Co 2 O 3 , P 2 O 5 , H 3 BO 3 , and any combinations thereof; and

sintering the mixed substrate and compound.

20. The method of claim 15 , wherein the coating element has a dosage from 0.01 wt % to 0.5 wt %, based on a mass of the substrate, and sintering the mixed substrate and compound is performed at a temperature from 200° C.-700° C.