Positive electrode active material, positive electrode plate, lithium-ion secondary battery, and apparatus

1. A positive electrode active material, wherein,

the positive electrode active material comprises active material particles satisfying a chemical formula Li 1+x (Ni a Co b Mn c ) 1−d M d O 2−y A y , wherein M is one or more selected from Zr, Sr, B, Ti, Mg, Sn and Al, A is one or more selected from S, N, F, Cl, Br and I, −0.01≤x≤0.2, 0.5≤a≤0.7, 0<b≤0.2, 0.12≤b/c≤0.9, 0.002≤b×c/a 2 ≤0.23, a+b+c=1, 0≤d≤0.1, and 0≤y<0.2; and

an interval particle size distribution curve of the positive electrode active material based on volume particle size distribution has a full width at half maximum D FW of from 4 μm to 8 μm;

the positive electrode active material has a powder compaction density of from 3.15 g/cm 3 to 3.6 g/cm 3 under a pressure of 3 tons.

2. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a particle size distribution D n 10 and a particle size distribution D v 50 satisfying: D n 10≥0.2 μm, and 2 μm≤D v 50≤7 μm;

preferably, D n 10≥1 μm, and 3 μm≤D v 50≤6 μm.

3. The positive electrode active material according to claim 2 , wherein the positive electrode active material has a particle size distribution D n 10 and a particle size distribution D v 50 satisfying: D n 10≥1 μm, and 3 μm≤D v 50≤6 μm.

4. The positive electrode active material according to claim 1 , wherein the full width at half maximum D FW of of the interval particle size distribution curve of the positive electrode active material and a particle size distribution D v 99 and a particle size distribution D v 10 of the positive electrode active material satisfy: 0.4≤D FW /(D v 99−D v 10)≤1.2.

5. The positive electrode active material according to claim 2 , wherein the full width at half maximum D FW of the interval particle size distribution curve of the positive electrode active material and a particle size distribution D v 99 and a particle size distribution D v 10 of the positive electrode active material satisfy: 0.4≤D FW /(D v 99−D v 10)≤1.2.

6. The positive electrode active material according to claim 4 , wherein the full width at half maximum D FW of the interval particle size distribution curve of the positive electrode active material and a particle size distribution D v 99 and a particle size distrigbution D v 10 of the positive electrode active material satisfy: 0.5≤D FW /(D v 99−D v 10)≤1.0.

7. The positive electrode active material according to claim 4 , wherein the particle size distribution D v 99 and the particle size distribution D v 10 of the positive electrode active material satisfy: 7 μm≤D v 99≤1.5 μm, and 1 μm≤D v 10≤4 μm.

8. The positive electrode active material according to claim 7 , wherein the particle size distribution D v 99 and the particle size distribution D v 10 of the positive electrode active material satisfy: 8 μm≤D v 99≤13 μm, and 1.5 μm≤D v 10≤2.5 μm.

9. The positive electrode active material according to claim 1 , wherein the positive electrode active material comprises monodispersed primary particles, and the monodispersed primary particles have a number percentage of 50% or more in the positive electrode active material.

10. The positive electrode active material according to claim 9 , wherein the monodispersed primary particles have a number percentage of 70% or more in the positive electrode active material.

11. The positive electrode active material according to claim 9 , wherein the positive electrode active material further comprises secondary particles aggregated from a plurality of primary particles;

the secondary particles have a number percentage of from 5% to 50% in the positive electrode active material.

12. The positive electrode active material according to claim 11 , wherein the secondary particles have a number percentage of from 10% to 30% in the positive electrode active material.

13. The positive electrode active material according to claim 11 , wherein a ratio of particle sizes of the primary particles in the secondary particles to the secondary particles is from 0.03to 0.9.

14. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a tap density of from 1.6g/cm 3 to 2.6g/cm 3 .

15. The positive electrode active material according to claim 1 , wherein the positive electrode active material further comprises a coating comprising an X element oxide on outer surface of the active material particles, and the X element is one or more of a trivalent element and a tetravalent element.

16. The positive electrode active material according to claim 15 , wherein the X element is selected from one or more of Zr, B, Ti, Al and Sn.

17. The positive electrode active material according to claim 15 , wherein the coating in the positive electrode active material has a weight of from 0.01% to 1%, relative to a weight of the active material particles.

18. A positive eletrode plate, comprising a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer comprising the positive electrode active material according to claim 1 .

19. A lithium-ion secondary battery, comprising the positive electrode plate according to claim 18 .