Positive electrode active material, positive electrode plate, electrochemical energy storage apparatus, and apparatus
This application provides a positive active material, a positive electrode plate, an electrochemical energy storage apparatus, and an apparatus. The positive active material is Li x Ni y Co z M k Me p O r A m , or Li x Ni y Co z M k Me p O r A m with a coating layer on its surface; and the positive active material is single crystal or quasi-single crystal particles, and a particle size D n 10 of the positive active material satisfies: 0.3 μm≤D n 10≤2 μm. In this application, particle morphology of the positive active material and an amount of micro powder in the positive active material are properly controlled, to effectively reduce side reactions between the positive active material and an electrolyte solution, decrease gas production of the electrochemical energy storage apparatus, and improve storage performance of the electrochemical energy storage apparatus without deteriorating an energy density, cycle performance, and rate performance of the electrochemical energy storage apparatus.
1. A positive active material, wherein
the positive active material is Li x Ni y Co z M k Me p O r A m , or Li x Ni y Co z M k Me p O r A m with a coating layer on its surface, wherein 0.85≤x≤1.15, 0<y<1, 0<z<1, 0<k<1, 0≤p≤0.1, 1≤r≤2, 0≤m≤1, m+r≤2, M is selected from one or two of Mn and Al, Me is selected from one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb, and A is selected from one or more of N, F, S, and Cl; and
the positive active material is single crystal or quasi-single crystal particles, and a particle size D n 10 of the positive active material satisfies: 0.3 μm≤D n 10≤2 μm, wherein
D n 10 is a corresponding particle size when a cumulative number distribution percentage of the positive active material reaches 10%, wherein
the particle size D n 10 of the positive active material measured in μm and a particle size D v 10 of the positive active material measured in μm satisfy: 0.15≤D n 10×D v 10≤6, and
D v 10 is a corresponding particle size when a cumulative volume distribution percentage of the positive active material reaches 10% the particle size D v 10 of the positive active material is 0.5 μm to 3 μm.
2. The positive active material according to claim 1 , wherein a coating element in the coating layer is selected from one or more of Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P.
3. The positive active material according to claim 1 , wherein
a theoretical specific surface area BET 1 of the positive active material and an actual specific surface area BET 2 of the positive active material satisfy: 0.3≤(BET 2 −BET 1 )/BET 1 ≤5.5, wherein
BET 1 =6/(ρ× D v 50);
ρ is an actual density of the positive active material, and a unit of measurement is g/cm 3 ; and
D v 50 is a corresponding particle size when the cumulative volume distribution percentage of the positive active material reaches 50%, and a unit of measurement is μm.
4. The positive active material according to claim 1 , wherein the actual specific surface area BET 2 of the positive active material is 0.5 m 2 /g to 1.5 m 2 /g.
5. The positive active material according to claim 1 , wherein the particle size D v 50 of the positive active material is 1 μm to 6 μm.
6. The positive active material according to claim 1 , wherein a differential particle size distribution curve of the positive active material has one and only one peak.
7. The positive active material according to claim 1 , wherein the particle size D n 10 of the positive active material satisfies: 0.5 μm≤D n 10≤1.5 μm.
8. The positive active material according to claim 1 , wherein the particle size D v 10 of the positive active material is 1 μm to 2 μm.
9. The positive active material according to claim 1 , wherein the particle size D v 50 of the positive active material is 2 μm to 5 μm.
10. A positive electrode plate, comprising the positive active material according to claim 1 .
11. An electrochemical energy storage apparatus, comprising the positive active material according to claim 1 .
12. An apparatus, wherein the apparatus is a vehicle and comprises the electrochemical energy storage apparatus according to claim 11 .