Positive electrode active material, positive electrode plate, lithium-ion secondary battery, and apparatus
View Patent ↗The present application discloses a positive electrode active material, a positive electrode plate, a lithium-ion secondary battery, and an apparatus. The positive electrode active material satisfies 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, 0.12≤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 has a full width at half maximum D FW of from 4 μm to 8 μm. The positive electrode active material provided in the present application has relatively low cobalt content and relatively high cycle life and capacity performance.
1. A positive electrode active material, 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, a≤0.5, 0<b<0.15, 0.12<b/c<0.75, 0.002≤b×c/a 2 <(1.2×3.3÷5.5 2 ), 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 has a full width at half maximum D FW of from 4 μm to 8 μm; and the positive electrode active material further comprises secondary particles aggregated from a plurality of primary particles, and the secondary particles have a number percentage of from 5% to 50% in the positive electrode active material.
2. The positive electrode active material according to claim 1 , wherein 0.5≤ a≤0.7, 0.05≤b≤0.12, 0.12<b/c<0.75, and (0.5×2.5≥7 2 )≤b×c/a 2 ≤(3.5÷5.5 2 ).
3. The positive electrode active material according to claim 1 , wherein the positive electrode active material comprises one or more of LiNi 0.55 Co 0.05 Mn 0.4 O 2 , LiNi 0.55 Co 0.1 Mn 0.35 O 2 , LiNi 0.55 Co 0.09 Mn 0.36 O 2 , LiNi 0.65 Co 0.05 Mn 0.3 O 2 , LiNi 0.65 Co 0.09 Mn 0.26 O 2 , LiNi 0.65 Co 0.12 Mn 0.23 O 2 , LiNi 0.7 Co 0.05 Mn 0.25 O 2 and a positive electrode active material obtained after doping the above materials with the M element at transition metal site and/or doping the above materials with the A element at oxygen site.
4. 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.
5. The positive electrode active material according to claim 1 , 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 1 , 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≤15 μm, and 1 μm≤D v 10≤4 μm.
7. 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.
8. The positive electrode active material according to claim 1 , wherein the secondary particles have a number percentage of from 10% to 30% in the positive electrode active material.
9. The positive electrode active material according to claim 1 , wherein a ratio of particle sizes of the primary particles in the secondary particles to the secondary particles is from 0.03 to 0.9.
10. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a tap density of from 1.6 g/cm 3 to 2.6 g/cm 3 ; and/or,
the positive electrode active material has a powder compaction density of from 3.0 g/cm 3 to 3.6 g/cm 3 under a pressure of 3 tons.
11. The positive electrode active material according to claim 1 , wherein a surface of the positive electrode active material has a coating comprising an X element oxide, the X element is one or more of a trivalent element and a tetravalent element.
12. The positive electrode active material according to claim 11 , wherein the X element preferably comprises one or more of Zr, B, Ti, Al and Sn.
13. The positive electrode active material according to claim 11 , wherein the coating has a weight of from 0.01% to 1%, relative to a weight of the positive electrode active material before coating.
14. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a specific surface area of from 0.1 m 2 /g to 1.2 m 2 /g.
15. A positive electrode 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 .
16. A lithium-ion secondary battery, comprising the positive electrode plate according to claim 15 .
17. An electric vehicle, comprising the lithium-ion secondary battery according to claim 16 .
18. A method for preparing a positive electrode active material, comprising:
mixing a positive electrode active material precursor, a lithium source, and an optional M source and/or A source and sintering to obtain a sintered product;
crushing and sieving the sintered product to obtain an active material precursor;
optionally, coating the active material precursor with an X element oxide, the X element is one or more of a trivalent element and a tetravalent element;
tempering and sieving the active material precursor to obtain the positive electrode active material;
wherein the positive electrode active material satisfies 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,a≥0.5,0<b<0.15, 0.12<b/c<0.75, 0.002≤b×c/a 2 <(1.2×3.3÷5.5 2 ), 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 has a full width at half maximum D FW of from 4 μm to 8 μm; and the positive electrode active material further comprises secondary particles aggregated from a plurality of primary particles, and the secondary particles have a number percentage of from 5% to 50% in the positive electrode active material.
19. The method according to claim 18 , wherein the sintering temperature is from 820° C. to 1000° C.; and/or,
the tempering temperature is from 400° C. to 800° C.