Artificial graphite, secondary battery, method for the preparation thereof, and apparatus
View Patent ↗The present application discloses an artificial graphite, a secondary battery, a preparation method and an apparatus. The artificial graphite includes secondary particles formed by agglomeration of primary particles, the artificial graphite having a volume average particle size Dv50, denoted as A, the artificial graphite through powder compaction under a pressure of 2000 kg having a volume average particle size Dv50, denoted as B, wherein A and B satisfies: B/A≥0.85. Using the artificial graphite provided by the present application can greatly reduce the cyclic expansion of the secondary battery.
1. An artificial graphite comprising secondary particles formed by agglomeration of primary particles, the artificial graphite having a volume average particle size Dv50 denoted as A, and the artificial graphite through powder compaction under a pressure of 19600N/1.327 cm 2 having a volume average particle size Dv50 denoted as B, wherein A and B satisfy: 0.85≤B/A≤0.92,
the artificial graphite has a volume average particle size Dv50 of from 15 μm to 18 μm.
2. The artificial graphite according to claim 1 , wherein A and B satisfy: 0.88≤B/A≤0.92.
3. The artificial graphite according to claim 1 , wherein when the artificial graphite is present in an electrode plate with a compaction density of from 1.6 g/cm 3 to 1.7 g/cm 3 , a ratio of a peak area of 004 crystal plane to a peak area of 110 crystal plane of the artificial graphite is from 8 to 12.
4. The artificial graphite according to claim 1 , wherein the secondary particles have one or more of a block shape, a spherical shape, and a spheroid shape.
5. The artificial graphite according to claim 1 , wherein the artificial graphite has a number particle size distribution Dn10 satisfying 1.2 μm≤Dn10≤3 μm.
6. The artificial graphite according to claim 1 , wherein the artificial graphite has a graphitization degree of from 90% to 95%.
7. The artificial graphite according to claim 1 , wherein a peak D intensity ID and a peak G intensity IG of the artificial graphite satisfy: 0.1≤I D /I G ≤0.2.
8. The artificial graphite according to claim 1 , wherein the artificial graphite further satisfies one or more of the following (1)-(3):
(1) the artificial graphite has a volume particle size distribution Dv10 of Dv10≤6 μm;
(2) the artificial graphite ha a particle size distribution (Dv90-Dv10)/Dv50 of from 1.1 to 1.8;
(3) the artificial graphite ha a specific surface area SSA of from 0.5 m 2 /g to 2.0 m 2 /g.
9. The artificial graphite according to claim 8 , wherein the artificial graphite further satisfies one or more of the following (1)-(3):
(1) the artificial graphite has a volume particle size distribution Dv10 of 6.5 μm≤Dv10 ≤10.5 μm;
(2) the artificial graphite has a particle size distribution (Dv90-Dv10)/Dv50 of from 1.2 to 1.5;
(3) the artificial graphite has a specific surface area SSA of from 0.8 m 2 /g to 1.5 m 2 /g.
10. The artificial graphite according to claim 1 , wherein
the artificial graphite has a tap density of from 0.85 g/cm 3 to 1.35 g/cm 3 ; and/or,
the artificial graphite has a powder compaction density under a pressure of 2000 kgf of from 1.65 g/cm 3 to 1.85 g/cm 3 .
11. The artificial graphite according to claim 10 , wherein
the artificial graphite has a tap density of from 0.95 g/cm 3 to 1.15 g/cm 3 ; and/or,
the artificial graphite has a powder compaction density under a pressure of 2000 kgf of from 1.68 g/cm 3 to 1.83 g/cm 3 .
12. The artificial graphite according to claim 1 , wherein the secondary particles has a number proportion in the artificial graphite of ≥60%.
13. The artificial graphite according to claim 1 , wherein the artificial graphite has a gram capacity of from 350 mAh/g to 359 mAh/g.
14. The artificial graphite according to claim 1 , wherein the artificial graphite has an amorphous carbon coating layer on at least a part of the surface thereof.
15. A secondary battery comprising a negative electrode plate, the negative electrode plate comprises a negative active material, and the negative active material comprises the artificial graphite according to claim 1 .
16. A method for preparing an artificial graphite, including the following steps:
(1) crushing green coke materials and classifying them to remove fine powder so as to obtain a precursor;
(2) shaping the precursor crushed in step (1);
(3) granulating the precursor treated in step (2) during which a binder is added in an amount not exceed 5% of the total weight of the green coke materials;
(4) subjecting the product obtained in step (3) to a graphitization treatment at a temperature of from 2800° C. to 3200° ° C. to obtain the artificial graphite;
wherein the artificial graphite comprises secondary particles formed by agglomeration of primary particles, the artificial graphite has a volume average particle size Dv50, denoted as A, the artificial graphite through powder compaction under a pressure of 19600N/1.327 cm 2 has a volume average particle size Dv50, denoted as B, and A and B satisfy: 0.85≤B/A≤0.92,
the artificial graphite has a volume average particle size Dv50 of from 15 μm to 18 μm.
17. The preparation method according to claim 16 , wherein the green coke material comprises one or more of green petroleum coke, green pitch coke and metallurgical coke.
18. The preparation method according to claim 16 , wherein the green coke material is non-needle coke; and/or,
the green coke material has a volatile content of from 6% to 12%; and/or,
the green coke material has a sulfur content of ≤2%.
19. The preparation method according to claim 16 , wherein the step (2) further comprises removing fine powder after shaping; the precursor treated in step (2) through a fine powder removal treatment has a number particle size D n 10 that is controlled to be ≥0.5 μm.
20. The preparation method according to claim 16 , further comprising a step (5) of mixing the artificial graphite obtained in step (4) with an organic carbon source to obtain a mixture and heat treating the mixture at a temperature of from 850° C. to 1250° C.