Secondary battery, process for preparing the same and apparatus containing the secondary battery
This application relates to a secondary battery, a process for preparing the same and an apparatus containing the secondary battery. In particular, the negative electrode plate comprises a negative current collector and a negative electrode film, wherein the negative electrode film comprises a first negative electrode film and a second negative electrode film, the first negative electrode film is disposed on at least one surface of the negative current collector and comprises a first negative electrode active material, the first negative electrode active material comprises graphite, and the particle size uniformity of the first negative electrode active material is from 0.4 to 0.6; the second negative electrode film is disposed on the first negative electrode film and comprises a second negative electrode active material, the second negative electrode active material comprises artificial graphite, and the particle size uniformity of the second negative electrode active material is from 0.25 to 0.45.
1. A secondary battery, comprising a negative electrode plate, the negative electrode plate comprising a negative electrode current collector and a negative electrode film, and the negative electrode film comprising a first negative electrode film and a second negative electrode film,
wherein the first negative electrode film is disposed on at least one surface of the negative electrode current collector and comprises a first negative electrode active material, and the first negative electrode active material comprises graphite and has a particle size uniformity of from 0.45 to 0.6, in which the first negative electrode active material has a volume distribution particle size D V 50 of from 13.7 μm to 20.7 μm; and
the second negative electrode film is disposed on the first negative electrode film and comprises a second negative electrode active material, and the second negative electrode active material comprises artificial graphite and has a particle size uniformity of from 0.25 to 0.45, in which the second negative electrode active material has a volume distribution particle size D V 50 of from 10 μm to 18 μm.
2. The secondary battery according to claim 1 , wherein the second negative electrode active material has a particle size uniformity of from 0.3 to 0.4.
3. The secondary battery according to claim 1 , wherein a ratio of the particle size uniformity of the first negative electrode active material to the particle size uniformity of the second negative electrode active material is from 1.05 to 1.9.
4. The secondary battery according to claim 1 , wherein the second negative electrode active material comprises primary particles and secondary particles, and a number percentage of the secondary particles in the secondary negative electrode active material satisfies 30%≤B≤100%.
5. The secondary battery according to claim 1 , wherein a mass percentage of the artificial graphite in the second negative electrode active material is from 80% to 100%.
6. The secondary battery according to claim 1 , wherein the first negative electrode active material has a volume distribution particle size D V 10 less than the second negative electrode active material.
7. The secondary battery according to claim 1 , wherein the first negative electrode active material has a tap density greater than the second negative electrode active material.
8. The secondary battery according to claim 1 , wherein the first negative electrode active material comprises the following (1), (3) and (4) and optionally further comprises the following (5)-(6):
(1) the first negative electrode active material has a volume distribution particle size D V 10 of from 4.8 μm to 8.0 μm;
(3) the first negative electrode active material has a volume distribution particle size D V 99 of from 42 μm to 66 μm;
(4) the first negative electrode active material has a particle size distribution (D V 90−D V 10)/D V 50 of from 1.2 to 2.4;
(5) the first negative electrode active material has a tap density of from 0.88 g/cm 3 to 1.28 g/cm 3 ; and
(6) the first negative electrode active material has a powder compacted density of from 1.77 g/cm 3 to 1.97 g/cm 3 at a pressure of 30,000N.
9. The secondary battery according to claim 1 , wherein the second negative electrode active material comprises the following (1), (3) and (4) and optionally further comprises the following (5)-(6):
(1) the second negative electrode active material has a volume distribution particle size D V 10 of from 6.0 μm to 9.5 μm;
(3) the second negative electrode active material has a volume distribution particle size D V 99 of from 25 μm to 45 μm;
(4) the second negative electrode active material has a particle size distribution (D V 90−D V 10)/D V 50 of from 0.9 to 1.5;
(5) the second negative electrode active material has a tap density of from 0.7 g/cm 3 to 1.4 g/cm 3 ; and
(6) the second negative electrode active material has a powder compacted density of from 1.65 g/cm 3 to 1.85 g/cm 3 at a pressure of 30,000N.
10. The secondary battery according to claim 1 , wherein the first negative electrode active material comprises one or more selected from the group consisting of artificial graphite and natural graphite.
11. The secondary battery according to claim 1 , wherein the first negative electrode active material comprises artificial graphite and the artificial graphite constitutes from 50% to 100% by mass of the first negative electrode active material.
12. The secondary battery according to claim 1 , wherein the negative electrode film further satisfies one or more of the following (1)-(3):
(1) the negative electrode film has a areal density of from 90 g/m 2 to 136 g/m 2 ;
(2) the negative electrode film has a compacted density of from 1.5 g/cm 3 to 1.75 g/cm 3 ; and
(3) the negative electrode film has a thickness of from 60 μm to 80 μm.
13. An apparatus, comprising the secondary battery according to claim 1 .
14. The secondary battery according to claim 1 , wherein the first negative electrode active material has a particle size uniformity of from 0.5 to 0.57.
15. The secondary battery according to claim 1 , wherein the second negative electrode active material has a particle size uniformity of from 0.32 to 0.38.
16. The secondary battery according to claim 1 , wherein a ratio of the particle size uniformity of the first negative electrode active material to the particle size uniformity of the second negative electrode active material is from 1.2 to 1.6.
17. The secondary battery according to claim 1 , wherein the second negative electrode active material comprises secondary particles, and a number percentage of the secondary particles in the secondary negative electrode active material satisfies 50%≤B≤100%.
18. The secondary battery according to claim 1 , wherein a mass percentage of the artificial graphite in the second negative electrode active material satisfies from 90% to 100%.
19. A process for preparing a secondary battery, comprising preparing a negative electrode plate of the secondary battery by the following steps:
1) Forming a first negative electrode film comprising a first negative electrode active material on at least one surface of a negative electrode current collector, wherein the first negative electrode active material comprises graphite and has a particle size uniformity of from 0.45 to 0.6, in which the first negative electrode active material has a volume distribution particle size D V 50 of from 13.7 μm to 20.7 μm; and
2) forming a second negative electrode film comprising a second negative electrode active material on the first negative electrode film, wherein the second negative electrode active material comprises artificial graphite; and the second negative electrode active material has a particle size uniformity of from 0.25 to 0.45 in which the second negative electrode active material has a volume distribution particle size D V 50 of from 10 μm to 18 μm.