Secondary battery and apparatus contained the secondary battery

1. A secondary battery, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector and comprising a positive active material; the negative electrode plate comprising a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material,

wherein the positive active material comprises one or more of layered lithium transition metal oxides and modified compounds thereof, and

the negative electrode active material comprises artificial graphite and natural graphite, and the negative electrode plate satisfies 0.02≤I 3R(012) /I 2H(100) ≤0.18,

in which the I 3R(012) is a peak intensity of an X-ray diffraction peak of a 3R-phase 012 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(100) is a peak intensity of an X-ray diffraction peak of a 2H-phase 100 crystal plane of the negative electrode active material in the negative electrode plate.

2. The secondary battery according to claim 1 , wherein the negative electrode plate further satisfies: 0.02≤I 3R(101) /I 2H(101) ≤0.18,

in which the I 3R(101) is a peak intensity of an X-ray diffraction peak of a 3R-phase 101 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(101) is a peak intensity of an X-ray diffraction peak of a 2H-phase 101 crystal plane of the negative electrode active material in the negative electrode plate.

3. The secondary battery according to claim 1 , wherein the natural graphite constitutes <50% by mass of the negative electrode active material.

4. The secondary battery according to claim 1 , wherein the negative electrode active material has an average particle size D v 50 of from 11 μm to 15 μm.

5. The secondary battery according to claim 1 , wherein the negative electrode active material has a tap density of ≥1.1 g/cm 3 ; and/or,

the negative electrode active material has a graphitization degree of from 92% to 96%.

6. The secondary battery according to claim 1 , wherein the negative electrode film has an areal density of from 10 mg/cm 2 to 13 mg/cm 2 ; and/or,

the negative electrode film has a compacted density of from 1.6 g/cm 3 to 1.8 g/cm 3 .

7. The secondary battery according to claim 1 , wherein the layered lithium transition metal oxides comprise one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminium oxide and modified compounds thereof.

8. A secondary battery, comprising a positive electrode plate and a negative electrode plate, the positive electrode plate comprising a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector and comprising a positive active material; the negative electrode plate comprising a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material;

wherein the positive active material comprises one or more of lithium-containing phosphates with olivine structure and modified compounds thereof, and

the negative electrode active material comprises artificial graphite and natural graphite, and the negative electrode plate satisfies 0.04≤I 3R(012) /I 2H(100) ≤0.22

in which the I 3R(012) is a peak intensity of an X-ray diffraction peak of a 3R-phase 012 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(100) is a peak intensity of an X-ray diffraction peak of a 2H-phase 100 crystal plane of the negative electrode active material in the negative electrode plate.

9. The secondary battery according to claim 8 , wherein the negative electrode plate further satisfies: 0.04≤I 3R(101) /I 2H(101) ≤0.22;

in which the I 3R(101) is a peak intensity of an X-ray diffraction peak of a 3R-phase 101 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(101) is a peak intensity of an X-ray diffraction peak of a 2H-phase 101 crystal plane of the negative electrode active material in the negative electrode plate.

10. The secondary battery according to claim 8 , wherein the natural graphite constitutes >20% by mass of the negative electrode active material by mass.

11. The secondary battery according to claim 8 , wherein the negative electrode active material has an average particle size D v 50 of from 15 μm to 19 μm.

12. The secondary battery according to claim 8 , wherein the negative electrode active material has a tap density of <1.1 g/cm 3 ; and/or,

the negative electrode active material has a graphitization degree of from 92% to 95%.

13. The secondary battery according to claim 8 , wherein the negative electrode film has an areal density of from 7 mg/cm 2 to 10 mg/cm 2 ; and/or,

the negative electrode film has a compacted density of from 1.5 g/cm 3 to 1.7 g/cm 3 .

14. The secondary battery according to claim 8 , wherein the lithium-containing phosphates with olivine structure comprises one or more of lithium iron phosphate, composite materials of the lithium iron phosphate and a carbon, and modified compounds thereof.

15. The secondary battery according to claim 1 , wherein the negative electrode plate satisfies 0.04≤I 3R(012) /I 2H(100) ≤0.12

in which the I 3R(012) is a peak intensity of an X-ray diffraction peak of a 3R-phase 012 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(100) is a peak intensity of an X-ray diffraction peak of a 2H-phase 100 crystal plane of the negative electrode active material in the negative electrode plate.

16. The secondary battery according to claim 1 , wherein the negative electrode plate further satisfies: 0.04≤I 3R(101) /I 2H(101) ≤0.12,

in which the I 3R(101) is a peak intensity of an X-ray diffraction peak of a 3R-phase 101 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(101) is a peak intensity of an X-ray diffraction peak of a 2H-phase 101 crystal plane of the negative electrode active material in the negative electrode plate.

17. The secondary battery according to claim 1 , wherein the natural graphite constitutes from 15% to 25% by mass of the negative electrode active material.

18. The secondary battery according to claim 1 , wherein the negative electrode active material has an average particle size D v 50 of from 12 μm to 14 μm.

19. The secondary battery according to claim 8 , wherein the negative electrode plate further satisfies 0.06≤I 3R(102) /I 2H(100) ≤0.18;

in which the I 3R(012) is a peak intensity of an X-ray diffraction peak of a 3R-phase 012 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(100) is a peak intensity of an X-ray diffraction peak of a 2H-phase 100 crystal plane of the negative electrode active material in the negative electrode plate.

20. The secondary battery according to claim 8 , wherein the negative electrode plate further satisfies: 0.06≤I 3R(101) /I 2H(101) ≤0.18;

in which the I 3R(101) is a peak intensity of an X-ray diffraction peak of a 3R-phase 101 crystal plane of the negative electrode active material in the negative electrode plate, and the I 2H(101) is a peak intensity of an X-ray diffraction peak of a 2H-phase 101 crystal plane of the negative electrode active material in the negative electrode plate.