Secondary batteries and power consumption devices

Abstract

The present application provides a secondary battery and a power consumption device. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer has a first surface away from the negative electrode current collector and a second surface provided opposite to the first surface. Let the thickness of the negative electrode film layer be H. The region within the thickness range from 0.3H from the second surface of the negative electrode film layer is defined as the first region of the negative electrode film layer, and the region within the thickness range from 0.3H from the first surface of the negative electrode film layer is defined as the second region of the negative electrode film layer. The first region contains a first active material, the first active material contains a first carbon-based material, the first carbon-based material has a pore structure, the second region contains a second active material, the second active material contains a second carbon-based material, and at least a part of the surface of the second carbon-based material has a carbon coating layer. On the premise that the secondary battery has a high energy density, the present application can achieve both good kinetic performance and storage performance.

Claims

1. A secondary battery including a negative electrode sheet, The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer formed on at least one surface of the negative electrode current collector. The negative electrode film layer has a first surface away from the negative electrode current collector and a second surface provided opposite to the first surface. Let H be the thickness of the negative electrode film layer, and the region within the thickness range from the second surface of the negative electrode film layer to 0.3H be defined as the first region of the negative electrode film layer, and the region within the thickness range from the first surface of the negative electrode film layer to 0.3H be defined as the second region of the negative electrode film layer. The first region comprises a first active material, the first active material comprises a first carbon-based material, and the first carbon-based material has a pore structure. A secondary battery wherein the second region comprises a second active material, the second active material comprises a second carbon-based material, and at least a portion of the surface of the second carbon-based material has a carbon coating layer.

2. The secondary battery according to claim 1, wherein the second carbon-based material includes secondary particles.

3. The secondary battery according to claim 1, wherein the degree of graphitization of the second carbon-based material is less than the degree of graphitization of the first carbon-based material.

4. The secondary battery according to claim 1, wherein the gram capacity of the second carbon-based material is smaller than the gram capacity of the first carbon-based material.

5. The secondary battery according to claim 1, wherein the second carbon-based material includes at least one of artificial graphite and natural graphite.

6. The secondary battery according to claim 1, wherein the second carbon-based material satisfies at least one of the following (1) to (8). (1) The degree of graphitization of the second carbon-based material is 90.0%–95.5%, (2) The powder OI value of the second carbon-based material is 2.0-6.5, (3) The volume distribution particle size Dv50 of the second carbon-based material is 10.0 μm - 22.0 μm, (4) The particle size distribution (Dv90 - Dv10) / Dv50 of the second carbon-based material is 1.65 or less. (5) The tap density of the second carbon-based material is 0.85 g / cm³ ３ -1.25 g / cm ３ And, (6) The gram capacity of the second carbon-based material is 340 mAh / g - 360 mAh / g, (7) The specific surface area of ​​the second carbon-based material is 2.5 m². ２ / g or less, (8) The second carbon-based material satisfies I Ｄ / I Ｇ ≥ 0.280, where I Ｄ represents the D peak intensity at 1350 ± 50 cm －１ in the Raman spectrum, and I Ｇ represents the G peak intensity at 1580 ± 50 cm －１ in the Raman spectrum.

7. The secondary battery according to claim 1, wherein the first carbon-based material has a carbon coating layer on at least a portion of its surface.

8. The first carbon-based material has a thickness of 0.15 μm. ２ The secondary battery according to claim 1, comprising one or more pore structures having the above-mentioned pore area.

9. The first carbon-based material comprises an outer region and an inner region located inside the outer region, wherein the outer region is a region formed by extending a distance of 0.25 L from the particle surface of the first carbon-based material into the particle interior, where L is the short axis length of the first carbon-based material particle, and S is the total pore area of ​​the outer region. １ The total pore area of ​​the internal region is set to S. ２ Toshi, S ２ > S １ The secondary battery according to claim 1.

10. The area of ​​the pore structure in the external region of the first carbon-based material is 0.15 μm². ２ The following and / or, The internal region of the first carbon-based material is 0.15 μm. ２ The secondary battery according to claim 9, comprising one or more pore structures having the above area.

11. The secondary battery according to claim 1, wherein the first carbon-based material includes primary particles.

12. The first carbon-based material has a ratio of 0.152 ≤ I Ｄ / I Ｇ Satisfying ≤ 0.280, I Ｄ This is the Raman spectrum at 1350 ± 50 cm⁻¹. －１ This represents the D-peak intensity at I Ｇ This is the Raman spectrum at 1580 ± 50 cm⁻¹. －１ The secondary battery according to claim 1, representing the G-peak intensity in [location].

13. The secondary battery according to claim 1, wherein the X-ray diffraction pattern of the first carbon-based material has diffraction peaks on the 3R phase 101 crystal plane.

14. The secondary battery according to claim 1, wherein the X-ray diffraction pattern of the first carbon-based material does not have diffraction peaks on the 3R phase 012 crystal plane.

15. The secondary battery according to claim 1, wherein the first carbon-based material satisfies at least one of the following (1) to (10). (1) The specific surface area of ​​the first carbon-based material is 1.0 m². ２ / g-2.1m ２ / g, (2) The volume distribution particle size Dv50 of the first carbon-based material is 8.0 μm - 25.0 μm, (3) The volume distribution particle size Dv90 of the first carbon-based material is 16.0 μm - 45.0 μm, (4) The particle size distribution (Dv90 - Dv10) / Dv50 of the first carbon-based material is 1.55 or less. (5) The powder compression density of the first carbon-based material under a pressing force of 20,000 N is 1.65 g / cm³. ３ -2.0 g / cm ３ And, (6) The tap density of the first carbon-based material is 0.85 g / cm³ ３ -1.30 g / cm ３ And, (7) The gram capacity of the first carbon-based material is 355 mAh / g or more. (8) The degree of graphitization of the first carbon-based material is 95.5% or higher. (9) In a thermogravimetric analysis test of the first carbon-based material under an air atmosphere, the weight loss rate of the first carbon-based material between 35°C and 790°C was 52% or less. (10) In a thermogravimetric analysis test of the first carbon-based material under an air atmosphere, the maximum weight loss rate of the first carbon-based material is 5.0% / min or less.

16. The secondary battery according to claim 1, wherein the first active material further comprises a third carbon-based material containing artificial graphite in primary particle form.

17. The secondary battery according to claim 16, wherein the artificial graphite in primary particle form does not have a carbon coating layer on its surface.

18. The secondary battery according to claim 16, wherein the mass ratio of the third carbon-based material to the first active material is 70% by weight or less.

19. The secondary battery according to claim 16, wherein the third carbon-based material satisfies at least one of the following (1) to (7). (1) The degree of graphitization of the third carbon-based material is 92.5%–95.5%, (2) The powder OI value of the third carbon-based material is 4.5-11.5, (3) The particle size distribution (Dv90 - Dv10) / Dv50 of the third carbon-based material is 1.65 or less. (4) The volume distribution particle size Dv50 of the third carbon-based material is 12.0 μm - 22.0 μm, (5) The specific surface area of ​​the third carbon-based material is 1.0 m². ２ / g-2.0m ２ / g, (6) The tap density of the third carbon-based material is 0.95 g / cm³. ３ -1.25 g / cm ３ And, (7) The gram capacity of the third carbon-based material is 350 mAh / g - 363 mAh / g.

20. The secondary battery according to claim 1, wherein the first region and / or the second region further comprises a silicon-based material.

21. The secondary battery according to claim 1, wherein the intermediate region located between the first region and the second region includes the first active material and / or the second active material.

22. The secondary battery according to claim 1, wherein the negative electrode film layer satisfies at least one of the following (1) to (5). (1) The porosity of the negative electrode film layer is 18.0%-36.7%, (2) The compressed density of the negative electrode film layer is 1.45 g / cm³ ３ -1.90 g / cm ３ And, (3) The surface density of the negative electrode film layer is 5.0 mg / cm² ２ -25.0mg / cm ２ And, (4) The OI value of the negative electrode film layer is 35.0 or less. (5) The thickness of the negative electrode film layer is 70 μm to 250 μm.

23. A power consumption device comprising a secondary battery according to any one of claims 1 to 22.

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