Negative electrode and secondary battery including negative electrode

Patent metadata

Field	Value
Publication number	US-12249718-B2
Application number	US-202017435820-A
Country	US
Kind code	B2
Filing date	Mar 9, 2020
Priority date	Mar 8, 2019
Publication date	Mar 11, 2025
Grant date	Mar 11, 2025

Abstract

A negative electrode includes a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material and a conductive material. The negative electrode active material includes SiO x (0≤x<2) particles and the conductive material includes secondary particles in which a portion of one graphene sheet is connected to a portion of an adjacent graphene sheet and a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are coupled to each other, wherein the oxygen content of the secondary particles is 1 wt % to 10 wt % based on the total weight of the secondary particles, the specific surface area of the secondary particles measured by a nitrogen adsorption BET method is 500 m 2 /g to 1100 m 2 /g, and the carbon nanotube structure is included in the negative electrode active material layer in an amount of an 0.01 wt % to 1.0 wt %.

First claim

The invention claimed is:

1. A negative electrode comprising a negative electrode active material layer,
wherein the negative electrode active material layer includes a negative electrode active material and a conductive material,
wherein the negative electrode active material includes SiO x (0≤x<2) particles, and
the conductive material includes:
secondary particles comprise a plurality of graphene sheets arranged in different directions, wherein a portion of a graphene sheet is connected to a portion of an adjacent graphene sheet; and
a carbon nanotube structure in which 2 to 5,000 single-walled carbon nanotube units are bonded side by side in a single plane and,
wherein an oxygen content of the secondary particles is 1 wt % to 10 wt % based on a total weight of the secondary particles, and
a specific surface area of the secondary particles measured by a nitrogen adsorption BET method is 500 m 2 /g to 1100 m 2 /g.

2. The negative electrode of claim 1 , wherein the secondary particles comprises a structure in which the graphene sheets are coupled to each other in a chain shape.

3. The negative electrode of claim 1 , wherein a lateral size of the graphene sheet is 10 nm to 300 nm.

4. The negative electrode of claim 1 , wherein the secondary particles have a value of 0 to 0.2 as calculated by Equation 1 below:



b
-
a



a

[

Equation
⁢

⁢
1

]

wherein, a is a specific surface area (m 2 /g) of the secondary particles measured by a nitrogen adsorption BET method and b is an iodine adsorption value (mg/g) of the secondary particles.

5. The negative electrode of claim 1 , wherein the secondary particles further comprise a connection portion connected to at least some graphene sheets of the plurality of graphene sheets, wherein the connection portion is in a non-graphene form.

6. The negative electrode of claim 5 , wherein at least a portion of each of the plurality of graphene sheets is connected to the connection portion.

7. The negative electrode of claim 1 , wherein an average thickness of the graphene sheets is 0.34 nm to 10 nm.

8. The negative electrode of claim 1 , wherein a D/G peak ratio is 0.9 to 2.0 when measuring the Raman spectrum for the second particles.

9. The negative electrode of claim 1 , wherein the carbon nanotube structures are connected to each other in a net structure in the negative electrode.

10. The negative electrode of claim 1 , wherein an average length of the carbon nanotube structure is 1 μm to 500 μm.

11. The negative electrode of claim 1 , wherein an average length of the carbon nanotube structure is 6 μm to 20 μm.

12. The negative electrode of claim 1 , wherein an average diameter of the carbon nanotube structure is 2 nm to 200 nm.

13. The negative electrode of claim 1 , wherein the carbon nanotube structure is a carbon nanotube structure in which 15 to 50 single-walled carbon nanotube units are coupled to each other.

14. The negative electrode of claim 1 , wherein a weight ratio of the secondary particles to the carbon nanotube structure is 100:1 to 100:200.

15. The negative electrode of claim 1 , wherein the negative electrode active material layer further comprises carboxy methyl cellulose.

16. The negative electrode of claim 15 , wherein a weight average molecular weight of the carboxy methyl cellulose is 50,000 g/mol to 500,000 g/mol.

17. The negative electrode of claim 15 , wherein a degree of substitution of the carboxy methyl cellulose is 0.1 to 3.

18. The negative electrode of claim 1 , wherein the conductive material further comprises a multi-walled carbon nanotube unit.

19. A secondary battery comprising the negative electrode of claim 1 .

20. The negative electrode of claim 1 , wherein the carbon nanotube structure is included in the negative electrode active material layer in an amount of an 0.01 wt % to 1.0 wt %.

Assignees

• Lg Energy Solution Ltd

Inventors

• Kim Tae Gon
• Sung Ki Won
• Jung Wang Mo
• Park Sin Young
• Lee Dae Jin
• Lee Bo Ram
• Kim Hak Yoon

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title