Composite carbon fibers

Patent metadata

Field	Value
Publication number	US-9397340-B2
Application number	US-201314047637-A
Country	US
Kind code	B2
Filing date	Oct 7, 2013
Priority date	Mar 14, 2013
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

Provided is composite carbon fibers comprising multi-walled carbon nanotubes wherein 99% by number or more of the multi-walled carbon nanotubes have a fiber diameter of not less than 5 nm and not more than 40 nm, carbon particles having a primary particle diameter of not less than 20 nm and not more than 100 nm and graphitized carbon nanofibers wherein 99% by number or more of the graphitized carbon nanofibers have a fiber diameter of not less than 50 nm and not more than 300 nm, wherein the multi-walled carbon nanotubes are homogeneously dispersed between the graphitized carbon nanofibers and the carbon particles.

First claim

The invention claimed is:

1. Composite carbon fibers, comprising:
multi-walled carbon nanotubes in which 99% by number or more of the multi-walled carbon nanotubes have a fiber diameter of not less than 5 nm and not more than 40 nm,
carbon particles having a primary particle diameter of not less than 20 nm and not more than 100 nm, and
graphitized carbon nanofibers in which 99% by number or more of the graphitized carbon nanofibers have a fiber diameter of not less than 50 nm and not more than 300 nm,
wherein the graphitized carbon nanofibers and the carbon particles are present in a space between the multi-walled carbon nanotubes untangled into a loosened state, and the multi-walled carbon nanotubes in the untangled state are entangled on the surfaces of the graphitized carbon nanofibers and the carbon particles.

2. The composite carbon fibers according to claim 1 , wherein the multi-walled carbon nanotubes in the composite carbon fibers have an aspect ratio of 200 or higher.

3. The composite carbon fibers according to claim 1 , wherein the content of the carbon particles is not less than 30% by mass and not more than 90% by mass, and the mass ratio of the multi-walled carbon nanotubes:the graphitized carbon nanofibers is 1:9 to 8:2.

4. The composite carbon fibers according to claim 1 , which do not essentially comprise multi-walled carbon nanotube aggregates having an aggregate size of 1 μm or more.

5. Aggregates comprising the composite carbon fibers according to claim 1 .

6. The aggregates comprising the composite carbon fibers according to claim 5 , wherein a 50% particle diameter (D 50 ) in volume based accumulative particle size distribution as determined by laser diffraction particle size measurements is not less than 5 μm and not more than 20 μm.

7. The aggregates comprising the composite carbon fibers according to claim 5 , wherein the viscosity ratio (v/v 0 ) of the viscosity v of first paste to the viscosity v 0 of second paste is 1.05 or more, the first paste being prepared by kneading composite carbon fiber aggregates with a liquid medium, the composite carbon fiber aggregates comprising the multi-walled carbon nanotubes, the graphitized carbon nanofibers and the carbon particles; the second paste being prepared by kneading a composition with a liquid medium, the composition being prepared by mixing the multi-walled carbon nanotubes, the graphitized carbon nanofibers and the carbon particles in the same mass ratio by dry process.

8. A battery electrode, comprising the composite carbon fibers according to of claim 1 .

9. A battery electrode, comprising the composite carbon fiber aggregates according to claim 5 .

10. The composite carbon fibers according to claim 1 , wherein the multi-walled carbon nanotubes have a tubular structure in which graphene sheets comprising carbon six membered rings are rolled in parallel to the fiber axis.

11. A method for producing the composite carbon fibers according to claim 1 , the method comprising:
mixing multi-walled carbon nanotubes in which 99% by number or more of the multi-walled carbon nanotubes have a fiber diameter of not less than 5 nm and not more than 40 nm, carbon particles having a primary particle diameter of not less than 20 nm and not more than 100 nm, graphitized carbon nanofibers in which 99% by number or more of the graphitized carbon nanofibers have a fiber diameter of not less than 50 nm and not more than 300 nm, and a solvent to obtain a mixture,
injecting the mixture into a grinding nozzle of a high-pressure dispersing device under a pressure of from 100 MPa to 250 MPa to obtain a slurry or paste, and
drying the slurry or paste for powderization.

12. The composite carbon fibers according to claim 1 , comprising no electrode active materials.

13. The composite carbon fibers according to claim 1 , comprising no dispersing agents.

14. The composite carbon fibers according to claim 1 , having a function as an electrical conductivity imparting agent.

15. The composite carbon fibers according to claim 1 , of which the water content is 0.5% by mass or less.

16. The composite carbon fibers according to claim 1 , being in the form of a dried powder.

17. The composite carbon fibers according to claim 1 , being in the form of a paste, wherein a viscosity ratio (v/v 0 ) of the viscosity v of first paste to the viscosity v 0 of second paste is 1.05 or more, the first paste being prepared by kneading an aggregates of the composite carbon fiber with a liquid medium, the second paste being prepared by kneading a composition with liquid medium, the composition being prepared by mixing the multi-walled carbon nanotubes, the graphitized carbon nanofibers and the carbon particles in the same mass ratio by dry process.

18. A positive or negative electrode for battery, the electrode comprising the composite carbon fibers according to claim 1 , a positive or negative electrode active material and a binder.

Assignees

• Showa Denko Kk

Inventors

• Yamamoto Ryuji
• Nakamura Takeshi
• Ishii Nobuaki
• Hirano Yuta

Classifications

• H01M4/5825

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• H01M4/625 Primary

  Carbon or graphite · CPC title

• H01M10/052

  Li-accumulators · CPC title

• C01B32/18

  Nanoonions; Nanoscrolls; Nanohorns; Nanocones; Nanowalls · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title