Carbon nanotube and process for producing the carbon nanotube, and lithium ion secondary battery using the carbon nanotube

Patent metadata

Field	Value
Publication number	US-2017313586-A1
Application number	US-201515525165-A
Country	US
Kind code	A1
Filing date	Nov 12, 2015
Priority date	Nov 14, 2014
Publication date	Nov 2, 2017
Grant date	—

Abstract

The present invention relates to carbon nanotubes that are excellent in dispersibility and a process for producing the carbon nanotubes. The carbon nanotubes according to the present invention each comprise a wall that comprises a parallel portion and a narrowed portion having a tube outer diameter that is not more than 90% of a tube outer diameter of the parallel portion. Thus, the carbon nanotubes are readily dispersible owing to a high abundance ratio of easily-breaking portions.

First claim

1 . Carbon nanotubes each comprising a wall that comprises a parallel portion and a narrowed portion having a tube outer diameter that is not more than 90% of a tube outer diameter of the parallel portion,
in which when preparing a 0.1% dispersion of the carbon nanotubes, drying the dispersion on a sample table, photographing the thus dried carbon nanotubes at a magnification of 20,000 times using a transmission electron microscope to obtain a micrograph of the carbon nanotubes, dividing the micrograph into sections each having an area of 100 nm square, and selecting 300 sections each having a carbon nanotube occupied area ratio of 10 to 80%, a proportion of the sections in each of which at least one narrowed portion is present is not less than 60% among the 300 sections.

2 . The carbon nanotubes according to claim 1 , wherein a geometric mean diameter (M D ) of the tube outer diameter (D) of the carbon nanotubes is 5 to 30 nm.

3 . The carbon nanotubes according to claim 1 , wherein a geometric standard deviation (σ D ) of distribution of the tube outer diameter of the carbon nanotubes is 1.25 to 1.70.

4 . The carbon nanotubes according to claim 1 , wherein a product of a ratio of an exothermic peak temperature (T DTA ) in differential thermal analysis to a crystallite size (Lc(002)) of a (002) plane of the carbon nanotubes in X-ray diffraction analysis, and the geometric standard deviation (σ D ) of distribution of the tube outer diameter (T DTA /Lc(002))×σ D ) is not more than 22.

5 . The carbon nanotubes according to claim 1 , wherein a water vapor adsorption of the carbon nanotubes is not less than 0.6 mg/g.

6 . The carbon nanotubes according to claim 1 , wherein a total content of Al and Mg in the carbon nanotubes is 0.5 to 2.0% by weight, and a ratio of a content of Al to a content of Mg in the carbon nanotubes (Al/Mg) is 0.1 to 15.0.

7 . A process for producing the carbon nanotubes as claimed in claim 1 , in which the carbon nanotubes are produced by chemical vapor deposition reaction using a hydrocarbon gas as a raw material gas, and by using a catalyst comprising at least one element selected from the group consisting of Fe, Co, Ni and Mn, Al and Mg, a production velocity of the carbon nanotubes is controlled to not more than 0.30 g/min per 1 g of the catalyst.

8 . A lithium ion secondary battery using the carbon nanotubes as claimed in claim 1 .

Assignees

• Toda Kogyo Corp

Inventors

• Oda Wataru
• Kawai Kazushige
• Honda Tomohiro
• Okazaki Seiji
• Nagai Norimichi
• Toda Tetsuro

Classifications

• C01B2202/36

  Diameter · CPC title

• C01B2202/22

  Electronic properties · CPC title

• C01B32/162

  characterised by catalysts · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• C01P2002/70

  defined by measured X-ray, neutron or electron diffraction data · CPC title