Provided is a technique related to oxidized CNTs having excellent dispersion stability and dispersibility in water. The oxidized CNTs include oxidized single-walled CNTs, have a ratio of the oxidized single-walled CNTs relative to the total number of oxidized CNTs of more than 50%, and have a D′ band in a Raman spectrum.

CNT foams and methods are provided. The methods may include forming, in a non-solvent liquid, a suspension of CNTs and particles of a pyrolytic polymer; removing the non-solvent liquid; and removing the particles of the pyrolytic polymer to produce a CNT foam having cells that at least substantially correspond to the dimensions of the particles of the pyrolytic polymer. CNT foams having porous structures also are provided.

The present invention relates to a carbon nanotube having an La(100) of less than 7.0 nm when measured by XRD and a specific surface area of 100 m.sup.2/g to 196 m.sup.2/g, and an electrode and a secondary battery including the carbon nanotube.

The present invention relates to carbon nanotubes which are characterized by satisfying the requirements (1) to (3) described below. (1) An aqueous dispersion liquid of the carbon nanotubes has a pH of from 8.0 to 10.0. (2) The BET specific surface area of the carbon nanotubes is from 200 to 800 m.sup.2/g. (3) IfY is the average fiber length (nm) of the carbon nanotubes and X is the BET specific surface area (m.sup.2/g) of the carbon nanotubes, X and Y satisfy Y = -aX + b (wherein a and b represent constants, while satisfying 2.2≤a≤3.5 and 2,300≤b≤5,000).

There is provided a carbon nanotube dispersion containing carbon nanotubes, a dispersing agent, and a solvent in which the carbon nanotubes include first carbon nanotubes having an average outer diameter of 0.5 to 5 nm and second carbon nanotubes having an average outer diameter of 5 to 20 nm, and the mass ratio between the first carbon nanotubes and the second carbon nanotubes is 1:10 to 1:100.

A process for purifying raw carbon nanotubes to obtain a content in metallic impurities of between 5 ppm and 200 ppm. The process includes an increase in the bulk density of the raw carbon nanotubes via compacting to produce compacted carbon nanotubes. The process further includes sintering the compacted carbon nanotubes by undergoing thermal treatment under gaseous atmosphere in order to remove at least a portion of the metallic impurities contained in the raw carbon nanotubes, and consequently producing purified carbon nanotubes. These purified carbon nanotubes are directly usable as electronic conductors serving as basis additive to an electrode material without requiring any subsequent purification step. The electrode material can then be used to manufacture an electrode destined to a lithium-ion battery.

A conductive material dispersion includes a carbon-based conductive material, a main dispersant, an auxiliary dispersant, and a dispersion medium, wherein the main dispersant is a nitrile-based copolymer and the auxiliary dispersant is a copolymer including an oxyalkylene unit and at least one selected from the group consisting of a styrene unit and an alkylene unit.

Provided is a technique that makes it possible to cause a secondary battery to display excellent output characteristics and other characteristics. Secondary battery production is performed using a conductive material dispersion liquid that contains a conductive material, a dispersant, and a solvent. The conductive material is one or more carbon nanotubes having a specific surface area of not less than 800 m.sup.2/g and not more than 1,300 m.sup.2/g and having a volume-average particle diameter (D90) of 50 μm or less in the conductive material dispersion liquid. The dispersant is a hydrogenated acrylonitrile-butadiene copolymer having a weight-average molecular weight of 200,000 or less.

The present invention relates to a bundle-type carbon nanotube which has a bulk density of 25 to 45 kg/m.sup.3, a ratio of the bulk density to a production yield of 1 to 3, and a ratio of a tap density to the bulk density of 1.3 to 2.0, and a method for preparing the same.

In the present invention, by dry pulverizing carbon nanotubes to control wettability index of the carbon nanotubes, the maximum concentration of the carbon nanotubes that can be added to the dispersion solvent can be increased and the workability of the carbon nanotube dispersion can be improved. Further, from this, it is possible to more easily predict the maximum concentration of the carbon nanotubes that can be added to the dispersion solvent.