Provided are a method of efficiently producing a fibrous carbon nanostructure dispersion liquid having high dispersibility, and a fibrous carbon nanostructure dispersion liquid having high dispersibility. A production method for a fibrous carbon nanostructure dispersion liquid comprises a step of performing continuous centrifugal separation on a solution containing fibrous carbon nanostructures and a solvent.

A fibrous carbon nanostructure dispersion liquid contains a solvent and fibrous carbon nanostructures having at least one absorption peak in a wavenumber region of 500 cm.sup.1 to 600 cm.sup.1 in a light absorption spectrum.

A positive electrode sheet for air batteries according to an embodiment of this invention comprises a waved fibrous carbon and has a BET method specific surface area in a range of 300 to 1200 m.sup.2/g, a 5 to 1000 nm-diameter pore surface area in a range of 200 to 600 m.sup.2/g, a 0.1 to 10 ?m-diameter pore volume in a range of more than 2.0 to no more than 10.0 cm.sup.3/g, a 2 to 1000 nm-diameter pore volume in a range of 1.0 to 5.0 cm.sup.3/g, and a sheet density in a range of 0.05 to 0.23 g/cm.sup.3.

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 related to oxidized carbon nanotubes having excellent dispersion stability and dispersibility in water. The oxidized carbon nanotubes include oxidized single-walled carbon nanotubes, have a ratio of the oxidized single-walled carbon nanotubes relative to the total number of oxidized carbon nanotubes of more than 50%, and have a BET specific surface area of 100 m.sup.2/g or less.

Disclosed is a method of producing surface-treated carbon nanostructures which comprises: a depressurization step wherein a carbon nanostructure-containing liquid which comprises carbon nanostructures and a dispersion medium is depressurized; and a surface treatment step wherein an oxidizing agent is added in the carbon nanostructure-containing liquid after or during the depressurization step so that the carbon nanostructures have a surface oxygen atom concentration of 7.0 at % or more. The carbon nanostructures preferably comprise carbon nanotubes.

An embodiment of the present specification provides a method for preparing a catalyst for preparing a carbon nanotube, comprising: (a) dissolving a main catalyst precursor, a support precursor, a cocatalyst precursor and a precipitation inhibitor in a solvent to prepare a precursor solution; and (b) pyrolyzing the precursor solution by spraying the precursor solution into a reactor, wherein a mole fraction of the precipitation inhibitor to the cocatalyst precursor is 0.1 to 1.5.

The present invention relates to a method for producing large-diameter, low-density carbon nanotubes. The method uses a catalyst containing spherical -alumina that is capable of controlling the growth of carbon nanotubes without deteriorating the quality of the carbon nanotubes. The use of the catalyst makes the carbon nanotubes highly dispersible.

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.