Carbon nanotubes satisfy Equation 1: 0.004*A+0.0385R0.004*A+0.0425, wherein R is the powder resistance of the carbon nanotubes (.Math.cm), A is ln{(purity of carbon nanotube (weight %)*specific surface area (m.sup.2/g))/bulk density (kg/m.sup.3)}, wherein the specific surface area of the carbon nanotube is 320 m.sup.2/g or more, and the bulk density of the carbon nanotube is 30 kg/m.sup.3 or less. The carbon nanotubes of the present invention have both excellent dispersibility and electrical conductivity when applied as a dispersion, and thus, are particularly suitable for use as a conductive material in secondary batteries.

Heteroatom-doped carbon nanotubes, catalytic electrodes, reactors, methods of making heteroatom-doped carbon nanotubes, and methods of reducing a molecule are described. In an embodiment, the heteroatom-doped carbon nanotube comprises single atomic metal-nitrogen-carbon (M-NC) sites for use as an electrocatalyst. In an embodiment, the heteroatom-doped carbon nanotube comprises single atomic FeN bonds as active sites configured to convert carbon dioxide to carbon monoxide. In an embodiment, the active sites are disposed on an outer surface of the heteroatom-doped carbon nanotube. In an embodiment, the heteroatom-doped carbon nanotube further comprises Ni metal nanoparticles. In an embodiment, the Ni metal nanoparticles are disposed in joints of the heteroatom-doped carbon nanotube. In an embodiment, the Ni metal nanoparticles are encapsulated by graphitic carbon layers of the heteroatom-doped carbon nanotube.

A carbon nanotube dispersion composition includes carbon nanotubes (A), a dispersant (B), and a solvent (C). A particle diameter D.sub.50 at a cumulative volume of 50% according to laser diffraction particle size distribution measurement is 0.3 to 7 m, and (1) and (2) below are satisfied. (1) The dispersant (B) is a polymer that has a weight average molecular weight of 5,000 or more and 360,000 or less and includes a carboxyl group-containing structural unit derived from at least one of (meth)acrylic acid and (meth)acrylate having a carboxyl group. (2) When the particle diameter D.sub.50 at a cumulative volume of 50% according to laser diffraction particle size distribution measurement of the carbon nanotube dispersion composition is X [m], and a pH is Y, X and Y satisfy (Formula a) and (Formula b) below:

[00001]$\begin{array}{cc}Y-0.149X+4\text{.545}& \left(\mathrm{Formula}a\right)\end{array}$$\begin{array}{cc}Y-0.134X+5.140.& \left(\mathrm{Formula}b\right)\end{array}$

The present invention generally relates to a method for producing high-quality carbon nanotubes (CNTs) from readily available and cost-effective egg-derived precursors. The system comprises a precursor preparation unit capable of processing egg white and/or yolk into suitable forms for pyrolysis. This unit includes options for dehydration and grinding into powder, hydrothermal treatment for solution-based precursors, and a blender for combining egg white and yolk powders in a controlled ratio to tailor the nitrogen/carbon content of the resulting CNTs. A pyrolysis reactor subjects the precursor to catalytic pyrolysis in an inert atmosphere (e.g., Argon) at temperatures between 900 C. and 1000 C., utilizing an iron (Fe) catalyst. Downstream, a purification unit removes catalyst particles and by-products. A gas flow control system maintains the inert atmosphere within the reactor, ensuring consistent CNT formation. This system offers a sustainable and scalable approach to CNT synthesis, leveraging the unique properties of egg components.

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 m 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 disclosure provides a filter for removing contaminants from a liquid or gaseous medium including a woven or nonwoven sheet of entangled carbon nanotubes. The present disclosure also provides a method for reducing the concentration of contaminants in a liquid or gaseous medium by contacting the liquid or gaseous medium with the filter.

An electromagnetic wave absorbing sheet includes a sheet-shaped fibrous substrate and a plurality of carbon nanotubes attached to the sheet-shaped fibrous substrate. The attached amount of the carbon nanotubes in the electromagnetic wave absorbing sheet is 5 mass % or more. The electromagnetic wave absorbing sheet has a surface resistance of 20 /sq. or more.

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.

A carbon nanotube, a preparation method and use of same, a secondary battery, a battery module, a battery pack, and an electrical device are disclosed. The carbon nanotube assumes a mace structure formed of a skeleton carbon nanotube and a branched carbon nanotube, where a weight percent of the branched carbon nanotube is 70 wt % to 90 wt % based on a total weight of the carbon nanotube. The carbon nanotube is so dispersible that the carbon nanotube can be added as a conductive agent directly into a preparation system of a negative electrode plate of the secondary battery without a need for any other dispersants. In addition, the carbon nanotube is ensured to be highly conductive, thereby ensuring a high conductivity of the negative electrode plate in the secondary battery.

A catalyst, catalyst precursor, and carbon nanotubes grown using the catalyst. The catalyst includes a support comprising alumina and a cobalt species on a surface of the support, wherein cobalt is the sole active catalyst species for carbon nanotube growth. The support surface is iron-free.