Disclosed is a method of purifying carbon nanotubes, including treating carbon nanotubes with an inert gas at a high temperature in a low vacuum in a reactor and obtaining ultrapure carbon nanotubes, wherein the ultrapure carbon nanotubes contain 50 ppm or less of each metal remaining therein.

Disclosed is a method of purifying carbon nanotubes, including treating carbon nanotubes with an inert gas at a high temperature in a low vacuum in a reactor and obtaining ultrapure carbon nanotubes, wherein the ultrapure carbon nanotubes contain 50 ppm or less of each metal remaining therein.

The present invention provides a conductive material for a secondary battery, and a secondary battery containing the same, the conductive material comprising carbon nanotubes, having a secondary structure in which carbon nanotube units having a diameter of 20-150 nm are entangled, having a ratio of true density to bulk density (TD/BD) of 30-120, having a metal content of 50 ppm or less, and having both excellent dispersibility and high purity, thereby being capable of improving, by increasing the conductivity within an electrode, battery performance, particularly, battery performance at room temperature and low temperature when applied to a battery.

The present invention provides a conductive material for a secondary battery, and a secondary battery containing the same, the conductive material comprising carbon nanotubes, having a secondary structure in which carbon nanotube units having a diameter of 20-150 nm are entangled, having a ratio of true density to bulk density (TD/BD) of 30-120, having a metal content of 50 ppm or less, and having both excellent dispersibility and high purity, thereby being capable of improving, by increasing the conductivity within an electrode, battery performance, particularly, battery performance at room temperature and low temperature when applied to a battery.

A method for carbon nanotube purification, preferably including: providing carbon nanotubes; depositing a mask; and/or selectively removing a portion of the mask; and optionally including removing a subset of the carbon nanotubes and/or removing the remaining mask.

A method of producing a high-density carbon nanotube aggregate includes the steps of: preparing a carbon nanotube array including a plurality of carbon nanotubes aligned on a substrate and oriented vertically to the substrate; and heating the carbon nanotube array to 2,600 C. or higher.

A method of producing a high-density carbon nanotube aggregate includes the steps of: preparing a carbon nanotube array including a plurality of carbon nanotubes aligned on a substrate and oriented vertically to the substrate; and heating the carbon nanotube array to 2,600 C. or higher.

A method for carbon nanotube purification, preferably including: providing carbon nanotubes; depositing a mask; and/or selectively removing a portion of the mask; and optionally including removing a subset of the carbon nanotubes and/or removing the remaining mask.

A nanocarbon separation method includes a step of preparing a dispersion liquid having nanocarbons dispersed therein; a step of injecting a liquid including the dispersion liquid into an electrophoresis tank so that a pH of the liquid increases from a bottom to a top in a direction of gravitational force; and a step of applying a direct current to electrodes disposed in an upper part and a lower part of the electrophoresis tank.

A nanocarbon separation method includes a step of preparing a dispersion liquid having nanocarbons dispersed therein; a step of injecting a liquid including the dispersion liquid into an electrophoresis tank so that a pH of the liquid increases from a bottom to a top in a direction of gravitational force; and a step of applying a direct current to electrodes disposed in an upper part and a lower part of the electrophoresis tank.