CN-121698335-B - System and method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, single-walled carbon nanotubes and battery

Abstract

The invention discloses a system and a method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, the single-walled carbon nanotubes and a battery, and relates to the technical field of materials. The system comprises a plasma evaporation unit, a magnetic field screening unit and a CVD growth unit which are sequentially communicated, wherein the magnetic field screening unit comprises a magnetic field screening cavity, a temperature regulating and controlling component and a magnetic field generating component, the magnetic field screening unit is arranged between the plasma evaporation unit and the CVD growth unit, and is used for screening catalyst particles through magnetic field application and temperature control, the unit is used for selectively screening out large-particle-diameter catalyst particles, retaining small-particle-diameter catalyst particles, accurately regulating and controlling the particle size distribution of the catalyst particles, reducing the defect density and ash content of single-wall carbon nanotubes from the source, breaking through the bottleneck of the traditional process in the mass preparation of single-wall carbon nanotubes, and remarkably improving the purity and structural consistency of products.

Inventors

• LIU QIJIE
• GAO ZHIFEI
• ZHANG LIPING
• WANG CHENGBIN
• TAN YUANZHONG
• LIU DONGREN
• LIU FANG

Assignees

• 溧阳紫宸新材料科技有限公司

Dates

Publication Date

20260505

Application Date

20260213

Claims (20)

1. 1. A system for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, which is characterized by comprising a plasma evaporation unit, a magnetic field screening unit and a CVD growth unit which are sequentially communicated, wherein: The plasma evaporation unit is used for evaporating ferromagnetic catalyst materials and forming catalyst particles; The magnetic field screening unit comprises a magnetic field screening cavity, a temperature regulating and controlling component and a magnetic field generating component, wherein the temperature regulating and controlling component is used for regulating the magnetic field screening cavity to a preset temperature, the magnetic field generating component is used for applying a magnetic field to the catalyst particles and selectively screening out the catalyst particles which keep ferromagnetism at the preset temperature by utilizing whether the catalyst particles lose ferromagnetism at the preset temperature; the CVD growth unit is used for receiving the catalyst particles in the screened target particle size range and enabling the catalyst particles to react with the carbon source cracking gas in a contact way to grow single-walled carbon nanotubes; And determining the preset temperature according to the relation between the particle size of the catalyst particles and the Curie temperature and the target particle size range.
2. 2. The system of claim 1, wherein the temperature regulation assembly comprises a first interlayer water cooling member disposed about the magnetic field screening cavity and a thermocouple extending through a sidewall of the magnetic field screening cavity and into the magnetic field screening cavity in a radial direction of the magnetic field screening cavity.
3. 3. The system of claim 2, wherein the magnetic field generating assembly comprises an electromagnet located outside of the first sandwich water-cooled member.
4. 4. The system of claim 3, wherein the iron core of the electromagnet is selected from at least one of a soft magnet, a permanent magnet, or a superconducting magnet, wherein the permanent magnet is selected from at least one of neodymium iron boron, ferrite, samarium cobalt, or alnico, and wherein the superconducting magnet is selected from at least one of yttrium barium copper oxide or bismuth strontium calcium copper oxide.
5. 5. A system according to claim 3, wherein the electromagnet is wound with an induction coil having a number of turns of 1500-2000.
6. 6. The system of claim 1, wherein the magnetic field screening unit is connected to a control unit for controlling the opening and closing of the magnetic field screening unit.
7. 7. The system of claim 1, wherein the plasma evaporation unit comprises a plasma evaporation chamber, a carrier gas inlet, a gas dispersion member, a cathode hollow graphite member, and an anode graphite member, wherein: One end of the plasma evaporation chamber is communicated with the magnetic field screening cavity.
8. 8. The system of claim 7, wherein the carrier gas inlet is disposed at an end of the plasma evaporation chamber remote from the magnetic field screening unit, and is disposed at an end wall of the plasma evaporation chamber in an axial direction of the system.
9. 9. The system of claim 7, wherein the cathode hollow graphite member extends through the plasma evaporation chamber sidewall in a radial direction of the system, opposite the anode graphite member.
10. 10. The system of claim 7, wherein the anode graphite member is disposed inside the plasma vaporization chamber and opposite the cathode hollow graphite member.
11. 11. The system of claim 7, wherein the gas dispersing member is in communication with a carrier gas inlet, disposed within the plasma vaporization chamber, and is located on a side of the oppositely disposed anode graphite member and cathode hollow graphite member remote from the magnetic field screening unit.
12. 12. The system of claim 7, wherein the gas dispersing member comprises 10-30 uniformly arranged gas dispersing holes having a diameter of 1-3 mm.
13. 13. The system of claim 7, wherein the gas dispersing member has a porous disk shape with a cross-sectional shape selected from any one of circular, square, triangular, and rectangular.
14. 14. The system of claim 1, wherein the CVD growth unit comprises a CVD growth chamber, a carbon source gas inlet, a gas barrier, and a heating element, wherein: One end of the CVD growth cavity is communicated with the magnetic field screening cavity.
15. 15. The system of claim 14, wherein the carbon source gas inlet is disposed on a side proximate to the magnetic field screening unit.
16. 16. The system of claim 14, wherein the gas barrier is configured to preheat gas entering the CVD growth chamber from the carbon source gas inlet.
17. 17. The system of claim 14, wherein the heating element is configured to heat the CVD growth chamber.
18. 18. The system of claim 14, wherein a plurality of carbon source gas inlets are provided, the plurality of carbon source gas inlets being disposed circumferentially uniformly along the CVD growth chamber sidewall.
19. 19. The system of claim 14, wherein the gas barrier is cylindrical and is positioned inside the CVD growth chamber and spaced from the chamber side walls of the CVD growth unit by a gap, and the carbon source gas inlet is positioned in the gap such that gas flowing out of the carbon source gas inlet flows through the gap to be preheated and then enters the reaction zone of the CVD growth chamber to contact the catalyst for reaction.
20. 20. The system of claim 14, wherein the gas barrier is a high temperature ceramic material selected from at least one of corundum or silicon nitride.

Description

System and method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, single-walled carbon nanotubes and battery Technical Field The invention relates to the technical field of materials, in particular to a system and a method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, the single-walled carbon nanotubes and a battery. Background Single-wall carbon nanotubes (SWCNTs) are one-dimensional nanomaterials formed by crimping single-layer graphene, and have ultrahigh mechanical strength (> 100 GPa), excellent conductivity (10 6 S/cm) and unique optical characteristics, and have great application potential. However, industrialization is limited by the bottlenecks of the traditional preparation technology for a long time, such as low yield (< 1 g/h) of methods of arc discharge, laser ablation and the like, high energy consumption, and the mixing of multi-wall tubes and amorphous carbon in products, and the traditional Chemical Vapor Deposition (CVD) method can regulate and control the growth, but the catalyst is easy to sinter and deactivate, so that continuous mass production is difficult to realize. The plasma CVD method is used for evaporating metal catalysts such as iron, cobalt, nickel and the like by utilizing ultra-high temperature plasma in a macro-evaporation way, condensing to form nano catalyst aerogel, and providing a stable growth environment by combining Chemical Vapor Deposition (CVD) to realize the efficient synthesis of the single-walled carbon nanotubes. The method combines the advantages of instantaneous high temperature of plasma and controllable growth of CVD, breaks through the bottleneck of the traditional process in mass preparation, remarkably improves the purity and structural consistency of the product, and is the core research and development direction of the current industrialized mass production. When a plasma Chemical Vapor Deposition (CVD) method is used for preparing single-wall carbon nanotubes on a large scale, in the stage of condensing to form a nano catalyst after evaporating a metal catalyst by using plasma, the size of catalyst particles is difficult to control accurately, the problem that the catalyst size distribution is wide (different from a few nanometers to hundreds of nanometers) exists, the defect of a product is increased (GD ratio is reduced) and ash is increased due to the oversized catalyst, and the process difficulty of subsequent purification is increased. Therefore, how to realize the control of the catalyst particle size, improve the quality of the single-walled carbon nanotubes and finally realize the large-scale production is a technical problem to be solved in the field. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a system and a method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, the single-walled carbon nanotubes and a battery, so as to solve or improve the technical problems. The invention is realized in the following way: In a first aspect, the present invention provides a system for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, the system comprising a plasma evaporation unit, a magnetic field screening unit, and a CVD growth unit in communication in sequence, wherein: the plasma evaporation unit is used for evaporating the ferromagnetic catalyst material and forming catalyst particles; The magnetic field screening unit comprises a magnetic field screening cavity, a temperature regulating and controlling component and a magnetic field generating component, wherein the temperature regulating and controlling component is used for regulating the magnetic field screening cavity to a preset temperature, the magnetic field generating component is used for applying a magnetic field to the catalyst particles, and selectively screening out the catalyst particles which keep ferromagnetism at the preset temperature by utilizing whether the catalyst particles lose ferromagnetism at the preset temperature; The CVD growth unit is used for receiving the catalyst particles in the screened target particle size range and enabling the catalyst particles to react with the carbon source cracking gas in a contact way to grow the single-walled carbon nanotubes; The preset temperature is determined according to the relation between the particle size of the catalyst particles and the Curie temperature and the target particle size range. In a second aspect, the present invention provides a method for preparing single-walled carbon nanotubes by magnetic field assisted plasma CVD, using a system as in any of the preceding embodiments. In a third aspect, the invention provides a single-walled carbon nanotube made using a system as in any of the preceding embodiments or a method as in any of the preceding embodiments. In a fourth aspect, the present invention provides a battery c