Highly conductive carbon-coated single-walled carbon nanotube carbon mesh, and preparation method and application thereof

Abstract

The application belongs to the field of preparation of carbon nanotubes with special structure, and relates to a high-conductivity carbon-coated single-walled carbon nanotube carbon net, a preparation method and application. The method uses plasma arc discharge to prepare single-walled carbon nanotubes, uses in-situ arc discharge or high-temperature chemical vapor deposition to form a high-crystallinity carbon layer on the surface of the single-walled carbon nanotubes after treating a gaseous carbon source, and obtains a high-conductivity carbon-coated single-walled carbon nanotube carbon net with a macroscopic filamentous structure. The method can increase the purity of the product by more than 2 times and the yield by more than 3 times. Meanwhile, the high-crystallinity carbon coated on the surface of the carbon nanotubes can effectively improve the conductivity and dispersibility of the product, and the powder conductivity can reach 1.3*10 4 S·m ‑1 This method greatly saves the production cost, reduces the acid consumption for purifying unit mass of product, reduces the environmental pollution caused by waste acid, and has important application value in conductive paste and the like due to the high conductivity and good dispersibility of the product.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a highly conductive carbon-coated single-walled carbon nanotube carbon network, its preparation method, and its application. Background Technology

[0002] Single-walled carbon nanotubes (SWCNTs) have attracted continuous attention in the past due to their excellent mechanical and electrical properties. With the advancement of research, many companies are now in the industrialization preparation stage. The main difficulty in the industrialization of SWCNTs lies in the high cost and investment, and the main reason for the high cost is the low initial yield and purity.

[0003] In most current research on the preparation of single-walled carbon nanotubes using the arc discharge method, catalyst utilization is low, and a large number of fused metal catalyst particles remain in the initial product. This significant amount of residual metal catalyst increases the amount of acid used in subsequent purification processes, also increasing the cost of waste acid treatment. Furthermore, the very small diameter of individual carbon nanotubes in single-walled carbon nanotubes causes them to adhere together macroscopically, forming bundles that are difficult to disperse during application. While surface modification of carbon nanotubes can improve their dispersibility to some extent, the added additives or modification methods can damage the carbon nanotubes, affecting their conductivity and other properties. Summary of the Invention

[0004] This invention discloses a highly conductive carbon-coated single-walled carbon nanotube carbon network, its preparation method, and its application, in order to solve the above-mentioned and other potential problems of the prior art.

[0005] To solve the above problems, the technical solution of the present invention is: a highly conductive carbon-coated single-walled carbon nanotube network, which includes a single-walled carbon nanotube substrate and a highly crystalline carbon layer coated on the single-walled carbon nanotube substrate.

[0006] Furthermore, the thickness of the highly crystalline carbon layer is 50–600 nm.

[0007] Furthermore, the apparent density of the highly conductive carbon-coated single-walled carbon nanotube network is 0.03–50 mg / mL, the purity of its initial product is 70%–95%, and its yield is 50–200 g / h.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned highly conductive carbon-coated single-walled carbon nanotubes, the method comprising the following steps:

[0009] S1) Single-walled carbon nanotubes were prepared using the plasma arc method;

[0010] S2) The gaseous carbon source is treated by in-situ arc discharge or high-temperature chemical vapor deposition to form a highly crystalline carbon layer that coats the surface of the single-walled carbon nanotubes obtained in S1), resulting in a carbon network of highly conductive carbon-coated single-walled carbon nanotubes with a macroscopic filamentous structure.

[0011] Furthermore, the highly conductive carbon-coated single-walled carbon nanotube network includes a single-walled carbon nanotube substrate and a highly crystalline carbon layer coated on the single-walled carbon nanotube substrate.

[0012] The thickness of the highly crystalline carbon layer is 50–600 nm.

[0013] The apparent density of the highly conductive carbon-coated single-walled carbon nanotube network is 0.03–50 mg / mL, the purity of the initial product is 70%–95%, and the yield is 50–200 g / h.

[0014] Furthermore, the specific process of the in-situ arc discharge method is as follows:

[0015] In the process of preparing single-walled carbon nanotubes by plasma arc, a filter screen is set at the outlet to filter the gas, so that the generated single-walled carbon nanotube product remains in the furnace.

[0016] Stop the catalyst supply, maintain the electric arc, keep the temperature of the high-temperature zone in the furnace, and continuously supply a certain flow rate of gaseous carbon source and argon to complete the in-situ carbon coating.

[0017] Furthermore, the mesh size of the filter screen is 50 to 200 mesh;

[0018] The time for the generated single-walled carbon nanotubes to remain in the furnace for regrowth is 2 to 40 minutes.

[0019] The temperature in the high-temperature zone of the furnace is 900–3000℃;

[0020] The flow rate of the gaseous carbon source is 1.5–30 L / min, and the flow rate of argon is 5–150 L / min.

[0021] Furthermore, the specific steps of the high-temperature chemical vapor deposition method are as follows:

[0022] Weigh out the single-walled carbon nanotube product and place it in a quartz boat. Then place it in a tube furnace, heat it to a certain temperature, and keep it at that temperature for a certain time.

[0023] The processed single-walled carbon nanotube product was crushed to obtain a sample with a certain particle size. The sample was then placed in a quartz boat and placed in a tube furnace for reduction treatment in a hydrogen atmosphere.

[0024] The reduced sample is then heated to 1000–2800°C, and a gaseous carbon source is continuously introduced at a certain flow rate. After a certain reaction time, the carbon coating is completed.

[0025] Furthermore, the tubular furnace is heated to 300–550°C and treated with an air atmosphere for 0.5–3 hours;

[0026] The crushed particle size is 30–500 micrometers;

[0027] The reduction treatment temperature was 600–900℃, the H2 flow rate was 30–200 sccm, and the time was 0.5–3 h.

[0028] The flow rate of the carbon source methane was 50–500 sccm, and the reaction time was 0.5–2 h.

[0029] Furthermore, the highly conductive carbon-coated single-walled carbon nanotube network with a macroscopically filamentous structure has a thermal decomposition temperature as high as 708℃, and its powder conductivity reaches 1.3×10⁻⁶. 4 S·m -1 .

[0030] Furthermore, the highly conductive carbon-coated single-walled carbon nanotube mesh prepared by the method can be applied in the field of conductive pastes.

[0031] The beneficial effects of the present invention are as follows: Due to the adoption of the above technical solution, the present invention uses in-situ coating by arc discharge or high-temperature chemical vapor deposition coating, which can form a highly crystalline carbon layer at high temperature. The carbon layer uniformly coats the single-walled carbon nanotubes, forming a material with a high thermal decomposition temperature. This material structure can significantly improve the conductivity.

[0032] During the high-temperature re-growth process, the high temperature can evaporate some of the larger metal particles in the single-walled carbon nanotubes, thereby improving the yield and purity of the product and reducing the problem of treating waste acid in the later purification process.

[0033] The highly crystalline carbon layer grown at high temperature coats single-walled carbon nanotubes, which improves the wettability of the carbon nanotubes and thus effectively improves the dispersion performance of the sample.

[0034] In this invention, the carbon coating layer has a uniform thickness and complete coverage. The carbon coating layer can effectively remove the influence of catalyst particles and cover the defects inside the carbon nanotubes, resulting in a product with high crystallinity and high conductivity. Attached Figure Description

[0035] Figure 1 This is a scanning electron microscope image of the highly conductive carbon-coated single-walled carbon nanotubes prepared in Example 1 of the present invention.

[0036] Figure 2This is a transmission electron microscope image of the highly conductive carbon-coated single-walled carbon nanotubes prepared in Example 1 of the present invention.

[0037] Figure 3 This is a Raman spectrum of the highly conductive carbon-coated single-walled carbon nanotubes prepared in Example 1 of the present invention.

[0038] Figure 4 Thermogravimetric analysis curves of the highly conductive carbon-coated single-walled carbon nanotubes prepared in Example 1 of this invention.

[0039] Figure 5 This is a scanning electron microscope image of the carbon nanotubes prepared in Comparative Example 1 of the present invention.

[0040] Figure 6 This is a graph comparing the powder conductivity of the products prepared in Example 1 and Comparative Example 1 of the present invention.

[0041] Figure 7 This is a scanning electron microscope image of the highly conductive carbon-coated single-walled carbon nanotubes prepared in Example 2 of the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Example 1

[0045] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0046] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 40%.

[0047] (2) The single-walled carbon nanotube product obtained above was obtained through in-situ coating treatment within an electric arc furnace. The prepared single-walled carbon nanotubes were then coated. A 100-mesh filter was installed at the 20cm diameter outlet of the plasma electric arc furnace to filter out the reaction atmosphere, allowing the generated single-walled carbon nanotube product to remain within the furnace. The volume around the electric arc within the furnace was 0.5m³. 3In the high-temperature zone, the catalyst was stopped. When the temperature reached 1500℃, the electric arc and reaction atmosphere were maintained for another 10 minutes. After stopping, the temperature was lowered and the carbon-coated single-walled carbon nanotube sample was collected for characterization tests.

[0048] Figure 1 Scanning electron microscope (SEM) images of carbon-coated single-walled carbon nanotubes prepared under the conditions described in this example show that, based on linear carbon nanotubes, a crystalline carbon layer is completely coated on the surface. The surface of the carbon layer is smooth but irregular, the network structure composed of carbon nanotubes is not destroyed, and there are no excessive fragmented carbon blocks, indicating a very good coating effect. Figure 2 The transmission electron microscope images clearly show single-walled carbon nanotubes with a diameter of about 1.4 nm. Irregular carbon deposits on the outer wall of the carbon nanotubes can also be observed, which is related to the coating carbon layer. Figure 3 As shown in the Raman spectrum, Raman detection analysis of the product at a laser wavelength of 532 nm revealed that the sample still exhibited the characteristic RBM peaks of single-walled carbon nanotubes. Simultaneously, the results showed two distinct standard characteristic peaks for carbon materials in the spectrum: the G peak and the D peak. Calculations yielded I... G / I D The concentration was 65, and the product exhibited high crystallinity. Further analysis of the sample's thermal stability and residual amount was performed using thermogravimetric analysis. The sample was heated to 900°C in air. Figure 4 The thermogravimetric curves show that the sample only begins to decompose at 600℃, reaches its peak at 708℃, and completes decomposition only near 800℃, ultimately leaving 6.24% impurities. Because the sample underwent a second growth process using arc discharge, a highly crystalline carbon layer was formed, exhibiting a high thermal decomposition temperature. Simultaneously, some catalyst particles were evaporated at high temperature, resulting in a very low final residue. The initial purity of the sample can reach over 90%.

[0049] Comparative Example 1

[0050] Based on Example 1, no filter screen is added at the outlet of the plasma arc furnace, allowing the product to be directly discharged from the furnace. Simultaneously, a catalyst supply is continuously maintained during the growth process. In contrast to Example 1, the specific steps are as follows:

[0051] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 40%.

[0052] (2) The prepared single-walled carbon nanotubes were further reacted. The outlet of the plasma arc furnace, with a diameter of 20 cm, was kept clear to allow the product to be carried out by the gas flow. The volume around the arc inside the furnace was 0.5 m³. 3In the high-temperature zone, the catalyst was continuously introduced. When the temperature reached 1500℃, the electric arc and reaction atmosphere were maintained for another 10 minutes. After stopping, the temperature was lowered and the sample was collected for characterization tests.

[0053] Figure 5 The scanning electron microscope (SEM) image of the sample prepared under the comparative conditions shows that the sample is a bundle of carbon nanotubes, which are relatively long and straight, reaching several micrometers in length. Within the gaps between the carbon nanotubes, there are obvious catalyst particles and amorphous carbon fragments. With continuous catalyst supply and timely removal of the product from the furnace, the generated carbon nanotubes do not undergo regrowth within the furnace, and the product exhibits a relatively distinct carbon nanotube morphology. However, compared to Example 1, when the generated carbon nanotubes remain in the furnace while the catalyst supply is stopped and the carbon source supply is continuous, a highly crystalline carbon layer continues to form on the surface of the carbon nanotubes, further confirming the effectiveness of Example 1.

[0054] The powder conductivity of the products in the examples and the product in Comparative Example 1 was tested. Figure 6 The graphs show the resistivity of the two samples as a function of pressure. As pressure increases, the samples become more compact, the contact becomes tighter, and the resistivity gradually decreases. The comparison shows that the resistivity of both samples exhibits the same trend with pressure, but the overall resistivity of the sample in Example 1 is lower than that of the sample in Comparative Example 1. Calculations show that the conductivity of both samples at 18 MPa is 1.3 × 10⁻⁶. 4 S·m -1 and 6.5×10 3 S·m -1 The conductivity of single-walled carbon nanotubes coated with a highly crystalline carbon layer is increased by 2 times, resulting in high electrical conductivity. When applied to water-based conductive slurry products, they offer advantages such as high conductivity and easy dispersibility.

[0055] Example 2

[0056] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0057] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 40%.

[0058] (2) Weigh an appropriate amount of the single-walled carbon nanotube product prepared by the electric arc method, place the product in a quartz boat, and treat it in an air atmosphere at 450℃ for 2 hours in a tube furnace. The air-fired sample was then pulverized to obtain a pretreated sample with a particle size of 200 micrometers. An appropriate amount of the pretreated sample was placed in a quartz boat and then placed in a tube furnace again for reduction at 700℃ with 80 sccm of H2 for 1 hour. An appropriate amount of the reduced sample was placed in a graphite boat and placed in a high-temperature furnace. Chemical vapor deposition was performed at 2300℃ with a methane flow rate of 200 sccm for 1.5 hours. After stopping the reaction, the sample was cooled and collected to obtain a carbon-coated single-walled carbon nanotube sample for characterization.

[0059] Figure 7 The scanning electron microscope image of the carbon-coated single-walled carbon nanotubes prepared under the conditions of this example shows that the carbon nanotube substrate is still linear, and a crystalline carbon layer is completely coated on the surface of the carbon nanotube. The carbon layer is relatively coarse and thick, and there is some adhesion at the bottom. There are not too many fragmented carbon blocks, and the coating effect is very good.

[0060] It is evident that the high temperatures provided by plasma arc and chemical vapor deposition processes can both achieve the formation of carbon coating layers. Furthermore, the high temperatures provided by both processes are conducive to the formation of highly crystalline carbon layers and can also reduce the evaporation of some catalyst particles, resulting in high-purity, highly conductive carbon-coated single-walled carbon nanotube products.

[0061] Example 3

[0062] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0063] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 30%.

[0064] (2) The single-walled carbon nanotube product obtained above was obtained through in-situ coating treatment within an electric arc furnace. The prepared single-walled carbon nanotubes were then coated. A 150-mesh filter was installed at the 20cm diameter outlet of the plasma electric arc furnace to filter out the reaction atmosphere, allowing the generated single-walled carbon nanotube product to remain within the furnace. The volume around the electric arc within the furnace was 0.8m³. 3 In the high-temperature zone, the catalyst was stopped. When the temperature reached 2500℃, the electric arc and reaction atmosphere were maintained for another 20 minutes. After stopping, the temperature was lowered and the sample was collected.

[0065] Example 4

[0066] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0067] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 35%.

[0068] (2) The single-walled carbon nanotube product obtained above was treated by in-situ coating in an electric arc furnace. The prepared single-walled carbon nanotubes were coated. A 100-mesh filter was installed at the outlet of the plasma electric arc furnace with a diameter of 20 cm to filter out the reaction atmosphere, allowing the generated single-walled carbon nanotube product to remain inside the furnace. The volume around the electric arc inside the furnace was 1.0 m³. 3 In the high-temperature zone, the catalyst was stopped. When the temperature reached 2700℃, the electric arc and reaction atmosphere were maintained for another 30 minutes. After stopping, the temperature was lowered and the sample was collected.

[0069] Example 5

[0070] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0071] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 45%.

[0072] (2) The single-walled carbon nanotube product obtained above was obtained through in-situ coating treatment within an electric arc furnace. The prepared single-walled carbon nanotubes were then coated. A 150-mesh filter was installed at the 20cm diameter outlet of the plasma electric arc furnace to filter out the reaction atmosphere, allowing the generated single-walled carbon nanotube product to remain within the furnace. The volume around the electric arc within the furnace was 0.2m³. 3 In the high-temperature zone, the catalyst was stopped. When the temperature reached 2000℃, the electric arc and reaction atmosphere were maintained for another 15 minutes. After stopping, the temperature was lowered and the sample was collected.

[0073] Example 6

[0074] A highly conductive carbon-coated single-walled carbon nanotube and its preparation method, the specific steps of which are as follows:

[0075] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 60%.

[0076] (2) Weigh an appropriate amount of the single-walled carbon nanotube product prepared by the electric arc method, place the product in a quartz boat, and treat it in an air atmosphere at 350°C for 2.5 h in a tube furnace. Pulverize the air-fired sample to obtain a pretreated sample with a particle size of 300 μm. Take an appropriate amount of the pretreated sample and place it in a quartz boat, then place it back in a tube furnace and reduce it at 800°C with 100 sccm of H2 for 2 h. Take an appropriate amount of the reduced sample and place it in a graphite boat, then place it in a high-temperature furnace. Perform chemical vapor deposition reaction at 2500°C with a methane flow rate of 150 sccm for 1 h. After stopping, cool down and collect the sample.

[0077] Example 7

[0078] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0079] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 35%.

[0080] (2) Weigh an appropriate amount of the single-walled carbon nanotube product prepared by the electric arc method, place the product in a quartz boat, and treat it in an air atmosphere at 450°C for 1 hour in a tube furnace. The air-fired sample is then pulverized to obtain a pretreated sample with a particle size of 50 micrometers. An appropriate amount of the pretreated sample is placed in a quartz boat and then placed back into a tube furnace for reduction at 750°C with 50 sccm of H2 for 1.5 hours. An appropriate amount of the reduced sample is placed in a graphite boat and placed in a high-temperature furnace. Chemical vapor deposition is performed at 2000°C with a methane flow rate of 300 sccm for 1 hour. After the reaction is stopped, the sample is collected by cooling.

[0081] Example 8

[0082] A method for preparing a highly conductive carbon-coated single-walled carbon nanotube network, the specific steps of which are as follows:

[0083] (1) Single-walled carbon nanotubes were prepared by plasma arc method. The single-walled carbon nanotubes prepared by the method were tested and found to have a filamentous structure. The initial purity of the single-walled carbon nanotubes was 50%.

[0084] (2) Weigh an appropriate amount of the single-walled carbon nanotube product prepared by the electric arc method, place the product in a quartz boat, and treat it in an air atmosphere at 450°C for 1.5 h in a tube furnace. Pulverize the air-fired sample to obtain a pretreated sample with a particle size of 400 μm. Take an appropriate amount of the pretreated sample and place it in a quartz boat, then place it back in a tube furnace and reduce it by introducing 60 sccm of H2 at 850°C for 1 h. Take an appropriate amount of the reduced sample and place it in a graphite boat, then place it in a high-temperature furnace. Perform chemical vapor deposition at 1800°C with a methane flow rate of 150 sccm for 1.5 h. After stopping the reaction, cool down and collect the sample.

[0085] The foregoing has provided a detailed description of a highly conductive carbon-coated single-walled carbon nanotube network, its preparation method, and its application, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0086] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0087] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0088] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0089] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method of making a high conductive carbon web of single-walled carbon nanotubes coated with carbon, characterized by, The method specifically comprises the following steps: S1) preparing single-walled carbon nanotubes by using a plasma arc method; S2) forming a high-crystallinity carbon layer on the surface of the single-walled carbon nanotubes obtained in S1) by treating a gaseous carbon source by using an in-situ arc discharge method or a high-temperature chemical vapor deposition method, to obtain a high-conductivity carbon-coated single-walled carbon nanotube carbon net with a macroscopic filamentous structure; The specific process of the in-situ arc discharge method is as follows: During the preparation of single-walled carbon nanotubes by using a plasma arc method, a filter screen is arranged at the discharge port, the generated single-walled carbon nanotube product is filtered by the filter screen to stay in the furnace, the catalyst is stopped from being introduced, the arc is maintained, the temperature of the high-temperature zone in the furnace is maintained, a certain flow rate of the gaseous carbon source and argon is continuously introduced, and the in-situ carbon coating is completed. The mesh number of the filter screen is 50-200; 2. The method of claim 1, wherein, The single-walled carbon nanotube product stays in the furnace for 2-40 min for re-growth; The temperature of the high-temperature zone in the furnace is 900-3000℃; The flow rate of the gaseous carbon source is 1.5-30 L / min, and the flow rate of argon is 5-150 L / min. The specific steps of the high-temperature chemical vapor deposition method are as follows:

3. The method of claim 1, wherein, The single-walled carbon nanotube product is weighed and placed in a quartz boat, and then the quartz boat is placed in a tube furnace and heated to a certain temperature and maintained for a certain time; The treated single-walled carbon nanotube product is crushed to obtain a sample with a certain particle size, and then the sample is placed in a quartz boat and placed in a tube furnace for reduction treatment in a hydrogen atmosphere; The sample after reduction treatment is heated to 1000-2800℃, a certain flow rate of gaseous carbon source is continuously introduced, and the reaction is carried out for a certain time, and the carbon coating is completed. The tube furnace is heated to 300-550℃, and the air atmosphere is treated for 0.5-3 h; 4. The method of claim 3, wherein, The broken particle size is 30-500 microns; The reduction treatment temperature is 600-900℃, the flow rate of H2 is 30-200 sccm, and the time is 0.5-3 h; The flow rate of the carbon source methane is 50-500 sccm, and the reaction time is 0.5-2 h. The high-conductivity carbon-coated single-walled carbon nanotube carbon net comprises a single-walled carbon nanotube substrate and a high-crystallinity carbon layer coated on the single-walled carbon nanotube substrate, and forms a high-conductivity carbon-coated single-walled carbon nanotube carbon net with a macroscopic filamentous structure; the thickness of the high-crystallinity carbon layer is 50-600 nm; 5. The method according to any one of claims 1 to 4, characterized in that, The thermal decomposition temperature of the high-conductivity carbon-coated single-wall carbon nanotube carbon net with macroscopically filamentous structure is as high as 708 DEG C, and the powder conductivity reaches 1.3*10 4 S*m -1 .

6. The high-conductivity carbon-network single-walled carbon nanotube prepared by the method according to any one of claims 1 to 5, characterized in that, The apparent density of the high-conductivity carbon-coated single-walled carbon nanotube carbon net is 0.03-50 mg / mL, the purity of the initial product is 70%-95%, and the yield is 50-200 g / h.

7. The high-conductivity carbon-coated single-walled carbon nanotube carbon net prepared by the method of any one of claims 1-5 is applied to the field of conductive paste. ​

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