A method for preparing high thermal conductive carbon nanotube graphene film

Abstract

The application belongs to the technical field of carbon materials, and more particularly relates to a method for preparing high-thermal-conductivity carbon nanotube graphene film. The application provides a method for preparing high-thermal-conductivity carbon nanotube graphene film, which comprises the following steps: (1) dispersing carbon nanotubes, adding a graphene dispersion liquid, then adding nanowires, mixing, and obtaining a stable suspension; (2) vacuum suction filtering the suspension prepared in step (1) for 8-12 hours to obtain a mixed film; (3) drying the film prepared in step (2) and peeling it from the filter paper; (4) placing the film obtained in step (3) in a vacuum box, heating at a temperature of 1800-2500 DEG C, maintaining for 1-5 hours, taking out, and obtaining a carbon nanotube graphene film. The carbon nanotube graphene film prepared by the method has good high-temperature resistance, still has a good surface state under high-temperature treatment, and the prepared film shows good toughness and thermal conductivity.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials technology, and more specifically relates to a method for preparing highly thermally conductive carbon nanotube graphene films. Background Technology

[0002] In recent years, with the development of science and technology, macroscopic films constructed from carbon nanotubes and graphene have attracted much attention. Due to their excellent thermal conductivity, electrical conductivity, and chemical stability, carbon nanotube and graphene films have wide applications in superconducting materials, thermal conductive materials, bulletproofing, and electromagnetic shielding.

[0003] However, when carbon nanotubes and graphene are fabricated into thin films, their thermal conductivity decreases significantly, reaching only one percent of the intrinsic thermal conductivity of the carbon nanotubes and graphene themselves. This greatly limits their large-scale application in thermally conductive materials. The reason for the decreased thermal conductivity of the carbon nanotube and graphene films lies in the excessively high interfacial thermal resistance at the contact points between carbon nanotubes and between carbon nanotubes and graphene, resulting in reduced local thermal conductivity and hindered heat transfer, thus causing a decrease in overall thermal conductivity. To address this problem, researchers have attempted to graphitize the carbon nanotube-graphene films to achieve higher thermal conductivity. However, the carbon nanotube-graphene films prepared by this method exhibit significant brittleness changes, failing to meet the requirements of practical applications. Summary of the Invention

[0004] To address the problem of poor thermal conductivity in carbon nanotube-graphene films due to excessively high interfacial thermal resistance at the carbon nanotube-graphene interface, this invention provides a method for preparing highly thermally conductive carbon nanotube-graphene films, comprising the following steps: (1) Disperse carbon nanotubes, add them to graphene dispersion, then add nanowires, mix, and obtain a stable suspension; (2) Vacuum filter the suspension prepared in step (1) for 8-12 hours to obtain a mixed film; (3) Dry the film prepared in step (2) and peel it off from the filter paper; (4) Place the film obtained in step (3) in a vacuum chamber, heat it to 1800-2500℃, keep it warm for 1-5 hours, and take it out to obtain carbon nanotube graphene film.

[0005] As a preferred technical solution, the carbon nanotubes in step (1) are selected from single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0006] As a preferred technical solution, the nanowires in step (1) are selected from at least one of Ni nanowires, Pt nanowires, InP nanowires, GaN nanowires, and SiC nanowires.

[0007] As a preferred technical solution, the nanowires are selected from SiC nanowires.

[0008] As a preferred technical solution, the length of the SiC nanowires is 1-50 micrometers.

[0009] As a preferred technical solution, the length of the SiC nanowires is 5-10 micrometers.

[0010] As a preferred technical solution, the weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:2~3:2~3.

[0011] As a preferred technical solution, the weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:3:2.

[0012] As a preferred technical solution, the vacuum degree of vacuum filtration in step (2) is 0.5-1.33 Pa.

[0013] As a preferred technical solution, the heating temperature in step (4) is 2000℃.

[0014] Beneficial effects: The carbon nanotube graphene film prepared by this invention exhibits good high-temperature resistance, maintaining a good surface condition even under high-temperature treatment. Furthermore, the prepared film demonstrates good toughness and thermal conductivity. Test results show that the thermal conductivity of the carbon nanotube graphene film prepared by this invention is 1200 W / m·K, solving the problem of low thermal conductivity in existing technologies. Attached Figure Description

[0015] Figure 1 This is a test image of the flexibility of the carbon nanotube graphene film of this invention. Figure 2 This is a test diagram of the folding flexibility of the carbon nanotube graphene film of this invention. Detailed Implementation

[0016] The invention can be further understood by referring to the following detailed description of preferred embodiments and included examples. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. If the definitions of specific terms disclosed in the prior art are inconsistent with any definitions provided in this application, the definitions provided in this application shall prevail.

[0017] As used herein, unless explicitly indicated by the context, features not limited to the singular or plural forms are intended to include features in the plural form as well. It should also be understood that, as used herein, the terms “prepared from” and “comprising” are synonymous, and “comprising,” “including,” “having,” “containing,” and / or “comprising”, when used in this specification, refer to the stated composition, step, method, article, or apparatus, but do not exclude the presence or addition of one or more other compositions, steps, methods, articles, or apparatuses. Furthermore, when describing embodiments of this application, the use of “preferred,” “more preferably,” “more than,” etc., refers to embodiments of the invention that, in certain circumstances, provide certain beneficial effects. However, other embodiments may also be preferred in the same or other circumstances. Moreover, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of the invention.

[0018] To address the aforementioned technical problems, this invention provides a method for preparing highly thermally conductive carbon nanotube graphene films, comprising the following steps: (1) Disperse carbon nanotubes, add them to graphene dispersion, then add nanowires, mix, and obtain a stable suspension; (2) Vacuum filter the suspension prepared in step (1) for 8-12 hours to obtain a mixed film; (3) Dry the film prepared in step (2) and peel it off from the filter paper; (4) Place the film obtained in step (3) in a vacuum chamber, heat it to 1800-2500℃, keep it warm for 1-5 hours, and take it out to obtain carbon nanotube graphene film.

[0019] In some preferred embodiments, the carbon nanotubes in step (1) are selected from single-walled carbon nanotubes and / or multi-walled carbon nanotubes.

[0020] Carbon nanotubes, model XFM70, were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0021] The carbon nanotube dispersion method in this application involves adding a carbon nanotube aqueous dispersant.

[0022] In some preferred embodiments, the weight ratio of the carbon nanotube water dispersant to the carbon nanotubes is 0.1:1.

[0023] Carbon nanotube water dispersant, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0024] In some preferred embodiments, the nanowires in step (1) are selected from at least one of Ni nanowires, Pt nanowires, InP nanowires, GaN nanowires, and SiC nanowires.

[0025] Preferably, the nanowires are SiC nanowires.

[0026] SiC nanowires SiC nanowires are single-crystal fibers with a radial dimension of less than 100 nm and a length dimension much larger than the radial dimension. SiC materials are artificial covalent compounds, and due to their excellent high-temperature strength, high thermal conductivity, high wear resistance, and corrosion resistance, they have been widely used in aerospace, automotive machinery, chemical, and electronics industries.

[0027] Through extensive and creative experimental research, the applicant has found that adding silicified carbon nanowires to this system can significantly improve the high-temperature resistance of carbon nanotube-graphene films. During high-temperature graphitization, the surface of the carbon nanotube-graphene film shows no abnormal changes, and the film remains undamaged. The applicant speculates that this phenomenon may be due to the following: During high-temperature graphitization, SiC nanowires can be loaded between the carbon nanotubes and graphene, forming a network structure with the SiC nanowires. When SiC nanowires are subjected to high temperatures, their lattice vibration ability is restricted by the carbon nanotubes and graphene, resulting in relatively less thermal energy acquired at high temperatures and weakened molecular thermal motion. This leads to the observed improvement in high-temperature resistance after graphitization at 1800-2500℃ for 2 hours, with no abnormal changes in surface properties.

[0028] In some preferred embodiments, the SiC nanowires have a length of 1-50 micrometers.

[0029] In some preferred embodiments, the SiC nanowires have a length of 5-10 micrometers.

[0030] In some preferred embodiments, the SiC nanowires have an average diameter of 100 nm.

[0031] SiC nanowires, model XFJ56, were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0032] In the experiments, the traditional method of using high-temperature graphitization at 2000℃ to improve the thermal conductivity of the film resulted in a brittle film, limiting its application. In this application, after extensive experimental verification, it was unexpectedly discovered that using SiC nanowires with a length of 5-10 micrometers can solve this problem. The applicant speculates that the possible reason is that under high temperature, SiC nanowires, carbon nanotubes, and graphene become entangled with each other through van der Waals forces to form a porous network structure. The 5-10 micrometer-long SiC nanowires form a uniform and dense distribution within the system. When subjected to external forces, the contact surfaces can transfer stress, but the internal porous structure prevents stress transfer. Within the 5-10 micrometer length range of SiC, the balance between stress transfer and stress dissipation can be coordinated, thereby enhancing the ability of the carbon nanotube / graphene film to withstand external impacts and avoiding excessive brittleness.

[0033] In some preferred embodiments, the weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:2~3:2~3.

[0034] In some preferred embodiments, the weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:3:2.

[0035] During the experiment, the applicant unexpectedly discovered that when the weight ratio of graphene dispersion, carbon nanotubes, and SiC nanowires was 5:3:2, the prepared carbon nanotube / graphene film exhibited high thermal conductivity. The applicant speculates that the possible reason is that the 5-10 micrometer-long silicified carbon nanowires added in this application act as a bridge between the carbon nanotubes and graphene. They intertwine with the carbon nanotubes and graphene through van der Waals forces, forming a large reaction interface within the 5:3:2 weight ratio range. This interface provides efficient heat transfer sites and reduces the charge transfer resistance and particle diffusion resistance in the system, allowing for secondary charge distribution and avoiding excessive local resistance, thus ensuring the high thermal conductivity of the carbon nanotube-graphene film.

[0036] Graphene dispersion, model XF224-1, item number 102297, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0037] In some preferred embodiments, the vacuum degree of the vacuum filtration in step (2) is 0.5-1.33 Pa.

[0038] In some preferred embodiments, the vacuum degree of the vacuum filtration in step (2) is 1.33 Pa.

[0039] In some preferred embodiments, the heating temperature in step (4) is 2000°C.

[0040] In some preferred embodiments, the carbon nanotubes in step (1) are selected as multi-walled carbon nanotubes.

[0041] In this application, the applicant chose to incorporate multi-walled carbon nanotubes (MWCs), which, compared to single-walled CNCs, can further improve the impact resistance of the carbon nanotube graphene film. The applicant speculates that the possible reasons are: MWCs have more internal defects and poorer uniformity than single-walled CNCs; however, in this application, the MWCs selected can form a better composite with SiC nanowires, allowing small-diameter nanowires to be more uniformly distributed between the carbon nanotube layers. The small voids on the inner walls of the carbon nanotubes effectively disperse stress in the SiC nanowires, preventing stress concentration at defect locations and improving the flexibility of the carbon nanotube graphene film. Performance tests show that the carbon nanotube graphene film prepared in this application can withstand bending and folding without damage, demonstrating good application prospects.

[0042] Furthermore, it should be noted that the vacuum filtration method used in this application for thin film processing is based on the technical solution of this application. The carbon nanotubes, graphene, and SiC nanowires selected in this application form a stable suspension, which can be used to prepare carbon nanotube-graphene thin films via vacuum filtration. The preparation method is simple, and the prepared films meet the requirements for use and testing.

[0043] In some preferred embodiments, the carbon nanotubes, graphene dispersion, and SiC nanowires are in the following proportions by weight: 10-40 parts carbon nanotubes, 40-100 parts graphene dispersion, and 20-40 parts SiC nanowires.

[0044] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0045] In addition, unless otherwise stated, all raw materials used are commercially available.

[0046] Example Example 1 A method for preparing highly thermally conductive carbon nanotube graphene films includes the following steps: (1) Disperse carbon nanotubes, add them to graphene dispersion, then add SiC nanowires, mix, and obtain a stable suspension; (2) The suspension prepared in step (1) was vacuum filtered for 12 hours to obtain a mixed film; (3) Dry the film prepared in step (2) and peel it off from the filter paper; (4) Place the film obtained in step (3) in a vacuum chamber, heat it to 2000℃, keep it warm for 2 hours, and take it out to obtain a carbon nanotube graphene film.

[0047] In step (1), 0.3 parts of carbon nanotube water dispersant are added to disperse the nanotubes.

[0048] In step (4), it is placed in a vacuum chamber with a vacuum degree of 1.33 Pa.

[0049] The carbon nanotubes, graphene dispersion, and SiC nanowires are in the following weight proportions: 30 parts carbon nanotubes, 50 parts graphene dispersion, and 20 parts SiC nanowires.

[0050] Carbon nanotubes, model XFM70, were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; carbon nanotube water dispersant was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; SiC nanowires, model XFJ56, were purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.; graphene dispersion, model XF224-1, item number 102297, was purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0051] Example 2 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) involves adding 50 parts by weight of SiC nanowires.

[0052] Example 3 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) involves adding 5 parts by weight of SiC nanowires.

[0053] Example 4 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) involves adding SiC nanowires with a length of 50-100 micrometers, model XFJ56, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0054] Example 5 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) does not involve the addition of SiC nanowires.

[0055] Example 6 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) adds 50 parts by weight of carbon nanotubes and 0.5 parts by weight of carbon nanotube water dispersant.

[0056] Example 7 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that step (1) involves adding carbon nanotubes of type XFS28, purchased from Nanjing Xianfeng Nanomaterials Technology Co., Ltd.

[0057] Example 8 A method for preparing a high thermal conductivity carbon nanotube graphene film, which differs from Example 1 in that the heating temperature in step (4) is 2500℃.

[0058] Performance testing: 1. Thermal conductivity test: The carbon nanotube graphene films prepared in Examples 1-8 were used for thermal conductivity test. The test standard was GB / T8722-2019, and the test results are summarized in the table below.

[0059] 2. Thermal expansion coefficient test: The carbon nanotube graphene films prepared in Examples 1-8 were used to determine the thermal expansion coefficient. The thermal expansion coefficient of the films was measured using a TEA-1200 thermal expansion coefficient tester, and the test results are summarized in the table below.

[0060] 3. Material flexibility test: The flexibility of carbon nanotube graphene film was tested by rolling and folding. The film that can be rolled is considered excellent, the film with cracks on the surface after rolling is considered good, and the film that breaks after rolling is considered poor. The test results are summarized in the table below.

[0061]

[0062] The carbon nanotube graphene film prepared by this invention not only has good thermal conductivity but also good flexibility, and has good application prospects.

[0063] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the protection principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of preparing a high thermally conductive carbon nanotube graphene film, characterized by, Includes the following steps: (1) Disperse carbon nanotubes, add them to graphene dispersion, then add nanowires, mix, and obtain a stable suspension; (2) Vacuum filter the suspension prepared in step (1) for 8-12 hours to obtain a mixed film; (3) Dry the film prepared in step (2) and peel it off from the filter paper; (4) Place the film obtained in step (3) in a vacuum chamber, heat it to 1800-2500℃, keep it warm for 1-5 hours, take it out, and obtain carbon nanotube graphene film. In step (1), the carbon nanotubes are selected from multi-walled carbon nanotubes; the nanowires are selected from SiC nanowires; the length of the SiC nanowires is 5-10 micrometers; and the weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:2~3:2~3.

2. The method of claim 1, wherein the high thermal conductive carbon nanotube graphene film is characterized by, The weight ratio of the graphene dispersion, carbon nanotubes, and SiC nanowires is 5:3:

2.

3. The method for producing a high thermal conductivity carbon nanotube graphene film according to claim 1, characterized in that, The vacuum degree of the vacuum filtration in step (2) is 0.5-1.33 Pa.

4. The method for producing a high thermal conductivity carbon nanotube graphene film according to claim 1, characterized in that, The heating temperature in step (4) is 2000℃.

Images