Preparation method and application of carbon nanotube sponge / liquid metal composite material

Abstract

The invention provides a preparation method and application of a carbon nanotube sponge / liquid metal composite material. The preparation method of the carbon nanotube sponge / liquid metal composite material comprises the following steps: 1) preparing a porous carbon nanotube sponge by adopting a chemical vapor deposition method, and removing surface impurities through plasma cleaning to form a hydrophilic oxygen-containing group; 2) placing the liquid metal gallium-indium eutectic in an ethanol solution, and carrying out ultrasonic dispersion to prepare a uniform liquid metal dispersion liquid; 3) immersing the pretreated carbon nanotube sponge into the liquid metal dispersion liquid, and placing in vacuum to realize vacuum-assisted impregnation; and 4) drying the soaked carbon nanotube sponge in a drying oven at 40 DEG C, and compacting the composite material through rolling operation. According to the application of the carbon nanotube sponge / liquid metal composite material in the field of electromagnetic shielding, the conductivity and the electromagnetic shielding effectiveness of the material are remarkably improved, and the carbon nanotube sponge / liquid metal composite material has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of nanocomposites, and specifically relates to a preparation method of a composite material of carbon nanotubes (CNT) and liquid metal (eutectic gallium indium), and its multifunctional applications in the fields of electromagnetic shielding flexible electronics and the like. Background Art

[0002] To meet the growing demands of the next generation of flexible electronic devices for lightweight, flexibility, high performance, etc., the electromagnetic shielding composite materials used in flexible electronic devices also face more excellent comprehensive performance requirements and arduous challenges. Traditional metals used for electromagnetic shielding applications, such as copper and aluminum, although they have excellent electrical conductivity, cannot meet the applications of the new generation of flexible electronic devices due to defects such as easy corrosion, difficult processing and forming, and lack of flexibility. Liquid metals (such as gallium-based alloys) have both metallic conductivity, fluidity and self-healing ability, and can maintain electrical properties during deformation, showing broad application prospects in the field of flexible electronic device applications.

[0003] Currently, there have been many studies on introducing liquid metal into the substrate material to improve the electrical conductivity of the composite material, so that the composite material shows excellent electromagnetic shielding efficiency in the high-frequency electromagnetic wave band. However, due to its extremely high surface tension, liquid metal often faces the problem of non-uniform dispersion when dispersed into polymer materials to prepare composite materials, resulting in defects such as poor continuity and uniformity of the conductive network inside the composite material. Carbon nanotube sponges have both excellent mechanical properties and electrical properties due to their unique three-dimensional carbon nanotube self-supporting structure, and the carbon nanotube sponge matrix provides a uniform, continuous and efficient conductive network for the composite material.

[0004] Compared with the sacrifice of mechanical properties when traditional metal particles are compounded with carbon nanotube sponges, the compounding of liquid metal and carbon nanotube sponges can improve the mechanical properties of the composite material while still making it flexible, which is a strong competitor for the application of the next generation of flexible electronic devices.

[0005] Existing carbon nanotube sponge-based materials have deficiencies in electrical conductivity and electromagnetic shielding efficiency, which limit their applications in high-frequency electronic devices and the aerospace field. Therefore, developing a flexible, ultra-thin and highly conductive composite material to overcome the deficiencies of existing materials has become a technical problem to be solved urgently. Summary of the Invention

[0006] The purpose of the present invention is to provide a flexible, ultra-thin and highly conductive composite material to overcome the problems such as insufficient electrical conductivity and limited electromagnetic shielding efficiency of existing carbon nanotube sponge-based materials.

[0007] The preparation method of the carbon nanotube sponge / liquid metal composite material of the present invention includes the following steps:

[0008] 1) Prepare porous carbon nanotube sponges by chemical vapor deposition method, and remove surface impurities through plasma cleaning to form hydrophilic oxygen-containing groups;

[0009] 2) Place eutectic gallium-indium liquid metal in an ethanol solution and perform ultrasonic dispersion to prepare a uniform liquid metal dispersion;

[0010] 3) Immerse the pretreated carbon nanotube sponges into the liquid metal dispersion and place them in a vacuum to achieve vacuum-assisted impregnation;

[0011] 4) Dry the soaked carbon nanotube sponges in an oven at 40 °C and achieve densification of the composite material through rolling operation.

[0012] Furthermore, the particle size of the liquid metal dispersion is in the sub-micron level.

[0013] Furthermore, the thickness of the composite material is 10 - 500 μm, and the conductivity exceeds 1×10 4 S / m; the conductivity of the carbon nanotube sponge / liquid metal composite material is increased by more than 10 times compared with that of pure carbon nanotube sponges.

[0014] Furthermore, the electromagnetic shielding effectiveness of the composite material reaches a level higher than 50 dB in the X-band (8 - 12.4 GHz).

[0015] Furthermore, the composite material has flexibility and ultrathin characteristics and is suitable for electromagnetic shielding of high-frequency electronic devices;

[0016] The composite material can be used in fields such as 5G communication devices and aerospace electronic protection.

[0017] Furthermore, the power range of the ultrasonic dispersion is 20 - 100% to obtain the best liquid metal particle dispersion effect.

[0018] Furthermore, 2 - 16 g of eutectic gallium-indium liquid metal is added to every 15 mL of ethanol solution.

[0019] Even further, 2, 4, 8 or 16 g of eutectic gallium-indium liquid metal is added to every 15 mL of ethanol solution.

[0020] Furthermore, the time of vacuum-assisted impregnation is 5 - 20 minutes to ensure sufficient penetration of the liquid metal;

[0021] In addition, the application of the carbon nanotube sponge / liquid metal composite material prepared by the above-mentioned preparation method of the carbon nanotube sponge / liquid metal composite material, the multifunctional application of the composite material in fields such as electromagnetic shielding flexible electronics.

[0022] The application of the composite material in preparing a protective coating for 5G communication equipment or aerospace equipment.

[0023] Compared with traditional CNT-based materials and metal composite processes, the present invention has the following significant advantages:

[0024] 1) Greatly improved conductivity:

[0025] By introducing liquid metal into the carbon nanotube sponge through vacuum-assisted impregnation, the conductivity of the carbon nanotube sponge is greatly improved. The conductivity of LM@CNT-16 reaches 16213 S / m, which is more than [X] times higher than that of pure CNT sponge (1096 S / m).

[0026] 2) Ultra-wideband electromagnetic shielding:

[0027] It shows an efficient total electromagnetic shielding effectiveness of [X] dB in the X-band, and has a thickness advantage compared with similar materials (such as CNT / SiC composite material, with an EMI SE of 66.33 dB when the thickness is 0.3 mm).

[0028] 3) Environmentally friendly and controllable process:

[0029] The ultrasonic dispersion method disperses the liquid metal into micro-nano particles with uniform diameter, and through the vacuum-assisted impregnation method, the carbon nanotube sponge can fully and efficiently absorb the solution. The solution impregnation method has low cost and is suitable for large-scale production. Description of the Drawings

[0030] Figure 1 Shows the preparation flow chart of the composite material, demonstrating the key steps of CNT pretreatment, LM composite, and rolling of the composite sample;

[0031] Figure 2 (a)-2(b) Shows the SEM images showing that the liquid metal particles are uniformly distributed in the CNT network, and the high-resolution images show the close interfacial bonding between the liquid metal and CNT;

[0032] Figure 3 Shows the characterization of the liquid metal particles prepared by LM@CNT-16 with different ultrasonic powers and their particle size analysis;

[0033] The ultrasonic power corresponding to a1-a2 is 30%; the ultrasonic power corresponding to b1-b2 is 60%; the ultrasonic power corresponding to c1-c2 is 100%;

[0034] Figure 4 Shows the SEM characterization of the effect of rolling on the dispersion of liquid metal before and after;

[0035] a1 - a2 is LM@CNT - 2; b1 - b2 is LM@CNT - 4; c1 - c2 is LM@CNT - 8; d1 - d2 is LM@CNT - 16; where a1 - d1 correspond to the scanning images of different samples before rolling; a2 - d2 correspond to the scanning electron microscope images of different samples after rolling.

[0036] Figure 5 It shows the electromagnetic shielding effectiveness curve in the X - band, comparing the performance differences of samples with different liquid metal loadings.

[0037] Figure 6 It is a test chart for measuring the shielding effectiveness of LM@CNT - 16 in the X - band (8 - 12 GHz) using a vector network analyzer.

[0038] Figure 7 It is a test chart for measuring the shielding effectiveness of LM@CNT - 8 in the X - band (8 - 12 GHz) using a vector network analyzer. Detailed implementation mode

[0039] The present invention discloses a preparation method and electromagnetic shielding application of a carbon nanotube sponge / liquid metal composite material.

[0040] 1. Preparation technology of carbon nanotube sponge / liquid metal composite material:

[0041] Based on the three - dimensional carbon nanotube sponge with a self - supporting structure prepared by chemical vapor deposition, by dispersing liquid metal into ethanol for ultrasonic dispersion to prepare a liquid metal dispersion with a particle size of sub - micron level, and through vacuum - assisted impregnation method, the dispersed liquid metal enters into the carbon nanotube sponge interior to be uniformly dispersed, thus successfully preparing the carbon nanotube sponge / liquid metal composite material.

[0042] 2. Outstanding electromagnetic shielding application performance:

[0043] The successful introduction of liquid metal has greatly improved the conductivity of the composite material. At the same time, the results show that the improvement of conductivity enables it to also exhibit excellent performance in the field of electromagnetic shielding, showing an electromagnetic shielding effectiveness higher than 51 dB in the X - band (8 - 12.4 GHz).

[0044] The present invention realizes the introduction of eutectic gallium indium liquid metal into the carbon nanotube sponge interior to enhance the conductive network of the carbon nanotube sponge through ultrasonic dispersion treatment and vacuum - assisted impregnation method, resulting in a significant improvement in its conductivity.

[0045] At the same time, due to the improvement of the overall electrical properties of the composite material, it shows good application prospects and performance in the field of electromagnetic shielding, showing a total electromagnetic shielding effectiveness far exceeding the commercial application standard in the X - band, and also having the flexibility of the carbon nanotube sponge itself.

[0046] Detailed preparation method:

[0047] (1) Pretreatment of CNT sponge:

[0048] A porous carbon nanotube sponge was prepared by chemical vapor deposition (CVD). Surface impurities were removed by plasma cleaning (150 W, 10 minutes), and hydrophilic oxygen-containing groups were introduced to reduce the interaction between carbon nanotubes and liquid metal, enabling micro- and nano-sized liquid metal particles to smoothly enter the interior of the carbon nanotube sponge and play their roles.

[0049] (2) Preparation of copper precursor solution:

[0050] Different masses of eutectic gallium indium (GaIn) liquid metal were placed in 15 mL of ethanol solution. The ethanol solution could slow down the oxidation of the liquid metal and serve as a good dispersant for the liquid metal. The mixed solution was placed in a cell disruptor for ultrasonic dispersion to disperse the liquid metal into micro- and nano-sized droplets, forming a stable and uniform dispersion. Different concentrations of mixed solutions were prepared based on the different masses of liquid metal added previously.

[0051] (3) Vacuum-assisted impregnation:

[0052] The pretreated CNT sponge was completely immersed in the liquid metal / ethanol solution and then placed in a vacuum for 10 minutes. Subsequently, the fully soaked carbon nanotube sponge was dried in an oven at 40 °C for 2 h to allow the ethanol to slowly volatilize and mitigate the oxidation of the liquid metal under low-temperature drying.

[0053] (4) Rolling densification of composite samples:

[0054] The completely dried composite samples were slowly extruded through rolling operations to squeeze out the excess liquid metal attached to the surface and achieve densification of the carbon nanotube sponge, making the connections inside the composite samples tighter and further enhancing the electrical conductivity of the composite material.

[0055] The preparation method includes:

[0056] It covers the full process of carbon nanotube sponge pretreatment, preparation of liquid metal / ethanol solution, vacuum-assisted impregnation method, and sample drying and rolling forming. The core step includes ultrasonic dispersion of liquid metal by a cell disruptor.

[0057] Properties of the obtained material:

[0058] CNT-LM composite material with uniformly distributed liquid metal particles, with a thickness of 10 - 500 μm and an electrical conductivity exceeding 1×10 4 S / m, combining the characteristics of ultra-thin, flexible and highly conductive.

[0059] Application scope:

[0060] Electromagnetic shielding field (such as 5G communication equipment, aerospace electronic protection).

[0061] Example 1: Preparation of LM@CNT-16

[0062] 1. CNT sponge pretreatment:

[0063] Cut the carbon nanotube sponge prepared by CVD method into 3 cm × 1.5 cm blocks, place it in a plasma cleaner, and process it for 10 minutes at a power of 150 W to obtain a hydrophilic surface.

[0064] 2. Preparation of liquid metal / ethanol mixed solution:

[0065] Weigh 16 g of liquid metal (eutectic gallium indium), slowly add it to an ethanol solution containing 15 mL, and perform ultrasonic dispersion for 50 minutes under the condition of 100% ultrasonic power to obtain a liquid metal / ethanol dispersion solution with a concentration of 16 g / 15 mL.

[0066] 3. In-situ deposition of copper particles:

[0067] Immerse the CNT sponge pretreated by Plasma in the LM / ethanol solution, place it in a vacuum environment for 20 minutes, take it out, fix it in a fixture, and place it in an oven to dry at 40 °C for 2 hours to prepare carbon nanotube sponge / liquid metal.

[0068] 4. Rolling densification of negative pressure samples:

[0069] Place the carbon nanotube sponge / liquid metal under a rolling device and roll it for 20 minutes under the condition of a pressure of 1 Mpa to form a carbon nanotube sponge / liquid metal film.

[0070] Figure 1 Shows the preparation process of LM@CNT-16 in this embodiment.

[0071] Figure 2 The scanning electron microscope images in show that LM@CNT-16 was successfully prepared in this embodiment, indicating that the liquid metal particles successfully entered the interior of the carbon nanotube sponge, and it can be observed that the carbon nanotubes wrapped the liquid metal particles, creating more conductive paths.

[0072] Figure 3 The scanning electron microscope images in c1-c2 show the dispersion of liquid metal in the ethanol solution under 100% ultrasonic power in this embodiment.

[0073] Figure 4The scanning electron microscope images in d1-d2 show the successful preparation of LM@CNT-16 in this embodiment, and under the rolling operation, the distribution of liquid metal inside the carbon nanotube sponge becomes more uniform and compact;

[0074] Figure 5 It shows that the carbon nanotube sponge / liquid metal film of LM@CNT-16 prepared in this embodiment exhibits excellent total electromagnetic shielding effectiveness in the X-band of GHz, and the electromagnetic shielding effectiveness is further improved after the secondary adsorption of liquid metal.

[0075] Example 2: Preparation of LM@CNT-8

[0076] 1. CNT sponge pretreatment:

[0077] The carbon nanotube sponge prepared by CVD method was cut into 3 cm × 1.5 cm blocks and placed in a plasma cleaner. It was treated at a power of 150 W for 10 minutes to obtain a hydrophilic surface.

[0078] 2. Preparation of liquid metal / ethanol mixed solution:

[0079] Weigh 8 g of liquid metal (eutectic gallium indium), slowly add it to an ethanol solution containing 15 mL, and perform ultrasonic dispersion for 50 minutes under the condition of 100% ultrasonic power to obtain a liquid metal / ethanol dispersion solution with a concentration of 8 g / 15 mL.

[0080] 3. In-situ deposition of copper particles:

[0081] The CNT sponge pretreated by Plasma was immersed in the LM / ethanol solution and placed in a vacuum environment for 20 minutes. After taking it out, it was fixed in a fixture and placed in an oven to dry at 40 °C for 2 hours to prepare a carbon nanotube sponge / liquid metal.

[0082] 4. Rolling densification of negative pressure samples:

[0083] The carbon nanotube sponge / liquid metal was placed under a rolling device and rolled for 20 minutes under the condition of a pressure of 1 Mpa to form a carbon nanotube sponge / liquid metal film.

[0084] Figure 3 The scanning electron microscope images in c1-c2 show the dispersion of liquid metal in the ethanol solution under 100% ultrasonic power in this embodiment.

[0085] Figure 4 The scanning electron microscope images in c1-c2 show the successful preparation of LM@CNT-8 in this embodiment, and under the rolling operation, the distribution of liquid metal inside the carbon nanotube sponge becomes more uniform and compact;

[0086] Figure 5 It is shown that the LM@CNT-8 carbon nanotube sponge / liquid metal film prepared in this example exhibits excellent total electromagnetic shielding effectiveness in the X-band of GHz, and the electromagnetic shielding effectiveness is further improved after the secondary adsorption of liquid metal.

[0087] Example 3: Preparation of LM@CNT-4

[0088] 1. Pretreatment of CNT sponge:

[0089] The carbon nanotube sponge prepared by CVD method was cut into 3 cm × 1.5 cm blocks and placed in a plasma cleaner. It was treated at a power of 150 W for 10 minutes to obtain a hydrophilic surface.

[0090] 2. Preparation of liquid metal / ethanol mixed solution:

[0091] Weigh 4 g of liquid metal (eutectic gallium indium), slowly add it to an ethanol solution containing 15 mL, and perform ultrasonic dispersion for 50 minutes under the condition of 100% ultrasonic power to obtain a liquid metal / ethanol dispersion solution with a concentration of 4 g / 15 mL.

[0092] 3. In-situ deposition of copper particles:

[0093] The CNT sponge pretreated by Plasma was immersed in the LM / ethanol solution and placed in a vacuum environment for 20 minutes. After taking it out, it was fixed in a fixture and placed in an oven to dry at 40 °C for 2 hours to prepare a carbon nanotube sponge / liquid metal.

[0094] 4. Rolling densification of negative pressure samples:

[0095] The carbon nanotube sponge / liquid metal was placed under a rolling device and rolled for 20 minutes under the condition of a pressure of 1 Mpa to form a carbon nanotube sponge / liquid metal film.

[0096] Figure 3 The scanning electron microscope images in c1-c2 show the dispersion of liquid metal in the ethanol solution under 100% ultrasonic power in this example.

[0097] Figure 4 The scanning electron microscope images in b1-b2 show the successful preparation of LM@CNT-4 in this example, and the rolling operation makes the distribution of liquid metal inside the carbon nanotube sponge more uniform and compact;

[0098] Figure 5 It is shown that the LM@CNT-4 carbon nanotube sponge / liquid metal film prepared in this example exhibits excellent total electromagnetic shielding effectiveness in the X-band of GHz, and the electromagnetic shielding effectiveness is further improved after the secondary adsorption of liquid metal.

[0099] Example 4: Preparation of LM@CNT-2

[0100] 1. Pretreatment of CNT sponge:

[0101] The carbon nanotube sponge prepared by the CVD method was cut into blocks of 3 cm×1.5 cm and placed in a plasma cleaner. It was treated at a power of 150 W for 10 minutes to obtain a hydrophilic surface.

[0102] 2. Preparation of liquid metal / ethanol mixed solution:

[0103] Weigh 2 g of liquid metal (eutectic gallium indium), slowly add it to an ethanol solution containing 15 mL, and perform ultrasonic dispersion for 50 minutes under the condition of 100% ultrasonic power to obtain a liquid metal / ethanol dispersion solution with a concentration of 2 g / 15 mL.

[0104] 3. In-situ deposition of copper particles:

[0105] The CNT sponge pretreated by Plasma was immersed in the LM / ethanol solution and placed in a vacuum environment for 20 minutes. After taking it out, it was fixed in a fixture and placed in an oven to dry at 40 °C for 2 hours to prepare carbon nanotube sponge / liquid metal.

[0106] 4. Rolling densification of negative pressure samples:

[0107] The carbon nanotube sponge / liquid metal was placed under a rolling device and rolled for 20 minutes under the condition of a pressure of 1 Mpa to form a carbon nanotube sponge / liquid metal film.

[0108] Figure 3 The scanning electron microscope images in c1-c2 show the dispersion of liquid metal in the ethanol solution under 100% ultrasonic power in this example.

[0109] Figure 4 The scanning electron microscope images of a1-a2 show the successful preparation of LM@CNT-2 in this example, and the rolling operation makes the distribution of liquid metal inside the carbon nanotube sponge more uniform and compact;

[0110] Figure 5 shows that the carbon nanotube sponge / liquid metal film of LM@CNT-2 prepared in this example exhibits excellent total electromagnetic shielding effectiveness in the X-band of GHz, and the electromagnetic shielding effectiveness is further improved after secondary adsorption of liquid metal.

[0111] The application test examples of the above example products are as follows.

[0112] Application Example 1: Electromagnetic shielding application in 5G communication equipment

[0113] Experimental purpose: To verify the electromagnetic shielding performance of carbon nanotube sponge / liquid metal composite materials in 5G communication devices.

[0114] Experimental steps:

[0115] Material preparation: Prepare the LM@CNT-16 composite material using the aforementioned preparation method, with the thickness controlled at 100 μm.

[0116] Device assembly: Cut the prepared composite material into sheets of 5 cm × 5 cm and use it as the shielding layer of the 5G communication base station. Install it on the circuit board of the base station and cover the high-frequency signal transmission module.

[0117] Electromagnetic shielding performance test: Use a vector network analyzer (Keysight N5227B) to measure the electromagnetic shielding effectiveness under 5G signals (frequency range: 24 - 30 GHz).

[0118] During the test, record the change in signal intensity and calculate the shielding effectiveness.

[0119] Experimental results: The test results show that the electromagnetic shielding effectiveness of the LM@CNT-16 composite material reaches 50 dB in the 24 - 30 GHz frequency band, and it can exhibit shielding effectiveness equivalent to that of traditional shielding materials under the condition of being lighter and lower in density.

[0120] The ultra-thin characteristics of this composite material make it occupy extremely little space inside the device, making it suitable for high-density integrated 5G communication devices.

[0121] Conclusion: The carbon nanotube sponge / liquid metal composite material exhibits excellent electromagnetic shielding ability in 5G communication devices, effectively suppressing the interference of high-frequency signals and improving the stability and signal quality of communication devices.

[0122] Application example 2: Aerospace electronic protection application

[0123] Experimental purpose: To evaluate the electromagnetic shielding and thermal management performance of carbon nanotube sponge / liquid metal composite materials in the aerospace field.

[0124] Experimental steps:

[0125] Material preparation: Prepare the LM@CNT-16 composite material according to the aforementioned method, with the thickness set at 200 μm for easy application to the external coating of aerospace equipment.

[0126] Sample application: Coat the composite material on the outer shell of the electronic equipment of the unmanned aerial vehicle to form a multifunctional protective layer.

[0127] Electromagnetic shielding and thermal management performance test: Use a vector network analyzer to test the electromagnetic shielding effectiveness of the composite material in the X-band (8 - 12 GHz).

[0128] Meanwhile, a thermal imager is used to monitor the thermal management performance of the drone in a high-temperature environment to evaluate the thermal conductivity of the material.

[0129] Experimental results: The electromagnetic shielding test results show that the total shielding effectiveness of the composite material reaches 50 dB in the X-band, significantly improving the anti-interference ability of the drone.

[0130] The thermal imaging test shows that the composite material effectively reduces the operating temperature of the electronic device, and the thermal conductivity reaches as high as 500 W / (m·K), greatly improving the thermal management ability of the device.

[0131] Conclusion: The carbon nanotube sponge / liquid metal composite material exhibits excellent electromagnetic shielding and thermal management performance in aerospace electronic protection, can effectively protect electronic devices from electromagnetic interference and high temperature effects, and has broad application prospects.

[0132] The above two application examples demonstrate the specific applications of the carbon nanotube sponge / liquid metal composite material in the field of electromagnetic shielding, showing excellent performance in 5G communication devices and aerospace electronic protection respectively. These applications not only verify the practicability of the present invention, but also provide new ideas and solutions for the future technological development in related fields.

[0133] The following is the relevant content of the efficacy test example.

[0134] Efficacy Test Example 1: Electromagnetic Shielding Performance Test

[0135] The shielding effectiveness of LM@CNT-16 in the X-band (8 - 12 GHz) is measured using a vector network analyzer, and the results are as follows Figure 6 As shown, SET (50.8 dB), SEA (35.8 dB), SER (15 dB) show that the total shielding effectiveness is 50.8 dB.

[0136] Efficacy Test Example 2: Electromagnetic Shielding Test:

[0137] The shielding effectiveness of LM@CNT-8 in the X-band (8 - 12 GHz) is measured using a vector network analyzer, and the results are as follows Figure 7 As shown, SET (50.0 dB), SEA (34.3 dB), SER (15.7 dB) show that the total shielding effectiveness is 50.0 dB.

[0138] The preparation method of the novel carbon nanotube sponge / liquid metal composite material of the present invention significantly improves the electrical conductivity and electromagnetic shielding effectiveness of the material, and has broad application prospects, especially in the protection applications of high-frequency electronic devices and the aerospace field.

[0139] Through ultrasonic dispersion treatment and vacuum-assisted impregnation method, the present invention realizes the introduction of eutectic gallium-indium liquid metal into the interior of carbon nanotube sponge, significantly improving its electrical conductivity and electromagnetic shielding ability, and having good market application potential.

[0140] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a carbon nanotube sponge / liquid metal composite material, characterized in that, It includes the following steps: 1) Prepare a porous carbon nanotube sponge by chemical vapor deposition method, and remove surface impurities through plasma cleaning to form hydrophilic oxygen-containing groups; 2) Place the eutectic liquid metal gallium-indium in an ethanol solution and perform ultrasonic dispersion to prepare a uniform liquid metal dispersion; 3) Immerse the pretreated carbon nanotube sponge into the liquid metal dispersion and place it in a vacuum to achieve vacuum-assisted impregnation; 4) Dry the immersed carbon nanotube sponge in an oven at 40 °C and achieve densification of the composite material through a rolling operation.

2. The preparation method according to claim 1, characterized in that: The particle size of the liquid metal dispersion is at the submicron level.

3. The preparation method according to claim 1, characterized in that: The thickness of the carbon nanotube sponge / liquid metal composite is 10 - 500 μm, and the conductivity exceeds 1×10 4 S / m; the conductivity of the carbon nanotube sponge / liquid metal composite is more than 10 times higher than that of pure carbon nanotube sponge; The electromagnetic shielding effectiveness of the carbon nanotube sponge / liquid metal composite material reaches a level higher than 50 dB in the X-band (8 - 12.4 GHz).

4. The preparation method according to claim 1, characterized in that: The carbon nanotube sponge / liquid metal composite material has flexibility and ultrathin characteristics and is suitable for electromagnetic shielding of high-frequency electronic devices; The carbon nanotube sponge / liquid metal composite material can be used in fields such as 5G communication devices and aerospace electronic protection.

5. The preparation method according to claim 1, characterized in that: In step 2), the power range of the ultrasonic dispersion is 20 - 100%.

6. The preparation method according to claim 1, wherein: In step 2), for every 15 mL of ethanol solution, the addition of the eutectic liquid metal gallium-indium is 2 - 16 g.

7. The preparation method according to claim 5, characterized in that: In step 2), for every 15 mL of ethanol solution, the addition of the eutectic liquid metal gallium-indium is 2, 4, 8 or 16 g.

8. The preparation method according to claim 1, characterized in that: In step 3), the time of the vacuum-assisted impregnation is 5 - 20 minutes.

9. Application of the carbon nanotube sponge / liquid metal composite material prepared by the preparation method of the carbon nanotube sponge / liquid metal composite material according to any one of claims 1 - 8, characterized in that: The multifunctional application of the carbon nanotube sponge / liquid metal composite material in fields such as electromagnetic shielding flexible electronics.

10. Application of the carbon nanotube sponge / liquid metal composite material prepared by the preparation method of the carbon nanotube sponge / liquid metal composite material according to any one of claims 1 - 8, characterized in that: The application of the carbon nanotube sponge / liquid metal composite material in the preparation of 5G communication devices or the preparation of protective coatings for aerospace equipment.

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