All-carbon elastic thermal interface material and method of making same

Abstract

The application discloses a kind of full-carbon elastic thermal interface materials and preparation method thereof.Full-carbon elastic thermal interface material is by graphene and carbon nanotube jointly formed, graphene and carbon nanotube are oriented along perpendicular to material surface direction. By centrifugal filtration of mixed dispersion liquid of graphene oxide and carbon nanotube preparation high orientation precursor, again interface fusion increases material overall thickness, obtains high vertical orientation graphene arrangement structure by cutting in vertical direction, finally utilizes high temperature treatment to reduce defect structure and remove functional group, obtains full-carbon thermal interface material. Utilize the high thermal conductive path of graphene and carbon nanotube in vertical direction and the mechanical characteristics brought by orientation, realize the consideration of high elasticity and high thermal conductivity, and the method is low to equipment requirement, easy to mass production, with significant application advantage.

Description

Technical Field

[0001] This invention belongs to the field of thermal management and relates to an all-carbon elastic thermal interface material and its preparation method. Background Technology

[0002] With the continuous emergence of high-end electronic products, battery heat generation has become a significant factor limiting battery capacity and charging power, highlighting the increasing importance of thermal management material development. For thermal management materials, in addition to the core thermal conductivity, mechanical properties, durability, chemical corrosion resistance, and flame retardancy are also crucial considerations. For example, in automotive battery thermal management, it is essential to enhance impact resistance, high and low temperature resistance, and flame retardancy. For 3C products, compression resistance, bending resistance, and corrosion resistance in small sizes are paramount. However, current common thermal management materials struggle to achieve a balance of these properties. For instance, polymer materials have poor heat dissipation, are prone to aging and failure, and are easily combustible; metallic materials have high density and are not resistant to chemical corrosion; and graphite materials are prone to fracture. These problems limit the development of current thermal management materials and their applications in precision electronics and new energy batteries. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a fully carbon elastic thermal interface material and its preparation method. A mixture of graphene oxide and carbon nanotubes is deposited onto a filter membrane using centrifugal filtration technology to form a horizontally oriented composite membrane. The overall thickness is increased through interfacial fusion. The membrane is then cut vertically to obtain graphene oxide-carbon nanotube composite slices with a microscopic vertically oriented structure. Finally, high-temperature carbonization yields the fully carbon elastic thermal interface material. This thermal interface material, composed of vertically oriented graphene and carbon nanotubes, provides abundant vertical thermal conduction pathways, improves the overall compressive resilience of the material, and also exhibits corrosion resistance, flame retardancy, and resistance to high and low temperatures.

[0004] Specifically, the present invention adopts the following technical solution: a fully carbon elastic thermal interface material, which has a sheet-like structure composed of graphene sheets and carbon nanotubes, wherein the graphene sheets and carbon nanotubes are perpendicular to the material surface, and the overall density is 0.2-0.32 g / cm³. 3 It has a carbon content of more than 98%.

[0005] A method for preparing an all-carbon elastic thermal interface material includes the following steps:

[0006] (1) Disperse 0.5 to 1 part by mass of graphene oxide and 5 to 10 parts by mass of carbon nanotubes evenly in 100 parts by mass of solvent to form a composite dispersion.

[0007] (2) The composite dispersion obtained in step (1) is placed in a cylinder with a filter membrane as the inner layer and a porous filter screen as the outer layer. The central axis of the cylinder is parallel to the ground. The cylinder rotates under the drive of the motor to generate centrifugal force, so that the mixture of graphene oxide and carbon nanotubes is separated from the solvent under centrifugal action, and a centrifuged product with a thickness of more than 50 μm is formed on the filter membrane. The graphene oxide-carbon nanotube composite membrane is obtained by peeling.

[0008] (3) Spray a polar solvent on the surface of the graphene oxide-carbon nanotube composite film obtained in step (2) until the surface is wetted, and stack them layer by layer until the thickness is greater than 1 cm. Then keep it at 80-150℃ and 1-30 MPa static pressure for 10-30 min to obtain a graphene oxide-carbon nanotube composite thick film.

[0009] (4) Cut the graphene oxide-carbon nanotube composite thick film obtained in step (3) along a direction perpendicular to the film surface, with a cutting spacing of 50 to 500 μm, to obtain graphene oxide-carbon nanotube composite slices.

[0010] (5) The graphene oxide-carbon nanotube composite slices obtained in step (3) are heated to 250-350°C in air and held for 5-60 min. Then, they are chemically reduced at 60-100°C in a hydrogen iodide atmosphere for 5-60 min. Finally, they are heat-treated at 0.1-1 MPa in an argon atmosphere for 1-6 h to obtain a full carbon elastic thermal interface material.

[0011] Furthermore, the carbon nanotubes described in step (1) have one or more oxygen-containing functional groups on their surface, such as carboxyl, hydroxyl, epoxy, carbonyl, and aldehyde groups. The solvents include water, DMF, DMSO, and NMP.

[0012] Further, in step (2), the pore size of the outer filter screen is no greater than 100 μm, and the pore size of the inner filter membrane is 0.2–1 μm. The cylinder rotates at a speed of 500–6000 r / min, and the inner diameter of the cylinder is greater than 20 cm.

[0013] Furthermore, the polar solvent mentioned in step (3) includes water, DMF, DMSO, and NMP.

[0014] Furthermore, the cutting methods described in step (4) include laser cutting, diamond wire cutting, and blade circular cutting.

[0015] In this invention, the thermal conductivity test employs a vertical equivalent thermal conductivity test, referencing the standard ASTM D5470, to determine the material's thermal conductivity under actual application conditions. Unlike the thermal conductivity in this invention, the equivalent heat loss rate fully considers interfacial thermal resistance, providing feedback on the overall interfacial thermal conductivity effect under real-world conditions.

[0016] The beneficial effects of this invention are as follows:

[0017] (1) The strategy of “centrifugal filtration + interface fusion + vertical cutting” achieves the common vertical orientation of graphene oxide and carbon nanotubes. Centrifugal filtration enables graphene oxide and carbon nanotubes to be oriented in a direction parallel to the filter membrane. After multi-layer interface fusion, vertical cutting and high-temperature graphitization, the vertical orientation of graphene and carbon nanotubes can provide abundant normal heat conduction channels and make full use of the high in-plane strength of graphene and the axial rigidity of carbon nanotubes to achieve high compressive resilience.

[0018] (2) Under centrifugal filtration, graphene sheets are arranged in parallel to form an oriented structure, while carbon nanotubes are oriented along the circumferential direction of the cylinder. Thus, in the graphene oxide-carbon nanotube composite film, both carbon materials are arranged in the in-plane direction of the film, providing a structural basis for achieving high vertical thermal conductivity and high compression resilience.

[0019] (3) The solvent permeation rate of centrifugal filtration is fast, and rapid drying of the film and controllable recovery of solvent are achieved without high temperature heating, which significantly improves the preparation efficiency. During this process, under the action of centrifugal force, the material is uniform and tightly stacked, without skin effect and stress concentration, which helps to prepare thick and highly oriented films, reduces the number of film stacking interfaces, and is more conducive to the structural integrity of thermal interface materials.

[0020] (4) Applying a certain pressure to the thermal interface sheet during the high-temperature process can suppress material foaming and improve the orientation of the thermal interface material; at the same time, it can promote the fusion of the sheets and increase the density. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the production equipment used in the preparation method of the all-carbon elastic thermal interface material of the present invention. 1 is a filter membrane, 2 is a cylinder composed of a porous filter screen, 3 is the holes on the cylinder, and 4 is the central axis of the cylinder.

[0022] Figure 2 This is a physical image of the all-carbon elastic thermal interface material of Example 1;

[0023] Figure 3 This is a scanning electron microscope (SEM) image of the cross-section of the all-carbon elastic thermal interface material in Example 1.

[0024] Figure 4 This is a scanning electron microscope image of the surface of the all-carbon elastic thermal interface material in Example 1. Detailed Implementation

[0025] The present invention will be specifically described below through embodiments. These embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential changes and adjustments made by those skilled in the art based on the above-described invention shall fall within the scope of protection of the present invention.

[0026] Example 1

[0027] (1) 0.5 parts by mass of graphene oxide and 10 parts by mass of carboxylated carbon nanotubes are dispersed evenly in 100 parts by mass of DMF to form a composite dispersion.

[0028] (2) The composite dispersion obtained in step (1) is placed in a centrifuge cylinder. The inner layer of the centrifuge cylinder is a filter membrane with a pore size of 1 μm, and the outer layer is a porous filter screen with a pore size of 50 μm. The inner diameter of the cylinder is 25 cm, and the central axis of the cylinder is parallel to the ground. The cylinder rotates under the drive of the motor to generate centrifugal force. The rotation speed is 6000 r / min, so that the mixture of graphene oxide and carboxylated carbon nanotubes is separated from the solvent under centrifugal action, and a centrifuged product with a thickness of 60 μm is formed on the filter membrane. The graphene oxide-carbon nanotube composite membrane is obtained by peeling.

[0029] (3) Spray DMF onto the surface of the composite film obtained in step (2) until the surface is wetted, stack them layer by layer until the thickness is greater than 1 cm, and then keep it at 150°C and 1 MPa static pressure for 10 min to obtain a graphene oxide-carbon nanotube composite thick film.

[0030] (4) The composite thick film obtained in step (3) is laser-cut in a direction perpendicular to the film surface with a cutting spacing of 50 μm to obtain graphene oxide-carbon nanotube composite slices.

[0031] (5) The composite slice obtained in step (4) is heated to 250°C in air and held for 60 min, then chemically reduced at 60°C for 60 min in a hydrogen iodide atmosphere, and finally heat-treated at 0.1 MPa at 2600°C for 6 h in an argon atmosphere to obtain a full carbon elastic thermal interface material.

[0032] Equipment used such as Figure 1 As shown. The appearance of the obtained all-carbon elastic thermal interface material is as follows. Figure 2 As shown, it has a black, sheet-like structure. Its microstructure is as follows. Figure 3 , 4 As shown, the side view reveals a structure in which graphene sheets and nanotubes are oriented in the same direction. Figure 3 ), viewed from the top, it exhibits a typical bundle-like structure, with carbon nanotubes protruding from the edges. Figure 4 The overall density of the material is 0.2 g / cm³. 3 It has a carbon content of 99.6%, a vertical equivalent thermal conductivity of 33 W / mK, and a recovery rate of 94% after 1000 compression and rebound cycles at 0.1 MPa.

[0033] Example 2

[0034] (1) 1 part by mass of graphene oxide and 5 parts by mass of hydroxylated carbon nanotubes are dispersed evenly in 100 parts by mass of NMP to form a composite dispersion.

[0035] (2) The composite dispersion obtained in step (1) is placed in a centrifuge tube. The inner layer of the centrifuge tube is a filter membrane with a pore size of 1 μm and the outer layer is a porous filter screen with a pore size of 70 μm. The inner diameter of the tube is 30 cm and the central axis of the tube is parallel to the ground. The tube rotates under the drive of the motor to generate centrifugal force at a speed of 6000 r / min. The mixture of graphene oxide and hydroxylated carbon nanotubes is separated from the solvent under centrifugal action, and a centrifuged product with a thickness of 60 μm is formed on the filter membrane. The graphene oxide-carbon nanotube composite membrane is obtained by peeling.

[0036] (3) Spray water on the surface of the composite film obtained in step (2) until the surface is wet, stack the layers until the thickness is greater than 1 cm, and then keep it at 80°C and 10 MPa static pressure for 30 min to obtain graphene oxide-carbon nanotube composite thick film.

[0037] (4) The composite thick film obtained in step (3) is laser-cut in a direction perpendicular to the film surface with a cutting spacing of 100 μm to obtain graphene oxide-carbon nanotube composite slices.

[0038] (5) The composite slice obtained in step (4) is heated to 300°C in air and held for 30 min, then chemically reduced at 60°C for 60 min in a hydrogen iodide atmosphere, and finally heat-treated at 0.5 MPa at 2600°C for 6 h in an argon atmosphere to obtain a full carbon elastic thermal interface material.

[0039] The overall density of the obtained all-carbon elastic thermal interface material is 0.28 g / cm³. 3 It has a carbon content of 99.2%, a vertical equivalent thermal conductivity of 39 W / mK, and a recovery rate of 86% after 1000 compression and rebound cycles at 0.1 MPa.

[0040] Example 3

[0041] (1) 0.5 parts by mass of graphene oxide and 5 parts by mass of carboxylated carbon nanotubes are dispersed evenly in 100 parts by mass of water to form a composite dispersion.

[0042] (2) The composite dispersion obtained in step (1) is placed in a centrifuge cylinder. The inner layer of the centrifuge cylinder is a filter membrane with a pore size of 0.2 μm, and the outer layer is a porous filter screen with a pore size of 40 μm. The inner diameter of the cylinder is 30 cm, and the central axis of the cylinder is parallel to the ground. The cylinder rotates under the drive of the motor to generate centrifugal force at a speed of 500 r / min, so that the mixture of graphene oxide and carboxylated carbon nanotubes is separated from the solvent under centrifugal action, and a centrifuged product with a thickness of 100 μm is formed on the filter membrane. The graphene oxide-carbon nanotube composite membrane is obtained by peeling.

[0043] (3) Spray water on the surface of the composite film obtained in step (2) until the surface is wet, stack the layers until the thickness is greater than 1 cm, and then keep it at 100°C and 30 MPa static pressure for 30 min to obtain graphene oxide-carbon nanotube composite thick film.

[0044] (4) Cut the composite thick film obtained in step (3) with diamond wire cutting perpendicular to the film surface, with a cutting spacing of 500 μm, to obtain graphene oxide-carbon nanotube composite slices.

[0045] (5) The composite slice obtained in step (4) is heated to 350°C in air and held for 5 min, then chemically reduced at 100°C for 5 min in a hydrogen iodide atmosphere, and finally heat-treated at 1 MPa for 2 h in an argon atmosphere at 2600°C to obtain a full carbon elastic thermal interface material.

[0046] The overall density of the obtained all-carbon elastic thermal interface material is 0.32 g / cm³. 3 It has a carbon content of 99.4%, a vertical equivalent thermal conductivity of 45 W / mK, and a recovery rate of 91% after 1000 compression and rebound cycles at 0.1 MPa.

[0047] Example 4

[0048] (1) 0.8 parts by mass of graphene oxide and 10 parts by mass of carboxylated carbon nanotubes are dispersed evenly in 100 parts by mass of water to form a composite dispersion.

[0049] (2) The composite dispersion obtained in step (1) is placed in a centrifuge cylinder. The inner layer of the centrifuge cylinder is a filter membrane with a pore size of 0.5 μm and the outer layer is a porous filter screen with a pore size of 100 μm. The inner diameter of the cylinder is 50 cm and the central axis of the cylinder is parallel to the ground. The cylinder rotates under the drive of the motor to generate centrifugal force. The rotation speed is 2000 r / min, so that the mixture of graphene oxide and carboxylated carbon nanotubes is separated from the solvent under centrifugal action. A centrifuged product with a thickness of 80 μm is formed on the filter membrane. The graphene oxide-carbon nanotube composite membrane is obtained by peeling.

[0050] (3) Spray DMSO onto the surface of the composite film obtained in step (2) until the surface is wetted, stack the layers until the thickness is greater than 1 cm, and then keep it at 100°C and 10 MPa static pressure for 20 min to obtain a graphene oxide-carbon nanotube composite thick film.

[0051] (4) Cut the composite thick film obtained in step (3) into a circular cut with a blade perpendicular to the film surface, with a cutting spacing of 200 μm, to obtain graphene oxide-carbon nanotube composite slices.

[0052] (5) The composite slice obtained in step (4) is heated to 350°C in air and held for 20 min, then chemically reduced at 80°C for 15 min in a hydrogen iodide atmosphere, and finally heat-treated at 0.1 MPa at 2600°C for 1 h in an argon atmosphere to obtain a full carbon elastic thermal interface material.

[0053] The overall density of the obtained all-carbon elastic thermal interface is 0.23 g / cm³. 3 It has a carbon content of 98.8%, a vertical equivalent thermal conductivity of 36 W / mK, and a recovery rate of 92% after 1000 compression and rebound cycles at 0.1 MPa.

Claims

1. A method for preparing an all-carbon elastic thermal interface material, characterized in that, Includes the following steps: (1) Disperse 0.5-1 parts by mass of graphene oxide and 5-10 parts by mass of carbon nanotubes evenly in 100 parts by mass of solvent to form a composite dispersion. (2) The composite dispersion obtained in step (1) is placed in a centrifuge cylinder. The centrifuge cylinder is a rigid cylinder with a filter membrane as the inner layer and a porous filter screen as the outer layer. The central axis of the cylinder is parallel to the ground. The cylinder rotates under the drive of the motor to generate centrifugal force, so that the mixture of graphene oxide and carbon nanotubes is separated from the solvent under centrifugal action, and a centrifuged product with a thickness of more than 50 μm is formed on the filter membrane. After peeling, a graphene oxide-carbon nanotube composite membrane is obtained. The rotation speed of the cylinder in step (2) is 500-6000 r / min, and the inner diameter of the cylinder is greater than 20 cm. (3) Spray a polar solvent on the surface of the graphene oxide-carbon nanotube composite film obtained in step (2) until the surface is wetted, stack them layer by layer until the thickness is greater than 1 cm, and then keep it at 80~150 ℃ and 1-30 MPa static pressure for 10~30 min to obtain a graphene oxide-carbon nanotube composite thick film. (4) Cut the graphene oxide-carbon nanotube composite thick film obtained in step (3) along a direction perpendicular to the film surface, with a cutting spacing of 50~500 μm, to obtain graphene oxide-carbon nanotube composite slices. (5) The graphene oxide-carbon nanotube composite slices obtained in step (4) are heated to 250~350 ℃ in air and held for 5~60 min. Then, they are chemically reduced at 60~100 ℃ for 5~60 min in a hydrogen iodide atmosphere. Finally, they are heat-treated at 0.1~1MPa at 2600 ℃ in an argon atmosphere for 1~6 h to obtain a full carbon elastic thermal interface material.

2. The method according to claim 1, characterized in that, The carbon nanotubes described in step (1) have one or more of the following groups on their upper surface: carboxyl, hydroxyl, epoxy, carbonyl, and aldehyde.

3. The method according to claim 1, characterized in that, The solvents mentioned in step (1) include water, DMF, DMSO, and NMP.

4. The method according to claim 1, characterized in that, The outer filter screen in step (2) has a pore size of no more than 100 μm, and the inner filter membrane has a pore size of 0.2~1 μm.

5. The method according to claim 1, characterized in that, The polar solvents mentioned in step (3) include water, DMF, DMSO, and NMP.

6. The method according to claim 1, characterized in that, The cutting methods described in step (4) include laser cutting, diamond wire cutting, and blade circular cutting.

7. The all-carbon elastic thermal interface material prepared by the method described in claim 1 has a sheet-like structure, characterized in that... Composed of graphene sheets and carbon nanotubes, with the graphene sheets and carbon nanotubes perpendicular to the material surface, the overall density ranges from 0.2 to 0.32 g / cm³. 3 It has a carbon content of more than 98%.

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