Bidirectional high-heat-conductivity composite film with three-dimensional interpenetrating heat-conducting network and preparation method of bidirectional high-heat-conductivity composite film
A three-dimensional porous graphene framework was prepared by means of an improved Hummers method and an ice template method. Combined with chemical vapor deposition and gradient temperature vacuum hot pressing process, a two-way high thermal conductivity composite film with a three-dimensional interpenetrating thermal conductive network was prepared. This solved the problem of low thermal conductivity of graphene film in the vertical direction, achieved efficient two-way thermal conductivity, and improved the heat dissipation capability of electronic devices.
Patent Information
- Application Number
- CN202511858686.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-02-10
AI Technical Summary
Existing graphene films have excellent thermal conductivity in the in-plane direction, but their thermal conductivity is low in the direction perpendicular to the lattice plane. Furthermore, the introduction of nanoparticles or one-dimensional nanomaterials leads to a decrease in in-plane thermal conductivity and density, making it difficult to meet the heat dissipation requirements of high-power, highly integrated electronic devices.
Graphene oxide was prepared by an improved Hummers method, a three-dimensional porous graphene framework was formed by ice template method, and vertically oriented carbon nanotubes were grown by chemical vapor deposition. Combined with gradient heating vacuum hot pressing process, a bidirectional high thermal conductivity composite film with a three-dimensional interpenetrating thermal network was prepared to enhance the interfacial and longitudinal thermal conductivity.
It achieves a significant improvement in both in-plane and out-of-plane thermal conductivity, reduces interfacial contact thermal resistance, and improves the heat dissipation performance of electronic devices.
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Figure CN121492471A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of heat-conducting films, and particularly relates to a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal network and a preparation method thereof. BACKGROUND
[0002] With the rapid development of 5G communication and artificial intelligence, electronic devices with high power and high integration will generate ultra-high heat flux density during operation, resulting in a decrease in device performance, service life and reliability. Thermal interface materials (TIMs) are widely used between heat sources and heat sinks to eliminate temperature differences. Graphene is considered one of the most promising thermal interface materials due to its ultra-high thermal conductivity of 3500-5300 W / (m·K) and excellent mechanical strength.
[0003] So far, a large number of studies have focused on high-thermal-conductivity graphene films (GFs) usually assembled by graphene oxide (GO) sheets, which can be prepared by casting, vacuum filtration, electrospray deposition or evaporation-induced assembly of GO aqueous solution. High-thermal-conductivity GFs can be prepared by further reduction, carbonization, graphitization and cold pressing of GO films. During the preparation process, graphene sheets tend to be oriented and distributed in a single direction, especially under high pressure. Sp2 hybridized carbon atoms allow phonons to be efficiently transmitted in the in-plane direction. Therefore, GFs composed of layered stacked graphene sheets have excellent in-plane thermal conductivity and show broad application prospects as high-performance heat sinks in thermal management systems. However, the weak van der Waals coupling between adjacent graphene sheets will cause serious phonon scattering in the direction perpendicular to the lattice plane. This makes the in-plane thermal conductivity of traditional graphene films 2-3 orders of magnitude lower than the out-of-plane direction. To maximize the thermal conductivity of thermoelectric materials, not only high in-plane thermal conductivity but also enhanced interfacial thermal conductivity is needed between the contact surfaces of graphene. The preparation method of vertical graphene structure has been reported, which exhibits ultra-high interfacial thermal conductivity. However, the surface rigidity of vertical graphene will lead to a decrease in in-plane thermal conductivity and an increase in contact thermal resistance, so this structure is still not suitable for thermal interface materials. The in-plane thermal conduction path created by forming a three-dimensional thermal conduction network is considered an efficient solution, which can further expand the application of graphene fibers in the field of thermal interface materials. Researchers have tried to introduce nanoparticles, such as copper nanoparticles, gold nanoparticles and SiO2@C nanoparticles, or one-dimensional nanomaterials, such as carbon nanotubes, silicon carbide nanorods and carbon nanorings, into the interlayer of graphene sheets to enhance the thermal conduction in the in-plane direction. However, the intercalation of nanoparticles inevitably leads to a decrease in density and an increase in microgap, resulting in a decrease in in-plane thermal conductivity. During the directional compression process, one-dimensional nanofillers tend to be oriented in the parallel direction of the graphene lattice plane, resulting in damage to the thermal conduction bridge structure.
[0004] To this end, the inventors provide a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal conduction network and a preparation method thereof, to obtain a material with high thermal conduction performance and improve the heat dissipation performance of electronic devices with high power and high integration. SUMMARY
[0005] The present application aims to provide a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal conduction network and a preparation method thereof, to solve the problems raised in the background art. The specific technical solutions are as follows:
[0006] The first object of the present application is to provide a preparation method of a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal conduction network, which comprises the following steps:
[0007] Step 1: preparing graphene oxide by improved Hummers method;
[0008] Step 2: forming a three-dimensional porous graphene skeleton with directional pores by ice template method;
[0009] Step 3: directionally growing vertically oriented carbon nanotubes on the three-dimensional porous graphene skeleton by chemical vapor deposition method, to form a three-dimensional graphene-carbon nanotube interpenetrating network structure;
[0010] Step 4: preparing a graphene-carbon nanotube composite film with a high-density continuous pure carbon structure by gradient temperature vacuum hot pressing process of the three-dimensional graphene-carbon nanotube interpenetrating network structure;
[0011] Step 5: taking the graphene-carbon nanotube composite film as an intermediate layer, bonding graphene films on both sides of the graphene-carbon nanotube composite film by an intermediate phase, and preparing a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal conduction network by gradient temperature vacuum hot pressing process.
[0012] Preferably, the intermediate phase is pitch.
[0013] Preferably, in steps 4 and 5, the gradient temperature vacuum hot pressing process comprises the following steps: placing the material to be hot pressed in a vacuum hot pressing device, applying a pressure of 8-12 MPa under a vacuum environment of 10 -2 Pa, heating to 1400℃ at a rate of 5-10℃ / min, then heating to 1800℃ at a rate of 2-5℃ / min, keeping the temperature for 1-3 hours, and then cooling to room temperature to obtain the target material.
[0014] Preferably, in step 1, the improved Hummers method for preparing graphene oxide comprises the following steps: mixing graphite powder, concentrated sulfuric acid and sodium nitrate under ice bath conditions, adding potassium permanganate in batches at a rate of 30-60 seconds per batch, controlling the reaction temperature to be no more than 10℃, and then sequentially performing water washing, acid washing and deionized water washing to obtain a purified graphene oxide dispersion.
[0015] Preferably, in step 2, the formation of the three-dimensional porous graphene skeleton with oriented pores by the ice template method comprises the following steps: mixing the graphene oxide in the graphene oxide solution of 2.0-4.0 mg / ml with L-ascorbic acid at a mass ratio of 1:2, ultrasonic dispersion, pre-reduction at 90-95 DEG C for 20-30 minutes, freeze-drying at-18 DEG C to-20 DEG C for 3-5 hours, and then reduction at 95-100 DEG C for 5-6 hours.
[0016] Preferably, in step 3, the vertical carbon nanotubes are grown on the three-dimensional porous graphene skeleton by the chemical vapor deposition method, which comprises the following steps: placing the three-dimensional graphene skeleton in a tube furnace, using toluene, tetraethyl orthosilicate and silicon tetrachloride as precursors, and gradient pyrolysis activation at 200-1000 DEG C; then using 5-10 mg / ml ethyl ferrocene as a catalyst and a mixture of xylene / ethanol / ethylenediamine at a volume ratio of 49:49:2 as a carbon source, carbon nanotubes are grown at 850 DEG C by injection method with an injection rate of 10-20 ml / h to precisely control the growth density and vertical growth of the carbon nanotubes, to ensure that the carbon nanotubes are uniformly embedded in the graphene skeleton to form a continuous network, and a three-dimensional graphene-carbon nanotube interpenetrating network structure is formed.
[0017] The second object of the present application is to provide a bidirectional high-thermal-conductivity composite film with a three-dimensional interpenetrating thermal conduction network prepared by any of the above methods, comprising a central layer, an adhesive layer and an outer layer, the two sides of the central layer being connected to the outer layer through the adhesive layer; wherein,
[0018] The intermediate layer is a graphene-carbon nanotube composite film with a high-density continuous pure carbon structure.
[0019] The outer layer is a graphene film.
[0020] Preferably, the adhesive layer is a binder material that can be graphitized under the conditions of the gradient temperature vacuum hot pressing process.
[0021] Preferably, the adhesive layer is pitch.
[0022] Beneficial effects:
[0023] The present application utilizes the high surface thermal conductivity of the graphene film, the thickness and high longitudinal thermal conductivity of the graphene / carbon nanotube composite film, the adhesive and high thermal conductivity of the pitch graphitization, and the gradient temperature vacuum hot pressing process to reduce the porosity inside the material, thereby promoting densification and increasing the longitudinal thermal conductivity, and the hot pressing promotes integration and reduces the interface thermal resistance, thereby achieving a stepwise improvement in bidirectional thermal conductivity, greatly improving the in-plane thermal conductivity and the out-of-plane thermal conductivity, and obtaining a material with high-efficiency thermal conductivity, which improves the heat dissipation performance of high-power and high-integration electronic devices. BRIEF DESCRIPTION OF DRAWINGS
[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description only only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on these drawings.
[0025] Figure 1 is a 100 times SEM image of the three-dimensional porous graphene skeleton prepared in step 2 of Example 1;
[0026] Figure 2 is a 100 times SEM image of the three-dimensional graphene-carbon nanotube interpenetrating network structure prepared in step 3 of Example 1;
[0027] Figure 3 is a 667 times SEM image of the three-dimensional graphene-carbon nanotube interpenetrating network structure prepared in step 3 of Example 1;
[0028] Figure 4 is a 2000 times SEM image of the three-dimensional graphene-carbon nanotube interpenetrating network structure prepared in step 3 of Example 1;
[0029] Figure 5 is a 1600 times SEM image of the graphene-carbon nanotube composite film of the high-density continuous pure carbon structure after step 4 in Example 1;
[0030] Figure 6 is a 19200 times SEM image of the graphene-carbon nanotube composite film of the high-density continuous pure carbon structure after step 4 in Example 1. DETAILED DESCRIPTION
[0031] Example 1
[0032] comprising the following steps:
[0033] 1) Preparation of graphene oxide by improved Hummers method: graphite powder, concentrated sulfuric acid, sodium nitrate are mixed under ice bath condition, potassium permanganate is added in batches at a rate of 30-60 seconds per time, the reaction temperature is controlled not to exceed 10℃, then water washing, acid washing and deionized water washing are sequentially carried out to obtain a purified graphene oxide dispersion solution;
[0034] 2) Formation of a three-dimensional porous graphene framework with oriented pores via the ice template method: Graphene oxide in a 2.0-4.0 mg / ml graphene oxide solution was mixed with L-ascorbic acid at a mass ratio of 1:2, ultrasonically dispersed, and pre-reduced at 90-95℃ for 20-30 minutes. Then, it was freeze-dried at -18℃ to -20℃ for 3-5 hours, followed by reduction at 95-100℃ for 5-6 hours to obtain a three-dimensional porous graphene framework, with the structure shown below. Figure 1 As shown, the internal graphene sheets are smooth and form interconnected micron-sized pores.
[0035] 3) Vertically Oriented Carbon Nanotubes (CNA) Chemical Vapor Deposition for Oriented Growth: A three-dimensional graphene framework is placed in a tube furnace and activated by gradient pyrolysis at 200-1000℃ using toluene, tetraethyl orthosilicate, and silicon tetrachloride as precursors. Subsequently, using 5-10 mg / ml ferrocene as a catalyst and a xylene / ethanol / ethylenediamine mixture (volume ratio 49:49:2) as the carbon source, carbon nanotubes are grown at 850℃ via an injection method at an injection rate of 10-20 ml / h. This precisely controls the growth density and vertical orientation of the carbon nanotubes, ensuring uniform embedding of the carbon nanotubes into the graphene framework to form a continuous network, resulting in a three-dimensional graphene-carbon nanotube interpenetrating network structure. Figure 2 As shown, with Figure 1 The comparison shows that the above steps successfully achieved uniform growth of carbon nanotubes on a three-dimensional graphene framework, and as... Figures 3-4 As shown, high-magnification SEM further reveals the excellent vertical orientation of the carbon nanotubes grown in the three-dimensional graphene framework.
[0036] 4) Gradient hot-pressing densification treatment: The three-dimensional graphene-carbon nanotube interpenetrating network structure prepared in step 3) is subjected to a vacuum of 10⁻² Pa and a pressure of 8-12 MPa. The temperature is then increased to 1400℃ at a rate of 5-10℃ / min, followed by a further increase to 1800℃ at a rate of 2-5℃ / min, and held for 1-3 hours. This gradient heating promotes carbon atom rearrangement and structural densification. The structure is then cooled to room temperature to obtain a highly dense, continuous pure carbon structure graphene-carbon nanotube composite film. The results are as follows: Figures 4-5 As shown, after the gradient heating vacuum hot pressing process, the porosity of the graphene-carbon nanotube composite film material with a high density and continuous pure carbon structure is significantly reduced, and the three-dimensional graphene / carbon nanotube network structure is more interconnected and denser, providing an efficient pathway for phonon transmission, which is the key to achieving bidirectional high thermal conductivity.
[0037] 5) Preparation of composite films:
[0038] Graphene films, graphene-carbon nanotube composite films, and mesophase phenolic resins were stacked in a vacuum hot-pressing apparatus in the order of "graphene film + mesophase + graphene-carbon nanotube composite film + mesophase + graphene film" and heated to 10°C.-2 Under vacuum conditions, apply a pressure of 8-12 MPa, raise the temperature to 1400℃ at 5-10℃ / min, then raise the temperature to 1800℃ at 2-5℃ / min, hold for 1-3 hours, and then cool to room temperature to obtain a bidirectional high thermal conductivity composite film with a three-dimensional interpenetrating thermal network.
[0039] Example 2
[0040] The difference from Example 1 is that the intermediate phase uses pitch instead of phenolic resin. Compared to traditional binders, pitch has both adhesive properties and graphitization potential. This is achieved through a process of 10... -2 Under vacuum conditions, a pressure of 8-12 MPa is applied, and the temperature is increased to 1400℃ at a rate of 5-10℃ / min, then increased to 1800℃ at a rate of 2-5℃ / min, and held for 1-3 hours. This process completes the graphitization of the asphalt, improves the thermal conductivity of the mesophase, and plays an auxiliary role in constructing longitudinal thermal conduction channels.
[0041] The thermal conductivity of the bidirectional high thermal conductivity composite film with a three-dimensional interpenetrating thermal network prepared in step 1-2 is studied below.
[0042] Table 1. Thermal conductivity study of the bidirectional high thermal conductivity composite films with three-dimensional interpenetrating thermal networks prepared in Examples 1-2.
[0043] Material In-plane thermal conductivity (W m"1K"1) Out-of-plane thermal conductivity (W m"1K"1) Thickness (pm) Density (g cm"3) Example 1 840.3 42.5 201 1.35 Example 2 978.5 58.1 232 1.57
[0044] The results show that by utilizing the high lateral thermal conductivity of graphene film, the thickness and high longitudinal thermal conductivity of graphene / carbon nanotube composite film, the adhesion and high thermal conductivity of pitch graphitization, and the gradient heating vacuum hot pressing process to reduce the porosity of the material, thereby promoting densification and increasing longitudinal thermal conductivity, and by promoting integration and reducing interfacial contact thermal resistance, a step-wise improvement in bidirectional thermal conductivity can be achieved, with significant improvements in both in-plane and out-of-plane thermal conductivity.
[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network, characterized in that, The method includes the following steps: Step 1: Prepare graphene oxide using the modified Hummers method; Step 2: Form a three-dimensional porous graphene framework with oriented pores using the ice template method; Step 3: Vertically oriented carbon nanotubes are grown on a three-dimensional porous graphene framework by chemical vapor deposition to form a three-dimensional graphene-carbon nanotube interpenetrating network structure. Step 4: The three-dimensional graphene-carbon nanotube interpenetrating network structure is processed by gradient heating vacuum hot pressing to obtain a high-density continuous pure carbon structure graphene-carbon nanotube composite film. Step 5: Using a graphene-carbon nanotube composite film as the intermediate layer, a graphene film is bonded to both sides of the graphene-carbon nanotube composite film through an intermediate phase, and a bidirectional high thermal conductivity composite film with a three-dimensional interpenetrating thermal network is prepared by gradient heating vacuum hot pressing process.
2. The method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 1, characterized in that, The intermediate phase is bitumen.
3. The method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 2, characterized in that, In steps 4 and 5, the gradient temperature vacuum hot pressing process includes the following steps: placing the material to be hot-pressed in a vacuum hot pressing device, and heating it at 10°C. -2 Under vacuum conditions, apply a pressure of 8-12 MPa, raise the temperature to 1400℃ at 5-10℃ / min, then raise the temperature to 1800℃ at 2-5℃ / min, hold for 1-3 hours, and then cool to room temperature to obtain the target material.
4. The method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 1, characterized in that, In step 1, the modified Hummers method for preparing graphene oxide includes the following steps: graphite powder, concentrated sulfuric acid, and sodium nitrate are mixed under ice bath conditions, potassium permanganate is added in batches at a rate of 30-60 seconds / time, the reaction temperature is controlled not to exceed 10°C, and then the mixture is washed with water, acid, and deionized water in sequence to obtain a purified graphene oxide dispersion.
5. The method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 1, characterized in that, In step 2, the formation of a three-dimensional porous graphene framework with oriented pores using the ice template method includes the following steps: Graphene oxide in a 2.0-4.0 mg / ml graphene oxide solution was mixed with L-ascorbic acid at a mass ratio of 1:2, ultrasonically dispersed, and pre-reduced at 90-95℃ for 20-30 minutes. It was then freeze-dried at -18℃ to -20℃ for 3-5 hours, followed by reduction at 95-100℃ for 5-6 hours.
6. The method for preparing a bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 1, characterized in that, In step 3, the vertically oriented carbon nanotubes are grown on a three-dimensional porous graphene framework by chemical vapor deposition, including the following steps: the three-dimensional graphene framework is placed in a tube furnace and activated by gradient pyrolysis at 200-1000℃ using toluene, tetraethyl orthosilicate, and silicon tetrachloride as precursors; subsequently, the carbon nanotubes are grown at 850℃ using an injection method at an injection rate of 10-20 ml / h, with 5-10 mg / ml ferrocene as a catalyst and a xylene / ethanol / ethylenediamine mixture with a volume ratio of 49:49:2 as a carbon source, to ensure uniform embedding of carbon nanotubes into the graphene framework to form a continuous network, thus forming a three-dimensional graphene-carbon nanotube interpenetrating network structure.
7. A bidirectional high thermal conductivity composite film having a three-dimensional interpenetrating thermally conductive network, prepared by the method according to any one of claims 1-6, characterized in that, It includes a core layer, an adhesive layer, and an outer layer. The two sides of the core layer are connected to the outer layer by the adhesive layer; wherein, The intermediate layer is a graphene-carbon nanotube composite film with a highly dense, continuous pure carbon structure. The outer layer is a graphene film.
8. A bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 7, characterized in that, The adhesive layer is a graphitized adhesive material that can be graphitized under gradient temperature vacuum hot pressing conditions.
9. A bidirectional high thermal conductivity composite thin film with a three-dimensional interpenetrating thermal network according to claim 8, characterized in that, The adhesive layer is asphalt.