Preparation method of graphene composite phase change thermal interface material

Abstract

The application relates to a preparation method of a graphene composite phase change thermal interface material. An oxidized graphene dispersion liquid is provided, a centrifugal roller coating and a layer-by-layer drying process are adopted to form a multilayer oxidized graphene unit layer on a substrate, and an oxidized graphene film is obtained; the oxidized graphene film is placed in a limited space, gradient heat reduction treatment is carried out, the film is controllably expanded in the out-of-plane direction, and a reduced graphene oxide film with a micro-nano cavity structure is formed; the reduced graphene oxide film is subjected to graphitization treatment, and a graphene micro-nano cavity film is obtained; through a vacuum impregnation method, a molten phase change material is filled into the micro-nano cavity structure of the graphene micro-nano cavity film. The thermal interface material has high phase change enthalpy (196.2 J / g), excellent thermal performance (in-plane thermal conductivity 65.5 W.m ‑1 ·K ‑1 , out-of-plane 21.9 W.m ‑1 ·K ‑1 , and low interface thermal resistance (0.575 K.cm 2 ·W ‑1 ).

Description

Technical Field

[0001] This invention relates to the field of phase change materials technology, specifically to a method for preparing a graphene composite phase change thermal interface material. Background Technology

[0002] With the increasing integration of electronic devices, high thermal conductivity thermal interface materials (TIMs) have become crucial for solving the heat dissipation problem. Vertically aligned graphene frameworks, due to their excellent thermal conductivity potential, are considered highly promising TIM filling structures, and various three-dimensional graphene network structure fabrication techniques, such as self-assembly, template methods, and stress-induced methods, have been developed in this field. However, existing technologies face several bottlenecks: the fabricated graphene frameworks generally suffer from structural defects, and weak interactions between graphene sheets lead to high contact thermal resistance; furthermore, the small thickness of the graphene sheets within the framework easily induces severe phonon scattering at the graphene / polymer interface, resulting in excessively low room-temperature thermal conductivity even with a graphene loading >10wt%. Although some studies have shown that vertical arrays of μm-thickness graphene films can improve thermal conductivity by reducing the number of interfaces, ultra-high graphene loading can severely impair the performance of phase change materials and cannot meet the flexibility requirements of TIMs.

[0003] In recent years, the idea of ​​preparing graphene oxide thin films by solution coating and regulating interlayer expansion behavior by utilizing thermal reduction-induced gas release has been proposed. This method can simultaneously optimize the interlayer interaction and pore structure of graphene sheets. For example, Chinese invention patent application CN104724698A discloses a technique for preparing thin-layer graphene by thermal expansion, which achieves expansion by rapidly heating graphene oxide in a furnace at 250-400℃, simplifying the preparation process. However, this technique focuses on the preparation of powdered graphene and does not address the controllable regulation of the structure of thin film materials, nor does it solve the performance adaptation problem in TIMs applications. Summary of the Invention

[0004] The first aspect of this invention provides a method for preparing a graphene composite phase change thermal interface material, comprising the following steps:

[0005] S1: Provide a graphene oxide dispersion, and use a centrifugal roller coating and layer-by-layer drying process to form a multilayer graphene oxide unit layer on a substrate to obtain a graphene oxide film;

[0006] S2: The graphene oxide film is placed in a confined space and subjected to gradient thermal reduction treatment, so that the film expands controllably in the out-of-plane direction to form a reduced graphene oxide film with a micro-nano cavity structure.

[0007] S3: The reduced graphene oxide film is graphitized to obtain a graphene micro / nano cavity film;

[0008] S4: The molten phase change material is filled into the micro-nano cavity structure of the graphene micro-nano cavity film by vacuum impregnation to obtain a graphene composite phase change thermal interface material.

[0009] The volume expansion coefficient (expanded volume / initial volume) of the reduced graphene oxide film is 3-50.

[0010] Optionally, the reduced graphene oxide film has a volume expansion coefficient of 5-30.

[0011] The gradient thermal reduction process includes heating the graphene oxide film to 120-190°C at a heating rate of 0.2-0.9°C / min under 30-80 kPa, and then heating it to 300-390°C at a heating rate of 0.8-2°C / min.

[0012] Optionally, the gradient thermal reduction treatment includes: heating the graphene oxide film to 140-160°C at a heating rate of 0.4-0.6°C / min under 40-60 kPa, and then heating it to 340-360°C at a heating rate of 0.8-1.2°C / min.

[0013] This invention reveals that a centrifugal roll coating and layer-by-layer drying process achieves controllable expansion and structural integrity of reduced graphene oxide films. Conventional blade coating methods for preparing graphene oxide films suffer from limitations. Due to the large thickness of a single layer, blade coating can only form a single thick layer, hindering the release pathway of gases from the decomposition of oxygen-containing groups and suppressing orderly out-of-plane expansion. Furthermore, uneven interlayer stress distribution leads to sheet compression and aggregation. Centrifugal roll coating, through layer-by-layer thin-layer deposition, optimizes the heat-stress distribution, achieving controllable expansion and structural integrity. Its high packing density and thin-layer characteristics jointly suppress structural damage during thermal reduction. Secondly, the layer-by-layer drying strategy forms regular interfaces between adjacent unit layers, providing space for gas release. This regular interface structure also provides a basis for directional volume expansion and micro / nano cavity self-assembly. Further research shows that by limiting the specific gradient heat treatment within a confined space, the volume expansion coefficient of the reduced graphene oxide film can be maintained between 3 and 50, while the in-plane thermal diffusivity of the graphene composite phase change thermal interface material can be 700-850 mm². 2 / s, out-of-plane thermal diffusivity 30-55mm 2 / s. Volume expansion mainly occurs in the out-of-plane direction. The pore structure and interlayer spacing can be precisely controlled by the confined space, and the interlayer bridging network provides additional phonon transport paths.

[0014] Optionally, the graphitization process includes heating the reduced graphene oxide film to 2900-3100°C at a heating rate of 3-10°C / min.

[0015] The thickness of the graphene oxide film is 1-10 μm.

[0016] Optionally, the thickness of the graphene oxide film is 2-6 μm.

[0017] The density of the graphene micro / nano cavity film is 0.02-0.3 g / cm³. 3 .

[0018] Optionally, the density of the graphene micro / nano cavity film is 0.02-0.20 g / cm³. 3 .

[0019] The filling temperature is 170-190℃, and the filling time is 6-10 hours.

[0020] Optionally, the filling temperature is 175-185℃ and the filling time is 7-9h.

[0021] The phase change material includes polyols.

[0022] The polyols include at least one of Tris (tris-hydroxymethyl-aminomethane), pentaerythritol, neopentyl glycol, xylitol, and mannitol.

[0023] Optionally, the polyols include Tris.

[0024] Optionally, at least one through hole may be formed on the surface of the graphene composite phase change thermal interface material.

[0025] Optionally, the diameter of the through holes is 50-200 μm, and the number is 2-10.

[0026] A smaller volume expansion coefficient and smaller interlayer spacing result in a higher density of micro-nano cavities. This structural difference leads to significant variations in the filling rate of phase change materials during vacuum impregnation. A lower filling rate indicates a lower content of effective phase change components in the composite material. Although extending the impregnation time can significantly improve the filling rate, the unavoidable changes in vacuum level during impregnation will cause oxidation of the matrix material, and longer impregnation times may lead to more severe oxidation. Therefore, achieving both low oxidation and high filling rate in reduced graphene oxide films with short impregnation times is key to further improving their overall performance. To address this issue, this invention found that creating pores on the surface of graphene micro-nano cavity films can improve impregnation efficiency, thereby providing resistance to instantaneous thermal shock. Further research revealed that the diameter of the through-holes is 50-200 μm, and the number is 2-10. This allows the thermal interface material to possess both high phase change enthalpy (196.2 J / g) and excellent thermal properties (in-plane thermal conductivity 65.5 W·m). -1 ·K -1 21.9 W·m outwards -1 ·K -1) and low interfacial thermal resistance (0.575 K·cm) 2 ·W -1 It is speculated that large-sized through holes will lead to leakage of phase change material during the phase change process, thereby resulting in enthalpy loss.

[0027] Beneficial effects

[0028] 1. Controllable expansion and structural integrity of reduced graphene oxide films were achieved by using centrifugal roller coating and layer-by-layer drying processes.

[0029] 2. By employing specific gradient heat treatment within a confined space, the volume expansion coefficient of reduced graphene oxide films can be maintained between 3 and 50, and the in-plane thermal diffusivity can be 700-850 mm. 2 / s, out-of-plane thermal diffusivity 30-55mm 2 / s.

[0030] 3. The present invention forms at least one through hole on the surface of the graphene composite phase change thermal interface material, which can improve the impregnation efficiency, achieve low oxidation degree and high filling rate at the same time with short impregnation time, and provide resistance to instantaneous thermal shock.

[0031] 4. By limiting the size and number of through holes, this invention enables the thermal interface material to possess both high phase change enthalpy (196.2 J / g) and excellent thermal properties (in-plane thermal conductivity 65.5 W·m). -1 ·K -1 21.9 W·m outwards -1 ·K -1 ) and low interfacial thermal resistance (0.575 K·cm) 2 ·W -1 ).

[0032] 5. The composite material of this invention can meet the application requirements of thermal protection in the field of chips and electronic devices, and its performance is superior to existing graphene film pads and silicone rubber pads. Attached Figure Description

[0033] Figure 1 The images shown are electron microscope images of the graphene cross-section in Example 1, including (a) graphene oxide film, (b) reduced graphene oxide film and (c) graphene micro / nano cavity film.

[0034] Figure 2 The X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction of the graphene oxide film (GOF), reduced graphene oxide film (rGO), and graphene micro / nano cavity film (GMF) in Example 1 are shown.

[0035] Figure 3The images shown are electron microscope images of graphene micro / nano cavity films in the examples, including (a) Example 2, (b) Example 3, (c) Example 4, (d) Example 5, (e) Example 1, and (f) Example 6.

[0036] Figure 4 The images shown are electron microscope images of the reduced graphene oxide films in Example 1 and Comparative Example 1, where (a) is Example 1 and (b) is Comparative Example 1.

[0037] Figure 5 The images shown are electron microscope images of the graphene composite phase change thermal interface materials in the examples, including (a) Example 2, (b) Example 3, (c) Example 4, (d) Example 5, (e) Example 1, and (f) Example 6.

[0038] Figure 6 (a) Infrared thermal imaging of the graphene composite phase change thermal interface material in Example 3, (b) Infrared thermal imaging of the graphene composite phase change thermal interface material in Example 8, and (c) Temperature curves of the two thermal interface materials.

[0039] Figure 7 (a) Infrared thermal imaging images of the thermal interface materials in Example 8, the control group, and Comparative Example 2, with the three images on the left, center, and right corresponding to the control group, Comparative Example 2, and Example 8, respectively; (b) Temperature change curves of the thermal interface materials in Example 8, the control group, and Comparative Example 2, respectively, during the on-machine test. Detailed Implementation

[0040] Example 1

[0041] A method for preparing a graphene composite phase change thermal interface material includes the following steps:

[0042] S1: Provide a graphene oxide dispersion (graphene oxide content 4wt%, solvent is water, graphene oxide lateral dimension is 14.1μm), and use a centrifugal roller coating process (spray the graphene oxide dispersion into a centrifugally rotating drying track cavity through a syringe, use polyethylene terephthalate film as substrate, dry each film layer in an 80℃ heating chamber for 1 min, repeat this process until the target thickness is reached) to form multiple layers of graphene oxide unit layers on the substrate, and obtain a graphene oxide film (thickness 300μm) after drying.

[0043] S2: Take the graphene oxide film (6 pieces) and place it between two graphite plates (muffle furnace) for gradient thermal reduction treatment (initial pressure 50 kPa, at 0.5℃·min). -1 The heating rate was from room temperature to 150°C, and then at a rate of 1°C·min. -1The film is heated to 350°C at a rate that allows it to expand controllably in the out-of-plane direction, forming a reduced graphene oxide film with a micro-nano cavity structure; the volume expansion coefficient of the reduced graphene oxide film is 20.

[0044] S3: Graphitize the reduced graphene oxide film (under argon protection, using a 300kW, 1kHz medium-frequency graphitization furnace at 5℃·min). -1 (Heating rate to 3050℃), such as Figure 3 As shown in (e), a density of 0.07 g·cm³ was obtained. -3 Graphene micro / nano cavity films;

[0045] S4: A graphene composite phase change thermal interface material was obtained by vacuum impregnation (immersing a graphene micro-nano cavity film into molten phase change material Tris at a pressure of 35 mbar) (filling temperature 178℃, filling time 8h).

[0046] Example 2

[0047] The specific implementation method is the same as in Example 1; the difference is that in S2, the number of graphene oxide films is 24, and the volume expansion coefficient of the reduced graphene oxide film is 5; in S3, as... Figure 3 As shown in (a), a density of 0.19 g·cm³ was obtained. -3 Graphene micro-nano cavity films.

[0048] Example 3

[0049] The specific implementation method is the same as in Example 1; the difference is that in S2, the number of graphene oxide films is 16, and the volume expansion coefficient of the reduced graphene oxide film is 8; in S3, as... Figure 3 As shown in (b), a density of 0.17 g·cm³ was obtained. -3 Graphene micro-nano cavity films.

[0050] Example 4

[0051] The specific implementation method is the same as in Example 1; the difference is that in S2, the number of graphene oxide films is 12, and the volume expansion coefficient of the reduced graphene oxide film is 10; in S3, as... Figure 3 As shown in (c), a density of 0.12 g·cm³ was obtained. -3 Graphene micro-nano cavity films.

[0052] Example 5

[0053] The specific implementation method is the same as in Example 1; the difference is that in S2, the number of graphene oxide films is 8, and the volume expansion coefficient of the reduced graphene oxide film is 15; in S3, as... Figure 3As shown in (d), a density of 0.09 g·cm³ was obtained. -3 Graphene micro-nano cavity films.

[0054] Example 6

[0055] The specific implementation method is the same as in Example 1; the difference is that in S2, the number of graphene oxide films is 4, and the volume expansion coefficient of the reduced graphene oxide film is 30; in S3, as... Figure 3 As shown in (f), a density of 0.028 g·cm³ was obtained. -3 Graphene micro-nano cavity films.

[0056] Example 7

[0057] Micropores uniformly distributed along the diagonal direction were formed on the surface of the graphene micro-nano cavity film prepared in Example 3 by ultrashort laser pulses. By controlling the spot size and the number of holes, four through holes with a diameter of 50 μm were introduced in a 1 cm × 1 cm area.

[0058] Example 8

[0059] The specific implementation method is the same as in Example 7, except that four through holes with a diameter of 100 μm are introduced in a 1 cm × 1 cm area.

[0060] Example 9

[0061] The specific implementation method is the same as in Example 7, except that four through holes with a diameter of 200 μm are introduced in a 1 cm × 1 cm area.

[0062] Example 10

[0063] The specific implementation method is the same as in Example 7, except that eight through holes with a diameter of 50 μm are introduced in a 1 cm × 1 cm area.

[0064] Example 11

[0065] The specific implementation method is the same as in Example 7, except that eight through holes with a diameter of 100 μm are introduced in a 1 cm × 1 cm area.

[0066] Example 12

[0067] The specific implementation method is the same as in Example 7, except that eight through holes with a diameter of 200 μm are introduced in a 1 cm × 1 cm area.

[0068] Comparative Example 1

[0069] The specific implementation method is the same as in Example 1; the difference is that S1: a conventional scraper coating method is used (scraper gap 100μm, speed 5mm·s). -1 The graphene oxide film (thickness 300 μm) was prepared by drying at 75℃ for 6 h.

[0070] Comparative Example 2

[0071] Graphene film pad (brand name: OGFP).

[0072] Comparative Example 3

[0073] Silicone rubber pad (brand name: SRP).

[0074] Performance testing methods and data

[0075] 1. The thin film structure was characterized using scanning electron microscopy: such as... Figure 1 As shown, during centrifugal roll coating, the synergistic effect of centrifugal force and shear force ensures that the sub-μm flakes in the graphene oxide film are highly aligned and tightly packed. During thermal reduction, the decomposition of oxygen-containing groups in the graphene oxide film sheets leads to interlayer expansion, forming micro-nano voids. The sheets in the reduced graphene oxide film still maintain sub-μm size and quasi-parallel alignment (angle <10°). After graphitization, the graphene micro-nano cavity film retains the basic structure of the reduced graphene oxide film framework, but the sheets become wrinkled and spontaneously assemble into micro-nano cavities. The graphene sheets overlap through van der Waals forces to form continuous pore walls, which are bridged by graphene. In the horizontal direction, the continuous hexagonal channels form a honeycomb-like structure, creating a significant difference from the vertical cross-section. This structure maximizes in-plane thermal conductivity by reducing phonon scattering paths, while the continuous pore wall structure in the vertical direction provides additional phonon transmission paths.

[0076] 2. Characterization was performed using X-ray photoelectron spectroscopy. For example... Figure 2 As shown in (a), during the thermal reduction process, most of the oxygen-containing functional groups in the graphene oxide film are removed, leaving only a small amount of O elements in the reduced graphene oxide film, mainly existing in the form of carboxyl groups. Meanwhile, sp... 3 The proportion of hybrid carbon increased significantly. After graphitization treatment of reduced graphene oxide films, the oxygen-containing functional group peaks almost disappeared, and sp... 2 The further decrease in the intensity of the C peak indicates that the graphene micro-nano cavity film is composed of high-quality graphene sheets.

[0077] 3. Characterization was performed using Raman spectroscopy. For example... Figure 2 As shown in (b), graphene and its derivatives exhibit three characteristic peaks, namely the G peak (~1585 cm⁻¹). -1 D peak (~1350cm) -1 ) and 2D peak (~2700cm) -1 The intensity ratio of the D peak to the G peak (ID / IG) reflects the sp... 2 / sp 3The higher the carbon content and defect density, the smaller the ID / IG ratio, indicating a more complete graphene structure. In the initial stage of thermal reduction, some oxygen-containing functional groups in the graphene oxide film decompose, generating vacancies and increasing the ID / IG ratio from 0.94 to 1.02 (532nm laser excitation). This indicates that a significant number of defects still exist in the reduced graphene oxide film. However, after graphitization, the ID / IG ratio drops sharply to 0.09, confirming the high-quality characteristics of the graphene micro / nano cavity film.

[0078] 4. Characterization was performed using X-ray diffraction. For example... Figure 2 As shown in (c), the graphene oxide in the graphene oxide film has low crystallinity, and its diffraction peak corresponding to the (002) crystal plane of graphene is broad and has extremely low intensity. After thermal reduction and graphitization, the crystallinity of the graphene micro / nano cavity film is significantly improved, and the full width at half maximum (FWHM) of its (002) crystal plane diffraction peak is significantly smaller than that of the graphene oxide film and the reduced graphene oxide film. In addition, almost no impurity peaks are visible in the graphene micro / nano cavity film. Raman spectroscopy and X-ray diffraction results together show that the graphitization process significantly improves the crystallinity of graphene.

[0079] 5. Comparison of the reduced graphene oxide film structures in Example 1 and Comparative Example 1, such as... Figure 4 The results showed that the thickness of the unit layer of the centrifugally rolled film was uniform after thermal reduction, while the thickness of the blade-coated film was compressed and aggregated due to uneven interlayer stress distribution.

[0080] 6. Characterization of graphene composite phase change thermal interface materials: such as Figure 5 As shown, the graphene micro / nano cavity framework remained intact during the filling process, with a density of only 0.19 g / cm³. 3 Some samples showed elongated voids. In the composite materials of the other examples, the Tris matrix was uniformly wrapped by a graphene network, and the porous framework structure had high integrity.

[0081] 7. Using a laser flash apparatus (Netzsch LFA467 HyperFlash), the in-plane (k) parameters of Examples 1-6 were tested using both the laser flash method (ASTM E 1461) and the steady-state method (ASTM D 5470). / / ) and out-of-plane (k) ⊥ Thermal conductivity, density ρ ), specific heat capacity ( C p ), thermal diffusivity (in-plane) α / / , out-of-plane α ⊥ ), interface thermal resistance ( ), enthalpy value ( ) and its normalized value and comprehensive performance factor ( The in-plane and out-of-plane thermal conductivity of the graphene composite phase change thermal interface material was tested. For in-plane testing, a Φ=25.4mm mold was used to match the laser spot size, while for out-of-plane testing, a Φ=12.5mm mold was used to reduce contact thermal resistance. All samples were coated with a 10μm thick graphite layer before testing to ensure uniform emissivity and signal-to-noise ratio. The test results are shown in Tables 1 and 2.

[0082] 8. Using a laser flash apparatus (Netzsch LFA467 HyperFlash), the out-of-plane (k) parameters of Examples 7-12 were tested using both the laser flash method (ASTM E 1461) and the steady-state method (ASTM D 5470). ⊥ Thermal conductivity, density ρ ), specific heat capacity ( C p ), out-of-plane α ⊥ The thermal diffusivity and test results are shown in Table 3.

[0083] 9. Thermal Imaging Test: To verify the impact of laser-induced aperture creation on thermal management performance, the thermal management performance of the phase change materials in Examples 1 and 8 was tested using an infrared thermal imaging camera. The hot stage temperature was set to 160°C, and the samples were loaded onto ultrathin copper sheets. Before the formal test, all samples underwent a phase change cycle and were subjected to a certain pressure to eliminate thermal history and residual stress. The results are as follows: Figure 6 As shown, both exhibit a plateau period when their temperature rises from room temperature to near the phase transition point, which corresponds to their phase transition process. A longer phase transition plateau indicates stronger resistance to transient thermal shock. Infrared thermal imaging observations of the material surface heating process show that the temperature change time of Example 8 is significantly longer than that of Example 3 without pore formation. The temperature change curves also corroborate this phenomenon. Example 8 exhibits a wider phase transition plateau, corresponding to its superior resistance to transient thermal shock.

[0084] 10. Using a laser flash apparatus (Netzsch LFA467 HyperFlash), the out-of-plane (k) values ​​of Comparative Examples 2 and 3 were tested using both the laser flash method (ASTM E 1461) and the steady-state method (ASTM D 5470). ⊥ Thermal conductivity and interfacial thermal resistance The test results are shown in Table 4. The interfacial thermal resistances (Rtotal) of OGFP and SRP are 0.89 and 2.49, respectively, which are significantly higher than those of the thermal interface material of this invention. Because the graphene in OGFP is ordered along its in-plane orientation, it has only a few interfacial contacts, resulting in a lower out-of-plane thermal conductivity. Similarly, the low intrinsic thermal conductivity of the silicone grease in SRP also makes its out-of-plane thermal conductivity significantly lower than the other two TIMs. Therefore, the thermal interface material of this invention has significant advantages in both interfacial thermal resistance and out-of-plane thermal conductivity.

[0085] 11. Thermal Performance Testing: To evaluate the interfacial heat transfer performance of the thermal interface material of this invention under actual working conditions, a thermal management test platform was built based on an AMD Ryzen R5 5500 GT (65W) chip. Three experimental groups were set up: a blank group (no TIM), a control group (SRP TIM, corresponding to ratio 3), and an experimental group (Example 8). All TIMs were cut to 9mm × 9mm × 1mm and subjected to a packaging pressure of 0.15MPa. Figure 7 As shown in (a), the surface temperature of the chip in the experimental group was reduced by 14.4°C and 5.5°C compared with the blank group and the control group, respectively, which confirms the interface thermal resistance optimization effect of the thermal interface material of the present invention.

[0086] Table 1

[0087]

[0088] Table 2

[0089]

[0090] Table 3

[0091]

[0092] Table 4

[0093]

Claims

1. A method for preparing a graphene composite phase change thermal interface material, characterized in that, The process includes the following steps: preparing a graphene oxide dispersion, forming multiple graphene oxide unit layers on a substrate using centrifugal roller coating and layer-by-layer drying processes to obtain a graphene oxide film; placing the graphene oxide film in a confined space and performing gradient thermal reduction treatment to cause the film to expand controllably in the out-of-plane direction, forming a reduced graphene oxide film with a micro-nano cavity structure. The reduced graphene oxide film is graphitized to obtain a graphene micro-nano cavity film; molten phase change material is filled into the micro-nano cavity structure of the graphene micro-nano cavity film by vacuum impregnation to obtain a graphene composite phase change thermal interface material. The centrifugal roller coating and layer-by-layer drying process is as follows: the graphene oxide dispersion is sprayed into the centrifugally rotating drying track cavity through a syringe to form a thin film; after each film is dried in the heating chamber, this process is repeated until the target thickness is reached; The volume expansion coefficient of the reduced graphene oxide film is 3-20; the expansion coefficient is the volume after expansion / the initial volume. The gradient thermal reduction process includes: heating the graphene oxide film to 120-190℃ at a heating rate of 0.2-0.9℃ / min under a pressure of 30-80 kPa, and then heating it to 300-390℃ at a heating rate of 0.8-2℃ / min.

2. The production method according to claim 1, characterized by, The graphitization process includes heating the reduced graphene oxide film to 2900-3100°C at a heating rate of 3-10°C / min.

3. The production method according to claim 1 or 2, characterized by, The thickness of the graphene oxide film is 1-10 μm.

4. The production method according to claim 3, characterized by, The density of the graphene micro-nano cavity film is 0.02-0.3 g / cm 3 .

5. The preparation method according to claim 3, characterized in that, The filling temperature is 170-190℃, and the filling time is 6-10 hours.

6. The method of claim 1, wherein, The phase change material includes polyols.

7. The preparation method according to claim 1, characterized in that, At least one through hole is formed on the surface of the graphene composite phase change thermal interface material.

8. The preparation method according to claim 7, characterized in that, The diameter of the through holes is 50-200μm, and the number is 2-10.

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