Graphene heat dissipation film and its preparation method

Abstract

This application relates to a graphene heat dissipation film and its preparation method. The preparation method of the graphene heat dissipation film includes the following steps: preparing a mixed slurry containing graphene oxide and a defect repair agent; performing a film-forming treatment on the mixed slurry to obtain a first film; performing carbonization, graphitization, and calendering treatment on the first film to obtain a second film; forming a radiation heat dissipation layer on the second film to obtain the graphene heat dissipation film; wherein, the graphene oxide includes at least two of first graphene oxide, second graphene oxide, and third graphene oxide; the lateral dimension of the first graphene oxide is larger than the lateral dimension of the second graphene oxide; the lateral dimension of the second graphene oxide is larger than the lateral dimension of the third graphene oxide; the defect repair agent includes at least one of glucose, citric acid, citrate, and vitamin C. This graphene heat dissipation film has the advantages of low structural defects, high production yield, diverse heat dissipation mechanisms, and excellent heat dissipation performance.

Description

Technical Field

[0001] This application relates to the field of thermal management technology, and in particular to a graphene heat dissipation film and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, big data, and artificial intelligence technologies, electronic products are evolving towards miniaturization, thinner and lighter designs, multi-functionality, and higher performance. This has led to more compact internal structures, higher component integration, and continuously increasing power consumption and heat generation. If excessive heat cannot be removed in time, it will severely impact the overall performance and lifespan of the equipment. Research shows that over 55% of electronic devices fail due to overheating. When the operating temperature of components reaches 70℃~80℃, for every 1℃ increase, the reliability of the equipment decreases by 5%; an increase of 10℃~20℃ increases the failure rate by 100%. Therefore, an efficient thermal management system is urgently needed to ensure the operating efficiency, safety, reliability, stability, and durability of electronic equipment.

[0003] The most effective way to solve heat dissipation problems is to use materials with superior thermal conductivity to promptly transfer the heat generated by internal components of electronic devices to external heat sinks, thereby reducing their operating temperature. Graphene heat dissipation films, as an emerging heat dissipation material, possess excellent properties such as high thermal conductivity, high heat flux, good flexibility, light weight, and low coefficient of thermal expansion. They can be used as heat sinks in electronic components to evenly distribute the heat generated by heat sources. They have significant advantages in eliminating localized hot spots, smoothing temperature gradients, and changing the direction of heat flow, and have great potential for low-cost, large-scale industrial production, making them the most promising heat dissipation material in the field of thermal management. However, the poor heat dissipation effect of graphene heat dissipation films prepared by traditional methods limits their application in thermal management. Summary of the Invention

[0004] Therefore, it is necessary to provide a graphene heat dissipation film and its preparation method to solve the problem of poor heat dissipation effect of graphene heat dissipation films prepared by traditional methods.

[0005] The above-mentioned objective of this application is achieved through the following technical solution:

[0006] In a first aspect, this application provides a method for preparing a graphene heat dissipation film, comprising the following steps: preparing a mixed slurry containing graphene oxide and a defect repair agent;

[0007] The mixed slurry is subjected to a film-forming treatment to obtain a first thin film;

[0008] The first film is subjected to carbonization, graphitization and calendering to obtain the second film;

[0009] A radiation heat dissipation layer is formed on the second thin film to obtain a graphene heat dissipation film;

[0010] The graphene oxide includes at least two of the following: first graphene oxide, second graphene oxide, and third graphene oxide.

[0011] The lateral dimension of the first graphene oxide is larger than that of the second graphene oxide;

[0012] The lateral dimension of the second graphene oxide is larger than that of the third graphene oxide;

[0013] The defect repair agent includes at least one of glucose, citric acid, citrate, and vitamin C.

[0014] In one embodiment, the lateral dimension of the first graphene oxide is 0.1 μm to 3.0 μm;

[0015] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0016] The lateral dimension of the third graphene oxide is less than 50 nm.

[0017] In one embodiment, the mass ratio of the first graphene oxide, the second graphene oxide, and the third graphene oxide is 1:(0.1~1):(0~1).

[0018] In one embodiment, the thickness of the graphene oxide is 0.3 nm to 4 nm.

[0019] In one embodiment, the atomic percentage ratio of carbon to oxygen in the graphene oxide is 1.6 to 3.0.

[0020] In one embodiment, the mass ratio of the graphene oxide to the defect repair agent is 10:(1~5).

[0021] In one embodiment, the carbonization treatment is carried out at a temperature of 600°C to 1000°C for a time of 2 hours to 5 hours.

[0022] The graphitization process is carried out under a protective atmosphere at a temperature of 1500℃~2500℃ for 2h~30h.

[0023] In one embodiment, the thickness of the second film is 10 μm to 80 μm, and the density is 1.5 g / cm³. 3 ~2.2g / cm 3 .

[0024] In one embodiment, forming a radiative heat dissipation layer on the second film includes the following steps: spraying a radiative heat dissipation coating onto the second film to form the radiative heat dissipation layer.

[0025] In one embodiment, the radiative heat dissipation coating comprises one or more of a polyvinylidene fluoride-hexafluoropropylene solution, a first mixture containing inorganic carbon materials, and a second mixture containing nano-oxides.

[0026] In a second aspect, this application provides a graphene heat dissipation film, which is prepared using the graphene heat dissipation film preparation method described above.

[0027] This application has at least the following beneficial effects:

[0028] This application utilizes a blend of graphene oxides with varying lateral dimensions to fill the voids in larger graphene oxides with smaller pores and wrinkles, thereby producing a first film with fewer intrinsic defects. A defect repair agent, selected from organic compounds such as glucose, citric acid, citrate, and vitamin C, is added to the mixed slurry. This agent completely decomposes into carbon during carbonization, repairing structural defects in the first film and improving production yield and thermal conductivity, while reducing energy consumption and manufacturing costs. Simultaneously, a radiative heat dissipation layer is formed on top of the second film, not only repairing the coating but also matching thermal conduction and radiation during operation for synergistic heat dissipation. Therefore, the graphene heat dissipation film obtained in this application possesses advantages such as low structural defects, high production yield, diverse heat dissipation mechanisms, and excellent heat dissipation performance, showing great promise for applications in the field of thermal management. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of a method for preparing a graphene heat dissipation film in one embodiment.

[0031] Figure 2 The image shows the AFM microstructure of the first graphene oxide in Example 1.

[0032] Figure 3 This is an AFM thickness diagram of the first graphene oxide in Example 1;

[0033] Figure 4This is an AFM microstructure image of the second graphene oxide from Example 1;

[0034] Figure 5 This is a SEM image of the front side of the second film prepared in Example 1;

[0035] Figure 6 This is an SEM image of the cross-section of the second thin film obtained in Example 1. Detailed Implementation

[0036] To facilitate understanding of this application, the following detailed description is provided in conjunction with specific embodiments. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0038] In this application, "and / or" means any and all combinations of one or more of the related listed items. "At least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two, three, etc., unless otherwise expressly and specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0039] When a numerical range is disclosed in this application, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed in this application should be understood to include any and all subranges to which they are included.

[0040] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0041] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0042] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0043] In this application, room temperature refers to indoor temperature, normal temperature, or general temperature. Generally, room temperature can be any of the following temperature ranges: 23℃±2℃, 25℃±5℃, or 20℃±5℃.

[0044] the term

[0045] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0046] Dimensions of graphene oxide: Graphene oxide is a two-dimensional material. Its dimensions in the planar direction are usually called its lateral dimensions, and its dimensions in the direction perpendicular to the planar direction are called its thickness.

[0047] Currently, heat sinks in electronic devices generally use metal thermal conductive materials such as copper, silver, and aluminum. These materials have disadvantages such as poor mechanical properties and high density. On the one hand, they increase the overall weight of the heat dissipation system, which is not conducive to the development of lightweight and miniaturized devices. On the other hand, the difficulty in stretching and bending metals also limits their application in complex heat dissipation components, such as foldable smartphones, laptops, and spacecraft.

[0048] Carbon-based thin film materials possess advantages such as low density, high thermal conductivity, low coefficient of thermal expansion, and good chemical stability, making them fast and efficient heat transfer materials. They are particularly suitable for heat dissipation in small-space, high-heat-flux-density components, playing a crucial role in consumer electronics, communication equipment, power batteries, and aerospace. Common carbon-based thin film materials include diamond films, graphite films, and graphene films. Among these, diamond films are characterized by high hardness and brittleness, making them difficult to process and resulting in high production costs. Graphite films are made from polyimide (PI) films, which are also challenging to produce. Graphene is currently the two-dimensional material with the highest known thermal conductivity. Graphene heat dissipation films, as an emerging heat dissipation material, combine high thermal conductivity, high heat flux, good flexibility, light weight, and a low coefficient of thermal expansion. They can be used as heat sinks in electronic components, uniformly dispersing heat generated by heat sources. They offer significant advantages in eliminating localized hot spots, smoothing temperature gradients, and changing the direction of heat flow, possessing great potential for low-cost, large-scale industrial production, making them the most promising heat dissipation material in the field of thermal management.

[0049] A method for preparing a graphene heat dissipation film has been reported: Artificial graphite powder, graphene oxide slurry, and a peeling agent are mixed uniformly and then peeled to obtain a mixed slurry. After degassing, the mixed slurry is coated onto a substrate, followed by drying, peeling, carbonization, graphitization, and calendering processes to obtain the graphene heat dissipation film. This method can effectively improve the overall thermal conductivity and uniformity of the graphene heat dissipation film. However, structural defects are easily generated during the preparation process, which reduces the yield and thermal conductivity of the graphene heat dissipation film, and increases energy consumption and preparation costs.

[0050] This is because the main raw material of graphene heat dissipation films is graphene oxide powder. It is not a material with a single layer number, single lateral dimension, or single thickness. In fact, it is a mixture of graphene oxide with different lateral dimensions and thicknesses, resulting in a wide range of thicknesses, lateral dimensions, and thickness distributions, significant structural differences, and relatively poor uniformity. Therefore, structural defects are easily generated during processes such as dispersion, coating, carbonization, and graphitization, thus affecting the performance improvement of the graphene heat dissipation film. Furthermore, traditional graphene heat dissipation films, in their design and production, often focus on the lateral (i.e., in-plane) thermal conductivity or uniform heat dissipation capabilities of the graphene thermal conductive film, neglecting its heat dissipation and radiative heat dissipation capabilities in the thickness direction. This leads to a single heat dissipation mechanism in the graphene heat dissipation film, resulting in a situation where the lateral thermal conductivity of the graphene heat dissipation film is high, but the heat dissipation effect is not ideal.

[0051] Based on this, this application provides a graphene heat dissipation film and its preparation method to solve the problem of poor heat dissipation effect of graphene heat dissipation films prepared by traditional methods.

[0052] Please see Figure 1This is a schematic flowchart illustrating the preparation method of a graphene heat dissipation film in one embodiment. Figure 1 As shown, the preparation method of graphene heat dissipation film includes the following steps:

[0053] S100: Preparation of a mixed slurry containing graphene oxide and a defect repair agent;

[0054] S200: The mixed slurry is subjected to film-forming treatment to obtain the first thin film;

[0055] S300: The first film is subjected to carbonization, graphitization and calendering to obtain the second film;

[0056] S400: A radiation heat dissipation layer is formed on the second thin film to obtain a graphene heat dissipation film;

[0057] Among them, graphene oxide includes at least two of graphene oxide, graphene oxide, and graphene oxide.

[0058] The lateral dimension of the first graphene oxide is larger than that of the second graphene oxide;

[0059] The lateral dimension of the second graphene oxide is larger than that of the third graphene oxide;

[0060] Defect repair agents include at least one of glucose, citric acid, citrate, and vitamin C.

[0061] This application utilizes a blend of graphene oxides with varying lateral dimensions to fill the voids in larger graphene oxides with smaller pores and wrinkles, thereby producing a first film with fewer intrinsic defects. A defect repair agent, selected from organic compounds such as glucose, citric acid, citrate, and vitamin C, is added to the mixed slurry. This agent completely decomposes into carbon during carbonization, repairing structural defects in the first film and improving production yield and thermal conductivity, while reducing energy consumption and manufacturing costs. Simultaneously, a radiative heat dissipation layer is formed on top of the second film, not only repairing the coating but also matching thermal conduction and radiation during operation for synergistic heat dissipation. Therefore, the graphene heat dissipation film obtained in this application possesses advantages such as low structural defects, high production yield, diverse heat dissipation mechanisms, and excellent heat dissipation performance, showing great promise for applications in the field of thermal management.

[0062] The preparation method of graphene heat dissipation film is described in detail below using a step-by-step approach.

[0063] S100: Prepare a mixed slurry containing graphene oxide and a defect repair agent.

[0064] This application selects graphene oxide (GO) as the main raw material for graphene heat dissipation film. GO is easy to dissolve and modify, has good compatibility with polymers, and the oxygen-containing functional groups such as -COOH and -OH on GO can undergo cross-linking to form a graphene oxide film (i.e., the first film). The preparation process is relatively simple and the cost is low.

[0065] Optionally, the lateral dimensions of the first graphene oxide are 0.1 μm to 3.0 μm;

[0066] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0067] The lateral dimensions of the third type of graphene oxide are less than 50 nm.

[0068] By optimizing the lateral dimensions of graphene oxide and reasonably limiting and combining the lateral dimensions of the three types of graphene oxide, the smaller graphene oxide has a better filling effect on the larger graphene oxide, thus obtaining a first film with fewer intrinsic defects.

[0069] As examples, the lateral dimensions of the first graphene oxide include, but are not limited to: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, or 3.0 μm. In some specific examples, the typical lateral dimension of the first graphene oxide is 0.35 μm.

[0070] As an example, the lateral dimensions of the second graphene oxide include, but are not limited to: 50nm, 55nm, 60nm, 65nm, 70nm, 75nm, 80nm, 85nm, 90nm, 95nm, or 100nm.

[0071] As an example, the lateral dimensions of the third graphene oxide include, but are not limited to: 1nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, or 50nm.

[0072] Optionally, the mass ratio of the first graphene oxide, the second graphene oxide, and the third graphene oxide is 1:(0.1~1):(0~1).

[0073] As an example, the mass ratio of the first graphene oxide to the second graphene oxide includes, but is not limited to: 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1; the mass ratio of the first graphene oxide to the third graphene oxide includes, but is not limited to: 1:0, 1:0.01, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, or 1:1.

[0074] Optionally, the thickness of the graphene oxide is 0.3nm to 4nm, including but not limited to: 0.3nm, 0.5nm, 0.8nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm or 4nm, and further optionally 0.8nm to 2nm.

[0075] In this application, the thickness of graphene oxide is controlled within the range of 0.3nm to 4nm, which can improve the uniformity of graphene oxide and make the filling effect between graphene oxides of different lateral dimensions better.

[0076] In this application, by controlling and compounding the thickness of graphene oxide, the structural differences of graphene oxide can be further reduced, and the filling effect between graphene oxides of different lateral dimensions can be improved, resulting in fewer structural defects and higher internal density in the first film.

[0077] Optionally, the ratio of the atomic percentages of carbon and oxygen in graphene oxide (C / O) is 1.6 to 3.0, including but not limited to: 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.

[0078] In this application, by controlling the ratio of the atomic percentages of carbon and oxygen in graphene oxide, it is possible to ensure that it has sufficient oxygen-containing functional groups for cross-linking reactions, thereby obtaining a first film with better density.

[0079] Optionally, the mass ratio of graphene oxide to defect repair agent is 10:(1~5), including but not limited to: 10:1, 10:1.5, 10:2, 10:2.5, 10:3, 10:3.5, 10:4, 10:4.5 or 10:5.

[0080] Understandably, the defect repair agents in this application are all small molecules, and their molecular structures do not contain nitrogen or other heteroatoms. They can be removed under mild conditions after defect repair, and the process is simple. The defect repair agent can be selected from any one of glucose, citric acid, citrate, and vitamin C, or a combination of at least two of glucose, citric acid, citrate, and vitamin C, including but not limited to: combinations of glucose and citric acid, glucose and citrate, glucose and vitamin C, citric acid and citrate, citric acid and vitamin C, glucose, citric acid and citrate, glucose, citric acid and vitamin C, glucose, citrate, and vitamin C, citric acid, citrate, and vitamin C. The citrate can be sodium citrate or potassium citrate. Further optionally, the defect repair agent is glucose.

[0081] Optionally, the mixed slurry may also include additives such as dispersants and defoamers to improve dispersibility and uniformity.

[0082] Optionally, the solvent in the mixed slurry includes one or more of water, methanol, ethanol, and isopropanol, and more preferably water. The water can be tap water, industrial water, distilled water, reverse osmosis water, deionized water, pure water, and ultrapure water, and more preferably deionized water or pure water.

[0083] Optionally, the preparation method of the mixed slurry includes the following steps: mixing graphene oxide and a solvent, performing a first mechanical stirring and a first ultrasonic dispersion to obtain a graphene oxide slurry; mixing the graphene oxide slurry and a defect repair agent, performing a second mechanical stirring and a second ultrasonic dispersion to obtain the mixed slurry. The mass fraction of graphene oxide in the graphene oxide slurry is 0.1% to 8%, including but not limited to: 0.1%, 0.2%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, or 8%. The rotation speeds of the first and second mechanical stirring are each independently 1000 rpm to 2000 rpm, including but not limited to: 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, or 2000 rpm; the stirring times of the first and second mechanical stirring are each independently 1 h to 3 h, including but not limited to: 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h, or 3 h; the ultrasonic dispersion times of the first and second ultrasonic dispersion are each independently 0.5 h to 2 h, including but not limited to: 0.5 h, 0.8 h, 1 h, 1.2 h, 1.5 h, 1.8 h, or 2 h.

[0084] S200: The mixed slurry is subjected to film-forming treatment to obtain the first film.

[0085] Optionally, the film-forming process includes the following steps: forming a wet film from the mixed slurry using a coating or filtration method, and removing the solvent from the wet film by a drying process.

[0086] In the mixed slurry, there is a certain π-π conjugation between graphene oxides of different transverse sizes, which allows small-sized graphene oxides to be adsorbed into the gaps of large-sized graphene oxides and promotes filling and assembly during the film formation process, thereby forming a first film with few intrinsic defects and high internal density.

[0087] As an example, the coating method includes one or more of the following: blade coating, spin coating, brush coating, spray coating, and slot coating, and may further be blade coating. The filtration method includes one or more of the following: ordinary filtration, vacuum filtration, and pressure filtration, and may further be vacuum filtration.

[0088] Optionally, the drying temperature is 50℃~95℃, and the time is 2h~5h. As an example, the drying temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, or 95℃; and the drying time can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.

[0089] In this application, drying at 50℃~95℃ can evaporate solvents such as water or ethanol in the wet film and cause oxygen-containing functional groups such as -COOH and -OH on the surface of graphene oxide to undergo cross-linking reactions to form a continuous and dense first film.

[0090] S300: The first film is subjected to carbonization, graphitization and calendering to obtain the second film.

[0091] Optionally, the carbonization treatment temperature is 600℃~1000℃, and the time is 2h~5h. As an example, the carbonization treatment temperature can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, or 1000℃; the carbonization treatment time can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.

[0092] This application employs a carbonization process at 600℃~1000℃ to remove oxygen-containing functional groups such as -COOH and -OH from graphene oxide, while simultaneously decomposing defect repair agents like glucose into carbon. This results in the formation of an amorphous carbon layer on the film surface, significantly improving both electrical and thermal conductivity while increasing the carbon content. The removal of the defect repair agent is gentle and residue-free, improving product yield and thermal conductivity while reducing energy consumption and manufacturing costs.

[0093] Optionally, the graphitization treatment is carried out under a protective atmosphere at a temperature of 1500℃ to 2500℃ for a time of 2h to 30h. As an example, the protective atmosphere includes one or more of nitrogen, helium, argon, neon, and xenon; the graphitization temperature can be 1500℃, 1600℃, 1700℃, 1800℃, 1900℃, 2000℃, 2100℃, 2200℃, 2300℃, 2400℃, or 2500℃; and the graphitization time can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, or 30h.

[0094] This application involves graphitization treatment at 1500℃~2500℃, which can transform carbonized graphene oxide into a graphite structure, thereby reducing the interlayer spacing of graphene oxide and making the carbon atoms more orderly arranged, resulting in higher crystallinity and better electrical and thermal conductivity.

[0095] Optionally, the thickness of the second film is 10 μm to 80 μm, and the density is 1.8 g / cm³. 3 ~2.2g / cm 3 As an example, the thickness of the second film can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm, and the density can be 1.8 g / cm³. 3 1.9g / cm 3 2g / cm 3 2.1g / cm 3 Or 2.2g / cm 3 .

[0096] Alternatively, the calendering process may be carried out using a roll press or a calender.

[0097] S400: A radiation heat dissipation layer is formed on the second thin film to obtain a graphene heat dissipation film;

[0098] Optionally, forming a radiative heat dissipation layer on the second film includes the following steps: spraying a radiative heat dissipation coating onto the second film to form a radiative heat dissipation layer.

[0099] Understandably, the second film has a first surface and a second surface that are relatively parallel. The first surface is close to the heat source and can be attached to the heat source, while the second surface is away from the heat source. The radiative heat dissipation layer is located on the second surface of the second film. During the operation of the graphene heat dissipation film, the synergistic heat dissipation effect is achieved through the matching of the thermal conduction of the second film and the thermal radiation of the radiative heat dissipation layer.

[0100] This application uses a high-emissivity radiative heat dissipation coating sprayed onto the second film.

[0101] Optionally, the radiative heat dissipation coating includes one or more of the following: a polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP) solution, a first mixture containing inorganic carbon materials, and a second mixture containing nano-oxides.

[0102] Optionally, the mass fraction of PVDF-HFP in the PVDF-HFP solution is 25% to 50%. PVDF-HFP refers to a copolymer of vinylidene fluoride and hexafluoropropylene. The preparation method of the PVDF-HFP solution is as follows: PVDF-HFP is dissolved in acetone, and water is added to obtain the PVDF-HFP solution.

[0103] Optionally, the inorganic carbon material includes one or more of graphene, carbon nanotubes, graphene oxide, carbon fibers, and fullerenes, and is further selected as graphene and carbon nanotubes; the mass fraction of the inorganic carbon material in the first mixture is 0.1% to 1%; the solvent of the first mixture includes one or more of water, methanol, ethanol, and isopropanol.

[0104] Optionally, the nano-oxide includes one or more of nano-silica, nano-titanium dioxide, nano-zinc dioxide, and nano-magnesium oxide, and is further optionally nano-silica; the particle size of the nano-oxide is 10nm~1000nm, including but not limited to: 10nm, 20nm, 50nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, or 1000nm; the mass fraction of the nano-oxide in the second mixture is 30%~40%; the solvent of the second mixture includes one or more of water, methanol, ethanol, and isopropanol.

[0105] Optionally, the thickness of the radiative heat dissipation layer is 0.1 μm to 1 μm. As an example, the thickness of the radiative heat dissipation layer can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm.

[0106] In a second aspect, this application provides a graphene heat dissipation film, which is prepared using the graphene heat dissipation film preparation method described above.

[0107] Optionally, the thickness of the graphene heat dissipation film is 10 μm to 80 μm. As an example, the thickness of the graphene heat dissipation film can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm.

[0108] Optionally, the density of the graphene heat dissipation film is 1.5 g / cm³. 3 ~2.2g / cm 3 As an example, the density of a graphene heat dissipation film can be 1.5 g / cm³. 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 1.9g / cm 3 2g / cm 3 2.1g / cm 3 Or 2.2g / cm 3 .

[0109] Optionally, the graphene heat dissipation film has a lateral thermal diffusivity of 550 mm. 2 / s~1080mm 2 / s. As an example, the lateral thermal diffusivity of a graphene heat dissipation film can be 550 mm². 2 / s, 600mm 2 / s, 700mm 2 / s, 800mm 2 / s, 900mm 2 / s, 1000mm 2 / s or 1080mm 2 / s.

[0110] Optionally, the thermal conductivity of the graphene heat dissipation film is ≥1400 W / (m·K). As an example, the thermal conductivity of the graphene heat dissipation film can be 1400 W / (m·K), 1450 W / (m·K), 1500 W / (m·K), 1550 W / (m·K), 1600 W / (m·K), 1650 W / (m·K), or 1700 W / (m·K).

[0111] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0112] Example 1

[0113] Please refer to Table 1. The preparation method of the graphene heat dissipation film in this embodiment is as follows:

[0114] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain graphene oxide slurry; add defect repair agent to graphene oxide slurry, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain mixed slurry.

[0115] Among them, the graphene oxide is selected from the first graphene and the second graphene in a mass ratio of 1:0.1.

[0116] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0117] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0118] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0119] The defect repair agent is glucose, and the mass ratio of graphene oxide to the defect repair agent is 10:2.

[0120] (2) The mixed slurry is uniformly coated to form a wet film using a coating machine, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0121] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film.

[0122] (4) The second film has a first surface and a second surface that are parallel to each other, with the second surface facing away from the heat source; a radiation heat dissipation coating is sprayed onto the second surface and dried to form a radiation heat dissipation layer with a thickness of 0.5 μm, thereby obtaining a graphene heat dissipation film.

[0123] The radiative heat dissipation coating uses PVDF-HFP solution.

[0124] Example 2

[0125] This embodiment is basically the same as embodiment 1, except that in step (4), the radiation heat dissipation coating is a first mixture containing inorganic carbon materials, including graphene and carbon nanotubes, the solvent of the first mixture is ethanol, and the thickness of the radiation heat dissipation layer obtained by spraying is 0.5 μm.

[0126] Example 3

[0127] This embodiment is basically the same as embodiment 1, except that: in step (4), the radiation heat dissipation coating is a second mixture containing nano-oxides, the nano-oxides are nano-silica with a particle size of 50nm, the solvent of the second mixture is water, and the thickness of the radiation heat dissipation layer obtained by spraying is 1μm.

[0128] Example 4

[0129] This embodiment is basically the same as embodiment 1, except that in step (1), the mass ratio of graphene oxide to glucose, the defect repair agent, is 10:1.

[0130] Example 5

[0131] This embodiment is basically the same as embodiment 1, except that in step (1), the mass ratio of graphene oxide to glucose, the defect repair agent, is 10:5.

[0132] Example 6

[0133] This embodiment is basically the same as embodiment 1, except that in step (1), citric acid is selected as the defect repair agent, and the mass ratio of graphene oxide to citric acid is 10:2.

[0134] Example 7

[0135] This embodiment is basically the same as that of embodiment 1, except that in step (1), the graphene oxide is selected from the first graphene and the third graphene in a mass ratio of 1:0.1.

[0136] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0137] The lateral dimensions of the third type of graphene oxide are less than 50 nm;

[0138] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0139] Example 8

[0140] This embodiment is basically the same as embodiment 1, except that in step (1), the graphene oxide is selected from the first graphene, the second graphene and the third graphene in a mass ratio of 1:0.1:0.1.

[0141] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0142] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0143] The lateral dimensions of the third type of graphene oxide are less than 50 nm;

[0144] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0145] Example 9

[0146] This embodiment is basically the same as that of embodiment 1, except that in step (1), the graphene oxide is selected from the fourth graphene and the fifth graphene in a mass ratio of 1:0.1.

[0147] The lateral dimensions of the fourth type of graphene oxide are 100 μm to 150 μm;

[0148] The lateral dimensions of graphene oxide (P5) range from 5 μm to 20 μm.

[0149] The thickness of graphene oxide is 5nm~15nm.

[0150] Comparative Example 1

[0151] The preparation method of the graphene heat dissipation film in this comparative example is as follows:

[0152] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and sonicate for 1 hour to obtain graphene oxide slurry.

[0153] Among them, the graphene oxide selected is first graphene, with a lateral dimension of 0.1μm~3.0μm and a thickness of 0.334nm~4nm;

[0154] (2) The graphene oxide slurry is uniformly coated with a coating machine to form a wet film, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0155] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film, which is the graphene heat dissipation film.

[0156] Comparative Example 2

[0157] The preparation method of the graphene heat dissipation film in this comparative example is as follows:

[0158] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain graphene oxide slurry; add defect repair agent to graphene oxide slurry, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain mixed slurry.

[0159] Among them, the graphene oxide selected is first graphene, with a lateral dimension of 0.1μm~3.0μm and a thickness of 0.334nm~4nm;

[0160] The defect repair agent is glucose, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0161] (2) The mixed slurry is uniformly coated to form a wet film using a coating machine, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0162] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film, which is the graphene heat dissipation film.

[0163] Comparative Example 3

[0164] The preparation method of the graphene heat dissipation film in this comparative example is as follows:

[0165] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain graphene oxide slurry; add defect repair agent to graphene oxide slurry, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain mixed slurry.

[0166] Among them, the graphene oxide selected is first graphene, with a lateral dimension of 0.1μm~3.0μm and a thickness of 0.334nm~4nm;

[0167] The defect repair agent is glucose, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0168] (2) The mixed slurry is uniformly coated to form a wet film using a coating machine, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0169] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film.

[0170] (4) The second film has a first surface and a second surface that are parallel to each other, with the second surface facing away from the heat source; a radiation heat dissipation coating is sprayed onto the second surface and dried to form a radiation heat dissipation layer with a thickness of 0.5 μm, thereby obtaining a graphene heat dissipation film.

[0171] The radiative heat dissipation coating uses PVDF-HFP solution.

[0172] Comparative Example 4

[0173] The preparation method of the graphene heat dissipation film in this comparative example is as follows:

[0174] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and sonicate for 1 hour to obtain graphene oxide slurry.

[0175] Among them, the graphene oxide is selected from the first graphene and the second graphene with a mass ratio of 1:0.2.

[0176] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0177] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0178] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0179] (2) The graphene oxide slurry is uniformly coated with a coating machine to form a wet film, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0180] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film, which is the graphene heat dissipation film.

[0181] Comparative Example 5

[0182] This comparative example is basically the same as comparative example 4, except that in step (1), the graphene oxide is selected from the first graphene and the third graphene in a mass ratio of 1:0.2.

[0183] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0184] The lateral dimensions of the third type of graphene oxide are less than 50 nm;

[0185] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0186] Comparative Example 6

[0187] This comparative example is basically the same as comparative example 4, except that in step (1), the graphene oxide is selected in a mass ratio of 1:0.2:0.2 for the first graphene, the second graphene and the third graphene.

[0188] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0189] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0190] The lateral dimensions of the third type of graphene oxide are less than 50 nm;

[0191] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0192] Comparative Example 7

[0193] The preparation method of the graphene heat dissipation film in this comparative example is as follows:

[0194] (1) Add graphene oxide to water, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain graphene oxide slurry; add defect repair agent to graphene oxide slurry, mechanically stir at 1500 rpm for 2 hours, and ultrasonically decompose for 1 hour to obtain mixed slurry.

[0195] Among them, the graphene oxide is selected from the first graphene and the second graphene with a mass ratio of 1:0.2.

[0196] The lateral dimensions of the first type of graphene oxide are 0.1 μm to 3.0 μm;

[0197] The lateral dimensions of the second graphene oxide are 50 nm to 100 nm.

[0198] The thickness of graphene oxide ranges from 0.334 nm to 4 nm.

[0199] The defect repair agent is glucose, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0200] (2) The mixed slurry is uniformly coated to form a wet film using a coating machine, and then dried at 70°C to evaporate the solvent, thus obtaining the first film.

[0201] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then it is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then it is calendered using a calender to obtain the second film, which is the graphene heat dissipation film.

[0202] Comparative Example 8

[0203] This comparative example is basically the same as comparative example 7, except that in step (1), the mass ratio of graphene oxide to glucose, the defect repair agent, is 10:2.

[0204] Comparative Example 9

[0205] This comparative example is basically the same as comparative example 7, except that in step (1), the mass ratio of graphene oxide to glucose, the defect repair agent, is 10:5.

[0206] Test case

[0207] 1. Morphological characterization of graphene oxide: The microstructure and thickness of graphene oxide were observed using a Dimension Icon atomic force microscope (AFM) manufactured by Bruker, Germany. The results are shown in the figure. Figures 2-4 .

[0208] Figure 2 This is an AFM microstructure image of the first graphene oxide from Example 1. Figure 3 The image shows the AFM thickness of the first graphene oxide in Example 1. It can be seen that the lateral dimensions of the first graphene oxide are 0.35 μm to 3.0 μm, with a typical value of 0.35 μm, and the thickness is 0.88 nm to 1.98 nm. Figure 4 The image shows the AFM microstructure of the second graphene oxide in Example 1. It can be seen that the lateral size of the second graphene oxide is between 50 nm and 100 nm, and the thickness is between 1 nm and 2 nm.

[0209] 2. Morphological characterization of the second thin film: The microstructure of the graphene heat dissipation film was observed using a Hitachi SU-8100 scanning electron microscope (SEM). The results are shown in the figure. Figures 5-6 .

[0210] Figure 5 This is a SEM image of the front side of the second film prepared in Example 1. Figure 6 The image shows a SEM image of the cross-section of the second film prepared in Example 1. It can be seen that the surface of the second film is highly smooth, with very few structural defects, and the cross-section exhibits a layered structure.

[0211] 3. Performance testing of graphene heat dissipation film:

[0212] (1) Thermal conductivity test: The density of the sample was calculated by mass-volume method; the specific heat capacity Cp of the sample at room temperature (25℃) was tested by differential scanning calorimetry (DSC) with a temperature range of -5℃ to 55℃ and a heating and cooling rate of 20℃ / min; the thermal conductivity of the sample at room temperature (25℃) was tested by laser scintillation method using a DXF-200 laser thermal conductivity meter manufactured by TA in the United States; the graphene heat dissipation film was cut into circular pieces with a diameter of 25.4mm and then placed in the in-plane mold of the thermal conductivity meter for the determination of the transverse (in-plane) thermal diffusivity; the product of density, specific heat capacity and thermal diffusivity is the thermal conductivity of the sample, and the results are shown in Table 2.

[0213] (2) Temperature drop effect test: A thermal management simulation tester was used, and the constant output power was set to 2W. The temperature T1 of the heat source without graphene heat dissipation film was 85℃, the area of ​​the heat source was 2cm×2cm, the area of ​​the graphene heat dissipation film of the sample to be tested was 9cm×6cm, one side of the sample was aligned with the corner of the heat source, and the temperature T2 of the heat source after applying the graphene heat dissipation film was tested for 15min. The difference between the two heat source temperatures was recorded as the cooling effect (∆T=T1-T2), and the unit was ℃. The results are shown in Table 2.

[0214] As shown in Table 2, the graphene heat dissipation films prepared in Examples 1-9 have a thickness of 80 μm and a density of 1.99 g / cm³. 3 ~2.14g / cm 3 The lateral diffusion coefficient is 930 mm. 2 / s~989mm 2 The thermal conductivity is 1478 W / (m·K)~1651 W / (m·K), and the cooling effect ∆T = 34℃~43℃. Compared with the graphene heat dissipation films prepared in Comparative Examples 1~9, the graphene heat dissipation films prepared in Examples 1~9 have a higher lateral thermal diffusivity, higher thermal conductivity, and better cooling effect at the same thickness.

[0215] Table 1. Preparation conditions and parameters of graphene heat dissipation film

[0216]

[0217] Table 2. Performance Comparison of Graphene Heat Dissipation Films

[0218]

[0219] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0220] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for preparing a graphene heat dissipation film, characterized in that, Includes the following steps: Prepare a mixed slurry containing graphene oxide and a defect repair agent; The mixed slurry is subjected to a film-forming treatment to obtain a first thin film; The first film is subjected to carbonization, graphitization and calendering to obtain the second film; A radiation heat dissipation layer is formed on the second thin film to obtain a graphene heat dissipation film; The graphene oxide includes at least two of the following: first graphene oxide, second graphene oxide, and third graphene oxide, and the mass ratio of the first graphene oxide, the second graphene oxide, and the third graphene oxide is 1:(0.1~1):(0~1). The lateral dimension of the first graphene oxide is larger than that of the second graphene oxide; The lateral dimension of the second graphene oxide is larger than that of the third graphene oxide; The lateral dimensions of the first graphene oxide are 0.1 μm to 3.0 μm; The lateral dimensions of the second graphene oxide are 50 nm to 100 nm. The lateral dimension of the third graphene oxide is less than 50 nm; The defect repair agent includes at least one of glucose, citric acid, citrate, and vitamin C; The mass ratio of the graphene oxide to the defect repair agent is 10:

2.

2. The method for preparing the graphene heat dissipation film as described in claim 1, characterized in that, One or more of the following conditions must be met: (1) The thickness of the graphene oxide is 0.3 nm to 4 nm; (2) The ratio of the atomic percentages of carbon and oxygen in the graphene oxide is 1.6 to 3.

0.

3. The method for preparing the graphene heat dissipation film according to any one of claims 1 to 2, characterized in that, The carbonization treatment is carried out at a temperature of 600℃~1000℃ for 2h~5h. The graphitization process is carried out under a protective atmosphere at a temperature of 1500℃~2500℃ for 2h~30h.

4. The method for preparing the graphene heat dissipation film as described in claim 3, characterized in that, The second film has a thickness of 10-80 μm and a density of 1.5-2.2 g / cm 3 ~2.2g / cm 3 .

5. The method for preparing the graphene heat dissipation film as described in claim 4, characterized in that, Forming a radiative heat dissipation layer on the second thin film includes the following steps: The radiative heat dissipation coating is sprayed onto the second film to form the radiative heat dissipation layer.

6. The method for preparing the graphene heat dissipation film as described in claim 5, characterized in that, The radiative heat dissipation coating includes one or more of the following: a polyvinylidene fluoride-hexafluoropropylene solution, a first mixture containing inorganic carbon materials, and a second mixture containing nano-oxides.

7. A graphene heat dissipation film, characterized in that, The graphene heat dissipation film was prepared using the method described in any one of claims 1 to 6.

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