Longitudinal high-thermal-conductivity graphene heat dissipation film and preparation method thereof

Abstract

The application discloses a longitudinal high-thermal-conductivity graphene heat dissipation film and a preparation method thereof, and belongs to the technical field of heat dissipation film preparation. The longitudinal high-thermal-conductivity graphene heat dissipation film comprises multiple graphene layers, and metal elements are inserted between at least some adjacent graphene layers. The preparation method is as follows: a pretreated graphene oxide slurry is self-assembled into a film to obtain a graphene oxide film; the graphene oxide film is subjected to low-temperature pretreatment to obtain an expanded graphene oxide film; the expanded graphene oxide film is immersed in a supersaturated metal ion-containing solution, and is dried after immersion to obtain a graphene oxide film with interlayer-adsorbed metal salt; the graphene oxide film with interlayer-adsorbed metal salt is subjected to heating decomposition to generate metal elements, and is subjected to carbonization treatment at the same time to obtain a film with interlayer-inserted metal; the film with interlayer-inserted metal is subjected to graphitization treatment to obtain a graphene film with interlayer-inserted metal; and the graphene film with interlayer-inserted metal is subjected to calendering to obtain the longitudinal high-thermal-conductivity graphene heat dissipation film. Through the combination of the graphene film and the metal, the interlayer insertion of the metal elements into the graphene layers is realized, and the longitudinal thermal conductivity of the graphene heat dissipation film is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of heat dissipation film preparation technology, specifically relating to a vertically high thermal conductivity graphene heat dissipation film and its preparation method. Background Technology

[0002] In today's increasingly integrated electronic components, heat dissipation has become the biggest problem limiting chip processing power. Electronic chips can perform at their maximum capacity under low temperatures, but as the temperature rises, the chip inevitably faces a decrease in clock speed. Especially in space-constrained conditions, heat accumulation is even more severe. Traditional synthetic graphite has good thermal conductivity, but it is difficult to make thick enough to dissipate heat effectively. In this context, graphene heat dissipation films have emerged, and were first applied in 2018. A single layer of graphene has a thermal conductivity as high as 5300 W / (m·K). Graphene heat dissipation films are made by stacking multiple layers of graphene, achieving a planar thermal conductivity of up to 1500 W / (m·K), but the longitudinal thermal conductivity is less than 5 W / (m·K). This low longitudinal thermal conductivity severely limits the heat dissipation performance of graphene heat dissipation films.

[0003] To address the aforementioned issues, Chinese Patent CN117507504A discloses a graphene longitudinal thermal conductor, its preparation method, and its application. This method obtains a graphene heat dissipation film with high longitudinal thermal conductivity by cyclically stacking resin layers and graphene thermally conductive layers and then calendering them to achieve density. However, this requires stacking 800-1200 layers, resulting in low preparation efficiency, and the addition of resin layers reduces the temperature resistance of the graphene film. Another existing Chinese Patent CN112477356A discloses a high thermal conductivity composite material based on a vertical polymer thin film array and its preparation method. This method uses solder paste to stack multiple perforated graphene sheets, then cuts them along the stacking direction to obtain a graphene longitudinal thermal conductor with the thermal conductivity direction along its thickness. However, this method suffers from difficulties in bonding the solder paste to the graphene, making processing challenging, and the introduction of solder paste reduces the actual heat dissipation area of ​​the graphene. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a high thermal conductivity graphene heat dissipation film in the longitudinal direction and its preparation method, so as to solve the technical problem that the low thermal conductivity in the longitudinal direction of the prior art seriously limits the heat dissipation performance of the graphene heat dissipation film.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] The present invention provides a longitudinally high thermal conductivity graphene heat dissipation film, the longitudinally high thermal conductivity graphene heat dissipation film comprising multiple graphene layers, wherein at least some of the adjacent graphene layers are interposed with a metal element.

[0007] In the specific implementation process, the metallic element is any one of copper, iron, cobalt and nickel.

[0008] In practical implementation, the in-plane thermal diffusivity of the longitudinally high thermal conductivity graphene heat dissipation film is 730–780 mm. 2 / s, longitudinal thermal diffusivity is 14~18mm 2 / s.

[0009] This invention provides a method for preparing a vertically high thermal conductivity graphene heat dissipation film, comprising the following steps:

[0010] S1: The pretreated graphene oxide slurry is coated onto a substrate and dried to self-assemble into a film, thereby obtaining a graphene oxide film.

[0011] S2: Low-temperature pretreatment of graphene oxide film to obtain expanded graphene oxide film;

[0012] S3: Under ultrasonic conditions, the expanded graphene oxide film is immersed in a supersaturated solution containing metal ions. After immersion, it is dried to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0013] S4: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is heated and decomposed to generate elemental metals. Simultaneously, carbonization is performed to obtain a film with interlayer intercalated metals.

[0014] S5: Under a protective atmosphere, the intercalated metal film is graphitized to obtain a graphene film with intercalated metal.

[0015] S6: The graphene film with intercalated metal layers is subjected to degassing calendering and compaction calendering to obtain a longitudinally high thermal conductivity graphene heat dissipation film.

[0016] In specific implementation, the preprocessing process in S1 is as follows:

[0017] Graphene oxide filter cake was dispersed in deionized water to prepare graphene oxide slurry. During the process, a pH adjuster was added to adjust the pH to 6-7.

[0018] The graphene oxide slurry was subjected to homogenization and degassing treatments in sequence to obtain a pretreated graphene oxide slurry.

[0019] The pH adjuster is an ammonia solution or a sodium hydroxide solution, wherein the mass percentage of the ammonia solution is 20% to 25%, and the concentration of the sodium hydroxide solution is 0.8 mol / L to 1.0 mol / L.

[0020] The solid content of the graphene oxide slurry is 5% to 15%.

[0021] In the specific implementation process, the homogenization pressure of the homogenization treatment is 60-90 MPa, and the viscosity of the homogenized graphene oxide slurry is 20000-50000 mPa·s.

[0022] The homogenization process is followed by a cooling process, the temperature of which is 20-30°C.

[0023] The degassing pressure of the degassing treatment is less than 3 kPa; the viscosity of the degassed graphene oxide slurry is 30,000 to 55,000 mPa·s.

[0024] In the specific implementation process, in S2, the low temperature pretreatment is a process of gradually increasing the temperature from room temperature to 260-300°C and then reducing it to room temperature.

[0025] The low-temperature pretreatment process includes four stages performed sequentially: a first stage, a second stage, a third stage, and a fourth stage. The process of the first stage is as follows:

[0026] The temperature is raised from room temperature to 50-60℃ within 30-45 minutes, then held for 12-12.5 hours. The temperature is then raised from 50-60℃ to 70-80℃ within 30-45 minutes, then held for 12-12.5 hours. The temperature is then lowered from 70-80℃ to 50-60℃, held for 12-12.5 hours, and then raised to 70-80℃ again, held for 12-12.5 hours.

[0027] The process of the second stage is as follows:

[0028] The temperature is increased from 70-80℃ to 120-150℃ within 30-45 minutes, and then held for 12-12.5 hours.

[0029] The process of the third stage is as follows:

[0030] The temperature is increased from 120-150℃ to 260-300℃ within 1-1.2 hours, and then held at that temperature for 12-12.5 hours.

[0031] The process of the fourth stage is as follows:

[0032] The temperature was lowered from 260-300℃ to room temperature.

[0033] In the specific implementation process, in S3, the supersaturated metal ion-containing solution is any one of the following: metal ion-containing nitric acid solution, sulfuric acid solution, and chloride solution;

[0034] The metal ions in the supersaturated metal ion-containing solution are any one of copper ions, iron ions, cobalt ions, and nickel ions.

[0035] In the specific implementation process, the process of heating and decomposing the graphene oxide film with interlayer adsorbed metal salts to generate elemental metals in S4 is as follows:

[0036] The graphene oxide film with interlayer adsorbed metal salts was heated to decompose the metal salts into metal oxides, and then the metal oxides were heated to decompose into elemental metals.

[0037] The metal oxide is any one of CuO, Fe2O3, Co2O3, and NiO;

[0038] The carbonization process is as follows:

[0039] The temperature was increased from room temperature at a rate of 100–120℃ / h, and then held at 200–400℃, 1110–1200℃, and 1450–1550℃ for 1–3 hours respectively.

[0040] In the specific implementation process, in step S5, the protective atmosphere is an argon atmosphere; the temperature of the graphitization treatment is 2500~2850℃;

[0041] In step S6, the pressure of the exhaust calendering is not less than 500t, and the total holding time of the exhaust calendering is not less than 12h; the pressure of the dense calendering is not less than 700t, and the holding time of the dense calendering is not less than 30min.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] This invention provides a method for preparing a longitudinally high thermal conductivity graphene heat dissipation film. First, a graphene oxide film expands after low-temperature pretreatment. The expanded graphene oxide film is then placed in a solution containing metal ions. The porous structure of the graphene oxide adsorbs the metal ions into the interlayer space of the graphene oxide. Subsequently, the impregnated graphene oxide film undergoes carbonization and graphitization. During this process, the metal ion solution also gradually undergoes a thermal decomposition reaction at high temperature to obtain elemental metals. By using an impregnation-high-temperature thermal reduction method to achieve intercalation of metals into the graphene layers, the process of elemental metal generation is combined with the thermal reduction process of the graphene oxide film, achieving the effects of energy saving and simplified process flow.

[0044] This invention provides a high thermal conductivity graphene heat dissipation film in the longitudinal direction. By combining graphene film and metal, the metal element is intercalated between graphene layers, which effectively improves the longitudinal thermal conductivity of the graphene heat dissipation film and makes up for the shortcomings of graphene heat dissipation film.

[0045] Furthermore, the metals that can be selected include Cu, Fe, Co, and Ni. The atomic diameter of these metals is between 0.2 and 0.3 nm, while the interlayer spacing of graphene oxide is 0.7-0.9 nm and the interlayer spacing of graphene is 0.34 nm. Both of these are larger than the atomic diameter of the selected metals, thus providing the possibility for metal intercalation. Detailed Implementation

[0046] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0047] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0048] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0049] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0050] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0051] This invention provides a vertically high thermal conductivity graphene heat dissipation film and its preparation method.

[0052] The first aspect of this invention provides a longitudinally high thermal conductivity graphene heat dissipation film, wherein a metallic element is intercalated between the graphene layers. Specifically, the longitudinally high thermal conductivity graphene heat dissipation film comprises multiple graphene layers, wherein a metallic element is intercalated between at least some of adjacent graphene layers. The atomic diameter of the metallic element is smaller than the interlayer spacing of the graphene layers. By intercalating the metallic element between the graphene layers, the longitudinal thermal conductivity of the graphene heat dissipation film is significantly improved. The intercalated metallic element is any one of copper, iron, cobalt, and nickel.

[0053] More specifically, the intercalation of elemental metals between graphene layers in a longitudinally high thermal conductivity graphene heat dissipation film includes, but is not limited to, the following situations: In a longitudinally high thermal conductivity graphene heat dissipation film, elemental metals can be uniformly distributed between graphene layers or non-uniformly distributed. Uniform distribution means that elemental metals are inserted between all adjacent graphene layers, while non-uniform distribution means that elemental metals are inserted between some adjacent graphene layers.

[0054] Furthermore, the state of a metallic element can be a single atom or a multi-atom aggregate, meaning that the particle distribution of a metallic element can be uniform or non-uniform.

[0055] Specifically, the metals that can be selected are Cu, Fe, Co, and Ni. The atomic diameter of these metals is between 0.2 and 0.3 nm, while the interlayer spacing of graphene oxide is 0.7 to 0.9 nm and the interlayer spacing of graphene is 0.34 nm. Both of these are larger than the atomic diameter of the selected metals, thus providing the possibility for metal intercalation.

[0056] Experimental tests showed that the in-plane thermal diffusivity of the aforementioned longitudinally high thermal conductivity graphene heat dissipation film was 730–780 mm. 2 / s, longitudinal thermal diffusivity is 14~18mm 2 / s.

[0057] The second aspect of this invention provides a method for preparing a longitudinally high thermal conductivity graphene heat dissipation film. The method achieves intercalation of metal between graphene layers through impregnation-high temperature thermal reduction, which further improves the overall heat dissipation capacity of the graphene heat dissipation film. Furthermore, the process of generating elemental metal is combined with the process of thermal reduction of graphene oxide film, which achieves the effects of saving energy and simplifying the process flow.

[0058] The above-mentioned method for preparing a longitudinally high thermal conductivity graphene heat dissipation film includes the following steps:

[0059] S1: The pretreated graphene oxide slurry is coated onto a substrate and dried to self-assemble into a film, thereby obtaining a graphene oxide film.

[0060] S2: Low-temperature pretreatment of graphene oxide film to obtain expanded graphene oxide film;

[0061] S3: Under ultrasonic conditions, the expanded graphene oxide film is immersed in a supersaturated solution containing metal ions. After immersion, it is dried to obtain a graphene oxide film with interlayer adsorption of metal salts. Graphene oxide will expand after low-temperature preheating. When the graphene oxide film in this state is immersed in a solution containing metal ions, the porous structure of graphene oxide will adsorb the solution containing metal ions into the interlayer of graphene oxide.

[0062] S4: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is heated and decomposed to generate elemental metals. During the heating and decomposition, carbonization is performed to obtain a film with interlayer intercalated metals. The impregnated graphene oxide film is then carbonized. During this process, the metal ion solution will also undergo a thermal decomposition reaction at high temperature to obtain elemental metals.

[0063] S5: Under a protective atmosphere, the intercalated metal film is graphitized to obtain a graphene film with intercalated metal.

[0064] S6: The graphene film with intercalated metal layers is subjected to degassing calendering and compaction calendering to obtain a longitudinally high thermal conductivity graphene heat dissipation film.

[0065] In the specific implementation process, in S1, the pretreated graphene oxide slurry is coated onto the substrate and then dried to self-assemble into a film, as follows:

[0066] The pretreated graphene oxide slurry is coated onto the substrate with a suitable thickness and width and then dried and self-assembled into a film. The graphene oxide film is peeled off from the substrate and cut into sheets of a suitable size. The cut graphene oxide film is placed in an oven and the temperature is adjusted from room temperature to high temperature to perform low-temperature pre-reduction of the graphene oxide film, thoroughly evaporating the moisture and removing the gas generated by the oxygen-containing functional groups in the broken parts.

[0067] The suitable coating thickness is 2–8 mm, and the width is 0.2–1.4 m. Drying methods include natural air drying, continuous oven drying, and microwave drying. The preferred drying temperature is ≤90℃. The sheet size is ≤30cm × 30cm.

[0068] The preprocessing process is as follows:

[0069] S11: Graphene oxide filter cake is dispersed in deionized water to prepare graphene oxide slurry, with a pH adjuster added to adjust the pH to 6-7 during the process. The graphene oxide filter cake is prepared from graphite using the Brodie, Staudenmaier, or Hummers processes. Preferably, graphene oxide filter cake prepared using the Hummers process is used. The pH adjuster is preferably an ammonia solution or a sodium hydroxide solution, with the ammonia solution having a mass percentage of 20%-25% and the sodium hydroxide solution having a concentration of 0.8 mol / L-1.0 mol / L; the solid content of the graphene oxide slurry is 5%-15%.

[0070] S12: The graphene oxide slurry is subjected to homogenization and degassing treatments sequentially to obtain a pretreated graphene oxide slurry. The homogenization pressure during homogenization is 60–90 MPa, and the viscosity of the homogenized graphene oxide slurry is 20,000–50,000 mPa·s. The homogenization process is followed by a cooling treatment at a temperature of 20–30°C. The degassing pressure during degassing is less than 3 kPa, and the viscosity of the degassed graphene oxide slurry is 30,000–55,000 mPa·s.

[0071] In the specific implementation process, in S2, the low temperature pretreatment is a process of gradually raising the temperature from room temperature to 260-300℃ and then lowering it to room temperature.

[0072] The specific low-temperature pretreatment process includes the following steps: a first stage in which the temperature is raised from room temperature to 50-60°C within 30-45 minutes and held for 12-12.5 hours; a second stage in which the temperature is raised from 50-60°C to 70-80°C within 30-45 minutes and held for 12-12.5 hours; a third stage in which the temperature is raised from 70-80°C to 120-150°C within 30-45 minutes and held for 12-12.5 hours; a fourth stage in which the temperature is lowered from 260-300°C to room temperature within 1-1.2 hours.

[0073] In the specific implementation process, in S3, the supersaturated metal ion-containing solution is any one of the metal ion-containing nitric acid solution, sulfuric acid solution and chlorination solution; the metal ion in the supersaturated metal ion-containing solution is any one of copper ion, iron ion, cobalt ion and nickel ion.

[0074] More specifically, the supersaturated copper ion-containing solution is one of the following: supersaturated Cu(NO3)2 copper nitrate solution, supersaturated CuSO4 copper sulfate solution, or supersaturated CuCl2 copper chloride solution; the supersaturated iron ion-containing solution is one of the following: supersaturated Fe(NO3)3 ferric nitrate solution, supersaturated Fe2(SO4)3 ferric sulfate solution, supersaturated FeCl3 ferric chloride solution, or supersaturated FeCl2 ferrous chloride solution; and the supersaturated cobalt ion-containing solution is one of the following: Co(NO3)2 cobalt nitrate solution, CoSO4 cobalt sulfate solution, or CoCl2 cobalt chloride solution. The supersaturated nickel ion-containing solution is one of Ni(NO3)2 nickel nitrate solution, NiSO4 nickel sulfate solution, or NiCl2 nickel chloride solution; the metal salt corresponding to copper ions is any one of Cu(NO3)2, CuSO4, and CuCl2; the metal salt corresponding to iron ions is any one of Fe(NO3)3, Fe2(SO4)3, FeCl3, and FeCl2; the metal salt corresponding to cobalt ions is any one of Co(NO3)2, CoSO4, and CoCl2; and the metal salt corresponding to nickel ions is any one of Ni(NO3)2, NiSO4, and NiCl2.

[0075] The drying temperature is 50–120°C. Preferably, the drying temperature is controlled between 80–90°C, and the drying time is 24 hours.

[0076] In the specific implementation process, the process of heating and decomposing the graphene oxide film with interlayer adsorbed metal salts to generate elemental metals in S4 is as follows:

[0077] The graphene oxide film with interlayer adsorbed metal salts is heated to decompose the metal salts into metal oxides, and then heated to decompose the metal oxides into elemental metals. The metal oxides can be any one of CuO, Fe2O3, Co2O3, or NiO.

[0078] More specifically, the heating process for carbonization is as follows:

[0079] The temperature was increased from room temperature at a rate of 100–120℃ / h, and then held at 200–400℃, 1110–1200℃, and 1450–1550℃ for 1–3 hours respectively.

[0080] In the specific implementation process, in S5, the protective atmosphere is an argon atmosphere; high-purity argon gas with a purity of 99.999% or higher is introduced to a slightly positive pressure, and the intercalated metal film is heated to the graphitization temperature of 2500-2850℃ under this atmosphere to carry out graphitization treatment.

[0081] In the specific implementation process, in S6, the pressure of the exhaust calendering is not less than 500t, and the total holding time of the exhaust calendering is not less than 12h; the pressure of the dense calendering is not less than 700t, and the holding time of the dense calendering is not less than 30min.

[0082] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0083] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0084] Example 1

[0085] Step 1: Take 11.111 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150L stirred tank. Add 87.890 kg of deionized water and 1.001 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained. The pH is measured to be 6.45.

[0086] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 20325 mPa·s.

[0087] Step 3: The homogenized graphene oxide slurry is degassed in a degassing machine at a pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 30536 mPa·s.

[0088] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1 m on a coating machine and then dried.

[0089] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 20cm.

[0090] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven temperature is increased from room temperature to 50°C within 30 minutes, and then held for 12 hours. Then, the temperature is increased from 50°C to 70°C within 30 minutes, and then held for 12 hours. The temperature is then decreased from 70°C to 50°C, and held for 12 hours. The temperature is then increased to 70°C again and held for 12 hours. In the second stage, the temperature is increased from 70°C to 120°C within 30 minutes and held for 12 hours. In the third stage, the temperature is increased from 120°C to 300°C within 1 hour and held for 12 hours. Finally, the temperature is decreased from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0091] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated cobalt nitrate solution for 24 hours under ultrasonic conditions.

[0092] Step 8: Remove the impregnated sheet and place it in an oven to dry at 90°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0093] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 250℃ and held for 1h, then raised to 1200℃ and held for 2h, and finally raised to 1500℃ and held for 2h to obtain a film with interlayer intercalated cobalt metal.

[0094] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated cobalt film from room temperature to 2850℃ for 48 hours to prepare a graphene film with intercalated cobalt.

[0095] Step 11: The graphene film with intercalated cobalt metal is degassed at a pressure of 500t for 12 hours, and then densified at a pressure of 700t for 30 minutes to obtain a graphene heat dissipation film with intercalated cobalt metal.

[0096] The thermal diffusivity of the graphene film obtained in step eleven was tested using a Netzsch LFA-467 laser flare analyzer. Three films were randomly selected for testing, and the measured in-plane thermal diffusivity was 767.83 mm. 2 / s, 759.34mm 2 / s, 773.91mm 2 / s, and the longitudinal thermal conductivity and thermal diffusivity are 16.53 mm. 2 / s, 17.11mm 2 / s, 17.53mm 2 / s.

[0097] Example 2

[0098] Step 1: Take 11.109 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 87.891 kg of deionized water and 1.010 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained, and the pH is measured to be 6.52.

[0099] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to 20-30℃ to obtain a graphene oxide slurry with a viscosity of 20134mPa·s.

[0100] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 30112 mPa·s.

[0101] Step 4: The homogenized and degassed graphene slurry is coated onto a graphene oxide film with a thickness of 2 mm and a width of 0.2 m on a coating machine and then dried.

[0102] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0103] Step Six: Place the obtained sheet in an oven. The oven is heated from room temperature to 60°C within 45 minutes in an air atmosphere, and then held at that temperature for 12.5 hours. Then, the temperature is raised from 60°C to 80°C within 45 minutes and held for 12.5 hours. The temperature is then lowered from 80°C to 60°C and held for 12.5 hours. The temperature is then raised to 80°C again and held for 12.5 hours. The next step is to raise the temperature from 80°C to 150°C within 45 minutes and hold for 12.5 hours. The third step is to raise the temperature from 150°C to 300°C within 1.2 hours and hold for 12.5 hours. Finally, the temperature is lowered from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0104] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated copper nitrate solution for 24 hours under ultrasonic conditions.

[0105] Step 8: Remove the impregnated sheet and place it in an oven to dry at 50°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0106] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 200℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1450℃ and held for 2h to obtain a film with interlayer intercalated copper metal.

[0107] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated copper film from room temperature to 2500℃ for 48 hours to obtain the graphene film with intercalated copper.

[0108] Step 11: The graphene film with intercalated copper is degassed at 600t for 12 hours, and then densified at 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated cobalt.

[0109] Example 3

[0110] Step 1: Take 11.110 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 87.888 kg of deionized water and 1.005 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained. The pH is measured to be 6.39.

[0111] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 21120 mPa·s.

[0112] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 31015 mPa·s.

[0113] Step 4: The homogenized and degassed graphene slurry is coated onto a graphene oxide film with a thickness of 8 mm and a width of 1.4 m on a coating machine and then dried.

[0114] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0115] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven is heated from room temperature to 55°C within 35 minutes, and then held at that temperature for 12 hours. Then, the temperature is raised from 55°C to 75°C within 40 minutes, and then held for 12 hours. The temperature is then lowered from 75°C to 55°C, and held for 12 hours. The temperature is then raised to 75°C again and held for 12 hours. In the second stage, the temperature is raised from 75°C to 130°C within 40 minutes and held for 12 hours. In the third stage, the temperature is raised from 130°C to 280°C within 1.2 hours and held for 12 hours. Finally, the temperature is lowered from 280°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0116] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated nickel nitrate solution for 24 hours under ultrasonic conditions.

[0117] Step 8: Remove the impregnated sheet and place it in an oven to dry at 120°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0118] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 400℃ and held for 3h, then raised to 1200℃ and held for 2h, and finally raised to 1500℃ and held for 2h to obtain a film with interlayer intercalated nickel metal.

[0119] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the intercalated nickel film from room temperature to 2700℃ for 48 hours to obtain an intercalated nickel graphene film.

[0120] Step 11: The graphene film with intercalated nickel is degassed at 600t for 12 hours, and then densified at 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated nickel.

[0121] Example 4

[0122] Step 1: Take 11.101 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 87.889 kg of deionized water and 1.003 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained. The pH is measured to be 6.45.

[0123] Step 2: The graphene oxide slurry is homogenized twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, the slurry is cooled to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 20896mPa·s.

[0124] Step 3: The homogenized graphene oxide slurry is degassed in a degassing machine at a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 30446 mPa·s.

[0125] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1.4 m on a coating machine and then dried.

[0126] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0127] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven is heated from room temperature to 60°C within 30 minutes, and then held at that temperature for 12 hours. Then, the temperature is raised from 60°C to 80°C within 30 minutes, and then held for 12 hours. The temperature is then lowered from 80°C to 60°C, and held for 12 hours. The temperature is then raised to 80°C again and held for 12 hours. In the second stage, the temperature is raised from 80°C to 120°C within 30 minutes and held for 12 hours. In the third stage, the temperature is raised from 120°C to 260°C within 1 hour and held for 12 hours. Finally, the temperature is lowered from 260°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0128] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated ferric nitrate solution for 24 hours under ultrasonic conditions.

[0129] Step 8: Remove the impregnated sheet and place it in an oven to dry at 100°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0130] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 270℃ and held for 2h, then raised to 1200℃ and held for 2h, and finally raised to 1550℃ and held for 2h to obtain a film with interlayer intercalated metal iron.

[0131] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the intercalated iron film from room temperature to 2730℃ for 48 hours to obtain an intercalated iron graphene film.

[0132] Step 11: The graphene film with intercalated metallic iron is degassed at a pressure of not less than 600t for 12 hours, and then densified at a pressure of not less than 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated metallic iron.

[0133] Example 5

[0134] Step 1: Take 13.334 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 85.345 kg of deionized water and 1.323 kg of ammonia water with a mass fraction of 20%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 6% is obtained, and the pH is measured to be 6.07.

[0135] Step 2: The graphene oxide slurry is homogenized twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, the slurry is cooled to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 34531mPa·s.

[0136] Step 3: The homogenized graphene oxide slurry is degassed in a degassing machine at a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 37552 mPa·s.

[0137] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1 m on a coating machine and then dried.

[0138] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 20cm.

[0139] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven temperature is increased from room temperature to 50°C within 30 minutes, and then held for 12 hours. Then, the temperature is increased from 50°C to 70°C within 30 minutes, and then held for 12 hours. The temperature is then decreased from 70°C to 50°C, and held for 12 hours. The temperature is then increased to 70°C again and held for 12 hours. In the second stage, the temperature is increased from 70°C to 120°C within 30 minutes and held for 12 hours. In the third stage, the temperature is increased from 120°C to 300°C within 1 hour and held for 12 hours. Finally, the temperature is decreased from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0140] Step 7: Immerse the resulting expanded graphene oxide film in a supersaturated cobalt nitrate solution for 24 hours under ultrasonic conditions.

[0141] Step 8: Remove the impregnated sheet and place it in an oven to dry at 90°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0142] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 250℃ and held for 1h, then raised to 1200℃ and held for 2h, and finally raised to 1500℃ and held for 2h to obtain a film with interlayer intercalated cobalt metal.

[0143] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated cobalt film from room temperature to 2850℃ for 48 hours to prepare a graphene film with intercalated cobalt.

[0144] Step 11: The graphene film with intercalated cobalt metal is degassed at a pressure of 500t for 12 hours, and then densified at a pressure of 700t for 30 minutes to obtain a graphene heat dissipation film with intercalated cobalt metal.

[0145] Example 6

[0146] Step 1: Take 14.445 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 85.455 kg of deionized water and 100 g of sodium hydroxide solution with a concentration of 1.0 mol / L. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 6.5% is obtained, and the pH is measured to be 6.88.

[0147] Step 2: The graphene oxide slurry is homogenized twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, the slurry is cooled to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 49552mPa·s.

[0148] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 55012 mPa·s.

[0149] Step 4: The homogenized and degassed graphene slurry is coated onto a graphene oxide film with a thickness of 2 mm and a width of 0.2 m on a coating machine and then dried.

[0150] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0151] Step Six: Place the obtained sheet in an oven. The oven is heated from room temperature to 60°C within 45 minutes in an air atmosphere, and then held at that temperature for 12.5 hours. Then, the temperature is raised from 60°C to 80°C within 45 minutes and held for 12.5 hours. The temperature is then lowered from 80°C to 60°C and held for 12.5 hours. The temperature is then raised to 80°C again and held for 12.5 hours. The next step is to raise the temperature from 80°C to 150°C within 45 minutes and hold for 12.5 hours. The third step is to raise the temperature from 150°C to 300°C within 1.2 hours and hold for 12.5 hours. Finally, the temperature is lowered from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0152] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated copper sulfate solution for 24 hours under ultrasonic conditions.

[0153] Step 8: Remove the impregnated sheet and place it in an oven to dry at 50°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0154] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 200℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1450℃ and held for 2h to obtain a film with interlayer intercalated copper metal.

[0155] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated copper film from room temperature to 2500℃ for 48 hours to obtain the graphene film with intercalated copper.

[0156] Step 11: The graphene film with intercalated copper is degassed at 600t for 12 hours, and then densified at 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated copper.

[0157] Example 7

[0158] Step 1: Take 14.445 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 85.455 kg of deionized water and 120 g of sodium hydroxide solution with a concentration of 0.8 mol / L. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 6.5% is obtained, and the pH is measured to be 6.95.

[0159] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 49892mPa·s.

[0160] Step 3: The homogenized graphene oxide slurry is degassed in a degassing machine at a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 54932 mPa·s.

[0161] Step 4: The homogenized and degassed graphene slurry is coated onto a graphene oxide film with a thickness of 2 mm and a width of 0.2 m on a coating machine and then dried.

[0162] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0163] Step Six: Place the obtained sheet in an oven. The oven is heated from room temperature to 60°C within 45 minutes in an air atmosphere, and then held at that temperature for 12.5 hours. Then, the temperature is raised from 60°C to 80°C within 45 minutes and held for 12.5 hours. The temperature is then lowered from 80°C to 60°C and held for 12.5 hours. The temperature is then raised to 80°C again and held for 12.5 hours. The next step is to raise the temperature from 80°C to 150°C within 45 minutes and hold for 12.5 hours. The third step is to raise the temperature from 150°C to 300°C within 1.2 hours and hold for 12.5 hours. Finally, the temperature is lowered from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0164] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated copper sulfate solution for 24 hours under ultrasonic conditions.

[0165] Step 8: Remove the impregnated sheet and place it in an oven to dry at 50°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0166] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 200℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1450℃ and held for 2h to obtain a film with interlayer intercalated copper metal.

[0167] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated copper film from room temperature to 2500℃ for 48 hours to obtain the graphene film with intercalated copper.

[0168] Step 11: The graphene film with intercalated copper is degassed at 600t for 12 hours, and then densified at 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated copper.

[0169] Example 8

[0170] Step 1: Take 11.101 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 87.889 kg of deionized water and 1.003 kg of ammonia water with a mass fraction of 23%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained. The pH is measured to be 6.15.

[0171] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 21120 mPa·s.

[0172] Step 3: The homogenized graphene oxide slurry is degassed in a degassing machine at a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 31330 mPa·s.

[0173] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1.4 m on a coating machine and then dried.

[0174] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0175] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven temperature is raised from room temperature to 60°C within 30 minutes, and then held for 12 hours. Then, the temperature is raised from 60°C to 80°C within 30 minutes, and then held for 12 hours. The temperature is then lowered from 80°C to 60°C, and held for 12 hours. The temperature is then raised to 80°C again and held for 12 hours. In the second stage, the temperature is raised from 80°C to 120°C within 30 minutes and held for 12 hours. In the third stage, the temperature is raised from 120°C to 260°C within 1 hour and held for 12 hours. Finally, the temperature is lowered from 260°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0176] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated ferric sulfate solution for 24 hours under ultrasonic conditions.

[0177] Step 8: Remove the impregnated sheet and place it in an oven to dry at 100°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0178] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 270℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1550℃ and held for 2h to obtain a film with interlayer intercalated metal iron.

[0179] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the intercalated iron film from room temperature to 2730℃ for 48 hours to obtain an intercalated iron graphene film.

[0180] Step 11: The graphene film with intercalated metallic iron is degassed at a pressure of not less than 600t for 12 hours, and then densified at a pressure of not less than 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated metallic iron.

[0181] Example 9

[0182] Step 1: Take 33.333 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 63.657 kg of deionized water, 3.010 kg of ammonia water with a mass fraction of 25%, and 1.667 kg of calcium lignosulfonate. After stirring and dispersing for 4 hours, 100 kg of graphene oxide slurry with a solid content of 15% is obtained. The pH is measured to be 6.65.

[0183] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 35075 mPa·s.

[0184] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 2 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 40078 mPa·s.

[0185] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1.4 m on a coating machine and then dried.

[0186] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 24cm.

[0187] Step Six: Place the obtained sheet in an oven. In an air atmosphere, the oven temperature is raised from room temperature to 60°C within 30 minutes, and then held for 12 hours. Then, the temperature is raised from 60°C to 80°C within 30 minutes, and then held for 12 hours. The temperature is then lowered from 80°C to 60°C, and held for 12 hours. The temperature is then raised to 80°C again and held for 12 hours. In the second stage, the temperature is raised from 80°C to 120°C within 30 minutes and held for 12 hours. In the third stage, the temperature is raised from 120°C to 260°C within 1 hour and held for 12 hours. Finally, the temperature is lowered from 260°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0188] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated ferric chloride solution for 24 hours under ultrasonic conditions.

[0189] Step 8: Remove the impregnated sheet and place it in an oven to dry at 100°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0190] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 300℃ and held for 2h, then raised to 1200℃ and held for 2h, and finally raised to 1550℃ and held for 2h to obtain a film with interlayer intercalated metal iron.

[0191] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the intercalated iron film from room temperature to 2730℃ for 48 hours to obtain an intercalated iron graphene film.

[0192] Step 11: The graphene film with intercalated metallic iron is degassed at a pressure of not less than 550t for 12 hours, and then densified at a pressure of not less than 750t for 30 minutes to obtain a graphene heat dissipation film with intercalated metallic iron.

[0193] Example 10

[0194] Step 1: Take 14.445 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 84.249 kg of deionized water and 1.332 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 6.5% is obtained, and the pH is measured to be 6.73.

[0195] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to between 20 and 30°C to obtain a graphene oxide slurry with a viscosity of 49892mPa·s.

[0196] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 50108 mPa·s.

[0197] Step 4: The homogenized and degassed graphene oxide slurry is coated onto a graphene oxide film with a thickness of 2.6 mm and a width of 1 m on a coating machine and then dried.

[0198] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0199] Step Six: Place the obtained sheet in an oven. The oven is heated from room temperature to 50°C within 30 minutes in an air atmosphere, and then held at that temperature for 12.5 hours. Then, the temperature is raised from 50°C to 70°C within 30 minutes and held for 12.5 hours. The temperature is then lowered from 70°C to 50°C and held for 12.5 hours. The temperature is then raised to 70°C again and held for 12.5 hours. The next steps are: the first stage, the second stage, the third stage, the fourth stage, and the fifth stage, the fifth stage, which involves raising the temperature from 70°C to 120°C within 30 minutes and holding for 12.5 hours; the sixth stage, the seventh stage, which involves raising the temperature from 120°C to 300°C within 1 hour and holding for 12.5 hours; and the eighth stage, the fifth stage, which involves lowering the temperature from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0200] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated cobalt sulfate solution for 24 hours under ultrasonic conditions.

[0201] Step 8: Remove the impregnated sheet and place it in an oven to dry at 90°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0202] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 100℃ / h. The temperature is raised to 400℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1500℃ and held for 2h to obtain a film with interlayer intercalated cobalt metal.

[0203] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated cobalt film from room temperature to 2850℃ for 48 hours to prepare a graphene film with intercalated cobalt.

[0204] Step 11: The graphene film with intercalated metal is degassed at a pressure of 600t for 12 hours, and then densified at a pressure of 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated cobalt metal.

[0205] Example 11

[0206] Step 1: Take 11.109 kg of graphene oxide filter cake with a solid content of 45% and place it in a 150 L stirred tank. Add 87.891 kg of deionized water and 1.010 kg of ammonia water with a mass fraction of 25%. After stirring and dispersing for 2 hours, 100 kg of graphene oxide slurry with a solid content of 5% is obtained, and the pH is measured to be 6.52.

[0207] Step 2: Homogenize the graphene oxide slurry twice in a high-pressure homogenizer. The pressure of the first homogenization is controlled at 65±5MPa, and the pressure of the second homogenization is controlled at 85±5MPa. After homogenization, cool the slurry to 20-30℃ to obtain a graphene oxide slurry with a viscosity of 20134mPa·s.

[0208] Step 3: Degas the homogenized graphene oxide slurry in a degassing machine with a degassing pressure of 3 kPa and a yield time of 100 s to obtain a graphene oxide slurry with a viscosity of 30112 mPa·s.

[0209] Step 4: The homogenized and degassed graphene slurry is coated onto a graphene oxide film with a thickness of 2 mm and a width of 0.2 m on a coating machine and then dried.

[0210] Step 5: Cut the dried graphene oxide film into sheets with a length and width of 30cm.

[0211] Step Six: Place the obtained sheet in an oven. The oven is heated from room temperature to 60°C within 45 minutes in an air atmosphere, and then held at that temperature for 12.5 hours. Then, the temperature is raised from 60°C to 80°C within 45 minutes and held for 12.5 hours. The temperature is then lowered from 80°C to 60°C and held for 12.5 hours. The temperature is then raised to 80°C again and held for 12.5 hours. The next step is to raise the temperature from 80°C to 150°C within 45 minutes and hold for 12.5 hours. The third step is to raise the temperature from 150°C to 300°C within 1.2 hours and hold for 12.5 hours. Finally, the temperature is lowered from 300°C to room temperature. This low-temperature pretreatment of the graphene oxide sheet yields an expanded graphene oxide film.

[0212] Step 7: Immerse the obtained expanded graphene oxide film in a supersaturated copper nitrate solution for 24 hours under ultrasonic conditions.

[0213] Step 8: Remove the impregnated sheet and place it in an oven to dry at 50°C for 24 hours to obtain a graphene oxide film with interlayer adsorption of metal salts.

[0214] Step 9: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is subjected to a heating treatment from room temperature to 1500℃ at a heating rate of 120℃ / h. The temperature is raised to 200℃ and held for 1h, raised to 1200℃ and held for 2h, and raised to 1450℃ and held for 2h to obtain a film with interlayer intercalated copper metal.

[0215] Step 10: Under an argon atmosphere, maintain a slight positive pressure inside the graphitization furnace and perform graphitization treatment on the interlayer intercalated copper film from room temperature to 2500℃ for 48 hours to obtain the graphene film with intercalated copper.

[0216] Step 11: The graphene film with intercalated copper is degassed at 600t for 12 hours, and then densified at 800t for 30 minutes to obtain a graphene heat dissipation film with intercalated cobalt.

[0217] The thermal diffusivity of the graphene film was tested using a Netzsch LFA-467 laser flare analyzer. Multiple experiments yielded an in-plane thermal diffusivity of 730–780 mm². 2 Between / s, the longitudinal thermal diffusivity is 14–18 mm. 2 Between / s.

[0218] The inventive point of this invention lies in adding a metal ion solution impregnation process to the traditional graphene heat dissipation film preparation process and optimizing the graphitization heating procedure to obtain a graphene film with metal intercalated between graphene layers, which can effectively improve the longitudinal thermal conductivity of the graphene film. Through the composite of graphene film and metal, the intercalation of elemental metals between graphene layers is achieved, effectively improving the longitudinal thermal conductivity of the graphene heat dissipation film and compensating for the shortcomings of traditional graphene heat dissipation films.

[0219] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a longitudinally high thermal conductivity graphene heat dissipation film, characterized in that, Includes the following steps: S1: The pretreated graphene oxide slurry is coated onto a substrate and dried to self-assemble into a film, thereby obtaining a graphene oxide film. S2: Low-temperature pretreatment of graphene oxide film to obtain expanded graphene oxide film; In S2, the low-temperature pretreatment is a process of gradually increasing the temperature from room temperature to 260~300℃ and then reducing it to room temperature. The low-temperature pretreatment process includes four stages performed sequentially: a first stage, a second stage, a third stage, and a fourth stage. The process of the first stage is as follows: The temperature is increased from room temperature to 50-60℃ within 30-45 minutes, and then held for 12-12.5 hours. Then, the temperature is increased from 50-60℃ to 70-80℃ within 30-45 minutes, and then held for 12-12.5 hours. The temperature is then decreased from 70-80℃ to 50-60℃, and held for 12-12.5 hours. Then, the temperature is increased to 70-80℃ again, and held for 12-12.5 hours. The process of the second stage is as follows: The temperature is increased from 70-80℃ to 120-150℃ within 30-45 minutes, and then held at that temperature for 12-12.5 hours. The process of the third stage is as follows: The temperature is increased from 120-150℃ to 260-300℃ within 1-1.2 hours, and then held at that temperature for 12-12.5 hours. The process of the fourth stage is as follows: The temperature dropped from 260-300℃ to room temperature; S3: Under ultrasonic conditions, the expanded graphene oxide film is immersed in a supersaturated solution containing metal ions. After immersion, it is dried to obtain a graphene oxide film with interlayer adsorption of metal salts. S4: Under vacuum conditions, the graphene oxide film with interlayer adsorbed metal salts is heated and decomposed to generate elemental metals. Simultaneously, carbonization is performed to obtain a film with interlayer intercalated metals. In step S4, the process of heating and decomposing the graphene oxide film with interlayer adsorbed metal salts to generate elemental metals is as follows: The graphene oxide film with interlayer adsorbed metal salts was heated to decompose the metal salts into metal oxides, and then the metal oxides were heated to decompose into elemental metals. The carbonization process is as follows: The temperature was increased from room temperature at a rate of 100~120℃ / h, and then held at 200~400℃, 1110~1200℃ and 1450~1550℃ for 1~3h respectively. S5: Under a protective atmosphere, the intercalated metal film is graphitized to obtain a graphene film with intercalated metal. S6: The graphene film with intercalated metal layers is subjected to degassing calendering and compaction calendering to obtain a longitudinally high thermal conductivity graphene heat dissipation film. The longitudinally high thermal conductivity graphene heat dissipation film comprises multiple graphene layers, wherein at least some adjacent graphene layers are interposed with a metallic element; the in-plane thermal diffusivity of the longitudinally high thermal conductivity graphene heat dissipation film is 730~780 mm. 2 / s, longitudinal thermal diffusivity is 14~18 mm 2 / s.

2. The method for preparing a longitudinally high thermal conductivity graphene heat dissipation film according to claim 1, characterized in that, In step S1, the preprocessing process is as follows: Graphene oxide filter cake was dispersed in deionized water to prepare graphene oxide slurry. During the process, a pH adjuster was added to adjust the pH to 6-7. The graphene oxide slurry was subjected to homogenization and degassing treatments in sequence to obtain a pretreated graphene oxide slurry. The pH adjuster is an ammonia solution or a sodium hydroxide solution, wherein the mass percentage of the ammonia solution is 20% to 25%, and the concentration of the sodium hydroxide solution is 0.8 mol / L to 1.0 mol / L. The solid content of the graphene oxide slurry is 5% to 15%.

3. The method for preparing a longitudinally high thermal conductivity graphene heat dissipation film according to claim 2, characterized in that, The homogenization pressure of the homogenization treatment is 60~90 MPa, and the viscosity of the homogenized graphene oxide slurry is 20000~50000 mPa•s. The homogenization process is followed by a cooling process, the temperature of which is 20~30℃. The degassing pressure of the degassing treatment is less than 3 kPa; the viscosity of the degassed graphene oxide slurry is 30,000~55,000 mPa·s.

4. The method for preparing a longitudinally high thermal conductivity graphene heat dissipation film according to claim 1, characterized in that, In step S3, the supersaturated metal ion-containing solution is any one of a nitric acid solution, a sulfuric acid solution, and a chloride solution containing metal ions. The metal ions in the supersaturated metal ion-containing solution are any one of copper ions, iron ions, cobalt ions, and nickel ions.

5. The method for preparing a longitudinally high thermal conductivity graphene heat dissipation film according to claim 1, characterized in that, In step S5, the protective atmosphere is an argon atmosphere; the temperature of the graphitization treatment is 2500~2850℃. In step S6, the pressure of the exhaust calendering is not less than 500t, and the total holding time of the exhaust calendering is not less than 12h; the pressure of the dense calendering is not less than 700t, and the holding time of the dense calendering is not less than 30min.

6. The method for preparing a longitudinally high thermal conductivity graphene heat dissipation film according to claim 1, characterized in that, The metallic element is any one of copper, iron, cobalt, and nickel.