CN111978931A - Graphene composite slurry, graphite heat dissipation film structure and preparation method thereof - Google Patents
Graphene composite slurry, graphite heat dissipation film structure and preparation method thereof Download PDFInfo
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- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
- C09K5/08—Materials not undergoing a change of physical state when used
- C09K5/14—Solid materials, e.g. powdery or granular
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- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form
- B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar form; Layered products having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
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- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
- B32B37/10—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the pressing technique, e.g. using action of vacuum or fluid pressure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
- B32B9/005—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile
- B32B9/007—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile comprising carbon, e.g. graphite, composite carbon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
- B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/194—After-treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B2038/0052—Other operations not otherwise provided for
- B32B2038/0088—Expanding, swelling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/30—Properties of the layers or laminate having particular thermal properties
- B32B2307/302—Conductive
Abstract
The graphene composite slurry comprises first-class graphene oxide, second-class graphene oxide, graphene and deionized water, wherein the solid content of the graphene composite slurry is 0.5% -30%; the particle diameter of the first type of graphene oxide is larger than that of the second type of graphene oxide, the first type of graphene oxide has a first type of functional group, the second type of graphene oxide has a second type of functional group, and the first type of functional group and the second type of functional group can be self-assembled into graphene sheets with different sizes. The invention also provides a graphite heat dissipation film structure and a preparation method thereof. The graphite heat dissipation film provided by the invention has the advantages of thicker structure, low manufacturing cost, simple preparation method and high heat conductivity.
Description
Technical Field
The invention relates to the technical field of graphene, in particular to graphene composite slurry, a graphite heat dissipation film structure and a preparation method thereof.
Background
With the rapid development of microelectronic integration technology, high power density electronic devices such as smart phones and tablet computers generate a large amount of heat, and the temperature of the working environment thereof is also increased rapidly, thereby affecting the working performance and the service life of the electronic devices. Particularly, with the coming of the 5G era, the operating power of the solar heat collector is 2.5 times that of 4G, the heat productivity is doubled, and higher requirements are put forward on heat dissipation materials.
The graphite heat dissipation film is a film-shaped material with ultra-high in-plane heat conductivity, and can quickly diffuse heat released by the chip in the plane to realize cooling. However, the current mature graphite heat dissipation film is prepared by carbonizing and graphitizing a Polyimide (PI) film, the method has high requirements on raw materials, and only a thin PI film can obtain an artificial graphite film with high thermal conductivity, so that the product is generally below 25 micrometers, and a thicker graphite film is difficult to obtain. This results in graphite films with insufficient heat flux, difficulty in dissipating more heat, and further limited application, although the thermal conductivity can be as high as 1200W/(mK) or more. Graphene is a unit of graphite material, and graphite material with any thickness can be obtained under certain conditions in theory by assembling, and high heat conductivity is kept, so that the method is a reasonable process for preparing the high-heat-conductivity-coefficient thick film. However, the existing high-thermal-conductivity graphene film is relatively complex in preparation process and relatively high in preparation cost.
Disclosure of Invention
In view of this, the invention provides a graphene composite slurry capable of manufacturing a graphite heat dissipation structure with a relatively thick thickness, a low manufacturing cost, a simple preparation method, and a high thermal conductivity.
It is also necessary to provide a preparation method of the graphite heat dissipation film structure using the graphene composite paste.
It is also necessary to provide a graphite heat dissipation film structure prepared by the method for preparing a graphite heat dissipation film structure as described above.
The graphene composite slurry comprises first-class graphene oxide, second-class graphene oxide, graphene and deionized water, wherein the solid content of the graphene composite slurry is 0.5% -30%; the particle diameter of the first type of graphene oxide is larger than that of the second type of graphene oxide, the first type of graphene oxide has a first type of functional group, the second type of graphene oxide has a second type of functional group, and the first type of functional group and the second type of functional group can be self-assembled into graphene sheets with different sizes.
Further, the graphene composite slurry also comprises carbon nanotubes, and the mass of the carbon nanotubes is 1 per mill-5% of the mass of the graphene material.
Further, the graphene composite slurry also comprises a cosolvent, wherein the mass of the cosolvent is 1 per thousand-5% of the mass of the graphene material.
Further, the graphene composite slurry also comprises a soluble carbon source, wherein the mass of the soluble carbon source is 1 per thousand-5% of the mass of the first type of graphene oxide, the second type of graphene oxide and the graphene.
Further, the soluble carbon source is at least one of polyvinyl alcohol, polyacrylic acid, glucose and polymers thereof.
A preparation method of a graphite heat dissipation film structure comprises the following steps: providing a graphene composite slurry as described above; coating the graphene composite slurry on a first braided fabric; covering a second braided fabric on the first braided fabric coated with the graphene composite slurry, pressurizing and concentrating the graphene composite slurry, and extruding a solvent to reduce the moisture content in the graphene composite slurry to 30% -60%; heating and drying the concentrated graphene composite slurry until the moisture content of the graphene composite slurry is lower than 15%; stripping the first braided fabric and the second braided fabric to obtain a single graphene oxide membrane; stacking and pressing a plurality of single graphene oxide films together to enable the plurality of single graphene oxide films to be integrated to obtain a graphene oxide film structure; reducing the first type of graphene oxide and the second type of graphene oxide in the graphene oxide film structure into graphene to obtain a precursor of a graphite heat dissipation film structure; and graphitizing the precursor of the graphite heat dissipation film structure to obtain the graphite heat dissipation film structure.
Further, after "graphitizing the graphite heat dissipation film structure precursor", the method further comprises: dipping the graphite heat dissipation film structure in a high molecular solution to obtain a graphite/high molecular composite film block; and pressure curing.
Further, before "stacking and pressing a plurality of single graphene oxide films together", the method further includes: and carrying out steam fumigation or water spraying treatment on the graphene oxide membrane to wet the surface of the graphene oxide membrane until a swelling effect is generated.
Further, the drying in the graphene composite slurry after the heating, drying and concentrating is carried out in a drying kiln, the temperature in the drying kiln is 60-95 ℃, and the relative humidity of gas in the drying kiln is 50% -90%.
The graphite heat dissipation film structure is prepared by the preparation method of the graphite heat dissipation film structure.
According to the graphene composite slurry graphite heat dissipation film and the preparation method thereof, the first type and the second type of oxidized graphene and the soluble carbon source which have different particle diameters and have functional groups capable of being self-assembled into graphene sheets with different sizes are used for preparing the graphene composite slurry, the soluble carbon source and the second type of oxidized graphene can fill gaps existing when the first type of graphene is laid flat, so that the defects existing in the first type of graphene are overcome, the second type of functional group of the second type of oxidized graphene and the first type of functional group of the first type of oxidized graphene can be self-assembled into graphene sheets with different sizes with the second type of functional group, so that the cooperation among different materials is realized, and the graphene heat dissipation film with stable structure and performance can be obtained; 2) the carbon nano tubes are added into the graphene composite slurry, so that the overall porosity of the graphite film in the bipolar plate can be increased, a gas inlet and outlet channel is provided for gas generated in the manufacturing process of the graphite heat dissipation film, the heat conduction performance of the bipolar plate can be improved, and an additional heat dissipation assembly is not required to be assembled in a fuel cell, so that the manufacturing cost of the graphite heat dissipation film is reduced; 3) firstly, coating the graphene composite slurry on a woven fabric, and then pressing to filter out a solvent (filter pressing) to further concentrate the graphene composite slurry, so that a thicker graphite heat dissipation film can be obtained, and the cracking of the graphite heat dissipation film caused by too low concentration of the graphene composite slurry and too high drying pressure can be avoided, thereby further reducing the manufacturing cost of the graphite heat dissipation film; 4) the concentrated graphene composite slurry is dried in a drying kiln, so that the gas in the drying kiln keeps high relative humidity, and the problem of cracking of a graphite heat dissipation film caused by too high drying speed can be avoided; 5) the method comprises the following steps of carrying out steam fumigation or water spraying treatment on a plurality of single graphene oxide films before stacking and pressing the graphene oxide films together, so that the surfaces of the graphene oxide films can be wetted to generate a swelling effect, the binding force between two adjacent graphene oxide films can be increased, and a multi-layer graphite heat dissipation film structure can be obtained.
Detailed Description
In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined objects, the following detailed description will be given to specific embodiments, structures, features and effects of the graphene composite paste, the graphite heat dissipation film structure and the preparation method of the graphite heat dissipation film structure provided by the present invention in combination with the preferred embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that when one component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present.
Unless defined otherwise, 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 invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The invention provides graphene composite slurry which comprises a graphene material and deionized water. In the graphene composite slurry, the solid content of the graphene material is 0.5-30%. The graphene material at least comprises a first type of graphene oxide, a second type of graphene oxide and graphene, wherein the particle diameter of the first type of graphene oxide is larger than that of the second type of graphene oxide, the first type of graphene oxide has a first type of functional group, the second type of graphene oxide has a second type of functional group, and the first type of functional group and the second type of functional group can be self-assembled into graphene sheets with intervals.
Wherein the first type of graphene oxide and the second type of graphene oxide can be prepared by different methods.
The second graphene oxide can fill gaps existing in the first graphene oxide when the first graphene oxide is paved, so that defects of the first graphene oxide can be overcome. The first type of functional group and the second type of functional group (hydroxyl or carboxyl and the like) can be self-assembled into graphene sheets with intervals, so that the synergy among different materials is realized, and the graphite heat dissipation film structure with stable structure and performance is further facilitated to be obtained.
The graphene composite slurry further comprises a soluble carbon source, and the mass of the soluble carbon source is 1 per mill-5% of the mass of the graphene material.
The soluble carbon source can provide carbon atoms in the subsequent graphitization process to fill the defects of the graphene and/or the graphene oxide, and the graphite heat dissipation film structure and the bipolar plate with stable structure and performance can be obtained. If the content of the soluble carbon source exceeds 5%, non-graphite-structured carbon atoms may be generated during the graphitization process, which may be detrimental to the performance of the graphite heat dissipation film structure and the bipolar plate. If the content of the soluble carbon source is less than 1 per thousand, carbon can be automatically rearranged in the graphitization process, the soluble carbon source cannot provide enough carbon atoms, and the performance of the graphite heat dissipation film structure and the bipolar plate is not greatly influenced.
Wherein the soluble carbon source is at least one of polyvinyl alcohol, polyacrylic acid, glucose and polymers thereof.
The graphene composite slurry further comprises carbon nanotubes, and the mass of each carbon nanotube is 1 per thousand-5% of that of the graphene material.
The small amount of carbon nano tubes can increase the overall porosity of the graphite heat dissipation film in the graphite heat dissipation film structure, provide a passage for gas generated in the manufacturing process of the graphite heat dissipation film structure to enter and exit, improve the heat conduction performance of the graphite heat dissipation film structure and the bipolar plate, and avoid assembling additional heat dissipation components in a fuel cell, thereby reducing the manufacturing cost of the graphite heat dissipation film structure and the bipolar plate.
In addition, a small amount of the carbon nanotubes can balance the performance and manufacturing cost of the graphite heat dissipation film structure. If the content of the carbon nanotubes exceeds 5%, the carbon nanotubes affect the density of the graphite heat dissipation film structure. If the content of the carbon nano tube is less than 1 per thousand, the effect of increasing the porosity is not achieved.
The graphene composite slurry further comprises a cosolvent, and the mass of the cosolvent is 1 per mill-5% of the mass of the graphene material.
Wherein the cosolvent comprises at least one of ethanol, propanol, butanol, isopropanol, acetone and the like.
The invention also provides a preparation method of the graphite heat dissipation film structure, which comprises the following steps:
step S11: providing the graphene composite slurry as described above.
Step S12: coating the graphene composite slurry on a first braided fabric; covering a second braided fabric on the first braided fabric coated with the graphene composite slurry; pressurizing and concentrating the graphene composite slurry, and extruding a solvent to reduce the water content in the graphene composite slurry to 30% -60%; heating and drying the concentrated graphene composite slurry until the moisture content of the graphene composite slurry is lower than 15%; and stripping the first braided fabric and the second braided fabric to obtain a single graphene oxide membrane.
Step S13: and stacking and pressing a plurality of single graphene oxide films together to integrate the plurality of single graphene oxide films into a whole, thereby obtaining the graphene oxide film structure.
Step S14: and reducing the first type of graphene oxide and the second type of graphene oxide in the graphene oxide film structure into graphene to obtain a precursor of the graphite heat dissipation film structure.
Step S15: and graphitizing the precursor of the graphite heat dissipation film structure to obtain the graphite heat dissipation film structure.
After the step S15, the method further includes a step S16: dipping the graphite heat dissipation film structure in a high molecular solution to obtain a graphite/high molecular composite film block; and pressurizing and curing to obtain the graphite heat dissipation film structure.
Wherein, after the step S6, the method further includes a step S17 of polishing or grinding the graphite heat dissipation film structure.
In step S12, the drying in the "graphene composite slurry after heating, drying and concentrating" is performed in a drying kiln, the temperature in the drying kiln is 60 to 95 ℃, and the relative humidity of the gas in the drying kiln is 50 to 90%. And the higher humidity is kept, so that the graphene oxide film can be prevented from cracking due to the overhigh drying speed.
In step S12, the coating thickness of the graphene composite slurry is 0.5-20 mm, the coating of the graphene composite slurry is completed by a tape casting process, and the graphene composite slurry sequentially passes through a plurality of scrapers with different heights, so that the uniformity of the coating thickness is guaranteed, and the orientation degree of graphene in the graphene composite slurry is improved.
In step S12, the first knitted fabric and the second knitted fabric are nonwoven fabrics made of nanofibers obtained by spinning or fabrics knitted with chemical fiber materials. The main components of the non-woven fabric are high polymer materials such as polyimide, polyacrylonitrile and the like. The porosity of the first braided fabric and the porosity of the second braided fabric are 30-90%, and the diameter of a gap of the first braided fabric and the second braided fabric is smaller than 1 mm.
Wherein, in step S12, the first woven fabric and the second woven fabric are washed and reused after being stripped.
Before step S13, the method further includes the steps of: and (3) carrying out steam fumigation or water spraying treatment on the graphene oxide film, and also coating a small amount of graphene slurry again to ensure that the surface of the graphene oxide film is wetted to generate a swelling effect so as to improve the binding force of the graphene oxide film during pressing.
In step S13, the phrase "stacking and laminating a plurality of single graphene oxide films" refers to a process in which 2 to 10 graphene oxide films are laminated under pressure, and may be continuously rolled or intermittently flat-pressed. Of course, the number of the graphene oxide films stacked together may also be more than 10, which may be determined according to actual circumstances.
Wherein, in step S13, the graphene oxide film structure (formed by stacking multiple graphene films) has a thickness of 5-20mm before lamination.
In step 14, the reduction may be performed by thermal reduction, chemical reduction, electrochemical reduction, or the like. In this embodiment, the reduction is a thermal reduction method. The thermal reduction is to heat the mixture to 800 ℃ at the speed of 0.2-5 ℃ per minute under the condition of 15000Pa for 5000-. Wherein, a slow heating speed is adopted between 120 ℃ and 160 ℃, and the speed is not more than 2 ℃ per minute.
In step S15, the graphitization is performed in an inner-series graphitization furnace, and the reduced graphite heat dissipation film structure precursor is placed around an inner-series motor and is heated by energization of electrodes, so as to achieve the graphitization purpose. Wherein the pressure of the graphitization is 1x104-3x105Pa, and the graphitization temperature is more than 3000 ℃.
In step S16, the polymer solution is impregnated to reduce the gas permeability of the graphite heat dissipation film structure. The polymer solution needs to satisfy the following conditions: the viscosity is relatively low, the solvent is relatively quick to dry, the solvent is cheap and safe, and after the high-molecular material in the high-molecular solution is subjected to pressure curing, the high-molecular material in the high-molecular solution must be capable of being crosslinked, so that the high-molecular material is changed from soluble to insoluble.
In step S16, pressure curing is performed in a specific mold. The pressurization is used for increasing the density of the graphite heat dissipation film structure and ensuring that the graphite heat dissipation film structure is airtight. The curing is to change the high molecular weight material from soluble to insoluble. The specific mold is internally provided with a pattern consistent with the surface of the graphite heat dissipation film structure so as to avoid damaging the graphite heat dissipation film structure.
The invention also provides a graphite heat dissipation film structure prepared by the preparation method of the graphite heat dissipation film structure. The graphite heat dissipation film structure comprises at least one graphite heat dissipation film layer. If the graphite heat dissipation film structure comprises at least two graphite heat dissipation film layers, the at least two graphite heat dissipation film layers are tightly laminated into a whole.
The graphite heat dissipation film structure provided by the invention can be used in the fields of heat equalizing films, heating films, heat dissipation blocks, bipolar plates and the like.
The following examples are provided to specifically describe the method for preparing the graphite heat dissipation film structure of the present invention.
Example 1
Preparing graphene composite slurry: the composite slurry is prepared by mixing, fully stirring and dispersing 5% of graphene oxide (wherein 4% of graphene oxide has a sheet diameter of 20 micrometers, 0.8% of graphene oxide has a sheet diameter of 10 micrometers, and 0.2% of graphene oxide has a sheet diameter of 2 micrometers), 1% of graphene oxide, 0.3% of glucose, 2% of ethanol and the balance of deionized water.
Preparing a single-layer graphene oxide film: pouring the prepared composite slurry into a die with a braided fabric at the bottom and a metal frame at the periphery, and coating the composite slurry smoothly, wherein the thickness of the whole slurry is 10 mm; covering a layer of fabric with the same bottom on the surface, applying pressure on the upper layer of fabric by a pressure head with the size matched with that of the metal frame on the top, enabling the aqueous solvent in the sizing agent to flow out from the pores of the lower layer of fabric along with the increase of the pressure until the overall thickness is reduced to 1/2, enabling the thickness of the sizing agent to be 5mm, then removing the pressure, placing the whole in a drying kiln with the temperature of 80 ℃ and the humidity of 85%, and drying until the fabric can be naturally stripped from the graphene oxide film, thereby obtaining the dried single graphene oxide film.
Preparing a graphene oxide film structure: and (2) placing the obtained single graphene oxide films in a closed container for steam fumigation or water spraying treatment to wet the surfaces of the graphene oxide composite film blocks until a swelling effect is generated, stacking the multiple film blocks, and applying a certain pressure, wherein the multilayer film blocks can be pressed into a whole due to the swelling effect generated by the graphene oxide on the surfaces of the film blocks, so that the graphene oxide film structure is obtained.
Preparing a graphite heat dissipation film structure: and (3) placing the graphene oxide film structure in a graphite mold for graphitization, applying pressure of 5000Pa, heating to 800 ℃ at the speed of 2 ℃/min in a vacuum state, then preserving heat for 2h, and naturally cooling to normal temperature to complete thermal reduction treatment of the graphene oxide. And increasing the pressure to 30000Pa, assembling the graphite mold around the inner-series graphitization furnace, electrifying the electrodes to generate heat at a temperature of over 3000 ℃ to realize graphitization, and naturally cooling to room temperature along with the furnace. The graphite film after being taken out of the furnace is compacted by a tablet machine and rolling to reach the density of more than 1.8g/ml, and the high heat-conducting film product is formed by shaping and trimming. According to different layers, the material with the thickness of 20-500 microns can be obtained. The heat conductivity coefficient of the graphite heat dissipation film structure is measured, and the heat conductivity coefficient can reach more than 1000W/(mK).
Example 2
Preparing graphene composite slurry: the composite slurry is prepared by mixing, fully stirring and dispersing 10% of graphene oxide (wherein 6% of graphene oxide has a sheet diameter of 20 micrometers, 3% of graphene oxide has a sheet diameter of 10 micrometers, and 1% of graphene oxide has a sheet diameter of 2 micrometers), 1% of graphene oxide has a glucose content of 0.45%, 2.5% of ethanol and 86.05% of deionized water.
Preparing a single-layer graphene oxide film: the same method as that of example 1 for preparing a single-layer graphene oxide film.
Preparing a graphene oxide film structure: the same method as that of example 1 for preparing the graphene oxide film structure.
Preparing a graphite heat dissipation film: the same procedure as in example 1 was used to prepare a graphite heat-dissipating film. The heat conductivity coefficient of the graphite heat dissipation film can reach over 900W/(mK) through measurement.
Example 3
Preparing graphene composite slurry: the composite slurry is prepared by mixing, fully stirring and dispersing 10% of graphene oxide (wherein 6% of graphene is 20 micrometers in sheet diameter, 3% of graphene is 10 micrometers in sheet diameter, and 1% of graphene is 2 micrometers in sheet diameter), 1% of graphene, 0.45% of glucose, 0.5% of carbon nanotubes, 2.5% of ethanol and 85.55% of deionized water.
Preparing a single-layer graphene oxide film: the same method as that of example 1 for preparing a single-layer graphene oxide film.
Preparing a graphene oxide film structure: the same method as that of example 1 for preparing the graphene oxide film structure.
Preparing a graphite heat dissipation film: the density can reach 1.7g/ml, which is the same as the method for preparing the graphite heat dissipation film in the example 1. The heat conductivity coefficient of the graphite heat dissipation film can reach over 900W/(mK) through measurement.
From the above, the graphene oxide + graphene + soluble carbon source is used as a raw material, and the bulk graphite heat dissipation film with high heat conductivity can be obtained through the self-assembly effect of the nano material (carbon nano tube), wherein the heat conductivity of the bulk graphite heat dissipation film is more than 2 times that of the bulk graphite heat dissipation film formed by pressing expanded graphite.
According to the preparation method of the graphene composite slurry, the bipolar plate and the bipolar plate, the first graphene oxide and the second graphene oxide which have different particle diameters and have functional groups capable of being self-assembled into graphene sheets with different sizes and a soluble carbon source and the like are used for preparing the graphene composite slurry, the soluble carbon source and the second graphene oxide can fill gaps existing when the first graphene is laid flat, so that the defects of the first graphene are overcome, the second functional group of the second graphene oxide and the first functional group of the first graphene oxide can be self-assembled into graphene sheets with different sizes and intervals with the second functional group, so that the cooperation among different materials is realized, and the graphene heat dissipation film with stable structure and performance can be obtained; 2) the carbon nano tubes are added into the graphene composite slurry, so that the overall porosity of the graphite film in the bipolar plate can be increased, a gas inlet and outlet channel is provided for gas generated in the manufacturing process of the graphite heat dissipation film, the heat conduction performance of the bipolar plate can be improved, and an additional heat dissipation assembly is not required to be assembled in a fuel cell, so that the manufacturing cost of the graphite heat dissipation film is reduced; 3) firstly, coating the graphene composite slurry on a woven fabric, and then pressing to filter out a solvent (filter pressing) to further concentrate the graphene composite slurry, so that a thicker graphite heat dissipation film can be obtained, and the cracking of the graphite heat dissipation film caused by too low concentration of the graphene composite slurry and too high drying pressure can be avoided, thereby further reducing the manufacturing cost of the graphite heat dissipation film; 4) the concentrated graphene composite slurry is dried in a drying kiln, so that the gas in the drying kiln keeps high relative humidity, and the problem of cracking of a graphite heat dissipation film caused by too high drying speed can be avoided; 5) the method comprises the following steps of carrying out steam fumigation or water spraying treatment on a plurality of single graphene oxide films before stacking and pressing the graphene oxide films together, so that the surfaces of the graphene oxide films can be wetted to generate a swelling effect, the binding force between two adjacent graphene oxide films can be increased, and a multi-layer graphite heat dissipation film structure can be obtained.
Although the present invention has been described with reference to the above preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. The graphene composite slurry is characterized by comprising a first type of graphene oxide, a second type of graphene oxide, graphene and deionized water, wherein the solid content of the graphene composite slurry is 0.5% -30%; the particle diameter of the first type of graphene oxide is larger than that of the second type of graphene oxide, the first type of graphene oxide has a first type of functional group, the second type of graphene oxide has a second type of functional group, and the first type of functional group and the second type of functional group can be self-assembled into graphene sheets with different sizes.
2. The graphene composite paste according to claim 1, wherein the graphene composite paste further comprises carbon nanotubes, and the mass of the carbon nanotubes is 1% to 5% of the mass of the graphene material.
3. The graphene composite paste according to claim 2, further comprising a cosolvent, wherein the cosolvent is 1% to 5% by mass of the graphene material.
4. The graphene composite paste according to claim 3, further comprising a soluble carbon source, wherein the mass of the soluble carbon source is 1% o to 5% of the mass of the first type of graphene oxide, the second type of graphene oxide, and the graphene.
5. The graphene composite paste according to claim 4, wherein the soluble carbon source is at least one of polyvinyl alcohol, polyacrylic acid, glucose, and polymers thereof.
6. A preparation method of a graphite heat dissipation film structure is characterized by comprising the following steps:
providing the graphene composite paste according to any one of claims 1 to 5;
coating the graphene composite slurry on a first braided fabric; covering a second braided fabric on the first braided fabric coated with the graphene composite slurry, pressurizing and concentrating the graphene composite slurry, and extruding a solvent to reduce the moisture content in the graphene composite slurry to 30% -60%; heating and drying the concentrated graphene composite slurry until the moisture content of the graphene composite slurry is lower than 15%; stripping the first braided fabric and the second braided fabric to obtain a single graphene oxide membrane;
stacking and pressing a plurality of single graphene oxide films together to enable the plurality of single graphene oxide films to be integrated to obtain a graphene oxide film structure;
reducing the first type of graphene oxide and the second type of graphene oxide in the graphene oxide film structure into graphene to obtain a precursor of a graphite heat dissipation film structure; and
and graphitizing the precursor of the graphite heat dissipation film structure to obtain the graphite heat dissipation film structure.
7. The method for preparing a graphite heat-dissipating film structure according to claim 6, further comprising, after graphitizing the graphite heat-dissipating film structure precursor:
dipping the graphite heat dissipation film structure in a high molecular solution to obtain a graphite/high molecular composite film block; and
and (5) pressing and curing.
8. The method for preparing a graphite heat-dissipating film structure according to claim 6, further comprising, before "stacking and pressing a plurality of single graphene oxide films together:
and carrying out steam fumigation or water spraying treatment on the graphene oxide membrane to wet the surface of the graphene oxide membrane until a swelling effect is generated.
9. The method for preparing the graphite heat dissipation film structure as recited in claim 6, wherein the drying of the concentrated graphene composite slurry by heating is performed in a drying kiln, the temperature in the drying kiln is 60-95 ℃, and the relative humidity of the gas in the drying kiln is 50-90%.
10. A graphite heat dissipation film structure, characterized in that the graphite heat dissipation film structure is prepared by the method for preparing the graphite heat dissipation film structure of any one of claims 6 to 9.
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