Graphene metal composite micro-nano pore structure and preparation method thereof

Abstract

The application provides a graphene metal composite micro-nano-pore structure and a preparation method thereof; the method comprises the following steps: adding graphene oxide into a solvent to obtain graphene oxide slurry; combining the graphene oxide slurry on the surface of a metal substrate to obtain graphene oxide composite metal; using a metal layer and the graphene oxide composite metal to form a graphene oxide composite metal package, and reserving an exhaust port in the graphene oxide composite metal package; and performing the following steps on the graphene oxide composite metal package: first-stage heat treatment to dry the graphene oxide slurry; and second-stage heat treatment to make the graphene oxide foam and expand to fill the metal package shell to obtain the graphene metal composite micro-nano-pore structure. The preparation method is convenient and practical, the graphene metal composite micro-nano-pore structure prepared by the method has a relatively full filling in the metal layer, relatively uniform openings, less impurities, and a relatively complete structure of the metal layer.

Description

Technical Field

[0001] This invention belongs to the field of manufacturing technology of graphene-metal composite micro-nanoporous structures, specifically relating to a graphene-metal composite micro-nanoporous structure and its preparation method. Background Technology

[0002] Graphene is a honeycomb-like planar film formed by carbon atoms in an sp2 hybridization manner. It is a two-dimensional carbon material with a thickness of only one atom layer, possessing excellent electrical, thermal, and mechanical properties, and a high theoretical specific surface area. Porous micro- and nanostructures fabricated using graphene materials can be used in thermal insulation materials, soundproofing and shielding materials, and as a framework for composite materials. However, current graphene micro- and nanopore manufacturing technologies generally suffer from high processing difficulty, high cost, poor environmental friendliness in the production process, and low cell uniformity, making it difficult to meet practical application requirements. Graphene oxide, an important derivative of graphene, has abundant oxygen-containing functional groups such as hydroxyl, carboxyl, epoxy, and carbonyl groups on its surface and edges. These groups undergo decomposition and disproportionation reactions upon heating, generating 6-8 kJ / g of heat, endowing graphene oxide with energetic material properties, and enabling it to spontaneously form a porous structure under certain conditions.

[0003] As an improvement, current methods for preparing graphene microporous foam involve first dispersing graphene, after heat treatment at 800–1500°C in an inert atmosphere, in dimethylformamide, then adding polyurethane granules, stirring to dissolve, coating the mixture, and then subjecting it to air for microphase separation to obtain a polyurethane / graphene composite foam. The polyurethane / graphene composite foam is then heated and carbonized to remove the polyurethane matrix, yielding a graphene microporous foam with a continuous framework structure oriented along the polyurethane pore walls. Similar to this preparation method, most porous graphene is obtained by mixing graphene with easily removable components and then using heat treatment or physical removal. However, micro- and nanoporous structures prepared by such methods generally suffer from poor pore uniformity, low product appearance integrity, and excessive impurities. Furthermore, the preparation process is complex, and some easily removable substances generate large amounts of toxic gases during heat treatment. These problems increase the difficulty of industrializing such technologies and make it difficult to produce products that meet the requirements of downstream applications. Summary of the Invention

[0004] The purpose of this invention is to provide a graphene-metal composite micro-nanoporous structure and its preparation method, so as to solve the problems of poor pore uniformity, poor integrity of finished products and excessive impurities that are common in current micro-nanoporous structures.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing graphene-metal composite micro / nanoporous structures, specifically including the following steps: S1. Add graphene oxide to a solvent and mix to prepare a graphene oxide slurry; wherein the solid content in the graphene oxide slurry is controlled to be 0.1~9%; S2. Graphene oxide slurry is composited onto the surface of a metal substrate to obtain graphene oxide composite metal. S3. A metal encapsulation shell is formed by combining a metal layer with graphene oxide composite metal, thus forming an overall graphene oxide composite metal encapsulation; wherein: the graphene oxide slurry is located inside the metal encapsulation shell; The graphene oxide slurry accounts for 10-50% of the internal volume of the metal packaging shell, and the metal packaging shell is provided with an exhaust port. S4. Perform the following steps on the graphene oxide composite metal encapsulation: First-stage heat treatment to dry the graphene oxide slurry; Second-stage heat treatment to allow the graphene oxide to foam and expand to fill the metal encapsulation shell, thereby obtaining a graphene metal composite micro-nano porous structure.

[0006] In some embodiments, in S1, the solvent includes any one of water, NMP, ethanol, glycerol, and DMF.

[0007] Furthermore, in S1, the solid content in the graphene oxide slurry is controlled to be 5-7%.

[0008] In some embodiments, in S2, the metal substrate and the metal layer include: copper, iron, aluminum, or alloys thereof; The thickness of the metal substrate and the metal layer is controlled to be 100~10000μm.

[0009] Furthermore, in S2, the graphene oxide slurry is coated onto the surface of the metal substrate in any of the following ways: slot coating, cast coating, screen printing, gravure printing, and letterpress printing.

[0010] In some embodiments, in S3, the encapsulation method of the metal layer and the metal substrate includes any one of brazing, arc welding, ultrasonic welding, gas welding, and hot pressing.

[0011] In some embodiments, in S3, the radial dimension of the exhaust port is 3 to 15% of the circumferential dimension of the metal substrate projected along the thickness direction.

[0012] In some embodiments, the heating devices that can be used for both the first-stage heat treatment and the second-stage heat treatment in S4 include: muffle furnace, forced-air oven, vacuum oven, rotary furnace or tube furnace.

[0013] In some implementations, in S4, the parameters of the first-stage heat treatment are controlled as follows: Temperature is controlled at 55~110℃, heating rate is controlled at 0.5~10℃ / min, and time is controlled at 10~90min; The parameters for the second-stage heat treatment are controlled as follows: Temperature is controlled at 90~350℃, heating rate is controlled at 1~10℃ / min, and time is controlled at 50~600min.

[0014] This invention also provides a graphene-metal composite micro / nanoporous structure, comprising a metal substrate encapsulation, wherein the metal substrate encapsulation includes a graphene micro / nanoporous structure, wherein: The metal substrate encapsulation has an exhaust channel, and the graphene micro-nano porous structure has a porous structure.

[0015] Compared with the prior art, the graphene-metal composite micro-nanoporous structure and its preparation method of the present invention have the following beneficial technical effects.

[0016] The present invention discloses a method for preparing a graphene-metal composite micro / nanoporous structure, comprising the following steps: S1, adding graphene oxide to a solvent and mixing to obtain a graphene oxide slurry; wherein the solid content in the graphene oxide slurry is controlled at 0.1-9%; S2, laminating the graphene oxide slurry onto the surface of a metal substrate to obtain a graphene oxide composite metal; S3, using a combination of a metal layer and the graphene oxide composite metal to form a metal encapsulation shell, thereby forming a graphene oxide composite metal encapsulation; wherein the graphene oxide slurry is located inside the metal encapsulation shell; wherein the filling amount of the graphene oxide slurry accounts for 10-50% of the internal volume of the metal encapsulation shell, and the metal encapsulation shell has a reserved vent; S4, subjecting the graphene oxide composite metal encapsulation to: a first-stage heat treatment to dry the graphene oxide slurry; and a second-stage heat treatment to cause the graphene oxide to foam and expand, filling the metal encapsulation shell, thereby obtaining a graphene-metal composite micro / nanoporous structure. Based on the above, the present invention forms a fixed space by laminating a graphene oxide slurry onto a metal surface and then encapsulating the metal. Under specific process conditions, the encapsulated metal is heat-treated to remove the slurry solvent. Utilizing the energetic characteristics of graphene oxide (the oxygen-containing functional groups are gently removed under heating conditions, generating gas that causes the graphene sheets to expand and foam), the slurry expansion rate (slurry filling amount) is controlled to ensure the slurry fills the metal cavity. The uniformity of slurry foaming is improved by controlling the temperature parameters. Ultimately, a graphene micro / nanoporous structure is fabricated.

[0017] This invention, through experimental verification, demonstrates that under the aforementioned solid content conditions, graphene oxide slurry is easy to form and exhibits high coating efficiency, reducing subsequent heat treatment heating time. The invention controls the filling amount of graphene oxide slurry within a certain range of the internal volume of the metal encapsulation shell because, under these conditions, the foaming of the graphene oxide slurry is uniform and controllable, while causing minimal damage to the metal substrate and metal layers.

[0018] In this invention, after a first-stage heat treatment, over 90% of the solvent in the graphene oxide slurry is removed. The remaining solvent helps prevent excessively rapid foaming in the next stage, effectively improving the foaming quality. Building upon this, the invention employs a second-stage heat treatment to allow the graphene oxide to foam and expand, filling the metal encapsulation shell and obtaining a graphene-metal composite micro / nanoporous structure. During this process, the invention utilizes the gentle removal of oxygen-containing functional groups from graphene oxide under specific heating conditions for expansion and foaming, eliminating the need for additional foaming agents. Compared to some existing foaming methods, this invention offers advantages such as high efficiency and better cost control.

[0019] This invention achieves the gentle removal of oxygen-containing functional groups from graphene oxide by controlling the filling ratio of graphene oxide slurry and the heating process, thereby generating gas that causes the graphene sheets to expand and foam without the need for foaming agents, pore-forming agents, or other additives. This solves the problems of poor pore uniformity, damaged finished product appearance, and excessive impurities in existing solutions. The processing is environmentally friendly and has low industrialization difficulty, making it of great practical significance. Attached Figure Description

[0020] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a cross-sectional schematic diagram of the graphene oxide composite metal in the graphene-metal composite micro-nanoporous structure and its preparation method of the present invention. Figure 2 This is a schematic diagram of the metal substrate encapsulation structure in the graphene-metal composite micro-nanoporous structure and its preparation method of the present invention. Figure 3 This is a cross-sectional view of the graphene-metal composite micro-nanoporous structure in Example 3 of the present invention, which describes a graphene-metal composite micro-nanoporous structure and its preparation method. Figure 4 This is a cross-sectional view of the graphene-metal composite micro / nanoporous structure in Example 1 of the present invention, which describes a graphene-metal composite micro / nanoporous structure and its preparation method. Figure 5 This is a cross-sectional view of the graphene-metal composite micro-nanoporous structure in Example 2 of the present invention, which describes a graphene-metal composite micro-nanoporous structure and its preparation method.

[0022] The components include: 1. Metal substrate; 2. Graphene micro-nano porous structure; 3. Exhaust channel; 4. Graphene oxide slurry; and 5. Metal substrate encapsulation. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] How can we achieve good pore uniformity, good finished product appearance integrity, low impurities, environmentally friendly processing, and low industrialization difficulty in graphene-metal composite micro-nano porous structures?

[0026] This invention provides a method for preparing graphene-metal composite micro / nanoporous structures, specifically including the following steps: S1. Add graphene oxide to a solvent and mix to prepare a graphene oxide slurry; wherein the solid content in the graphene oxide slurry is controlled to be 0.1~9%; S2. Graphene oxide slurry is composited onto the surface of a metal substrate to obtain graphene oxide composite metal. S3. A metal encapsulation shell is formed by combining a metal layer with graphene oxide composite metal, thus forming an overall graphene oxide composite metal encapsulation; wherein: the graphene oxide slurry is located inside the metal encapsulation shell; The graphene oxide slurry accounts for 10-50% of the internal volume of the metal packaging shell, and the metal packaging shell is provided with an exhaust port. S4. Perform the following steps on the graphene oxide composite metal encapsulation: First-stage heat treatment to dry the graphene oxide slurry; Second-stage heat treatment to allow the graphene oxide to foam and expand to fill the metal encapsulation shell, thereby obtaining a graphene metal composite micro-nano porous structure. As a preferred embodiment, the amount of graphene oxide slurry in this invention accounts for 25-40% of the internal volume of the metal encapsulation shell.

[0027] This invention ensures that the graphene oxide expands controllably and fully fills the cavity by controlling the ratio of the filling amount of graphene oxide slurry 4 to the volume of the metal substrate 1 cavity. This invention can guarantee uniform pore size, good finished product appearance, and high purity of the micro / nano pore structure without the need for external foaming agents / pore-forming agents (these additives are often difficult to completely remove and will remain in the product cavity, reducing the purity of the pore structure).

[0028] As a preferred embodiment, the solid content in the graphene oxide slurry is controlled at 5-7%. By controlling the solid content in the graphene oxide slurry, this invention makes the graphene oxide slurry easier to form into a paste, resulting in high coating efficiency and reduced heating time for subsequent heat treatment.

[0029] In some embodiments, the metal substrate and metal layer in step 2 include copper, iron, aluminum, or alloys thereof. These metal materials or alloys have high thermal conductivity, structural strength, and weather resistance. Different materials can be selected as needed to achieve the encapsulation and protection of graphene micro- and nanoporous structures.

[0030] Based on this, the thickness of the metal substrate and the metal layer is controlled to be 100~10000μm. Within this thickness range, the graphene oxide produced under the process conditions of this invention can be fully foamed without causing damage to the metal substrate or metal packaging.

[0031] In some embodiments, the solvent in step 1 includes one of water, NMP, ethanol, glycerol, and DMF. In experimental operations, different solvents can be selected according to actual conditions.

[0032] As a preferred embodiment, the amount of graphene oxide slurry in this invention accounts for 25-40% of the internal volume of the metal encapsulation shell. Experimental results show that within this range, the foaming of graphene oxide is more complete, and the metal encapsulation has less interference with the foaming process.

[0033] In some embodiments, the graphene oxide slurry in step 2 is coated onto the surface of the metal substrate by means of: slot coating, cast coating, screen printing, gravure printing, or letterpress printing.

[0034] In this invention, the exhaust channel 3 is not encapsulated, and the radial dimension of the opening of the exhaust channel 3 is controlled to be 3-15% of the projected perimeter of the metal substrate along the thickness direction. This allows the solvent in the graphene oxide slurry to be discharged.

[0035] As a preferred embodiment, the radial dimension of the exhaust channel 3 can be selected to be 3-5% of the projected perimeter of the metal substrate. Within this size range of the exhaust channel 3, the solvent in the graphene oxide slurry can be effectively discharged without damaging the metal substrate or metal encapsulation.

[0036] In some embodiments, the encapsulation method between the metal layer and the metal substrate in step 3 includes brazing, arc welding, ultrasonic welding, gas welding, or hot pressing. This effectively ensures the strength of the metal encapsulation and the airtightness of the product.

[0037] In some embodiments, in step 4, the heating device used for the first-stage heat treatment and the second-stage heat treatment of the present invention can be a muffle furnace, a blower oven, a vacuum oven, a rotary furnace, or a tube furnace.

[0038] In some embodiments, the parameters of the first-stage heat treatment in step 4 are controlled as follows: Under normal atmospheric pressure, the temperature of the first stage heat treatment is controlled at 55~110℃, the heating rate is set at 0.5~10℃ / min, and the heating time is controlled at 10~90min.

[0039] As a preferred embodiment, the highest temperature of the first-stage heat treatment in this invention is 60~95℃, the heating rate is controlled at 0.5~2℃ / min, and the heating time is controlled at 20~60min.

[0040] After the first stage of heat treatment is completed, the product is removed and allowed to cool naturally to room temperature before the second stage of heat treatment can be carried out.

[0041] The parameters for the second-stage heat treatment are controlled as follows: Under normal atmospheric pressure, the temperature of the second-stage heat treatment of this invention is controlled at 90~350℃, the heating rate is controlled at 1~10℃ / min, and the heating time is controlled at 50~600min.

[0042] As a preferred embodiment, the temperature of the second stage heat treatment is controlled at 90~300℃, the heating rate is controlled at 2~5℃ / min, and the heating time is controlled at 150~400min.

[0043] The present invention mainly removes the solvent from the graphene oxide slurry through the first stage of heat treatment, and then uses the second stage of heat treatment to allow the graphene oxide to fully foam and expand, and then fill the metal encapsulation shell to obtain a graphene-metal composite micro-nano porous structure.

[0044] Based on the above, this invention further optimizes the pore size of graphene oxide and improves the integrity of the finished product by controlling the heating rate and the ratio of graphene oxide slurry filling amount to metal matrix cavity volume.

[0045] This invention employs a first-stage heat treatment and a second-stage heat treatment to heat-encapsulate the metal substrate. Utilizing the characteristics of graphene oxide as an energetic material, under the heat treatment conditions of this invention, graphene oxide uniformly self-foams to form a pore structure, eliminating the need for external foaming agents or easily removable pore-forming substances. This simplifies the process, reduces material requirements, and controls costs.

[0046] like Figure 1 and Figure 2 As shown, the graphene-metal composite micro / nanoporous structure of the present invention was prepared based on the above preparation method. Specifically, the present invention encapsulates the metal substrate 1 with a metal layer to form a metal substrate encapsulation 5, wherein the surface of the metal substrate inside has graphene oxide slurry 4. Then, through heat treatment or the like, the internal graphene oxide slurry is foamed to form porous graphene 2.

[0047] Based on the aforementioned preparation method, the graphene-metal composite micro / nanoporous structure of the present invention is prepared, comprising a metal substrate encapsulation 5, wherein the metal substrate encapsulation 5 includes a graphene micro / nanoporous structure 2, wherein: The graphene micro-nanoporous structure 2 prepared by the present invention has a porous structure with relatively uniform openings, and the overall structure has a complete appearance and is basically free of impurities.

[0048] The following specific embodiments further illustrate the graphene-metal composite micro / nanoporous structure and its preparation method according to the present invention: Example 1 Step 1: Disperse graphene oxide in water and mix to prepare a graphene oxide slurry with a solid content of 5%. Step 2: The graphene oxide slurry obtained in Step 1 is coated onto a copper foil with a thickness of 300 μm using a casting method. The copper foil has a size of 30 × 30 cm, the graphene oxide slurry has a coating size of 25 cm × 25 cm, and the coating thickness is 3 mm, thus obtaining a graphene oxide composite copper foil. Step 3: Cover the upper surface of the graphene oxide composite copper foil obtained in Step 2 with a copper foil of 300μm thickness. The copper foil is 35cm×35cm in size, so that the interior of the two copper foils forms an inner cavity of 25cm×25cm with a height of 1cm. A venting channel with an opening length of 5cm is reserved. The area outside the venting channel of the copper foil is welded by laser welding to obtain the composite graphene oxide composite metal. Step 4: Place the composite graphene oxide metal obtained in Step 3 into a forced-air drying oven for the first stage heat treatment from room temperature to 75°C, with a heating rate of 1.5°C / min and a heating time of 60min. Then, use a box furnace for the second stage heat treatment from room temperature to 155°C, with a heating rate of 2°C / min and a heating time of 300min, to obtain the graphene metal composite micro-nano porous structure.

[0049] like Figure 4 As shown, from Figure 4 As can be seen from the cross-sectional image of the graphene-metal composite micro-nanopore, the graphene micro-nanopore structure obtained in Example 1 is fully filled between the copper foils, the micro-nano gap structure between the graphene layers is clear, and the copper foil structure is complete.

[0050] Example 2 Step 1: Disperse graphene oxide in water and mix to prepare a graphene oxide slurry with a solid content of 6%. Step 2: The graphene oxide slurry obtained in Step 1 is coated onto a 500μm thick aluminum foil using a casting method. The aluminum foil has a size of 25×25cm, the graphene oxide slurry has a coating size of 24cm×24cm, and the coating thickness is 3mm, thus obtaining a graphene oxide composite aluminum foil. Step 3: Cover the upper surface of the graphene oxide composite aluminum foil obtained in Step 2 with an aluminum foil of 300μm thickness. The aluminum foil is 25cm×25cm in size, so that the interior of the two aluminum foils forms an inner cavity of 24cm×24cm with a height of 0.8cm. A venting channel with an opening length of 4.5cm is reserved. The area outside the venting channel of the aluminum foil is welded by laser welding to obtain the composite graphene oxide composite metal. Step 4: The composite graphene oxide metal obtained in Step 3 is subjected to a first-stage heat treatment in a muffle furnace from room temperature to 75°C at a heating rate of 1.7°C / min for 45 min. Then, a second-stage heat treatment is performed in a box furnace from room temperature to 250°C at a heating rate of 2.5°C / min for 300 min to obtain a graphene metal composite micro-nano porous structure.

[0051] like Figure 5 As shown, from Figure 5 As can be seen from the cross-sectional diagram of the graphene-metal composite micro-nanopore, the graphene micro-nanopore structure obtained in Example 2 has sufficient filling between the metals and the aluminum foil structure is intact.

[0052] Example 3 Step 1: Disperse graphene oxide in water and mix to prepare a graphene oxide slurry with a solid content of 6%. Step 2: The graphene oxide slurry obtained in Step 1 is coated onto a copper foil with a thickness of 200 μm using a casting method. The copper foil has a size of 10 × 10 cm, the graphene oxide slurry has a coating size of 8 cm × 8 cm, and the coating thickness is 0.8 mm, thus obtaining a graphene oxide composite copper foil. Step 3: Cover the upper surface of the graphene oxide composite copper foil obtained in Step 2 with a copper foil of 200μm thickness. The copper foil is 10cm×10cm in size, so that the interior of the two copper foils forms an 8cm×8cm cavity with a height of 0.2cm. A venting channel with an opening length of 2cm is reserved. The area outside the venting channel of the copper foil is welded by laser welding to obtain the composite graphene oxide composite metal. Step 4: Place the composite graphene oxide metal obtained in Step 3 into a forced-air drying oven for a first-stage heat treatment from room temperature to 75°C, with a heating rate of 1.5°C / min and a heating time of 50min. Then, use a muffle furnace for a second-stage heat treatment from room temperature to 230°C, with a heating rate of 2°C / min and a heating time of 260min, to obtain the graphene metal composite micro-nano porous structure.

[0053] like Figure 3 As shown, from Figure 3 As can be seen from the cross-sectional image of the graphene-metal composite micro-nanopore, the graphene micro-nanopore structure obtained in Example 3 is fully filled, the metal layer structure is complete, and there are no obvious impurities inside.

[0054] In summary, this invention provides a graphene-metal composite micro / nanoporous structure and its preparation method. The graphene-metal composite micro / nanoporous structure prepared by the method of this invention shows improvements in both microstructure and overall appearance. The graphene micro / nanoporous structure of this invention exhibits better pore uniformity, full filling within the metal layer, and a relatively intact metal layer structure with fewer impurities. Furthermore, the preparation process of this invention is convenient, yields a high output, and has certain value for widespread application.

[0055] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene-metal composite micro / nanoporous structure, characterized in that, Specifically, the steps include the following: S1. Add graphene oxide to a solvent and mix to prepare a graphene oxide slurry; wherein the solid content in the graphene oxide slurry is controlled to be 0.1~9%; S2. Graphene oxide slurry is composited onto the surface of a metal substrate to obtain graphene oxide composite metal. S3. Then, the metal layer is combined with the graphene oxide composite metal to form a metal encapsulation shell, and the whole is formed into a graphene oxide composite metal encapsulation; wherein: the graphene oxide slurry is located inside the metal encapsulation shell; The graphene oxide slurry accounts for 10-50% of the internal volume of the metal packaging shell, and the metal packaging shell is provided with an exhaust port. The radial dimension of the exhaust port is 3-15% of the circumferential dimension projected along the thickness direction of the metal substrate; S4. Perform the following steps on the graphene oxide composite metal encapsulation: First-stage heat treatment to dry the graphene oxide slurry; Second-stage heat treatment to allow the graphene oxide to foam and expand to fill the metal encapsulation shell, thereby obtaining a graphene metal composite micro-nano porous structure. The parameters for the first-stage heat treatment are controlled as follows: The temperature is controlled at 55~110℃, the heating rate is controlled at 0.5~10℃ / min, and the heating time is controlled at 10~90min; The parameters for the second-stage heat treatment are controlled as follows: The temperature is controlled at 90~350℃, the heating rate is controlled at 1~10℃ / min, and the heating time is controlled at 50~600min.

2. The method for preparing the graphene-metal composite micro / nanoporous structure according to claim 1, characterized in that, In S1, the solvent includes any one of water, NMP, ethanol, glycerol, and DMF.

3. The method for preparing graphene-metal composite micro / nanoporous structures according to claim 1 or 2, characterized in that, In S1, the solid content in the graphene oxide slurry is controlled to be 5-7%.

4. The method for preparing the graphene-metal composite micro / nanoporous structure according to claim 1, characterized in that, In S2, the metal substrate and the metal layer include: copper, iron, aluminum, or alloys thereof; The thickness of the metal substrate and the metal layer is controlled to be 100~10000μm.

5. The method for preparing the graphene-metal composite micro / nanoporous structure according to claim 4, characterized in that, In S2, the graphene oxide slurry is coated onto the surface of the metal substrate in any one of the following ways: slot coating, cast coating, screen printing, gravure printing, and letterpress printing.

6. The method for preparing the graphene-metal composite micro / nanoporous structure according to claim 1, characterized in that, In S3, the encapsulation method of the metal layer and the metal substrate includes any one of brazing, arc welding, ultrasonic welding, gas welding, and hot pressing.

7. The method for preparing the graphene-metal composite micro / nanoporous structure according to claim 1, characterized in that, In S4, the heating devices used for both the first-stage heat treatment and the second-stage heat treatment include: muffle furnace, blast oven, vacuum oven, rotary furnace or tube furnace.

8. A graphene-metal composite micro / nanoporous structure, characterized in that, The package includes a metal substrate encapsulation (5), wherein the metal substrate encapsulation (5) includes a graphene micro / nanoporous structure (2), wherein: The metal substrate encapsulation (5) has an exhaust channel (3), and the graphene micro-nano pore structure (2) has a porous structure; The graphene-metal composite micro-nanoporous structure is prepared by any one of the preparation methods of graphene-metal composite micro-nanoporous structures according to claims 1-7.

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