A multi-scale structure graphene macroscopic body, a preparation method thereof and application thereof as an electromagnetic shielding material

Abstract

The present application relates to a kind of preparation methods of multi-scale structure graphene macroscopic body, the preparation method includes the following steps: (1) using chemical oxidation method to prepare the few exfoliation layer graphene oxide, obtain graphene oxide water dispersion liquid;(2) adding surfactant to the graphene oxide water dispersion liquid in step (1), stirring to obtain bubble group filled graphene oxide slurry, i.e.printable foaming slurry;(3) the foaming slurry of step (2) is loaded into syringe and is directly written printing, obtain specific shape three-dimensional macroscopic body;(4) the three-dimensional macroscopic body of step (3) is dry formed and reduction treatment, obtain multi-scale structure graphene macroscopic body.The multi-scale structure graphene macroscopic body prepared in the present application, with personalized customization, ultra-low density, super-elasticity and excellent electromagnetic shielding performance, is a kind of electromagnetic shielding material with good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic shielding materials, and particularly relates to a multi-scale structure graphene macroscopic body, a preparation method thereof and application thereof as an electromagnetic shielding material. BACKGROUND

[0002] The rapid development of modern electronic information technology improves people's quality of life, but at the same time, the influence of electromagnetic interference and radiation pollution on the operation of electronic devices, human life and health is also increasingly significant. Developing a lightweight, strong and excellent performance electromagnetic shielding material is an important means to alleviate harmful electromagnetic radiation pollution. With the continuous development of portable and implantable devices, new requirements for the self-defined customization of the structure of electromagnetic shielding materials are put forward. Graphene macroscopic body, due to its ultra-low density, rich porosity, large specific surface area, high electrical conductivity, high thermal and chemical stability, and excellent electromagnetic shielding performance, is a kind of electromagnetic shielding material with good application prospect. However, similar to other conventional electromagnetic shielding materials (such as one-dimensional carbon nanotubes and two-dimensional MXene), although graphene macroscopic body has excellent electromagnetic shielding capacity, due to the poor processability of the material, it is difficult to realize controllable customization by using conventional graphene powder or aqueous dispersion, thus it is difficult to meet the individualized customization demand of different electronic devices for the shape of shielding materials. This largely limits the development and application of electromagnetic shielding materials.

[0003] Direct ink writing printing is a technology that uses electromagnetic shielding material powder and thickening agent to prepare viscoelastic ink, and prints three-dimensional macroscopic bodies by layer-by-layer stacking accumulation method. It can manufacture complex, fine and personalized structural devices that are difficult to manufacture by traditional processing methods, and realize one-step forming from materials to devices. Obtaining shielding material slurry or precursor with certain viscosity and rheological property is the key to realize direct writing printing of three-dimensional electromagnetic shielding material macroscopic bodies. In order to improve the rheological property of electromagnetic shielding material slurry, supplement and enhance the viscosity of the material, and obtain excellent printability, the content of electromagnetic shielding material in the slurry is usually increased or various fillers are introduced to give the electromagnetic shielding material slurry printability. For example, to improve the rheological property of MXene slurry, the content of MXene is increased to 28.9wt%(Orangi, et al. ACS Nano 2020, 14, 640-650); cellulose is used as a functional filler and added to graphene oxide slurry(1.7wt%) to improve the viscosity and rheological property of the shielding material slurry, realize continuous extrusion of the slurry, and improve the stability of the printed three-dimensional structure(Erfanian, et al. Carbon 2023, 210, 118037); or high concentration shielding powder(15-30wt% carbon nanotubes, graphene nanosheets, metal wires, etc.) and high concentration filler(65-84wt% polymer) are used to realize direct writing printing of three-dimensional electromagnetic shielding materials(CN113561473B). However, improving the rheological property of electromagnetic shielding slurry by the above methods will inevitably lead to high density and hard structure of the final printed electromagnetic shielding material macroscopic body, and the introduction of fillers will adversely affect the mechanical and electrical properties of the material. In addition, the existing methods only focus on improving the rheological property of electromagnetic shielding slurry, preparing stable printable ink, and realizing the individual customization of the macroscopic shape of three-dimensional electromagnetic shielding materials, but there is little report on the design of the microstructure of the material. The performance of the material is always determined by the microstructure. Under the premise of realizing the individual customization of the macroscopic structure of electromagnetic shielding materials, designing and controlling the microstructure of the material is of great significance and application value for realizing customized electromagnetic shielding materials with excellent performance. It is still a great challenge to use direct writing printing to realize lightweight and strong three-dimensional electromagnetic shielding macroscopic bodies, and to realize the controllable design of the macroscopic and microstructure of electromagnetic shielding materials, and to build electromagnetic shielding devices with excellent comprehensive performance.

[0004] The present application introduces bubble groups into the slurry by foaming strategy to improve the viscosity and rheology of the electromagnetic shielding material slurry, combines with direct writing printing technology, designs lightweight porous graphene macroscopic body with specific macroscopic shape, and realizes controllable regulation of the microstructure of the printed graphene macroscopic body by taking the bubble groups as templates. On the one hand, the introduction of the bubble groups forms a large number of gas-liquid interfaces in the slurry, uniformly traps the nanosheet layers in the film between the gas-liquid interfaces, thereby limiting the movement of the nanosheet layers and improving the rheology of the slurry; on the other hand, the bubble groups act as templates for the self-assembly of the nanosheet layers, guide the crosslinking of the nanosheet layers in the film at the gas-liquid interfaces, inhibit the face-to-face stacking of the nanosheet layers, build a spherical closed porous structure wrapped by a small number of nanosheet layers, increase the passing path and reflection interface of the electromagnetic waves in the graphene macroscopic body, and strengthen the capture, interference and attenuation of the incident electromagnetic waves, thereby simultaneously improving the total electromagnetic shielding performance and the proportion of absorbed electromagnetic waves. At present, there is no report on the preparation of graphene electromagnetic shielding macroscopic body with multi-scale macrostructure and microstructure by introducing bubble groups and combining 3D printing technology. SUMMARY

[0005] The present application aims to solve the key problems existing in the preparation technology of the existing electromagnetic shielding materials, and provides a preparation method of graphene macroscopic body with multi-scale structure and electromagnetic shielding material. The method only uses bubble groups to adjust the rheology of graphene oxide water dispersion, realizes direct writing printing of low-concentration graphene oxide slurry without adding any filler, provides a bubble template for the self-assembly of nanosheet layers, guides the ordered arrangement of two-dimensional nanosheet layers, inhibits the stacking of nanosheet layers, builds a spherical closed porous structure wrapped by a small number of nanosheet layers, fully plays the reflection and dissipation effect of nanosheet layers on electromagnetic waves, and strengthens the interference and attenuation of electromagnetic waves in the material.

[0006] One of the purposes of the present application is to provide a preparation method of graphene macroscopic body with multi-scale structure, characterized by comprising the following steps:

[0007] Obtaining of graphene oxide dispersion: preparing exfoliated few-layer graphene oxide by chemical oxidation method to obtain graphene oxide water dispersion as initial slurry;

[0008] Obtaining of printable foaming ink: adding a surfactant to the graphene oxide water dispersion, stirring to obtain a graphene oxide slurry filled with bubble groups, obtaining foaming slurry, i.e. printable foaming ink;

[0009] Obtaining of three-dimensional macroscopic body with specific shape by direct writing printing: loading the obtained foaming slurry into a syringe with a needle, continuously and smoothly extruding the slurry onto a low-temperature aluminum plate to perform direct writing printing, and obtaining a three-dimensional macroscopic body with specific shape;

[0010] Obtaining of the multi-scale structure graphene macroscopic body: placing the obtained three-dimensional macroscopic body in a refrigerator at-20℃ for 30 minutes, then drying and shaping, removing the internal ice crystals, preferably drying for 24-48 hours, then carrying out high-temperature heat treatment or chemical reduction under the protection of an inert atmosphere, and finally obtaining the 3D-printed multi-scale structure graphene macroscopic body.

[0011] Further, in the obtaining step of the graphene oxide dispersion liquid, the graphene oxide in the graphene oxide aqueous solution is obtained by a chemical oxidation method including a Hummers method, a modified Hummers method, a Brodie method, and a Staudenmaier method;

[0012] Preferably, the concentration of the graphene oxide aqueous solution is 0.5wt%-2wt%;

[0013] Further, in the obtaining step of the printable foaming ink, the added surfactant is any one of an alkyl glycoside, sodium dodecyl benzene sulfonate, and stearic acid;

[0014] Preferably, the mass ratio of the surfactant to graphene oxide is 1:2-2:1;

[0015] Further, in the obtaining step of the printable foaming ink, cellulose, polyethylene glycol, or polyvinyl alcohol, etc. can be added as a foam stabilizer to improve the stability of the foaming ink at room temperature;

[0016] Further, in the obtaining step of the printable foaming ink, the stirring method includes any one or a combination of mechanical stirring, magnetic stirring, and vortex oscillation;

[0017] Preferably, the stirring is mechanical stirring, the stirring rate is 500-5000 revolutions per minute, and the stirring time is 2-10 minutes; further preferably, the mechanical stirring rate is 1000-3000 revolutions per minute, and the stirring time is 4-6 minutes;

[0018] Further, in the obtaining step of the directly written and printed three-dimensional macroscopic body of a specific shape, the inner diameter of the needle of the syringe is 200-1000μm, the extrusion printing moving speed is 1-10mm / s, the extrusion pressure is 30-300kPa, and the surface temperature of the aluminum plate is-10-0℃;

[0019] Further, in the obtaining step of the multi-scale structure graphene macroscopic body, the drying and shaping method includes vacuum freeze drying and CO2 supercritical drying;

[0020] Further, in the obtaining step of the multi-scale structure graphene macroscopic body, the reduction method includes any one of thermal reduction and chemical reduction;

[0021] Preferably, the temperature of the thermal reduction treatment is 400-1500 DEG C, the heat treatment time is 20-120 minutes, the temperature rising rate is 5-30 DEG C / min, and the inert gas protection includes nitrogen atmosphere and argon atmosphere; further preferably, the temperature of the high-temperature heat treatment is 500-1000 DEG C, and the heat treatment time is 20-60 minutes;

[0022] The second object of the present application is to provide a multi-scale structure graphene macrobody, which is prepared by the method of the first object, and is characterized by individualized customization of macroscopic shape, ultralow density, ultrahigh elasticity, and ordered assembly of nanosheet layers to form a regular few-sheeter wrapped spherical closed porous structure.

[0023] The third object of the present application is to provide an electromagnetic shielding material, which is a multi-scale structure graphene macrobody prepared by the method of the first object.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] The present application uses graphene oxide water dispersion as initial slurry, introduces bubble groups by stirring method, improves the viscoelasticity of graphene oxide water dispersion, prepares printable graphene oxide foaming ink, realizes 3D printing of specific shape macrostructure, simultaneously uses bubble groups as templates to guide ordered self-assembly of nanosheet layers, and constructs few-sheeter wrapped spherical closed porous network structure, and finally obtains 3D printed multi-scale structure graphene macrobody through drying and reduction treatment.

[0026] (1) Rapid customization printing

[0027] The graphene oxide foaming ink provided by the present application only uses the number of bubble groups to adjust the viscoelasticity thereof, and the viscosity range can be controlled in 1-2000 Pa·s, and has excellent rheological properties and room temperature stability.

[0028] The method can play the function of preparing the material without removing the filler.

[0029] (2) Ultra-low density

[0030] The preparation method directly uses the bubble group as a viscosity regulator, does not need to increase the content of functional materials or add additional fillers, greatly reduces the use amount of materials, constructs a rich porous structure in the material by using the bubble group as a template, further reduces the density of the electromagnetic shielding material, and therefore the obtained graphene electromagnetic shielding macroscopic body presents an ultra-low density characteristic, and the density is only 0.001-0.010 g / cm 3 .

[0031] (3) Ultra-strong elasticity

[0032] Through test verification, the multi-scale structure graphene electromagnetic shielding macroscopic body obtained by the preparation method can maintain a good structure after 1000 compression cycle tests, and can immediately (within 1 s) recover to the original height after the external force is removed.

[0033] (4) Excellent electromagnetic shielding performance

[0034] The multi-scale structure graphene electromagnetic shielding macroscopic body obtained by the preparation method has an electromagnetic shielding performance of up to 103.2 dB when the thickness is 1 cm, and the surface reflection is only 4.8 dB. When the thickness and density of the shielding material are comprehensively considered, the specific electromagnetic shielding performance can be up to 52252 dB·cm 2 / g, which is the largest value among the reported foam materials. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a macroscopic morphology diagram of the 3D printed multi-scale structure graphene electromagnetic shielding macroscopic body prepared in Example 1.

[0036] Figure 2 It is a scanning electron microscope diagram of the multi-scale structure graphene electromagnetic shielding macroscopic body prepared in Example 1.

[0037] Figure 3 It is a scanning electron microscope diagram of the conventional graphene macroscopic body prepared in Comparative Example 1.

[0038] Figure 4 It is a cyclic compression test diagram of the multi-scale structure graphene electromagnetic shielding macroscopic body in Example 1.

[0039] Figure 5 It is a cyclic compression test diagram of the conventional graphene macroscopic body prepared in Comparative Example 1.

[0040] Figure 6A comparison chart of electromagnetic shielding performance of graphene macrobodies prepared in Examples 1-3 and Comparative Example 1. DETAILED DESCRIPTION

[0041] Embodiments of the present application are described in detail below with reference to examples illustrated in the accompanying drawings, in which the same or similar components have the same or similar designations throughout the various figures and like reference numerals have been used, where possible, to designate identical or like components that are common to the figures. The embodiments described below are illustrative of the present application and are not meant to be limiting of the application. Unless otherwise indicated, the description of the embodiments is intended to apply equally to all aspects of the present application. The examples set forth herein are intended to be illustrative, not limiting. Descriptions of the techniques and conditions of the various synthetic procedures and measurements utilized herein are presented in the Examples below. The reagents or instruments used are not specified by manufacturer unless otherwise indicated.

[0042] Example 1

[0043] Step 1: Exfoliated few-layer graphene oxide was prepared by a conventional modified Hummers chemical oxidation method, and a graphene oxide aqueous dispersion with a concentration of 0.8 wt% was obtained by dialysis purification;

[0044] Step 2: 60 mL of the graphene oxide aqueous dispersion in Step 1 was taken, 0.45 g of alkyl glycoside was added, and a large number of bubbles were introduced by mechanical stirring at a rate of 2000 rpm for 5 min to obtain a bubble group-filled graphene oxide slurry, i.e., a printable foaming ink;

[0045] Step 3: The graphene oxide foaming slurry in Step 2 was loaded into a syringe with a needle, the inner diameter of the needle was 400 μm, then the syringe was fixed on an operation table, the moving rate and the extrusion pressure were set to 4 mm / s and 140 kPa, the ink was continuously and smoothly extruded onto a low-temperature aluminum plate, the surface temperature of the aluminum plate was set to -4°C, and the layer-by-layer printing of the ink direct writing was performed to prepare a specific grid-shaped three-dimensional macrobody;

[0046] Step 4: The three-dimensional grid-shaped macrobody in Step 3 was placed in a -20°C refrigerator for 30 min, then freeze-dried to form, remove the internal ice crystals, freeze-dried for 24 hours, and then heat-treated at 500°C for 1 hour under the protection of argon atmosphere, the temperature rising rate was 20°C / min, and finally a 3D-printed multi-scale structure graphene macrobody was obtained.

[0047] The obtained graphene oxide foaming slurry had a viscosity of up to 1500 Pa·s, and its viscosity and rheological properties were significantly improved, showing non-Newtonian fluid characteristics; the density of the obtained 3D-printed multi-scale structure graphene electromagnetic shielding macrobody was 0.0045 g / cm 3 (<0.01 g / cm 3, i.e. super light structure); the conductivity can reach 36.9 S / m; after 1000 compression cycle tests, it can still maintain its good structure and can rebound to the original height immediately (within 1 second) after the external force is removed, and when the compression amount is 90%, the compression modulus reaches 78.3 kPa; when the thickness is 0.6 cm, the total electromagnetic shielding performance can reach 76.4 dB, of which the surface reflection is 4.5 dB and the internal absorption is 70.9 dB.

[0048] Example 2

[0049] The difference between this example and Example 1 is only that the mechanical stirring rate in step 2 is increased to 3000 rpm, and the rest is the same, i.e. a 3D printed multi-scale structure graphene electromagnetic shielding macro body with super light, super strong elasticity and high electromagnetic shielding performance is obtained.

[0050] The viscosity and rheological properties of the obtained graphene oxide foaming slurry are improved and exhibit non-Newtonian fluid characteristics; the density of the obtained multi-scale structure graphene electromagnetic shielding macro body is only 0.0033 g / cm 3 ; the conductivity is 23.2 S / m; it exhibits more excellent rebound performance and almost no performance decay occurs during repeated compression, but when the compression amount is 90%, the compression modulus is reduced to 39.6 kPa; when the thickness is 0.6 cm, the total electromagnetic shielding performance can reach 64.0 dB, of which the surface reflection is 4.1 dB and the internal absorption is 59.9 dB.

[0051] Example 3

[0052] The difference between this example and Example 1 is that the mechanical stirring rate in step 2 is reduced to 1000 rpm, and the rest is the same, i.e. a 3D printed multi-scale structure graphene electromagnetic shielding macro body with super light, super strong elasticity and high electromagnetic shielding performance is obtained.

[0053] The obtained graphene oxide foaming slurry exhibits non-Newtonian fluid characteristics; the density of the obtained multi-scale structure graphene electromagnetic shielding macro body is 0.0056 g / cm 3 ; the conductivity is 46.5 S / m; it exhibits good rebound performance and when the compression amount is 90%, the compression modulus is 55.9 kPa; when the thickness is 0.6 cm, the total electromagnetic shielding performance can reach 65.7 dB, of which the surface reflection is 4.7 dB and the internal absorption is 61.0 dB.

[0054] Example 4

[0055] The embodiment is compared with the embodiment 1, the difference is only that the concentration of graphene oxide in step 1 is changed to 1.0wt%, and the rest is the same, that is, the multi-scale structure graphene electromagnetic shielding macroscopic body with super light, super strong elasticity and high electromagnetic shielding performance is obtained. The multi-scale structure graphene electromagnetic shielding macroscopic body obtained by the method has slightly increased density, and the elasticity, Young's modulus, conductivity and electromagnetic shielding capacity are all increased.

[0056] The obtained graphene oxide foaming slurry shows non-Newtonian fluid characteristics; the density of the obtained multi-scale structure graphene electromagnetic shielding macroscopic body is 0.0051g / cm 3 ; the conductivity is 40.2S / m; it shows good resilience performance, and the compression modulus is 85.4kPa when the compression amount is 90%; the total electromagnetic shielding performance can reach 79.5dB when the thickness is 0.6cm, of which the surface reflection is 4.6dB and the internal absorption is 74.9dB.

[0057] Embodiment 5

[0058] The embodiment is compared with the embodiment 1, the difference is that the alkyl glycoside in step 2 is changed to sodium dodecyl benzene sulfonate, and the addition amount of sodium dodecyl benzene sulfonate is also kept at 0.45g, and the rest is the same, that is, the multi-scale structure graphene electromagnetic shielding macroscopic body with super light, super strong elasticity and high electromagnetic shielding performance is obtained.

[0059] The obtained graphene oxide foaming slurry shows non-Newtonian fluid characteristics and has printability; the density of the obtained multi-scale structure graphene electromagnetic shielding macroscopic body is 0.0046g / cm 3 ; the conductivity can reach 37.5S / m; it also shows good resilience performance, and can immediately (within 1 second) recover to the original height after hundreds of compression cycles; the total electromagnetic shielding performance can reach 77.6dB when the thickness is 0.6cm, of which the surface reflection is 4.5dB and the internal absorption is 73.1dB.

[0060] Embodiment 6

[0061] The embodiment is compared with the embodiment 1, the difference is that 0.48g of cellulose is additionally added as a foam stabilizer in step 2, that is, the multi-scale structure graphene electromagnetic shielding macroscopic body with super light, super strong elasticity and high electromagnetic shielding performance is obtained.

[0062] The density of the obtained multi-scale structure graphene electromagnetic shielding macroscopic body is increased to 0.0098g / cm 3 , and the conductivity, mechanical properties and electromagnetic shielding performance are all slightly decreased.

[0063] Comparative example 1

[0064] Step 1: Exfoliated few-sheet graphene oxide was prepared using the conventional modified Hummers chemical oxidation method, and purified by dialysis to obtain an aqueous dispersion of graphene oxide with a concentration of 0.8 wt%.

[0065] Step 2: Place 60 mL of the mixture from Step 1 into a mold and freeze it directly in a -20°C freezer for 1 hour;

[0066] Step 3: Freeze-dry the frozen material from Step 2 to remove the internal ice crystals. The freeze-drying time is 24 hours. Then, heat-treat it at 500℃ for 1 hour under argon atmosphere protection at a heating rate of 5℃ / min to finally obtain a conventional graphene macroscopic body with good morphology.

[0067] Due to the absence of bubble clusters, the initial graphene oxide dispersion cannot be directly used for extrusion printing and must be formed using a mold; the density of the resulting conventional graphene macrostructure is 0.0071 g / cm³. 3 Its electrical conductivity can reach 74.4 S / m; however, its mechanical properties are poor. After several cycles of compression, it produces irreversible deformation exceeding 50% of its original height. When the thickness is 0.6 cm, its total electromagnetic shielding performance is 58.8 dB, of which surface reflection is 4.9 dB and internal absorption is 53.9 dB.

[0068] Comparative Example 2

[0069] Compared with Comparative Example 1, the only difference in this comparative example is that the heating rate in step 3 is adjusted to 20℃ / min. This ultimately leads to the structural disintegration of the material during high-temperature heat treatment, making it unable to maintain a stable macroscopic structure and thus lacking testing and application value.

[0070] Comparative Example 3

[0071] The only difference between this comparative example and Example 1 is that the concentration of the graphene oxide dispersion in step 1 is controlled at 0.4 wt%, while all other aspects remain the same. The graphene oxide foaming slurry obtained by this method has a low viscosity but still exhibits some fluidity. Furthermore, the bubble clusters have poor stability at room temperature and cannot effectively maintain their three-dimensional structure after extrusion. Therefore, it cannot be used as a printing ink to achieve customized shapes in extrusion printing.

[0072] Combination Figure 1 It can be seen that the 3D printed multi-scale mesh graphene macrostructure obtained by Example 1 of the present invention can maintain the original printed shape, with complete structure and good shape.

[0073] Combination Figure 2It can be seen that the multi-scale structure graphene electromagnetic shielding macroscopic body prepared by Example 1 has a bubble group as a template, and the nanosheet layers are self-assembled to form a few sheet layers wrapped spherical closed porous structure in an ordered and regular manner. The face-to-face stacking between the sheet layers is effectively inhibited, and the connection between the sheet layers is good, so that the multi-scale structure graphene electromagnetic shielding macroscopic body has excellent mechanical properties.

[0074] In combination Figure 3 It can be seen that the conventional graphene macroscopic body prepared by Comparative Example 1 has disordered and chaotic arrangement of sheet layers, serious sheet layer stacking, and weak connection between sheet layers. Therefore, after multiple compressions, the conventional graphene macroscopic body collapses obviously.

[0075] In combination Figure 4 It can be seen that when the compression amount is 50%, the multi-scale structure graphene electromagnetic shielding macroscopic body prepared by Example 1 can completely recover to the original height after 1000 compression cycles without obvious irreversible deformation, which exhibits good resilience.

[0076] In combination Figure 5 It can be seen that the conventional graphene macroscopic body prepared by Comparative Example 1 has obvious irreversible deformation after several compression cycles, and the deformation amount exceeds 50% of the original height.

[0077] In combination Figure 6 It can be seen that the conventional graphene macroscopic body prepared by Comparative Example 1 has the lowest electromagnetic shielding efficiency in the X wave band. With the introduction of the bubble group (Examples 1-3), a few nanosheet layers wrapped spherical closed porous structure connected to each other is formed in the multi-scale structure graphene electromagnetic shielding macroscopic body, which strengthens the multiple scattering and interference loss of the incident electromagnetic wave, improves the absorption of the incident electromagnetic wave, and finally makes the multi-scale structure graphene electromagnetic shielding macroscopic body exhibit more excellent electromagnetic wave shielding effect.

Claims

1. A method for preparing a multi-scale structure graphene macrobody, characterized in that, The preparation method comprises the following steps: (1) using chemical oxidation method to prepare exfoliated few-layer graphene oxide, obtaining graphene oxide aqueous dispersion as initial slurry; (2) adding surfactant to the graphene oxide aqueous dispersion in step (1), stirring to obtain bubble group filled graphene oxide slurry, obtaining foaming slurry, i.e. foaming ink for printing; (3) loading the foaming slurry obtained in step (2) into a syringe with a needle, continuously and smoothly extruding the slurry onto a low-temperature aluminum plate, and directly writing and printing to obtain a three-dimensional macroscopic body with a specific shape; (4) drying and forming and reducing the three-dimensional macroscopic body in step (3) to obtain a multi-scale structure graphene macroscopic body; The concentration of the graphene oxide dispersion is 0.5wt%-2wt%.

2. The production method according to claim 1, wherein The chemical oxidation method in step (1) comprises Hummers method, modified Hummers method, Brodie method and Staudenmaier method.

3. The production method according to claim 1, wherein The added surfactant in step (2) is any one of alkyl glycoside, sodium dodecyl benzene sulfonate and stearic acid; The mass ratio of the surfactant to graphene oxide in step (2) is 1:2-2:

1.

4. The production method according to claim 1, wherein The stirring mode in step (2) comprises any one or a combination of mechanical stirring, magnetic stirring and vortex oscillation.

5. The production method according to claim 1, wherein The inner diameter of the needle of the syringe in step (3) is 200-1000μm, the extrusion printing moving speed is 1-10mm / s, the extrusion pressure is 30-300kPa, and the surface temperature of the aluminum plate is-10-0℃.

6. The production method according to claim 1, wherein The drying and forming method in step (4) comprises freeze drying and CO2 supercritical drying.

7. The production method according to claim 1, wherein The reducing method in step (4) comprises any one of thermal reduction and chemical reduction.

8. The production method according to claim 1, wherein The preparation method comprises the following steps: (1) chemically oxidizing, exfoliating and centrifuging flake graphite to obtain graphene oxide dispersion; (2) mixing 0.5wt%-2wt% of the graphene oxide dispersion with a surfactant at a mass ratio of 1:2-2:1, mechanically stirring at a speed of 1000-3000r / min for 4-6min to obtain foaming slurry; (3) loading the foaming slurry in step (2) into a syringe, continuously extruding the slurry onto a low-temperature aluminum plate, the inner diameter of the needle of the syringe is 200-1000μm, the extrusion printing moving speed is 1-10mm / s, the extrusion pressure is 30-300kPa, and the surface temperature of the aluminum plate is-10-0℃, to obtain a three-dimensional macroscopic body with a specific shape; (4) freeze drying and thermally reducing the three-dimensional macroscopic body in step (3) to obtain a multi-scale structure graphene macroscopic body. The multi-scale structure graphene macroscopic body is prepared by the method in claim 1, and the multi-scale structure graphene macroscopic body has the advantages of individual customization, ultra-low density, ultra-strong elasticity and excellent electromagnetic shielding performance.

9. A multiscale structured graphene macrobody, characterized in that, The multi-scale structure graphene macroscopic body is applied to the field of electromagnetic shielding materials.

10. Use of the multiscale structured graphene macrobody according to claim 9, characterized in that, ​

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