Device and method for preparing graphene by electrophoretic hydrodynamic cavitation liquid exfoliation

Abstract

The application discloses a device and method for preparing graphene by electrophoretic hydrodynamic cavitation liquid phase stripping, which comprises a graphite flake raw material slurry tank, a diaphragm pump, a high-pressure pump, an electrophoretic high-pressure liquid phase stripping assembly, a first cyclone separator, a second cyclone separator, a graphene slurry tank and a wastewater tank; the diaphragm pump and the high-pressure pump are installed on a pipeline between the graphite flake raw material slurry tank and an input end of the electrophoretic high-pressure liquid phase stripping assembly; the first cyclone separator and the second cyclone separator are installed on a pipeline connected to an output end of the electrophoretic high-pressure liquid phase stripping assembly; a discharge port of the first cyclone separator is communicated with a feed port of the second cyclone separator; and a discharge port of the second cyclone separator is communicated with the graphene slurry tank. Compared with a traditional chemical method, the device has the advantages of green environmental protection, less defects of graphene structure and better preservation of characteristics of graphene; and compared with a traditional physical method, the device has the advantages of high production efficiency and better dispersibility.

Description

Technical Field

[0001] This invention relates to the field of carbon-based material preparation technology, and in particular to an apparatus and method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation. Background Technology

[0002] Graphene not only possesses excellent electrical properties and a perfect structure, but also exhibits unique characteristics such as outstanding thermal conductivity, high light transmittance, and an exceptionally large specific surface area. This makes graphene a promising candidate for applications in electronics, information technology, energy, and materials science. The rapid development of the graphene industry urgently requires the large-scale, batch production of high-quality graphene powder with controllable structure, thickness, and size. Based on the preparation mechanism, current methods for preparing graphene mainly include two types: chemical exfoliation and physical-mechanical exfoliation.

[0003] Chemical exfoliation uses graphite as a raw material. The graphite is pretreated to obtain a precursor, which is then exfoliated under external forces (such as ultrasound or centrifugation). Chemical exfoliation methods mainly include the following: intercalation-exfoliation, electrochemical exfoliation, and redox methods. The intercalation-exfoliation method involves using a specific organic solvent. The strong intercalation between the solvent and the carbon atom basal planes of graphite reduces the van der Waals forces between graphite layers, allowing direct exfoliation of graphene via ultrasonic or mechanical stirring. The redox method first pretreats the graphite. Under the action of an intercalating agent, the interlayer spacing between adjacent graphite sheets increases, generating precursors—graphite intercalation compounds (GICs). Then, under the strong oxidizing action of a strong oxidizing agent, oxygen-containing functional groups are generated above and below the carbon atom plane, further expanding the interlayer spacing. Finally, ultrasonic treatment completely destroys the van der Waals forces between the graphite sheets, yielding an intermediate product called graphite oxide. Under ultrasonic treatment, graphite oxide can be exfoliated into graphene oxide (GO). Under certain conditions, GO is reduced to remove the oxygen-containing functional groups on the carbon atom planes, repairing defects introduced during oxidation to obtain the target product—graphene. Existing chemical methods for preparation are complex, have relatively long preparation cycles, cause significant pollution, and are costly. Furthermore, the oxidation process inevitably introduces some irreparable defects, resulting in poor batch stability of graphene products and the loss of some of the inherent properties of graphene, thus limiting its downstream applications.

[0004] Mechanical exfoliation is a typical physical preparation method. This type of method uses highly oriented pyrolytic graphite (HOPG) as raw material and achieves graphite exfoliation under physical conditions. In 2004, Geim's research group at the University of Manchester successfully obtained 1-3 layer graphene sheets using HOPG as raw material via a "tape exfoliation method." Although this method can produce high-quality graphene with intact structures, it is too labor-intensive and has a low conversion rate, making it unsuitable for large-scale graphene production. Besides tape exfoliation, mechanical exfoliation methods also include electrostatic roller exfoliation, which uses HOPG as raw material and achieves successful graphite exfoliation through a rotating roller under electrostatic force; and wet ball milling, which uses the shear force provided by a ball mill to mechanically exfoliate graphite. However, due to their low conversion rates, these methods are unlikely to achieve large-scale graphene production. The patent specification with publication number CN108975321A discloses a method for preparing graphene using hydrocavitation technology. Using graphite and a dispersant as raw materials, the method utilizes hydrocavitation technology to generate a large number of cavitation bubbles, and the subsequent collapse of these bubbles (similar to traditional ultrasonic cavitation) to exfoliate graphite and produce graphene. However, this method has shortcomings. Due to the small interlayer spacing and hydrophobic nature of graphite, bubbles are difficult to generate between the graphite layers during hydrocavitation. Similar to traditional mechanical exfoliation methods, it still suffers from low exfoliation efficiency and a low degree of exfoliation. Furthermore, this process introduces a large amount of organic surfactants, causing graphene to lose some of its inherent properties.

[0005] In summary, although the industrial production of graphene and related products have been reported and are available on the market, there is still a contradiction between achieving green environmental protection, price, quality and batch stability simultaneously, which greatly restricts the development of graphene and its downstream industries. Therefore, developing a new, efficient, green, and controllable method for preparing high-quality graphene remains a key research focus and an urgent problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems in the prior art and to provide an apparatus and method for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation.

[0007] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0008] An apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation includes a graphite flake raw material slurry tank, a diaphragm pump, a high-pressure pump, an electrophoretic high-pressure liquid-phase exfoliation component, a primary cyclone separator, a secondary cyclone separator, a graphene slurry tank, and a wastewater tank. The diaphragm pump and the high-pressure pump are installed on the pipeline between the graphite flake raw material slurry tank and the input end of the electrophoretic high-pressure liquid-phase exfoliation component. The primary cyclone separator and the secondary cyclone separator are installed on the pipeline connected to the output end of the electrophoretic high-pressure liquid-phase exfoliation component. The wastewater outlets of the primary and secondary cyclone separators are connected to the wastewater tank. The discharge port of the primary cyclone separator is connected to the inlet of the secondary cyclone separator, and the discharge port of the secondary cyclone separator is connected to the graphene slurry tank.

[0009] Furthermore, in the above-mentioned apparatus for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation, the electrophoretic high-pressure liquid phase exfoliation component includes a high-pressure liquid phase exfoliation tube. The two ends of the high-pressure liquid phase exfoliation tube are respectively provided with an inlet pipe and an outlet pipe communicating with their inner cavity. A positive electrode and a negative electrode are installed on the outside of the high-pressure liquid phase exfoliation tube. An electrode mesh, a hard alloy porous plate, and a negative electrode porous copper electrode plate are installed in the inner cavity of the high-pressure liquid phase exfoliation tube. The hard alloy porous plate and the negative electrode porous copper electrode plate are fitted together, with the negative electrode porous copper electrode plate positioned close to the electrode mesh. The electrode mesh is connected to an external positive electrode via leads. The hard alloy porous plate and the negative electrode porous copper electrode plate are connected to an external negative electrode via leads. The inner cavity region of the high-pressure liquid phase exfoliation tube between the electrode mesh and the inlet pipe serves as a high-pressure chamber, and the inner cavity region of the high-pressure liquid phase exfoliation tube between the negative electrode porous copper electrode plate and the outlet pipe serves as a cavitation exfoliation chamber.

[0010] Furthermore, in the above-mentioned apparatus for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation, the two ends of the high-pressure liquid phase exfoliation tube are provided with end caps, and the feed pipe and the discharge pipe are installed on the corresponding end caps.

[0011] Furthermore, in the above-mentioned apparatus for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation, an ultrasonic generator is also installed on the end cap where the discharge pipe is located.

[0012] Furthermore, in the above-mentioned apparatus for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation, the electrode mesh is a circular sheet-like platinum electrode mesh.

[0013] A method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation, based on the above-mentioned apparatus, specifically includes the following steps:

[0014] 1) The natural flake graphite raw material to be used is stored in the form of graphite flake raw material slurry tank in the form of slurry. The bottom of the tank is connected to the inlet of the diaphragm pump by a pipe. The diaphragm pump provides the power to transport the slurry. The diaphragm pump is driven by compressed air, and the compressed air is an adjustable pulse flow rate air source.

[0015] 2) The outlet of the diaphragm pump is connected to the inlet of the high-pressure pump above. The high-pressure pump pressurizes the graphite flake raw material slurry and delivers it to the feed port of the electrophoretic high-pressure liquid phase stripping component. There is an ultra-high pressure sensor at the pump outlet.

[0016] 3) The positive and negative electrodes outside the electrophoretic high-pressure liquid phase stripping component are connected to DC power. The graphite flakes entering the electrophoretic high-pressure liquid phase stripping component flow in a parallel arrangement of sheet-like layers under the action of electric field and pass through the pores of the porous plate. The electrophoresis voltage is set at 3-5V per centimeter of electrode spacing.

[0017] 4) Graphite flakes through pores are rapidly depressurized in the cavitation exfoliation chamber and cavitation exfoliation is carried out to generate graphene slurry. The graphene slurry is prevented from coagulation and agglomeration due to low flow rate under the action of ultrasound.

[0018] 5) The graphene slurry is transported through the outlet of the electrophoretic high-pressure liquid phase stripping component to the primary and secondary cyclone separators via pipeline, where it is concentrated under the action of cyclone separation.

[0019] 6) The graphene suspension slurry concentrated by cyclone separation is collected in a graphene slurry tank, and the discharged wastewater is stored in a wastewater tank.

[0020] Furthermore, in the method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation as described above, in step 1), an alkaline aqueous solution and natural flake graphite are mixed under ultrasonic treatment conditions with mechanical stirring assistance to form a slurry. The ultrasonic treatment conditions with mechanical stirring assistance are: power of 500-700W, frequency of 10-30kHz, and mechanical stirring speed of 1000-4000rpm. The alkaline aqueous solution in the slurry is a potassium hydroxide or sodium hydroxide aqueous solution, wherein the content of potassium hydroxide or sodium hydroxide is 0.1-1.0wt%. The amount of natural flake graphite added to the slurry is 0.1-5.0wt% of the aqueous solution.

[0021] Furthermore, in the method for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation as described above, in step 1), the rated flow rate of the diaphragm pump is 1-20 L / min, and the flow rate of the diaphragm pump is controlled by the pressure feedback of the high-pressure pump to control the pulse flow rate of the gas source.

[0022] Furthermore, in the method for preparing graphene by electrophoretic hydrocavitation liquid phase exfoliation as described above, in step 2), the pressure range of the high-pressure pump is 50-200 MPa.

[0023] Furthermore, in the method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation as described above, in step 4), the ultrasonic frequency is below 30 kHz to ensure cavitation effect; the ultrasonic vertical power density is not less than 0.5 W / cm². 2 .

[0024] The beneficial effects of this invention are:

[0025] This invention uses electrophoretic hydrocavitation liquid phase exfoliation to prepare graphene. Compared with traditional chemical methods, it not only has the advantages of being green and environmentally friendly, but also produces graphene with fewer structural defects and better preserves the characteristics of graphene. Compared with traditional physical methods, it has higher production efficiency and better dispersibility.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the above advantages at the same time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention;

[0029] Figure 2 This is a schematic diagram of the electrophoretic high-pressure liquid phase stripping component in the device of the present invention;

[0030] Figure 3 Here is a SEM image of the graphene obtained in the embodiments of the present invention;

[0031] Figure 4 This is a TEM image of the graphene obtained in an embodiment of the present invention;

[0032] Figure 5 Here is an HRTEM image of the graphene obtained in an embodiment of the present invention;

[0033] Figure 6 The image shows the AFM image of the graphene sheet obtained in the embodiment of the present invention.

[0034] Figure 7 This is a histogram of the thickness dimensions of the graphene sheets obtained in the embodiments of the present invention;

[0035] Figure 8 This is a histogram of the lateral dimensions of the graphene sheets obtained in the embodiments of the present invention;

[0036] Figure 9 This is an STM image of the graphene sheet obtained in an embodiment of the present invention;

[0037] The attached diagram lists the components represented by each number as follows:

[0038] 1-Graphite flake raw material slurry tank, 2-Diaphragm pump, 3-High pressure pump, 4-Electrophoretic high-pressure liquid phase stripping assembly, 401-High pressure liquid phase stripping tube, 402-Infeed pipe, 403-Outfeed pipe, 404-Electrode mesh, 405-Positive electrode, 406-Positive electrode porous copper plate, 407-Hard alloy porous plate, 408-Negative electrode, 409-High pressure chamber, 410-Cavitation stripping chamber, 411-Ultrasonic generator, 5-First-stage cyclone separator, 6-Second-stage cyclone separator, 7-Graphene slurry tank, 8-Wastewater tank. Detailed Implementation

[0039] 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 are within the scope of protection of the present invention.

[0040] This invention firstly utilizes the morphological characteristics and electrocoagulation properties of natural graphene flakes to achieve uniform sorting into a porous hydraulic cavitation plate via electrophoresis, and rapidly depressurizes and cavitates to exfoliate and generate graphene. Based on this principle, an electrophoretic and hydraulic cavitation synergistic enhancement device for graphene preparation is designed and manufactured. Secondly, graphene is prepared using this device. The specific process includes: ultrasonic surface modification of graphite in liquid phase, mechanical liquid phase stirring and diffusion of modified graphite, and efficient liquid phase exfoliation through hydraulic cavitation.

[0041] An apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation, such as... Figure 1-2 As shown, the system includes a graphite flake raw material slurry tank 1, a diaphragm pump 2, a high-pressure pump 3, an electrophoretic high-pressure liquid phase stripping assembly 4, a primary cyclone separator 5, a secondary cyclone separator 6, a graphene slurry tank 7, and a wastewater tank 8. The diaphragm pump 2 and the high-pressure pump 3 are installed on the pipeline between the graphite flake raw material slurry tank 1 and the input end of the electrophoretic high-pressure liquid phase stripping assembly 4. The primary cyclone separator 5 and the secondary cyclone separator 6 are installed on the pipeline connected to the output end of the electrophoretic high-pressure liquid phase stripping assembly 4. The wastewater outlets of the primary cyclone separator 5 and the secondary cyclone separator 6 are connected to the wastewater tank 8. The discharge port of the primary cyclone separator 5 is connected to the inlet of the secondary cyclone separator 6, and the discharge port of the secondary cyclone separator 6 is connected to the graphene slurry tank 7.

[0042] In this invention, the electrophoretic high-pressure liquid phase stripping assembly 4 includes a high-pressure liquid phase stripping tube 401. The two ends of the high-pressure liquid phase stripping tube 401 are respectively provided with an inlet pipe 402 and an outlet pipe 403 communicating with its inner cavity. A positive electrode 405 and a negative electrode 408 are installed on the outside of the high-pressure liquid phase stripping tube 401. An electrode mesh 404, a hard alloy porous plate 407, and a negative electrode porous copper electrode plate 406 are installed in the inner cavity of the high-pressure liquid phase stripping tube 401. The hard alloy porous plate 407 and the negative electrode porous copper electrode plate 406 are fitted together (the through holes are connected one-to-one), and the negative electrode porous copper electrode plate 406 is positioned close to the electrode mesh 404. The electrode mesh 404 is a circular sheet-shaped platinum electrode mesh. The electrode mesh 404 is connected to the external positive electrode 405 via leads, and the hard alloy porous plate 407 and the negative electrode porous copper electrode plate 406 are connected to the external negative electrode 408 via leads. The high-pressure liquid phase stripping tube 401 is located in the inner cavity area between the electrode mesh 404 and the feed pipe 402 as the high-pressure chamber 409, and the high-pressure liquid phase stripping tube 401 is located in the inner cavity area between the negative electrode porous copper electrode plate 406 and the discharge pipe 403 as the cavitation stripping chamber 410.

[0043] In this invention, the high-pressure liquid phase stripping tube 401 has end caps at both ends, and the feed pipe 402 and the discharge pipe 403 are installed on the corresponding end caps. An ultrasonic generator 411 is also installed on the end cap where the discharge pipe 403 is located.

[0044] A method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation, the method specifically includes the following steps:

[0045] 1) The natural flake graphite raw material to be used is stored in the form of graphite flake raw material slurry tank 1 in the form of slurry. The bottom of the tank is connected to the inlet of diaphragm pump 2 by a pipe. Diaphragm pump 2 provides the power for slurry transportation. Diaphragm pump 2 is driven by compressed air, and the compressed air is an adjustable pulse flow rate air source. Alkaline aqueous solution and natural flake graphite are mixed to form slurry under ultrasonic treatment with mechanical stirring assistance. The ultrasonic treatment conditions with mechanical stirring assistance are: power of 500-700W, frequency of 10-30kHz, and mechanical stirring speed of 1000-4000rpm. The alkaline aqueous solution in the slurry is potassium hydroxide or sodium hydroxide aqueous solution, and the content of potassium hydroxide or sodium hydroxide is 0.1-1.0wt%. The amount of natural flake graphite added to the slurry is 0.1-5.0wt% of the aqueous solution. The rated flow rate range of diaphragm pump 2 is 1-20L / min. The flow rate of diaphragm pump is controlled by the pressure feedback of high pressure pump to control the pulse flow rate of air source.

[0046] 2) The outlet of diaphragm pump 2 is connected to the inlet of high pressure pump 3 above. High pressure pump 3 pressurizes the graphite flake raw material slurry and delivers it to the feed port of electrophoretic high pressure liquid phase stripping component 4. The pump outlet has an ultra-high pressure sensor; the pressure range of the high pressure pump is 50-200MPa.

[0047] 3) The positive and negative electrodes outside the electrophoretic high-pressure liquid phase stripping component 4 are connected to DC power. The graphite flakes entering the electrophoretic high-pressure liquid phase stripping component 4 flow in a parallel arrangement of sheet-like layers under the action of the electric field and pass through the pores of the porous plate. The electrophoresis voltage is set at 3-5V per centimeter of electrode spacing.

[0048] 4) Graphite flakes through pores are rapidly depressurized in the cavitation exfoliation chamber, resulting in the formation of graphene slurry through interlayer cavitation exfoliation. The graphene slurry is subjected to ultrasonic waves to prevent agglomeration and aggregation due to low flow rates; the ultrasonic frequency is below 30kHz to ensure effective cavitation; and the ultrasonic vertical power density is not less than 0.5W / cm³. 2 ;

[0049] 5) The graphene slurry is transported through the outlet of the electrophoretic high-pressure liquid phase stripping component 4 to the first-stage cyclone separator 5 and the second-stage cyclone separator 6, where it is concentrated under the action of cyclone separation.

[0050] 6) The graphene suspension slurry concentrated by cyclone separation is collected in graphene slurry tank 7, and the discharged wastewater is stored in wastewater tank 8.

[0051] Specific embodiments of the present invention are as follows:

[0052] Example

[0053] 10g of sodium hydroxide powder was dissolved in 1kg of water. After dissolution, 20g of graphite was added, and the mixture was ultrasonically dispersed for 1 hour under mechanical stirring at 1000rpm (ultrasonic power 500W, frequency 10kHz) to form a stable graphite slurry. This slurry was then stored in graphite flake raw material slurry tank 1. The power air source was turned on, and the pressure was adjusted to 0.6MPa. Diaphragm pump 2 was put on standby, and the pressure of high-pressure pump 3 was adjusted to 150MPa. This pressure setting was fed back to the pulse flow rate adjustable compressed air source to control the output flow rate of diaphragm pump 2 and ensure the stability of the inlet pressure of high-pressure pump 3.

[0054] Connect the positive and negative terminals of the adjustable DC power supply output to the positive and negative electrodes on the outside of the electrophoretic high-pressure liquid phase stripping assembly 4, with an electrode spacing of approximately 20 cm and a voltage setting of 80 V. Turn on the ultrasonic generator, setting the frequency to 25 kHz and the power density to 0.5 W / cm². 2 .

[0055] When the high-pressure pump 3 is switched on, the diaphragm pump 2 feeds the material. The natural graphite flake slurry enters the feed inlet of the electrophoretic high-pressure liquid phase exfoliation component 4 at a constant flow rate and pressure via the diaphragm pump 2 and the high-pressure pump 3. It is then decelerated and mixed in the high-pressure chamber 409. Flowing through the positive platinum electrode mesh 404 and between the positive platinum electrode mesh 404 and the negative porous copper electrode plate 406, the graphite flakes in the deionized water are aligned in a parallel direction under the influence of an electric field. The oriented graphite flake suspension passes through the negative porous copper electrode plate 406 and then the hard alloy porous plate 407, where it is rapidly depressurized to atmospheric pressure. The enormous expansion force generated by the vaporization of water molecules causes the graphite layers to exfoliate, forming a graphene suspension. The ultrasonic waves enhance cavitation, maintain, and prevent the exfoliated graphene from agglomerating.

[0056] The graphene suspension is transported to the first-stage cyclone separator 5 via pipeline. Due to the density difference with water, some water is removed under the action of centrifugal force and discharged into the wastewater tank 8. The resulting high-concentration graphene suspension enters the second-stage cyclone separator 6. In the second-stage cyclone separator 6, the rotation speed is increased for further dehydration, resulting in an even higher-concentration graphene suspension that enters the graphene slurry tank 7.

[0057] The wastewater removed in the two steps is about 80% of the original suspension slurry. After entering the wastewater tank 8 and waiting for cooling, it can be used as water for the next production without further treatment.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation, characterized in that: The system includes a graphite flake raw material slurry tank, a diaphragm pump, a high-pressure pump, an electrophoretic high-pressure liquid phase stripping assembly, a primary cyclone separator, a secondary cyclone separator, a graphene slurry tank, and a wastewater tank. A diaphragm pump and a high-pressure pump are installed on the pipeline between the graphite flake raw material slurry tank and the input end of the electrophoretic high-pressure liquid phase stripping assembly. A primary cyclone separator and a secondary cyclone separator are installed on the pipeline connected to the output end of the electrophoretic high-pressure liquid phase stripping assembly. The wastewater outlets of the primary and secondary cyclone separators are connected to the wastewater tank. The discharge port of the primary cyclone separator is connected to the inlet of the secondary cyclone separator. The discharge port of the secondary cyclone separator is connected to the graphene slurry tank. The electrophoretic high-pressure liquid phase stripping assembly includes a high-pressure liquid phase stripping tube. The two ends of the high-pressure liquid phase stripping tube are respectively provided with an inlet pipe and an outlet pipe communicating with its inner cavity. A positive electrode and a negative electrode are installed on the outside of the high-pressure liquid phase stripping tube. An electrode mesh, a hard alloy porous plate, and a negative electrode porous copper electrode plate are installed in the inner cavity of the high-pressure liquid phase stripping tube. The hard alloy porous plate and the negative electrode porous copper electrode plate are fitted together, with the negative electrode porous copper electrode plate positioned close to the electrode mesh. The electrode mesh is connected to an external positive electrode via leads. The hard alloy porous plate and the negative electrode porous copper electrode plate are connected to an external negative electrode via leads. The inner cavity region of the high-pressure liquid phase stripping tube between the electrode mesh and the inlet pipe serves as a high-pressure chamber, and the inner cavity region of the high-pressure liquid phase stripping tube between the negative electrode porous copper electrode plate and the outlet pipe serves as a cavitation stripping chamber.

2. The apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 1, characterized in that: The high-pressure liquid phase stripping tube is provided with end caps at both ends, and the feed pipe and discharge pipe are installed on the corresponding end caps.

3. The apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 2, characterized in that: An ultrasonic generator is also installed on the end cap where the discharge pipe is located.

4. The apparatus for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 1, characterized in that: The electrode mesh is a circular sheet-shaped platinum electrode mesh.

5. A method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation, characterized in that, This method, based on the apparatus according to any one of claims 1-4, specifically includes the following steps: 1) The natural flake graphite raw material to be used is stored in the form of graphite flake raw material slurry tank in the form of slurry. The bottom of the tank is connected to the inlet of the diaphragm pump by a pipe. The diaphragm pump provides the power to transport the slurry. The diaphragm pump is driven by compressed air, and the compressed air is an adjustable pulse flow rate air source. 2) The outlet of the diaphragm pump is connected to the inlet of the high-pressure pump above. The high-pressure pump pressurizes the graphite flake raw material slurry and delivers it to the feed port of the electrophoretic high-pressure liquid phase stripping component. There is an ultra-high pressure sensor at the pump outlet. 3) The positive and negative electrodes outside the electrophoretic high-pressure liquid phase stripping component are connected to DC power. The graphite flakes entering the electrophoretic high-pressure liquid phase stripping component flow in a parallel arrangement of sheet-like layers under the action of electric field and pass through the pores of the porous plate. The electrophoresis voltage is set at 3-5V per centimeter of electrode spacing. 4) Graphite flakes through pores are rapidly depressurized in the cavitation exfoliation chamber and cavitation exfoliation is carried out to generate graphene slurry. The graphene slurry is prevented from coagulation and agglomeration due to low flow rate under the action of ultrasound. 5) The graphene slurry is transported through the outlet of the electrophoretic high-pressure liquid phase stripping component to the primary and secondary cyclone separators via pipeline, where it is concentrated under the action of cyclone separation. 6) The graphene suspension slurry concentrated by cyclone separation is collected in a graphene slurry tank, and the discharged wastewater is stored in a wastewater tank.

6. The method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 5, characterized in that: In step 1), an alkaline aqueous solution and natural flake graphite are mixed under ultrasonic treatment with mechanical stirring assistance to form a slurry. The ultrasonic treatment conditions with mechanical stirring assistance are: power of 500-700W, frequency of 10-30kHz, and mechanical stirring speed of 1000-4000rpm. The alkaline aqueous solution in the slurry is a potassium hydroxide or sodium hydroxide aqueous solution, wherein the content of potassium hydroxide or sodium hydroxide is 0.1-1.0wt%. The amount of natural flake graphite added to the slurry is 0.1-5.0wt% of the aqueous solution.

7. The method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 5, characterized in that: In step 1), the rated flow range of the diaphragm pump is 1-20 L / min, and the flow rate of the diaphragm pump is controlled by the pressure feedback control of the high-pressure pump to control the pulse flow rate of the air source.

8. The method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 5, characterized in that: In step 2), the pressure range of the high-pressure pump is 50-200MPa.

9. The method for preparing graphene by electrophoretic hydrocavitation liquid-phase exfoliation according to claim 5, characterized in that: In step 4), the ultrasonic frequency is below 30kHz to ensure cavitation effect; the ultrasonic vertical power density is not less than 0.5W / cm². 2 .

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