System and method for continuously preparing graphene by electrochemical stripping method

Abstract

The invention discloses a system for continuously preparing graphene through an electrochemical stripping method. The system comprises a stripping assembly, a separating and collecting assembly and a continuous material supplementing assembly. The stripping assembly comprises an electrolytic tank, a graphite electrode device and a counter electrode device, electrolyte is contained in the electrolytic tank, the graphite electrode device and the counter electrode device are both immersed in the electrolyte, the graphite electrode device is coaxially arranged in the counter electrode device, the graphite electrode device is connected with the positive electrode of the direct-current power source through a positive wire, and the counter electrode device is connected with the negative electrode of the direct-current power source through a negative wire. The counter electrode device is connected with the cathode of the direct-current power supply through a cathode wire; and the continuous material supplementing assembly is communicated with the electrolytic tank through a material supplementing pipeline. The invention further discloses a method for continuously preparing the graphene through the electrochemical stripping method. The device has the beneficial effects that the graphite electrode device and the counter electrode device are coaxially arranged inside and outside to form an annular electrode structure, so that the electric field edge effect of a planar electrode is avoided, the electric field distribution is more uniform, and the intercalation and stripping efficiency between graphite layers is further improved.

Description

Technical Field

[0001] This invention relates to the field of graphene preparation technology, specifically to a system and method for the continuous preparation of graphene by electrochemical exfoliation. Background Technology

[0002] Currently, large-scale graphene production still faces challenges. Electrochemical exfoliation has attracted attention due to its simple process, low cost, and environmental friendliness. Its core is to embed graphite layers under the ion electric field of the electrolyte, and then exfoliate using gas or mechanical force. However, existing technologies have significant shortcomings: 1. Low exfoliation efficiency: The uneven electric field distribution of traditional planar electrodes leads to excessively high current density in some areas (edge ​​effect) or excessively low current density in the central region, resulting in some graphite not being fully exfoliated; 2. Unstable product quality: Uneven exfoliation leads to large differences in the number of graphene layers (mixture of single and multilayer layers), and it is easy to introduce structural defects (such as pores and excessive functional groups) due to local over-etching; 3. Poor process continuity: Large graphite sheets are prone to detaching and settling to the bottom of the electrolytic cell, making continuous production difficult and requiring frequent shutdowns for cleaning.

[0003] Therefore, it is essential to design a new technology for the continuous preparation of graphene. Summary of the Invention

[0004] The purpose of this invention is to provide a system and method for the continuous preparation of graphene by electrochemical exfoliation, addressing the shortcomings of existing technologies and aiming to solve the problem of low exfoliation efficiency in existing technologies.

[0005] The technical solution adopted in this invention is: a system for continuous preparation of graphene by electrochemical exfoliation, comprising an exfoliation component, a separation and collection component, and a continuous feeding component; The stripping assembly includes an electrolytic cell, a graphite electrode device as described in claim 1, and a counter electrode device. The electrolytic cell is filled with an electrolyte, and both the graphite electrode device and the counter electrode device are immersed in the electrolyte. The graphite electrode device is coaxially disposed inside the counter electrode device. The graphite electrode device is connected to the positive terminal of a DC power supply via a positive electrode wire, and the counter electrode device is connected to the negative terminal of a DC power supply via a negative electrode wire. The inlet of the separation and collection component is connected to the outlet at the bottom of the electrolytic cell via an outlet pipe; The continuous feeding assembly is connected to the electrolytic cell via a feeding pipe, and is used to continuously replenish the electrolyte in the electrolytic cell and continuously provide graphite sheets to the graphite electrode device.

[0006] According to the above scheme, the graphite electrode device includes an insulating mesh cylinder, a conductive metal sheet, and an insulating clamp; The lower end of the insulating mesh tube is closed, and the upper end is open; the conductive metal sheet is fixed to the upper part of the insulating mesh tube by an insulating clamp, and the conductive metal sheet is used to connect to the positive electrode wire. The graphite sheet to be peeled is rolled into a cylindrical shape that runs from top to bottom, and fixed to the inner wall of the insulating mesh cylinder by an insulating clamp, with the graphite sheet in contact with the conductive metal sheet.

[0007] According to the above scheme, the counter electrode device includes a platinum sheet, which is rolled into a cylindrical shape that runs through the top and bottom and is fixed by fasteners at the top and bottom ends; the inner surface of the platinum sheet is provided with scale lines at equal intervals to indicate its rolling diameter; the platinum sheet is connected to the negative electrode wire.

[0008] According to the above scheme, the continuous feeding assembly further includes a curling device, which includes a coaxial and innerly arranged curling outer cylinder and a curling inner cylinder, as well as a curling outer pulley installed outside the curling outer cylinder and a curling inner pulley installed inside the curling inner cylinder. An annular curled cavity for accommodating graphite sheets is left between the curled outer cylinder and the curled inner cylinder. The axes of the outer and inner coiled pulleys are vertical. The outer and inner coiled pulleys are arranged in pairs to form a coiled pulley group. The two are respectively connected to the corresponding pulley drive components. The rotation is achieved by driving the pulley drive components, and the distance between the outer and inner traction pulleys can be adjusted. Both the outer and inner curling pulleys are in contact with the graphite sheet inserted into the curling cavity, and they rotate in opposite directions to drive the graphite sheet to curl.

[0009] According to the above scheme, the continuous feeding assembly also includes a traction device for pulling the rolled-up graphite sheet into the insulating mesh cylinder. The traction device includes a coaxial inner traction cylinder and an outer traction cylinder arranged inside and outside the outer traction cylinder, as well as an outer traction pulley installed outside the outer traction cylinder and an inner traction pulley installed inside the inner traction cylinder. An annular traction cavity for accommodating graphite sheets is provided between the outer traction cylinder and the inner traction cylinder. The axes of the outer traction pulley and the inner traction pulley are horizontal. The outer traction pulley and the inner traction pulley are arranged in pairs to form a traction pulley group, and are respectively connected to the corresponding pulley drive assembly. The rotation is achieved by driving the pulley drive assembly, and the distance between the outer traction pulley and the inner traction pulley can be adjusted. Both the outer and inner traction pulleys are in contact with the graphite sheet inserted into the traction cavity, and they rotate in opposite directions to pull the graphite sheet downward.

[0010] According to the above scheme, each pulley is a metal part, and the outside of the pulley is completely covered with a rubber layer, with an optical fiber strain sensor built into the rubber layer.

[0011] According to the above scheme, the separation and collection assembly includes a discharge centrifugal pump and a hydrocyclone separator. The discharge centrifugal pump is located on the discharge pipe, the outlet of the discharge pipe is connected to the inlet of the hydrocyclone separator, and the top overflow port of the hydrocyclone separator is connected to the liquid storage tank of the continuous feeding assembly.

[0012] According to the above scheme, the system also includes a controller, a voltage sensor, a temperature sensor, and an optical fiber strain sensor; The voltage sensor is connected in parallel to the wire connecting the graphite electrode device and the counter electrode device to collect the circuit operating voltage; the temperature sensor is located inside the electrolytic cell to detect the electrolyte temperature; the fiber optic strain sensor is located in the adhesive layer of the pulley of the continuous feeding assembly to monitor the tension of the graphite sheet. The controller is connected to the voltage sensor, temperature sensor, fiber optic strain sensor, and each pulley drive assembly of the continuous feeding assembly.

[0013] This invention also employs a method for the continuous preparation of graphene via electrochemical exfoliation, comprising the following steps: Assemble the system for continuous preparation of graphene by electrochemical exfoliation as described in claim 8; The electrolyte is added separately to the storage tanks of the electrolytic cell and the continuous feeding assembly; Insert the lower end of the graphite sheet into the curling cavity of the curling device, and use the curling device to curl the lower end of the graphite sheet into a cylindrical shape; Start the traction device to pull the rolled graphite sheet into the insulating mesh tube of the graphite electrode device. Adjust the graphite sheet feeding speed according to the voltage fluctuation and temperature change in the electrolytic cell, and adjust the traction pulley spacing according to the graphite sheet tension. The graphite sheet is immersed in the electrolyte of the electrolytic cell, and the circuit is connected to perform electrochemical stripping of the graphite sheet. Collect the mixed slurry generated during the stripping process in the electrolytic cell. The mixed slurry includes incompletely stripped graphite fragments and an electrolyte containing suspended graphene products. The mixed slurry is fed to a hydrocyclone separator, where graphite fragments at the bottom and a dispersion of graphene-containing products and electrolyte at the top are separated.

[0014] According to the above scheme, the method for adjusting the graphite sheet feeding speed based on voltage fluctuations and temperature changes within the electrolytic cell is as follows: The controller detects voltage fluctuations and reaction temperature changes in the electrolytic cell to determine the peeling efficiency. If the operating voltage rises and exceeds the set peeling voltage, or the real-time temperature in the electrolytic cell rises and exceeds the set temperature range, the controller will reduce the feeding speed of the graphite sheets and extend the graphite material peeling time by controlling the pulley drive component corresponding to the traction pulley group. Conversely, it will control the pulley drive component corresponding to the traction pulley group to increase the feeding speed of the graphite sheets.

[0015] The beneficial effects of this invention are as follows: 1. In this invention, the graphite electrode device and the counter electrode device are arranged coaxially inside and outside to form a ring electrode structure. This design can increase the relative area of ​​the positive and negative electrodes, effectively avoid the edge effect of the electric field of the planar electrode, make the electric field distribution more uniform, thereby improving the efficiency of graphite interlayer intercalation and peeling, reducing defects caused by local energy concentration, and significantly improving the quality of the finished product.

[0016] 2. This invention, through the design of a continuous feeding assembly, a winding device, and a traction device, can achieve both a stable supply of electrolyte and automatic feeding of graphite sheets; simultaneously, the collection and separation assembly can separate and collect the stripped products. Compared with existing technologies, this invention enables continuous production. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of Example 1.

[0018] Figure 2 This is a schematic diagram of the graphite electrode device in Example 1.

[0019] Figure 3 This is a front view of the graphite electrode device in Embodiment 1 (excluding the positive electrode wire).

[0020] Figure 4 This is a top view of the insulating mesh cylinder in Example 1 (excluding the positive conductor).

[0021] Figure 5 This is a schematic diagram of the electrode device in Embodiment 1.

[0022] Figure 6 This is a schematic diagram of the platinum sheet insertion in Example 1.

[0023] Figure 7 This is a schematic diagram showing the arrangement of the winding device and the traction device in Example 1.

[0024] Figure 8 This is a schematic diagram of the curling device in Example 1. Figure 1 .

[0025] Figure 9 This is a schematic diagram of the curling device in Example 1. Figure 2 .

[0026] Figure 10 This is a schematic diagram of the traction device in Embodiment 1. Figure 1 .

[0027] Figure 11 This is a schematic diagram of the traction device in Embodiment 1. Figure 2 .

[0028] Figure 12 This is a connection diagram for a voltage sensor.

[0029] Figure 13 This is a schematic diagram of the pulley drive assembly in Embodiment 1. Figure 1 .

[0030] Figure 14 This is a schematic diagram of the pulley drive assembly in Embodiment 1. Figure 2 .

[0031] The components include: 1. Electrolytic cell; 2. Storage tank; 3. Feeding centrifugal pump; 4. Feeding pipeline; 5. Discharge pipeline; 6. Discharge centrifugal pump; 7. Graphite sheet; 8. Traction device; 8-1. Traction outer cylinder; 8-2. Traction inner cylinder; 8-3. Traction outer pulley; 8-4. Traction inner pulley; 9. Coiling device; 9-1. Coiling outer cylinder; 9-2. Coiling inner cylinder; 9-3. Coiling outer pulley; 9-4. Coiling inner pulley; 10. Graphite electrode device; 10-1. Insulating mesh cylinder; 10-2. Conductive metal sheet; 10-3 Insulating clamp; 11 Counter electrode device; 11-1 Platinum sheet; 11-2 Fixing buckle; 12 Hydrocyclone separator; 13 Positive electrode wire; 14 Negative electrode wire; 15 Pulley telescopic drive component; 15-1 Linear drive motor; 15-2 Ball screw pair; 15-3 Bracket; 15-4 Guide rail; 16 Pulley rotation drive component; 16-1 Rotary drive motor; 16-2 Universal telescopic coupling; 17 Voltage sensor; 18 Graphene and electrolyte treatment device. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In the description of the embodiments of this application, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0035] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, the term "a plurality of" indicates two or more.

[0037] Example 1 like Figure 1 The system shown is for the continuous preparation of graphene by electrochemical exfoliation, including an exfoliation component, a separation and collection component, and a continuous feeding component; The stripping assembly includes an electrolytic cell 1, a graphite electrode device 10, and a counter electrode device 11; The electrolytic cell 1 is filled with electrolyte; The graphite electrode device 10 and the counter electrode device 11 are both immersed in the electrolyte of the electrolytic cell 1, and the graphite electrode device 10 is coaxially arranged inside the counter electrode device 11. The graphite electrode device 10 is connected to the positive terminal of the DC power supply via the positive electrode wire 13, and the counter electrode device 11 is connected to the negative terminal of the DC power supply via the negative electrode wire 14. The graphite electrode device 10, the counter electrode device 11, and the DC power supply form a circuit. The inlet of the separation and collection component is connected to the outlet at the bottom of the electrolytic cell 1 through the outlet pipe 5; The continuous feeding assembly is connected to the electrolytic cell 1 through the feeding pipe 4.

[0038] In this invention, the exfoliation assembly is used to exfoliate the graphite layer to prepare graphene products; the separation and collection assembly is used to separate and collect the graphene products, electrolyte, and graphite fragments that have been exfoliated; the continuous feeding assembly is used to continuously replenish the electrolyte for the electrolytic cell 1 and continuously provide graphite sheets 7 for the graphite electrode device 10; the electrolyte can be any one of inorganic salt electrolyte, organic electrolyte, ionic liquid, etc.

[0039] In this invention, the graphite fragments specifically refer to graphite semi-finished products that have not been fully dissociated during the exfoliation process, have a layer thickness of more than 30 layers, and are prone to settling, and can be recycled and exfoliated again in the future; the graphene products specifically refer to the target products formed after graphite raw materials have been fully electrochemically exfoliated, usually consisting of 1 to 5 layers, with low density, and can be suspended to form a dispersion; this is common knowledge in the industry.

[0040] In this invention, the DC power supply positive terminal → positive electrode wire 13 → graphite electrode (anodic reaction) → electrolyte (ion migration) → counter electrode (cathode reaction) → negative electrode wire 14 → power supply negative terminal constitute a complete electron and ion conduction circuit.

[0041] In this invention, the electrolytic cell 1 includes an upper cylindrical section and a lower funnel section, connected together. The inner wall of the funnel section forms a 45° angle with its central axis, and its height-to-diameter ratio is 1:1.2-1:1.5 (the height-to-diameter ratio of the funnel section is the ratio of its height to its maximum inner diameter). The design of the funnel section facilitates the settling and enrichment of detached graphite fragments before they enter the separation and collection assembly.

[0042] Preferably, such as Figures 2-4 As shown, the graphite electrode device 10 includes an insulating mesh cylinder 10-1 and a conductive metal sheet 10-2; The lower end of the insulating mesh cylinder 10-1 is closed, and the upper end is open; the conductive metal sheet 10-2 is fixed to the upper part of the insulating mesh cylinder 10-1 by an insulating clamp 10-3; The graphite sheet 7 to be peeled is rolled into a cylindrical shape that runs through the top and bottom, and fixed to the inner wall of the insulating mesh cylinder 10-1 by the insulating clamp 10-3. The graphite sheet 7 is in contact with the conductive metal sheet 10-2, and the conductive metal sheet 10-2 is connected to the positive electrode wire 13.

[0043] In this invention, the center-to-center spacing of the mesh of the insulating mesh tube 10-1 is 1-5 mm, and the wall thickness is 0.3-1 mm. Both the insulating clamp 10-3 and the insulating mesh tube 10-1 are made of polytetrafluoroethylene (PTFE). The insulating clamp 10-3 contacts and fixes the graphite sheet 7 to the conductive metal sheet 10-2, allowing the graphite sheet 7 to be energized for electrochemical stripping. The center-to-center spacing of the mesh of the insulating mesh tube 10-1 is 1-5 mm, and the wall thickness is 0.3-1 mm. Both the insulating clamp 10-3 and the insulating mesh tube 10-1 are made of polytetrafluoroethylene (PTFE). The material of the graphite sheet 7 can be one of graphite foil, highly oriented pyrolytic graphite, natural flake graphite, graphite powder, activated carbon, artificial graphite, or expanded graphite. The graphite is pre-treated into sheets, and its thickness and width are adapted to the dimensions of the insulating mesh tube 10-1 in the graphite electrode device 10. It is then bent into a ring shape by a subsequent winding device 9 for feeding, in order to achieve continuous electrolysis.

[0044] Preferably, such as Figure 5 As shown, the counter electrode device 11 includes a platinum sheet 11-1, which is rolled into a cylindrical shape that runs through the top and bottom and is fixed by the fixing buckles 11-2 at the top and bottom ends; the platinum sheet 11-1 is connected to the negative terminal of the DC power supply through the negative electrode wire 14.

[0045] In this invention, graduation lines for indicating the curling diameter of platinum sheet 11-1 are equally spaced on the inner surface of the platinum sheet 11-1; the graduation lines can be laser etched, with a length of 5 mm and a width of 0.1 mm; the color is deepened by slight oxidation treatment for easy observation.

[0046] In this invention, the thickness of the platinum sheet 11-1 is 0.1-0.5 mm; the diameter of the rolled platinum sheet 11-1 is adjustable. By adjusting the movable end of the platinum sheet 11-1, the scale line on the platinum sheet 11-1 is made to coincide with the long reference line set on the fixing buckle 11-2, thus changing the diameter of the platinum sheet 11-1, thereby adjusting the distance between the graphite electrode device 10 and the counter electrode device 11. The insertion of the platinum sheet 11-1 is as follows: Figure 6 As shown.

[0047] Preferably, such as Figures 7-9 As shown, the continuous feeding assembly also includes a curling device 9 for curling the graphite sheet 7 into a cylindrical shape. The curling device 9 includes a coaxial outer curling cylinder 9-1 and an inner curling cylinder 9-2 arranged inside and outside the outer curling cylinder 9-1, as well as an outer curling pulley 9-3 installed outside the outer curling cylinder 9-1 and an inner curling pulley 9-4 installed inside the inner curling cylinder 9-2. An annular curled cavity for accommodating graphite sheet 7 is left between the curled outer cylinder 9-1 and the curled inner cylinder 9-2; The axes of the outer coiled pulley 9-3 and the inner coiled pulley 9-3 are vertical. The outer coiled pulley 9-3 and the inner coiled pulley 9-4 are arranged in pairs to form a coiled pulley group. The two are respectively connected to the corresponding pulley drive assembly, and the rotation is achieved by the pulley drive assembly, as well as the adjustment of the distance between the outer traction pulley 8-3 and the inner traction pulley 8-4. Both the outer curling pulley 9-3 and the inner curling pulley 9-4 are in contact with the graphite sheet 7 inserted into the curling cavity. They rotate in opposite directions, driving the graphite sheet 7 to curl.

[0048] In this invention, the curling device 9 includes four curling pulley groups arranged symmetrically. The outer curling pulley 9-3 passes through the outer curling cylinder 9-1, and the inner curling pulley 9-4 passes through the inner curling cylinder 9-2, respectively contacting the outer and inner surfaces of the graphite sheet 7. The friction between the curling pulley groups and the graphite sheet 7 drives the graphite sheet 7 to move and applies a directional curling force. The tension on the graphite sheet 7 is affected by the distance between the inner curling pulley 9-4 and the outer curling pulley 9-3. Before curling, the graphite sheet 7 is elongated. Initially, the lower end of the graphite sheet 7 is curled and inserted into the curling cavity, while the upper two sides of the graphite sheet 7 are naturally open (not closed). The outer curling pulley 9-3 and the inner curling pulley 9-4 rotate under the action of their corresponding pulley drive components, causing the two sides of the graphite sheet 7 to move towards each other to achieve curling. Specifically, taking the clockwise curling of the right side of graphite sheet 7 as an example, the inner curling pulley 9-4 located on the inner wall of the right side of graphite sheet 7 rotates clockwise, and the outer curling pulley 9-3 located on the outer wall of the right side of graphite sheet 7 rotates counterclockwise, together providing a clockwise curling force for the right side of graphite sheet 7, thereby enabling the right side of graphite sheet 7 to curl clockwise; the counterclockwise curling of the left side of graphite sheet 7 is arranged in the same way.

[0049] Preferably, such as Figure 7 , 10 As shown in Figure 11, the continuous feeding assembly also includes a traction device 8 for pulling the rolled-up graphite sheet 7 into the insulating mesh cylinder 10-1. The traction device 8 includes a coaxial inner traction cylinder 8-2 and an outer traction cylinder 8-1 arranged inside and outside the cylinder, as well as an outer traction pulley 8-3 installed outside the outer traction cylinder 8-1 and an inner traction pulley 8-4 installed inside the inner traction cylinder 8-2. An annular traction cavity for accommodating graphite sheet 7 is provided between the outer traction cylinder 8-1 and the inner traction cylinder 8-2. The axes of the outer traction pulley 8-3 and the inner traction pulley 8-4 are horizontal. The outer traction pulley 8-3 and the inner traction pulley 8-4 are arranged in pairs to form a traction pulley group, and are respectively connected to the corresponding pulley drive assembly. The rotation is achieved by driving the pulley drive assembly, and the distance between the outer traction pulley 8-3 and the inner traction pulley 8-4 can be adjusted. Both the outer traction pulley 8-3 and the inner traction pulley 8-4 are in contact with the graphite sheet 7 inserted into the traction cavity. They rotate in opposite directions to pull the graphite sheet 7 downward.

[0050] In this invention, the traction device 8 includes four traction pulley groups arranged circumferentially at intervals; the outer traction pulley 8-3 passes through the outer traction cylinder 8-1, and the inner traction pulley 8-4 passes through the inner traction cylinder 8-2, and the two are in contact with the outer and inner surfaces of the graphite sheet 7, respectively; the inner traction pulley 8-4 located on the inner surface of the graphite sheet 7 and the outer traction pulley 8-3 located on the outer surface of the graphite sheet 7 rotate synchronously in opposite directions, while providing a downward frictional force to the graphite sheet 7, thus tractioning the graphite sheet 7 to move downward.

[0051] In this invention, the inner coil 9-2, the outer coil 9-1, the inner traction coil 8-2, and the outer traction coil 8-1 are all made of insulating material, specifically polytetrafluoroethylene (PTFE). Each pulley (including the inner coil pulley 9-4, the outer coil pulley 9-3, the inner traction pulley 8-4, and the outer traction pulley 8-3) is a metal part (which may be made of aluminum alloy), completely covered with an adhesive layer (which may be made of silicone rubber). The adhesive layer contains a fiber optic strain sensor; the surface of the adhesive layer has a diamond-shaped pattern with a pattern depth of 0.3-1 mm and a pattern spacing of 0.5-2 mm.

[0052] Preferably, such as Figure 13 and Figure 14 As shown, the pulley drive assembly includes a pulley telescopic drive component 15 and a rotary drive motor 16-1. The pulley telescopic drive component 15 includes a linear drive mechanism, a bracket 15-3 and a guide rail 15-4. The driving end of the linear drive mechanism is connected to the bracket 15-3, the bracket 15-3 is adapted to the guide rail 15-4, and the linear drive mechanism can drive the bracket 15-3 to move linearly along the guide rail 15-4. The rotary drive motor 16-1 is connected to the corresponding pulley via a universal telescopic coupling 16-2, and both the rotary drive motor 16-1 and the corresponding pulley are mounted on the bracket 15-3.

[0053] In this invention, the pulley telescopic drive component 15 drives the rotary drive motor 16-1 on the bracket 15-3 and the corresponding pulley to move linearly along the guide rail 15-4, thereby changing the distance between two pulleys in the traction pulley group or the coiling pulley group. The rotary drive motor 16-1 drives the corresponding pulley to rotate.

[0054] In this invention, the linear drive mechanism includes a linear drive motor 15-1 and a ball screw pair 15-2, which is a mature existing structure. The linear drive mechanism drives the corresponding pulley and the rotary drive motor 16-1 to move linearly through the bracket 15-3. The length direction of the guide rail 15-4 is consistent with the movement direction of the corresponding pulley. The tension of the corresponding pulley is detected by the fiber optic strain sensor. Based on the tension and the voltage and temperature signals of the electrolytic cell 1, the linear drive mechanism drives the bracket 15-3 to move along the guide rail 15-4, thereby adjusting the distance between the inner and outer pulleys in the same pulley group.

[0055] In this invention, the rotary drive motor 16-1 and the universal telescopic coupling 16-2 constitute the pulley rotation drive component 16, which drives the corresponding pulleys to rotate, and the inner and outer pulleys of the pair rotate synchronously in opposite directions; through the rotation of the pair of pulley groups, the graphite sheet 7 is provided with the corresponding curling force or traction force.

[0056] Preferably, the separation and collection assembly includes a discharge centrifugal pump 6 and a cyclone separator 12. The discharge centrifugal pump 6 is located on the discharge pipe 5, the outlet of the discharge pipe 5 is connected to the inlet of the cyclone separator 12, and the top overflow port of the cyclone separator 12 is connected to the continuous feeding assembly.

[0057] In this invention, the hydrocyclone separator 12 is used to separate the electrolyte containing graphene products after electrolysis from the incompletely peeled graphite fragments (with a particle size smaller than the mesh size of the insulating mesh cylinder 10-1). The electrolyte containing graphene products flows out from the top, and the graphite fragments flow out from the bottom. The top outlet of the hydrocyclone separator 12 is connected to the inlet of the graphene and electrolyte treatment device 18 through a pipe. The electrolyte outlet of the graphene and electrolyte treatment device 18 is connected to the continuous feeding assembly through a pipe. After the graphene and electrolyte treatment device 18 performs post-treatment, the electrolyte containing graphene products is used to obtain a graphene product without impurities and a purified electrolyte. The electrolyte enters the continuous feeding assembly (specifically, it enters the storage tank 2).

[0058] Preferably, the continuous feeding assembly includes a feeding centrifugal pump 3 and a storage tank 2. The feeding centrifugal pump 3 is installed on the feeding pipe 4, and the inlet end of the feeding pipe 4 is connected to the storage tank 2. The storage tank 2 stores electrolyte. The storage tank 2 is connected to the top overflow port of the hydrocyclone separator 12.

[0059] In this invention, the continuous feeding component can realize continuous automatic feeding. The feeding speed of the traction device 8 is adjusted by detecting the voltage fluctuation and reaction temperature in the electrolytic cell 1. The initial speed can be set to 0.1-50 mm / min according to the peeling conditions.

[0060] Preferably, the system further includes a controller, a voltage sensor 17, and a temperature sensor; like Figure 12As shown, a voltage sensor 17 is connected in parallel on the wire connecting the annular graphite electrode device 10 and the counter electrode device 11 to collect the working voltage in the circuit in real time; a temperature sensor is set inside the electrolytic cell 1 to detect the real-time temperature of the electrolyte. The controller is connected to the voltage sensor 17, temperature sensor, fiber optic strain sensor, and each pulley drive assembly, specifically to the linear drive motor 15-1 and the rotary drive motor 16-1.

[0061] In this invention, the voltage sensor 17 can be a high-precision DC voltage sensor, adapted to a stripping voltage range of 1-60V; the voltage sensor 17 transmits the collected voltage data to the controller (specifically, a PID controller), the controller compares the set stripping voltage (such as 10V in Example 1) with the real-time operating voltage, and determines whether there are voltage fluctuations (such as voltage increases or decreases caused by changes in local stripping efficiency), providing a basis for subsequent feeding speed adjustment.

[0062] In this invention, the temperature sensor is preferably located near the electrode area or the electrolyte circulation path to avoid interfering with graphite stripping and fragment sedimentation. The temperature sensor can be a platinum resistance temperature sensor or a thermocouple, adapted to the electrolyte reaction temperature range. The temperature sensor transmits the detected temperature signal to the controller. The controller compares the detected temperature signal with the suitable temperature range for electrochemical stripping (e.g., room temperature to 60°C, to avoid electrolyte evaporation or graphite oxidation due to high temperature) to identify abnormal temperature changes (e.g., temperature rise caused by local energy concentration), which serves as another key parameter for adjusting the feeding rate.

[0063] In this invention, an optical fiber strain sensor is used to monitor the tension generated by the corresponding pulley on the graphite sheet 7 in real time, ensuring that the tension is stable within a suitable range of 0.5-2N. This range is suitable for the tensile strength of the sheet graphite material: if the tension is too high, it will easily lead to material breakage; if it is too low, it will easily slip. This invention also uses an optical fiber strain sensor to determine whether the graphite sheet 7 is wrinkled. First, a strain reference is established when the graphite sheet 7 is flat. During real-time monitoring, the local non-uniform deformation caused by wrinkles will cause abrupt changes in the optical fiber strain (such as curve fluctuations or array reversal). If the strain abnormally exceeds the normal threshold, it is determined that the graphite sheet 7 has wrinkled.

[0064] In this invention, when the controller receives a signal of voltage fluctuation or temperature change, it sends a speed adjustment command to the rotary drive motor 16-1 to adjust the output speed of the rotary drive motor 16-1, thereby changing the synchronous reverse rotation speed of the traction pulley group. The controller receives the tension signal sent by the fiber optic strain sensor and, based on the tension, uses the linear drive motor 15-1 to adjust the distance between the two pulleys in the traction pulley group and the coiling pulley group. Since the graphite sheet 7 is placed in the insulating mesh cylinder 10-1 from top to bottom through the insulating clamp 10-3 via the traction device 8, the rotation speed of the traction pulley group directly determines the downward movement speed of the graphite sheet 7 (i.e., the feeding speed), ultimately achieving adaptive adjustment of the feeding speed within the initially set range of 0.1-50 mm / min, ensuring stable peeling efficiency and product quality.

[0065] Example 2 A method for the continuous preparation of graphene by electrochemical exfoliation, the method comprising: Step 1: Assemble the system for continuous preparation of graphene by electrochemical exfoliation as described above. Connect the graphite electrode device 10 and the counter electrode device 11 to two sets of wires with opposite polarities of DC power supply, respectively. The graphite electrode device 10 is connected to the positive electrode wire 13 as the working electrode, and the counter electrode device 11 is connected to the negative electrode wire 14 as the auxiliary electrode. Step 2: Select a suitable electrolyte and add it into the storage tank 2 of the electrolytic cell 1 and the continuous feeding assembly, respectively. Step 3: Insert the lower end of the graphite sheet 7 into the curling cavity of the curling device 9, and use the curling device 9 to curl the lower end of the graphite sheet 7 into a cylindrical shape (so that the graphite sheet 7 can smoothly enter the insulating mesh cylinder 10-1). After curling, the graphite sheet 7 enters the traction device 8: Initially, the lower end of the graphite sheet 7 is curled and inserted into the curling cavity. The gap between the outer curling pulley 9-3 and the inner curling pulley 9-4 in the preset curling pulley group (related to the curling radius) is set. The curling pulley group is started to curl the graphite sheet 7. During the curling process, the fiber optic strain sensor detects the strain of the graphite sheet 7 in real time. If the graphite sheet 7 wrinkles, the controller controls and adjusts the gap between the inner curling pulley 9-4 and the outer curling pulley 9-3 to correct the curling radius so that the curling radius of the graphite sheet 7 matches the inner diameter of the insulating mesh cylinder 10-1. Step 4: Activate the traction device 8 to pull the graphite sheet 7, which has been curled by the curling device 9, into the insulating mesh cylinder 10-1 of the graphite electrode device 10. Adjust the feeding speed according to the voltage fluctuations and temperature changes in the electrolytic cell 1, and adjust the traction pulley spacing according to the tension of the graphite sheet 7. The voltage fluctuations and reaction temperature changes in electrolytic cell 1 are detected to determine the peeling efficiency. If an increase in the working voltage (insufficient local peeling) is detected and exceeds the set peeling voltage, or if a real-time temperature increase in electrolytic cell 1 (local energy concentration) exceeds the set temperature range, the controller reduces the feeding speed of graphite sheets 7 by controlling the pulley drive component corresponding to the traction pulley group (reducing the pulley speed), thereby extending the graphite material peeling time. Conversely, the controller increases the feeding speed of graphite sheets 7 by controlling the pulley drive component corresponding to the traction pulley group (increasing the pulley speed). At the same time, the fiber optic strain sensors in each pulley detect the tension of graphite sheets 7 and send it to the controller. The controller compares the detected tension value with the set value. If the tension value exceeds the set value, the distance between the inner traction pulley 8-4 and the outer traction pulley 8-3 is increased through the linear drive mechanism; otherwise, the distance between the inner traction pulley 8-4 and the outer traction pulley 8-3 is decreased. Step 5: The graphite sheet 7 comes into contact with the conductive metal sheet 10-2 in the graphite electrode device 10 and is immersed in the electrolyte of the electrolytic cell 1; the circuit is turned on to electrochemically peel off the graphite sheet 7; the peeling voltage and peeling time are set according to the characteristics of the graphite material and the requirements of the target product. Step Six: Collect the mixed slurry generated from the peeling process in electrolytic cell 1. The mixed slurry includes incompletely peeled graphite fragments and an electrolyte containing suspended graphene products. The peeled graphite fragments collect along electrolytic cell 1, and the graphene products are suspended in the electrolyte to form a dispersion, constituting the mixed slurry. The peeled graphite fragments in electrolytic cell 1 collect downwards along the funnel section of electrolytic cell 1 under the action of gravity, forming a lower layer of concentrated product that is enriched at the bottom outlet, preparing for subsequent transport to the hydrocyclone separator 12. The peeled graphene products remain suspended under the convection of the electrolyte, forming an upper layer of dispersion, which slowly flows with the electrolyte to the bottom outlet and deposits on top of the lower layer of concentrated product. The two are initially separated but not completely separated, forming a mixed slurry. Step 7: The mixed slurry is conveyed to the hydrocyclone separator 12 to separate the incompletely peeled graphite fragments at the bottom from the dispersion of graphene-containing products and electrolyte at the top.

[0066] In this invention, after the mixed slurry level reaches the standard, it is transported to the hydrocyclone separator 12 by the discharge centrifugal pump 6; after the mixed slurry level at the bottom of the electrolytic cell 1 is higher than the set level, the discharge centrifugal pump 6 is started to transport the mixed slurry to the hydrocyclone separator 12, providing power for subsequent efficient separation, while avoiding secondary agglomeration or deterioration caused by long-term retention of the mixed slurry in the electrolytic cell 1. The hydrocyclone separator 12 separates the incompletely peeled graphite fragments at the bottom (lower layer concentrated product) from the graphene product and electrolyte dispersion at the top (upper layer dispersed product): the mixed slurry enters the hydrocyclone separator 12, and under the action of centrifugal force, the lower layer concentrated product is discharged from the bottom of the hydrocyclone separator 12, and the upper layer dispersed product is discharged from the top of the hydrocyclone separator 12. Specifically, the incompletely peeled graphite fragments, due to their large mass, are thrown against the inner wall of the hydrocyclone 12 and flow downwards along the inner wall, eventually being discharged from the outlet at the bottom of the hydrocyclone 12, becoming the lower layer concentrated product (after post-processing such as filtration, washing, and drying, it is pressed again into graphite sheets 7 for recycling as peeling raw materials); while the graphene product, due to its light mass and good dispersibility, moves upwards with the center of the vortex to the top of the hydrocyclone 12 and is discharged from the overflow outlet at the top of the hydrocyclone 12, becoming the upper layer dispersed product (a mixture of graphene product and electrolyte). After the graphene product in the upper dispersed product is separated by filtration, the obtained electrolyte is introduced into the storage tank 2 for reuse.

[0067] In this invention, the feeding speed of graphite sheet 7 is achieved by adjusting the rotation speed of the rotary drive motor 16-1 of the traction pulley group. The controller dynamically matches the rotation speed to ensure that the outer traction pulley 8-3 and the inner traction pulley 8-4 rotate synchronously in opposite directions (rotation speed deviation ≤ ±1%), thereby stabilizing the feeding speed of graphite sheet 7 within the set range to meet voltage and temperature requirements. The initial speed of the rotary drive motor 16-1 of the traction device 8 can be set to 0.1-50 mm / min according to the peeling conditions such as the thickness of graphite sheet 7 and the type of electrolyte (e.g., the initial speed is set to 1 mm / min when the thickness of graphite sheet 7 is 0.8 mm, and to 10 mm / min when the thickness of graphite foil is 0.2 mm).

[0068] In this invention, the graphite sheet 7 is elongated. Initially, the lower end is manually inserted into the curling cavity of the curling device 9, and then continuous feeding is achieved through the curling device 9 and the traction device 8. The electrolyte in the electrolytic cell 1 is continuously fed by the storage tank 2: the upper layer of electrolyte containing a small amount of graphene is separated by the hydrocyclone 12, and after post-processing by filtration and other means, the regenerated electrolyte is added back to the electrolyte storage tank 2. A liquid level sensor (which can be an ultrasonic sensor) is installed in the electrolytic cell 1. When the liquid level in the electrolytic cell 1 is detected to be lower than the set minimum threshold, the feeding centrifugal pump 3 is started to transport the electrolyte in the storage tank 2 to the electrolytic cell 1. When the liquid level in the electrolytic cell 1 is detected to be higher than the set maximum threshold, the feeding centrifugal pump 3 is turned off to stop the replenishment. The electrolyte volume in electrolytic cell 1 is 60%-80% of the total volume. The electrolyte concentration is monitored by a conductivity sensor and is usually between 0.5-2 mol / L. The operating voltage of electrolytic cell 1 (the stripping voltage measured by the parallel voltage sensor 7 of the positive and negative electrode bus) is 1-60V. The initial reaction temperature (detected by a temperature sensor) is room temperature. As the reaction proceeds, the temperature rises and may even reach 60℃ (not exceeding 60℃).

[0069] In this invention, the curling radius of the graphite sheet 7 is matched with the inner diameter of the insulating mesh tube 10-1 in the graphite electrode device 10 (the hollow spacing of the insulating mesh is 1-5 mm, preferably 3 mm). In the early stage, the spacing between the inner curling pulley 9-4 and the outer curling pulley 9-3 is adjusted to fix the curling radius (the spacing is positively correlated with the curling radius), ensuring that the curled graphite can smoothly enter the insulating mesh tube 10-1.

[0070] In this invention, the curling speed of the graphite sheet 7 must be synchronized with the feeding speed of the traction device 8 (speed deviation ≤ ±2%) to avoid problems such as excessive traction causing the graphite sheet 7 to stretch or excessive curling causing the graphite sheet 7 to accumulate. Based on this, the curling device 9 and the traction device 8 are connected to the same controller to achieve speed linkage adjustment, ensuring that the curling speed and traction speed are matched in real time. For example, when the traction speed is set to 1 mm / min, the curling speed is synchronously set to 1 mm / min.

[0071] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0072] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for the continuous preparation of graphene by electrochemical exfoliation, characterized in that, Includes a stripping assembly, a separation and collection assembly, and a continuous feeding assembly; The stripping assembly includes an electrolytic cell, a graphite electrode device, and a counter electrode device. The electrolytic cell is filled with an electrolyte. The graphite electrode device and the counter electrode device are both immersed in the electrolyte. The graphite electrode device is coaxially disposed inside the counter electrode device. The graphite electrode device is connected to the positive terminal of a DC power supply through a positive electrode wire, and the counter electrode device is connected to the negative terminal of a DC power supply through a negative electrode wire. The inlet of the separation and collection component is connected to the outlet at the bottom of the electrolytic cell via an outlet pipe; The continuous feeding assembly is used to continuously replenish the electrolyte in the electrolytic cell and to continuously supply graphite sheets to the graphite electrode device.

2. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 1, characterized in that, The graphite electrode device includes an insulating mesh tube, a conductive metal sheet, and an insulating clamp. The lower end of the insulating mesh tube is closed, and the upper end is open; the conductive metal sheet is fixed to the upper part of the insulating mesh tube by an insulating clamp, and the conductive metal sheet is used to connect to the positive electrode wire. The graphite sheet to be peeled is rolled into a cylindrical shape that runs from top to bottom, and fixed to the inner wall of the insulating mesh cylinder by an insulating clamp, with the graphite sheet in contact with the conductive metal sheet.

3. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 2, characterized in that, The counter electrode device includes a platinum sheet, which is rolled into a cylindrical shape that runs vertically through the top and bottom and is fixed by fasteners at the top and bottom; the platinum sheet is connected to the negative electrode wire.

4. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 2 or 3, characterized in that, The continuous feeding assembly also includes a curling device, which includes a coaxial and innerly arranged outer curling cylinder and an inner curling cylinder, as well as an outer curling pulley installed outside the outer curling cylinder and an inner curling pulley installed inside the inner curling cylinder. An annular curled cavity for accommodating graphite sheets is left between the curled outer cylinder and the curled inner cylinder. The axes of the outer and inner coiled pulleys are vertical. The outer and inner coiled pulleys are arranged in pairs to form a coiled pulley group. The two are respectively connected to the corresponding pulley drive components. The rotation is achieved by driving the pulley drive components, and the distance between the outer and inner traction pulleys can be adjusted. Both the outer and inner curling pulleys are in contact with the graphite sheet inserted into the curling cavity, and they rotate in opposite directions to drive the graphite sheet to curl.

5. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 4, characterized in that, The continuous feeding assembly also includes a traction device for drawing the rolled-up graphite sheet into the insulating mesh cylinder. The traction device includes a coaxial inner traction cylinder and an outer traction cylinder arranged inside and outside the outer traction cylinder, as well as an outer traction pulley installed outside the outer traction cylinder and an inner traction pulley installed inside the inner traction cylinder. An annular traction cavity for accommodating graphite sheets is provided between the outer traction cylinder and the inner traction cylinder. The axes of the outer traction pulley and the inner traction pulley are horizontal. The outer traction pulley and the inner traction pulley are arranged in pairs to form a traction pulley group, and are respectively connected to the corresponding pulley drive assembly. The rotation is achieved by driving the pulley drive assembly, and the distance between the outer traction pulley and the inner traction pulley can be adjusted. Both the outer and inner traction pulleys are in contact with the graphite sheet inserted into the traction cavity, and they rotate in opposite directions to pull the graphite sheet downward.

6. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 5, characterized in that, Each pulley is made of metal and is completely covered with a rubber layer, which contains a fiber optic strain sensor.

7. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 6, characterized in that, The separation and collection assembly includes a discharge centrifugal pump and a hydrocyclone separator. The discharge centrifugal pump is located on the discharge pipe, the outlet of the discharge pipe is connected to the inlet of the hydrocyclone separator, and the top overflow port of the hydrocyclone separator is connected to the storage tank of the continuous feeding assembly.

8. The system for continuous preparation of graphene by electrochemical exfoliation according to claim 7, characterized in that, The system also includes a controller, a voltage sensor, a temperature sensor, and a fiber optic strain sensor; The voltage sensor is connected in parallel to the wire connecting the graphite electrode device and the counter electrode device to collect the circuit operating voltage; the temperature sensor is located inside the electrolytic cell to detect the electrolyte temperature; the fiber optic strain sensor is located in the adhesive layer of the pulley of the continuous feeding assembly to monitor the tension of the graphite sheet. The controller is connected to the voltage sensor, temperature sensor, fiber optic strain sensor, and each pulley drive assembly of the continuous feeding assembly.

9. A method for the continuous preparation of graphene by electrochemical exfoliation, characterized in that, Includes the following steps: Assemble the system for continuous preparation of graphene by electrochemical exfoliation as described in claim 8; The electrolyte is added separately to the storage tanks of the electrolytic cell and the continuous feeding assembly; Insert the lower end of the graphite sheet into the curling cavity of the curling device, and use the curling device to curl the lower end of the graphite sheet into a cylindrical shape; Start the traction device to pull the rolled graphite sheet into the insulating mesh tube of the graphite electrode device. Adjust the graphite sheet feeding speed according to the voltage fluctuation and temperature change in the electrolytic cell, and adjust the traction pulley spacing according to the graphite sheet tension. The graphite sheet is immersed in the electrolyte of the electrolytic cell, and the circuit is connected to perform electrochemical stripping of the graphite sheet. Collect the mixed slurry generated during the stripping process in the electrolytic cell. The mixed slurry includes incompletely stripped graphite fragments and an electrolyte containing suspended graphene products. The mixed slurry is fed to a hydrocyclone separator, where graphite fragments at the bottom and a dispersion of graphene-containing products and electrolyte at the top are separated.

10. The method for continuous preparation of graphene by electrochemical exfoliation as described in claim 9, characterized in that, The method for adjusting the graphite sheet feeding speed based on voltage fluctuations and temperature changes within the electrolytic cell is as follows: The controller detects voltage fluctuations and reaction temperature changes in the electrolytic cell to determine the peeling efficiency. If the operating voltage rises and exceeds the set peeling voltage, or the real-time temperature in the electrolytic cell rises and exceeds the set temperature range, the controller will reduce the feeding speed of the graphite sheets and extend the graphite material peeling time by controlling the pulley drive component corresponding to the traction pulley group. Conversely, it will control the pulley drive component corresponding to the traction pulley group to increase the feeding speed of the graphite sheets.

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