Method and device for macroscopically preparing graphene by utilizing pulse discharge

Abstract

The invention relates to a method and a device for macroscopically preparing graphene by utilizing pulse discharge. The device for macroscopically preparing graphene by utilizing pulse discharge comprises an upper discharge device, a clamping device, an upper graphite electrode, a lower discharge capacitor, a lower graphite electrode, a driving motor, a pulse power supply, a control computer and an ultrasonic device. The invention provides the method and the device for preparing the graphene in the macroscopic quantity by utilizing the pulse discharge, which can overcome the defects in the prior art, enrich the product structure of the electrochemical stripping graphene, expand the preparation condition and simultaneously realize the assembly line macroscopic quantity preparation.

Description

Technical Field

[0001] The invention relates to the field of graphene manufacturing and mechanical processing, and in particular to a method and a device for preparing graphene in large quantities by using pulse discharge. Background Art

[0002] Graphene is a two-dimensional material with a hexagonal honeycomb grid structure, which has a wide range of applications in energy, medical treatment and other fields. As a special layered material, it is usually composed of a single layer or a few layers of carbon atoms. Common graphene preparation methods include top-down and bottom-up methods, including chemical vapor deposition, pyrolysis, chemical synthesis, electrochemical stripping, etc. In the electrochemical stripping method, laboratory devices such as beakers and foil are usually used as experimental devices. The equipment process is complicated, and it is obviously out of touch with the actual industry, making it difficult to scale up industrially. At the same time, the prepared graphene has a single structure, lacks special structures such as holes and vortices, and its application potential is insufficient. Summary of the invention

[0003] In view of the above problems, the present invention proposes a method and device for preparing graphene in large quantities by pulse discharge. The present invention can overcome the shortcomings of the prior art, enrich the product structure of electrochemically exfoliated graphene, expand the preparation conditions and realize assembly line large-scale preparation.

[0004] To achieve the above object, the present invention provides the following technical solutions: A device for preparing graphene in large quantities by pulse discharge, comprising: The upper discharge device is connected to the pulse power supply through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The clamping device is composed of more than two rectangular metal bars, and there are through holes in the middle or on both sides of the upper part of the rectangular metal bars, and the separation and compression of the rectangular metal bars are achieved by screws. There is an upward metal strip on the upper surface of the middle part of one of the rectangular metal bars, which is used to be fixed in the upper discharge device knob; The upper graphite electrode is one of a graphite rod and a graphite foil. When the upper graphite electrode uses a graphite rod, it is directly fixed in the knob of the upper discharge device. When the upper graphite electrode uses a graphite foil, the graphite foil is neatly arranged in the gap between the graphite foil and the rectangular metal strip, and the rectangular metal strip is tightened with a screw to fix the upper graphite electrode. The lower discharge capacitor is made of conductive metal or graphite, and its length, width and height are all greater than those of the lower graphite electrode, and smaller than those of the ultrasonic device. The lower discharge capacitor is connected to the pulse power supply through a wire, and is connected to the two poles of the pulse power supply with the upper discharge device respectively; The lower graphite electrode is composed of a graphite rod or a single graphite foil or multiple graphite foils; when the lower graphite electrode is a graphite rod or a single graphite foil, it is directly placed on the lower discharge container, and its upper surface area is larger than the lower surface area of ​​the lower graphite electrode to ensure discharge between the two electrodes; when the lower graphite electrode is multiple graphite foils, a clamping device composed of a rectangular metal bar and screws is selected to vertically clamp the multiple graphite foils in the clamping device and place them in the lower discharge container, at which time the lower graphite electrode and the upper graphite electrode are arranged crosswise; The drive motor is rigidly connected to the upper discharge device and is used to drive the upper discharge device to move in both translational and longitudinal directions, and is controlled by a control computer. Translational movement is a circular arc reciprocating motion with a range of 0~±10cm, which is used to make the discharge position more uniform; longitudinal movement is the discharge control process, and the control computer controls the drive motor to move longitudinally to ensure that the upper graphite electrode and the lower graphite electrode are within the working distance; The pulse power supply has two electrodes connected to the upper discharge device and the lower discharge capacitor respectively. The positive and negative polarities of the electrodes are adjustable and controlled by the control computer signal. When connected to 380V three-phase electricity, it can provide square wave pulse discharge. The control computer is used by the user to set parameters on the screen. The settable parameters include pulse width, pulse interval, current, voltage, gap, tool lift distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor and outputs discharge control signals to the pulse power supply according to the set values; The ultrasonic device includes an ultrasonic coolant and an ultrasonic vibrator. The ultrasonic device is an optional accessory. When the accessory is selected, its length, width and height are all greater than the lower discharge capacitor. The ultrasonic coolant is located inside the ultrasonic device and is usually tap water. The liquid level of the ultrasonic coolant is lower than the edge of the lower discharge capacitor to prevent the coolant from pouring in. The ultrasonic vibrator is located inside the ultrasonic device and is usually 1 to 6. The control is carried out according to the known method in the field, and the power supply controls the start and end of the ultrasonic assistance. The total ultrasonic power is 60 to 360 W.

[0005] As a further technical solution of the present invention, it also includes a circulation device, which is composed of a water pipe, a water pump and a circulation container. Holes are opened on both sides of the lower discharge capacitor and are sealed and connected with the water pipe to achieve the purpose of circulating electrolyte. When the circulation device is not selected, the electrolyte is located inside the lower discharge capacitor. The water pipe is composed of segments, and the water pump has a water inlet and a water outlet when it is connected to the power supply. The lower discharge capacitor and the circulation container are connected by a water pipe to guide the electrolyte in the lower discharge capacitor to the circulation container. The lower discharge capacitor and the water pump are connected by a water pipe, which is the water outlet of the water pump. The water pump and the circulation container are connected by a water pipe, which is the water inlet of the water pump. In this way, the electrolyte is pumped from the circulation container through the water pipe into the lower discharge capacitor by the water pump, submerges the lower graphite electrode, and then flows into the circulation container through the water pipe on the other side. The circulation container is located lower than the lower discharge capacitor, and liquid discharge is achieved by gravity.

[0006] Another object of the present invention is to provide a method for preparing graphene in large quantities by pulse discharge, the method being implemented based on the device for preparing graphene in large quantities by pulse discharge as claimed in claim 2, the method comprising the following steps: S100, ultrasonic cleaning of graphite electrodes; S200, fixing the upper graphite electrode to the upper discharge device; S300, placing the lower graphite electrode in the lower discharge container; S400, adding electrolyte into the discharge container so as to cover the electrodes; S600, connecting the upper discharge device and the lower discharge capacitor to a pulse power supply; S700, set the discharge parameters on the control computer and start the drive motor; S800, start the discharge power supply, and the upper discharge device descends to a specified height; S900, the upper and lower electrodes break through the electrolyte and start pulse discharge; S1000, when the discharge time is reached, the upper discharge device is raised; S1100, determine whether the output meets expectations; S1200, collection and dispersion of products.

[0007] As a further technical solution of the present invention, step S500 is further included between step S400 and step S600: turning on the ultrasonic device 13 and the circulation device.

[0008] As a further technical solution of the present invention, in step S100, ultrasonic cleaning of the graphite electrode means: fully cleaning the graphite electrode, first polishing the graphite electrode with sandpaper to avoid surface attachments and burrs from contaminating the product, fully ultrasonically cleaning the polished graphite electrode in deionized water and ethanol, and drying the electrode after cleaning; In step S200, fixing the upper graphite electrode to the upper discharge device means: using a clamp to fix the upper graphite electrode to the upper discharge device, the upper graphite electrode includes a graphite rod and a graphite foil electrode, so that it can move with the upper discharge device, and the fixing method adopts mechanical fixing, the graphite rod is directly clamped by the clamp, and a single or multiple graphite foils are clamped and fixed by the clamp in the vertical direction. After fixing, the upper discharge device and the upper graphite electrode can conduct electricity well; In step S300, placing the lower graphite electrode in the lower discharge container means: placing the lower graphite electrode in the conductive lower discharge container, ensuring close contact between the lower graphite electrode and the lower discharge container, and good conductivity, the lower graphite electrode includes a graphite rod and a graphite foil electrode, the graphite rod electrode keeps the cross section upward, a single graphite foil is horizontally placed at the bottom of the lower discharge container, ensuring that the area relative to the upper side is larger than the cross-sectional area of ​​the upper graphite electrode, and when multiple graphite foils are selected as the lower graphite electrodes, they are vertically fixed by a clamp and arranged alternately with the upper electrode.

[0009] In step S400, adding electrolyte to the discharge vessel so as to cover the electrode means: adding electrolyte to the lower discharge vessel, wherein the electrolyte is one of deionized water and a conductive electrolyte, and when a graphite rod or a single graphite foil is selected as the lower graphite electrode 5, the electrolyte covers the upper surface of the lower graphite electrode; wherein the conductive electrolyte is one of an inorganic salt electrolyte such as 0.001M-0.5M sodium sulfate, a surfactant electrolyte such as 0.001M-0.5M SDS, an acidic electrolyte such as 0.01M-1M sulfuric acid, etc. In step S500, turning on the ultrasonic device means adding an ultrasonic container with a built-in ultrasonic vibrator outside the lower discharge container 4, and controlling the device through a numerical control board to generate ultrasonic waves with a power of 60-360W to assist in sample dispersion; turning on the circulation device means adding a water inlet and a drain on both sides of the lower discharge container, and pumping and draining water through a water pump to realize the circulation of the electrolyte in the lower discharge container; In step S600, connecting the upper discharge device and the lower discharge capacitor to the pulse power supply means: connecting the upper discharge device and the lower discharge capacitor to the two poles of the pulse power supply with wires, respectively. To facilitate the taking of the lower discharge capacitor 4, the wires can be connected in the form of alligator clips; In step S700, the discharge parameters are set on the control computer, and starting the drive motor means: setting the pulse power supply discharge peak current to 0.1-63.8A, the discharge gap to 5-50μm, the pulse width to 5-100μs, the pulse interval to 5-100μs, the knife lift height to 0-10mm, the upper electrode or the lower electrode can be used as the anode and cathode, and the discharge time is set according to the production demand. The above discharge parameters are output to the pulse power supply and the drive motor, and the starter motor power supply is turned on. The drive motor is rigidly connected to the upper discharge device, and the upper discharge device is driven to perform a translational reciprocating motion in the horizontal direction, and the reciprocating motion range is 0~±10cm; In step S800, starting the discharge power supply and lowering the upper discharge device to a specified height means: starting the discharge on the control computer, at which time the longitudinal drive motor drives the upper discharge device to move downward according to the program, so that the lower end of the upper graphite electrode is immersed in the electrolyte, and after reaching the preset discharge gap, the longitudinal vertical movement stops; In step S900, the upper and lower electrodes break through the electrolyte to start pulse discharge, which means that after step S800, the equipment detects that the gap between the cathode and anode reaches the set parameters and starts pulse discharge, and the pulse discharge voltage is set from 10 to 200V according to the peak current, solution conductivity, gap and other parameters; during discharge, the pulse power supply performs square wave pulse discharge, the pulse width is the discharge duration, and the pulse interval is the discharge interval time; at the same time, the drive motor drives the upper electrode to perform longitudinal lifting and lowering reciprocating motion according to the lifting height setting while moving horizontally, so as to promote product slag discharge; In step S1000, reaching the discharge time to raise the upper discharge device means: reaching the discharge time set by the control computer, the pulse power supply stops discharging, and the driving motor drives the upper discharge device to be raised in the vertical direction; In step S1100, judging whether the output reaches the expectation means observing the suspended product in the electrolyte and the color of the electrolyte, roughly judging the output. If the expected output is not reached, resetting the discharge parameters and performing cyclic discharge. If the expected output is reached, proceeding to step S1200; In step S1200, the collection and dispersion of the product includes two steps: product collection and product dispersion. Product collection refers to collecting the electrolyte after the discharge is completed, and collecting graphene in a preset manner, wherein the preset manner includes suction filtration and differential centrifugation. The suction filtration is performed according to a method known in the art, and the differential centrifugation is performed at a speed of 10000-20000 rpm to obtain a centrifugal precipitate. DMF solution is added, and after dispersion and dissolution, the product is centrifuged again at a speed of 1000-5000 rpm to obtain a supernatant. The product is centrifuged again at a speed of 15000-20000 rpm to obtain a centrifugal precipitate. The product dispersion method includes drying the collected sample, freeze-drying it, and directly dissolving it in a DMF solution for retention.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method and device for large-scale preparation of graphene using pulse discharge, which can overcome the shortcomings of the prior art, enrich the product structure of electrochemical exfoliation of graphene, expand the preparation conditions and realize large-scale assembly line preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge provided by the present invention.

[0012] Figure 2 It is a schematic diagram of the structure of a clamping device 2 in a device for preparing graphene in large quantities using pulse discharge.

[0013] Figure 3 The present invention is a flowchart of a method for preparing graphene in large quantities using pulse discharge.

[0014] Figure 4 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 1.

[0015] Figure 5 This is a scanning electron microscope photograph of graphene exfoliated by discharge in Example 1.

[0016] Figure 6 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 2.

[0017] Figure 7 This is a scanning electron microscope photograph of the discharge-exfoliated graphene of Example 2.

[0018] Figure 8 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 3.

[0019] Fig. 9 This is a transmission electron microscope photograph of the discharge-exfoliated porous graphene of Example 3.

[0020] Fig.10 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 4.

[0021] Fig.11 This is a transmission electron microscope photograph of the discharge-exfoliated flash graphene of Example 4.

[0022] Fig.12 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 5.

[0023] Fig.13 This is a scanning electron microscope photograph of the discharge-exfoliated graphene of Example 5.

[0024] Fig.14 This is a schematic diagram of the structure of a device for macro-scale preparation of graphene using pulse discharge used in Example 6.

[0025] Fig.15 This is the X-ray diffraction test result of the graphite electrode graphite foil of Example 6.

[0026] Notes on figure numbers: 1-upper discharge device, 2-clamping device, 21-metal bar, 22-screw, 23-metal bar, 3-upper graphite electrode, 4-lower discharge container, 5-lower graphite electrode, 6-water pipe, 7-water pump, 8-circulation container, 9-electrolyte, 10-driving motor, 11-pulse power supply, 12-control computer, 13-ultrasonic device, 131-ultrasonic coolant, 132-ultrasonic vibrator. DETAILED DESCRIPTION

[0027] The technical solution of this patent is further described in detail below in conjunction with specific implementation methods.

[0028] See also Figure 1 and Figure 2 , as an embodiment of the present invention, a device for preparing graphene in large quantities by pulse discharge includes: The upper discharge device 1 is connected to the pulse power supply 11 through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The clamping device 2 is composed of more than two rectangular metal bars 21, and there are through holes in the middle or on both sides of the upper part of the rectangular metal bars 21. The separation and squeezing of the rectangular metal bars 21 are achieved by screws 22. There is an upward metal bar 23 on the upper surface of the middle part of one of the rectangular metal bars 21, which is used to be fixed in the knob of the upper discharge device 1; The upper graphite electrode 3 is one of a graphite rod and a graphite foil. When the upper graphite electrode 3 uses a graphite rod, it is directly fixed in the knob of the upper discharge device 1. When the upper graphite electrode 3 uses a graphite foil, the graphite foil is neatly arranged in the gap with the rectangular metal strip 21, and the rectangular metal strip 21 is tightened with a screw 22 to fix the upper graphite electrode 3; The lower discharge capacitor 4 is made of conductive metal or graphite, and its length, width and height are all greater than the lower graphite electrode 5, and smaller than the length, width and height of the ultrasonic device 13. The lower discharge capacitor 4 is connected to the pulse power supply 11 through a wire, and is connected to the two poles of the pulse power supply 11 with the upper discharge device 1 respectively; The lower graphite electrode 5 is composed of a graphite rod or a single graphite foil or a plurality of graphite foils; when the lower graphite electrode 5 is a graphite rod or a single graphite foil, it is directly placed on the lower discharge container 4, and its upper surface area is larger than the lower surface area of ​​the lower graphite electrode 5, so as to ensure discharge between the two electrodes; when the lower graphite electrode 5 is a plurality of graphite foils, a clamping device 2 composed of a rectangular metal bar and a screw is selected, and the plurality of graphite foils are vertically clamped in the clamping device 2 and placed in the lower discharge container 4, and the lower graphite electrode 5 is arranged crosswise with the upper graphite electrode 3; The driving motor 10 is rigidly connected to the upper discharge device 1, and is used to drive the upper discharge device 1 to move in two directions, translation and longitudinal, and is controlled by the control computer 12. The translation is a circular arc reciprocating motion, and the motion range is 0~±10cm, which is used to make the discharge position more uniform; the longitudinal movement is the discharge control process, and the control computer 12 controls the driving motor 10 to move longitudinally to ensure that the upper graphite electrode 3 and the lower graphite electrode 5 are within the working distance; The pulse power supply 11, whose two electrodes are respectively connected to the upper discharge device 1 and the lower discharge capacitor 4, has adjustable positive and negative polarities, and is controlled by a signal from a control computer 12. It is connected to 380V three-phase electricity and can provide square wave pulse discharge; The control computer 12 is used by the user to set parameters on the screen, and the settable parameters include pulse width, pulse interval, current, voltage, gap, knife lifting distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor 10 according to the set values, and outputs discharge control signals to the pulse power supply 11; The ultrasonic device 13 includes an ultrasonic coolant 131 and an ultrasonic vibrator 132. The ultrasonic device 13 is an optional accessory. When the accessory is selected, its length, width and height are all greater than the lower discharge container 4. The ultrasonic coolant 131 is located inside the ultrasonic device 13 and is usually tap water. The liquid level of the ultrasonic coolant 131 is lower than the edge of the lower discharge container 4 to prevent the coolant from pouring in. The ultrasonic vibrator 132 is located inside the ultrasonic device 13 and is usually 1 to 6. The control is carried out according to the known method in the field, and the power supply controls the start and end of the ultrasonic assistance. The total ultrasonic power is 60 to 360 W.

[0029] In the present embodiment, a circulation device is also included, which is composed of a water pipe 6, a water pump 7 and a circulation container 8. Holes are opened on both sides of the lower discharge container 4, which are sealed and connected with the water pipe 6 to achieve the purpose of circulating the electrolyte 9. When the circulation device is not selected, the electrolyte 9 is located inside the lower discharge container 4. The water pipe 6 is composed of three sections, and the water pump 7 has a water inlet and a water outlet when the power is turned on. The lower discharge container 4 is connected to the circulation container 8 through the water pipe 6, and the electrolyte 9 in the lower discharge container 4 is led out to the circulation container 8. The lower discharge container 4 is connected to the water pump 7 through the water pipe 6, which is the water outlet of the water pump 7. The water pump 7 is connected to the circulation container 8 through the water pipe 6, which is the water inlet of the water pump 7. In this way, the electrolyte 9 is pumped from the circulation container 8 through the water pipe 6 and into the lower discharge container 4 by the water pump 7, submerging the lower graphite electrode 5, and then flowing into the circulation container 8 through the water pipe 6 on the other side. The circulation container 8 is located lower than the lower discharge container 4, and liquid discharge is achieved by gravity.

[0030] The specific steps are: (1) Fix the cleaned graphite rod of the upper graphite electrode 3 in the knob of the upper discharge device 1, or fix the graphite foil of the upper graphite electrode 3 in the gap between the rectangular metal bars of the clamping device 2, tighten the screws, and fix the metal bar in the knob of the upper discharge device 1.

[0031] (2) Place the lower graphite electrode 5 in the lower discharge container 4.

[0032] When the circulation device is selected, the water pump 7 is turned on to pump the electrolyte 9 into the lower discharge container 4 so as to cover the upper surface of the lower graphite electrode 5 , thereby realizing the circulation of the electrolyte 9 .

[0033] When the circulation device is not selected, the electrolyte 9 is directly added into the lower discharge container 4 to cover the upper surface of the lower graphite electrode 5 .

[0034] (3) If the ultrasonic device 13 is selected, turn on the power of the ultrasonic device 13 and start the ultrasound. If it is not selected, skip this step.

[0035] (4) Turn on the control computer 12, connect the pulse power supply 11 and the power supply of the drive motor 10, and set the electrode polarity, pulse width, pulse interval, current, voltage, gap, knife lifting distance, and discharge time parameters; (5) Turn on the translation mode of the drive motor 10 and adjust it to a suitable translation speed through the controller; (6) Click on the control computer 12 to start discharging, and the control computer 12 sends the control command to the drive motor 10 and the pulse power supply 11. The drive motor 10 drives the upper discharge device 1 to descend to the specified discharge position. Pulse discharge is started between the upper graphite electrode 3 and the lower graphite electrode 5 according to the specified discharge parameters. According to the setting of the knife lifting height, the drive motor 10 drives the upper discharge device 1 to intermittently lift the knife.

[0036] (7) When the set discharge time is reached, the pulse power supply 11 stops discharging, and the upper discharge device 1 rises under the drive of the drive motor 10 and leaves the discharge position, completing the discharge machining process.

[0037] See also Figure 3 Another object of the present invention is to provide a method for preparing graphene in large quantities by pulse discharge, the method is implemented based on the device for preparing graphene in large quantities by pulse discharge as described in claim 2, and the method comprises the following steps: S100, ultrasonic cleaning of graphite electrodes; S200, fixing the upper graphite electrode 3 to the upper discharge device 1; S300, placing the lower graphite electrode 5 in the lower discharge container 4; S400, adding electrolyte 9 into the discharge container to cover the electrodes; S600, connecting the upper discharge device 1 and the lower discharge capacitor 4 to the pulse power supply 11; S700, setting discharge parameters on the control computer 12, and starting the drive motor 10; S800, starting the discharge power supply, and the upper discharge device 1 descends to a specified height; S900, the upper and lower electrodes break through the electrolyte 9 and start pulse discharge; S1000, when the discharge time is reached, the upper discharge device 1 is raised; S1100, determine whether the output meets expectations; S1200, collection and dispersion of products.

[0038] In this embodiment, step S500 is further included between step S400 and step S600: turning on the ultrasonic device 13 and the circulation device.

[0039] In this embodiment, in step S100, ultrasonic cleaning of the graphite electrode means: fully cleaning the graphite electrode, firstly polishing the graphite electrode with sandpaper to avoid surface attachments and burrs from contaminating the product, fully ultrasonic cleaning the polished graphite electrode in deionized water and ethanol, and drying the electrode after cleaning; In step S200, fixing the upper graphite electrode 3 to the upper discharge device 1 means: using a clamp to fix the upper graphite electrode 3 to the upper discharge device 1, the upper graphite electrode 3 includes a graphite rod and a graphite foil electrode, so that it can move with the upper discharge device 1, and the fixing method adopts mechanical fixing, the graphite rod is directly clamped by the clamp, and a single or multiple graphite foils are clamped and fixed by the clamp in the vertical direction. After fixing, the upper discharge device 1 and the upper graphite electrode 3 can conduct electricity well; In step S300, placing the lower graphite electrode 5 in the lower discharge container 4 means: placing the lower graphite electrode 5 in the conductive lower discharge container 4, ensuring that the lower graphite electrode 5 and the lower discharge container 4 are in close contact and can conduct electricity well, the lower graphite electrode 5 includes a graphite rod and a graphite foil electrode, the graphite rod electrode keeps the cross section upward, and a single graphite foil is horizontally placed at the bottom of the lower discharge container 4, ensuring that the area relative to the top is larger than the cross-sectional area of ​​the upper graphite electrode 3, and when multiple graphite foils are selected as the lower graphite electrodes 5, they are vertically fixed by a clamp and arranged alternately with the upper electrodes.

[0040] In step S400, adding electrolyte 9 to the discharge vessel so as to cover the electrodes means: adding electrolyte 9 to the lower discharge vessel 4, wherein the electrolyte is one of deionized water and a conductive electrolyte, and when a graphite rod or a single graphite foil is selected as the lower graphite electrode 5, the electrolyte 9 covers the upper surface of the lower graphite electrode 5; wherein the conductive electrolyte is one of an inorganic salt electrolyte such as 0.001M-0.5M sodium sulfate, a surfactant electrolyte such as 0.001M-0.5M SDS, an acidic electrolyte such as 0.01M-1M sulfuric acid, etc. In step S500, turning on the ultrasonic device 13 means adding an ultrasonic container around the lower discharge container 4, which has an ultrasonic vibrator 132 built therein, and controlling the device through a numerical control board to generate ultrasonic waves with a power of 60-360W to assist in sample dispersion; turning on the circulation device means adding a water inlet and a drain on both sides of the lower discharge container 4, and pumping and draining water through a water pump 7 to realize the circulation of the electrolyte 9 in the lower discharge container 4; In step S600, connecting the upper discharge device 1 and the lower discharge capacitor 4 to the pulse power supply 11 means: connecting the upper discharge device 1 and the lower discharge capacitor 4 to the two poles of the pulse power supply 11 with wires, and in order to facilitate the taking of the lower discharge capacitor 4, the wires can be connected in the form of alligator clips; In step S700, setting the discharge parameters on the control computer 12 and starting the drive motor 10 means: setting the pulse power supply 11 discharge peak current to 0.1-63.8A on the equipment control computer 12, setting the discharge gap to 5-50μm, setting the pulse width to 5-100μs, setting the pulse interval to 5-100μs, setting the knife lift height to 0-10mm, the upper electrode or the lower electrode can be used as the anode and cathode, and setting the discharge time according to the production demand. The above discharge parameters are output to the pulse power supply 11 and the drive motor 10, and the starter motor power supply is turned on. The drive motor 10 is rigidly connected to the upper discharge device 1, and the upper discharge device 1 is driven to perform a translational reciprocating motion in the horizontal direction, and the reciprocating motion range is 0~±10cm; In step S800, starting the discharge power supply and lowering the upper discharge device 1 to a specified height means: starting the discharge on the control computer 12, at which time the longitudinal drive motor 10 drives the upper discharge device 1 to move downward according to the program, so that the lower end of the upper graphite electrode 3 is immersed in the electrolyte 9, and the longitudinal vertical movement stops after reaching the preset discharge gap; In step S900, the upper and lower electrodes break through the electrolyte 9 to start pulse discharge, which means that after step S800, the equipment detects that the gap between the cathode and anode reaches the set parameters and starts pulse discharge, and the pulse discharge voltage is set from 10 to 200V according to the peak current, solution conductivity, gap and other parameters; during discharge, the pulse power supply 11 performs square wave pulse discharge, the pulse width is the discharge duration, and the pulse interval is the discharge interval time; at the same time, the drive motor 10 drives the upper electrode to perform longitudinal lifting and lowering reciprocating motion according to the lifting height setting while moving horizontally, so as to promote product slag discharge; In step S1000, reaching the discharge time to raise the upper discharge device 1 means: reaching the discharge time set by the control computer 12, the pulse power supply 11 stops discharging, and the drive motor 10 drives the upper discharge device 1 to be raised in the vertical direction; In step S1100, judging whether the yield reaches the expectation means observing the suspended product in the electrolyte 9 and the color of the electrolyte 9, roughly judging the yield. If the expected yield is not reached, resetting the discharge parameters and performing cyclic discharge. If the expected yield is reached, proceeding to step S1200; In step S1200, the collection and dispersion of the product includes two steps: product collection and product dispersion. Product collection refers to collecting the electrolyte 9 after the discharge is completed, and collecting graphene in a preset manner, wherein the preset manner includes suction filtration and differential centrifugation. The suction filtration is performed according to a method known in the art, and the differential centrifugation is performed at a speed of 10000-20000 rpm to obtain a centrifugal precipitate. DMF solution is added, and after dispersion and dissolution, the product is centrifuged again at a speed of 1000-5000 rpm to obtain a supernatant. The product is centrifuged again at a speed of 15000-20000 rpm to obtain a centrifugal precipitate. The product dispersion method includes drying the collected sample, freeze-drying it, and directly dissolving it in a DMF solution for retention.

[0041] In order to facilitate those skilled in the art to better understand the technical solution of the present invention, specific embodiments of the present invention are given as follows: Example 1

[0042] See also Figure 4 , a device for preparing graphene in large quantities by pulse discharge, comprising: The upper discharge device 1 is connected to the pulse power supply 11 through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The upper graphite electrode 3 is a graphite rod. When the upper graphite electrode 3 uses a graphite rod, it is directly fixed in the knob of the upper discharge device 1; The lower discharge capacitor 4 is made of conductive metal or graphite, and its length, width and height are all greater than the lower graphite electrode 5, and smaller than the length, width and height of the ultrasonic device 13. The lower discharge capacitor 4 is connected to the pulse power supply 11 through a wire, and is connected to the two poles of the pulse power supply 11 with the upper discharge device 1 respectively; The lower graphite electrode 5 is made of a graphite rod; when the lower graphite electrode 5 is a graphite rod, it is directly placed on the lower discharge container 4; The driving motor 10 is rigidly connected to the upper discharge device 1, and is used to drive the upper discharge device 1 to move in two directions, translation and longitudinal, and is controlled by the control computer 12. The translation is a circular arc reciprocating motion, and the motion range is 0~±10cm, which is used to make the discharge position more uniform; the longitudinal movement is the discharge control process, and the control computer 12 controls the driving motor 10 to move longitudinally to ensure that the upper graphite electrode 3 and the lower graphite electrode 5 are within the working distance; The pulse power supply 11, whose two electrodes are respectively connected to the upper discharge device 1 and the lower discharge capacitor 4, has adjustable positive and negative polarities, and is controlled by a signal from a control computer 12. It is connected to 380V three-phase electricity and can provide square wave pulse discharge; The control computer 12 is used by the user to set parameters on the screen, and the settable parameters include pulse width, pulse interval, current, voltage, gap, knife lifting distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor 10 according to the set values, and outputs discharge control signals to the pulse power supply 11; In this embodiment, the upper graphite electrode 3 and the lower graphite electrode 5 are graphite rods, and the ultrasonic device 13 and the circulation device are not selected.

[0043] In this embodiment, the diameter of the upper graphite rod is 1.5 cm, and the diameter of the lower graphite rod is 3 cm. Control computer 12 discharge parameter settings: Discharge current: 5A, pulse width: 5μs, pulse interval 20μs, knife lift height 5mm, discharge time 20min, discharge gap setting 6μm. Discharge voltage 15V.

[0044] Driving motor 10 translation distance: ±2cm The specific steps are: (1) Fix the cleaned upper graphite electrode 3 graphite rod in the knob of the upper discharge device 1.

[0045] (2) Place the lower graphite electrode 5 in the lower discharge container 4.

[0046] When the circulation device is not selected, the electrolyte 9 is directly added into the lower discharge container 4 to cover the upper surface of the lower graphite electrode 5. In this embodiment, the electrolyte 9 is a conductive electrolyte of 0.5M H2SO4 (4) Turn on the control computer 12, connect the pulse power supply 11 and the power supply of the drive motor 10, and set the electrode polarity, pulse width, pulse interval, current, voltage, gap, knife lifting distance, and discharge time parameters; (5) Turn on the translation mode of the drive motor 10 and adjust it to a suitable translation speed through the controller; (6) Click on the control computer 12 to start discharging, and the control computer 12 sends the control command to the drive motor 10 and the pulse power supply 11. The drive motor 10 drives the upper discharge device 1 to descend to the specified discharge position. Pulse discharge is started between the upper graphite electrode 3 and the lower graphite electrode 5 according to the specified discharge parameters. According to the setting of the knife lifting height, the drive motor 10 drives the upper discharge device 1 to intermittently lift the knife.

[0047] (7) When the set discharge time is reached, the pulse power supply 11 stops discharging, and the upper discharge device 1 rises under the drive of the drive motor 10 and leaves the discharge position, completing the discharge machining process.

[0048] (8) Determine whether the output meets expectations. If it does, collect and disperse the product by vacuum filtration + drying.

[0049] Figure 5 This is a scanning electron microscope photo of the graphene exfoliated by discharge in this embodiment. Example 2

[0050] See also Figure 6 , a device for preparing graphene in large quantities by pulse discharge, comprising: The upper discharge device 1 is connected to the pulse power supply 11 through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The upper graphite electrode 3 is a graphite rod. When the upper graphite electrode 3 uses a graphite rod, it is directly fixed in the knob of the upper discharge device 1; The lower discharge capacitor 4 is made of conductive metal or graphite, and its length, width and height are all greater than the lower graphite electrode 5, and smaller than the length, width and height of the ultrasonic device 13. The lower discharge capacitor 4 is connected to the pulse power supply 11 through a wire, and is connected to the two poles of the pulse power supply 11 with the upper discharge device 1 respectively; The lower graphite electrode 5 is made of a graphite rod; when the lower graphite electrode 5 is a graphite rod, it is directly placed on the lower discharge container 4; The driving motor 10 is rigidly connected to the upper discharge device 1, and is used to drive the upper discharge device 1 to move in two directions, translation and longitudinal, and is controlled by the control computer 12. The translation is a circular arc reciprocating motion, and the motion range is 0~±10cm, which is used to make the discharge position more uniform; the longitudinal movement is the discharge control process, and the control computer 12 controls the driving motor 10 to move longitudinally to ensure that the upper graphite electrode 3 and the lower graphite electrode 5 are within the working distance; The pulse power supply 11, whose two electrodes are respectively connected to the upper discharge device 1 and the lower discharge capacitor 4, has adjustable positive and negative polarities, and is controlled by a signal from a control computer 12. It is connected to 380V three-phase electricity and can provide square wave pulse discharge; The control computer 12 is used by the user to set parameters on the screen, and the settable parameters include pulse width, pulse interval, current, voltage, gap, knife lifting distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor 10 according to the set values, and outputs discharge control signals to the pulse power supply 11; The ultrasonic device 13 includes an ultrasonic coolant 131 and an ultrasonic vibrator 132. The ultrasonic device 13 is an optional accessory. When the accessory is selected, its length, width and height are all greater than the lower discharge container 4. The ultrasonic coolant 131 is located inside the ultrasonic device 13 and is usually tap water. The liquid level of the ultrasonic coolant 131 is lower than the edge of the lower discharge container 4 to prevent the coolant from pouring in. The ultrasonic vibrator 132 is located inside the ultrasonic device 13 and is usually 1 to 6. The control is carried out according to the known method in the field, and the power supply controls the start and end of the ultrasonic assistance. The total ultrasonic power is 60 to 360 W.

[0051] The specific steps are: (1) Fix the cleaned upper graphite electrode 3 graphite rod in the knob of the upper discharge device 1.

[0052] (2) Place the lower graphite electrode 5 in the lower discharge container 4.

[0053] When the circulation device is not selected, the electrolyte 9 is directly added into the lower discharge container 4 to cover the upper surface of the lower graphite electrode 5 .

[0054] (3) When the ultrasonic device 13 is selected, turn on the power of the ultrasonic device 13 and start the ultrasound.

[0055] (4) Turn on the control computer 12, connect the pulse power supply 11 and the power supply of the drive motor 10, and set the electrode polarity, pulse width, pulse interval, current, voltage, gap, knife lifting distance, and discharge time parameters; (5) Turn on the translation mode of the drive motor 10 and adjust it to a suitable translation speed through the controller; (6) Click on the control computer 12 to start discharging, and the control computer 12 sends the control command to the drive motor 10 and the pulse power supply 11. The drive motor 10 drives the upper discharge device 1 to descend to the specified discharge position. Pulse discharge is started between the upper graphite electrode 3 and the lower graphite electrode 5 according to the specified discharge parameters. According to the setting of the knife lifting height, the drive motor 10 drives the upper discharge device 1 to intermittently lift the knife.

[0056] (7) When the set discharge time is reached, the pulse power supply 11 stops discharging, and the upper discharge device 1 rises under the drive of the drive motor 10 and leaves the discharge position, completing the discharge machining process.

[0057] (8) Determine whether the yield meets expectations. If it does, collect and disperse the product by centrifugation at 12,000 rpm, 2,000 rpm, 19,000 rpm, and freeze-drying.

[0058] In this embodiment, the upper graphite electrode 3 and the lower graphite electrode 5 are graphite rods.

[0059] The upper graphite rod (upper graphite electrode 3) has a diameter of 2 cm, and the lower graphite rod (lower graphite electrode 5) has a diameter of 5 cm Control computer 12 discharge parameter settings: Discharge current: 63.8A, pulse width: 100μs, pulse interval 100μs, knife lift height 10 mm, discharge time 3min, discharge gap setting 6μm. Discharge voltage 100V.

[0060] Driving motor 10 translation distance: ±4cm Electrolyte 9: Conductive electrolyte - 0.05M Na2SO4 + 0.02M SDS The number of ultrasonic vibrators 132: 2, and the ultrasonic power is 120W.

[0061] Figure 7 This is a scanning electron microscope photograph of the graphene exfoliated by discharge in this embodiment. Example 3

[0062] See also Figure 8 , a device for preparing graphene in large quantities by pulse discharge, comprising: The upper discharge device 1 is connected to the pulse power supply 11 through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The upper graphite electrode 3 is a graphite rod. When the upper graphite electrode 3 uses a graphite rod, it is directly fixed in the knob of the upper discharge device 1; The lower discharge capacitor 4 is made of conductive metal or graphite, and its length, width and height are all greater than the lower graphite electrode 5, and smaller than the length, width and height of the ultrasonic device 13. The lower discharge capacitor 4 is connected to the pulse power supply 11 through a wire, and is connected to the two poles of the pulse power supply 11 with the upper discharge device 1 respectively; A lower graphite electrode 5, which is a graphite rod and is directly placed on the lower discharge container 4; The driving motor 10 is rigidly connected to the upper discharge device 1, and is used to drive the upper discharge device 1 to move in two directions, translation and longitudinal, and is controlled by the control computer 12. The translation is a circular arc reciprocating motion, and the motion range is 0~±10cm, which is used to make the discharge position more uniform; the longitudinal movement is the discharge control process, and the control computer 12 controls the driving motor 10 to move longitudinally to ensure that the upper graphite electrode 3 and the lower graphite electrode 5 are within the working distance; The pulse power supply 11, whose two electrodes are respectively connected to the upper discharge device 1 and the lower discharge capacitor 4, has adjustable positive and negative polarities, and is controlled by a signal from a control computer 12. It is connected to 380V three-phase electricity and can provide square wave pulse discharge; The control computer 12 is used by the user to set parameters on the screen, and the settable parameters include pulse width, pulse interval, current, voltage, gap, knife lifting distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor 10 according to the set values, and outputs discharge control signals to the pulse power supply 11; The ultrasonic device 13 includes an ultrasonic coolant 131 and an ultrasonic vibrator 132. The ultrasonic device 13 is an optional accessory. When the accessory is selected, its length, width and height are all greater than the lower discharge container 4. The ultrasonic coolant 131 is located inside the ultrasonic device 13 and is usually tap water. The liquid level of the ultrasonic coolant 131 is lower than the edge of the lower discharge container 4 to prevent the coolant from pouring in. The ultrasonic vibrator 132 is located inside the ultrasonic device 13 and is usually 1 to 6. The control is carried out according to the known method in the field, and the power supply controls the start and end of the ultrasonic assistance. The total ultrasonic power is 60 to 360 W.

[0063] The specific steps are: (1) Fix the cleaned upper graphite electrode 3 graphite rod in the knob of the upper discharge device 1.

[0064] (2) Place the lower graphite electrode 5 in the lower discharge container 4.

[0065] When the circulation device is not selected, the electrolyte 9 is directly added into the lower discharge container 4 to cover the upper surface of the lower graphite electrode 5 .

[0066] (3) When the ultrasonic device 13 is selected, turn on the power of the ultrasonic device 13 and start the ultrasound.

[0067] (4) Turn on the control computer 12, connect the pulse power supply 11 and the power supply of the drive motor 10, and set the electrode polarity, pulse width, pulse interval, current, voltage, gap, knife lifting distance, and discharge time parameters; (5) Turn on the translation mode of the drive motor 10 and adjust it to a suitable translation speed through the controller; (6) Click on the control computer 12 to start discharging, and the control computer 12 sends the control command to the drive motor 10 and the pulse power supply 11. The drive motor 10 drives the upper discharge device 1 to descend to the specified discharge position. Pulse discharge is started between the upper graphite electrode 3 and the lower graphite electrode 5 according to the specified discharge parameters. According to the setting of the knife lifting height, the drive motor 10 drives the upper discharge device 1 to intermittently lift the knife.

[0068] (7) When the set discharge time is reached, the pulse power supply 11 stops discharging, and the upper discharge device 1 rises under the drive of the drive motor 10 and leaves the discharge position, completing the discharge machining process.

[0069] (8) Determine whether the yield reaches the expected level. If it reaches the expected level, collect and disperse the product by centrifugation at 20,000 rpm, 3,000 rpm, or 20,000 rpm, and then dissolve the product in DMF solution.

[0070] In this embodiment, the upper graphite electrode 3 and the lower graphite electrode 5 are graphite rods.

[0071] The upper graphite rod has a diameter of 2 cm and the lower graphite rod has a diameter of 5 cm Control computer 12 discharge parameter settings: Discharge current: 1A, pulse width: 10μs, pulse interval 10μs, knife lift height 10mm, discharge time 30min, discharge gap setting 20μm. Discharge voltage 70V.

[0072] Driving motor 10 translation distance: ±5cm Electrolyte 9: Deionized water electrolyte The number of ultrasonic vibrators 132: 3, and the ultrasonic power is 180W.

[0073] Fig. 9 This is a transmission electron microscope photo of the porous graphene exfoliated by discharge in this embodiment. Example 4

[0074] See also Fig.10 , compared with Example 3, the difference between Example 4 and Example 3 is that in this embodiment, the discharge parameters of the control computer 12 are set as follows: discharge current: 5A, pulse width: 10μs, pulse interval 10μs, knife lift height 10mm, discharge time 30min, and discharge gap setting 30μm. Discharge voltage 85V. In this embodiment, the collection and dispersion of the product: 20000 rpm centrifugation, 3000rpm centrifugation, 20000rpm centrifugation, + freeze drying are used to collect and disperse the product. The rest is the same as Example 3 Fig.11 This is a transmission electron microscope photo of the flash-evaporated graphene exfoliated by discharge in this embodiment. Example 5

[0075] See also Fig.12 , a device for preparing graphene in large quantities by pulse discharge, comprising: The upper discharge device 1 is connected to the pulse power supply 11 through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The clamping device 2 is composed of more than two rectangular metal bars 21, and there are through holes in the middle or on both sides of the upper part of the rectangular metal bars 21. The separation and squeezing of the rectangular metal bars 21 are achieved by screws 22. There is an upward metal bar 23 on the upper surface of the middle part of one of the rectangular metal bars 21, which is used to be fixed in the knob of the upper discharge device 1; The upper graphite electrode 3, when the upper graphite electrode 3 uses graphite foil, the graphite foil is neatly arranged in the gap with the rectangular metal strip 21, and the rectangular metal strip 21 is tightened with a screw 22 to fix the upper graphite electrode 3; The lower discharge capacitor 4 is made of conductive metal or graphite, and its length, width and height are all greater than the lower graphite electrode 5, and smaller than the length, width and height of the ultrasonic device 13. The lower discharge capacitor 4 is connected to the pulse power supply 11 through a wire, and is connected to the two poles of the pulse power supply 11 with the upper discharge device 1 respectively; The lower graphite electrode 5, when the lower graphite electrode 5 is a plurality of graphite foils, a clamping device 2 composed of a rectangular metal bar and screws is selected, and the plurality of graphite foils are vertically clamped in the clamping device 2 and placed in the lower discharge container 4, at which time the lower graphite electrode 5 and the upper graphite electrode 3 are arranged crosswise; The driving motor 10 is rigidly connected to the upper discharge device 1, and is used to drive the upper discharge device 1 to move in two directions, translation and longitudinal, and is controlled by the control computer 12. The translation is a circular arc reciprocating motion, and the motion range is 0~±10cm, which is used to make the discharge position more uniform; the longitudinal movement is the discharge control process, and the control computer 12 controls the driving motor 10 to move longitudinally to ensure that the upper graphite electrode 3 and the lower graphite electrode 5 are within the working distance; The pulse power supply 11, whose two electrodes are respectively connected to the upper discharge device 1 and the lower discharge capacitor 4, has adjustable positive and negative polarities, and is controlled by a signal from a control computer 12. It is connected to 380V three-phase electricity and can provide square wave pulse discharge; The control computer 12 is used by the user to set parameters on the screen, and the settable parameters include pulse width, pulse interval, current, voltage, gap, knife lifting distance, discharge time, etc. It outputs control signals to the longitudinal movement of the drive motor 10 according to the set values, and outputs discharge control signals to the pulse power supply 11; The ultrasonic device 13 includes an ultrasonic coolant 131 and an ultrasonic vibrator 132. The ultrasonic device 13 is an optional accessory. When the accessory is selected, its length, width and height are all greater than the lower discharge container 4. The ultrasonic coolant 131 is located inside the ultrasonic device 13 and is usually tap water. The liquid level of the ultrasonic coolant 131 is lower than the edge of the lower discharge container 4 to prevent the coolant from pouring in. The ultrasonic vibrator 132 is located inside the ultrasonic device 13 and is usually 1 to 6. The control is carried out according to the known method in the field, and the power supply controls the start and end of the ultrasonic assistance. The total ultrasonic power is 60 to 360 W.

[0076] In the present embodiment, a circulation device is also included, which is composed of a water pipe 6, a water pump 7 and a circulation container 8. Holes are opened on both sides of the lower discharge container 4, which are sealed and connected with the water pipe 6 to achieve the purpose of circulating the electrolyte 9; wherein the water pipe 6 is composed of 3 sections, and the water pump 7 has a water inlet and a water outlet when it is connected to the power supply; the lower discharge container 4 is connected to the circulation container 8 through the water pipe 6, and the electrolyte 9 in the lower discharge container 4 is led out to the circulation container 8; the lower discharge container 4 is connected to the water pump 7 through the water pipe 6, which is the water outlet of the water pump 7; the water pump 7 is connected to the circulation container 8 through the water pipe 6, which is the water inlet of the water pump 7; thereby, the electrolyte 9 is pumped from the circulation container 8, through the water pipe 6, into the lower discharge container 4 by the water pump 7, submerges the lower graphite electrode 5, and then flows into the circulation container 8 through the water pipe 6 on the other side. The circulation container 8 is located lower than the lower discharge container 4, and liquid discharge is achieved by gravity.

[0077] The specific steps are: (1) Fix the graphite foil of the upper graphite electrode 3 in the gap between the rectangular metal strips of the clamping device 2, tighten the screws, and fix the metal strip in the knob of the upper discharge device 1.

[0078] (2) Place the lower graphite electrode 5 in the lower discharge container 4.

[0079] When the circulation device is selected, the water pump 7 is turned on to pump the electrolyte 9 into the lower discharge container 4 so as to cover the upper surface of the lower graphite electrode 5 , thereby realizing the circulation of the electrolyte 9 .

[0080] (3) When the ultrasonic device 13 is selected, turn on the power of the ultrasonic device 13 and start the ultrasound.

[0081] (4) Turn on the control computer 12, connect the pulse power supply 11 and the power supply of the drive motor 10, and set the electrode polarity, pulse width, pulse interval, current, voltage, gap, knife lifting distance, and discharge time parameters; (5) Turn on the translation mode of the drive motor 10 and adjust it to a suitable translation speed through the controller; (6) Click on the control computer 12 to start discharging, and the control computer 12 sends the control command to the drive motor 10 and the pulse power supply 11. The drive motor 10 drives the upper discharge device 1 to descend to the specified discharge position. Pulse discharge is started between the upper graphite electrode 3 and the lower graphite electrode 5 according to the specified discharge parameters. According to the setting of the knife lifting height, the drive motor 10 drives the upper discharge device 1 to intermittently lift the knife.

[0082] (7) When the set discharge time is reached, the pulse power supply 11 stops discharging, and the upper discharge device 1 rises under the drive of the drive motor 10 and leaves the discharge position, completing the discharge machining process.

[0083] (8) Determine whether the yield meets expectations. If it does, collect and disperse the product by vacuum filtration + freeze drying.

[0084] In this embodiment, the upper graphite electrode 3 and the lower graphite electrode 5 are made of graphite foil.

[0085] The upper graphite electrode 3 has a thickness of 1 mm and is 3 in number. The lower graphite electrode 5 has a thickness of 2 mm. Control computer 12 discharge parameter settings: Discharge current: 0.5A, pulse width: 10μs, pulse interval 10μs, knife lift height 5mm, discharge time 10min, discharge gap setting 20μm. Discharge voltage 160V.

[0086] Driving motor 10 translation distance: ±2cm Electrolyte 9: Deionized water electrolyte Ultrasonic vibrator 132 quantity: 4, ultrasonic power 240W The water pump 7 adopts Zhongke DC40H-24110 water pump 7, and the circulation container 8 selects a plastic bucket.

[0087] Fig.13 This is a scanning electron microscope photograph of graphene exfoliated by discharge in this embodiment. Example 6

[0088] See also Fig.14 Compared with Example 5, the difference between Example 6 and Example 5 is that the upper graphite electrodes 3 are 1 mm thick and there are 4 of them, and the lower graphite electrodes 5 are 1 mm thick and there are 3 of them, which are arranged alternately with the upper graphite electrodes 3.

[0089] Control computer 12 discharge parameter settings: Discharge current: 0.1A, pulse width: 50μs, pulse interval 5μs, knife lift height 8mm, discharge time 60min, discharge gap setting 50μm. Discharge voltage 100V.

[0090] Driving motor 10 translation distance: 0cm The number of ultrasonic vibrators 132: 6, and the ultrasonic power is 360W.

[0091] Fig.15 This is the X-ray diffraction test result of the graphite electrode graphite foil of this embodiment.

[0092] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0093] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A device for preparing graphene in large quantities using pulse discharge, characterized in that: include: The upper discharge device is connected to the pulse power supply through a wire, and has a spiral opening device at the bottom for clamping cylinders of different diameters and tightening them; The clamping device is composed of more than two rectangular metal bars, and there are through holes in the middle or on both sides of the upper part of the rectangular metal bars, and the separation and compression of the rectangular metal bars are achieved by screws. There is an upward metal strip on the upper surface of the middle part of one of the rectangular metal bars, which is used to be fixed in the upper discharge device knob; The upper graphite electrode is one of a graphite rod and a graphite foil. When the upper graphite electrode uses a graphite rod, it is directly fixed in the knob of the upper discharge device. When the upper graphite electrode uses a graphite foil, the graphite foil is neatly arranged in the gap between the graphite foil and the rectangular metal strip, and the rectangular metal strip is tightened with a screw to fix the upper graphite electrode. The lower discharge capacitor has a length, width and height that are greater than the lower graphite electrode and less than the length, width and height of the ultrasonic device. The lower discharge capacitor is connected to the pulse power supply through a wire and is connected to the two poles of the pulse power supply with the upper discharge device respectively. The lower graphite electrode is one of a graphite rod, a single graphite foil and a plurality of graphite foils; when the lower graphite electrode is a graphite rod, it is directly placed on the lower discharge container, and its upper surface area is larger than the lower surface area of ​​the lower graphite electrode, so as to ensure discharge between the two electrodes; when the lower graphite electrode is a plurality of graphite foils, a clamping device composed of a rectangular metal bar and screws is selected, and the plurality of graphite foils are vertically clamped in the clamping device and placed in the lower discharge container, and the lower graphite electrode and the upper graphite electrode are arranged crosswise; The driving motor is rigidly connected to the upper discharge device and is used to drive the upper discharge device to move in both translational and longitudinal directions. It is controlled by a control computer. Translational movement is circular arc reciprocating motion with a motion range of 0~±10cm, which is used to make the discharge position more uniform. Longitudinal movement is the discharge control process. The control computer controls the driving motor to move longitudinally to ensure that the upper graphite electrode and the lower graphite electrode are within the working distance. A pulse power supply, two electrodes of which are connected to the upper discharge device and the lower discharge container respectively; Control computer, which is set by the user on the screen; The ultrasonic device comprises an ultrasonic coolant and an ultrasonic vibrator, the length, width and height of which are all greater than the lower discharge container, the ultrasonic coolant is located inside the ultrasonic device, the liquid level of the ultrasonic coolant is lower than the edge of the lower discharge container; the ultrasonic vibrator is located inside the ultrasonic device.

2. The device for preparing graphene in large quantities by pulse discharge according to claim 1, characterized in that: It also includes a circulation device, which is composed of a water pipe, a water pump and a circulation container. Holes are opened on both sides of the lower discharge capacitor, which are sealed and connected with the water pipe. The lower discharge capacitor and the circulation container are connected by a water pipe to guide the electrolyte in the lower discharge capacitor to the circulation container; the lower discharge capacitor and the water pump are connected by a water pipe, which is the water outlet of the water pump; The water pump is connected to the circulation container through a water pipe, which is the water inlet of the water pump.

3. A method for preparing graphene in large quantities using pulse discharge, characterized in that: The method is implemented based on the device for preparing graphene in large quantities by pulse discharge according to claim 2, and the method comprises the following steps: S100, ultrasonic cleaning of graphite electrodes; S200, fixing the upper graphite electrode to the upper discharge device; S300, placing the lower graphite electrode in the lower discharge container; S400, adding electrolyte into the discharge container so as to cover the electrodes; S600, connecting the upper discharge device and the lower discharge capacitor to a pulse power supply; S700, set the discharge parameters on the control computer and start the drive motor; S800, start the discharge power supply, and the upper discharge device descends to a specified height; S900, the upper and lower electrodes break through the electrolyte and start pulse discharge; S1000, when the discharge time is reached, the upper discharge device is raised; S1100, determine whether the output meets expectations; S1200, collection and dispersion of products.

4. The method for preparing graphene in large quantities by pulse discharge according to claim 3, characterized in that: Also included between step S400 and step S600 is step S500: starting the ultrasonic device and the circulation device.

5. The method for preparing graphene in large quantities by pulse discharge according to claim 4, characterized in that: In step S400, the electrolyte is one of deionized water and a conductive electrolyte, wherein the conductive electrolyte is one of a 0.001M-0.5M sodium sulfate inorganic salt electrolyte, a 0.001M-0.5M SDS surfactant electrolyte, and a 0.01M-1M sulfuric acid acid electrolyte.

6. The method for preparing graphene in large quantities by pulse discharge according to claim 4, characterized in that: In step S700, the discharge parameters are set on the control computer, and starting the drive motor means: setting the pulse power supply discharge peak current to 0.1-63.8A, the discharge gap to 5-50μm, the pulse width to 5-100μs, the pulse interval to 5-100μs, the knife lifting height to 0-10mm, turning on the starter motor power supply, the drive motor is rigidly connected to the upper discharge device, and the upper discharge device is driven to perform translational reciprocating motion in the horizontal direction, and the reciprocating motion range is 0~±10cm; In step S800, starting the discharge power supply and lowering the upper discharge device to a specified height means: starting the discharge on the control computer, at which time the longitudinal drive motor drives the upper discharge device to move downward according to the program, so that the lower end of the upper graphite electrode is immersed in the electrolyte, and after reaching the preset discharge gap, the longitudinal vertical movement stops; In step S1000, raising the upper discharge device when the discharge time is reached means that when the discharge time set by the control computer is reached, the pulse power supply stops discharging, and the driving motor drives the upper discharge device to be raised in the vertical direction.

7. The method for preparing graphene in large quantities by pulse discharge according to claim 4, characterized in that: In step S1200, the collection and dispersion of the product includes two steps: product collection and product dispersion; product collection refers to collecting the electrolyte after the discharge is completed, and collecting graphene in a preset manner, wherein the preset manner includes suction filtration and differential centrifugation, wherein the differential centrifugation is performed at a speed of 10000-20000 rpm to obtain a centrifugal precipitate; DMF solution is added, and after dispersion and dissolution, the product is centrifuged again at a speed of 1000-5000 rpm to obtain a supernatant; the product is centrifuged again at a speed of 15000-20000 rpm to obtain a centrifugal precipitate; the product dispersion method includes drying the collected sample, freeze-drying it, and directly dissolving it in a DMF solution for retention.

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