A processing method for graphite material exfoliation and carbon nanotube material debundling

Abstract

The present application relates to a kind of processing methods for graphite material stripping and carbon nanotube material debundling.The graphite material or carbon nanotube material is mixed with dispersion medium to form slurry, supercritical fluid medium is introduced into slurry to form supercritical complex fluid with cosolvent;Subsequently, slurry passes through the rotor-stator micro-gap formed by high-speed rotor and ultrasonic vibration stator, the vibration surface of ultrasonic vibration stator constitutes the stator shear surface of the rotor-stator micro-gap, so that slurry is subjected to high-speed mechanical shearing and ultrasonic vibration simultaneously in the rotor-stator micro-gap, to make supercritical complex fluid infiltrate into graphite interlayer or carbon nanotube bundle gap;The graphite material after processing enters the first pressure relief branch and is rapidly released to strip, while the carbon nanotube material enters the second pressure relief branch and is released in steps to debundle.The present application realizes the spatial overlap of acoustic field and shear field, and achieves the effect of graphite efficient few-layer stripping and carbon nanotube low-damage debundling.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, and in particular to a method for exfoliating graphite materials and unbundling carbon nanotube materials. Background Technology

[0002] Graphene, due to its excellent electrical and thermal conductivity, high specific surface area, and mechanical properties, has significant application prospects in fields such as battery conductive agents, thermally conductive composite materials, functional coatings, and flexible electronics. Carbon nanotubes, especially single-walled and few-walled carbon nanotubes, are important one-dimensional nanomaterials for constructing highly efficient conductive networks due to their high aspect ratio and excellent electrical conductivity.

[0003] However, graphite sheets exhibit strong van der Waals forces. While conventional liquid-phase ultrasonic exfoliation methods can achieve a certain degree of exfoliation, the ultrasonic cavitation energy is difficult to control precisely, easily leading to sheet breakage and increased lattice defects, thus reducing the intrinsic properties of graphene. Carbon nanotubes, due to the strong van der Waals forces and high aspect ratio causing entanglement, readily form dense bundles and aggregates. Although conventional ultrasonic or strong homogenization treatments can promote dispersion to some extent, excessively high treatment intensities can cause a large number of carbon nanotubes to be severed, significantly reducing their aspect ratio and thus impairing their ability to build conductive networks.

[0004] Supercritical carbon dioxide possesses properties such as low viscosity, high diffusivity, near-zero surface tension, and easy recovery, making it an ideal permeation medium to penetrate the interlayers of graphite or the gaps between carbon nanotube bundles, providing an inside-out basis for subsequent exfoliation or disassembly. Therefore, existing technologies have attempted to combine supercritical fluids with ultrasonic treatment or mechanical shearing for the exfoliation of layered materials or the dispersion of nanotubes. However, existing equipment typically employs conventional stirring, ordinary ultrasound, high-pressure homogenization, or supercritical fluid treatment alone. Ordinary ultrasound and mechanical shearing are often discrete components, with the ultrasonic amplitude transformer and shear stator structurally independent, making it difficult for the acoustic and shear fields to achieve stable spatial overlap. When the material passes through the treatment area, it is actually subjected to ultrasonic and shearing effects at different times and locations, failing to achieve a simultaneous acoustic-shear synergistic enhancement effect on the same micro-region of the material. This severely limits the penetration depth and exfoliation efficiency of supercritical fluids between graphite layers or carbon nanotube bundles. Summary of the Invention

[0005] This invention provides a method for exfoliating graphite materials and unbundling carbon nanotube materials, which can solve the problem in the prior art that the acoustic field and shear field are difficult to form a stable overlap in space.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a processing method for exfoliating graphite materials and unbundling carbon nanotube materials, comprising mixing the material to be processed with a dispersion medium to form a slurry, introducing a supercritical fluid medium and a co-solvent into the slurry to form a supercritical composite fluid, subjecting the slurry to shearing treatment, followed by depressurization treatment and collection of the product.

[0007] The shearing process is carried out within the rotor-stator microgap formed between the high-speed rotor and the ultrasonically vibrating stator. At least one vibrating surface of the ultrasonically vibrating stator constitutes the stator shearing surface of the rotor-stator microgap, thereby simultaneously applying mechanical shearing and ultrasonic vibration to the slurry passing through the rotor-stator microgap, so that the supercritical composite fluid penetrates into the interlayer of graphite material or the intertube gap of carbon nanotube material.

[0008] Furthermore, during the pressure relief process, when the material to be treated is graphite, the slurry that has undergone shearing treatment is introduced into the first pressure relief branch for rapid pressure relief to peel off the graphite; when the material to be treated is carbon nanotube, the slurry that has undergone shearing treatment is introduced into the second pressure relief branch for step-wise pressure relief to unbundle the carbon nanotube.

[0009] Preferably, the dispersion medium is selected from at least one of water, alcohol solvents, ketone solvents, ester solvents, amide solvents, or sulfoxide solvents.

[0010] Preferably, the graphite material includes at least one of natural flake graphite, expanded graphite, artificial graphite, or graphite powder; the carbon nanotube material includes at least one of single-walled carbon nanotubes, few-walled carbon nanotubes, multi-walled carbon nanotubes, or carbon nanotube bundles.

[0011] Preferably, the co-solvent is selected from at least one of alcohols, ketones, or esters; and the supercritical fluid medium is carbon dioxide.

[0012] Preferably, before or simultaneously with the formation of the supercritical composite fluid, an interface stabilizer is introduced into the slurry, the interface stabilizer comprising at least one of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium cholate, sodium deoxycholate, pyrene dispersant, lignin sulfonate, or silane coupling agent.

[0013] Preferably, in the shearing process step, the ultrasonic vibrating stator is driven to generate axial vibration, radial vibration, torsional vibration, or combined directional vibration, thereby forming ultrasonic vibration on the shearing surface of the stator.

[0014] Preferably, in the shearing process step, the spacing of the rotor-stator micro-gap is 20-1000 μm.

[0015] Preferably, in the shearing process: when the material to be processed is graphite, the rotational speed of the high-speed rotor is controlled at 5000-30000 rpm, the ultrasonic vibration frequency is 15-60 kHz, and the ultrasonic power density is 10-500 W / L; when the material to be processed is carbon nanotube, the rotational speed of the high-speed rotor is controlled at 1000-12000 rpm, the ultrasonic vibration frequency is 30-120 kHz, the ultrasonic power density is 10-500 W / L, and pulsed ultrasonic vibration is used.

[0016] Preferably, when the material to be processed is graphite, the rapid pressure relief is achieved by allowing the slurry to flow through at least one of a microporous nozzle, a slit nozzle, an impact chamber, or a homogenizing valve.

[0017] Preferably, in the pressure relief process: the rapid pressure relief is reduced from 10-80 MPa to 0.1-10 MPa, and the pressure relief time is 0.001-5 s; the step-by-step pressure relief is carried out sequentially through at least two back pressure valves, throttle valves, or slow-release chambers, and the pressure drop of each stage is controlled to be 1-15 MPa.

[0018] Beneficial effects The vibrating surface of the ultrasonically vibrating stator constitutes the stator shear surface, achieving spatial overlap between the acoustic and shear fields. When material passes through the rotor-stator micro-gap, it is simultaneously subjected to high-speed shearing and ultrasonic vibration at the same time and location, forming a synergistic acoustic-shear enhancement effect. The shear force exerts macroscopic peeling and dispersion on the material, while the micro-jets and acoustic disturbances generated by ultrasonic cavitation penetrate deep into the micro-gap. The synergy between these two factors significantly improves the penetration depth and efficiency of the supercritical composite fluid into the graphite interlayers or carbon nanotube bundles. Due to its high diffusivity and near-zero surface tension, the supercritical composite fluid, under the synergistic effect of acoustic-shear, can more fully penetrate the graphite interlayers or carbon nanotube bundle gaps, providing an inside-out peeling or unbundling driving force for subsequent pressure relief. For different materials, a branched pressure relief strategy is adopted. Graphite has a two-dimensional layered structure, and the layers are bound by van der Waals forces. It requires instantaneous high-energy impact to achieve explosive peeling. Therefore, a rapid pressure relief branch is adopted to make the supercritical composite fluid between the layers expand instantaneously and generate a strong interlayer peeling force. Carbon nanotubes have a one-dimensional tubular structure. The van der Waals force binding strength between carbon nanotubes is weaker than that between graphite layers. However, carbon nanotubes are sensitive to impact loads. Therefore, a stepped pressure relief branch is adopted to decompose the total pressure drop into multiple small pressure drops, so that the supercritical composite fluid expands in an orderly and gentle manner, generating a fluid combing effect, gradually opening the tube bundle, effectively reducing the probability of carbon nanotubes being cut off, and maintaining their high aspect ratio. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the apparatus that can be used to implement the method of the present invention; Figure 2This is a cross-sectional schematic diagram of the shear unit structure of a high-voltage acoustic vibration stator; Figure 3 Schematic diagram of the connection structure of the branch pressure relief switching unit; Figure 4 This is a schematic diagram of the process flow of the present invention; Figure 5 A schematic diagram of natural flake graphite under an electron microscope; Figure 6 This is a schematic diagram of few-layer graphene under an electron microscope. Figure 7 This is a schematic diagram of single-walled carbon nanotubes before unbundling, as seen under an electron microscope. Figure 8 This is a schematic diagram of unbundled single-walled carbon nanotubes under an electron microscope.

[0020] In the diagram: 1. Carbon dioxide supply unit; 2. Fluid supply unit; 3. Slurry supply unit; 4. High-pressure conveying unit; 5. High-pressure acoustic vibration stator shearing unit; 51. High-pressure reaction chamber; 52. High-speed rotor; 53. Ultrasonic vibration stator; 54. Ultrasonic transducer; 55. Rotor-stator micro-gap; 6. Pressure relief switching unit; 61. High-pressure switching valve; 62. First pressure relief branch; 621. Micro-orifice nozzle; 622. Expansion chamber; 63. Second pressure relief branch; 631. First-stage back pressure valve; 632. Slow-release chamber; 7. Gas-liquid separation unit; 8. Staged reflux unit; 9. Carbon dioxide recovery and compression unit. Detailed Implementation

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" 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 technical solution of this invention 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 this invention.

[0022] like Figure 1 As shown, the apparatus for implementing the method of the present invention includes a carbon dioxide supply unit 1, a fluid supply unit 2, a slurry supply unit 3, a high-pressure conveying unit 4, a high-pressure acoustic vibration stator shearing unit 5, a pressure relief switching unit 6, a gas-liquid separation unit 7, a carbon dioxide recovery and compression unit 9, a staged reflux unit 8, and a control unit.

[0023] The outlets of the carbon dioxide supply unit 1, the fluid supply unit 2, and the slurry supply unit 3 are connected to the inlet of the high-pressure reaction chamber 51 via the high-pressure conveying unit 4. The outlet of the high-pressure reaction chamber 51 is connected to the pressure relief switching unit 6, which includes a first pressure relief branch 62 and a second pressure relief branch 63 that can be switched between each other.

[0024] The outlets of the first pressure relief branch 62 and the second pressure relief branch 63 are both connected to the inlet of the gas-liquid separation unit 7. The gas-liquid separation unit 7 is used to collect the graphene dispersion or carbon nanotube dispersion obtained after pressure relief and to separate the obtained graphene dispersion or carbon nanotube dispersion from carbon dioxide gas. The gas outlet of the gas-liquid separation unit 7 is connected to the carbon dioxide recovery and compression unit 9, and the liquid outlet is connected to the staged reflux unit 8.

[0025] Preferably, the gas-liquid separation unit 7 is a cyclone separator. The cyclone separator utilizes the principle of centrifugal force, causing the gas-liquid mixture composed of product, coarse material and carbon dioxide to enter the cylinder of the cyclone separator tangentially and generate high-speed rotating flow. The denser liquid product is thrown against the wall of the separator under the action of centrifugal force, flows down the wall and is discharged from the bottom liquid outlet, while the less dense carbon dioxide gas forms an upward inward swirling flow in the center and is discharged from the top gas outlet, thereby achieving gas-liquid separation.

[0026] The outlet of the carbon dioxide recovery and compression unit 9 is connected to the carbon dioxide supply unit 1, the high-pressure conveying unit 4, or the high-pressure reaction chamber 51 to form a carbon dioxide circulation loop. The staged reflux unit 8 is equipped with a target product outlet and a coarse material reflux pipeline, which can be connected to the slurry supply unit 3, the high-pressure conveying unit 4, or the high-pressure reaction chamber 51.

[0027] To achieve precise monitoring of process parameters within the high-pressure reaction chamber 51, pressure and temperature sensors are installed inside the chamber. The pressure sensor monitors the pressure within the chamber in real time, ensuring the system remains within the pressure range required for supercritical operation. The temperature sensor monitors the temperature within the chamber in real time, ensuring the system remains within preset supercritical temperature conditions. Both the pressure and temperature sensors are electrically connected to the control unit. The control unit receives the collected pressure and temperature data and sends control commands to each actuator based on preset temperature and pressure thresholds, achieving automated closed-loop control of the entire process.

[0028] The core of the method of this invention lies in the following: In a supercritical composite fluid environment, a rotor-stator micro-gap 55 is formed between the high-speed rotor 52 and the ultrasonic vibrating stator 53, and an acoustic-shear overlap zone is formed within the rotor-stator micro-gap 55 to perform synchronous strong shearing and ultrasonic treatment on the slurry; and depending on whether the material to be treated is graphite or carbon nanotube, different pressure relief branches are selected and switched to achieve efficient peeling or low-damage unbundling.

[0029] The following is combined with Figure 2 and Figure 3 The specific structure and cooperative working method of the high-voltage acoustic vibration stator shear unit 5 and the pressure relief switching unit 6 are described in detail.

[0030] like Figure 2 As shown, the high-pressure acoustic vibration stator shear unit 5 includes a high-pressure reaction chamber 51, which can withstand pressures of 0-30 MPa and temperatures of 0-100℃. Inside the high-pressure reaction chamber 51, a high-speed rotor 52 and an ultrasonic vibration stator 53 are coaxially or eccentrically arranged. The high-speed rotor 52 is driven to rotate by an external drive device; the ultrasonic vibration stator 53 is mechanically connected to an ultrasonic transducer 54 and is driven by the ultrasonic transducer 54 to generate ultrasonic vibrations of a specific frequency and mode.

[0031] At least a portion of the outer surface of the ultrasonic vibrating stator 53 directly forms the stator shear surface of the rotor-stator micro-gap 55. That is, the ultrasonic vibrating stator 53 is not only an ultrasonic energy radiating component, but also acts as a mechanical shearing stator. A rotor-stator micro-gap 55 with a spacing of 20-1000 μm is formed between the shear surface of the high-speed rotor 52 and the vibrating surface of the ultrasonic vibrating stator 53. Preferably, for graphite material exfoliation, the spacing of the rotor-stator micro-gap 55 is preferably 50-150 μm; for carbon nanotube material unbundling, the spacing of the rotor-stator micro-gap 55 is preferably 100-300 μm. When the ultrasonic transducer 54 is energized, the stator shear surface of the ultrasonic vibrating stator 53 will generate high-frequency vibrations. These high-frequency vibrations can be axial, radial, or torsional vibrations, or a combination thereof. Further, a radial vibration mode is preferred, causing the stator shear surface to generate high-frequency displacement along the radial direction of the gap, thereby inducing strong ultrasonic cavitation and acoustic flow effects within the rotor-stator micro-gap 55.

[0032] During operation, a slurry containing a supercritical composite fluid is forcibly conveyed through the rotor-stator micro-gap 55. In this process, the slurry simultaneously endures two forces in the same space: first, the high-shear-rate mechanical shear force generated by the high-speed rotor 52, which exerts macroscopic stretching, peeling, and dispersion effects on graphite sheets or carbon nanotube aggregates; second, the vibrating surface of the ultrasonically vibrating stator 53 directly radiates ultrasonic energy into the slurry within the rotor-stator micro-gap 55, inducing instantaneous cavitation and steady-state acoustic flow. The micro-jets and shock waves generated when the cavitation bubbles collapse can penetrate deep into the micro-gap of the slurry, while the micro-scale eddies formed by the acoustic flow continuously renew the fluid interface layer on the slurry surface. This allows the supercritical composite fluid, with its high diffusivity and near-zero surface tension, to efficiently and rapidly penetrate into the interlayers of graphite or the inter-tube gaps of carbon nanotubes under the combined drive of mechanical shear force and micro-jets, creating sufficient preconditions for subsequent pressure relief peeling or unbundling. Compared to traditional discrete devices where slurry is processed sequentially or in separate areas, this invention achieves true synchronous and synergistic enhancement, greatly improving penetration depth and efficiency.

[0033] like Figure 3 As shown, the pressure relief switching unit 6 also includes a high-pressure switching valve 61, the inlet of which is connected to the outlet of the high-pressure reaction chamber 51. The two outlets of the high-pressure switching valve 61 are respectively connected to the inlet of the first pressure relief branch 62 and the inlet of the second pressure relief branch 63.

[0034] The first pressure relief branch 62 is dedicated to the rapid pressure relief and stripping of graphite materials, and includes at least one of the following: a micro-orifice nozzle 621, a slit nozzle, an expansion chamber 622, an impact chamber, a counter-current nozzle, or a homogenizing valve. The fluid flow rate and pressure drop rate during pressure relief can be controlled by selecting the characteristic dimensions of the nozzle (e.g., micro-orifice diameter or slit width of 20-200 μm). The second pressure relief branch 63 is dedicated to the stepped pressure relief and unbundling of carbon nanotube materials, and includes at least two stages of back pressure valves 631, throttling valves, or slow-release chambers 632 arranged in series. Each stage of the back pressure valve 631 is set with a different opening pressure, thereby decomposing a single large pressure drop into multiple small pressure drops in a stepped release.

[0035] The process flow of this invention is as follows: Figure 4As shown, the specific steps are as follows: the graphite material or carbon nanotube material to be treated is mixed with a dispersion medium and an optional interface stabilizer to obtain a slurry; carbon dioxide and a co-solvent are introduced into the slurry, and the temperature and pressure are adjusted to a supercritical state to form a supercritical composite fluid and maintain pressure for impregnation; then, the slurry carrying the supercritical composite fluid is sent into the high-pressure reaction chamber 51, allowing it to pass through the rotor-stator micro-gap 55, where the slurry undergoes shearing and ultrasonic treatment simultaneously; after the treated high-pressure slurry flows out of the high-pressure reaction chamber 51, it enters the pressure relief switching unit 6, and the corresponding pressure relief branch is selected according to the material type to complete the pressure relief; finally, the two pressure relief products are merged into the same gas-liquid separation unit 7 for gas-liquid separation, the separated liquid product is graded to obtain the target product, the coarse material is returned to the coarse material return pipeline for further processing, and the separated carbon dioxide gas is recovered and recycled.

[0036] Example 1: Preparation of few-layer graphene dispersion by exfoliation of natural flake graphite The object processed in this embodiment is as follows: Figure 5 The natural flake graphite material shown.

[0037] 10g of natural flake graphite and 1g of polyvinylpyrrolidone were added to a 1:1 mixture of ethanol and deionized water in 500mL of water and stirred for 30min to obtain a graphite slurry. The graphite slurry was then fed into a high-pressure reaction chamber 51. Simultaneously, high-purity carbon dioxide and ethanol as a co-solvent were introduced, maintaining the system temperature at 45℃ and the pressure at 25MPa. This allowed the carbon dioxide and ethanol to form a supercritical composite fluid, which was then held under pressure for 20min to allow the supercritical composite fluid to fully pre-permeate into the graphite interlayers.

[0038] Subsequently, the high-speed rotor 52 is started and its speed is set to 15,000 rpm; the ultrasonic transducer 54 is activated, driving the ultrasonic vibrating stator 53 to generate continuous ultrasonic vibration at a frequency of 20 kHz and a power density of 600 W / L. The spacing of the rotor-stator micro-gap 55 is controlled at 200 μm. The graphite slurry is continuously transported through the rotor-stator micro-gap 55 in the high-pressure reaction chamber 51, and simultaneously undergoes high shear and strong ultrasonic treatment within the rotor-stator micro-gap 55 for approximately 20 minutes.

[0039] After processing, the high-pressure graphite slurry flows out and enters the pressure relief switching unit 6. The control unit controls the high-pressure switching valve 61 to connect to the first pressure relief branch 62. The high-pressure graphite slurry is forced through a slit nozzle 622 with a slit width of 100μm, and the pressure drops rapidly from about 15MPa to 1MPa in a very short time (pressure relief time less than 0.5s). The supercritical composite fluid inserted between the graphite layers expands violently and instantaneously, generating a powerful interlayer bursting force, causing the graphite sheets to be rapidly peeled off. The pressure-relieved mixture enters the gas-liquid separation unit 7, where the graphene dispersion is collected. At the same time, the released carbon dioxide gas undergoes gas-liquid separation in the gas-liquid separation unit 7, and the separated carbon dioxide gas is sent to the carbon dioxide recovery and compression unit 9 for recycling. The graphene dispersion collected by the gas-liquid separation unit 7 is sent to the staged reflux unit 8, where it is centrifuged at 3000rpm for 15min. The upper stable graphene dispersion is then collected, which yields the desired product. Figure 6 The few-layer graphene dispersion shown. The insufficiently peeled thick flakes from centrifugation are returned to the slurry supply unit 3 for further processing via the coarse material return pipeline.

[0040] Example 2: Low-damage unbundling of single-walled carbon nanotube bundles The object processed in this embodiment is as follows: Figure 7 The single-walled carbon nanotube material shown.

[0041] 1 g of single-walled carbon nanotubes and 0.5 g of sodium cholate were added to 500 mL of a mixed dispersion medium of deionized water and ethanol in a volume ratio of 3:1. The mixture was premixed by low-speed stirring to obtain a carbon nanotube slurry. The carbon nanotube slurry was then fed into a high-pressure reaction chamber 51, where carbon dioxide and ethanol were introduced as co-solvents. The system temperature was adjusted to 38 °C and the pressure to 18 MPa to form a supercritical composite fluid, which was then held under pressure for 20 min.

[0042] Next, the high-speed rotor 52 is started and its speed is set to 3000 rpm; the ultrasonic transducer 54 is started, driving the ultrasonic vibrating stator 53 to generate pulsed ultrasonic vibration with a frequency of 40 kHz and a power density of 150 W / L, with a pulse duty cycle set to 30%. The spacing of the rotor-stator micro-gap 55 is controlled at 300 μm. When the carbon nanotube slurry passes through the rotor-stator micro-gap 55, it is subjected to gentle shearing and pulsed ultrasonic treatment within the rotor-stator micro-gap 55, with a treatment time of approximately 10 minutes.

[0043] The processed high-pressure carbon nanotube slurry enters the pressure relief switching unit 6. The control unit controls the high-pressure switching valve 61 to connect to the second pressure relief branch 63. The high-pressure carbon nanotube slurry sequentially passes through five back pressure valves, with their opening pressures set to 18MPa, 12MPa, 6MPa, 2MPa, and atmospheric pressure, respectively. Gradual release causes the supercritical composite fluid penetrating between the carbon nanotube bundles to expand in an orderly and gentle manner, generating a fluid combing effect and gradually opening the carbon nanotube bundles. The pressure-relieved mixture enters the gas-liquid separation unit 7, where the carbon nanotube dispersion is collected. Simultaneously, the released carbon dioxide gas is sent to the carbon dioxide recovery and compression unit 9 for recycling through the gas outlet of the gas-liquid separation unit 7. The carbon nanotube dispersion collected by the gas-liquid separation unit 7 is sent to the staged reflux unit 8 for low-speed centrifugation (1000rpm, 10min) to remove a small amount of undecompressed agglomerates, resulting in the following product: Figure 8 The image shows a dispersion of single-walled carbon nanotubes, either individually or in small bundles.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for exfoliating graphite materials and unbundling carbon nanotube materials, comprising mixing the materials to be treated with a dispersion medium to form a slurry, introducing a supercritical fluid medium and a co-solvent into the slurry to form a supercritical composite fluid, subjecting the slurry to shear treatment, followed by depressurization treatment and collection of the product, characterized in that: The shearing process is carried out in the rotor-stator microgap formed between the high-speed rotor and the ultrasonically vibrating stator. At least one vibrating surface of the ultrasonically vibrating stator constitutes the stator shearing surface of the rotor-stator microgap, thereby applying mechanical shearing and ultrasonic vibration to the slurry passing through the rotor-stator microgap simultaneously, so that the supercritical composite fluid penetrates into the interlayer of the graphite material or the intertube gap of the carbon nanotube material. Furthermore, during the pressure relief process, when the material to be treated is graphite, the slurry that has undergone shearing treatment is introduced into the first pressure relief branch for rapid pressure relief to peel off the graphite; when the material to be treated is carbon nanotube, the slurry that has undergone shearing treatment is introduced into the second pressure relief branch for step-wise pressure relief to unbundle the carbon nanotube.

2. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that: The dispersion medium is selected from at least one of water, alcohol solvents, ketone solvents, ester solvents, amide solvents, or sulfoxide solvents.

3. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that: The graphite material includes at least one of natural flake graphite, expanded graphite, artificial graphite, or graphite powder; the carbon nanotube material includes at least one of single-walled carbon nanotubes, few-walled carbon nanotubes, multi-walled carbon nanotubes, or carbon nanotube bundles.

4. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that: The co-solvent is selected from at least one of alcohols, ketones, or esters; the supercritical fluid medium is carbon dioxide.

5. The processing method for exfoliating graphite materials and unbundling carbon nanotube materials according to any one of claims 1-4, characterized in that: Before or simultaneously with the formation of the supercritical composite fluid, an interface stabilizer is also introduced into the slurry, the interface stabilizer including at least one of polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium cholate, sodium deoxycholate, pyrene dispersant, lignin sulfonate, or silane coupling agent.

6. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that: In the shearing process, the ultrasonic vibrating stator is driven to generate axial vibration, radial vibration, torsional vibration or combined vibration, thereby forming ultrasonic vibration on the shearing surface of the stator.

7. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that: In the shearing process, the spacing of the rotor-stator micro-gap is 20-1000 μm.

8. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that, In the shearing process: when the material to be processed is graphite, the rotation speed of the high-speed rotor is controlled at 5000-30000 rpm, the ultrasonic vibration frequency is 15-60 kHz, and the ultrasonic power density is 10-500 W / L; when the material to be processed is carbon nanotube, the rotation speed of the high-speed rotor is controlled at 1000-12000 rpm, the ultrasonic vibration frequency is 30-120 kHz, the ultrasonic power density is 10-500 W / L, and pulsed ultrasonic vibration is used.

9. The processing method for exfoliating graphite materials and unbundling carbon nanotube materials according to claim 1, characterized in that: When the material to be processed is graphite, the rapid pressure relief is achieved by allowing the slurry to flow through at least one of a micro-orifice nozzle, a slit nozzle, an impact chamber, or a homogenizing valve.

10. The processing method for graphite material exfoliation and carbon nanotube material unbundling according to claim 1, characterized in that, In the pressure relief process: the rapid pressure relief is reduced from 10-80MPa to 0.1-10MPa, and the pressure relief time is 0.001-5s; the step pressure relief is carried out sequentially through at least two back pressure valves, throttle valves or slow release chambers, and the pressure drop of each stage is controlled to be 1-15MPa.

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