Graphene-based composite conductive paste and preparation method thereof
By preparing highly conductive graphene through physical methods and combining it with other materials to form an efficient conductive network, the problem of insufficient conductivity of traditional conductive agents and the conductive performance of graphene oxide preparation is solved, and the production of high-performance conductive slurry is realized.
Patent Information
- Application Number
- CN202510704626.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-09-12
AI Technical Summary
Existing traditional conductive agents have weak conductivity, cannot store energy, and have low density, making it difficult to meet the needs of high-performance conductive pastes. In addition, the conductive paste prepared with graphene oxide has deficiencies in conductive performance.
Highly conductive graphene is prepared by physical methods, and fullerene intercalation is used to improve the uniform distribution between layers. It is combined with conductive fillers such as carbon nanotubes, Ketjen black or graphene microsheets, and a ternary compound dispersant and water-based epoxy resin binder are used to form an efficient conductive network.
The electrical conductivity is improved, the production cost is reduced, the compatibility and bending resistance of the material are enhanced, and the process is environmentally friendly and safe.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of polymer modified materials, and in particular to a graphene-based composite conductive paste and a preparation method thereof. Background Art
[0002] With the rapid development of the electronic information industry, human demand for electronic pastes (conductive coatings, conductive adhesives) is increasing and the requirements are getting higher and higher.
[0003] Currently used traditional conductive carbon materials, such as conductive graphite and carbon black, are composed of highly stacked carbon layers, with only the outermost layer in contact with the active material and conducting electricity. With the increasing demand for higher-quality conductive agents, the shortcomings of traditional conductive agents, such as weak conductivity, inability to store energy, and low density, are becoming increasingly apparent. These shortcomings make it difficult to meet the demand for high-performance conductive pastes. Therefore, the development of more efficient conductive agents is a future trend.
[0004] Graphene conductive paste is a new functional paste based on graphene nanomaterials. It has high conductivity, high specific surface area and excellent mechanical properties. In recent years, it has received widespread attention in the fields of energy storage, electronic devices, conductive coatings, etc.; although graphene conductive paste has many good properties, it is limited by factors such as preparation process and dispersion, which makes its conductive performance relatively poor; currently most graphene conductive pastes use graphene oxide in the preparation process. The introduced metal atoms or oxygen-containing functional groups destroy the original properties of graphene to a certain extent, and its structural defects have a certain impact on the improvement of the conductive performance of the conductive paste. Therefore, most conductive pastes prepared by graphene oxide are often doped with more conductive fillers to ensure the stability of their conductive performance. Summary of the Invention
[0005] Based on this, the purpose of the present invention is to provide a graphene-based composite conductive paste with excellent conductivity and stability and a preparation method thereof.
[0006] To achieve the above object, the technical solution of the present invention is as follows: A graphene-based composite conductive paste, characterized in that the conductive paste is composed of the following components in parts by weight: 2-10 parts of highly conductive graphene prepared by a physical method, 1-5 parts of a dispersant, 1-5 parts of a conductive filler, 0.2-1 parts of a binder, 0.5-2 parts of a stabilizer, and 70-80 parts of a solvent; wherein the preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: introducing worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introducing protective gas through a pulse gas port, and adding intercalation medium fullerene into the high-temperature and high-pressure reactor at the same time, mixing natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:0.1-1.2, reacting for 30min-60min, and continuously raising the temperature to 1200°C to obtain composite intercalated graphite; S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
[0007] Furthermore, using fullerene as an intercalation medium can effectively improve the uniform distribution between graphene layers, form a localized charge transfer pathway, and enhance the current-carrying electron mobility of the slurry.
[0008] As a preferred technical solution, the protective gas in step 1 is nitrogen, the nitrogen pressure is ≤0.3MPa, and the internal oxygen concentration is ≤8ppm.
[0009] As a preferred technical solution, in step 2, the temperature of the microwave reaction stage is controlled at 80-100°C, the reaction time is 10 min-30 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 8000-10000 rpm, the gap between the rotor and the stator is 0.2-0.4 mm, the stirring reaction time is 30 min-60 min, the ultrasonic frequency is 20-40 kHz, the power density is 0.5-2 W / mL, the ultrasonic reaction time is 1 h-2 h, and the solvent is pure water.
[0010] Furthermore, the use of highly conductive graphene can effectively reduce the complexity of slurry formulations, reduce dependence on expensive conductive agents, and significantly reduce production costs.
[0011] As a preferred technical solution, the highly conductive graphene powder has 2-5 layers, a particle size (D50) distributed between 4um and 6um, and a basic conductivity greater than 40,000 S / m.
[0012] As a preferred technical solution, the conductive filler is one or more combinations of carbon nanotubes, Ketjen black or graphene microsheets, and its particle size is 80 nm-10 μm.
[0013] As a preferred technical solution, the dispersant is prepared by a ternary compound with solid contents of 1% BYK-420, 1.5% NMP and 1.5% ethanol, and the absorbance of the ternary compound is 1.224 and the potential value is -35.15 mV.
[0014] Furthermore, the use of a ternary compound dispersant can effectively improve the dispersibility of multi-component, multi-particle size particle slurry, while optimizing the interfacial compatibility between the particles and the matrix, thereby improving the electrical performance.
[0015] As a preferred technical solution, the adhesive is prepared by compounding and dispersing graphene slurry, water-based epoxy resin and nano silver wire in a mass ratio of 1-4:1-6:0.5-1.
[0016] Furthermore, graphene and silver nanowires can form a surface-line mutual conductivity network, which can effectively improve the overall conductivity of the slurry. After compounding and curing, the water-based epoxy resin can form a dense cross-linked network, which can effectively enhance its adhesion and cohesion.
[0017] As a preferred technical solution, the stabilizer is nanocellulose or montmorillonite.
[0018] As a preferred technical solution, the solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol with a volume ratio of 1:0.5-1, and the alcohol-based solvent is ethanol or isopropanol.
[0019] A method for preparing a graphene-based composite conductive paste, characterized in that it comprises the following steps: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 3:1-10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry.
[0020] The beneficial effects of the present invention are: 1. The graphene prepared by the physical method with a complete structure has a stable layer structure and is easier to form an efficient conductive network, which reduces the interface resistance and improves the conductive performance of the slurry; 2. Because the surface of the graphene prepared by the physical method is not modified by chemical groups, it is easy to compound with materials such as polymers and metal nanoparticles, and has stronger compatibility; 3. The addition of highly conductive graphene can effectively reduce the use of conductive fillers, thereby reducing the interface contact resistance, improving the overall conductive efficiency and reducing production costs. DETAILED DESCRIPTION
[0021] In order to provide a deeper understanding and appreciation of the technical means and effects achieved by the present invention, a detailed description is given with reference to preferred embodiments, as follows: Example
[0022] A graphene-based composite conductive paste, comprising the following components by weight: 10 parts of highly conductive graphene prepared by a physical method, 5 parts of a dispersant, 1 part of a conductive filler, 1 part of a binder, 2 parts of a stabilizer, and 70 parts of a solvent; wherein the preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: Introduce worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introduce protective gas through the pulse gas port. At the same time, add the intercalation medium fullerene into the high-temperature and high-pressure reactor. Mix natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:1.2, react for 30min-60min, and continuously raise the temperature to 1200°C to obtain composite intercalated graphite; S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
[0023] In this embodiment, the protective gas in step 1 is nitrogen, the nitrogen pressure is ≤0.3 MPa, and the internal oxygen concentration is ≤8 ppm.
[0024] In this embodiment, the temperature of the microwave reaction stage in step 2 is controlled at 80-100° C., the reaction time is 30 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 10,000 rpm, the gap between the rotor and the stator is 0.4 mm, the stirring reaction time is 60 min, the ultrasonic frequency is 40 kHz, the power density is 2 W / mL, the ultrasonic reaction time is 2 h, and the solvent is pure water.
[0025] In this embodiment, the number of layers of the highly conductive graphene powder is 2-5, the particle size (D50) is distributed between 4 μm and 6 μm, and the basic conductivity is greater than 40,000 S / m.
[0026] In this embodiment, the conductive filler is one or more combinations of carbon nanotubes, Ketjen black, or graphene microplatelets, and its particle size is 80 nm-10 μm.
[0027] In this embodiment, the dispersant is prepared by a ternary compound with solid contents of 1% BYK-420, 1.5% NMP, and 1.5% ethanol. The absorbance of the ternary compound is 1.224, and the potential value is -35.15 mV.
[0028] In this embodiment, the adhesive is prepared by mixing and dispersing graphene slurry, water-based epoxy resin and nano silver wires in a mass ratio of 1:6:1.
[0029] In this embodiment, the stabilizer is nanocellulose or montmorillonite.
[0030] In this embodiment, the solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol in a volume ratio of 1:1, and the alcohol-based solvent is ethanol or isopropanol.
[0031] A method for preparing a graphene-based composite conductive paste comprises the following steps: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry. Example
[0032] A graphene-based composite conductive paste, comprising the following components by weight: 8 parts of highly conductive graphene prepared by a physical method, 4 parts of a dispersant, 2 parts of a conductive filler, 0.8 parts of a binder, 1.6 parts of a stabilizer, and 70 parts of a solvent; wherein the preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: Introduce worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introduce protective gas through a pulse gas port. At the same time, add the intercalation medium fullerene into the high-temperature and high-pressure reactor. Mix natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:0.8, react for 40 minutes, and continuously raise the temperature to 1200°C to obtain composite intercalated graphite. S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
[0033] In this embodiment, the protective gas in step 1 is nitrogen, the nitrogen pressure is ≤0.3 MPa, and the internal oxygen concentration is ≤8 ppm.
[0034] In this embodiment, the temperature of the microwave reaction stage in step 2 is controlled at 80-100° C., the reaction time is 20 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 10,000 rpm, the gap between the rotor and the stator is 0.4 mm, the stirring reaction time is 500 min, the ultrasonic frequency is 30 kHz, the power density is 1.5 W / mL, the ultrasonic reaction time is 1.5 h, and the solvent is pure water.
[0035] In this embodiment, the number of layers of the highly conductive graphene powder is 2-5, the particle size (D50) is distributed between 4 μm and 6 μm, and the basic conductivity is greater than 40,000 S / m.
[0036] In this embodiment, the conductive filler is one or more combinations of carbon nanotubes, Ketjen black, or graphene microplatelets, and its particle size is 80 nm-10 μm.
[0037] In this embodiment, the dispersant is prepared by a ternary compound with solid contents of 1% BYK-420, 1.5% NMP, and 1.5% ethanol. The absorbance of the ternary compound is 1.224, and the potential value is -35.15 mV.
[0038] In this embodiment, the adhesive is prepared by mixing and dispersing graphene slurry, water-based epoxy resin and nano silver wires in a mass ratio of 2:4:0.8.
[0039] In this embodiment, the stabilizer is nanocellulose or montmorillonite.
[0040] In this embodiment, the solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol in a volume ratio of 1:0.8, and the alcohol-based solvent is ethanol or isopropanol.
[0041] A method for preparing a graphene-based composite conductive paste, characterized in that it comprises the following steps: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 3:1-10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry. Example
[0042] A graphene-based composite conductive paste, comprising the following components by weight: 4 parts of highly conductive graphene prepared by a physical method, 3 parts of a dispersant, 4 parts of a conductive filler, 0.4 parts of a binder, 1 part of a stabilizer, and 80 parts of a solvent; wherein the preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: Introduce worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introduce protective gas through a pulse gas port. At the same time, add the intercalation medium fullerene into the high-temperature and high-pressure reactor. Mix natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:0.5, react for 30 minutes, and continuously raise the temperature to 1200°C to obtain composite intercalated graphite. S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
[0043] In this embodiment, the protective gas in step 1 is nitrogen, the nitrogen pressure is ≤0.3 MPa, and the internal oxygen concentration is ≤8 ppm.
[0044] In this embodiment, the temperature of the microwave reaction stage in step 2 is controlled at 80-100° C., the reaction time is 10 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 8000 rpm, the gap between the rotor and the stator is 0.2 mm, the stirring reaction time is 40 min, the ultrasonic frequency is 20 kHz, the power density is 1 W / mL, the ultrasonic reaction time is 1 h, and the solvent is pure water.
[0045] In this embodiment, the number of layers of the highly conductive graphene powder is 2-5, the particle size (D50) is distributed between 4 μm and 6 μm, and the basic conductivity is greater than 40,000 S / m.
[0046] In this embodiment, the conductive filler is one or more combinations of carbon nanotubes, Ketjen black, or graphene microplatelets, and its particle size is 80 nm-10 μm.
[0047] In this embodiment, the dispersant is prepared by a ternary compound with solid contents of 1% BYK-420, 1.5% NMP, and 1.5% ethanol. The absorbance of the ternary compound is 1.224, and the potential value is -35.15 mV.
[0048] In this embodiment, the adhesive is prepared by mixing and dispersing graphene slurry, water-based epoxy resin and nano silver wires in a mass ratio of 3:2:0.6.
[0049] In this embodiment, the stabilizer is nanocellulose or montmorillonite.
[0050] In this embodiment, the solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol in a volume ratio of 1:0.6, and the alcohol-based solvent is ethanol or isopropanol.
[0051] A method for preparing a graphene-based composite conductive paste, characterized in that it comprises the following steps: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 3:1-10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry. Example
[0052] A graphene-based composite conductive paste, comprising the following components by weight: 2 parts of highly conductive graphene prepared by a physical method, 1 part of a dispersant, 5 parts of a conductive filler, 0.2 parts of a binder, 0.5 parts of a stabilizer, and 80 parts of a solvent; wherein the preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: Introduce worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introduce protective gas through a pulse gas port. At the same time, add the intercalation medium fullerene into the high-temperature and high-pressure reactor. Mix natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:0.1, react for 30 minutes, and continuously raise the temperature to 1200°C to obtain composite intercalated graphite. S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
[0053] In this embodiment, the protective gas in step 1 is nitrogen, the nitrogen pressure is ≤0.3 MPa, and the internal oxygen concentration is ≤8 ppm.
[0054] In this embodiment, the temperature of the microwave reaction stage in step 2 is controlled at 80-100° C., the reaction time is 10 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 8000 rpm, the gap between the rotor and the stator is 0.2 mm, the stirring reaction time is 30 min, the ultrasonic frequency is 20-40 kHz, the power density is 0.5 W / mL, the ultrasonic reaction time is 1 h, and the solvent is pure water.
[0055] In this embodiment, the number of layers of the highly conductive graphene powder is 2-5, the particle size (D50) is distributed between 4 μm and 6 μm, and the basic conductivity is greater than 40,000 S / m.
[0056] In this embodiment, the conductive filler is one or more combinations of carbon nanotubes, Ketjen black, or graphene microplatelets, and its particle size is 80 nm-10 μm.
[0057] In this embodiment, the dispersant is prepared by a ternary compound with solid contents of 1% BYK-420, 1.5% NMP, and 1.5% ethanol. The absorbance of the ternary compound is 1.224, and the potential value is -35.15 mV.
[0058] In this embodiment, the adhesive is prepared by compounding and dispersing graphene slurry, water-based epoxy resin, and nano silver wires in a mass ratio of 4:1:0.5.
[0059] In this embodiment, the stabilizer is nanocellulose or montmorillonite.
[0060] In this embodiment, the solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol in a volume ratio of 1:0.5, and the alcohol-based solvent is ethanol or isopropanol.
[0061] A method for preparing a graphene-based composite conductive paste, characterized in that it comprises the following steps: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 3:1-10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry.
[0062] Through a number of examples, the following are illustrated: 1. The addition of highly conductive graphene can effectively reduce the use of conductive fillers, thereby reducing interfacial contact resistance, improving overall conductive efficiency, and lowering production costs. At the same time, the reduced amount of conductive agent can effectively solve the problem of electrode brittleness and improve the bending resistance of subsequent application products (such as flexible devices). 2. Graphene prepared using a structurally complete physical method has a stable sheet structure and is more likely to form an efficient conductive network. While reducing interfacial resistance, the conductive properties of the slurry are superior, and the production process is more environmentally friendly and safe. 3. Because the surface of graphene prepared by physical methods is not modified by chemical groups, it is easy to compound with materials such as polymers and metal nanoparticles, has stronger compatibility, and the dispersion system is more stable and less prone to agglomeration.
[0063] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.
Claims
1. A graphene-based composite conductive paste, characterized in that: The conductive paste is composed of the following components by weight: 2-10 parts of highly conductive graphene prepared by a physical method, 1-5 parts of a dispersant, 1-5 parts of a conductive filler, 0.2-1 parts of a binder, 0.5-2 parts of a stabilizer, and 70-80 parts of a solvent. The preparation method of the highly conductive graphene prepared by the physical method is as follows: S1: introducing worm-like expanded graphite into a high-temperature and high-pressure reactor. When the reaction temperature reaches 500°C, introducing protective gas through a pulse gas port, and adding intercalation medium fullerene into the high-temperature and high-pressure reactor at the same time, mixing natural graphite or flake graphite with the intercalation agent in a mass ratio of 1:0.1-1.2, reacting for 30min-60min, and continuously raising the temperature to 1200°C to obtain composite intercalated graphite; S2: The composite intercalated graphite is sequentially introduced into a microwave reactor and an ultrasonic reactor. This process causes the graphite material to be further crushed and exfoliated under the synergistic forces of high shear stress, mutual shearing between particles, and steam explosion effect, thereby obtaining a multi-layer graphene material. S3: The multi-sheet graphene material is homogenized and emulsified in an aqueous environment to further refine it, and then dried to obtain highly conductive graphene.
2. The graphene-based composite conductive paste according to claim 1, characterized in that: In step 1, the protective gas is nitrogen, the nitrogen pressure is ≤0.3 MPa, and the internal oxygen concentration is ≤8 ppm.
3. The graphene-based composite conductive paste according to claim 1, wherein: In step 2, the temperature of the microwave reaction stage is controlled at 80-100° C., the reaction time is 10 min-30 min, the gas pressure is 10 MPa, the rotor speed in the ultrasonic and stirring stages is 8000-10000 rpm, the gap between the rotor and the stator is 0.2-0.4 mm, the stirring reaction time is 30 min-60 min, the ultrasonic frequency is 20-40 kHz, the power density is 0.5-2 W / mL, the ultrasonic reaction time is 1 h-2 h, and the solvent is pure water.
4. The graphene-based composite conductive paste according to claim 1, characterized in that: The highly conductive graphene powder has 2 to 5 layers, a particle size (D50) ranging from 4 μm to 6 μm, and a basic conductivity greater than 40,000 S / m.
5. The graphene-based composite conductive paste according to claim 1, characterized in that: The conductive filler is one or more combinations of carbon nanotubes, Ketjen black or graphene microsheets, and its particle size is 80 nm-10 μm.
6. The graphene-based composite conductive paste according to claim 1, characterized in that: The dispersant is prepared by compounding 1% BYK-420, 1.5% NMP and 1.5% ethanol in solid contents. The absorbance of the ternary compound is 1.224 and the potential value is -35.15 mV.
7. The graphene-based composite conductive paste according to claim 1, characterized in that: The adhesive is prepared by compounding and dispersing graphene slurry, water-based epoxy resin and nano silver wire in a mass ratio of 1-4:1-6:0.5-1.
8. The graphene-based composite conductive paste according to claim 1, characterized in that: The stabilizer is nanocellulose or montmorillonite.
9. The graphene-based composite conductive paste according to claim 1, characterized in that: The solvent is a water-based system or an alcohol-based system, wherein the water-based solvent is a mixture of deionized water and ethylene glycol with a volume ratio of 1:0.5-1, and the alcohol-based solvent is ethanol or isopropanol.
10. The method for preparing a graphene-based composite conductive paste according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Highly conductive graphene and conductive filler are mixed in a mass ratio of 3:1-10:1, a dispersant and a solvent are added, and a high-pressure homogenization treatment (pressure 50-150 MPa, 3-10 cycles) is performed to form a uniformly dispersed composite slurry; S2: Add a binder and a stabilizer to the composite slurry in S1, adjust the solid content to 15%-40%, shear and stir for 1-3 hours at a speed of 2000-6000 rpm until the viscosity reaches 800-3000 mPa·s, to obtain the graphene-based composite conductive slurry.