High-performance electronic paste based on graphene composite material and preparation method thereof

Abstract

The invention relates to the field of electronic paste, and provides high-performance electronic paste based on a graphene composite material and a preparation method of the high-performance electronic paste. The slurry comprises a surface modified graphene / silicon carbide nanowire hybrid, a carbon-coated silver nanorod, epoxy resin, a polyamide curing agent, a KH-550 coupling agent, polyvinylpyrrolidone, fumed silica, polyether modified polydimethylsiloxane and a compound solvent. By constructing a multi-scale conductive network and an interface enhancement structure, excellent conductivity and shear strength of the slurry are realized. The preparation method comprises the steps of in-situ synthesis and surface modification of the graphene hybrid filler, deposition preparation of the carbon and silver nanorods, and a multi-stage dispersion compounding process of all the components under specific temperature control and shearing conditions, and finally the electronic paste which is stable in structure and excellent in performance is formed and is suitable for scenes such as high-reliability electronic packaging and conductive bonding.

Description

Technical Field

[0001] The present invention relates to the field of electronic paste, and in particular to a high-performance electronic paste based on a graphene composite material and a preparation method thereof. Background Art

[0002] In the application scenarios of advanced electronic materials such as high-integration electronic packaging, flexible circuit manufacturing, and high-reliability conductive bonding, electronic paste, as a key functional material, undertakes multiple tasks such as conduction, bonding, packaging, and thermal management. Its performance directly affects the electrical stability, mechanical integrity, and service life of the device. With the rapid development of 5G communications, miniaturized sensors, wearable devices, and other fields, electronic pastes not only need to have excellent conductive properties to ensure efficient transmission of electrical signals, but also need to have high shear strength to resist the risk of structural damage caused by thermal cycles, mechanical stress, and environmental changes. Under complex working conditions such as multiple processing, high-density interconnection, and deformation service, traditional paste materials often find it difficult to achieve coordinated optimization of conductivity and mechanical properties. Therefore, the development of electronic pastes with high conductivity and high shear strength is of great significance for improving device stability, extending service life, and promoting the upgrading of high-end electronic packaging technology. Especially in cutting-edge applications such as flexible electronics and automotive electronics that require both conductive reliability and structural durability, the material design capability of high-performance electronic pastes has become a key technical bottleneck restricting product performance breakthroughs and industrial promotion. Therefore, a new electronic paste system based on conductive filler structure regulation and interface enhancement has significant value in promoting the innovative development of material systems in this field.

[0003] Although there have been continuous advancements in electronic paste materials in terms of filler design, matrix system optimization, and processing technology in recent years, there are still significant deficiencies in meeting the coordinated requirements of high shear strength and excellent electrical conductivity. For example, Chinese Patent Publication No. CN113284672A discloses a preparation method of silver nanowire conductive paste. Although attempts have been made to improve the construction of conductive pathways, due to the lack of systematic regulation of the interfacial compatibility and microstructural stability of the fillers, problems such as the fracture of the conductive network and interfacial debonding are likely to occur in the paste under long-term service or complex stress environments, making it difficult to meet the actual requirements of high shear strength. Another example is the graphene conductive paste proposed in CN119763893A. Although multi-scale carbon materials are introduced to improve conductivity, the contradiction between the uniform distribution of conductive pathways between fillers and the stress transfer mechanism has not been effectively solved, resulting in a still low shear strength of the overall system and affecting its application stability in high-reliability electronic devices. These deficiencies mainly stem from the lack of heterogeneous synergy and interfacial enhancement strategies in the filler structure design of traditional paste systems, and the internal coupling relationship between conductive network construction and mechanical property improvement is often ignored during the composite construction process. Therefore, it is urgent to develop a new type of electronic paste system with multi-scale structure regulation, interfacial functionalization, and network cooperative conduction characteristics starting from the design of the intrinsic structure of the material to achieve the unified improvement of electrical conductivity and shear strength. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The object of the present invention is to provide a high-performance electronic paste based on graphene composite materials and its preparation method to solve the problems of insufficient shear strength and electrical conductivity of current electronic pastes.

[0006] (2) Technical solutions

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A high-performance electronic paste based on graphene composite materials, comprising the following raw materials in parts by weight: 10.0 - 25.0 parts of surface-modified graphene composite filler, 3.5 - 7.0 parts of carbon@silver nanorods; 30.0 - 50.0 parts of the polymer of bisphenol A and epichlorohydrin, 5.0 - 8.0 parts of polyamide curing agent, 1.0 - 3.0 parts of KH-550 coupling agent, 2.0 - 6.0 parts of polyvinylpyrrolidone, 1.0 - 2.0 parts of fumed silica, 0.5 - 1.5 parts of polyether-modified polydimethylsiloxane, 20.0 - 40.0 parts of compound solvent;

[0009] The surface-modified graphene composite filler is obtained by the synergistic surface modification of graphene / silicon carbide nanowire hybrids with KH-560 and polydopamine;

[0010] The described graphene / silicon carbide nanowire hybrid is a graphene sheet and silicon carbide nanowires in-situ grown on the surface of the graphene;

[0011] The described carbon@silver nanorod includes a silver nanorod matrix and a carbon nanolayer coated on the outer surface of the silver nanorod matrix by a chemical deposition process; a heterojunction interface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be in the range of 8 - 30 nm by deposition parameters.

[0012] Further, the mass ratio of the graphene sheet to the silicon carbide nanowires is 1:0.5 - 1:2.0;

[0013] Further, the average lateral size of the graphene sheet is 1 - 5 μm, and the average thickness is 1 - 5 nm;

[0014] Further, the average diameter of the silicon carbide nanowires is 150 - 300 nm, and the average length is 1.0 - 3.5 μm;

[0015] Further, the preparation method of the surface - modified graphene composite filler is as follows: by weight, 100 - 150 parts of the graphene / silicon carbide nanowire hybrid are dispersed in a mixed solvent of 500 - 1000 parts of ethanol and 500 - 1000 parts of water, 1.0 - 5.0 parts of KH - 560 silane coupling agent are added, and a hydrolysis reaction is carried out at 25 - 35 °C with a stirring rate of 200 - 500 rpm for 60 - 120 min. Then, 1.0 - 3.0 parts of polydopamine are added, and the pH is adjusted to 8.0 - 8.5 using a sodium hydroxide solution with a concentration of 0.1 - 0.5 mol / L. Under the condition of constant temperature at 25 - 35 °C, the reaction is continued at a stirring rate of 300 - 600 rpm for 480 - 720 min. After the reaction, the solid - liquid two - phase is separated by vacuum filtration, and the filter cake is washed 3 - 5 times with deionized water to remove residual solvents and unreacted substances. Finally, the filter cake is placed in a vacuum drying oven at 50 - 80 °C and dried for 120 - 180 min until constant weight to obtain the surface - modified graphene composite filler.

[0016] Further, the preparation method of the graphene / silicon carbide nanowire hybrid is as follows: by weight, 5.0 - 10.0 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 50 - 150 parts of polycarbosilane, 80 - 200 parts of tetrahydrofuran, and 0.5 - 3.0 parts of ferrocene. Under the condition of constant temperature at 25 - 50 °C, the mixture is stirred at a rate of 100 - 300 rpm for 120 - 360 min to allow the precursor solution to be fully adsorbed into the pores of the porous graphene. Subsequently, the solid and liquid phases are separated by vacuum filtration, and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace under an argon atmosphere, heated to 300 - 500 °C at a heating rate of 2 - 5 °C / min and held for 60 - 180 min to pyrolyze the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continued to be heated to 800 - 1200 °C at a heating rate of 5 - 10 °C / min and held for 30 - 120 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 25 - 30 °C at a cooling rate of 2 - 5 °C / min to obtain the graphene / silicon carbide nanowire hybrid.

[0017] Further, the preparation method of the porous graphene is as follows: by weight, 5.0 - 10.0 parts of graphene oxide are dispersed in 500 - 2000 parts of deionized water to form a graphene dispersion. 1.0 - 10.0 parts of a nitric acid solution with a mass fraction of 20% - 50% are added, and the mixture is ultrasonically treated for 10 - 30 min. Subsequently, it is transferred to a high-pressure reaction kettle and subjected to a hydrothermal reaction at 180 - 220 °C for 120 - 360 min to generate a three-dimensional graphene hydrogel. After being washed 3 - 5 times with deionized water, it is frozen at -50 - -30 °C for 24 - 48 h, and then placed in a freeze dryer and dried at -80 - -50 °C and a vacuum degree of 5 - 50 Pa for 20 - 24 h to obtain a graphene aerogel. The aerogel is placed in a tubular furnace, nitrogen gas is introduced, and it is heated to 800 - 1200 °C at a heating rate of 5 - 10 °C / min and held for 60 - 180 min to activate the carbon skeleton. Subsequently, it is cooled to 25 - 30 °C at a cooling rate of 2 - 5 °C / min, and then washed with deionized water until the pH of the filtrate is 6.0 - 7.0 to remove the residual inorganic salts. Finally, it is dried in a vacuum drying oven at 50 - 80 °C for 120 - 180 min to obtain the porous graphene.

[0018] The present invention adopts the design of synergistic surface modification of graphene / silicon carbide nanowire hybrids by KH-560 and polydopamine, which is mainly used to enhance the electrical conductivity and shear properties of conductive pastes. By in-situ growing silicon carbide nanowires on the surface of porous graphene sheets, a nano-hybrid with a three-dimensional interconnected structure is constructed, significantly improving the structural stability and mechanical support ability of the filler. On this basis, the KH-560 silane coupling agent is used to achieve chemical bridging of the inorganic-organic interface, enhancing the interfacial bonding between the filler and the resin matrix. At the same time, polydopamine is introduced as a surface functionalization layer to further improve the dispersibility and interfacial energy matching of the filler in the paste system. The excellent electrical conductivity of graphene sheets combined with the rigid support of silicon carbide nanowires effectively inhibits the structural damage caused by stress concentration while maintaining the continuity of the electron path, thus enhancing the shear strength while improving the electrical conductivity. In addition, the differences in size and morphology between graphene sheets and silicon carbide nanowires help to establish a multi-scale synergistic conduction channel, enabling efficient electron migration in the microstructure. The surface modification treatment avoids filler agglomeration by strengthening the interfacial compatibility and dispersion stability, improving the processing uniformity and long-term service stability of the paste. This design strategy realizes the organic integration of the conductive network and the mechanical support system through the synergistic effect of structure construction and interface regulation, meeting the dual requirements of high-performance electronic pastes for electrical and mechanical properties in complex service environments.

[0019] Further, the compound solvent is a mixture of N-methylpyrrolidone, ethanol and dipropylene glycol methyl ether in a volume ratio of (2.0 - 4.0):1:1.

[0020] Further, the preparation method of the carbon@silver nanorods is as follows: by weight, 50 - 80 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction chamber, and then heated to 200 - 300 °C at a heating rate of 5 - 15 °C / min for 30 - 60 min for surface activation treatment in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:2 - 1:4; 20 - 45 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:1 - 1:3. Under the conditions of a carrier gas argon / hydrogen volume ratio of 3:1 - 5:1, a total gas flow rate of 50 - 150 mL / min, and a reaction pressure of 0.1 - 0.5 MPa, the cracking temperature is controlled at 500 - 700 °C to enable the carbon atoms generated by the pyrolysis of the carbon source gas to be directionally deposited on the surface of the silver nanorods. The deposition time is 15 - 30 min. After the reaction, the temperature is gradually decreased to room temperature at a rate gradient of 2 - 5 °C / min while maintaining the argon protection atmosphere to obtain the carbon@silver nanorods.

[0021] Further, the preparation method of the silver nanorods is as follows: by weight, 5-15 parts by weight of silver nitrate and 50-200 parts by weight of deionized water are mixed to form a precursor solution, 0.5-3 parts by weight of a structure-directing agent cetyltrimethylammonium bromide and 0.1-2 parts by weight of a stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved at a rate of 300-800 rpm for 10-30 min in a water bath at 40-60 °C; after adjusting the pH value of the solution to 8.0-11.5, 1-5 parts by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at a rate of 500-1500 rpm at an ambient temperature of 20-30 °C for 30-120 min. After the reaction is terminated, the supernatant is removed by centrifugation at a rate of 8000-12000 rpm for 5-15 min, and the retained nanorod precipitate is washed 3-5 times each with absolute ethanol and deionized water to remove unreacted cetyltrimethylammonium bromide, free silver ions and by-products; the washed product is dispersed in a 0.1-0.5 mol / L aqueous solution of polyvinyl alcohol and ultrasonically treated for 5-10 min to enhance the dispersion stability, and then dehydrated at -50 to -30 °C and 0.01-0.1 MPa by a vacuum freeze dryer for 6-12 h to finally obtain silver nanorods.

[0022] Further, the average diameter of the carbon@silver nanorods is 40-100 nm; the average length is 120-450 nm.

[0023] The design / preparation of the carbon@silver nanorods in the present invention is mainly used to enhance the structural stability and interfacial synergy of the conductive performance and shear performance. By constructing a heterostructure with a carbon-coated layer on the surface of the silver nanorods, while ensuring the conductive ability of the metal core, the dispersibility, interfacial adaptability and antioxidant stability of the material are further improved. As a commonly used highly conductive filler in electronic pastes, the controllability of the structure of silver nanorods is reflected in the preparation process. Through the synergistic effect of cetyltrimethylammonium bromide as a structure-directing agent and polyvinyl alcohol as a stabilizer, combined with the mild reduction environment of ascorbic acid, the controllable synthesis of silver nanorods with uniform size and regular morphology is realized, laying a good structural foundation for the subsequent deposition of the carbon layer. During the chemical vapor deposition process, acetylene and methane are used as carbon source gases to pyrolyze directionally under specific pyrolysis conditions to generate active carbon atoms, and these carbon atoms form a dense coating layer on the surface of the silver nanorods, constructing a composite structure with good interfacial bonding force and charge migration ability. The carbon layer not only plays a protective role for the silver nanorods in the microstructure, preventing them from agglomerating or oxidizing and failing during the paste processing and service process, but also introduces additional conductive channels in the electron transport path, improving the overall electron migration efficiency of the system. In addition, the carbon layer has a regulating effect on the rheological behavior and dispersion state of the paste system, which helps to improve the uniform distribution and interfacial adhesion of the paste in the matrix, thereby enhancing the electrical performance while increasing the overall shear strength. Carbon and silver form a synergistic effect in terms of structure construction and performance release, ensuring that the composite filler has excellent conductive stability and mechanical bearing capacity under complex stress and environmental conditions, and meeting the comprehensive performance requirements of high-performance electronic pastes in applications such as advanced packaging and conductive bonding.

[0024] The present invention also discloses a preparation method of a high-performance electronic paste based on a graphene composite material, comprising the following steps:

[0025] S1: Add the surface-modified graphene composite filler into 1 / 2 of the total mass of the compound solvent, and carry out ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 20-40 kHz and a stirring rate of 300-600 rpm, control the dispersion time to be 10-30 min and the system temperature ≤ 40 °C, to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, forming a graphene dispersion liquid;

[0026] S2: Mix the polymer of bisphenol A and epichlorohydrin with 1 / 2 of the total mass of the compound solvent, and continuously stir at a mechanical stirring rate of 400-800 rpm for 20-40 min under a constant temperature condition of 50-70 °C until the resin is completely dissolved and the solution transmittance ≥ 95%, obtaining a homogeneous epoxy resin solution with a viscosity of 200-500 mPa·s;

[0027] S3: Dropwise add the graphene dispersion obtained in S1 into the S2 epoxy resin solution at a feeding rate of 1 - 5 mL / min, then continue to add carbon@silver nanorods, and mix at 25 - 35 °C through a two-way planetary stirring mechanism at a main shaft rotation speed of 300 - 500 rpm and a self-rotation speed of 800 - 1200 rpm for 30 - 60 min, controlling the shear rate of the mixed system to be 100 - 300 s-1, so that the graphene is embedded in the resin continuous phase in an oligolayer form;

[0028] S4: Sequentially add a polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone, and fumed silica into the S3 composite system, and adopt a staged temperature-rising stirring process: first stir at 25 - 35 °C at 400 - 600 rpm for 15 - 30 min to complete physical mixing, and then raise the temperature to 40 - 50 °C and stir at a low speed of 200 - 400 rpm for 10 - 20 min;

[0029] S5: Add polyether-modified polydimethylsiloxane to the S4 system, stir at 300 - 500 rpm for 10 - 20 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.08 - -0.1 MPa for 10 - 20 min, and then cool it to 25 - 30 °C at a rate of 0.5 - 1.0 °C / min and let it stand for 5 - 10 min to finally obtain the finished electronic paste.

[0030] The present invention adopts a design / preparation method combining multi-stage dispersion compounding and interface regulation, mainly used to enhance the electrical conductivity and shear properties of electronic pastes. By precisely controlling the dispersion state, structure construction method, and interface compatibility of each component, an efficient construction of the conductive network and a synergistic improvement of the mechanical properties are achieved in a multi-component system. In the initial stage, the surface-modified graphene composite filler is subjected to synergistic dispersion treatment by ultrasonic and stirring, so that the interlayer structure is fully dissociated, and at the same time, the surface functional groups are stably exposed, providing conditions for constructing a uniformly distributed conductive path in the resin continuous phase. Subsequently, the polymer of bisphenol A and epichlorohydrin is fully dissolved in the compound solvent to form a homogeneous system with appropriate viscosity, which is beneficial to the coating of the filler and interface wetting. In the mixing stage, the graphene dispersion liquid is slowly dropped into the epoxy resin solution, and carbon@silver nanorods are added to participate in the compounding together. The two-way planetary stirring mechanism makes graphene uniformly distributed in the resin matrix in an oligolayer state under the condition of controlling the shear rate. The carbon@silver nanorods improve the continuity and stability of the conductive channels through the synergistic structure of its metal core and carbon layer. The two jointly construct a stable and efficient conductive network. After that, the addition of polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone, and fumed silica not only further improves the crosslinking density and interface bonding force of the system, but also optimizes the rheological properties and dispersion stability of the paste, ensuring its structural integrity and mechanical bearing capacity during service. Finally, by adding polyether-modified polydimethylsiloxane and vacuum degassing and cooling and standing treatment, the surface properties and internal pore control of the paste are further improved, so as to obtain an electronic paste product with a complete conductive network, strong interface adhesion, and excellent mechanical properties. Through the precise control of each stage and the full play of the synergistic effect of materials, this preparation process realizes an effective linkage between the construction of the conductive filler structure and the regulation of the matrix interface, significantly improving the comprehensive performance of the electronic paste in complex application scenarios.

[0031] (3) Beneficial technical effects

[0032] 1. Through the three-dimensional hybrid structure of graphene and silicon carbide nanowires and the synergistic modification of KH-560 and polydopamine, the present invention significantly improves the electrical conductivity and shear properties of electronic pastes, solves the problems of weak interface bonding and filler agglomeration, and is applicable to complex application scenarios such as high-reliability interconnection packaging.

[0033] 2. Through the hetero-structure design of carbon-coated silver nanorods, the present invention significantly improves the electrical conductivity stability and mechanical strength of electronic pastes, is applicable to the fields of high-density interconnection packaging and flexible electronics, and solves the problems of easy oxidation and agglomeration of traditional fillers and weak interface bonding; the synergistic effect of the carbon layer and the silver core not only protects the conductive path but also enhances the dispersibility. Its unique core-shell structure maintains excellent performance under complex working conditions through multi-path electron transport and stress buffering mechanisms.

[0034] 3. Through the synergistic construction of graphene composite fillers and carbon@silver nanorods, the present invention realizes the simultaneous improvement of conductivity and shear strength, is applicable to high-reliability electronic packaging, has excellent dispersibility, interfacial adhesion and structural stability, and breaks through the performance bottleneck of existing slurries. Description of the Drawings

[0035] Figure 1 It is the morphology diagram of the porous graphene prepared in Example 1 of the present invention.

[0036] Figure 2 It is the morphology diagram of the surface-modified graphene composite filler prepared in Example 1 of the present invention.

[0037] Figure 3 It is the morphology diagram and element distribution of the carbon@silver nanorods prepared in Example 1 of the present invention. Detailed Embodiments

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0039] Example 1

[0040] A high-performance electronic paste based on graphene composite materials, comprising the following raw materials in parts by weight: 10.0 parts of surface-modified graphene composite filler, 3.5 parts of carbon@silver nanorods; 30.0 parts of the polymer of bisphenol A and epichlorohydrin, 5.0 parts of polyamide curing agent, 1.0 part of KH-550 coupling agent, 2.0 parts of polyvinylpyrrolidone, 1.0 part of fumed silica, 0.5 part of polyether-modified polydimethylsiloxane, 20.0 parts of compound solvent;

[0041] The surface-modified graphene composite filler is obtained by the synergistic surface modification of graphene / silicon carbide nanowire hybrids with KH-560 and polydopamine; the graphene / silicon carbide nanowire hybrids are graphene sheets and silicon carbide nanowires in-situ grown on the surface of graphene; the carbon@silver nanorods include a silver nanorod matrix and a carbon nanolayer coated on the outer surface of the silver nanorod matrix by a chemical deposition process; a heterointerface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be within the range of 8 nm by deposition parameters.

[0042] In this embodiment, the mass ratio of graphene sheets to silicon carbide nanowires is 1:0.5; the average lateral size of the graphene sheets is 1 μm, and the average thickness is 1 nm; the average diameter of the silicon carbide nanowires is 150 nm, and the average length is 1.0 μm;

[0043] The preparation method of the surface-modified graphene composite filler in this example is as follows: by weight, 100 parts of graphene / silicon carbide nanowire hybrids are dispersed in a mixed solvent of 500 parts of ethanol and 500 parts of water, 1.0 part of KH-560 silane coupling agent is added, and hydrolysis reaction is carried out at 25°C with a stirring rate of 200 rpm for 60 min. Subsequently, 1.0 part of polydopamine is added, and the pH is adjusted to 8.0 with a 0.1 mol / L sodium hydroxide solution. Under the constant temperature condition of 25°C, the reaction is continuously carried out at a stirring rate of 300 rpm for 480 min. After the reaction is completed, the solid-liquid two phases are separated by vacuum filtration, and the filter cake is washed 3 times with deionized water to remove the residual solvent and unreacted substances. Finally, the filter cake is placed in a vacuum drying oven at 50°C and dried for 120 min until constant weight to obtain the surface-modified graphene composite filler.

[0044] The preparation method of the graphene / silicon carbide nanowire hybrids in this example is as follows: by weight, 5.0 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 50 parts of polycarbosilane, 80 parts of tetrahydrofuran and 0.5 part of ferrocene. Under the constant temperature condition of 25°C, the impregnation is carried out at a stirring rate of 100 rpm for 120 min to allow the precursor solution to be fully adsorbed into the pores of the porous graphene. Subsequently, the solid-liquid two phases are separated by vacuum filtration, and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace under an argon atmosphere, heated to 300°C at a heating rate of 2°C / min and held for 60 min to thermally decompose the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continued to be heated to 800°C at a heating rate of 5°C / min and held for 30 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 25°C at a cooling rate of 2°C / min to obtain the graphene / silicon carbide nanowire hybrids.

[0045] The preparation method of the porous graphene in this example is as follows: by weight, 5.0 parts of graphene oxide are dispersed in 500 parts of deionized water to form a graphene dispersion liquid. 1.0 part of a 20% by mass nitric acid solution is added and ultrasonicated for 10 min. Subsequently, it is transferred to a high-pressure reaction kettle and hydrothermally reacted at 180°C for 120 min to generate a three-dimensional graphene hydrogel. After being washed 3 times with deionized water, it is frozen at -50°C for 24 h, and then placed in a freeze dryer and dried at -80°C and a vacuum degree of 5 Pa for 20 h to obtain a graphene aerogel. The aerogel is placed in a tubular furnace, nitrogen atmosphere is introduced, and it is heated to 800°C at a heating rate of 5°C / min and held for 60 min to activate the carbon skeleton. Subsequently, it is cooled to 25°C at a cooling rate of 2°C / min, and then washed with deionized water until the pH of the filtrate is 6.0 to remove the residual inorganic salts. Finally, it is dried in a vacuum drying oven at 50°C for 120 min to obtain the porous graphene.

[0046] The compound solvent in this embodiment is a mixture of N-methylpyrrolidone, ethanol, and dipropylene glycol methyl ether with a volume ratio of 2.0:1:1.

[0047] The preparation method of the carbon@silver nanorods in this embodiment is as follows: By weight, 80 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction chamber, and then heated to 300 °C at a heating rate of 15 °C / min in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:4 for 60 min of surface activation treatment; 45 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:3. Under the conditions of a carrier gas argon / hydrogen volume ratio of 5:1, a total gas flow rate of 150 mL / min, and a reaction pressure of 0.5 MPa, the cracking temperature is controlled at 700 °C to enable the carbon atoms generated by the pyrolysis of the carbon source gas to be directionally deposited on the surface of the silver nanorods. The deposition time is 30 min. After the reaction ends, the temperature is decreased to room temperature at a rate gradient of 5 °C / min while maintaining the argon protection atmosphere to obtain the carbon@silver nanorods.

[0048] The preparation method of the silver nanorods in this embodiment is as follows: By weight, 15 parts by weight of silver nitrate and 200 parts by weight of deionized water are mixed to form a precursor solution, 3 parts by weight of a structure-directing agent cetyltrimethylammonium bromide and 2 parts by weight of a stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved at 60 °C in a water bath at a rate of 800 rpm for 30 min; after adjusting the pH value of the solution to 11.5, 5 parts by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at a rate of 1500 rpm at an ambient temperature of 30 °C for 120 min. After the reaction is terminated, the supernatant is removed by centrifugation at a rate of 12000 rpm for 15 min, and the retained nanorod precipitate is washed 5 times each with absolute ethanol and deionized water to remove unreacted cetyltrimethylammonium bromide, free silver ions, and by-products; the washed product is dispersed in a 0.5 mol / L polyvinyl alcohol aqueous solution and ultrasonically treated for 10 min to enhance the dispersion stability, and then dehydrated at -30 °C and 0.1 MPa for 12 h by a vacuum freeze dryer to finally obtain the silver nanorods.

[0049] The average diameter of the carbon@silver nanorods in this embodiment is 100 nm; the average length is 450 nm;

[0050] The preparation method of a high-performance electronic paste based on a graphene composite material in this embodiment includes the following steps:

[0051] S1: Add the surface-modified graphene composite filler into half of the total mass of the compound solvent, and perform ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 40 kHz and a stirring rate of 600 rpm. Control the dispersion time to be 30 min and the system temperature ≤ 40 °C to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, forming a graphene dispersion;

[0052] S2: Mix the polymer of bisphenol A and epichlorohydrin with half of the total mass of the compound solvent, and continuously stir at a mechanical stirring rate of 800 rpm for 40 min under the condition of constant temperature at 70 °C until the resin is completely dissolved and the solution transmittance ≥ 95%, obtaining a homogeneous epoxy resin solution with a viscosity of 500 mPa·s;

[0053] S3: Dropwise add the graphene dispersion obtained in S1 into the epoxy resin solution in S2 at a feeding rate of 5 mL / min, then continue to add carbon@silver nanorods, and mix at 35 °C through a two-way planetary stirring mechanism at a main shaft rotation speed of 500 rpm and a self-rotation speed of 1200 rpm for 60 min. Control the shear rate of the mixing system to be 300 s-1 to embed graphene in the resin continuous phase in an oligolayer form;

[0054] S4: Sequentially add polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone and fumed silica into the composite system in S3, and adopt a staged temperature-rising stirring process: first stir at 35 °C at 600 rpm for 30 min to complete physical mixing, and then raise the temperature to 50 °C and stir at a low speed of 400 rpm for 20 min;

[0055] S5: Add polyether-modified polydimethylsiloxane to the system in S4, stir at 500 rpm for 20 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.1 MPa for 20 min, and then cool down to 30 °C at a rate of 1.0 °C / min and stand for 10 min to finally obtain the finished electronic paste.

[0056] Combined Figures 1 to 3 It can be seen that the porous graphene prepared in Example 1 of the present invention has a good three-dimensional pore structure, providing sufficient anchoring sites and reaction space for the in-situ growth of silicon carbide nanowires in the follow-up; Figure 2 The surface-modified graphene composite filler shown presents an interpenetrating structure with a high degree of combination of graphene sheets and silicon carbide nanowires; Figure 3 The carbon@silver nanorods in show a regular one-dimensional morphology, with a dense carbon layer coating, and the EDS element distribution map clearly reveals the element distribution of the carbon layer and the silver core. These microstructure characterization results fully verify the design concept of the synergistic integration of each component in the present invention through structure construction and interface regulation.

[0057] Example 2

[0058] A high-performance electronic paste based on a graphene composite material, comprising the following raw materials in parts by weight: 15 parts of a surface-modified graphene composite filler, 4.5 parts of carbon@silver nanorods; 36 parts of a polymer of bisphenol A and epichlorohydrin, 6 parts of a polyamide curing agent, 1.6 parts of KH-550 coupling agent, 3 parts of polyvinylpyrrolidone, 1.3 parts of fumed silica, 0.8 parts of polyether-modified polydimethylsiloxane, 26 parts of a compound solvent;

[0059] The surface-modified graphene composite filler is obtained by synergistic surface modification of a graphene / silicon carbide nanowire hybrid with KH-560 and polydopamine; the graphene / silicon carbide nanowire hybrid is a graphene sheet and silicon carbide nanowires in-situ grown on the surface of the graphene; the carbon@silver nanorods include a silver nanorod matrix, and a carbon nanolayer coated on the outer surface of the silver nanorod matrix by a chemical deposition process; a heterojunction interface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be in the range of 15 nm by deposition parameters.

[0060] In this embodiment, the mass ratio of the graphene sheet to the silicon carbide nanowires is 1:1.0; the average lateral size of the graphene sheet is 2 μm, and the average thickness is 2 nm; the average diameter of the silicon carbide nanowires is 195 nm, and the average length is 1.8 μm;

[0061] The preparation method of the surface-modified graphene composite filler in this embodiment is as follows: in parts by weight, disperse 115 parts of the graphene / silicon carbide nanowire hybrid in a mixed solvent of 650 parts of ethanol and 650 parts of water, add 2.2 parts of KH-560 silane coupling agent and carry out a hydrolysis reaction at 28 °C with a stirring rate of 290 rpm for 78 min, then add 1.6 parts of polydopamine and use a sodium hydroxide solution with a concentration of 0.2 mol / L to adjust the pH to 8.2, and continuously react at a stirring rate of 390 rpm under a constant temperature condition of 28 °C for 552 min. After the reaction, separate the solid-liquid two phases by vacuum filtration and wash the filter cake 4 times with deionized water to remove residual solvents and unreacted substances. Finally, place the filter cake in a vacuum drying oven at 59 °C and dry it for 138 min to constant weight to obtain the surface-modified graphene composite filler.

[0062] The preparation method of the graphene / silicon carbide nanowire hybrid in this embodiment is as follows: by weight, 6.5 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 80 parts of polycarbosilane, 116 parts of tetrahydrofuran and 1.3 parts of ferrocene, and impregnated at a stirring rate of 160 rpm for 192 min under the condition of constant temperature at 33 °C to enable the precursor solution to be fully adsorbed into the pores of the porous graphene. Subsequently, the solid-liquid two-phase is separated by vacuum filtration and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace under an argon atmosphere, heated to 360 °C at a heating rate of 3 °C / min and kept warm for 96 min to pyrolyze the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continuously heated to 920 °C at a heating rate of 7 °C / min and kept warm for 57 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 27 °C at a cooling rate of 3 °C / min to obtain the graphene / silicon carbide nanowire hybrid.

[0063] The preparation method of the porous graphene in this embodiment is as follows: by weight, 6.5 parts of graphene oxide are dispersed in 950 parts of deionized water to form a graphene dispersion liquid. 3.7 parts of a nitric acid solution with a mass fraction of 29% are added and ultrasonicated for 16 min. Subsequently, it is transferred to a high-pressure reaction kettle and hydrothermally reacted at 192 °C for 192 min to generate a three-dimensional graphene hydrogel. After being washed 4 times with deionized water, it is frozen at -44 °C for 31 h, and then placed in a freeze dryer and dried at -71 °C and a vacuum degree of 19 Pa for 21 h to obtain a graphene aerogel. The aerogel is placed in a tubular furnace, nitrogen gas is introduced into the atmosphere, and it is heated to 920 °C at a heating rate of 7 °C / min and kept warm for 96 min to activate the carbon skeleton. Subsequently, it is cooled to 27 °C at a cooling rate of 3 °C / min, and then washed with deionized water until the pH of the filtrate is 6.3 to remove the residual inorganic salts. Finally, it is dried in a vacuum drying oven at 59 °C for 138 min to obtain the porous graphene.

[0064] The compound solvent in this embodiment is a mixture of N-methylpyrrolidone, ethanol and dipropylene glycol methyl ether in a volume ratio of 2.6:1:1.

[0065] The preparation method of the carbon@silver nanorods in this embodiment is as follows: by weight, 68 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction chamber, and then heated to 260 °C at a heating rate of 11 °C / min in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:3 for 48 min for surface activation treatment; 35 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:2. Under the conditions of a carrier gas argon / hydrogen volume ratio of 4.2:1, a total gas flow rate of 110 mL / min, and a reaction pressure of 0.3 MPa, the cracking temperature is controlled at 620 °C so that the carbon atoms generated by the pyrolysis of the carbon source gas are directionally deposited on the surface of the silver nanorods. The deposition time is 24 min. After the reaction, the temperature is decreased to room temperature at a rate gradient of 4 °C / min while maintaining an argon protection atmosphere to obtain carbon@silver nanorods.

[0066] The preparation method of the silver nanorods in this embodiment is as follows: by weight, 11 parts by weight of silver nitrate and 140 parts by weight of deionized water are mixed to form a precursor solution, 2.0 parts by weight of a structure-directing agent cetyltrimethylammonium bromide and 1.2 parts by weight of a stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved in a 52 °C water bath at a rate of 600 rpm for 22 min; after adjusting the pH value of the solution to 10.1, 3 parts by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at a rate of 1100 rpm at an ambient temperature of 26 °C for 84 min. After the reaction is terminated, the supernatant is removed by centrifugation at a rate of 10400 rpm for 11 min, and the retained nanorod precipitate is washed 4 times with anhydrous ethanol and deionized water respectively to remove unreacted cetyltrimethylammonium bromide, free silver ions and by-products; the washed product is dispersed in a 0.3 mol / L polyvinyl alcohol aqueous solution and ultrasonically treated for 8 min to enhance the dispersion stability, and then dehydrated at -38 °C and 0.06 MPa by a vacuum freeze dryer for 10 h to finally obtain silver nanorods.

[0067] The average diameter of the carbon@silver nanorods in this embodiment is 76 nm; the average length is 318 nm;

[0068] The preparation method of a high-performance electronic paste based on a graphene composite material in this embodiment includes the following steps:

[0069] S1: Add the surface-modified graphene composite filler to 1 / 2 of the total mass of the compound solvent, and perform ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 32 kHz and a stirring rate of 480 rpm. Control the dispersion time to be 22 min and the system temperature ≤ 40 °C to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, and form a graphene dispersion liquid;

[0070] S2: Mix the polymer of bisphenol A and epichlorohydrin with 1 / 2 of the total mass of the compound solvent, and under the condition of constant temperature at 62 °C, stir mechanically at a rate of 640 rpm for 32 min until the resin is completely dissolved and the light transmittance of the solution ≥ 95%, obtaining a homogeneous epoxy resin solution with a viscosity of 380 mPa·s;

[0071] S3: Dropwise add the graphene dispersion obtained in S1 into the epoxy resin solution of S2 at a feeding rate of 3 mL / min, then continue to add carbon@silver nanorods, and mix at 31 °C through a two-way planetary stirring mechanism at a main shaft rotation speed of 420 rpm and a self-rotation speed of 1040 rpm for 48 min, controlling the shear rate of the mixing system to be 220 s-1, so that the graphene is embedded in the resin continuous phase in an oligolayer form;

[0072] S4: Sequentially add polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone and fumed silica into the S3 composite system, and adopt a staged temperature-raising stirring process: first stir at 31 °C at 520 rpm for 24 min to complete physical mixing, and then raise the temperature to 46 °C and stir at a low speed of 320 rpm for 16 min;

[0073] S5: Add polyether-modified polydimethylsiloxane to the S4 system, stir at 420 rpm for 16 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.09 MPa for 16 min, and then cool it to 28 °C at a rate of 0.8 °C / min and let it stand for 8 min to finally obtain the finished electronic paste.

[0074] Example 3

[0075] A high-performance electronic paste based on graphene composite materials, comprising the following raw materials in parts by weight: 19 parts of surface-modified graphene composite filler, 5.6 parts of carbon@silver nanorods; 42 parts of the polymer of bisphenol A and epichlorohydrin, 7 parts of polyamide curing agent, 2.2 parts of KH-550 coupling agent, 4 parts of polyvinylpyrrolidone, 1.6 parts of fumed silica, 1.1 parts of polyether-modified polydimethylsiloxane, 32 parts of compound solvent;

[0076] The surface-modified graphene composite filler is obtained by the synergistic surface modification of graphene / silicon carbide nanowire hybrids with KH-560 and polydopamine; the graphene / silicon carbide nanowire hybrids are graphene sheets and silicon carbide nanowires in-situ grown on the surface of graphene; the carbon@silver nanorods include a silver nanorod matrix and a carbon nanolayer coated on the outer surface of the silver nanorod matrix through a chemical deposition process; a heterojunction interface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be in the range of 21 nm through deposition parameters.

[0077] In this embodiment, the mass ratio of the graphene sheets to the silicon carbide nanowires is 1:1.4; the average lateral size of the graphene sheets is 3 μm, and the average thickness is 3 nm; the average diameter of the silicon carbide nanowires is 240 nm, and the average length is 2.5 μm;

[0078] The preparation method of the surface-modified graphene composite filler in this embodiment is as follows: by weight, 130 parts of the graphene / silicon carbide nanowire hybrid are dispersed in a mixed solvent of 800 parts of ethanol and 800 parts of water, 3.4 parts of KH-560 silane coupling agent are added, and a hydrolysis reaction is carried out at 31 °C with a stirring rate of 380 rpm for 96 min. Subsequently, 2.2 parts of polydopamine are added, and the pH is adjusted to 8.3 with a sodium hydroxide solution with a concentration of 0.3 mol / L. Under the condition of constant temperature at 31 °C, the reaction is continued at a stirring rate of 480 rpm for 624 min. After the reaction is completed, the solid-liquid two phases are separated by vacuum filtration, and the filter cake is washed 4 times with deionized water to remove the residual solvent and unreacted substances. Finally, the filter cake is placed in a vacuum drying oven at 68 °C and dried for 156 min until constant weight to obtain the surface-modified graphene composite filler.

[0079] The preparation method of the graphene / silicon carbide nanowire hybrid in this embodiment is as follows: by weight, 8.0 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 110 parts of polycarbosilane, 152 parts of tetrahydrofuran and 2.0 parts of ferrocene. Under the condition of constant temperature at 40 °C, the impregnation is carried out at a stirring rate of 220 rpm for 264 min to allow the precursor solution to be fully adsorbed into the pores of the porous graphene. Subsequently, the solid-liquid two phases are separated by vacuum filtration, and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace in an argon atmosphere and heated to 420 °C at a heating rate of 4 °C / min and held for 132 min to pyrolyze the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continued to be heated to 1040 °C at a heating rate of 8 °C / min and held for 84 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 28 °C at a cooling rate of 4 °C / min to obtain the graphene / silicon carbide nanowire hybrid.

[0080] The preparation method of the porous graphene in this example is as follows: By weight, 8.0 parts of graphene oxide are dispersed in 1400 parts of deionized water to form a graphene dispersion liquid. 6.4 parts of a nitric acid solution with a mass fraction of 38% are added and ultrasonicated for 22 min. Subsequently, it is transferred to a high-pressure reaction kettle and hydrothermally reacted at 204 °C for 264 min to generate a three-dimensional graphene hydrogel. After washing 4 times with deionized water, it is frozen at -38 °C for 38 h, and then placed in a freeze dryer and dried at -62 °C and a vacuum degree of 32 Pa for 22 h to obtain a graphene aerogel. The aerogel is placed in a tube furnace, nitrogen atmosphere is introduced, and it is heated to 1040 °C at a heating rate of 8 °C / min and held for 132 min to achieve carbon skeleton activation. Subsequently, it is cooled to 28 °C at a cooling rate of 4 °C / min, and then washed with deionized water until the pH of the filtrate is 6.6 to remove residual inorganic salts. Finally, it is dried in a vacuum drying oven at 68 °C for 156 min to obtain porous graphene.

[0081] The compound solvent in this example is a mixture of N-methylpyrrolidone, ethanol, and dipropylene glycol methyl ether in a volume ratio of 3.2:1:1.

[0082] The preparation method of the carbon@silver nanorods in this example is as follows: By weight, 59 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction cavity. Subsequently, it is heated to 230 °C at a heating rate of 8 °C / min in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:3 for surface activation treatment for 39 min. 28 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:2. Under the conditions of a carrier gas argon / hydrogen volume ratio of 3.6:1, a total gas flow rate of 80 mL / min, and a reaction pressure of 0.2 MPa, the cracking temperature is controlled at 560 °C to enable the carbon atoms generated by the pyrolysis of the carbon source gas to be directionally deposited on the surface of the silver nanorods. The deposition time is 20 min. After the reaction, it is cooled to room temperature at a rate gradient of 3 °C / min while maintaining the argon protection atmosphere to obtain carbon@silver nanorods.

[0083] The preparation method of silver nanorods in this embodiment is as follows: by weight, 8 parts by weight of silver nitrate is mixed with 95 parts by weight of deionized water to form a precursor solution, 1.3 parts by weight of the structure-directing agent cetyltrimethylammonium bromide and 0.7 parts by weight of the stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved in a water bath at 46 °C at a rate of 450 rpm for 16 min; after adjusting the pH value of the solution to 9.1, 2 parts by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at a rate of 800 rpm at an ambient temperature of 23 °C for 57 min. After the reaction is terminated, the supernatant is removed by centrifugation at a rate of 9200 rpm for 8 min, and the remaining nanorod precipitate is washed 4 times with absolute ethanol and deionized water respectively to remove unreacted cetyltrimethylammonium bromide, free silver ions and by-products; the washed product is dispersed in a 0.2 mol / L polyvinyl alcohol aqueous solution and ultrasonically treated for 7 min to enhance the dispersion stability, and then dehydrated at -44 °C and 0.04 MPa for 8 h by a vacuum freeze dryer to finally obtain silver nanorods.

[0084] The average diameter of the carbon@silver nanorods in this embodiment is 58 nm; the average length is 219 nm;

[0085] The preparation method of a high-performance electronic paste based on a graphene composite material in this embodiment includes the following steps:

[0086] S1: Add the surface-modified graphene composite filler to 1 / 2 of the total mass of the compound solvent, and perform ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 26 kHz and a stirring rate of 390 rpm. Control the dispersion time to be 16 min and the system temperature ≤ 40 °C to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, and form a graphene dispersion;

[0087] S2: Mix the polymer of bisphenol A and epichlorohydrin with 1 / 2 of the total mass of the compound solvent, and continuously stir at a mechanical stirring rate of 520 rpm under a constant temperature condition of 56 °C for 26 min until the resin is completely dissolved and the solution transmittance ≥ 95%, and obtain a homogeneous epoxy resin solution with a viscosity of 290 mPa·s;

[0088] S3: Dropwise add the graphene dispersion obtained in S1 to the epoxy resin solution in S2 at a feeding rate of 2 mL / min, then continue to add carbon@silver nanorods, and mix at 28 °C through a two-way planetary stirring mechanism at a main shaft speed of 360 rpm and a self-rotation speed of 920 rpm for 39 min. Control the shear rate of the mixing system to be 160 s-1 to embed graphene in the resin continuous phase in an oligolayer form;

[0089] S4: Sequentially add polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone, and fumed silica into the S3 composite system. Adopt a staged temperature-rising stirring process: first stir at 28°C at 460 rpm for 20 min to complete physical mixing, then raise the temperature to 43°C and stir at a low speed of 260 rpm for 13 min;

[0090] S5: Add polyether-modified polydimethylsiloxane to the S4 system, stir at 360 rpm for 13 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.09 MPa for 13 min, then cool it to 27°C at a rate of 0.7°C / min and let it stand for 7 min to finally obtain the finished electronic paste.

[0091] Example 4

[0092] A high-performance electronic paste based on graphene composite materials, comprising the following raw materials in parts by weight: 25.0 parts of surface-modified graphene composite filler, 7.0 parts of carbon@silver nanorods; 50.0 parts of the polymer of bisphenol A and epichlorohydrin, 8.0 parts of polyamide curing agent, 3.0 parts of KH-550 coupling agent, 6.0 parts of polyvinylpyrrolidone, 2.0 parts of fumed silica, 1.5 parts of polyether-modified polydimethylsiloxane, 40.0 parts of compound solvent;

[0093] The surface-modified graphene composite filler is obtained by the synergistic surface modification of graphene / silicon carbide nanowire hybrids with KH-560 and polydopamine; the graphene / silicon carbide nanowire hybrids are graphene sheets and silicon carbide nanowires in-situ grown on the surface of graphene; the carbon@silver nanorods include a silver nanorod matrix and a carbon nanolayer coated on the outer surface of the silver nanorod matrix through a chemical deposition process; a heterojunction interface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be within the range of 30 nm through deposition parameters.

[0094] In this example, the mass ratio of graphene sheets to silicon carbide nanowires is 1:2.0; the average lateral size of the graphene sheets is 5 μm, and the average thickness is 5 nm; the average diameter of the silicon carbide nanowires is 300 nm, and the average length is 3.5 μm;

[0095] The preparation method of the surface-modified graphene composite filler in this example is as follows: by weight, 150 parts of graphene / silicon carbide nanowire hybrids are dispersed in a mixed solvent of 1000 parts of ethanol and 1000 parts of water, 5.0 parts of KH-560 silane coupling agent is added, and hydrolysis reaction is carried out at 35 °C with a stirring rate of 500 rpm for 120 min. Subsequently, 3.0 parts of polydopamine is added, and the pH is adjusted to 8.5 with a 0.5 mol / L sodium hydroxide solution. Under the condition of constant temperature at 35 °C, the reaction is continuously carried out at a stirring rate of 600 rpm for 720 min. After the reaction is completed, the solid-liquid two phases are separated by vacuum filtration, and the filter cake is washed 5 times with deionized water to remove residual solvents and unreacted substances. Finally, the filter cake is placed in a vacuum drying oven at 80 °C and dried for 180 min until constant weight to obtain the surface-modified graphene composite filler.

[0096] The preparation method of the graphene / silicon carbide nanowire hybrids in this example is as follows: by weight, 10.0 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 150 parts of polycarbosilane, 200 parts of tetrahydrofuran and 3.0 parts of ferrocene. Under the condition of constant temperature at 50 °C, the impregnation is carried out at a stirring rate of 300 rpm for 360 min to allow the precursor solution to be fully adsorbed into the pores of the porous graphene. Subsequently, the solid-liquid two phases are separated by vacuum filtration, and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace in an argon atmosphere, heated to 500 °C at a heating rate of 5 °C / min and held for 180 min to thermally decompose the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continued to be heated to 1200 °C at a heating rate of 10 °C / min and held for 120 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 30 °C at a cooling rate of 5 °C / min to obtain the graphene / silicon carbide nanowire hybrids.

[0097] The preparation method of the porous graphene in this example is as follows: by weight, 10.0 parts of graphene oxide are dispersed in 2000 parts of deionized water to form a graphene dispersion liquid. 10.0 parts of a 50% mass fraction nitric acid solution is added and ultrasonicated for 30 min. Subsequently, it is transferred to a high-pressure reaction kettle and hydrothermally reacted at 220 °C for 360 min to generate a three-dimensional graphene hydrogel. After being washed 5 times with deionized water, it is frozen at -30 °C for 48 h, and then placed in a freeze dryer and dried at -50 °C and a vacuum degree of 50 Pa for 24 h to obtain a graphene aerogel. The aerogel is placed in a tubular furnace, nitrogen atmosphere is introduced, and it is heated to 1200 °C at a heating rate of 10 °C / min and held for 180 min to activate the carbon skeleton. Subsequently, it is cooled to 30 °C at a cooling rate of 5 °C / min, and then washed with deionized water until the pH of the filtrate is 7.0 to remove residual inorganic salts. Finally, it is dried in a vacuum drying oven at 80 °C for 180 min to obtain the porous graphene.

[0098] The composite solvent in this embodiment is a mixture of N-methylpyrrolidone, ethanol and dipropylene glycol methyl ether with a volume ratio of 4.0:1:1.

[0099] The preparation method of the carbon@silver nanorods in this embodiment is as follows: By weight, 50 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction chamber, and then heated to 200 °C at a heating rate of 5 °C / min in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:2 for 30 min for surface activation treatment; 20 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:1. Under the conditions of a carrier gas argon / hydrogen volume ratio of 3:1, a total gas flow rate of 50 mL / min, and a reaction pressure of 0.1 MPa, the cracking temperature is controlled at 500 °C to enable the carbon atoms generated by the pyrolysis of the carbon source gas to be directionally deposited on the surface of the silver nanorods. The deposition time is 15 min. After the reaction, the temperature is decreased to room temperature at a rate gradient of 2 °C / min while maintaining the argon protection atmosphere to obtain the carbon@silver nanorods.

[0100] The preparation method of the silver nanorods in this embodiment is as follows: By weight, 5 parts by weight of silver nitrate and 50 parts by weight of deionized water are mixed to form a precursor solution, 0.5 part by weight of a structure-directing agent cetyltrimethylammonium bromide and 0.1 part by weight of a stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved at 300 rpm in a 40 °C water bath for 10 min; after adjusting the solution pH value to 8.0, 1 part by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at 500 rpm at 20 °C for 30 min. After the reaction is terminated, the supernatant is removed by centrifugation at 8000 rpm for 5 min, and the remaining nanorod precipitate is washed 3 times each with absolute ethanol and deionized water to remove unreacted cetyltrimethylammonium bromide, free silver ions and by-products; the washed product is dispersed in a 0.1 mol / L polyvinyl alcohol aqueous solution and ultrasonically treated for 5 min to enhance the dispersion stability, and then dehydrated at -50 °C and 0.01 MPa for 6 h by a vacuum freeze dryer, and finally the silver nanorods are obtained.

[0101] The average diameter of the carbon@silver nanorods in this embodiment is 40 nm; the average length is 120 nm;

[0102] The preparation method of a high-performance electronic paste based on a graphene composite material in this embodiment includes the following steps:

[0103] S1: Add the surface-modified graphene composite filler to half of the total mass of the compound solvent, and perform ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 20 kHz and a stirring rate of 300 rpm. Control the dispersion time to be 10 min and the system temperature ≤ 40 °C to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, forming a graphene dispersion;

[0104] S2: Mix the polymer of bisphenol A and epichlorohydrin with half of the total mass of the compound solvent, and continuously stir at a mechanical stirring rate of 400 rpm under a constant temperature condition of 50 °C for 20 min until the resin is completely dissolved and the solution transmittance ≥ 95%, obtaining a homogeneous epoxy resin solution with a viscosity of 200 mPa·s;

[0105] S3: Dropwise add the graphene dispersion obtained in S1 to the epoxy resin solution in S2 at a feeding rate of 1 mL / min, then continue to add carbon@silver nanorods, and mix at 25 °C through a two-way planetary stirring mechanism at a main shaft rotation speed of 300 rpm and a self-rotation speed of 800 rpm for 30 min. Control the shear rate of the mixed system to be 100 s-1 to embed graphene in the resin continuous phase in an oligolayer form;

[0106] S4: Sequentially add polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone, and fumed silica to the composite system in S3, and adopt a staged temperature-rising stirring process: first stir at 25 °C at 400 rpm for 15 min to complete physical mixing, and then raise the temperature to 40 °C and stir at a low speed of 200 rpm for 10 min;

[0107] S5: Add polyether-modified polydimethylsiloxane to the system in S4, stir at 300 rpm for 10 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.08 MPa for 10 min, and then cool it to 25 °C at a rate of 0.5 °C / min and let it stand for 5 min to finally obtain the finished electronic paste.

[0108] Comparative Example 1

[0109] It is basically the same as Example 1, except that KH-560 silane coupling agent is not added in the preparation of the surface-modified graphene composite filler.

[0110] Comparative Example 2

[0111] It is basically the same as Example 1, except that polydopamine is not added in the preparation of the surface-modified graphene composite filler.

[0112] Comparative Example 3

[0113] It is basically the same as Example 1, except that the graphene / silicon carbide nanowire hybrid is not subjected to the synergistic surface modification treatment of KH-560 and polydopamine.

[0114] Comparative Example 4

[0115] It is basically the same as Example 1, except that the addition amount of KH-560 is 0.5 parts.

[0116] Comparative Example 5

[0117] It is basically the same as Example 1, except that: in the preparation of porous graphene, the hydrothermal reaction temperature is adjusted to 150 °C, and the freeze-drying temperature is -20 °C.

[0118] Comparative Example 6

[0119] It is basically the same as Example 1, except that: ferrocene catalyst is not added to the precursor solution of the graphene / silicon carbide nanowire hybrid.

[0120] Comparative Example 7

[0121] It is basically the same as Example 1, except that: in the carbon source gas of the carbon@silver nanorods, the molar ratio of acetylene to methane is 1:5, and the deposition time is 5 min.

[0122] Comparative Example 8

[0123] It is basically the same as Example 1, except that: in the mixed solvent, the volume ratio of N-methylpyrrolidone, ethanol and dipropylene glycol methyl ether is 1:1:1.

[0124] Comparative Example 9

[0125] It is basically the same as Example 1, except that: the pH value of the reduction reaction of the silver nanorods is 6.0, and polyvinyl alcohol is not added as a stabilizer.

[0126] Comparative Example 10

[0127] It is basically the same as Example 1, except that: the drying temperature of the surface-modified graphene composite filler is 120 °C, and the drying time is 60 min.

[0128] Performance Test:

[0129] Conductivity Test (Four-Probe Method): Using a four-probe resistivity tester (Loresta GP MCP-T700), according to the ASTM D4496 standard, the slurry is coated on a PET substrate to form a uniform film layer of 10×50 mm 2 (with a thickness of 50±5 μm). After curing, the sheet resistance is measured. The test conditions are 25±2 °C and a relative humidity of 50±5%, and the average value is taken after repeating three times. The conductivity is calculated through the resistivity formula.

[0130] Shear Strength Test (ASTM D1002 Single-Lap Shear Method): Prepare a single-lap structure according to the ASTM D1002 standard. Use the slurry to bond two aluminum alloy test pieces, and after curing, test the shear strength on a universal material testing machine at a rate of 1.3 mm / min.

[0131] Adhesion Test (ASTM D3359 Tape Peel Test): Coat the cured slurry on an aluminum alloy substrate (size 75×150×1 mm 3 ) that has been cleaned with acetone. After curing for 24 hours at 25 ± 2°C and 50 ± 5% RH, use a single-edge blade to cut the coating surface vertically and crosswise into a 6×6 grid at 1 mm intervals, ensuring that the blade cuts into the substrate. Stick a 3M No. 600 transparent tape (width 25 mm, adhesive force ≥ 3.0 N / cm 2 ) and apply a constant pressure (roll with a 500 g weight 3 times), then peel the tape at a uniform speed at a 60° angle. Observe the coating peeling area through an optical microscope and evaluate the bonding strength according to the ASTM standard classification (0B - 5B), where 0B represents complete peeling and 5B indicates no visible peeling.

[0132] The properties of the electronic slurries of Examples 1 - 4 and Comparative Examples 1 - 10 are summarized in Table 1.

[0133] Table 1 Summary of the Properties of the Electronic Slurries of Examples 1 - 4 and Comparative Examples 1 - 10

[0134]

[0135] As can be seen from Table 1, the absence of KH-560 will weaken the chemical bridging effect between the inorganic filler and the resin matrix, resulting in insufficient interfacial bonding force, thus reducing the shear strength and significantly decreasing the adhesion; the absence of polydopamine will affect the wettability and polarity matching of the filler surface, leading to a decrease in dispersibility, and further causing a decrease in shear strength and adhesion, and the electrical conductivity is slightly disturbed; without surface modification treatment, the synergistic regulation effects of the interface and dispersion of KH-560 and polydopamine will be lost simultaneously, resulting in a comprehensive deterioration of the properties in terms of electrical conductivity, mechanical strength and adhesion; although the insufficient addition amount of KH-560 still has partial interface strengthening effect, the combination is not sufficient, and the adhesion is slightly lower than that of the example; insufficient hydrothermal reaction temperature and freeze-drying conditions will lead to underdeveloped pore structure and decreased specific surface area of the prepared porous graphene, affecting the loading of silicon carbide nanowires and the subsequent path construction, resulting in the interruption of the conduction path and damage to the overall performance; the absence of ferrocene catalyst will inhibit the in-situ growth efficiency of silicon carbide nanowires, but because there is still a conduction path in graphene, the electrical conductivity is less affected and the shear strength decreases slightly; insufficient carbon layer deposition time of carbon@silver nanorods results in incomplete carbon layer coverage. Although the protective effect is weakened, the exposure of silver nuclei increases, the electrical conductivity is slightly better and the shear strength remains medium; the change of the proportion of the compound solvent has limited influence on the polarity matching and dissolution ability of the system, the dispersibility decreases slightly but the overall performance is close to that of the example; the absence of polyvinyl alcohol stabilizer will cause the aggregation of silver nanorods, affecting their uniform distribution and interfacial adhesion, resulting in a significant decrease in both electrical conductivity and adhesion; insufficient drying temperature and time may cause residual moisture or organic solvents in the filler, thus interfering with the curing process and interfacial bonding, manifested as slightly lower adhesion.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that all equivalent structural transformations made under the concept of the present invention by using the content of the specification and drawings of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A high-performance electronic paste based on graphene composite materials, characterized in that, It comprises raw materials in the following parts by weight: 10.0 - 25.0 parts of surface-modified graphene composite filler, 3.5 - 7.0 parts of carbon@silver nanorods; 30.0 - 50.0 parts of the polymer of bisphenol A and epichlorohydrin, 5.0 - 8.0 parts of polyamide curing agent, 1.0 - 3.0 parts of KH-550 coupling agent, 2.0 - 6.0 parts of polyvinylpyrrolidone, 1.0 - 2.0 parts of fumed silica, 0.5 - 1.5 parts of polyether-modified polydimethylsiloxane, 20.0 - 40.0 parts of compound solvent; The surface-modified graphene composite filler is obtained by the synergistic surface modification of graphene / silicon carbide nanowire hybrid with KH-560 and polydopamine; The graphene / silicon carbide nanowire hybrid is graphene sheets and silicon carbide nanowires in-situ grown on the surface of graphene; The carbon@silver nanorods include a silver nanorod matrix and a carbon nanolayer coated on the outer surface of the silver nanorod matrix by a chemical deposition process; a heterojunction interface is formed between the carbon nanolayer and the silver nanorod matrix, and its layer thickness is regulated to be in the range of 8 - 30 nm by deposition parameters.

2. The high-performance electronic paste based on graphene composite material according to claim 1, characterized in that, The mass ratio of the graphene sheets to the silicon carbide nanowires is 1:0.5 - 1:2.0; The average lateral size of the graphene sheets is 1 - 5 μm, and the average thickness is 1 - 5 nm; The average diameter of the silicon carbide nanowires is 150 - 300 nm, and the average length is 1.0 - 3.5 μm.

3. A high-performance electronic paste based on graphene composite material according to claim 1, characterized in that, The preparation method of the surface-modified graphene composite filler is as follows: by weight, disperse 100 - 150 parts of graphene / silicon carbide nanowire hybrid in a mixed solvent of 500 - 1000 parts of ethanol and 500 - 1000 parts of water, add 1.0 - 5.0 parts of KH-560 silane coupling agent and carry out a hydrolysis reaction at 25 - 35°C with a stirring rate of 200 - 500 rpm for 60 - 120 min, then add 1.0 - 3.0 parts of polydopamine and use a sodium hydroxide solution with a concentration of 0.1 - 0.5 mol / L to adjust the pH to 8.0 - 8.5, continuously react at a stirring rate of 300 - 600 rpm under the constant temperature condition of 25 - 35°C for 480 - 720 min, after the reaction is completed, separate the solid-liquid two phases by vacuum filtration and wash the filter cake 3 - 5 times with deionized water to remove residual solvents and unreacted substances, and finally place the filter cake in a vacuum drying oven at 50 - 80°C and dry it for 120 - 180 min to constant weight to obtain the surface-modified graphene composite filler.

4. A high-performance electronic paste based on a graphene composite material as described in claim 1, wherein, The preparation method of the described graphene / silicon carbide nanowire hybrid is as follows: by weight, 5.0 - 10.0 parts of porous graphene are impregnated in a silicon carbide precursor solution composed of 50 - 150 parts of polycarbosilane, 80 - 200 parts of tetrahydrofuran, and 0.5 - 3.0 parts of ferrocene. Under the condition of constant temperature at 25 - 50 °C, with a stirring rate of 100 - 300 rpm, it is impregnated for 120 - 360 min to fully adsorb the precursor solution into the pores of the porous graphene. Subsequently, the solid-liquid two phases are separated by vacuum filtration, and the unadsorbed liquid components are removed to retain the porous graphene loaded with the precursor. The porous graphene loaded with the precursor is transferred to a tubular furnace in an argon atmosphere, heated to 300 - 500 °C at a heating rate of 2 - 5 °C / min and held for 60 - 180 min to pyrolyze the polycarbosilane into silicon carbide nanocrystallites. Subsequently, it is continued to be heated to 800 - 1200 °C at a heating rate of 5 - 10 °C / min and held for 30 - 120 min to promote the in-situ growth of silicon carbide nanowires on the surface of the porous graphene. Finally, it is cooled to 25 - 30 °C at a cooling rate of 2 - 5 °C / min to obtain the graphene / silicon carbide nanowire hybrid.

5. The high-performance electronic paste based on graphene composite material according to claim 4, characterized in that, The preparation method of the described porous graphene is as follows: by weight, 5.0 - 10.0 parts of graphene oxide are dispersed in 500 - 2000 parts of deionized water to form a graphene dispersion. 1.0 - 10.0 parts of a nitric acid solution with a mass fraction of 20% - 50% are added and ultrasonicated for 10 - 30 min. Subsequently, it is transferred to a high-pressure reaction kettle and subjected to a hydrothermal reaction at 180 - 220 °C for 120 - 360 min to generate a three-dimensional graphene hydrogel. After being washed 3 - 5 times with deionized water, it is frozen at -50 - -30 °C for 24 - 48 h, and then placed in a freeze dryer and dried at -80 - -50 °C and a vacuum degree of 5 - 50 Pa for 20 - 24 h to obtain a graphene aerogel. The aerogel is placed in a tubular furnace, nitrogen gas is introduced into the atmosphere, and it is heated to 800 - 1200 °C at a heating rate of 5 - 10 °C / min and held for 60 - 180 min to activate the carbon skeleton. Subsequently, it is cooled to 25 - 30 °C at a cooling rate of 2 - 5 °C / min, and then washed with deionized water until the pH of the filtrate is 6.0 - 7.0 to remove the residual inorganic salts. Finally, it is dried in a vacuum drying oven at 50 - 80 °C for 120 - 180 min to obtain the porous graphene.

6. The high-performance electronic paste based on graphene composite material according to claim 1, characterized in that, The described compound solvent is a mixture of N-methylpyrrolidone, ethanol, and dipropylene glycol methyl ether in a volume ratio of (2.0 - 4.0):1:

1.

7. A high-performance electronic paste based on graphene composite material as claimed in claim 1, characterized in that, The preparation method of the carbon@silver nanorods is as follows: by weight, 50-80 parts by weight of silver nanorods are placed in a chemical vapor deposition reaction chamber, and then heated to 200-300 °C at a heating rate of 5-15 °C / min in a reducing atmosphere with a volume mixing ratio of argon to hydrogen of 1:2-1:4 for 30-60 min for surface activation treatment; 20-45 parts by weight of a mixed carbon source gas of acetylene and methane are simultaneously introduced into the reaction system, where the molar ratio of acetylene to methane is 1:1-1:

3. Under the conditions of a carrier gas argon / hydrogen volume ratio of 3:1-5:1, a total gas flow rate of 50-150 mL / min, and a reaction pressure of 0.1-0.5 MPa, the cracking temperature is controlled to be 500-700 °C so that the carbon atoms generated by the pyrolysis of the carbon source gas are directionally deposited on the surface of the silver nanorods, and the deposition time is 15-30 min. After the reaction, the temperature is decreased to room temperature at a rate gradient of 2-5 °C / min while maintaining the argon protection atmosphere to obtain carbon@silver nanorods.

8. The high-performance electronic paste based on graphene composite material according to claim 7, characterized in that, The preparation method of the silver nanorods is as follows: by weight, 5-15 parts by weight of silver nitrate and 50-200 parts by weight of deionized water are mixed to form a precursor solution, 0.5-3 parts by weight of a structure-directing agent cetyltrimethylammonium bromide and 0.1-2 parts by weight of a stabilizer polyvinyl alcohol are added, and the mixture is stirred and dissolved at 300-800 rpm in a water bath at 40-60 °C for 10-30 min; after adjusting the pH value of the solution to 8.0-11.5, 1-5 parts by weight of ascorbic acid is added as a reducing agent, and the silver ion reduction reaction is continuously stirred at 500-1500 rpm at an ambient temperature of 20-30 °C for 30-120 min. After the reaction is terminated, the supernatant is removed by centrifugation at a rate of 8000-12000 rpm for 5-15 min, and the remaining nanorod precipitate is washed 3-5 times with anhydrous ethanol and deionized water respectively to remove unreacted cetyltrimethylammonium bromide, free silver ions and by-products; the washed product is dispersed in a 0.1-0.5 mol / L polyvinyl alcohol aqueous solution and ultrasonically treated for 5-10 min to enhance the dispersion stability, and then dehydrated at -50 to -30 °C and 0.01-0.1 MPa by a vacuum freeze dryer for 6-12 h to finally obtain silver nanorods.

9. A high-performance electronic paste based on a graphene composite material as described in claim 1, characterized in that, The average diameter of the carbon@silver nanorods is 40-100 nm; the average length is 120-450 nm.

10. The preparation method of a high-performance electronic paste based on a graphene composite material as described in claim 1, characterized in that, It includes the following steps: S1: Add the surface-modified graphene composite filler to 1 / 2 of the total mass of the compound solvent, and perform ultrasonic dispersion under the synergistic action of an ultrasonic frequency of 20-40 kHz and a stirring rate of 300-600 rpm. Control the dispersion time to be 10-30 min and the system temperature ≤ 40 °C to achieve the interlayer dissociation of graphene and the stable dispersion of surface functional groups, and form a graphene dispersion liquid; S2: Mix the polymer of bisphenol A and epichlorohydrin with 1 / 2 of the total mass of the compound solvent, and under the condition of constant temperature at 50 - 70 °C, continuously stir at a mechanical stirring rate of 400 - 800 rpm for 20 - 40 min until the resin is completely dissolved and the light transmittance of the solution is ≥ 95%, to obtain a homogeneous epoxy resin solution with a viscosity of 200 - 500 mPa·s; S3: Dropwise add the graphene dispersion obtained in S1 into the epoxy resin solution in S2 at a feeding rate of 1 - 5 mL / min, then continue to add carbon@silver nanorods, and at 25 - 35 °C, mix for 30 - 60 min through a two-way planetary stirring mechanism at a main shaft rotation speed of 300 - 500 rpm and a self-rotation speed of 800 - 1200 rpm, and control the shear rate of the mixing system to be 100 - 300 s-1, so that the graphene is embedded in the resin continuous phase in an oligolayer form; S4: Sequentially add polyamide curing agent, KH-550 coupling agent, polyvinylpyrrolidone and fumed silica into the S3 composite system, and adopt a stepwise temperature-raising stirring process: first stir at 25 - 35 °C at 400 - 600 rpm for 15 - 30 min to complete physical mixing, and then raise the temperature to 40 - 50 °C and stir at a low speed of 200 - 400 rpm for 10 - 20 min; S5: Add polyether-modified polydimethylsiloxane to the S4 system, stir at 300 - 500 rpm for 10 - 20 min, then transfer it to a vacuum degassing device, degas at a vacuum degree of -0.08 - -0.1 MPa for 10 - 20 min, and then cool it to 25 - 30 °C at a rate of 0.5 - 1.0 °C / min and let it stand for 5 - 10 min to finally obtain the finished electronic paste.

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