A graphene conductive paste

Abstract

The invention belongs to the technical field of conductive pastes, and discloses a graphene conductive paste, comprising the following raw materials in parts by weight: 6-12 parts of graphene powder; 2-4 parts of metal nanoparticles; 80-85 parts of N,N-dimethylformamide; 1-2 parts of dopant; and 3-6 parts of auxiliary agent. The graphene conductive paste of the invention has good conductivity, good stability, and strong practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive pastes, and in particular to a graphene conductive paste. Background Art

[0002] Conductive paste refers to a paste in which a conductive agent is evenly dispersed in a dispersant. It is widely used in electronic components and circuit boards. Its main function is to provide good electrical and thermal conductivity, ensuring smooth transmission of current and effective heat dissipation, thereby ensuring stable operation of the equipment and extending its service life.

[0003] Among the conductive pastes currently on the market, graphene conductive paste has excellent conductivity, fluidity, stability and mechanical properties. Although graphene conductive paste has many good properties, it still has certain shortcomings. For example, due to factors such as the preparation process, the selection of dispersants and the defects of graphene itself, the conductivity of the paste may decrease; due to the differences in the surface properties of graphene and the substrate, it is difficult to form good adhesion, which may lead to a decrease in conductivity or failure. In addition, graphene conductive paste will be affected by environmental factors such as temperature and humidity during long-term use, resulting in performance aging. The conductivity of the aged paste will decrease, thereby affecting the service life and performance stability of the battery. Summary of the invention

[0004] The purpose of the present invention is to provide a graphene conductive slurry with good conductivity, good stability and strong practicality.

[0005] The technical solution adopted to achieve the purpose of the present invention is: a graphene conductive slurry, comprising the following raw materials in parts by weight: 6-12 parts of graphene powder; 2-4 parts of metal nanoparticles; 80-85 parts of N,N-dimethylformamide; 1-2 parts of dopant; and 3-6 parts of auxiliary agent.

[0006] Furthermore, the metal nanoparticles are one or more of gold nanoparticles, silver nanoparticles, copper nanoparticles and aluminum nanoparticles.

[0007] Furthermore, the dopant is a nitrogen-containing compound and / or a boron-containing compound.

[0008] Furthermore, the nitrogen-containing compound is melamine, ammonia water or hydrazine hydrate.

[0009] Furthermore, the boron-containing compound is sodium borohydride or boric acid.

[0010] Furthermore, the auxiliary agents include dispersants, thickeners and surfactants.

[0011] As a conductive filler, graphene can form a continuous conductive network, so that the material has a lower resistivity, thereby effectively conducting current. In the present invention, the graphene conductive filler is a key raw material for conductive performance, which provides a conductive channel to ensure that the conductive slurry has good conductive performance. The graphene conductive filler powder of the present invention is composed of graphene nanosheets, which have a high specific surface area and excellent conductive properties, and can enhance the mechanical properties of the conductive slurry. When adding graphene powder, the present invention mainly uses stirring, ultrasonic vibration and other process treatments to make the graphene nanosheets uniformly dispersed in the solvent, avoid agglomeration and sedimentation, thereby improving the stability and service life of the conductive slurry.

[0012] Adding metal particles to graphene conductive paste can significantly improve the conductive properties of conductive paste, and the coordinated effect of graphene conductive filler and metal filler can further improve the conductive properties of conductive paste. Specifically, the ultra-large specific surface area and high conductivity of graphene can make the metal filler more evenly dispersed between graphene sheets, avoiding the agglomeration and sedimentation of the metal filler. At the same time, the metal particles can also fill the gaps between the graphene sheets to form a tighter conductive network, thereby improving the conductive properties of the conductive paste. The addition of metal particles can also improve the dispersibility of graphene conductive filler in the solvent, so that the graphene conductive filler is more evenly dispersed in the resin, thereby improving the uniformity and stability of the conductive paste. In addition, the addition of metal particles can also improve the heat resistance of the conductive paste, so that it can still maintain good conductive properties under high temperature environment.

[0013] During actual processing, the metal particle filler can be selected according to actual needs. Gold and silver are precious metals with good electrical conductivity and chemical stability. Copper and aluminum are relatively common metals with good electrical conductivity and relatively low cost. The electrical conductivity of copper is second only to silver, while aluminum has a lighter weight and good electrical conductivity, making it suitable for use in situations where weight reduction is required. Taking into account cost, conductivity and weight, the metal particle filler in the present invention adopts a composite filler of silver, copper and aluminum, and the weight ratio of the three is silver: copper: aluminum = 1:2:2.

[0014] Nitrogen atoms and boron atoms in nitrogen-containing compounds or boron-containing compounds can have a significant effect on the electronic structure of graphene after being doped with graphene. Specifically, after nitrogen atoms are doped into graphene, they will form a synergistic effect with carbon atoms in graphene, change its electronic structure, effectively change the electronic structure of graphene, thereby improving its electrical conductivity, and the incorporation of nitrogen atoms increases the carrier concentration of graphene, which allows more electrons to move freely in graphene, thereby improving its electrical conductivity. The p-orbital atomic orbital of the boron atom forms a new energy level on graphene, thereby interacting with the original π energy level of graphene, thereby forming a new conductive path, which helps to improve the electrical conductivity of graphene. The present invention preferably compound boric acid and ammonia water according to a mass fraction of 1:1.

[0015] Simultaneous doping of nitrogen-containing compounds and boron-containing compounds into graphene can further synergistically optimize its electronic structure, improve the chemical reactivity of graphene, and enhance the conductivity of graphene conductive paste by enhancing physical properties.

[0016] Dispersants, thickeners and surfactants are crucial to the performance of graphene conductive pastes. Specifically, common dispersants, thickeners and surfactants in current graphene conductive pastes can be selected. In the present invention, polyvinyl pyrrolidone and sodium dodecylbenzene sulfonate are selected as dispersants; ethyl cellulose is selected as thickeners; and surfactants are Span 85 and 1,4-butyrolactone. The ratio of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, ethyl cellulose, Span 85 and 1,4-butyrolactone is 5:3:2:2:1.

[0017] The beneficial effects of the present invention are:

[0018] 1. The graphene in the present invention can form a continuous conductive network, so that the material has a lower resistivity, thereby effectively conducting current. At the same time, the metal particles can also fill the gaps between the graphene sheets to form a more compact conductive network, thereby improving the conductive properties of the conductive paste;

[0019] 2. Doping nitrogen-containing compounds and boron-containing compounds into graphene can further synergistically optimize its electronic structure, improve the chemical reactivity of graphene, and enhance the conductivity of graphene conductive paste by enhancing physical properties;

[0020] 3. The graphene conductive slurry prepared by using the raw materials of the present invention has good conductivity, good stability and strong practicality. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0022] Example 1

[0023] A graphene conductive paste comprises the following raw materials in parts by weight: 6 parts of graphene powder; 2 parts of metal nanoparticles; 80 parts of N,N-dimethylformamide; 1 part of dopant; and 3 parts of auxiliary agent.

[0024] In this embodiment, the metal nanoparticle filler is a metal nanoparticle composite filler of silver, copper and aluminum, and the weight ratio of the three is silver: copper: aluminum = 1:2:2.

[0025] In this embodiment, the doping agents boric acid and ammonia water are compounded in a mass fraction of 1:1.

[0026] In this embodiment, a dispersant, a thickener and a surfactant are also included, and the dispersant is selected from polyvinyl pyrrolidone and sodium dodecyl benzene sulfonate; the thickener is selected from ethyl cellulose; the surfactant is Span 85 and 1,4-butyrolactone. The weight ratio of polyvinyl pyrrolidone, sodium dodecyl benzene sulfonate, ethyl cellulose, Span 85 and 1,4-butyrolactone is 5:3:2:2:1.

[0027] The preparation method of the graphene conductive slurry of the present invention mainly comprises the following steps:

[0028] Step S1, doping pretreatment, dissolving boric acid in deionized water to form a boric acid solution, and diluting ammonia water for standby use; dispersing graphene powder in 10% N, N-dimethylformamide to form a graphene dispersion;

[0029] Step S2, graphene doping, slowly drop the boric acid solution into the graphene dispersion, stirring while adding to ensure uniform mixing; then slowly drop the diluted ammonia solution into the above mixture, and continue stirring. The order and ratio of adding boric acid and ammonia need to be optimized according to experimental conditions to achieve the best doping effect.

[0030] Step S3, heating. After the doping in step S2 is completed, the mixture is heated to promote the uniform distribution of boric acid on the graphene surface and possible chemical reactions. After the heating treatment, excess solvent and unreacted dopant are removed by centrifugation.

[0031] Step S4, mixing, adding the treated doped graphene powder together with metal nanoparticles, dispersant, thickener and surfactant into the remaining N,N-dimethylformamide, and then wet grinding, filtering and degassing are performed.

[0032] Wet grinding is carried out in a sand mill or a grinding disperser, and large particle impurities and unevenly dispersed graphene agglomerates in the slurry are removed by a filtering device; then vacuum degassing is used to remove bubbles in the slurry to ensure the uniformity and stability of the slurry.

[0033] Embodiment 2-5

[0034] The types of raw materials and the preparation methods of Examples 2-5 are exactly the same as those of Example 1, and the only difference is the amount of the raw materials used. The specific differences in the amount of raw materials used in Examples 2-5 and Example 1 are shown in Table 1 below:

[0035] Table 1 Comparison of raw material dosages in Examples 1-5

[0036]

[0037] The raw materials of Examples 1-5 were processed to prepare graphene conductive pastes, and then the performance of the graphene conductive pastes was tested, including the conductive performance and stability. Commercially available graphene conductive pastes were randomly selected as comparative examples.

[0038] The conductivity test was conducted at room temperature and standard atmospheric pressure, using a four-eye probe to measure the conductivity, and the result was expressed as conductivity (S / cm). The stability test was conducted by centrifuging at 3000 rpm for 30 minutes, and then standing for 24 hours to observe the stratification.

[0039] The test results are shown in Table 2 below:

[0040] Table 2 Comparison of performance test results of graphene conductive pastes of Examples 1-5

[0041] Test Group Conductivity (S / cmm) Stability (stratification) Example 1 2658 Slightly delaminated Example 2 2763 No significant changes Example 3 2856 No significant changes Example 4 2813 No significant changes Example 5 2735 No significant changes Comparative Example 2418 Slightly delaminated

[0042] According to the results in Table 2 above, it can be seen that the performance of the graphene conductive slurry of the present invention is better than that of commercially available products, and in the graphene conductive slurry of the present invention, the conductivity and stability of the products of Examples 2-5 are better than those of Example 1, and Example 3 has the best effect. Among Examples 2-5, Example 3 of the present invention is the best embodiment.

[0043] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the scope of the present invention should be included in the protection scope of the present invention.

Claims

1. A graphene conductive slurry, characterized in that: The invention comprises the following raw materials in parts by weight: 6-12 parts of graphene powder; 2-4 parts of metal nanoparticles; 80-85 parts of N,N-dimethylformamide; 1-2 parts of dopant; and 3-6 parts of auxiliary agent.

2. The graphene conductive paste according to claim 1, characterized in that: The metal nanoparticles are one or more of gold nanoparticles, silver nanoparticles, copper nanoparticles and aluminum nanoparticles.

3. The graphene conductive paste according to claim 1 or 2, characterized in that: The dopant is a nitrogen-containing compound and / or a boron-containing compound.

4. The graphene conductive paste according to claim 3, characterized in that: The nitrogen-containing compound is melamine, ammonia or hydrazine hydrate.

5. The graphene conductive paste according to claim 3, characterized in that: The boron-containing compound is sodium borohydride or boric acid.

6. The graphene conductive paste according to claim 1, 2, 4 or 5, characterized in that: Additives include dispersants, thickeners and surfactants.

7. The graphene conductive paste according to claim 3, characterized in that: Additives include dispersants, thickeners and surfactants.

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