CN113061370A - Graphene ink and preparation method and application thereof - Google Patents

Abstract

The invention discloses graphene ink and a preparation method and application thereof. The graphene ink includes: graphene, an auxiliary agent, a high-length-diameter ratio conductive filler and a dispersion medium; wherein the dispersion medium is selected from low boiling point solvents, the high-length-diameter ratio conductive filler is selected from conductive fillers with length-diameter ratios larger than 1500, and the auxiliary agent is cellulose substances. During preparation, graphite is added into an auxiliary agent/dispersion medium solution, then homogeneous emulsification shearing mixing is carried out, then high-pressure stripping and dispersion are carried out on a dispersion liquid, then a high-length-diameter ratio conductive filler is added, and high-pressure stripping and dispersion are continuously carried out on a system, so that the graphene ink is obtained. The graphene printing ink provided by the invention meets the requirements of printing ink for screen printing, and has the advantages of good electric and thermal conductivity, low cost, simplicity in operation, easiness in amplified production and special patterned customized design.

Description

Graphene ink and preparation method and application thereof

Technical Field

The invention belongs to the technical field of printing ink, and particularly relates to graphene printing ink as well as a preparation method and application thereof.

Background

Graphene is a polymer made of carbon atoms in sp²The two-dimensional carbon nanomaterial composed of the hybrid track has the characteristics of ultra-thin property, ultra-light property, ultra-flexibility, ultra-high strength, ultra-high electrical conductivity, excellent heat conduction and light transmission and the like, integrates various excellent performances of good light transmission, high heat conductivity coefficient, high electron mobility, low resistivity, high mechanical strength and the like, and has wide application prospect in the fields of energy, electronic components, biomedicine and the like.

At present, the most common preparation methods of graphene include a redox method, a mechanical stripping method, an epitaxial growth method and a chemical vapor deposition method, and each method has respective advantages and characteristics. The mechanical stripping method does not destroy the chemical structure of the graphene, can retain the electrical characteristics of the graphene to the maximum extent, and is an ideal way for preparing the high-conductivity graphene. However, in the conventional mechanical exfoliation method, graphene is exfoliated from a graphite material by using mechanical force such as shear force, friction force, tensile force, and the like, and since energy supplied by these mechanical force is limited, it is still difficult to obtain graphene with few layers. It is well known that the performance of graphene decreases dramatically as the number of graphene sheets increases. Although graphene has great application potential, the prior art generally has difficulty in obtaining few-layer graphene, so that the full exertion of the performance of graphene is limited. Therefore, how to prepare few-layer graphene with low cost, high efficiency and high quality is an important issue for studying graphene.

With the generation of modern printed electronics technology, the printed electronics industry based on graphene conductive inks is rapidly developing. The graphene conductive ink is a mixture composed of graphene, a solvent, a binder, an auxiliary agent and the like, and has the advantages of excellent conductivity, light pattern quality, good printability and the like. Compared with nano metal conductive ink, the conductive ink has the advantages of excellent conductivity, lower cost and the like, and has wide application prospect in the fields of printed circuit boards, supercapacitors, sensors and the like. The quality of graphene, which is a key component of graphene conductive ink, determines the performance of the ink.

Disclosure of Invention

The present invention provides a graphene ink comprising: graphene, an auxiliary agent, a high-length-diameter ratio conductive filler and a dispersion medium;

wherein the dispersion medium may be selected from low boiling point solvents, for example from solvents having a boiling point of 30-100 ℃, exemplary from at least one of methanol, ethanol, isopropanol, ethyl acetate and water;

the high aspect ratio conductive filler may be selected from conductive fillers having aspect ratios greater than 1500 (exemplary 1500, 4000, 8000), for example, the high aspect ratio conductive filler may be selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, silver nanowires, and the like;

the auxiliary agent is cellulose substance.

According to an embodiment of the invention, the graphene ink comprises graphene in an amount of 10-80mg/mL, such as 20-60mg/mL, exemplary 20mg/mL, 30mg/mL, 50 mg/mL.

According to an embodiment of the present invention, the number of layers of the graphene is 1 to 10, for example 1 to 5.

According to an embodiment of the present invention, the cellulose-based substance is a nonionic cellulose-based substance, and may be selected from at least one of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose, and nitrocellulose, for example, and is preferably at least one of ethyl cellulose, hydroxyethyl cellulose, and nitrocellulose.

According to an embodiment of the present invention, the content of the auxiliary agent in the graphene ink is 1-30mg/mL, such as 5-25mg/mL, exemplary 5mg/mL, 10mg/mL, 20 mg/mL.

According to an embodiment of the present invention, the content of the conductive filler in the graphene ink is 0.1-10mg/mL, for example, 0.5-8mg/mL, 1-5 mg/mL.

According to an embodiment of the present invention, the graphene ink has a viscosity of 2000-15000 mPaS, such as 3000-12000 mPaS, exemplary 3000 mPaS, 5000 mPaS, 12000 mPaS.

According to an embodiment of the present invention, raw materials for preparing the graphene ink include graphite, an auxiliary agent, a high aspect ratio conductive filler, and a dispersion medium, and the graphite may be selected from at least one of flake graphite and expanded graphite, such as natural flake graphite or vermicular expanded graphite. Further, the graphite is in the form of powder, for example, the mesh number of the graphite powder is 80-1000 meshes, for example, 200-800 meshes, and exemplary 80 meshes, 300 meshes or 600 meshes. Wherein the dispersion medium has the meaning as described above. Further, the adjuvant may be present in the raw materials for preparation in an amount of 1-30mg/mL, such as 5-25mg/mL, illustratively 5mg/mL, 10mg/mL, 20 mg/mL. Further, the graphite content in the raw material for preparation is 10-80mg/mL, for example 20-60mg/mL, illustratively 20mg/mL, 40mg/mL, 50mg/mL, 80 mg/mL.

The invention also provides a preparation method of the graphene ink, which comprises the following steps:

(1) adding graphite into the aid/dispersion medium solution to obtain a graphite dispersion liquid;

(2) homogenizing, emulsifying, shearing and mixing the graphite dispersion liquid to obtain a pretreated graphite dispersion liquid;

(3) and adding the pretreated graphite dispersion liquid into a high-pressure micro-jet homogenizer for high-pressure stripping and dispersion, then adding a high-length-diameter ratio conductive filler, and continuously carrying out high-pressure stripping and dispersion on the system to obtain the graphene ink.

According to an embodiment of the invention, the graphite, the auxiliary agent, the dispersing medium and the high aspect ratio conductive filler all have the meaning as described above.

According to an embodiment of the invention, in step (1), the adjuvant/dispersion medium solution contains 1-30mg/mL, such as 5-25mg/mL, exemplary 5mg/mL, 10mg/mL, 20mg/mL of adjuvant.

According to an embodiment of the invention, in step (1), the graphite dispersion has a graphite content of 10-80mg/mL, such as 20-60mg/mL, exemplary 20mg/mL, 30mg/mL, 50 mg/mL.

According to an embodiment of the present invention, in step (2), the rotation speed of the shear mixing is 500-. Further, the shear mixing time is 30 to 180 minutes, such as 40 to 100 minutes, exemplary 30 minutes or 60 minutes.

According to an embodiment of the present invention, the high-pressure exfoliation and dispersion process of the pretreated graphite dispersion liquid in the step (3) may include: circulating the pretreated graphite dispersion liquid for 5-20 times through a nozzle with the pressure of 2000-15000psi and the thickness of 450 mu m; and circulated through a 100-200 μm nozzle at a flow rate of 150-800m/s (exemplary 150m/s, 300m/s, 800m/s) for 5-40 times at a pressure of 15000-35000 psi. For example, the pretreated graphite dispersion is first circulated 5-15 times (exemplary 5, 10, or 15 cycles) through a 250-400 μm nozzle (exemplary 250 μm nozzle, 300 μm nozzle, or 400 μm nozzle) at a pressure of 3000-10000psi (exemplary 3000psi, 5000psi, 6000psi, 8000psi, or 10000 psi); and then circulated through 100-200 μm nozzles (illustratively 100 μm nozzles, 150 μm nozzles, or 200 μm nozzles) 10-35 times (illustratively 15, 20, or 35 cycles) at 20000-30000psi (illustratively 20000, 25000, or 30000 psi).

According to an embodiment of the present invention, in the step (3), the high-pressure peeling and dispersing process after the high aspect ratio conductive filler is added comprises: the 200-; for example, 300-.

Further, during the above-described high pressure stripping and dispensing process, the flow rate of the liquid through the nozzle is 150-.

According to an embodiment of the invention, in step (3), the high aspect ratio conductive filler is added in an amount of 0.5-10%, such as 0.5-10%, illustratively 0.5%, 5%, 10% of the mass of the graphite.

According to an embodiment of the invention, the dispersion medium and the high aspect ratio conductive filler have the meaning as described above.

According to an embodiment of the present invention, a method for preparing the graphene ink includes the steps of:

(1) mixing and stirring a dispersion medium and an auxiliary agent to prepare an auxiliary agent/dispersion medium solution with the concentration of 5-20 mg/mL; adding 80-1000 mesh graphite into the assistant/dispersion medium solution to prepare graphite dispersion liquid with the concentration of 20-80 mg/mL; shearing and mixing the graphite dispersion liquid for 30-180 minutes by using a homogenizing emulsifying machine at the rotating speed of 500 plus 10000rpm to obtain pretreated graphite dispersion liquid;

(2) adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5-15 times through a nozzle with the diameter of 400 mu m under the pressure of 3000 plus 10000 psi; circulating for 10-35 times through 100-; finally, adding the high length-diameter ratio conductive filler with the mass fraction of 0.1-0.5 percent of the mass of the graphite, and circulating for 1-5 times through a nozzle with the pressure of 1000-4000 psi; and (3) stripping and dispersing under high pressure of a high-pressure pump to obtain the graphene ink.

The invention also provides the graphene ink prepared by the method.

The invention also provides application of the graphene ink in screen printing (such as printed circuit boards), supercapacitors, sensors and the like.

Has the advantages that:

1) the method starts from graphite, and prepares the graphene printing ink in one step by utilizing high-pressure micro-jet. On one hand, the graphite does not need to be treated by a strong oxidizing chemical reagent, so that the prepared graphene has a complete structure, the number of layers of the obtained graphene sheet is small (single-layer or few-layer graphene), the excellent conductivity of the graphene sheet can be fully exerted, and the ink performance is improved; on the other hand, the process does not use high boiling point organic solvent, and is easy for post-treatment; in addition, other impurities are not introduced in the stripping process, and purification treatment is not needed, so that the preparation process is simplified, the cost is reduced, and the method is green and environment-friendly.

2) According to the invention, environment-friendly natural high-molecular cellulose substances such as ethyl cellulose, hydroxyethyl cellulose, nitrocellulose and the like are used as the stripping auxiliary agent, the dispersing agent, the viscosity regulator and the binder, so that the stripping of graphite is facilitated, and the stability of the graphene dispersion liquid is ensured. In addition, the printable graphene ink can be prepared by adjusting the viscosity by adjusting the amount of the natural polymer cellulose substance.

3) The graphene ink provided by the invention meets the requirement of ink suitable for screen printing. In one aspect, circuit patterned custom printing can be achieved by designing a specific pattern in the printing area of the screen. The technology has the advantages of very low equipment cost, simple operation, easy scale-up production and special patterned customized design.

4) The preparation method of the graphene printing ink provided by the invention has the characteristics of environmental friendliness, simple process, low cost, wide applicability and the like, and is suitable for industrial production.

5) The conductive filler with the high yield-diameter ratio, which is fully dispersed in the graphene printing ink, can be matched with the graphene to form a conductive network, so that the conductive capacity of the printing ink is improved, the resistivity of a screen-printed finished product of the graphene printing ink is reduced, and the heating efficiency of the finished product is improved. The graphene ink provided by the invention has wide application prospects in the fields of printed circuit boards, supercapacitors, sensors and the like.

Drawings

Fig. 1 is a raman spectrum of the graphene ink in comparative example 1.

Fig. 2 is a transmission electron microscope image of graphene in the graphene ink in example 1 of the present invention.

Fig. 3 is a diagram of a polyimide graphene film patterned in example 1.

Detailed Description

The technical solution of the present invention will be further described in detail with reference to specific embodiments. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.

Unless otherwise indicated, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

Example 1

(1) Mixing and stirring ethanol and ethyl cellulose to prepare ethyl cellulose/ethanol solution with the concentration of 10 mg/mL; adding 300-mesh flaky graphite into the ethyl cellulose/ethanol solution to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 10 times through a 300-micron nozzle at a flow rate of 300m/s, wherein the pressure is 8000 psi; circulating for 35 times through a 100 μm nozzle at a flow rate of 300m/s and a pressure of 30000 psi; finally, multi-walled carbon nanotubes (aspect ratio: 4000) in an amount of 5% by mass of graphite were added, and the mixture was circulated 5 times through a 300 μm nozzle at a flow rate of 300m/s under a pressure of 4000 psi. And (3) stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the multi-walled carbon nano-tubes, wherein the viscosity of the graphene ink is 5000mPa & S. A transmission electron micrograph of graphene in the graphene ink is shown in fig. 2. The typical lamellar structure of graphene is evident from fig. 2, and has a wrinkling phenomenon.

The graphene ink obtained in this example can be used for screen printing to print a pattern on a polyimide film, and a digital photograph thereof is shown in fig. 3. The patterned polyimide graphene film can be used for manufacturing a heating film.

Example 2

(1) Mixing and stirring ethanol and ethyl cellulose to prepare ethyl cellulose/ethanol solution with the concentration of 10 mg/mL; adding 300-mesh expanded graphite into the ethyl cellulose/ethanol solution to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 10 times through a 300-micron nozzle at a flow rate of 300m/s, wherein the pressure is 8000 psi; circulating for 35 times through a 100 μm nozzle at a flow rate of 300m/s and a pressure of 30000 psi; finally, multi-walled carbon nanotubes (aspect ratio: 4000) in an amount of 5% by mass of graphite were added, and the mixture was circulated 5 times through a 300 μm nozzle at a flow rate of 300m/s under a pressure of 4000 psi. And (3) stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the multi-walled carbon nano-tubes, wherein the viscosity of the graphene ink is 5000mPa & S.

Example 3

(1) Mixing and stirring ethanol and ethyl cellulose to prepare ethyl cellulose/ethanol solution with the concentration of 10 mg/mL; adding 600-mesh expanded graphite into the ethyl cellulose/ethanol solution to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 180 minutes using a homogenizer at 500rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5 times through a 250-micron nozzle at a flow rate of 150m/s, wherein the pressure is 6000 psi; circulating at flow rate of 800m/s through 150 μm nozzle for 20 times under pressure of 20000 psi; finally, single-walled carbon nanotubes (aspect ratio 1500) with a graphite mass fraction of 0.5% were added and circulated through a 400 μm nozzle at a flow rate of 150m/s for 1 cycle at a pressure of 1000 psi. And stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the single-walled carbon nanotubes, wherein the viscosity of the graphene ink is 3000mPa & S.

Example 4

(1) Mixing and stirring methanol and ethyl cellulose to prepare ethyl cellulose/methanol solution with the concentration of 5 mg/mL; adding 80-mesh expanded graphite into the ethyl cellulose/methanol solution to prepare graphite dispersion liquid with the concentration of 20 mg/mL; the graphite dispersion was shear-mixed for 180 minutes using a homogenizer at 500rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5 times through a 250-micron nozzle at a flow rate of 800m/s, wherein the pressure is 3000 psi; circulating at flow rate of 800m/s through 150 μm nozzle for 20 times under pressure of 20000 psi; finally, single-walled carbon nanotubes (aspect ratio 8000) of graphite mass fraction 0.5% were added and circulated 5 times through a 500 μm nozzle at a flow rate of 150m/s under a pressure of 1000 psi. And stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the single-walled carbon nanotubes, wherein the viscosity of the graphene ink is 12000mPa & S.

Example 5

(1) Mixing and stirring isopropanol and ethyl cellulose to prepare ethyl cellulose/isopropanol solution with the concentration of 20 mg/mL; adding 1000-mesh flaky graphite into the ethyl cellulose/isopropanol solution to prepare graphite dispersion liquid with the concentration of 80 mg/mL; the graphite dispersion was shear-mixed for 30 minutes using a homogenizer at 10000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5 times through a 400-micron nozzle at a flow rate of 300m/s, wherein the pressure is 3000 psi; circulating 10 times through 200 μm nozzle at flow rate of 300m/s under pressure of 20000 psi; finally, silver nanowires (length-diameter ratio 4000) with a mass fraction of 10% of graphite mass were added, and the mixture was circulated through a 500 μm nozzle at a flow rate of 300m/s for 3 times at a pressure of 1000 psi. And stripping, dispersing and heating and concentrating under high pressure by a high-pressure pump to obtain the graphene ink containing the silver nanowires, wherein the viscosity of the graphene ink is 12000mPa & S.

Example 6

(1) Mixing and stirring water and hydroxyethyl cellulose to prepare a hydroxyethyl cellulose/water solution with the concentration of 20 mg/mL; adding 300-mesh expanded graphite into the hydroxyethyl cellulose/water solution to prepare a graphite dispersion liquid with the concentration of 20 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 15 times through a 300-micron nozzle at a flow rate of 150m/s, wherein the pressure is 10000 psi; circulating at flow rate of 150m/s through 200 μm nozzle for 20 times at pressure of 25000 psi; finally, silver nanowires (aspect ratio 1500) with a mass fraction of 10% of the graphite mass were added and circulated 5 times through a 400 μm nozzle at a flow rate of 150m/s and a pressure of 2500 psi. And stripping, dispersing and heating and concentrating under high pressure by a high-pressure pump to obtain the graphene ink containing the silver nanowires, wherein the viscosity of the graphene ink is 5000mPa & S.

Example 7

(1) Mixing the following components in a mass ratio of 1: 1, mixing and stirring the ethanol and ethyl acetate mixed solution and ethyl cellulose to prepare an ethyl cellulose/mixed solution with the concentration of 20 mg/mL; adding 80-mesh flaky graphite into the ethyl cellulose/mixed solution to prepare graphite dispersion liquid with the concentration of 20 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 10000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating 15 times through a 250-micrometer nozzle at a flow rate of 800m/s under a pressure of 3000 psi; circulating at a flow rate of 800m/s through a nozzle of 100 μm for 20 times under a pressure of 20000 psi; finally, multi-walled carbon nanotubes (aspect ratio 4000) of 5% graphite mass by mass were added and circulated 5 times through a 400 μm nozzle at a flow rate of 800m/s at a pressure of 2500 psi. And (3) stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the multi-walled carbon nanotubes, wherein the viscosity of the graphene ink is 3000mPa & S.

Example 8

(1) Mixing and stirring ethyl acetate and nitrocellulose, and preparing nitrocellulose/ethyl acetate solution with the concentration of 20 mg/mL; mixing the following components in a mass ratio of 1: adding 300-mesh flaky graphite and 300-mesh expanded graphite of 1 into the nitrocellulose/ethyl acetate solution to prepare a graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5 times through a 300-micron nozzle at a flow rate of 150m/s, wherein the pressure is 10000 psi; circulating at flow rate of 300m/s through 150 μm nozzle for 20 times under pressure of 20000 psi; finally, multi-walled carbon nanotubes (length-diameter ratio of 4000) with the mass fraction of 0.1 graphite mass and silver nanowires (length-diameter ratio of 1500) with the mass fraction of 0.5% graphite mass are added, and the mixture is circulated for 3 times through a 500-micron nozzle at the flow rate of 800m/s, and the pressure is 1000 psi. And (3) stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the multi-walled carbon nano-tubes and the silver nanowires, wherein the viscosity of the graphene ink is 5000mPa & S.

Comparative example 1

(1) Mixing and stirring ethanol and ethyl cellulose to prepare ethyl cellulose/ethanol solution with the concentration of 10 mg/mL; adding 300-mesh flaky graphite into the ethyl cellulose/ethanol solution to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 10 times through a 300-micron nozzle at a flow rate of 300m/s, wherein the pressure is 8000 psi; and circulated through a 100 μm nozzle at a flow rate of 300m/s for 35 times at a pressure of 30000 psi. And stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink with the viscosity of 5000mPa & S.

The raman spectrum of the graphene ink is shown in fig. 1. As can be seen from the data in fig. 1, the ratio of the D peak to the G peak of the graphene prepared by the high-pressure microjet is 0.55, and the 2D peak is a sharp single peak, so that it can be judged that the number of layers of the prepared graphene is between 1 and 5, and the graphene has a good peeling effect.

Comparative example 2

(1) Adding 300-mesh expanded graphite into ethanol to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 10 times through a 300-micron nozzle at a flow rate of 300m/s, wherein the pressure is 8000 psi; circulating for 35 times through a 100 μm nozzle at a flow rate of 300m/s and a pressure of 30000 psi; finally, multi-walled carbon nanotubes (length-diameter ratio: 4000) with a mass fraction of 5% of the graphite mass were added, and the mixture was circulated 5 times through a 300 μm nozzle at a flow rate of 300m/s under a pressure of 4000 psi. And (3) stripping and dispersing under high pressure by a high-pressure pump, and heating and concentrating to obtain the graphene ink containing the multi-walled carbon nano-tubes, wherein the viscosity of the graphene ink is 5000mPa & S.

Comparative example 4

(1) Mixing and stirring ethanol and ethyl cellulose to prepare ethyl cellulose/ethanol solution with the concentration of 10 mg/mL; adding 300-mesh expanded graphite into the ethyl cellulose/ethanol solution to prepare graphite dispersion liquid with the concentration of 50 mg/mL; the graphite dispersion was shear-mixed for 60 minutes using a homogenizer at 5000rpm to obtain a pretreated graphite dispersion.

(2) Adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 10 times through a 300-micron nozzle at a flow rate of 300m/s, wherein the pressure is 8000 psi; circulating for 35 times through a 100 μm nozzle at a flow rate of 300m/s and a pressure of 30000 psi; finally, multi-walled carbon nanotubes (length-diameter ratio: 4000) with a mass fraction of 5% of the graphite mass were added, and the mixture was circulated 5 times through a 300 μm nozzle at a flow rate of 300m/s under a pressure of 4000 psi. And (3) stripping under high pressure by a high-pressure pump, dispersing, heating and concentrating to obtain the graphene ink containing the multi-walled carbon nano-tubes, wherein the viscosity of the graphene ink is 5000mPa & S. The Raman spectrum is shown in FIG. 2.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A graphene ink, wherein the graphene ink comprises: graphene, an auxiliary agent, a high-length-diameter ratio conductive filler and a dispersion medium;

wherein the dispersion medium is selected from low boiling point solvents, the high-length-diameter ratio conductive filler is selected from conductive fillers with length-diameter ratios larger than 1500, and the auxiliary agent is cellulose substances.

2. The graphene ink according to claim 1, wherein the dispersion medium is selected from a solvent having a boiling point of 30-100 ℃, preferably at least one selected from methanol, ethanol, isopropanol, ethyl acetate and water;

preferably, the high aspect ratio conductive filler is selected from at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and silver nanowires;

preferably, the cellulose-based substance is a nonionic cellulose-based substance, preferably at least one selected from the group consisting of ethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxymethyl cellulose and nitrocellulose.

3. The graphene ink according to claim 1 or 2, wherein the graphene ink contains 10-80mg/mL of graphene;

preferably, the number of layers of the graphene is 1-10;

preferably, in the graphene ink, the content of the auxiliary agent is 1-30 mg/mL;

preferably, in the graphene ink, the content of the high aspect ratio conductive filler is 0.1-10 mg/mL;

preferably, the viscosity of the graphene ink is 2000-15000mPa · S.

4. The graphene ink according to any one of claims 1 to 3, wherein the raw materials for preparing the graphene ink comprise graphite, an auxiliary agent, a high aspect ratio conductive filler and a dispersion medium;

preferably, the graphite is selected from at least one of flaky graphite and expanded graphite.

5. The method for preparing the graphene ink according to any one of claims 1 to 4, comprising the steps of:

(1) adding graphite into the aid/dispersion medium solution to obtain a graphite dispersion liquid;

(2) homogenizing, emulsifying, shearing and mixing the graphite dispersion liquid to obtain a pretreated graphite dispersion liquid;

(3) and adding the pretreated graphite dispersion liquid into a high-pressure micro-jet homogenizer for high-pressure stripping and dispersion, then adding a high-length-diameter ratio conductive filler, and continuously carrying out high-pressure stripping and dispersion on the system to obtain the graphene ink.

6. The method for preparing the graphene ink according to claim 5, wherein in the step (1), the content of the auxiliary agent in the auxiliary agent/dispersion medium solution is 1-30 mg/mL;

preferably, in the step (1), the content of graphite in the graphite dispersion liquid is 10-80 mg/mL.

Preferably, in the step (2), the rotation speed of the shear mixing is 500-10000 rpm; preferably, the time of shear mixing is 30 to 180 minutes.

7. The method for preparing the graphene ink according to claim 5 or 6, wherein the high-pressure exfoliation and dispersion process of the pretreated graphite dispersion liquid in the step (3) comprises: circulating the pretreated graphite dispersion liquid for 5-20 times through a nozzle with the pressure of 2000-15000psi and the thickness of 450 mu m; circulating the mixture through a 100-200 μm nozzle at a flow rate of 150-800m/s for 5-40 times at a pressure of 15000-35000 psi;

preferably, in step (3), the high-pressure peeling and dispersing process after adding the high aspect ratio conductive filler comprises: the 200-;

preferably, the flow rate of the liquid passing through the nozzle during the high pressure stripping and dispersion process is 150-;

preferably, in step (3), the high aspect ratio conductive filler is added in an amount of 0.5-10% by mass of the graphite.

8. The method for preparing the graphene ink according to any one of claims 5 to 7, comprising the steps of:

(1) mixing and stirring a dispersion medium and an auxiliary agent to prepare an auxiliary agent/dispersion medium solution with the concentration of 5-20 mg/mL; adding 80-1000 mesh graphite into the aid/dispersion medium solution to prepare graphite dispersion liquid with the concentration of 20-80 mg/mL; shearing and mixing the graphite dispersion liquid for 30-180 minutes by using a homogenizing emulsifying machine at the rotating speed of 500 plus 10000rpm to obtain pretreated graphite dispersion liquid;

(2) adding the pretreated graphite dispersion liquid into a feeding cup of a high-pressure micro-jet homogenizer, and circulating for 5-15 times through a nozzle with the diameter of 400 mu m under the pressure of 3000 plus 10000 psi; circulating for 10-35 times through 100-; finally, adding the high length-diameter ratio conductive filler with the mass fraction of 0.1-0.5 percent of the mass of the graphite, and circulating for 1-5 times through a nozzle with the pressure of 1000-4000 psi; and (3) stripping and dispersing under high pressure of a high-pressure pump to obtain the graphene ink.

9. Graphene ink prepared by the method of any one of claims 5 to 8.

10. Use of the graphene ink according to any one of claims 1 to 4 or 9 in screen printing, supercapacitors or sensors.

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