CN113036143A

CN113036143A - Preparation method of graphene composite conductive slurry

Info

Publication number: CN113036143A
Application number: CN202110261050.5A
Authority: CN
Inventors: 姜鹏; 冯晓彤; 何斌; 马洪伟
Original assignee: Harbin Wanxin Graphite Valley Technology Co ltd
Current assignee: Harbin Wanxin Graphite Valley Technology Co ltd
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2021-06-25

Abstract

The invention provides a preparation method of graphene composite conductive slurry. The preparation method comprises the following steps: (1) respectively preparing carbon nanotube slurry, graphene oxide slurry and conductive carbon black slurry; (2) mixing the carbon nanotube slurry and the graphene oxide slurry, adding conductive carbon black slurry, and stirring to obtain graphene composite conductive slurry; the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1 (1-10) to 1-10. According to the invention, the carbon nanotube slurry, the graphene oxide slurry and the conductive carbon black slurry are respectively prepared, and then the carbon nanotube slurry, the graphene oxide slurry and the conductive carbon black slurry are mixed according to a proper proportion, so that the obtained composite slurry is uniform and stable, is suitable for a lithium ion battery additive, and improves the charge and discharge performance of the lithium ion battery.

Description

Preparation method of graphene composite conductive slurry

Technical Field

The invention relates to the technical field of battery manufacturing, in particular to a preparation method of graphene composite conductive slurry.

Background

With the development of industrial technology, new environmental-friendly energy materials are attracting more and more attention, and lithium ion batteries are widely applied to the fields of mobile phone batteries, new energy automobiles, computers, medium and small energy storage systems and the like as green energy at the present stage due to the advantages of high capacity, portability, safety, long cycle life and the like. The cycle life of the lithium ion battery can be prolonged and the performance of the battery can be effectively improved after the Carbon Nano Tube (CNT) is added into the lithium ion battery.

The CNT conductive paste is a novel high-efficiency conductive agent for a lithium battery, can replace the traditional conductive agents such as traditional conductive carbon black, conductive graphite, conductive carbon fiber and the like, has the superior characteristics of ultrahigh length-diameter ratio, ultrahigh specific surface area, ultralow volume resistivity and the like, can be applied to various electrode materials such as LFP, LCO, LMN, NCM, graphite and the like, has the addition amount of only 0.5-1%, can obviously reduce the internal resistance of the battery, improves the gram volume exertion of active materials, obviously reduces the consumption of the conductive agent and the consumption of a binder, improves the high-current discharge power density, enhances the absorption of electrolyte and prolongs the service life.

For example, CN110176623A discloses a method for preparing a lithium ion battery, which comprises the following steps: (1) mixing a positive electrode active material, CNT-containing conductive slurry, a binder and a solvent to prepare positive electrode slurry, and coating the positive electrode slurry on a positive electrode current collector to obtain a positive electrode piece; (2) mixing a negative electrode active material, CNT-containing conductive slurry, a binder and a solvent to prepare negative electrode slurry, and coating the negative electrode slurry on a negative electrode current collector to obtain a negative electrode plate; (3) and assembling the lithium ion battery by using the positive pole piece, the negative pole piece, the diaphragm and the electrolyte. The preparation method of the lithium ion battery provided by the invention starts with the improvement of the conductivity of the battery pole piece, and the conductive agent containing the CNT is added into the pole piece, so that the active material ratio of the battery pole piece is improved. The method is generally applicable to various battery material systems, is simple to manufacture and is easy to realize large-scale industrial production.

However, the CNT conductive paste is prone to have problems of non-uniform dispersion, poor settling degree and the like during the preparation process, and further affects the cycle performance of the battery. Therefore, the conductive paste with better performance is provided, and has important influence on the preparation of the lithium ion battery.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a preparation method of graphene composite conductive paste, the preparation method is simple in process, the materials are matched in proportion, and the obtained conductive paste is excellent in performance and suitable for large-scale production.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a preparation method of a graphene composite conductive paste, where the preparation method includes:

(1) respectively preparing Carbon Nano Tube (CNT) slurry, Graphene Oxide (GO) slurry and conductive carbon black (SP) slurry;

(2) mixing the carbon nanotube slurry and the graphene oxide slurry, adding conductive carbon black slurry, and stirring to obtain graphene composite conductive slurry;

the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1 (1-10) to 1-10.

The invention mainly introduces a preparation method of graphene composite conductive slurry, which has the advantages of simple process, low cost and suitability for mass production, and can be suitable for a lithium ion battery additive and improve the charge and discharge performance of the lithium ion battery through reasonable matching of carbon nanotube slurry, graphene oxide slurry and conductive carbon black slurry.

Compared with the slurry prepared by a sanding composite processing mode, the conductive slurry prepared by the processing mode can effectively improve the sedimentation degree of the slurry, can effectively improve the cycle performance of a battery when being used as a conductive material of a lithium ion battery, simultaneously reduces the processing procedures of semi-finished products, and can effectively improve the mass production efficiency. The raw materials used in the invention have high purity and good processability, and the prepared slurry is stable and uniform and has the particle size distribution D504-5 μm.

In the invention, the weight ratio of the carbon nanotube slurry, the graphene oxide slurry and the conductive carbon black slurry may be 1:1:1, 1:1:2, 1:1:5, 1:1:8, 1:1:10, 1:2:1, 1:5:1, 1:8:1, 1:10:1, 1:2:2, 1:4:6, 1:5:5, 1:6:8, 1:5:7, 1:5:10, 1:8:9 or 1:10:10, and preferably 1:6: 3.

As a preferable embodiment of the present invention, the solid content of the carbon nanotube slurry in the step (1) is not more than 6%, and may be, for example, 1%, 1.5%, 2%, 3%, 3.5%, 4%, 5%, 6%, or the like.

Preferably, the solid content of the graphene oxide slurry in the step (1) is less than or equal to 6%, and may be, for example, 1%, 1.5%, 2%, 3%, 3.5%, 4%, 5%, 6%, and the like.

Preferably, the conductive carbon black slurry in the step (1) has a solid content of 9% or less, and may be, for example, 1%, 1.5%, 2%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, or the like.

Preferably, the particle diameter D50 of the carbon nanotubes in the carbon nanotube slurry of step (1) is 0.1 to 0.3 μm, and may be, for example, 0.1 μm, 0.12 μm, 0.15 μm, 0.2 μm, 0.22 μm, 0.25 μm, 0.28 μm, or 0.3 μm.

Preferably, the particle size D50 of the graphene oxide slurry in step (1) is 0.1 to 0.3 μm, and may be, for example, 0.1 μm, 0.12 μm, 0.15 μm, 0.2 μm, 0.22 μm, 0.25 μm, 0.28 μm, or 0.3 μm.

Preferably, the particle diameter D50 of the conductive carbon black slurry in the step (1) is 0.6-0.9 μm, and may be, for example, 0.6 μm, 0.62 μm, 0.65 μm, 0.7 μm, 0.72 μm, 0.75 μm, 078 μm or 0.9 μm.

Preferably, the rotation speed of the stirring in the step (2) is 1000-2000 r/min, such as 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min, 1500r/min, 1600r/min, 1700r/min, 1800r/min, 1900r/min or 2000 r/min.

Preferably, the stirring time in step (2) is 15-30 min, such as 15min, 16min, 18min, 20min, 22min, 25min, 26min, 28min or 30 min.

As a preferable technical scheme of the invention, the carbon nanotubes in the carbon nanotube slurry in the step (1) are multi-walled carbon nanotubes.

Preferably, the carbon nanotube slurry of step (1) includes arrayed carbon nanotubes and/or wound carbon nanotubes (ZFH).

Preferably, the carbon nanotube conductive paste of step (1) includes 3% to 6% (e.g., 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 5.8%, 6%, etc.) of carbon nanotubes, 0.6% to 1.5% (e.g., 0.6%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, etc.) of a dispersant, and the balance of an oily solvent.

Preferably, the preparation method of the carbon nanotube conductive paste of step (1) comprises:

adding the carbon nano tube, the dispersing agent and the oily solvent into a ball mill, grinding, and then putting the ground slurry into a sand mill, and sanding until the particle size D50 is 0.1-0.3 mu m.

Preferably, the dispersant comprises polyvinylpyrrolidone.

Preferably, the oily solvent comprises N-methylpyrrolidone (NMP).

Preferably, the particle size D50 of the slurry after grinding is 3 to 5 μm, and may be, for example, 3 μm, 3.2 μm, 3.5 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, or 5 μm.

In a preferred embodiment of the present invention, the graphene oxide slurry in step (1) includes 3% to 6% (e.g., 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 5.8%, 6%, etc.) of graphene oxide, 0.6% to 1.5% (e.g., 0.6%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, etc.) of a dispersant, and the balance of an oily solvent, in terms of mass%.

Preferably, the conductive carbon black slurry comprises, by mass, 6% to 8% (for example, 6%, 6.2%, 6.4%, 6.5%, 7%, 7.2%, 7.5%, 7.8%, 8%, etc.) of conductive carbon black, 2% to 4% (for example, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.3%, 1.4%, 1.5%, etc.) of a dispersant, and the balance of an oily solvent.

As a preferable technical solution of the present invention, the preparation method of the graphene oxide slurry in the step (1) includes: putting the powdered graphene oxide, a dispersing agent and an oily solvent into processing equipment, treating until D50 is less than 50 microns, and treating under the pressure of 10-13 kPa until D50 is less than 2 microns.

Preferably, the preparation method of the conductive carbon black slurry in the step (1) comprises the following steps: adding powdery conductive carbon black, a dispersing agent and an oily solvent into a ball mill, grinding until D50 is less than 50 mu m, then putting the ground slurry into a sand mill, and sanding until the particle size D50 is 0.6-0.9 mu m;

preferably, the rotation speed of the sand mill is 1000-1500 r/min, such as 1000r/min, 1100r/min, 1200r/min, 1300r/min, 1400r/min or 1500 r/min.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(1) respectively preparing carbon nanotube slurry, graphene oxide slurry and conductive carbon black slurry, wherein the solid content of the carbon nanotube slurry is less than or equal to 6%, the solid content of the graphene oxide slurry is less than or equal to 6%, and the solid content of the conductive carbon black slurry is less than or equal to 9%;

the preparation method of the carbon nano tube conductive slurry comprises the following steps: adding a carbon nano tube, polyvinylpyrrolidone and N-methyl pyrrolidone into a ball mill, and grinding, wherein the particle size D50 of the ground slurry is 3-5 mu m; putting the ground slurry into a sand mill, and sanding until the particle size D50 is 0.1-0.3 mu m;

(2) mixing the carbon nanotube slurry and the graphene oxide slurry, adding conductive carbon black slurry, and stirring at 1000-2000 r/min for 15-30 min to obtain graphene composite conductive slurry;

wherein the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is (1-10): 1.

In a second aspect, the present invention provides a graphene composite conductive paste prepared by the preparation method according to the first aspect.

In a third aspect, the invention provides an application of the graphene composite conductive paste according to the second aspect in preparation of a lithium ion battery.

The recitation of numerical ranges herein includes not only the above-recited values, but also any values between any of the above-recited numerical ranges not recited, and for brevity and clarity, is not intended to be exhaustive of the specific values encompassed within the range.

Compared with the prior art, the invention has at least the following beneficial effects:

the invention provides a preparation method of graphene composite conductive slurry, which comprises the steps of respectively preparing carbon nanotube slurry, graphene oxide slurry and conductive carbon black slurry, and mixing the carbon nanotube slurry, the graphene oxide slurry and the conductive carbon black slurry according to a proper proportion, wherein the obtained composite slurry is uniform and stable, and the preparation requirement of the composite conductive slurry with higher cost performance is met; and after the carbon nanotube conductive slurry is subjected to sanding, the performance of the obtained graphene composite conductive slurry is better, the viscosity of the obtained composite conductive slurry fluctuates between 300 and 950 mPa.s, and the fineness of the obtained composite conductive slurry fluctuates between 10 and 15 mu m.

Meanwhile, the preparation method has sufficient raw materials and low cost, and solves the problems of high production cost of factories and the like. Therefore, the preparation method provided by the invention has better performance when being used as a lithium ion battery material, reduces the cost and is suitable for industrial mass production.

Drawings

Fig. 1 is a graph showing capacity retention rates of lithium ion batteries prepared from the composite pastes obtained in example 1, example 2 and comparative example 1.

Detailed Description

The technical solutions of the present invention are further described in the following embodiments with reference to the drawings, but the following examples are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

In the following examples, unless otherwise specified, reagents and consumables were purchased from conventional reagent manufacturers in the field; unless otherwise indicated, all experimental methods and technical means used are those conventional in the art.

Example 1

The embodiment provides a preparation method of graphene composite conductive paste, which specifically comprises the following steps:

(1) respectively preparing carbon nanotube slurry, graphene oxide slurry and conductive carbon black slurry;

a. preparing carbon nanotube slurry: adding the array carbon nano tube, the dispersing agent and the oily solvent into a ball mill, processing for 2 hours at 50Hz, wherein the particle size D50 is 3.5 mu m, and then putting the slurry obtained after grinding into a sand mill, and sanding until the particle size D50 is 0.3 mu m;

the obtained graphene oxide slurry comprises 5% of graphene oxide, 1% of a dispersant and the balance of an oily solvent in percentage by mass;

b. preparing graphene oxide slurry: putting the powdered graphene oxide, a dispersing agent and an oily solvent into a ball mill, treating for 5 hours until D50 is less than 50 microns, and then treating for 2 hours under the pressure of 10 kPa;

wherein the particle size D50 of the slurry after the first step of treatment is less than 50 μm, and the particle size D50 of the slurry after the second step of treatment is 0.2 μm;

c. preparing conductive carbon black slurry: adding powdery conductive carbon black, a dispersing agent and an oily solvent into a ball mill, grinding until D50 is less than 50 mu m, then putting the ground slurry into a sand mill at the rotating speed of 1200r/min, and sanding;

wherein the particle size D50 of the ground slurry is less than 50 μm, and the particle size of the ground slurry is 0.8 μm;

the obtained conductive carbon black slurry comprises, by mass, 8% of conductive carbon black, 2% of a dispersant and the balance of an oily solvent;

(2) and mixing the carbon nanotube slurry and the graphene oxide slurry, and adding conductive carbon black slurry, wherein the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1:6:3, and stirring at 1500r/min for 20min to obtain the graphene composite conductive slurry.

Example 2

The embodiment provides a preparation method of graphene composite conductive paste, which is different from embodiment 1 in that an array type carbon nanotube is replaced by a winding type carbon nanotube; the remaining preparation methods and parameters were in accordance with example 1.

Example 3

a. preparing carbon nanotube slurry: adding the array carbon nano tube, the dispersing agent and the oily solvent into a ball mill, processing for 2 hours at 50Hz, wherein the particle size D50 is 3 mu m, and then putting the slurry obtained after grinding into a sand mill, and sanding until the particle size D50 is 0.1 mu m;

the obtained graphene oxide slurry comprises, by mass, 6% of graphene oxide, 1% of a dispersant, and the balance of an oily solvent;

b. preparing graphene oxide slurry: putting the powdered graphene oxide, a dispersing agent and an oily solvent into a ball mill, treating for 5 hours until D50 is less than 50 mu m, and then treating for 2 hours under the pressure of 13 kPa;

wherein the particle size D50 of the slurry after the first step of treatment is less than 50 μm, and the particle size D50 of the slurry after the second step of treatment is 0.1 μm;

wherein the particle size D50 of the ground slurry is less than 50 μm, and the particle size of the ground slurry is 0.6 μm;

(2) and mixing the carbon nanotube slurry and the graphene oxide slurry, and adding conductive carbon black slurry, wherein the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1:2:8, and stirring at 1000r/min for 30min to obtain the graphene composite conductive slurry.

Example 4

a. preparing carbon nanotube slurry: adding the array carbon nano tube, the dispersing agent and the oily solvent into a ball mill, processing for 2 hours at 50Hz, wherein the particle size D50 is 5 mu m, and then putting the slurry obtained after grinding into a sand mill, and sanding until the particle size D50 is 0.3 mu m;

b. preparing graphene oxide slurry: putting the powdered graphene oxide, a dispersing agent and an oily solvent into a ball mill, treating for 5 hours until D50 is less than 50 microns, and then treating for 2 hours under the pressure of 12 kPa;

wherein the particle size D50 of the slurry after the first step of treatment is less than 50 μm, and the particle size D50 of the slurry after the second step of treatment is 0.3 μm;

wherein the particle size D50 of the ground slurry is less than 50 μm, and the particle size of the ground slurry is 0.9 μm;

(2) and mixing the carbon nanotube slurry and the graphene oxide slurry, and adding conductive carbon black slurry, wherein the weight ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1:8:2, and stirring at 1500r/min for 20min to obtain the graphene composite conductive slurry.

Example 5

The embodiment provides a preparation method of graphene composite conductive paste, which is different from embodiment 1 in that in step (2), the weight ratio of carbon nanotube paste, graphene oxide paste and conductive carbon black paste is adjusted to 1:1: 10;

the remaining preparation methods and parameters were in accordance with example 1.

Example 6

The embodiment provides a preparation method of graphene composite conductive paste, which is different from embodiment 1 in that in step (2), the weight ratio of carbon nanotube paste, graphene oxide paste and conductive carbon black paste is adjusted to 1:10: 1;

Example 7

The embodiment provides a preparation method of graphene composite conductive paste, which is different from embodiment 1 in that in step (1), the carbon nanotube paste is not subjected to sanding, and the particle size D50 is 3.5 μm;

Comparative example 1

The comparative example provides a preparation method of graphene composite conductive paste, which is different from that of example 1 in that carbon nanotubes are not added in the paste, and the weight ratio of graphene oxide paste to conductive carbon black paste is adjusted to 7: 3;

Comparative example 2

The present comparative example provides a method for preparing a graphene composite conductive paste, which is different from example 1 in that, in step (2), the weight ratio of the carbon nanotube paste, the graphene oxide paste, and the conductive carbon black paste is adjusted to 1:0.5: 3;

Comparative example 3

The present comparative example provides a method for preparing a graphene composite conductive paste, which is different from example 1 in that, in step (2), the weight ratio of the carbon nanotube paste, the graphene oxide paste, and the conductive carbon black paste is adjusted to 1:6: 11;

Comparative example 4

The comparative example provides a preparation method of graphene composite conductive paste, and is different from the embodiment 1 in that preparation raw materials are directly mixed, sanding is carried out at 1200r/min for 2h, and then stirring is carried out at 1500r/min for 20 min;

Performance testing

1. The invention expresses the dispersibility and consistency of the slurry through the fluctuation range of the viscosity and fineness of the slurry, and the dispersibility and consistency of the slurry are good if the fluctuation range is small.

Wherein, the viscosity is measured by a viscometer, and the fineness is measured by a scraper fineness meter;

the specific results are shown in table 1 below:

TABLE 1

Sample (I)	Fluctuation range of viscosity (mPa. s)	Fluctuation range of fineness (mum)
			Example 1	400-500	10-12
Example 2	400-500	12-14
			Example 3	600-800	10-12
Example 4	300-500	12-15
			Example 5	700-950	11-13
Example 6	300-450	10-13
			Example 7	1000-1300	14-16
Comparative example 1	350-500	11-13
			Comparative example 2	800-1000	11-13
Comparative example 3	300-400	14-17
			Comparative example 4	1200-1450	14-17

As can be seen from the above table, the composite conductive paste prepared by the method of example 1 has low viscosity, low fineness, reasonable preparation process, high efficiency and best uniformity of the paste;

as can be seen from the comparison between the embodiment 1 and the embodiment 2, the viscosity fluctuation ranges of the graphene composite conductive paste prepared by the array type carbon nanotubes or the winding type carbon nanotubes are both 400-500mPa · s, and the fineness fluctuation ranges are relatively similar, wherein the embodiment 1 is 10-12 μm, and the embodiment 2 is 12-14 μm;

as can be seen from the comparison among the examples 1, 5 to 6 and the comparative examples 2 to 3, when the mass ratio of the carbon nanotube slurry to the graphene oxide slurry to the conductive carbon black slurry is 1 (1 to 10) to (1 to 10), the properties of the obtained composite conductive slurry are stable, and when the mass of any one of the slurries exceeds the range, the fluctuation of fineness and viscosity is obvious, and the conductivity of the composite slurry is poor; the composite conductive paste obtained in example 5 and comparative example 2 has relatively high viscosity, so that the composite conductive paste is more difficult to use and is not beneficial to the preparation of batteries;

as can be seen from the comparison between example 1 and example 7, the carbon nanotube slurry in the preparation method does not undergo sanding, the obtained slurry has low processing efficiency, poor conductivity, and poor cycle performance of the obtained battery;

similarly, as can be seen from comparison of example 1 with comparative example 4, when the preparation raw materials were directly mixed and sanded, the resulting slurry was poor in conductivity and more liable to settle.

2. In the invention, the composite slurry prepared in the embodiment 1, the embodiment 2 and the comparative example 1 is also used for preparing a lithium ion battery, and the capacity retention rate of the lithium ion battery is measured;

the results obtained are shown in FIG. 1;

as can be seen from the figure, after multiple cycles, the capacity retention rate of the battery prepared from the composite slurry provided in comparative example 1 is most obviously reduced, and the performance is poor; the slurry prepared by the invention can improve the sedimentation degree of the slurry, and can effectively improve the cycle performance of the battery when being used as a conductive material of the lithium ion battery.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.

Claims

1. The preparation method of the graphene composite conductive paste is characterized by comprising the following steps:

2. The preparation method according to claim 1, wherein the solid content of the carbon nanotube slurry in the step (1) is less than or equal to 6%;

preferably, the solid content of the graphene oxide slurry in the step (1) is less than or equal to 6 percent;

preferably, the solid content of the conductive carbon black slurry in the step (1) is less than or equal to 9 percent;

preferably, the particle size D50 of the carbon nanotubes in the carbon nanotube slurry in the step (1) is 0.1-0.3 μm;

preferably, the particle size D50 of the graphene oxide slurry in the step (1) is 0.1-0.3 μm;

preferably, the particle size D50 of the conductive carbon black slurry in the step (1) is 0.6-0.9 μm.

3. The preparation method according to claim 1 or 2, wherein the rotation speed of the stirring in the step (2) is 1000 to 2000 r/min;

preferably, the stirring time in the step (2) is 15-30 min.

4. The method according to any one of claims 1 to 3, wherein the carbon nanotubes in the carbon nanotube slurry of step (1) are multi-walled carbon nanotubes;

preferably, the carbon nanotube slurry of step (1) comprises arrayed carbon nanotubes and/or wound carbon nanotubes;

preferably, the carbon nanotube conductive slurry in the step (1) comprises, by mass, 3% to 6% of the carbon nanotubes, 0.6% to 1.5% of a dispersant, and the balance of an oily solvent.

5. The method according to any one of claims 1 to 4, wherein the method for preparing the carbon nanotube conductive paste of step (1) comprises:

adding a carbon nano tube, a dispersing agent and an oily solvent into a ball mill, grinding, and then putting the ground slurry into a sand mill, and sanding until the particle size D50 is 0.1-0.3 mu m;

preferably, the dispersant comprises polyvinylpyrrolidone;

preferably, the oily solvent comprises N-methylpyrrolidone;

preferably, the particle size D50 of the ground slurry is 3-5 μm.

6. The preparation method according to any one of claims 1 to 5, wherein the graphene oxide slurry in the step (1) comprises 3 to 6% by mass of graphene oxide, 0.6 to 1.5% by mass of a dispersant, and the balance of an oily solvent;

preferably, the preparation method of the graphene oxide slurry in the step (1) comprises the following steps:

putting the powdered graphene oxide, a dispersing agent and an oily solvent into processing equipment, treating until D50 is less than 50 microns, and treating under the pressure of 10-13 kPa until D50 is less than 2 microns.

7. The preparation method according to any one of claims 1 to 6, characterized in that the conductive carbon black slurry in the step (1) comprises, by mass, 6% to 8% of conductive carbon black, 2% to 4% of a dispersant, and the balance of an oily solvent;

preferably, the preparation method of the conductive carbon black slurry in the step (1) comprises the following steps:

adding powdery conductive carbon black, a dispersing agent and an oily solvent into a ball mill, grinding until D50 is less than 50 mu m, then putting the ground slurry into a sand mill, and sanding until the particle size D50 is 0.6-0.9 mu m;

preferably, the rotating speed of the sand mill is 1000-1500 r/min.

8. The production method according to any one of claims 1 to 7, characterized by comprising the steps of:

9. Graphene composite conductive paste prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the graphene composite conductive paste according to claim 9 in the preparation of a lithium ion battery.