Prime coat slurry for positive electrode of lithium battery and preparation method of prime coat coating

Abstract

The invention discloses prime coat slurry for a positive electrode of a lithium battery and a preparation method of a prime coat coating. The prime coat slurry is prepared from the following components in percentage by mass: 4-5% of a conductive agent, 5-6% of a binder, 14-16% of an alcohol solvent and the balance of deionized water, wherein the conductive agent is composed of spherical conductive carbon black, flaky conductive graphite, carbon nanotubes and graphene. Through the innovative quaternary conductive agent combination and low-temperature plasma synergistic modification technology, the conductivity and binding force of a prime coat coating are remarkably improved, and meanwhile the pulping process and the aluminum foil pretreatment effect are optimized. The flake graphite is used as a micron-sized conductive agent, a main body frame of the conductive layer is built, the surface roughness is increased, and a good foundation is provided for subsequent attachment of the positive electrode active layer; gaps among the flake graphite are filled with the spherical carbon black, and a basic conductive network is constructed.

Description

Technical Field

[0001] The present invention relates to the technical field of materials for lithium batteries, and in particular to a primer slurry for a lithium battery positive electrode and a method for preparing a primer coating. Background Art

[0002] Lithium-ion battery positive electrodes are typically produced by mixing active materials with a conductive agent, binder, and solvent, coating the mixture onto an aluminum foil current collector, and then drying it. However, the low conductivity of lithium iron phosphate (LFP) positive electrode materials, along with the residual grease and slippery properties of the aluminum foil surface, results in high contact resistance and insufficient bonding strength between the positive electrode active layer and the aluminum foil after coating, impacting the battery's charge, discharge, and cycling performance. The current industry solution involves pre-priming the aluminum foil current collector with a conductive coating to reduce interfacial resistance and improve bonding strength.

[0003] In existing water-based primer slurry systems, conductive agents often utilize a combination of carbon black, graphite, carbon nanotubes, or graphene. However, due to their tendency to agglomerate and their low polarity and lipophilicity, these conductive agents are difficult to disperse in aqueous media, resulting in insufficient primer uniformity and conductivity. Furthermore, residual rolling grease and low dyne value on the aluminum foil surface lead to poor wetting and spreading of the primer slurry, further compromising coating adhesion. While the industry has attempted to increase the dyne value of aluminum foil surfaces through corona treatment, the results have been limited. Summary of the Invention

[0004] In view of this, the present invention provides a primer slurry for a lithium battery positive electrode and a method for preparing a primer coating to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention discloses a lithium battery positive electrode primer slurry, which is prepared from the following components in percentage by mass:

[0007]

[0008]

[0009] The conductive agent consists of spherical conductive carbon black, flake conductive graphite, carbon nanotubes and graphene.

[0010] As a further solution of the present invention: the mass percentages of the spherical conductive carbon black, flaky conductive graphite, carbon nanotubes and graphene in the conductive agent are 45-55%, 20-30%, 20-25% and the remainder respectively, wherein the mass ratio of carbon nanotubes to graphene is 0.8-1.3.

[0011] As a further solution of the present invention: the carbon nanotubes are single-walled carbon nanotubes.

[0012] As a further solution of the present invention: the spherical conductive carbon black, carbon nanotubes, and graphene are all nano-scale particles, and the flaky conductive graphite is micron-scale particles.

[0013] As a further solution of the present invention: the conductive agent is preliminarily subjected to plasma modification treatment.

[0014] Furthermore, the plasma treatment parameters of the four components of the conductive agent are as follows:

[0015] Spherical conductive carbon black: baking temperature 90-100℃, baking time 8-10min, radio frequency plasma treatment equipment, vacuum degree 10-1-10-2Pa, plasma treatment gas is a mixture of oxygen and argon (volume ratio of 1:2-1:2.5), plasma treatment power 85-95W, time 2-3min;

[0016] Flake conductive graphite: baking temperature 90-100℃, baking time 8-10min, RF plasma treatment equipment, vacuum degree 10-1-10-2Pa, plasma treatment gas is nitrogen, plasma treatment power 75-85W, time 4-6min;

[0017] Carbon nanotube powder CNTs: baking temperature 80-90℃, baking time 6-8min, radio frequency plasma treatment equipment, 10-1-10-2Pa, plasma treatment gas is ammonia, plasma treatment power 70-80W, baking time 2-4min;

[0018] Graphene powder: baking temperature 80-90℃, baking time 8-13-5min, pulse plasma treatment equipment, vacuum degree 10-1-10-2Pa, plasma treatment gas is ammonia, plasma treatment power 60-80W, pulse frequency 5-8kHz, time 1-3min;

[0019] As a further solution of the present invention: the plasma modification treatment gas is one or a combination of oxygen, argon, nitrogen or ammonia, with a power of 50-500W and a temperature of 20-80°C.

[0020] As a further solution of the present invention: its solid content is 9-12%.

[0021] As a further embodiment of the present invention: the adhesive is a polyacrylate water-based adhesive; and / or,

[0022] The alcohol solvent is n-propanol, isopropanol or n-butanol.

[0023] In a second aspect, the present invention discloses a method for preparing the above-mentioned lithium battery positive electrode primer slurry, such as Figure 2 As shown, the following steps are included:

[0024] The conductive agent and the adhesive are fully mixed under an inert gas atmosphere to obtain a mixed powder;

[0025] Add the mixed powder into a portion of deionized water for premixing and dispersion to obtain a mixed slurry;

[0026] Another portion of the premixed liquid formed by mixing deionized water and alcohol solvent is added to the mixed slurry in multiple times, and after mixing evenly, the mixture is ground and sieved to obtain the primer slurry.

[0027] As a further solution of the present invention: comprising the following steps:

[0028] The surface of the aluminum foil is treated with plasma cleaning technology to make the dyne value of the aluminum foil surface 60-65dyn / cm;

[0029] The primer slurry is applied to the cleaned aluminum foil surface by micro-concave roller coating or ultrasonic spraying, and after drying, a positive electrode primer coating with a thickness of 0.8-1.2 μm is obtained;

[0030] Wherein, the primer slurry is the lithium battery positive electrode primer slurry according to any one of claims 1 to 6.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention significantly improves the conductivity and bonding strength of the primer coating through an innovative combination of quaternary conductive agents and low-temperature plasma synergistic modification technology, while optimizing the pulping process and aluminum foil pretreatment effects. As a micron-sized conductive agent, flake graphite builds the main framework of the conductive layer and increases the surface roughness, providing a good foundation for the subsequent adhesion of the positive active layer; spherical carbon black fills the gaps between the flake graphite and constructs a basic conductive network. However, the conductive network formed by the traditional combination of flake graphite and spherical carbon black is still mainly point contact, with tiny gaps, resulting in high impedance. To this end, the present invention introduces linear carbon nanotubes and planar graphene. Carbon nanotubes can provide linear contact channels and are dispersed in tiny gaps, while graphene provides surface contact channels for tiny gaps, forming a complete point-line-surface conductive channel, thereby significantly reducing the impedance of the primer coating, and the film resistance can be as low as 0.6-0.8mΩ.

[0033] Furthermore, through moderately low-temperature plasma treatment technology under a specific atmosphere, the surface of the quaternary conductive agent is modified. Polar groups (such as -COOH and -OH) are introduced to the surface without affecting the conductive properties of the conductive material, improving hydrophilicity and increasing the specific surface area. This modification not only avoids the structural destruction of chain-like conductive materials (such as carbon nanotubes and graphene) caused by the high-speed shearing required due to the difficulty of dispersing the conductive agent in aqueous solvents, but also achieves uniform dispersion of the conductive agent in the aqueous solvent, resulting in a highly dispersible slurry without the addition of a dispersant, providing guarantees for subsequent pulping and the integrity of the conductive network.

[0034] In terms of aluminum foil pretreatment, this invention utilizes plasma cleaning technology to increase the dyne value of the aluminum foil surface to 60-65 dyn / cm, thoroughly removing residual oil stains on the surface and ensuring good wetting and spreading of the primer slurry on the aluminum foil surface. Combined with an optimized coating process, the primer coating achieves a bonding strength of 500-600 N / m and a surface density uniformity of ±0.03 g / ㎡, significantly improving the stability and mechanical properties of the battery cell interface.

[0035] Through the above innovations, the present invention not only solves the problems of poor dispersion of primer slurry, high coating impedance and insufficient bonding strength in the prior art, but also simplifies the preparation process and reduces production costs, providing comprehensive technical support for the preparation of high-performance lithium-ion battery positive electrode sheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 1 is the coating surface density uniformity curve of the embodiment and the comparative example;

[0037] Figure 2 This is a flow chart for preparing the slurry of the present invention. DETAILED DESCRIPTION

[0038] To facilitate understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0040] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0041] Spherical conductive carbon black, purchased from Timcal, Switzerland, brand: Super PTM Li;

[0042] Flake conductive graphite, purchased from Timcal, Switzerland, brand KS-6;

[0043] Carbon nanotubes, brand OCSiAl, grade TUBALL TM ;

[0044] Graphene was purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences, with the brand name TNWIGNP;

[0045] Adhesive: PAA adhesive is selected;

[0046] Alcohol solvent, isopropyl alcohol is selected;

[0047] All materials are commercially available common products.

[0048] It is understood that the above raw materials and reagents are only examples of some specific embodiments of the present invention, which make the technical solution of the present invention clearer, and do not mean that the present invention can only adopt the above reagents. The specific scope in the claims shall prevail. In addition, the "parts" described in the examples and comparative examples, unless otherwise specified, refer to parts by weight.

[0049] Any range described in the present invention includes the end value and any numerical value between the end values and any sub-range formed by the end value or any numerical value between the end values.

[0050] Conductive agent pretreatment: Spherical conductive carbon black (Super P), flake conductive graphite (SFG), single-walled carbon nanotube powder (CNTs), and graphene are dried and then placed in radio frequency or pulse plasma treatment equipment for low-temperature plasma treatment, and vacuumed to 10 -1 -10 -2 Pa, introduce specific gas, adjust the power and treatment time of the plasma treatment equipment, and place the treated powder in a drying oven for standby use; specific parameters are shown in Table 1.

[0051] Table 1

[0052]

[0053] Example 1

[0054] Weigh 25 parts of spherical conductive carbon black, 12 parts of flake conductive graphite, 10 parts of single-walled carbon nanotube powder, 1 part of graphene, and 50 parts of PAA adhesive powder, place them in a drum ball mill and dry-mix them under a nitrogen atmosphere at a speed of 85 rpm, using nitrogen as the protective gas for milling, and mill for 1.3 h to obtain a premixed dry powder combination;

[0055] Weigh 250 parts of deionized water, add the premixed dry powder combination to the deionized water, and use a double planetary mixer to stir at low speed for preliminary wetting and dispersion. After the dry powder is added, continue stirring for 18 minutes at a low-speed stirring speed of 14 rpm and a rotation speed of 490 rpm to obtain transition slurry 1;

[0056] 500 parts of deionized water and alcohol solvent were premixed to obtain a premixed solution;

[0057] The premix was added to the transition slurry 1 in steps. In the first step, 50 wt.% of the premix was added and then dispersed in a double planetary mixer at a medium speed with an orbital speed of 14 rpm, a rotation speed of 680 rpm, and a time of 16 minutes. In the second step, the remaining premix was added and the double planetary mixer was used to disperse the mixture at a medium speed for 18 minutes. Finally, an ultrasonic disperser was used to disperse the mixture for 26 minutes with an ultrasonic dispersion power of 380 W and an ultrasonic frequency of 60 kHz to obtain a transition slurry 2.

[0058] The mixed primer slurry was ground and sieved for 0.8 h to obtain a finished primer slurry.

[0059] Example 2

[0060] Weigh 23 parts of spherical conductive carbon black, 14 parts of flake conductive graphite, 11 parts of single-walled carbon nanotube powder, 1 part of graphene, and 55 parts of adhesive dry powder, place them in a drum ball mill and dry-mix them under a nitrogen atmosphere at a speed of 85 rpm, with nitrogen as the protective gas for milling, and for 1.3 h to obtain a premixed dry powder combination;

[0061] Weigh 260 parts of deionized water, add the premixed dry powder combination to the deionized water, and use a double planetary mixer to stir at low speed for preliminary wetting and dispersion. After the dry powder is added, continue stirring for 18 minutes at a low speed stirring speed of 14 rpm and a rotation speed of 490 rpm to obtain transition slurry 1;

[0062] 500 parts of deionized water and alcohol solvent were premixed to obtain a premixed solution;

[0063] The premix was added to the transition slurry 1 in steps. In the first step, 50 wt.% of the premix was added and then dispersed in a double planetary mixer at a medium speed with an orbital speed of 14 rpm, a rotation speed of 680 rpm, and a time of 16 minutes. In the second step, the remaining premix was added and the double planetary mixer was used to disperse the mixture at a medium speed for 18 minutes. Finally, an ultrasonic disperser was used to disperse the mixture for 26 minutes with an ultrasonic dispersion power of 380 W and an ultrasonic frequency of 60 kHz to obtain a transition slurry 2.

[0064] The mixed primer slurry was ground and sieved for 0.8 h to obtain a finished primer slurry.

[0065] Example 3

[0066] Weigh 24 parts of spherical conductive carbon black, 13 parts of flake conductive graphite, 10 parts of single-walled carbon nanotube powder, 1 part of graphene, and 50 parts of adhesive dry powder, place them in a drum ball mill and dry-mix them under a nitrogen atmosphere at a speed of 85 rpm, with nitrogen as the protective gas for milling, and for 1.3 h to obtain a premixed dry powder combination;

[0067] Weigh 240 parts of deionized water, add the premixed dry powder combination to the deionized water, and use a double planetary mixer to stir at low speed for preliminary wetting and dispersion. After the dry powder is added, continue stirring for 18 minutes at a low-speed stirring speed of 14 rpm and a rotation speed of 490 rpm to obtain transition slurry 1;

[0068] 500 parts of deionized water and alcohol solvent were premixed to obtain a premixed solution;

[0069] The premix was added to the transition slurry 1 in steps. In the first step, 50 wt.% of the premix was added and then dispersed in a double planetary mixer at a medium speed with an orbital speed of 14 rpm, a rotation speed of 680 rpm, and a time of 16 minutes. In the second step, the remaining premix was added and the double planetary mixer was used to disperse the mixture at a medium speed for 18 minutes. Finally, an ultrasonic disperser was used to disperse the mixture for 26 minutes with an ultrasonic dispersion power of 380 W and an ultrasonic frequency of 60 kHz to obtain a transition slurry 2.

[0070] The mixed primer slurry was ground and sieved for 0.8 h to obtain a finished primer slurry.

[0071] Comparative Example 1

[0072] Take 250 parts of a PAA binder solution with a solid content of 20-25%, take 40 parts of conductive carbon black, and 20 parts of conductive graphite, add the conductive carbon black and conductive graphite to the binder solution, and stir at a low speed using a double planetary mixer at a revolution speed of 8-12 rpm and a rotation speed of 450-550 rpm for 10-15 minutes to obtain a transition slurry 1 of the conductive agent and the solution;

[0073] 245 parts of deionized water were added to the conductive agent and binder mixture 1, and stirred at high speed using a double planetary mixer at an orbital speed of 8-12 rpm and a rotation speed of 900-1100 rpm for 25-35 minutes to obtain a transition slurry 2.

[0074] Take 150 parts of alcohol solvent and 245 parts of deionized water, and premix the alcohol solvent and deionized water to obtain a premixed solution;

[0075] Add the premix of alcohol and water to transition slurry 2, and stir at ultra-high speed using a planetary mixer at an orbital speed of 13-18 rpm, a rotational speed of 1400-1600 rpm, and a stirring time of 60-70 min to obtain transition slurry 3;

[0076] Grind and filter the transition slurry 3 for 2-3 hours to obtain the finished primer slurry.

[0077] Comparative Example 2

[0078] Take 250 parts of a PAA binder glue with a solid content of 20-25%, take 30 parts of conductive carbon black, 15 parts of conductive graphite, 10 parts of carbon nanotube powder, and 5 parts of graphene powder, add the four conductive agents to the binder glue, and stir at low speed using a double planetary mixer at an orbital speed of 8-12 rpm and a rotation speed of 450-550 rpm for 10-15 minutes to obtain a transition slurry 1 of the conductive agent and the glue;

[0079] 245 parts of deionized water were added to the conductive agent and binder mixture 1, and stirred at high speed using a double planetary mixer at an orbital speed of 8-12 rpm and a rotation speed of 900-1100 rpm for 25-35 minutes to obtain a transition slurry 2.

[0080] Take 150 parts of alcohol solvent and 245 parts of deionized water, and premix the alcohol solvent and deionized water to obtain a premixed solution;

[0081] Add the premix of alcohol and water to transition slurry 2, and stir at ultra-high speed using a planetary mixer at an orbital speed of 13-18 rpm, a rotational speed of 1400-1600 rpm, and a stirring time of 60-70 min to obtain transition slurry 3;

[0082] The transition slurry 3 is ground and sieved for 2-3 hours to obtain a finished primer slurry.

[0083] Comparative Example 3

[0084] Weigh 25 parts of spherical conductive carbon black, 12 parts of flake conductive graphite, 10 parts of single-walled carbon nanotube powder, 2 parts of graphene, and 50 parts of adhesive dry powder, place them in a drum ball mill and dry-mix them under an inert gas atmosphere at a speed of 85 rpm, nitrogen as the ball milling protective gas, and ball milling for 1.3 h to obtain a premixed dry powder combination;

[0085] Weigh 250 parts of deionized water, add the premixed dry powder combination to the deionized water, and use a double planetary mixer to stir at low speed for preliminary wetting and dispersion. After the dry powder is added, continue stirring for 18 minutes at a low-speed stirring speed of 14 rpm and a rotation speed of 490 rpm to obtain transition slurry 1;

[0086] 500 parts of deionized water and alcohol solvent were premixed to obtain a premixed solution;

[0087] The premix was added to the transition slurry 1 in steps. In the first step, 50 wt.% of the premix was added and then dispersed in a double planetary mixer at a medium speed with an orbital speed of 14 rpm, a rotation speed of 680 rpm, and a time of 16 minutes. In the second step, the remaining premix was added and the double planetary mixer was used to disperse the mixture at a medium speed for 18 minutes. Finally, an ultrasonic disperser was used to disperse the mixture for 26 minutes with an ultrasonic dispersion power of 380 W and an ultrasonic frequency of 60 kHz to obtain a transition slurry 2.

[0088] The mixed primer slurry was ground and sieved for 0.8 h to obtain a finished primer slurry.

[0089] Comparative Example 4

[0090] Weigh 25 parts of spherical conductive carbon black, 12 parts of flaky conductive graphite, 14 parts of single-walled carbon nanotube powder, and 1 part of graphene) and 50 parts of adhesive dry powder, place them in a drum ball mill and dry-mix them under an inert gas atmosphere at a speed of 85 rpm, with nitrogen as the ball milling protective gas, for 1.3 h to obtain a premixed dry powder combination;

[0091] Weigh 150 parts of deionized water, add the premixed dry powder combination to the deionized water, and use a double planetary mixer to stir at low speed for preliminary wetting and dispersion. After the dry powder is added, continue stirring for 18 minutes at a low-speed stirring speed of 14 rpm and a rotation speed of 490 rpm to obtain transition slurry 1;

[0092] 500 parts of deionized water and alcohol solvent were premixed to obtain a premixed solution;

[0093] The premix was added to the transition slurry 1 in steps. In the first step, 50 wt.% of the premix was added and then dispersed in a double planetary mixer at a medium speed with an orbital speed of 14 rpm, a rotation speed of 680 rpm, and a time of 16 minutes. In the second step, the remaining premix was added and the double planetary mixer was used to disperse the mixture at a medium speed for 18 minutes. Finally, an ultrasonic disperser was used to disperse the mixture for 26 minutes with an ultrasonic dispersion power of 380 W and an ultrasonic frequency of 60 kHz to obtain a transition slurry 2.

[0094] The mixed primer slurry was ground and sieved for 0.8 h to obtain a finished primer slurry.

[0095] Test Case

[0096] Aluminum foil for alloy lithium batteries was selected, model 1100, with a thickness of 12-13 μm. A plasma cleaning machine was used to perform plasma cleaning on both sides of the aluminum foils of Example 1, Example 2, Comparative Example 3, and Comparative Example 4, and the cleaning was performed three times. The plasma generating power was 650 W, the plasma generating gas was nitrogen, and the gas pressure was 0.14 MPa. A corona machine was used to clean both sides of the aluminum foils of Comparative Example 1 and Comparative Example 2 three times and the foils were set aside. The corona power was 7 kW. The primer slurries obtained in the examples and comparative examples were respectively coated on the cleaned aluminum foil surfaces by a micro-concave coating method, with a coating thickness of 1±0.2 μm. The primed aluminum foil was dried to obtain a finished primer sample. The baking temperature was 90° C. and the time was 4 min.

[0097] The particle size of the finished primer slurries of the Examples and Comparative Examples was measured using a laser particle size analyzer. The surface density, sheet resistance, and cohesion of the finished primer samples were measured using a halogen analyzer, a microbalance, a sheet resistance meter, and a microtensile testing machine. The test results are shown in Tables 3-5. The surface density test points were selected as follows: ten equally spaced locations across the width of the aluminum foil after primer coating.

[0098] Table 3 Test results of primer slurry particle size

[0099]

[0100]

[0101] Table 4 Surface density test results of each test point of the coating

[0102]

[0103] Based on the data in Table 4, the coating surface density uniformity curve is drawn. Figure 1 .

[0104] Table 5 Test results of film resistance and coating cohesion of coating

[0105]

[0106]

[0107] According to Table 3-5 and Figure 1The results were analyzed: the primer slurry obtained by combining plasma modification with dry powder premixing in this case has narrow particle size, good particle size consistency, and good slurry dispersion uniformity; the primer coating surface density obtained by implementation is better than that obtained by the conventional implementation path comparison example, and the embodiment can reach ±0.03g / m 2 , while the comparative examples 1 and 2 are ±0.12g / m 2 ; The impedance of the primer coating obtained by implementation is very low, and the diaphragm resistance of the embodiment can reach 0.6-0.8mΩ, which is significantly lower than that of the comparative example; the cohesive force between the primer coating surface and the aluminum foil obtained by implementation is higher, and the cohesive force of the embodiment can reach 580-600N / m, which is significantly higher than that of comparative example 1 and comparative example 2; comparative example 3 and comparative example 4 are the application of the technical route of this case, but the mass ratio of carbon nanotubes / graphene is lower and higher than the ratio of this case. Although comparative examples 3 and comparative examples 4 are similar to the embodiment in terms of particle size, surface density uniformity and cohesive force, the diaphragm resistance is higher than that of the embodiment.

[0108] Although this specification is described according to implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0109] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent modifications made according to the scope of the claims of the present application are within the scope of protection of the claims of the present application.

Claims

1. A lithium battery positive electrode primer slurry, characterized in that: It is prepared from the following components in percentage by mass: The conductive agent consists of spherical conductive carbon black, flake conductive graphite, carbon nanotubes and graphene.

2. The lithium battery positive electrode primer slurry according to claim 1, characterized in that The mass percentages of the spherical conductive carbon black, flaky conductive graphite, carbon nanotubes and graphene in the conductive agent are 45-55%, 20-30%, 20-25% and the remainder respectively, wherein the mass ratio of carbon nanotubes to graphene is 0.8-1.

3.

3. The lithium battery positive electrode primer slurry according to claim 1, characterized in that The carbon nanotubes are single-walled carbon nanotubes.

4. The lithium battery positive electrode primer slurry according to claim 1, characterized in that The spherical conductive carbon black, carbon nanotubes and graphene are all nano-scale particles, and the flaky conductive graphite is micron-scale particles.

5. The lithium battery positive electrode primer slurry according to claim 1, characterized in that: The conductive agent is preliminarily subjected to plasma modification treatment.

6. The lithium battery positive electrode primer slurry according to claim 1, characterized in that: The plasma modification treatment gas is one or a combination of oxygen, argon, nitrogen or ammonia, with a power of 50-500W and a temperature of 20-80°C.

7. The lithium battery positive electrode primer slurry according to claim 1, characterized in that: Its solid content is 9-12%.

8. The lithium battery positive electrode primer slurry according to claim 1, characterized in that: The adhesive is a polyacrylate water-based adhesive; and / or, The alcohol solvent is n-propanol, isopropanol or n-butanol.

9. The method for preparing the positive electrode primer slurry for lithium batteries according to any one of claims 1 to 8, wherein: The following steps are involved: The conductive agent and the adhesive are fully mixed under an inert gas atmosphere to obtain a mixed powder; Add the mixed powder into a portion of deionized water for premixing and dispersion to obtain a mixed slurry; Another portion of the premixed liquid formed by mixing deionized water and alcohol solvent is added to the mixed slurry in multiple times, and after mixing evenly, the mixture is ground and sieved to obtain the primer slurry.

10. A method for preparing a lithium battery positive electrode primer coating, characterized in that: The following steps are involved: The surface of the aluminum foil is treated with plasma cleaning technology to make the dyne value of the aluminum foil surface 60-65dyn / cm; The primer slurry is applied to the cleaned aluminum foil surface by micro-concave roller coating or ultrasonic spraying, and after drying, a positive electrode primer coating with a thickness of 0.8-1.2 μm is obtained; Wherein, the primer slurry is the lithium battery positive electrode primer slurry according to any one of claims 1 to 6.

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