Water-based conductive adhesive for lithium ion battery, preparation method of water-based conductive adhesive, positive plate and lithium ion battery

Abstract

The invention provides a water-based conductive adhesive for a lithium ion battery, a preparation method of the water-based conductive adhesive, a positive plate and the lithium ion battery. The preparation method of the aqueous conductive adhesive for the lithium ion battery provided by the invention comprises the following steps: A) mixing carboxyl carbon nanotubes with ethanol and water, and carrying out crushing treatment to obtain a dispersion liquid; carrying out centrifugal treatment on the dispersion liquid, and drying the obtained solid to obtain a pretreated carbon nanotube; and B) mixing the pretreated carbon nanotubes with acrylic acid, an initiator and an accelerant, and heating for polymerization reaction in a protective atmosphere to obtain the water-based conductive adhesive. The aqueous conductive adhesive for the lithium ion battery prepared by the invention can effectively reduce the internal resistance of the battery, improve the discharge rate and the median voltage of the battery and integrally improve the performance of the battery.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery materials, and in particular to a lithium ion battery aqueous conductive adhesive and a preparation method thereof, a positive electrode sheet and a lithium ion battery. Background Art

[0002] Lithium-ion battery is a secondary battery (rechargeable battery) that mainly relies on the movement of lithium ions between the positive and negative electrodes to work. + Insertion and deinsertion back and forth between the two electrodes; specifically, during charging, Li + It is deintercalated from the positive electrode and intercalated into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state. The opposite is true during discharge.

[0003] The current market's wound-structure lithium-ion batteries generally have problems such as high internal resistance, poor rate performance, and low median voltage. As people's demand for the performance of lithium-ion battery products increases, the current battery performance can no longer meet market demand. Summary of the invention

[0004] In view of this, the present invention provides a lithium ion battery water-based conductive adhesive and a preparation method thereof, a positive electrode sheet and a lithium ion battery. The lithium ion battery water-based conductive adhesive prepared by the present invention can effectively reduce the internal resistance of the battery, increase the battery discharge rate and median voltage, and improve the overall battery performance.

[0005] The present invention provides a method for preparing a water-based conductive adhesive for lithium ion batteries, comprising the following steps:

[0006] A) mixing carboxyl carbon nanotubes with ethanol and water, and crushing them to obtain a dispersion; centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes;

[0007] B) mixing the pretreated carbon nanotubes with acrylic acid, an initiator and a promoter, and heating them under a protective atmosphere to carry out polymerization reaction to obtain a water-based conductive adhesive.

[0008] Preferably, in step A), the volume ratio of ethanol to water is 1:(1-5);

[0009] The ratio of the carboxyl carbon nanotubes to the total amount of ethanol and water is 1 g: (10-50) mL.

[0010] Preferably, in step A), the volume ratio of ethanol to water is 1:3.

[0011] Preferably, in step B), the mass ratio of the pretreated carbon nanotubes to acrylic acid is 1:(0.5-2).

[0012] Preferably, in step B), the initiator is at least one of a BPO initiator and dibenzoyl peroxide;

[0013] The amount of the initiator is 0.5% to 5% of the mass of acrylic acid;

[0014] The accelerator is at least one of N,N-dimethylaniline and p-methylaniline;

[0015] The amount of the accelerator used is 0.1% to 1% of the mass of acrylic acid.

[0016] Preferably, in step B), the temperature for the heating polymerization reaction is 73-78° C. and the time is 6-10 hours.

[0017] The present invention also provides a water-based conductive adhesive for lithium ion batteries prepared by the preparation method described in the above technical solution.

[0018] The present invention also provides a positive electrode sheet, wherein the adhesive is the aqueous conductive adhesive for lithium ion batteries described in the above technical solution.

[0019] Preferably, it is prepared by the following preparation method:

[0020] S1, mixing active materials, conductive agents, binders and solvents to obtain positive electrode slurry;

[0021] S2, coating the positive electrode slurry on a current collector, drying, and slicing to obtain a positive electrode sheet;

[0022] Wherein, the adhesive is the aqueous conductive adhesive for lithium-ion batteries according to claim 8.

[0023] The present invention also provides a lithium-ion battery, characterized in that the positive electrode sheet therein is the positive electrode sheet described in the above technical solution.

[0024] The preparation method provided by the present invention comprises the following steps: firstly mixing carboxyl carbon nanotubes with ethanol and water, and performing crushing treatment to obtain a dispersion; then centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes; wherein the obtained pretreated carbon nanotubes have good dispersibility and surface activity, and can be better combined with polymerization monomers such as acrylic acid to form a uniform conductive network structure, thereby improving the conductive performance and bonding performance of the water-based conductive adhesive. Then, the pretreated carbon nanotubes are mixed with acrylic acid, an initiator and a promoter, and heated under a protective atmosphere to perform a polymerization reaction to obtain a water-based conductive adhesive; wherein the polymerization reaction is performed under the protection of an inert gas to prevent oxygen from interfering with the reaction, thereby ensuring the smooth progress of the polymerization reaction and the stable quality of the product; during the polymerization process, the pretreated carbon nanotubes, as a conductive filler, copolymerize with the acrylic acid monomer to form a uniform conductive network structure, and the addition of the initiator and promoter can effectively improve the efficiency of the polymerization reaction and the molecular weight of the product, thereby obtaining a water-based conductive adhesive with good conductive performance and bonding performance. The above products can form a strong conductive and elastic network, in which the continuous conductive skeleton can disperse and bond active nanoparticles through an efficient and strong "sheet-to-point" bonding mode. The negative and positive electrodes have excellent structural and interfacial stability and enhanced electronic conductivity, which is conducive to reducing the internal resistance of the battery, increasing the battery discharge rate and median voltage, and improving the overall battery performance.

[0025] The test results show that compared with conventional adhesives, the use of the aqueous conductive adhesive of the present invention can reduce the internal resistance of the battery by about 11 mΩ, increase the discharge rate by more than 3%, increase the median voltage by more than 81 mV at 1C, increase the median voltage by more than 149 mV at 3A, and increase the median voltage by more than 157 mV at 5A. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0027] Figure 1 This is the effect diagram of the battery internal resistance test;

[0028] Figure 2 This is a battery discharge rate test effect diagram; among them, Figure 2 (a) is a comparison chart at 3A magnification. Figure 2 (b) is a comparison chart at 5A magnification;

[0029] Figure 3 This is the battery median voltage test effect diagram. DETAILED DESCRIPTION

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0032] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] Herein, when it comes to numerical ranges, unless otherwise specified, the numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0034] In this article, when referring to the units of a data range, if only the right endpoint is followed by a unit, it means that the units of the left and right endpoints are the same.

[0035] The present invention provides a method for preparing a water-based conductive adhesive for lithium ion batteries, comprising the following steps:

[0036] A) mixing carboxyl carbon nanotubes with ethanol and water, and crushing them to obtain a dispersion; centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes;

[0037] B) mixing the pretreated carbon nanotubes with acrylic acid, an initiator and a promoter, and heating them under a protective atmosphere to carry out polymerization reaction to obtain a water-based conductive adhesive.

[0038] [About Step A]:

[0039] A) mixing carboxyl carbon nanotubes with ethanol and water, and crushing them to obtain a dispersion; centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes.

[0040] In the present invention, the source of the carboxyl carbon nanotubes is not particularly limited and can be any commercial product.

[0041] In the present invention, the water is preferably deionized water. The volume ratio of the ethanol to water is preferably 1:(1-5), specifically 1:1, 1:2, 1:3, 1:4, 1:5, and more preferably 1:3.

[0042] In the present invention, the mixing method is preferably: firstly, ethanol and water are mixed to obtain a mixed solution, and then the carboxyl carbon nanotubes are added to the mixed solution.

[0043] In the present invention, the ratio of the carboxyl carbon nanotubes to the total amount of ethanol and water is preferably 1 g: (10-50) mL.

[0044] In the present invention, after the above mixing, the obtained mixture is subjected to a crushing treatment, specifically, the crushing treatment is carried out by an ultrasonic crusher. In the present invention, the crushing treatment conditions are preferably as follows: power 200W, time 30min. After the above crushing treatment, a dispersion is obtained.

[0045] In the present invention, after obtaining the dispersion, centrifugal treatment is performed, specifically using a centrifuge to obtain a solid. Then, the obtained solid is dried. The drying temperature is preferably 50° C. and the drying time is preferably 12 hours. After drying, pretreated carbon nanotubes are obtained.

[0046] [About step B]:

[0047] B) mixing the pretreated carbon nanotubes with acrylic acid, an initiator and a promoter, and heating them under a protective atmosphere to carry out polymerization reaction to obtain a water-based conductive adhesive.

[0048] In the present invention, acrylic acid is a polymerizable monomer. The mass ratio of the pretreated carbon nanotubes to acrylic acid is preferably 1:(0.5-2), specifically 1:0.5, 1:1, 1:1.5, 1:2, and more preferably 1:1.

[0049] In the present invention, the initiator is preferably at least one of BPO initiator and dibenzoyl peroxide, more preferably BPO initiator. In the present invention, the amount of the initiator is preferably 0.5% to 5% of the mass of acrylic acid, specifically 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0050] In the present invention, the accelerator is preferably at least one of N,N-dimethylaniline and p-methylaniline, more preferably N,N-dimethylaniline. In the present invention, the amount of the accelerator is preferably 0.1% to 1% by mass of acrylic acid, specifically 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%.

[0051] In the present invention, the order of mixing is preferably: firstly, acrylic acid, initiator and promoter are mixed to obtain a mixture; then, the pretreated carbon nanotubes obtained in step A) are added to the mixture for mixing. In the present invention, the mixing method is not particularly limited, and the materials can be mixed uniformly by conventional mixing methods in the art, such as stirring.

[0052] In the present invention, after the materials are mixed, they are heated under a protective atmosphere for polymerization reaction. There is no special restriction on the type of atmosphere of the protective atmosphere, and it can be a conventional protective gas in the art, such as nitrogen, argon, etc., preferably a nitrogen atmosphere. In the present invention, the temperature of the heating polymerization reaction is preferably 73-78°C, specifically 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, and more preferably 75°C; the time of the polymerization reaction is preferably 6-10h, specifically 6h, 7h, 8h, 9h, 10h, and more preferably 8h. After the polymerization reaction, a crude product is obtained. The present invention preferably also performs post-treatment; the post-treatment preferably includes: filtration and drying. After the crude product is filtered, the obtained solid is dried. The drying is preferably vacuum drying. The drying temperature is preferably 30-50°C, and more preferably 40°C; the drying time is preferably 22-26h, and more preferably 24h. After drying, a water-based conductive adhesive is obtained.

[0053] The preparation method provided by the present invention comprises the following steps: firstly mixing carboxyl carbon nanotubes with ethanol and water, and performing crushing treatment to obtain a dispersion; then centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes; wherein the obtained pretreated carbon nanotubes have good dispersibility and surface activity, and can be better combined with polymerization monomers such as acrylic acid to form a uniform conductive network structure, thereby improving the conductive performance and bonding performance of the water-based conductive adhesive. Then, the pretreated carbon nanotubes are mixed with acrylic acid, an initiator and a promoter, and heated under a protective atmosphere to perform a polymerization reaction to obtain a water-based conductive adhesive; wherein the polymerization reaction is performed under the protection of an inert gas to prevent oxygen from interfering with the reaction, thereby ensuring the smooth progress of the polymerization reaction and the stable quality of the product; during the polymerization process, the pretreated carbon nanotubes, as a conductive filler, copolymerize with the acrylic acid monomer to form a uniform conductive network structure, and the addition of the initiator and promoter can effectively improve the efficiency of the polymerization reaction and the molecular weight of the product, thereby obtaining a water-based conductive adhesive with good conductive performance and bonding performance. The above products can form a strong conductive and elastic network, in which the continuous conductive skeleton can disperse and bond active nanoparticles through an efficient and strong "sheet-to-point" bonding mode. The negative and positive electrodes have excellent structural and interfacial stability and enhanced electronic conductivity, which is conducive to reducing the internal resistance of the battery, increasing the battery discharge rate and median voltage, and improving the overall battery performance.

[0054] The present invention also provides a water-based conductive adhesive for lithium ion batteries prepared by the preparation method described in the above technical solution.

[0055] The present invention also provides an aqueous conductive slurry, comprising: an active material, a conductive agent, an adhesive and a solvent. Among them, the active material is preferably graphene. The conductive agent is preferably conductive carbon black. The adhesive is the aqueous conductive adhesive for lithium-ion batteries described in the above technical solution. The solvent is preferably water, more preferably deionized water. The dosage relationship of the adhesive, active material and conductive agent can be implemented according to the conventional dosage ratio in the conductive slurry in this field; in some embodiments of the present invention, the mass ratio of the adhesive, active material and conductive agent is 90:5:5. There is no special restriction on the dosage of the solvent, and an appropriate amount of solvent can be added according to the conventional dosage in this field to adjust the slurry.

[0056] Lithium-ion batteries mainly include: positive electrode, negative electrode, separator and electrolyte. Among them, the positive electrode is prepared by the following method: positive electrode active material, conductive agent, binder and solvent are mixed to prepare positive electrode slurry; positive electrode slurry is coated on the current collector, dried and sliced ​​to obtain positive electrode sheet.

[0057] The present invention also provides a positive electrode sheet, wherein the adhesive is the aqueous conductive adhesive for lithium ion batteries described in the above technical solution.

[0058] The present invention also provides a positive electrode sheet, which is preferably prepared by the following method:

[0059] S1, mixing active materials, conductive agents, binders and solvents to obtain positive electrode slurry;

[0060] S2, coating the positive electrode slurry on a current collector, drying, and slicing to obtain a positive electrode sheet;

[0061] Wherein, the adhesive is the aqueous conductive adhesive for lithium-ion batteries described in the above technical solution.

[0062] Regarding step S1: the active material is preferably graphene. The conductive agent is preferably conductive carbon black. The adhesive is the aqueous conductive adhesive for lithium-ion batteries described in the above technical solution. The solvent is preferably water, more preferably deionized water. The dosage of the adhesive, active material and conductive agent can be carried out according to the conventional dosage ratio in the conductive slurry in this field; in some embodiments of the present invention, the mass ratio of the adhesive, active material and conductive agent is 90:5:5. There is no special restriction on the dosage of the solvent, and an appropriate amount of solvent can be added according to the conventional dosage in this field to adjust the slurry.

[0063] Regarding step S2: There is no special restriction on the type of the current collector, which can be a conventional positive electrode current collector in the field, such as aluminum foil. After the positive electrode slurry is evenly coated on the current collector, it is dried. The drying is preferably vacuum drying. The drying temperature is preferably 95-105°C, more preferably 100°C; the drying time is preferably 22-26h, more preferably 24h. After drying, take it out after cooling, and use a slicer to cut it into positive electrode discs.

[0064] The present invention also provides a lithium ion battery, wherein the positive electrode sheet is the positive electrode sheet described in the above technical solution.

[0065] In the present invention, the negative electrode sheet of the lithium ion battery is preferably a lithium sheet. In the present invention, the electrolyte of the lithium ion battery is preferably a LiPF6 electrolyte. In the present invention, the diaphragm of the lithium ion battery is preferably a polypropylene diaphragm, more preferably a microporous polypropylene diaphragm, and in some embodiments, a Celgard2400 microporous polypropylene membrane.

[0066] The test results show that compared with conventional adhesives, the use of the aqueous conductive adhesive of the present invention can reduce the internal resistance of the battery by about 11 mΩ, increase the discharge rate by more than 3%, increase the median voltage by more than 81 mV at 1C, increase the median voltage by more than 149 mV at 3A, and increase the median voltage by more than 157 mV at 5A.

[0067] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0068] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available or can be prepared by known methods. The instruments are all conventionally selected in the art. Among them, the carboxyl carbon nanotubes are from Defang Nano.

[0069] Example 1

[0070] 1. Preparation of water-based conductive adhesive

[0071] A) 0.5 g of carboxyl carbon nanotubes were added to a mixture of ethanol and deionized water (volume of the mixture was 30 mL, wherein the volume ratio of ethanol to water was 1:3), and the mixture was crushed by an ultrasonic crusher (power 200 W, time 30 min) to obtain a dispersion. The dispersion was then centrifuged using a centrifuge, and the obtained solid was dried at 50° C. for 12 h to obtain pretreated carbon nanotubes.

[0072] B) acrylic acid, initiator BPO and accelerator N,N-dimethylaniline are put into a blender and stirred evenly (wherein the amount of initiator is 2% of the mass of acrylic acid, and the amount of accelerator is 0.5% of the mass of acrylic acid), transferred to a 250mL three-necked flask, and the pretreated carbon nanotubes obtained in step A) are added thereto (the mass ratio of the pretreated carbon nanotubes to acrylic acid is 1:1), and stirred evenly. Then, nitrogen is introduced for protection, and free radical polymerization is carried out at 75°C for reaction for 8 hours to obtain a crude adhesive product. Then, suction filtration is carried out, and the obtained solid is vacuum dried at 40°C for 24 hours to obtain an adhesive product.

[0073] 2. Assemble the battery

[0074] The above-mentioned adhesive product is mixed with graphene and conductive carbon black in a mass ratio of 90:5:5, and an appropriate amount of deionized water is added to prepare the slurry to obtain a positive electrode slurry. After that, the positive electrode slurry is evenly coated on the aluminum foil current collector and placed in a vacuum drying oven at 100°C for 24 hours. After drying and cooling, take it out and use a slicer to cut it into positive electrode discs with a diameter of 14 mm. After accurate weighing, transfer them to a glove box filled with high-purity argon for use. In the glove box, assemble the positive electrode material into a button battery, use a silicon-carbon composite material as the negative electrode, and use a 1M LiPF6 solution (solvent is V 碳酸乙烯酯 :V 碳酸甲乙酯 :V 碳酸二甲酯 =1:3:2), and the separator is Celgard2400 microporous polypropylene film. The assembly order is positive electrode shell, positive electrode sheet, separator, electrolyte, negative electrode sheet and negative electrode shell. After being packaged by a sealing machine, a CR2032 button battery is obtained. The assembled battery needs to be left at room temperature for 12 hours to allow the electrolyte to fully infiltrate the electrode sheet before the electrochemical performance test is carried out.

[0075] 3. Electrochemical performance test

[0076] The test objects are: the assembled battery of Example 1 and the battery of the control group. Among them, the battery of the control group is a conventional product, mainly using the traditional adhesive PVDF as an adhesive, and the rest is the same as Example 1.

[0077] (3.1) Internal resistance test

[0078] The internal resistance test was performed using a Solartron 1280Z electrochemical workstation with a frequency range of 100kHz-1mHz. The amplitude of the AC signal was set as 10Mv, and the data was collected and the Bode plot was drawn. The test results are shown in Figure 1 , Figure 1 It is a battery internal resistance test effect diagram. It can be seen that the internal resistance of the battery in Example 1 is 21mΩ, and the internal resistance of the battery in the control group is 32mΩ. The present invention can reduce the battery internal resistance by about 11mΩ.

[0079] (3.2) Discharge rate test

[0080] Use Solartron 1280Z electrochemical workstation to conduct discharge rate comparison test and pre-cycle activation battery. Conduct discharge test at different rates, 0.1C, 0.5C, 1C, 2C, 5C, etc., and record data. Test results refer to Figure 2 , Figure 2 This is the battery discharge rate test effect diagram, where: Figure 2 (a) is a comparison chart at 3A magnification. Figure 2 (b) is a comparison diagram at a rate of 5 A. It can be seen that compared with the control group, the discharge rate of the battery of the present invention is increased by more than 3%.

[0081] (3.3) Median voltage test

[0082] The Solartron 1280Z electrochemical workstation was used to perform the median voltage test. After pre-charging, the constant current and constant voltage mode was adopted, and the discharge was performed at 1C, 3A, 5A, etc., and the data was recorded. The test results are shown in Figure 3 , Figure 3 The figure is a test result of the median voltage of the battery. It can be seen that at 1C, the median voltage of the battery of the present invention is 81mV higher than that of the control group; at 3A, the median voltage of the battery of the present invention is 149mV higher than that of the control group; at 5A, the median voltage of the battery of the present invention is 157mV higher than that of the control group; under each rate condition, the median voltage of the battery of the present invention is significantly higher than that of the control group.

[0083] In summary, the present invention effectively reduces the internal resistance of the battery, increases the battery discharge rate and median voltage, and improves the overall comprehensive performance of the battery.

[0084] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for preparing a water-based conductive adhesive for lithium-ion batteries, characterized in that: The following steps are involved: A) mixing carboxyl carbon nanotubes with ethanol and water, and crushing them to obtain a dispersion; centrifuging the dispersion, and drying the obtained solid to obtain pretreated carbon nanotubes; B) mixing the pretreated carbon nanotubes with acrylic acid, an initiator and a promoter, and heating them under a protective atmosphere to carry out polymerization reaction to obtain a water-based conductive adhesive.

2. The preparation method according to claim 1, characterized in that: In step A), the volume ratio of ethanol to water is 1:(1-5); The ratio of the carboxyl carbon nanotubes to the total amount of ethanol and water is 1 g: (10-50) mL.

3. The preparation method according to claim 1 or 2, characterized in that: In step A), the volume ratio of ethanol to water is 1:

3.

4. The preparation method according to claim 1, characterized in that: In step B), the mass ratio of the pretreated carbon nanotubes to acrylic acid is 1:(0.5-2).

5. The preparation method according to claim 1, characterized in that: In step B), the initiator is at least one of a BPO initiator and dibenzoyl peroxide; The amount of the initiator is 0.5% to 5% of the mass of acrylic acid; The accelerator is at least one of N,N-dimethylaniline and p-methylaniline; The amount of the accelerator used is 0.1% to 1% of the mass of acrylic acid.

6. The preparation method according to claim 1, characterized in that: In step B), the temperature for the heating polymerization reaction is 73-78° C. and the time is 6-10 hours.

7. A water-based conductive adhesive for lithium-ion batteries prepared by the preparation method according to any one of claims 1 to 6.

8. A positive electrode sheet, characterized in that: The adhesive is the aqueous conductive adhesive for lithium ion batteries as described in claim 8.

9. The positive electrode sheet according to claim 8, characterized in that: Prepared by the following preparation method: S1, mixing active materials, conductive agents, binders and solvents to obtain positive electrode slurry; S2, coating the positive electrode slurry on a current collector, drying, and slicing to obtain a positive electrode sheet; Wherein, the adhesive is the aqueous conductive adhesive for lithium-ion batteries according to claim 8.

10. A lithium ion battery, characterized in that: The positive electrode sheet is the positive electrode sheet according to any one of claims 8 to 9.

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