An aqueous slurry suitable for coating the edges of a lithium battery negative electrode, and a preparation method and application thereof

Abstract

This application relates to the field of lithium battery adhesives, and more particularly to an aqueous slurry suitable for edge coating of lithium battery negative electrodes, its preparation method, and its application. The aqueous slurry for edge coating of lithium battery negative electrodes, by weight, comprises: 2-2.5 parts of aqueous acrylic resin adhesive and 97.5-98 parts of inorganic powder filler. Using the aqueous slurry provided in this application, the electrode coated with the aqueous slurry exhibits good flexibility and adhesion. Simultaneously, there is no interpenetration between the aqueous slurry and the negative electrode slurry, avoiding powder shedding due to poor adhesion. It also avoids internal short circuits in the battery caused by foil burrs, dust, and edge curling resulting from electrode edge cutting, significantly improving battery safety and yield.

Description

Technical Field

[0001] This application relates to the field of lithium battery adhesives, and more particularly to an aqueous slurry suitable for coating the edge of the negative electrode of a lithium battery, its preparation method and application. Background Technology

[0002] The Chinese lithium-ion battery market is growing steadily, and lithium-ion batteries will be widely used. Lithium-ion batteries can be specifically divided into positive electrode materials, negative electrode materials, electrolytes, separators, aluminum-plastic films, etc. Among them, positive and negative electrode materials are the decisive factors for their electrochemical performance, and the quality of the electrode edge has an important impact on the battery performance and quality, specifically including: (1) burrs and impurities, which can cause short circuits in the battery, leading to self-discharge or even thermal runaway; (2) thermal damage to materials, coating peeling, etc., which cause the materials to lose their activity and fail to function; (3) unevenness of the cut edge, which causes unevenness in the charging and discharging process of the electrode.

[0003] To eliminate electrode cutting defects, besides employing novel slitting technologies (such as laser slitting), burrs can also be flattened using a rolling method (as described in Chinese Patent CN101068045A). However, this process is relatively complex and the burrs are not completely eliminated. Applying insulating adhesive to the edges of lithium-ion battery electrodes (as described in Chinese Patent CN103236546A) can easily lead to residual bubbles, shrinkage, cracking, and curling. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides an aqueous slurry suitable for edge coating of lithium battery negative electrodes, its preparation method, and its application. Using the aqueous slurry provided in this application, the electrode coated with the slurry exhibits excellent flexibility and adhesion. Furthermore, there is no interpenetration between the aqueous slurry and the negative electrode slurry, avoiding powder shedding due to poor adhesion. It also prevents internal short circuits in the battery caused by foil burrs, dust, and edge curling resulting from electrode edge cutting, significantly improving battery safety and yield. The aqueous slurry prepared in this application for edge coating of lithium battery negative electrodes possesses excellent coating adhesion, flexibility, and coating appearance. Simultaneously, no interpenetration occurs when in contact with the negative electrode slurry, solving the problems of burrs and powder shedding that easily occur during the cutting process of negative electrode sheets.

[0005] In a first aspect, this application provides an aqueous slurry suitable for edge coating of lithium battery negative electrodes, employing the following technical solution:

[0006] A water-based slurry suitable for edge coating of lithium battery negative electrodes, comprising, by weight, 2-2.5 parts of water-based acrylic resin adhesive and 97.5-98 parts of inorganic powder filler, wherein the effective component of the water-based acrylic resin adhesive is water-based acrylic resin, and the structure of the water-based acrylic resin is shown in the following formula:

[0007]

[0008] In the formula, R1 is a straight-chain aliphatic hydrocarbon group composed of 2-10 methylene groups; R2 is a carboxyl group or an amide group; R3 is a functional monomer, which is at least one of acrylonitrile, vinyl acetate and styrene.

[0009] By adopting the above technical solution, the waterborne acrylic resin adhesive, as the main film-forming substance, provides the basic properties of the coating, such as adhesion, flexibility, and coating appearance. The straight-chain aliphatic hydrocarbon groups composed of methylene groups in the waterborne acrylic resin structure help increase the flexibility of the coating, while the functional monomers vinyl acetate and styrene help increase the adhesion of the coating. Inorganic powder fillers, as fillers that increase the volume of the coating, can improve the thickness and fullness of the coating. At the same time, the improved compatibility and dispersibility of the modified inorganic powder fillers with the waterborne acrylic resin adhesive reduce the shrinkage, cracking, and edge curling of the coating, and increase the bonding strength of the coating. In summary, the waterborne acrylic resin adhesive provides the basic properties of the coating, while the inorganic powder fillers, through modification, improve the compatibility and dispersibility of the coating, further optimizing the performance of the coating. The synergistic effect of the two results in the waterborne slurry coated on the edge of the lithium battery negative electrode having good performance, which can effectively solve the problems of burrs and powder shedding that easily occur during the cutting of the negative electrode sheet.

[0010] Preferably, the preparation method of the water-based acrylic resin adhesive includes the following steps:

[0011] S21, Base Component: According to the following mass percentages: add 5-10 parts of protective colloid to 1000-1500 parts of deionized water, heat to 80-90℃, stir at high speed for 20-30 minutes until the protective colloid is completely dissolved, then cool to 50-70℃; then add in sequence: 30-60 parts of acrylic monomer, 20-50 parts of water-soluble monomer, and 5-10 parts of functional monomer, stir and mix evenly, and heat to 70-85℃ to obtain component A;

[0012] S22. Polymerization reaction: Add 0.5-2 parts of initiator to 50 parts of deionized water and stir to mix evenly to obtain an initiator solution; add the initiator solution dropwise to component A, controlling the dropping rate, and complete the dropping over 2-3 hours. After the dropping is completed, raise the temperature to 85℃ and continue to keep it at that temperature for 2-3 hours. Then add 0.1-0.5 parts of initiator and keep it at that temperature for 1 hour. Then lower the temperature to stop the reaction. When the temperature drops below 40℃, discharge the material to obtain the water-based acrylic resin adhesive.

[0013] By adopting the above technical solution, in the preparation method of the waterborne acrylic resin adhesive, step S21 is the preparation of the base component, including adding the protective colloid to deionized water and heating and stirring until completely dissolved, then successively adding acrylic monomers, water-soluble monomers and functional monomers and mixing evenly to obtain component A. Step S22 is the polymerization reaction, adding the initiator to deionized water to prepare an initiator solution, then adding the initiator solution dropwise to component A, and controlling the reaction rate under specific conditions to complete the polymerization reaction and obtain the waterborne acrylic resin adhesive. The role of the waterborne acrylic resin adhesive in this application is mainly reflected in providing the basic properties of the coating, such as coating adhesion, flexibility and coating appearance. Its specific structure and the selection of functional monomers are beneficial to enhancing the performance of the coating. By using it in combination with inorganic powder fillers, the bonding strength of the coating can be improved and the occurrence of burrs and powdering during the cutting of the negative electrode sheet can be reduced. In the preparation process, the preparation of the base components in step S21 helps to establish suitable basic conditions for the polymerization reaction, while the polymerization reaction in step S22 enables the formation of the waterborne acrylic resin adhesive, ensuring the quality and performance of the final product. The synergistic effect of the waterborne acrylic resin adhesive and inorganic powder fillers further optimizes the coating formulation, improves the coating performance, and solves the problems in the edge coating process of lithium battery negative electrodes.

[0014] Preferably, the protective adhesive is one or a mixture of two of sodium polyacrylate, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol.

[0015] Preferably, the acrylic monomer is one or more selected from methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, isooctyl acrylate, methacrylic acid, methyl methacrylate, and ethyl methacrylate.

[0016] Preferably, the water-soluble monomer is one or more of acrylamide, hydroxymethylacrylamide, itaconic acid, hydroxypropyl acrylate, and carboxyethyl acrylate.

[0017] Preferably, the functional monomer is at least one of acrylonitrile, vinyl acetate, and styrene; and the initiator is one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0018] Preferably, the inorganic powder filler is at least one of boehmite and alumina.

[0019] Preferably, the inorganic powder filler is a modified inorganic powder filler, which is composed of boehmite and alumina in a mass ratio of 2:1 and is prepared by silane modification. The preparation method includes the following steps:

[0020] S81. According to the mass fraction, 1 part of γ-glycidoxypropyltrimethoxysilane is mixed with 100 parts of ethanol and 30 parts of water, and stirred evenly to obtain mixture A;

[0021] S82. Add 80 parts of boehmite and 40 parts of alumina to mixture A, then heat to 43°C, stir at 200 r / min for 90 min, and finally filter, wash, dry and grind at 75°C to obtain modified inorganic powder filler.

[0022] By adopting the above technical solution, inorganic powder fillers play an important role in the aqueous slurry coating of the negative electrode edge of lithium batteries. Modifying the inorganic powder fillers can improve their compatibility and dispersibility with aqueous acrylic resin adhesives, thereby improving the coating performance, reducing problems that occur during the coating process of lithium-ion battery negative electrode edges, such as coating shrinkage, cracking, and edge curling, increasing the coating's bonding strength, and reducing burrs and powder shedding during cutting. The modified inorganic powder filler of this application is composed of boehmite and alumina in a mass ratio of 2:1, and is prepared by modification with γ-glycidyl etheroxypropyltrimethoxysilane. Its preparation method includes two steps, S81 and S82: In step S81, γ-glycidyl etheroxypropyltrimethoxysilane is mixed with ethanol and water, and stirred evenly to obtain mixture A. In step S82, boehmite and alumina are added to mixture A, then heated and stirred for a certain time. Finally, the mixture is filtered, washed, dried, and ground to obtain the modified inorganic powder filler. The modified inorganic powder filler, through silane modification, achieves better compatibility and dispersibility with the waterborne acrylic resin adhesive, thereby enhancing the peel strength of the coating. The synergistic effect of the modified filler and the waterborne acrylic resin adhesive helps optimize the coating formulation, effectively improve coating performance, and reduce problems during the cutting process, thus providing a better solution for edge coating of lithium battery negative electrodes.

[0023] Secondly, this application provides a method for preparing an aqueous slurry suitable for edge coating of lithium battery negative electrodes, employing the following technical solution:

[0024] As a general technical concept, this application also provides a method for preparing the above-mentioned aqueous slurry suitable for edge coating of lithium battery negative electrode, including the following steps:

[0025] According to the mass fraction, water-based acrylic resin adhesive and inorganic powder filler are placed in a mixing tank and dispersed by high-speed stirring at 1000-2000 rpm for 1-2 hours to obtain a water-based slurry suitable for edge coating of lithium battery negative electrode.

[0026] Thirdly, this application provides an application of an aqueous slurry suitable for edge coating of lithium battery negative electrodes, employing the following technical solution:

[0027] As a general technical concept, this application also provides the above-mentioned aqueous slurry suitable for edge coating of lithium battery negative electrode as an edge coating slurry for lithium battery negative electrode sheet coated on the edge of the negative electrode sheet, characterized in that the lithium battery negative electrode sheet edge coating slurry is coated on the edge of the negative electrode sheet and dried and cured at a temperature of 80-130°C to obtain an insulating layer, wherein the edge coating layer has a thickness of 50-70 μm.

[0028] By adopting the above technical solution and using the aqueous slurry provided in this application for coating the edge of the negative electrode of a lithium battery, the electrode coated with the aqueous slurry can have good flexibility and adhesion. At the same time, the aqueous slurry and the negative electrode slurry do not interpenetrate, which can avoid the problem of powder falling off due to poor adhesion. It can also avoid the internal short circuit of the battery caused by foil burrs, dust, and edge flipping caused by cutting the electrode edge, which greatly improves battery safety and yield.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. Improve the flexibility and adhesion of coated electrodes: After coating with this water-based slurry, the electrodes have good flexibility and adhesion, and can be cut and folded without losing material; it helps to reduce the risk of coating peeling off the negative electrode due to vibration and other factors during use.

[0031] 2. Avoiding cross-penetration: The high molecular weight waterborne acrylic resin adhesive used in the aqueous slurry prepared in this application does not contain small molecule emulsifiers. The slurry has a large surface tension. Therefore, when it is coated simultaneously with the negative electrode slurry, it can effectively prevent cross-penetration between the two materials and maintain the normal operation of the battery.

[0032] 3. Improve battery safety and yield: By reducing the problem of powder shedding caused by poor adhesion and the problems of foil burrs, dust, and edge flipping caused by cutting the electrode edge, the occurrence of internal short circuits in the battery can be avoided, which greatly improves the safety of the battery and the yield of production. Moreover, it has good electrolyte resistance and the coating does not fall off after immersion in electrolyte for 72 hours.

[0033] 4. Improved coating performance and appearance: Water-based slurry has good coating adhesion and flexibility, and the coating appearance also meets the requirements, which helps to produce high-performance coatings and improve the overall quality of batteries.

[0034] 5. Reduce coating shrinkage, cracking, and curling: By using modified inorganic powder fillers, the performance of the coating can be improved, reducing problems such as shrinkage, cracking, and curling that occur during edge coating, thereby further enhancing the performance stability and durability of the battery. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments are briefly described below:

[0036] Figure 1 The image shows the appearance of the aqueous slurry coating suitable for edge coating of lithium battery negative electrode obtained in Example 3.

[0037] Figure 2 This is a graph showing the test results of the room temperature resistance to cross-contamination of the aqueous slurry suitable for edge coating of lithium battery negative electrodes obtained in Example 3.

[0038] Figure 3 The graph shows the CV test results of the waterborne acrylic resin adhesive obtained in Example 3.

[0039] Figure 4 The image shows the electrolyte resistance test results of the aqueous slurry obtained in Example 3, which is suitable for coating the edge of the negative electrode of a lithium battery. Detailed Implementation

[0040] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0041] Preparation Example 1: Preparation of Waterborne Acrylic Resin Adhesive

[0042] A method for preparing water-based acrylic resin adhesives includes the following steps:

[0043] S21, Base Component: According to the mass fraction: add 5g of sodium polyacrylate to 1000g of deionized water, heat to 80℃, stir at high speed for 20min, and after the protective colloid is completely dissolved, cool to 50℃; then add in sequence: 30g of methyl acrylate, 20g of acrylamide, and 5g of vinyl acetate, stir and mix evenly, heat to 70℃ to obtain component A;

[0044] S22. Polymerization reaction: Add 0.5g of ammonium persulfate to 50g of deionized water and stir to mix evenly to obtain an ammonium persulfate solution; add the ammonium persulfate solution dropwise to component A, controlling the dropping rate, and complete the dropping within 2 hours. After the dropping is completed, raise the temperature to 85℃ and continue to keep it at that temperature for 2 hours. Add another 0.1g of ammonium persulfate and keep it at that temperature for 1 hour. Then lower the temperature to stop the reaction. When the temperature drops below 40℃, discharge the material to obtain the water-based acrylic resin adhesive.

[0045] Preparation Example 2: Preparation of Waterborne Acrylic Resin Adhesive

[0046] A method for preparing water-based acrylic resin adhesives includes the following steps:

[0047] S21, Base Component: According to the following mass proportions: 10g of hydroxyethyl cellulose is added to 1500g of deionized water, heated to 90℃, stirred at high speed for 30min, and after the protective colloid is completely dissolved, the temperature is lowered to 70℃; then 60g of ethyl acrylate, 50g of itaconic acid, and 10g of styrene are added in sequence, stirred and mixed evenly, and heated to 85℃ to obtain component A;

[0048] S22. Polymerization reaction: Add 2g of potassium persulfate to 50g of deionized water and stir to mix evenly to obtain potassium persulfate solution; add potassium persulfate solution dropwise to component A, control the dropping rate, and complete the dropping over 3 hours. After the dropping is completed, raise the temperature to 85℃ and keep it at that temperature for 3 hours. Add 0.5g of potassium persulfate and keep it at that temperature for 1 hour. Then lower the temperature to stop the reaction. When the temperature drops below 40℃, discharge the material to obtain water-based acrylic resin adhesive.

[0049] Preparation Example 3: Preparation of Waterborne Acrylic Resin Adhesive

[0050] A method for preparing water-based acrylic resin adhesives includes the following steps:

[0051] S21, Base Component: According to the mass fraction: add 8g of sodium carboxymethyl cellulose to 1200g of deionized water, heat to 85℃, stir at high speed for 25min, and after the protective colloid is completely dissolved, cool to 60℃; then add in sequence: 45g of butyl acrylate, 40g of ethyl carboxyacrylate, and 8g of acrylonitrile, stir and mix evenly, and heat to 75℃ to obtain component A;

[0052] S22. Polymerization reaction: Add 1g of sodium persulfate to 50g of deionized water and stir to mix evenly to obtain sodium persulfate solution; add sodium persulfate solution dropwise to component A, controlling the dropping rate, and complete the dropping over 2.5 hours. After the dropping is completed, raise the temperature to 85℃ and keep it at that temperature for 2.5 hours. Add 0.3g of sodium persulfate and keep it at that temperature for 1 hour. Then lower the temperature to stop the reaction. When the temperature drops below 40℃, discharge the material to obtain water-based acrylic resin adhesive.

[0053] Preparation Example 4: Preparation of Modified Inorganic Powder Fillers

[0054] The preparation method of modified inorganic powder fillers includes the following steps:

[0055] S81. According to the mass fractions, 1g of γ-glycidoxypropyltrimethoxysilane is mixed with 100g of ethanol and 30g of water, and stirred evenly to obtain mixture A;

[0056] S82. Add 80g of boehmite and 40g of alumina to mixture A, then heat to 43℃ and stir at 200r / min for 90min. Finally, filter, wash, dry and grind at 75℃ to obtain the modified inorganic powder filler.

[0057] Example 1

[0058] An aqueous slurry suitable for edge coating of lithium battery negative electrode, comprising, by mass parts: 2.5g of aqueous acrylic resin adhesive and 97.5g of boehmite, wherein the aqueous acrylic resin adhesive is prepared in Preparation Example 1;

[0059] The above-mentioned method for preparing an aqueous slurry suitable for edge coating of lithium battery negative electrode includes the following steps:

[0060] By mass fraction, water-based acrylic resin adhesive and boehm-free material are placed in a mixing tank and dispersed by high-speed stirring at 1000 rpm for 2 hours to obtain a water-based slurry suitable for edge coating of lithium battery negative electrode.

[0061] Example 2

[0062] An aqueous slurry suitable for edge coating of lithium battery negative electrode, comprising, by mass parts: 2g of aqueous acrylic resin adhesive and 98g of alumina, wherein the aqueous acrylic resin adhesive is prepared in Preparation Example 2.

[0063] The above-mentioned method for preparing an aqueous slurry suitable for edge coating of lithium battery negative electrode includes the following steps:

[0064] By mass fraction, water-based acrylic resin adhesive and alumina are placed in a mixing tank and dispersed by high-speed stirring at 2000 rpm for 1 hour to obtain a water-based slurry suitable for edge coating of lithium battery negative electrode.

[0065] Example 3

[0066] An aqueous slurry suitable for edge coating of lithium battery negative electrode, comprising, by mass parts: 2.5g of aqueous acrylic resin adhesive and 97.5g of modified inorganic powder filler, wherein the aqueous acrylic resin adhesive was prepared in Preparation Example 3 and the modified inorganic powder filler was prepared in Preparation Example 4;

[0067] The above-mentioned method for preparing an aqueous slurry suitable for edge coating of lithium battery negative electrode includes the following steps:

[0068] According to the mass fraction, the water-based acrylic resin adhesive and the modified inorganic powder filler are placed in a mixing tank and dispersed at high speed of 1500 rpm for 1.5 h to obtain a water-based slurry suitable for edge coating of lithium battery negative electrode.

[0069] Example 4

[0070] Same as Example 3, except that an equal amount of boehmite is used instead of the modified inorganic powder filler.

[0071] Example 5

[0072] Similar to Example 3, except that an equal amount of alumina is used instead of the modified inorganic powder filler.

[0073] Performance testing

[0074] Samples of the aqueous slurries prepared in Examples 1-5 for edge coating of lithium battery negative electrodes were taken and tested. The test results are shown in Table 1.

[0075] (1) Peel strength test: A water-based slurry suitable for edge coating of lithium battery negative electrode is coated on copper foil on a laboratory coating machine. The coated edge coating is placed in a 120℃ oven to dry. The dry film thickness is about 50-60μm. The dried coating is cut into 5cm wide and 12.5cm long dimensions for 180-degree horizontal peel strength test.

[0076] (2) Resistance to cross-contamination of negative electrode slurry: Use a pipette to draw a certain amount of water-based slurry and negative electrode slurry suitable for edge coating of lithium battery negative electrode, place them on copper foil, and bring the two slurries into contact to observe the cross-contamination phenomenon.

[0077] (3) Electrolyte resistance: The coated edge coating is immersed in the electrolyte, and the appearance of the electrode is tested after immersion in the electrolyte at 25°C for 72 hours (whether the coating peels off, etc.).

[0078] (4) Chemical stability: Water-based acrylic resin adhesive was placed in a PTFE plate and dried at 45°C to obtain an adhesive film. The adhesive film was cut into appropriate sizes, dried at 105°C for 4 hours, and weighed to obtain the initial mass of the adhesive film. The adhesive film was immersed in an electrolyte and its mass swelling rate was tested after immersion in the electrolyte at 60°C for 72 hours (swelling rate = (mass of the adhesive film after swelling - initial mass of the adhesive film) / initial mass of the adhesive film * 100%).

[0079] (5) Electrochemical stability: The water-based acrylic resin adhesive prepared in Example 3 was placed in a PTFE plate and dried at 45°C to obtain a film. The film was cut into appropriate sizes and made into a button cell for CV testing to check whether there was a reaction peak in the 0-3V range.

[0080] Table 1 Performance Tests

[0081] project Peel strength (N) Resistance to material cross-contamination Electrolyte resistant Swelling rate / % Example 1 0.65 No cross-contamination Normal, no shedding 2.6 Example 2 0.54 No cross-contamination Normal, no shedding 3.1 Example 3 0.98 No cross-contamination Normal, no shedding 1.9 Example 4 0.61 No cross-contamination Normal, no shedding 2.9 Example 5 0.65 No cross-contamination Normal, no shedding 2.8

[0082] As shown in Table 1, the aqueous slurry prepared in Examples 1-5 for edge coating of lithium battery negative electrodes has good coating adhesion, flexibility, and coating appearance. At the same time, no interpenetration occurs when it comes into contact with the negative electrode slurry, which solves the problem of burrs and powder shedding that easily occur during the cutting process of negative electrode sheets.

[0083] Table 1 shows that the performance comparison of the aqueous slurry suitable for edge coating of lithium battery negative electrodes prepared in Examples 3 and 4-5 reveals that the modified inorganic powder filler, composed of boehmite and alumina in a mass ratio of 2:1 and modified with γ-glycidyl etheroxypropyltrimethoxysilane, achieves better compatibility and dispersibility with the aqueous acrylic resin adhesive through silane modification, thereby enhancing the peel strength of the coating. This effectively improves coating performance, reduces problems during the cutting process, and provides a better solution for edge coating of lithium battery negative electrodes.

[0084] Figure 1 The image shows the appearance of the aqueous slurry coating suitable for edge coating of lithium battery negative electrodes obtained in Example 3; from Figure 1 It can be seen that when the thickness of the single-sided edge coating is about 50-60um, the slurry has excellent dispersibility, the coating surface is smooth, there are no particles, and there is basically no cracking; the electrode has high flexibility and does not crack when folded.

[0085] Figure 2 This is a graph showing the test results of the room-temperature resistance to cross-contamination of the aqueous slurry suitable for edge coating of lithium battery anodes obtained in Example 3; from... Figure 2 It can be seen that the aqueous slurry obtained in Example 3, suitable for coating the edge of the negative electrode of a lithium battery, can effectively prevent cross-contamination between the slurry and the negative electrode slurry. Furthermore, when coated together with the negative electrode slurry and dried in a 100°C oven, there is no cross-contamination between the slurry and the negative electrode slurry during the drying process, and the boundary remains clear.

[0086] Figure 3 The graph shows the CV test results of the waterborne acrylic resin adhesive obtained in Example 3; from Figure 3 It can be seen that there is no reaction peak in the 0-3V range.

[0087] Figure 4 The graph shows the electrolyte resistance test results of the aqueous slurry suitable for coating the negative electrode edge of a lithium battery obtained in Example 3; from Figure 4 It can be seen that the coating of the electrode did not peel off after being soaked in electrolyte at 25°C for 72 hours, indicating good electrolyte resistance.

[0088] The above embodiments are only used to explain the technical solutions of this application and are not intended to limit it. Although the above embodiments have provided specific descriptions of this application, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation methods of this application. Any modifications and equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of this application.

Claims

1. An aqueous slurry suitable for edge coating of lithium battery negative electrode, characterized in that, The raw materials, by weight, include: 2-2.5 parts of water-based acrylic resin adhesive and 97.5-98 parts of inorganic powder filler, wherein the preparation method of the water-based acrylic resin adhesive includes the following steps: S11, Base Component: According to the following mass percentages: add 5-10 parts of protective colloid to 1000-1500 parts of deionized water, heat to 80-90℃, stir at high speed for 20-30 minutes, and after the protective colloid is completely dissolved, cool to 50-70℃; then add in sequence: 30-60 parts of acrylic monomer, 20-50 parts of water-soluble monomer and 5-10 parts of functional monomer, stir and mix evenly, heat to 70-85℃ to obtain component A; S12. Polymerization reaction: Add 0.5-2 parts of initiator to 50 parts of deionized water and stir to mix evenly to obtain an initiator solution; Add the initiator solution dropwise to component A, controlling the dropping rate, and complete the dropping over 2-3 hours. After the dropping is completed, raise the temperature to 85℃ and continue to keep it at that temperature for 2-3 hours. Add 0.1-0.5 parts of initiator and keep it at that temperature for 1 hour. Then lower the temperature to stop the reaction. When the temperature drops below 40℃, discharge the material to obtain the water-based acrylic resin adhesive. The acrylic monomers are one or more selected from methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, isooctyl acrylate, methyl methacrylate, and ethyl methacrylate. The water-soluble monomer is one or more of acrylamide, hydroxymethylacrylamide, itaconic acid, hydroxypropyl acrylate, and carboxyethyl acrylate; The functional monomer is at least one of acrylonitrile, vinyl acetate, and styrene; the inorganic powder filler is at least one of boehmite and alumina.

2. The aqueous slurry for edge coating of lithium battery negative electrode according to claim 1, characterized in that, The protective adhesive is one or a mixture of two of sodium polyacrylate, sodium carboxymethyl cellulose, hydroxyethyl cellulose, and polyvinyl alcohol.

3. The aqueous slurry for edge coating of lithium battery negative electrode according to claim 1, characterized in that, The initiator is one of ammonium persulfate, potassium persulfate, and sodium persulfate.

4. The aqueous slurry for edge coating of lithium battery negative electrode according to claim 1, characterized in that, The inorganic powder filler is a modified inorganic powder filler, which is composed of boehmite and alumina in a mass ratio of 2:1 and is prepared by silane modification. Its preparation method includes the following steps: S21. According to the mass fraction, mix 1 part of γ-glycidoxypropyltrimethoxysilane with 100 parts of ethanol and 30 parts of water, stir evenly, and obtain mixture A; S22. Add 80 parts boehmite and 40 parts alumina to mixture A, then heat to 43°C, stir at 200 r / min for 90 min, and finally filter, wash, dry and grind at 75°C to obtain modified inorganic powder filler.

5. A method for preparing an aqueous slurry suitable for edge coating of a lithium battery negative electrode as described in any one of claims 1-4, characterized in that, The process includes the following steps: by mass, water-based acrylic resin adhesive and inorganic powder filler are placed in a mixing tank and dispersed at high speed of 1000-2000 rpm for 1-2 hours to obtain a water-based slurry suitable for edge coating of lithium battery negative electrode.

6. The application of an aqueous slurry as described in any one of claims 1-4, suitable for edge coating of lithium battery negative electrode sheets, is characterized in that... The aqueous slurry is coated on the edge of the negative electrode sheet and dried and cured at a temperature of 80-130℃, with an edge coating thickness of 50-70μm.

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