Anti-cracking additive for lithium ion battery negative electrode and preparation method and application thereof

Abstract

This application discloses an anti-cracking additive for lithium-ion battery anodes, its preparation method, and its application. The anti-cracking additive has the following weight composition: 5%~25% high-boiling-point polar solvent; 10%~25% flexible segment modifier; 10%~30% polymeric toughening agent; 5~10% nonionic surfactant; and water as the balance. The high-boiling-point polar solvent is an organic solvent with a boiling point higher than 150℃; the flexible segment modifier is a polyether compound; and the polymeric toughening agent is a styrene-acrylate copolymer emulsion or a polyurethane dispersion. Through the synergistic effect of its multiple components, the anti-cracking additive exhibits excellent anti-cracking performance. When this anti-cracking additive is added to the lithium-ion battery anode slurry, the prepared electrode sheet shows no visible cracks after rolling, and no active material detachment is observed during a 180° bending test.

Description

Technical Field

[0001] This application relates to the field of lithium-ion batteries, and in particular to an anti-cracking agent for the negative electrode of a lithium-ion battery, its preparation method, and its application. Background Technology

[0002] In the field of lithium-ion batteries, silicon-based anode materials (such as silicon-carbon composites) have become one of the key directions for improving battery energy density due to their theoretical specific capacity, which is much higher than that of traditional graphite. However, these materials undergo severe volume expansion (>300%) during lithium insertion / extraction. The resulting huge internal stress easily leads to cracking, pulverization, and peeling of the electrode coating from the current collector, resulting in a sharp decline in battery capacity and a significant reduction in cycle life. This problem seriously restricts their large-scale commercial application.

[0003] To address these challenges, the industry generally adopts a strategy of adding specialized anti-cracking agents (or binders and dispersants with anti-cracking functions) to the negative electrode slurry. This enhances the mechanical toughness of the electrode and optimizes stress distribution, effectively maintaining the integrity of the electrode structure. For example, patent document CN117801173A discloses an anti-cracking agent for lithium-ion battery negative electrode sheets. This agent is prepared using a multi-component system through a complex multi-step polymerization process, aiming to simultaneously improve adhesion and flexibility through various chemical bonding effects. However, the preparation of this agent requires multiple independent synthesis reactions in the aqueous and organic phases, making the process cumbersome and time-consuming. In addition, the pretreatment process of its polyether ester macromonomer requires the use of carbon tetrachloride (CCl4), which is highly toxic and has poor environmental compatibility. This not only increases the difficulty of post-processing and waste disposal costs but also poses potential risks to safe production and environmental protection. Another patent document, CN119275287A, proposes adding N-methylpyrrolidone (NMP) as an additive to traditional negative electrode slurry to reduce coating cracking by improving the slurry's rheological properties. However, NMP poses a risk of solvent residue, which can easily trigger battery side reactions and impair cycle stability; at the same time, its significant reproductive toxicity and environmental hazards are seriously inconsistent with the concept of green manufacturing.

[0004] Therefore, there is an urgent need to develop a new type of anti-cracking agent for anodes. This agent must simultaneously meet the core requirements of simple and green preparation process, excellent long-term electrochemical stability, good ion and electron conductivity, and excellent compatibility with electrode slurry system, so as to provide a practical and effective technical solution for the reliable application of high-capacity silicon-carbon anodes. Summary of the Invention

[0005] Based on this, this application provides an anti-cracking additive for the negative electrode of lithium-ion batteries. It has stable electrochemical performance, and when added in small amounts to the negative electrode slurry of lithium-ion batteries, it can achieve excellent anti-cracking effect. Moreover, the preparation process of the anti-cracking additive is green and environmentally friendly.

[0006] A crack-resistant additive for the negative electrode of a lithium-ion battery, wherein the crack-resistant additive has the following weight composition:

[0007] High-boiling-point polar solvents: 5%~25%;

[0008] Flexible segment modifier 10%~25%;

[0009] Polymer toughening agent 10%~30%;

[0010] Nonionic surfactants: 5-10%;

[0011] Water balance;

[0012] The high-boiling-point polar solvent is an organic solvent with a boiling point higher than 150°C; the flexible segment modifier is a polyether compound; and the polymer toughening agent is a styrene-acrylate copolymer emulsion or a polyurethane dispersion.

[0013] The anti-cracking additive provided in this application does not use toxic organic solvents such as N-methylpyrrolidone (NMP) and CCl4, but uses water as a solvent. This can avoid the occurrence of battery side reactions due to organic solvent residues, which would cause cycle life degradation and meet the requirements of green manufacturing.

[0014] The high-boiling-point solvent has good solubility and can dissolve flexible segment modifiers and polymer toughening agents, effectively adjusting the rheological properties of lithium-ion battery negative electrode slurry. In addition, the high-boiling-point solvent can extend the drying time of the negative electrode slurry. That is, in the drying process of preparing electrode sheets using negative electrode slurry, when the high-boiling-point solvent has not evaporated, it can ensure that the system is in a moist state for as long as possible, preventing cracks and bubbles from appearing.

[0015] The flexible segment modifier imparts good deformation capability to the coating formed by drying the lithium-ion battery negative electrode slurry through the flexibility of the molecular chain. Under relatively small stress, the coating itself provides a buffer to prevent cracking.

[0016] The polymer toughening agent forms a three-dimensional network structure through molecular chain entanglement and hydrogen bonding, effectively reducing the stress generated by volume changes in the lithium-ion battery negative electrode slurry before and after drying, thus preventing cracking.

[0017] The nonionic surfactant is used to improve the dispersion stability and interfacial compatibility of each component, thereby improving the stability and uniformity of the crack-resistant additive.

[0018] This application significantly improves the interfacial properties of lithium-ion battery anode slurry by synergistically compounding nonionic surfactants with high-boiling-point polar solvents. This reduces the surface tension and dynamic wetting time of the lithium-ion battery anode slurry. The lithium-ion battery anode slurry can quickly penetrate and spread uniformly in the porous structure formed by the hydrophobic anode active material and conductive agent, effectively eliminating coating defects such as pinholes and spots caused by insufficient wetting. In addition, this compounding system forms a stable wetting layer on the surface of the active material through the directional adsorption of surfactants and the synergistic effect of polar solvents, improving the storage stability of the slurry and ensuring uniform distribution of the binder during subsequent drying. Ultimately, the prepared electrode has superior conductive network integrity and structural consistency.

[0019] The anti-cracking additive for lithium-ion battery anodes provided in this application exhibits excellent stability. It passed the stability test at 3000 rpm for 30 min. After being sealed and stored at room temperature (10~30℃) for 6 months, there was no stratification or precipitation. The viscosity change rate was less than 5%, the viscosity (25℃) was ≤250 mPa·s, and the pH value was stable between 7.5 and 8.5 with a pH fluctuation range of <0.3. It is fully compatible with existing lithium-ion battery anode slurry production processes and can be directly added to the anode slurry system.

[0020] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0021] Optionally, the high-boiling-point polar solvent is at least one of 1,3-butanediol, 1,2-propanediol, and 1,3-propanediol.

[0022] Optionally, the flexible segment modifier is polyethylene glycol or polypropylene oxide, wherein the number average molecular weight of the polyethylene glycol is 200-1000, and the number average molecular weight of the polypropylene oxide is 200-1000.

[0023] Optionally, the nonionic surfactant is at least one of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether, wherein the EO number of the alkylphenol polyoxyethylene ether and the fatty alcohol polyoxyethylene ether is 8 to 12.

[0024] The EO number, also known as the length of the polyoxyethylene chain, determines the hydrophilicity of nonionic surfactants. The alkylphenol polyoxyethylene ether can be nonylphenol polyoxyethylene ether or octylphenol polyoxyethylene ether.

[0025] Ethylene oxide addition number (EO number) of 8-12, within which the molecule exhibits balanced hydrophilicity and hydrophilicity, with an HLB value of approximately 12-14, is suitable for electrode slurry systems, achieving a better balance between slurry dispersion stability and foam control. The optimal EO number is 10.

[0026] Optionally, the crack-resistant additive has the following composition by weight:

[0027] 1,3-Butanediol 10%~20%;

[0028] PEG-200 10%~20%;

[0029] 15%~25% styrene-butyl acrylate copolymer emulsion;

[0030] Fatty alcohol polyoxyethylene ether 5%~10%;

[0031] Water balance.

[0032] Optionally, the styrene-butyl acrylate copolymer emulsion has a viscosity of less than 500 mPa·s at 25°C (measured by a rotational viscometer) and a solid content of 40%~50%.

[0033] The styrene-butyl acrylate copolymer emulsion has a glass transition temperature of 0℃ to -15℃, a particle size of less than 0.15µm, no demulsification after centrifugation at 3000rpm for 30 minutes, a pH value of 6.0 to 9.0, and an average particle size of less than 0.15µm. The film-forming temperature range of the styrene-butyl acrylate copolymer emulsion is -15℃ to 25℃. Within this range, it can ensure that the emulsion forms a continuous film in the early stage of electrode drying, thus better balancing film-forming efficiency and energy consumption control.

[0034] Optionally, the polyurethane dispersion has a viscosity of less than 500 mPa·s (measured by a rotational viscometer) at 25°C and a solid content of 40%~50%. The polyurethane dispersion is a hydrophilic emulsion with an average particle size of less than 0.15 µm. It does not break down after centrifugation at 3000 rpm for 30 minutes, has a stable pH value of 6.5~8.5, does not freeze or separate when stored at low temperature (-5°C), has a glass transition temperature of 0°C to -15°C, and a film-forming temperature range of 10°C to 40°C. This range ensures that the polymer particles can form a continuous and dense coating during electrode drying.

[0035] Optionally, the viscosity change rate of the anti-cracking additive is less than 5% over 12 months.

[0036] This application also provides a method for preparing the aforementioned anti-cracking additive for lithium-ion battery anodes, comprising:

[0037] Step 1: Heat the polymer toughening agent to 30~60℃ and stir continuously for at least 30 minutes to obtain a pretreated polymer toughening agent;

[0038] Step 2: After the high-boiling-point polar solvent and the flexible segment modifier are mixed evenly, they are added to the pretreated polymer toughening agent and mixed evenly at 30~60℃ to obtain an intermediate solution.

[0039] Step 3: Add the nonionic surfactant to an intermediate solution at 30-60°C, then add solvent and mix evenly at 30-60°C. After aging, obtain the anti-cracking additive for lithium-ion battery anodes.

[0040] The method for preparing the anti-cracking additive provided in this application does not require a complex multi-step synthesis process, nor does it involve the use of high-risk reagents. The process is simple, more environmentally friendly and safer.

[0041] In this application, the polymer toughening agent is an emulsion or dispersion. The system is kept uniform and free of sedimentation by heating and continuous stirring. A low stirring speed of 200-300 rpm is sufficient.

[0042] A high-boiling-point polar solvent and a flexible segment modifier are mixed at room temperature and stirred at a low speed of 300-600 rpm for at least 10 minutes to form a homogeneous and transparent solution.

[0043] A transparent solution formed by a high-boiling-point polar solvent and a flexible segment modifier is slowly added to the polymer toughening agent, and the mixture is stirred continuously for at least 30 minutes to ensure uniform mixing (if a styrene-butyl acrylate copolymer emulsion is used as the polymer toughening agent, the mixture will be a uniform milky white liquid). Then, a nonionic surfactant is added. The nonionic surfactant is a liquid and can be diluted with an equal mass of water before being added to the system. Finally, the remaining water is slowly added to adjust the solid content. The resulting product is allowed to stand at 25-35°C for at least 24 hours to mature, thus obtaining the crack-resistant agent (if a styrene-butyl acrylate copolymer emulsion is used as the polymer toughening agent, the crack-resistant agent will be a semi-transparent emulsion).

[0044] The method for preparing the anti-cracking agent provided in this application can effectively avoid demulsification and phase separation caused by excessively high local concentrations through stepwise feeding and gradient stirring strategies. The pretreatment of the polymer toughening agent and the final curing process ensure the molecular-level dispersion and stability of each component. The temperature is controlled at 30~60℃ throughout the process to ensure that the polymer chains are fully extended without degradation.

[0045] The method for preparing the anti-cracking agent in this application mainly involves mixing at low temperatures, and the entire process can be controlled within 2.5 hours. Compared with multi-step high-temperature polymerization (such as the technical solution disclosed in patent document CN117801173A), the production cycle is shortened by 75%, which can greatly reduce energy consumption.

[0046] Using water as a solvent can significantly reduce raw material costs compared to N-methylpyrrolidone (NMP), and it is perfectly compatible with existing lithium-ion battery anode production lines without the need for special equipment, saving a lot of equipment modification costs. The entire preparation process is carried out at low temperatures, eliminating the safety hazards caused by flammable and explosive solvents.

[0047] The method for preparing the anti-cracking additive provided in this application has good process stability. After verification through 10 batches of continuous production, the product viscosity deviation is <3% and the solid content deviation is <0.5%.

[0048] This application also provides a lithium-ion battery negative electrode slurry, which contains the aforementioned anti-cracking agent, wherein the amount of the anti-cracking agent added is 0.1% to 0.3% of the solid content of the negative electrode slurry.

[0049] The anti-cracking additive exhibits excellent anti-cracking performance through the synergistic effect of its multiple components. When this anti-cracking additive is added to the lithium-ion battery negative electrode slurry, the prepared electrode sheet, after rolling, has a compaction density of 1.6 g / cm³. 3 No visible cracks were found, and no active material was detached during the 180° bending test.

[0050] Adding the anti-cracking agent provided in this application to the manufacturing process of silicon-carbon anode sheets for lithium-ion batteries exhibits excellent structural integrity, with a yield of 1.6 g / cm³. 3 No visible cracks were found after high-pressure compaction rolling, and no active material detachment was observed during the 180° bending test. This effectively solved the cracking problem of high-capacity silicon-based anode materials. At the same time, it achieved breakthrough progress in economic benefits, environmental friendliness, and production safety, providing reliable technical support for the large-scale commercial application of silicon-carbon anodes. Attached Figure Description

[0051] Figure 1 A photograph of the electrode sheet prepared in Example 1;

[0052] Figure 2 A photograph of the electrode sheet prepared in Example 2;

[0053] Figure 3 A photograph of the electrode sheet prepared in Example 3;

[0054] Figure 4 A photograph of the electrode prepared for Comparative Example 1;

[0055] Figure 5 Photographs of the electrodes prepared for Comparative Example 2;

[0056] Figure 6 A photograph of the anti-cracking agent prepared in Example 1. Detailed Implementation

[0057] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] To better describe and illustrate the embodiments of this application, reference may be made to one or more accompanying drawings, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the inventive creations of this application, the embodiments or preferred methods described herein.

[0059] It should be noted that when a component is said to be "connected" to another component, it can be directly connected to the other component or it can be connected to a component in between. When a component is said to be "set on" another component, it can be directly set on the other component or it may be set to a component in between.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0061] Example 1

[0062] A crack-resistant additive for lithium-ion battery anodes comprises, by weight: 5% 1,3-butanediol (i.e., a high-boiling-point polar solvent), 10% PEG-200 (i.e., a flexible segment modifier), 30% styrene-butyl acrylate copolymer emulsion (styrene-acrylic emulsion, i.e., a polymer toughening agent), 10% fatty alcohol polyoxyethylene ether AEO-10 ​​(i.e., a nonionic surfactant), and 45% deionized water.

[0063] The preparation method of the anti-cracking additive includes the following steps:

[0064] (1) The styrene-butyl acrylate copolymer emulsion was preheated in a water bath at 40°C and stirred at a low speed of 250 rpm for 30 minutes to ensure that the emulsion system was uniform and free from sedimentation.

[0065] (2) At the same time, 1,3-butanediol and PEG-200 are stirred at 500 rpm for 10 minutes at room temperature to form a homogeneous and transparent solution.

[0066] (3) Add the transparent solution from step (2) to the styrene-butyl acrylate copolymer emulsion from step (1) and continue stirring for 30 minutes until the system is a uniform milky white liquid.

[0067] (4) Dilute the fatty alcohol polyoxyethylene ether with an equal mass of deionized water to a concentration of 50% and add it to the milky white liquid in step (3). Finally, slowly add the remaining deionized water to adjust the solid content. Let the obtained product stand at 25°C for 12 hours to obtain a semi-transparent emulsion product.

[0068] Preparation of lithium-ion battery negative electrode slurry: The negative electrode slurry was prepared according to the weight ratio of silicon-carbon negative electrode material (silicon content 15%): SBR (styrene-butadiene rubber latex): CMC (sodium carboxymethyl cellulose): polyacrylic acid binder: deionized water = 97.5:1:0.5:25:58. After stirring at 500 rpm for 30 min, 0.1% of an anti-cracking additive (the solid content of the slurry refers to the sum of the mass of all solids in the slurry that do not volatilize during the electrode drying process, excluding the anti-cracking additive) was weighed and added to the slurry. Finally, vacuum degassing was performed to obtain the negative electrode slurry. The viscosity of the negative electrode slurry, the standing viscosity, and the appearance of the thick-coated electrode were tested.

[0069] Examples 2-9 and Comparative Examples 1-8

[0070] The formulations for each embodiment and comparative example are shown in Table 1.

[0071] Table 1

[0072]

[0073] In Table 1, PEG-200: polyethylene glycol with a molecular weight of 200;

[0074] PEG-2000: Polyethylene glycol with a molecular weight of 2000;

[0075] PPG-800: Polypropylene oxide with a molecular weight of 800;

[0076] PPG-2000: Polypropylene oxide with a molecular weight of 2000;

[0077] AEO-10: Fatty alcohol polyoxyethylene ether-10, a fatty alcohol ether with 10 EOs;

[0078] AEO-15: Fatty alcohol polyoxyethylene ether-15, a fatty alcohol ether with 15 EOs;

[0079] OP-7: Octylphenol polyoxyethylene ether-7, an octylphenol ether with 7 EOs;

[0080] OP-10: Octylphenol polyoxyethylene ether-10, an octylphenol ether with 10 EOs;

[0081] PUD: Polyurethane dispersion.

[0082] Table 1 lists the anti-cracking agents prepared in each embodiment and comparative example. The preparation process is the same as that in Example 1. Comparative Example 1 refers to the preparation of lithium-ion battery negative electrode slurry without adding any anti-cracking agent. Comparative Example 2 refers to the preparation of lithium-ion battery negative electrode slurry with NMP of 0.6% solid content as anti-cracking agent.

[0083] The drugs used in Table 1 and their manufacturers' brands are shown in Table 2.

[0084] Table 2

[0085]

[0086] Performance Characterization

[0087] The performance of the anti-cracking additives prepared in each embodiment and comparative example was characterized. The changes in viscosity and pH value over 180 days are detailed in Table 3. The viscosity in Table 3 was measured at 25°C.

[0088] Table 3

[0089]

[0090] As can be seen from Table 3, the viscosity change rate of the anti-cracking agents prepared in each embodiment is less than 4% within 180 days, and the pH fluctuation is minimal, indicating that their storage stability is good.

[0091] The performance of the lithium-ion battery anode slurry prepared in each embodiment and comparative example was characterized. The viscosity change over 24 hours is shown in Table 4, where the viscosity unit is mPa·s.

[0092] Table 4

[0093]

[0094] As shown in Table 4, the viscosity change rate of the lithium-ion battery anode slurry prepared in Examples 1-9 was relatively small over 24 hours, while the viscosity change rate of the lithium-ion battery anode slurry in each comparative example was relatively large over 24 hours.

[0095] The negative electrode slurries prepared in each embodiment and comparative example were coated on the surface of the substrate with a coating thickness of 400µm. The electrode sheets were dried at 150℃, and the cracking of the electrode sheets at different drying times was observed. The results are shown in Table 5.

[0096] Table 5

[0097]

[0098] Photographs of the electrode sheets prepared using the negative electrode slurries provided in the various embodiments and comparative examples are shown below. Figures 1-5 As shown, the electrodes of Examples 1 to 3 did not crack after drying for 30 minutes, while Comparative Example 1 cracked after drying for 15 minutes, and Comparative Example 2 cracked after drying for 25 minutes.

[0099] The areal density, peel strength, bending test performance, and number of folds of the electrode sheets prepared using the negative electrode slurries provided in the various embodiments and comparative examples are detailed in Table 6.

[0100] Table 6

[0101]

[0102] In Table 6, the lithium-ion battery negative electrode slurry was coated onto the substrate and dried. The areal density of the dried coating was measured. Then, the coating was further rolled. After rolling, peel strength, bending and folding tests were performed.

[0103] The anti-cracking agents prepared in each embodiment were used in the lithium-ion battery negative electrode slurry to make electrodes, and the compaction density reached 1.6 g / cm³ after rolling. 3 No visible cracks were found, while the comparative sample showed obvious microcracks under the same conditions.

[0104] When the anti-cracking agents prepared in each embodiment are used in the negative electrode slurry of lithium-ion batteries, they can prevent cracking and increase the peel strength. No cracking occurs in the bending test using wire rods. In the folding test, the electrode sheet made of the negative electrode slurry using the anti-cracking agents prepared in each embodiment cracks after multiple bends, while in the comparative example, most of the coatings peel off after one fold.

[0105] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An anti-cracking aid for a lithium-ion battery negative electrode, characterized in that, The anti-cracking additive has the following composition by weight: High-boiling-point polar solvents: 5%~25%; Flexible segment modifier 10%~25%; Polymer toughening agent 10%~30%; Nonionic surfactants: 5-10%; Water balance; The high-boiling-point polar solvent is at least one of 1,3-butanediol, 1,2-propanediol, and 1,3-propanediol. The flexible segment modifier is polyethylene glycol or polypropylene oxide, wherein the number average molecular weight of polyethylene glycol is 200-1000, and the number average molecular weight of polypropylene oxide is 200-1000. The polymer toughening agent is a styrene-acrylate copolymer emulsion or a polyurethane dispersion; The nonionic surfactant is at least one of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether, wherein the EO number of the alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether is 8 to 12.

2. The anti-cracking additive for lithium-ion battery negative electrode as described in claim 1, characterized in that, The anti-cracking additive has the following composition by weight: 1,3-Butanediol 10%~20%; PEG-200 10%~20%; 15%~25% styrene-butyl acrylate copolymer emulsion; Fatty alcohol polyoxyethylene ether 5%~10%; Water balance.

3. The anti-cracking additive for lithium-ion battery negative electrode as described in claim 1, characterized in that, The styrene-butyl acrylate copolymer emulsion has a viscosity of less than 500 mPa·s at 25°C and a solid content of 40%~50%.

4. The anti-cracking additive for lithium-ion battery negative electrode as described in claim 1, characterized in that, The polyurethane dispersion has a viscosity of less than 500 mPa·s at 25°C and a solid content of 40%~50%.

5. The anti-cracking additive for lithium-ion battery negative electrode as described in claim 1, characterized in that, The viscosity change rate of the anti-cracking additive is less than 5% over 12 months.

6. The method for preparing the anti-cracking additive for the negative electrode of a lithium-ion battery as described in any one of claims 1 to 5, characterized in that, include: Step 1: Heat the polymer toughening agent to 30~60℃ and stir continuously for at least 30 minutes to obtain a pretreated polymer toughening agent; Step 2: After the high-boiling-point polar solvent and the flexible segment modifier are mixed evenly, they are added to the pretreated polymer toughening agent and mixed evenly at 30~60℃ to obtain an intermediate solution. Step 3: Add the nonionic surfactant to an intermediate solution at 30-60°C, then add solvent and mix evenly at 30-60°C. After aging, obtain the anti-cracking additive for lithium-ion battery anode.

7. A lithium-ion battery negative electrode slurry, characterized in that, The anti-cracking agent as described in any one of claims 1 to 5 is added, wherein the amount of the anti-cracking agent added is 0.1% to 0.3% of the solid content of the negative electrode slurry.

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