Anti-cracking agent composition and use thereof

Abstract

The present invention relates to the technical field of batteries, and in particular to an anti-cracking agent composition and a use thereof. The anti-cracking agent composition comprises: 1,3-butanediol as component I, and component II corresponding to a peak appearing within a relative retention time range of 1.1-1.3 when the relative retention time of the 1,3-butanediol is set to 1.0 in gas chromatography analysis. In the anti-cracking agent composition, the content of the component II corresponding to the peak appearing within the relative retention time range of 1.1-1.3 is 1-1,000 ppm; and the balance is 1,3-butanediol. By means of a negative electrode material prepared from the anti-cracking agent composition of the present invention, the overall charging and discharging performance of a lithium battery can be significantly improved.

Description

A crack-resistant composition and its application Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to an anti-cracking agent composition and its application. Background Technology

[0002] 1,3-Butanediol is a colorless and odorless liquid. Its unique diol structure endows it with excellent chemical properties, leading to its wide application in daily chemical products, synthetic resins, and other industries. In recent years, in particular, its promising application characteristics in lithium-ion battery anodes have been discovered, expanding its market while simultaneously placing higher demands on its preparation optimization and product quality.

[0003] In the traditional process of preparing graphite anodes for lithium-ion batteries, the resulting graphite rolled films are prone to cracking, leading to unstable discharge performance. However, if graphite powder is dispersed in a solvent containing 1,3-butanediol during the preparation of the rolled graphite film, the cracking is significantly reduced after the solvent evaporates. The suitable chemical polarity of 1,3-butanediol helps to minimize graphite cracking.

[0004] However, when 1,3-butanediol products prepared using existing manufacturing methods are used as crack inhibitors, although the graphite rolled film does not crack, its discharge properties remain unstable. While the mechanism is not yet clear, it is believed to be related to byproducts contained in the 1,3-butanediol products.

[0005] To solve this problem, it is necessary to optimize the preparation process and purification process of 1,3-butanediol products to obtain highly purified 1,3-butanediol products, and to control the content of specific impurities within a certain range.

[0006] Patent documents JP6890708B2 and JP2021042214A disclose a method for controlling odor-producing impurities in 1,3-butanediol products, but they do not yet address impurities that affect lithium battery discharge in the application of lithium battery negative electrode anti-cracking agents, or methods for controlling such impurities.

[0007] In summary, in the field of using 1,3-butanediol products prepared by existing processes as anti-cracking agents for lithium battery anodes, it is urgent to identify the relevant impurities that affect lithium battery discharge and to further study methods for controlling these impurities.

[0008] Summary of the Invention

[0009] To address the above technical problems, this invention proposes an anti-cracking agent composition and its application. In the anti-cracking agent composition, when the relative retention time of 1,3-butanediol is set to 1.0, the content of the component corresponding to the peak appearing in the range of 1.1-1.3 relative retention time is controlled within the range of 1-1000 ppm. Thus, the impurities remaining in the negative electrode prepared by the anti-cracking agent composition will not adversely affect the overall charging and discharging performance of the lithium battery.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] In a first aspect, a crack-resistant composition based on 1,3-butanediol is provided, the crack-resistant composition comprising: 1,3-butanediol as component I, and component II corresponding to the peaks appearing in the range of 1.1-1.3 when the relative retention time of 1,3-butanediol is set to 1.0 under gas chromatography analysis;

[0012] In the anti-cracking agent composition, the content of component II corresponding to the peak appearing in the relative retention time range of 1.1-1.3 is 1-1000 ppm (e.g., 2 ppm, 4 ppm, 5 ppm, 8 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 80 ppm, 90 ppm, 120 ppm, 150 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 800 ppm, 900 ppm), preferably 1-200 ppm, more preferably 1-100 ppm (or it can be expressed as: the area fraction of component II corresponding to the peak appearing in the relative retention time range of 1.1-1.3 is 1-1000 ppm); the balance is 1,3-butanediol.

[0013] According to the anti-cracking composition provided by the present invention, in some embodiments, when the relative retention time of 1,3-butanediol is set to 1.0 under gas chromatography analysis, the structural formula of component II corresponding to the peak appearing in the range of 1.1-1.3 relative retention time is C6H 14 O2; its molecular weight is in the range of 118-119 g / mol.

[0014] In some embodiments, the component II corresponding to the peak appearing in the relative retention time range of 1.1-1.3 is 3-methyl-2,4-pentanediol and / or its isomers.

[0015] In some embodiments of the anti-cracking agent composition provided by the present invention, the conditions for gas chromatography analysis include:

[0016] Chromatographic column: capillary column; column material: fused silica;

[0017] Model / Stationary Phase: Model number DB-5, stationary phase is (5% phenyl)-methylpolysiloxane;

[0018] Column length: 30m;

[0019] Column inner diameter: 0.32mm;

[0020] Liquid film thickness: 0.25 μm;

[0021] Column temperature: Initial temperature 50℃, hold for 2 min, then increase to 80℃ at 5℃ / min, then increase to 280℃ at 15℃ / min and hold for 15 min;

[0022] Carrier gas: Nitrogen;

[0023] Carrier gas flow rate: 1.5 mL / min (constant flow mode);

[0024] Vaporization chamber temperature: 270℃;

[0025] Detector temperature: 280℃;

[0026] Injection volume: 1.0 μL;

[0027] Flow split ratio: 10:1;

[0028] Airflow rate: 400 mL / min;

[0029] Hydrogen gas flow rate: 30 mL / min;

[0030] Purging flow rate: 25 mL / min;

[0031] Injected sample: 1 μL of acetonitrile solution containing 10% by weight of the sample.

[0032] In a second aspect, the application of the anti-cracking agent composition as described above in the negative electrode sheet of a lithium battery is provided.

[0033] According to the application provided by the present invention, in some embodiments, the lithium battery negative electrode sheet is prepared by negative electrode slurry;

[0034] The negative electrode slurry comprises: a negative electrode active material, a conductive agent, a binder, and the aforementioned anti-cracking agent composition.

[0035] In some embodiments, the method for preparing the negative electrode slurry includes the following steps:

[0036] (1) Preparation of electrode dispersion: Mix water with the anti-cracking agent composition to prepare an anti-cracking agent aqueous solution; the concentration can be 0.5wt%-3wt% (e.g., 0.6wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 2.8wt%).

[0037] (2) Preparation of water-based adhesive solution: Mix the anti-cracking agent aqueous solution obtained above with the adhesive evenly to prepare a water-based adhesive solution;

[0038] (3) Preparation of slurry: Mix the negative electrode active material, conductive agent and the aqueous binder solution obtained above to form a uniform negative electrode slurry.

[0039] In this article, the dry base components of the negative electrode slurry may be a combination of negative electrode active material, conductive agent, binder and anti-cracking agent.

[0040] In this document, the viscosity of the negative electrode slurry is 3000-15000 mP·s (e.g., 3500 mP·s, 4000 mP·s, 5000 mP·s, 6000 mP·s, 7000 mP·s, 8000 mP·s, 10000 mP·s, 11000 mP·s, 12000 mP·s, 14000 mP·s, 14500 mP·s); and the solid content of the negative electrode slurry is 30-70 wt% (e.g., 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%).

[0041] In some embodiments, the amount of the anti-cracking agent composition in the negative electrode slurry is 0.1-2 wt% (e.g., 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 1.8 wt%), based on the total weight of all components.

[0042] In some embodiments, the negative electrode slurry, by total weight of all components:

[0043] The amount of the negative electrode active material is 75-98 wt% (e.g., 76 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 96 wt%).

[0044] The amount of the conductive agent used is 1-20 wt% (e.g., 2 wt%, 4 wt%, 5 wt%, 6 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%).

[0045] The amount of the adhesive used is 1-10 wt% (e.g., 2 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%, 9 wt%).

[0046] In some embodiments, the negative electrode active material is selected from one or more of graphite, silicon, silicon oxide, and silicon carbon.

[0047] In some embodiments, the conductive agent is selected from one or more of carbon black, carbon nanotubes, graphene, and carbon fibers.

[0048] In some embodiments, the adhesive is selected from one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene latex, acrylamide adhesives, acrylonitrile adhesives, polyvinyl alcohol, and sodium alginate adhesives.

[0049] The process for preparing lithium batteries based on the provided negative electrode sheet described in this article is a conventional choice in the field and will not be elaborated further here.

[0050] In this invention, the anti-cracking agent composition described above can be prepared by various methods. Those skilled in the art will understand that the following preparation methods are merely illustrative examples of how the anti-cracking agent composition with the above characteristics is obtained, and do not constitute any limitation.

[0051] For example, in some embodiments, the method for preparing the anti-cracking agent composition as described above includes the following steps:

[0052] (1) Acetaldehyde condensation: In the presence of an alkaline catalyst, acetaldehyde undergoes a condensation reaction to prepare a reaction mixture containing 3-hydroxybutyraldehyde. Then, unreacted acetaldehyde is removed to obtain a hydrogenation feedstock solution.

[0053] The condensation reaction process can use either a batch reactor or an external circulation reactor, and its mixing effect should be strictly controlled, with a batch reactor being preferred.

[0054] The linear velocity of the stirrer is controlled between 3.36 and 12.67 m / s (e.g., 3.5 m / s, 4.0 m / s, 5.0 m / s, 6.0 m / s, 8.0 m / s, 9.0 m / s, 10.0 m / s, 12.0 m / s), preferably between 6.18 and 9.62 m / s. At this stirring velocity, the reaction rate is moderate, the mixing effect is good, and the impurity content in the resulting product can be effectively controlled. When the stirring velocity is below 3.36 m / s, the material is not sufficiently mixed; when the stirring velocity is above 12.67 m / s, energy consumption increases sharply, the reaction temperature rises, and more impurities are generated. If an external circulation reactor is used, the same mixing effect as the above-mentioned batch reactor should be achieved.

[0055] (2) Hydrogenation reaction: In the presence of a hydrogenation catalyst, the hydrogenation feed liquid obtained in step (1) is subjected to a hydrolysis hydrogenation reaction to hydrogenate the 3-hydroxybutyraldehyde intermediate generated in the above reaction to generate a reaction liquid containing 1,3-butanediol.

[0056] (3) Distillation separation: The reaction solution containing 1,3-butanediol obtained in step (2) is distilled to obtain the anti-cracking agent composition.

[0057] According to the method described above, in the prepared anti-cracking agent composition, when the relative retention time of 1,3-butanediol is set to 1.0, the content of component II (residual impurity) corresponding to the peak appearing in the range of 1.1-1.3 with a relative retention time of 1.1-1.3 is in the range of 1-1000 ppm.

[0058] According to the method described above, the alkaline catalyst in step (1) may include, but is not limited to, one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, trimethylamine and triethylamine.

[0059] According to the method described above, the reaction temperature of the condensation reaction in step (1) is 0-30℃ (e.g., 2℃, 4℃, 5℃, 6℃, 8℃, 10℃, 12℃, 14℃, 15℃, 20℃, 22℃, 25℃, 28℃), preferably 5-15℃, and the reaction time can be 6-9h (e.g., 6.5h, 7h, 7.5h, 8h, 8.5h).

[0060] According to the method described above, the condensation process is carried out using a batch reactor or an external circulation reactor, and the mixing effect is strictly controlled, with a batch reactor being preferred. By controlling the stirring linear velocity of the stirrer at 3.36-12.67 m / s, preferably 6.18-9.62 m / s, a moderate reaction rate can be ensured, and the total conversion rate of 3-hydroxybutyraldehyde in the obtained product is greater than 99.9%. If an external circulation reactor is used, the same mixing effect as that of the batch reactor should be achieved.

[0061] According to the method described above, the hydrogenation catalyst used in step (2) can be one or more of Raney nickel, Raney cobalt, supported nickel, and supported cobalt catalysts. The preparation process of the hydrogenation catalyst can be carried out through conventional operations in the art, and will not be elaborated here. The content of each component in the hydrogenation catalyst can also be conventionally selected in the art. For example, the hydrogenation catalyst can also be obtained from commercially available products.

[0062] According to the method described above, the hydrogenation reaction in step (2) can be carried out using a fixed-bed reactor or a batch reactor.

[0063] According to the method described above, the process conditions for the hydrogenation reaction in step (2) include: a reaction temperature range of 80-180℃ (e.g., 90℃, 100℃, 120℃, 135℃, 145℃), preferably 100-160℃, more preferably 120-140℃; a pressure range of 2-20MPa (e.g., 3MPa, 4MPa, 4.5MPa, 5.5MPa, 6.5MPa, 7MPa, 8MPa, 10MPa, 15MPa, 18MPa), preferably 3-12MPa (gauge pressure); and a reaction space velocity of 0.05-0.5h. -1 (e.g., 0.06h) -1 0.1h -1 0.2h -1 0.25h -1 0.3h -1 0.35h -1 0.4h -1 0.45h -1 ).

[0064] According to the method described above, the distillation separation process in step (3) can be carried out using either batch distillation or continuous distillation. The equipment and distillation process conditions used in the distillation separation process can be conventional choices in the art. For example, the distillation equipment can be a packed column or a plate column, with the number of plates being, for example, 10-20 (e.g., 12, 14, 15, 18), and the operating pressure being, for example, 2-5 kPa (absolute pressure). The fraction at 102-110°C is collected by distillation to obtain the anti-cracking agent composition.

[0065] Through repeated verification, the inventors discovered that one of the reasons why 1,3-butanediol products prepared by existing methods affect the discharge performance of lithium batteries is that 1,3-butanediol products inevitably contain a certain amount of higher carbon chain chemicals. These chemicals (as impurities) are not easily volatile and have high chemical polarity. These impurities remaining in the negative electrode will affect the overall discharge performance of the lithium battery.

[0066] To address this issue, the inventors discovered through extensive research that when the relative retention time of 1,3-butanediol in 1,3-butanediol products (or anti-cracking agent compositions) is set to 1.0, the content of component II (residual impurity) corresponding to the peak appearing in the range of 1.1-1.3 relative retention time is controlled within the range of 1-1000 ppm. This can minimize the adverse effects of this residual impurity in 1,3-butanediol products on the overall charging and discharging performance of lithium batteries. This is likely because controlling the residual amount of this impurity below 1000 ppm keeps the resulting polarity accumulation within a controllable range, having little or no impact on battery charging and discharging. Detailed Implementation

[0067] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0068] Unless otherwise specified, the main raw materials and reagents involved in the following embodiments of the present invention were all purchased from commercially available sources.

[0069] Example of preparation of anti-cracking agent composition

[0070] The preparation steps of the anti-cracking agent composition are as follows:

[0071] (1) In a reactor, 50g of sodium hydroxide aqueous solution with a concentration of 1wt% was added dropwise to 500g of acetaldehyde feed (purity ≥99.5%) over a period of 4 hours. The condensation reaction temperature was controlled at 10-15℃ by a cold bath. After the addition was completed, the reaction continued for 3 hours. Then, acetic acid was added to the system to neutralize it until the system was neutral. The condensation reaction was carried out under stirring, and the stirring linear speed of Examples 1-6 was carried out according to the conditions shown in Table 1.

[0072] Then, unreacted acetaldehyde in the system is removed and recovered by short-path evaporation to obtain a condensate of 3-hydroxybutyraldehyde (i.e., hydrogenation feedstock solution);

[0073] (2) The Raney nickel hydrogenation catalyst (Raney 6800, purchased from GRACE) was loaded into two hydrogenation stationary reactors connected in series. 50 mL of the hydrogenation catalyst was loaded into each of the two hydrogenation stationary reactors, and the hydrogenation catalyst was activated with hydrogen at 2 MPa and 380 °C for 8 h. The temperature was then lowered to the reaction temperature and the pressure was adjusted to the reaction pressure.

[0074] Then, the condensate of 3-hydroxybutyraldehyde obtained in step (1) was diluted with ethanol by an equal mass to a concentration of 50 wt%, and continuously pumped into the hydrogenation stationary reactor at a reaction volume hourly space velocity of 0.2 h⁻¹. -1 The reaction pressure is 6 MPa (gauge pressure), and the reaction temperature is 130℃.

[0075] (3) The reaction solution containing 1,3-butanediol obtained in step (2) is separated by distillation. The distillation conditions are: 15 plates and 2.5 kPa (absolute pressure). The fraction at 106-107°C is collected to obtain the anti-cracking agent composition product (the products obtained in Examples 1-6 are numbered as anti-cracking agent composition 1# to anti-cracking agent composition 6#).

[0076] Comparative Example of Cracking Prevention Composition Preparation

[0077] The operation steps are as described in the above embodiments, except that: step (1) uses different stirring speeds for the condensation reaction, and the stirring speed conditions of Comparative Examples 1-3 are shown in Table 2; the remaining steps are the same as those in the embodiments (the products obtained from Comparative Examples 1-3 are numbered as anti-cracking agent composition 1'# to anti-cracking agent composition 3'#).

[0078] To evaluate the anti-cracking agent compositions obtained in each embodiment and comparative example, gas chromatography was used for analysis. The area fraction of 1,3-butanediol was read. If the relative retention time of 1,3-butanediol was set to 1.0, the area fraction of the components corresponding to the peaks appearing in the range of relative retention time 1.1-1.3 was read. Gas chromatography analysis conditions:

[0079] Chromatographic column: capillary column; column material: fused silica;

[0080] Model / Stationary Phase: Model number DB-5, stationary phase is (5% phenyl)-methylpolysiloxane;

[0081] Column length: 30m;

[0082] Column inner diameter: 0.32mm;

[0083] Liquid film thickness: 0.25 μm;

[0084] Column temperature: Initial temperature 50℃, hold for 2 min, then increase to 80℃ at 5℃ / min, then increase to 280℃ at 15℃ / min and hold for 15 min;

[0085] Carrier gas: Nitrogen;

[0086] Carrier gas flow rate: 1.5 mL / min (constant flow mode);

[0087] Vaporization chamber temperature: 270℃;

[0088] Detector temperature: 280℃;

[0089] Injection volume: 1.0 μL;

[0090] Flow split ratio: 10:1;

[0091] Airflow rate: 400 mL / min;

[0092] Hydrogen gas flow rate: 30 mL / min;

[0093] Purging flow rate: 25 mL / min;

[0094] Injected sample: 1 μL of acetonitrile solution containing 10% by weight of the sample.

[0095] In the anti-cracking agent compositions prepared in the various embodiments and comparative examples, if the relative retention time of 1,3-butanediol is set to 1.0, the peaks appearing in the range of 1.1-1.3 corresponding to component II are 3-methyl-2,4-pentanediol and / or its isomers.

[0096] After the anti-cracking agent compositions 1# to 6# prepared in each embodiment were analyzed by gas chromatography, the area ratio of component II corresponding to the peaks appearing in the range of relative retention time 1.1-1.3 is shown in Table 1.

[0097] Table 2 shows the area fraction of component II corresponding to the peaks appearing in the range of relative retention time 1.1-1.3 after gas chromatography analysis of the anti-cracking agent compositions 1'# to 3'# prepared in each comparative example.

[0098] Table 1. Some process parameters and test results of Examples 1-6

[0099] Table 2 shows some process parameters and test results for Comparative Examples 1-3.

[0100] Battery discharge performance evaluation

[0101] 1. Preparation process of lithium battery electrode (negative electrode):

[0102] (1) The anti-cracking agent compositions prepared in Examples 1-6 and Comparative Examples 1-3 were dissolved in water, and then sodium carboxymethyl cellulose as a binder was added and mixed evenly. Then, graphite as a negative electrode active material and conductive carbon black as a conductive agent were added and magnetically stirred for 5-6 hours to mix them evenly, forming negative electrode slurries with appropriate viscosity and uniform composition. The viscosity was 7000 mP·s and the solid content was 50 wt%. Based on the total weight of each component being 100 wt%, the amounts of negative electrode active material, conductive agent, binder and anti-cracking agent composition were 80 wt%, 13 wt%, 6 wt%, and 1 wt%, respectively.

[0103] (2) Using a glass rod, the negative electrode slurry prepared above is evenly coated onto the copper foil cleaned with anhydrous ethanol. After being labeled with serial numbers, it is transferred to an oven and vacuum dried at 100°C for 8 hours to obtain each group of electrode-copper foil.

[0104] (3) Place the electrode-copper foils prepared above in an oven and dry them at 100°C. Then take out the dried electrode-copper foils, place them flat on a roller press, adjust the roller spacing and roller pressure to compact the electrode sheets, and then use a button cell slicer to cut out several electrode sheets and store them in a vacuum drying oven.

[0105] 2. Battery assembly:

[0106] The battery was assembled in a glove box filled with inert gas. The assembly sequence was as follows: Place the positive electrode shell, then gently place the prepared electrode plates in the center of the positive electrode shell using tweezers. Add 1-3 drops of electrolyte on top, cover with the separator, and add another 1-3 drops of electrolyte. Next, place the lithium metal sheet, steel sheet, gasket, and negative electrode shell in sequence. Finally, seal the assembled battery using a button cell battery sealer, ensuring it is clean to prevent leakage. The positive electrode shell used for assembly was a CR2025 battery shell, the separator was a polytetrafluoroethylene microporous separator, and the electrolyte was a mixed solution of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate containing lithium salt LiPF6.

[0107] 3. Battery charge / discharge performance test:

[0108] The charge-discharge cycle performance test mainly includes the sum of cycle performance tests. A constant current charge-discharge rate of 0.2C was used, and the test conditions were room temperature (25℃). The voltage range was set to 0.01-3V, and the instrument used was a LAND CT2001A multi-channel battery tester. Cyclic voltammetry was used to test the change in discharge capacity during battery cycling to determine the cycle stability of the battery under test. This experiment tested the discharge capacity after 100 cycles. The test results are shown in Table 3.

[0109] Table 3 Battery performance test results

[0110] According to the test results in Tables 1-3 above, in the anti-cracking agent compositions prepared in each comparative example, the area fraction of the components corresponding to the peaks appearing in the relative retention time range of 1.1-1.3 is greater than 1000 ppm. This will have a significant adverse effect on the discharge capacity, charging capacity, and cycle discharge capacity of the lithium batteries prepared from it. In the anti-cracking agent compositions prepared in each embodiment of the present invention, the area fraction of the components corresponding to the peaks appearing in the relative retention time range of 1.1-1.3 is less than 1000 ppm, indicating that the content of impurities such as 3-methyl-2,4-pentanediol and / or its isomers in the anti-cracking agent compositions prepared in each embodiment is controlled within the range of 1-1000 ppm. When the anti-cracking agent compositions with this characteristic are applied to lithium batteries, the discharge capacity, charging capacity, and cycle discharge capacity are all significantly improved.

[0111] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A crack-resistant composition based on 1,3-butanediol, characterized in that, The crack-resistant agent composition includes: 1,3-butanediol as component I, and component II, which corresponds to the peak appearing in the range of 1.1-1.3 when the relative retention time of 1,3-butanediol is set to 1.0 under gas chromatography analysis; In the anti-cracking agent composition, the content of component II corresponding to the peak appearing in the range of relative retention time of 1.1-1.3 is 1-1000 ppm, preferably 1-200 ppm, more preferably 1-100 ppm; the balance is 1,3-butanediol.

2. The anti-cracking agent composition according to claim 1, characterized in that, When the relative retention time of 1,3-butanediol is set to 1.0 under gas chromatography, the structural formula of component II corresponding to the peaks appearing in the range of 1.1-1.3 relative retention time is C6H. 14 O2.

3. The anti-cracking agent composition according to claim 2, characterized in that, The peaks appearing in the range of 1.1-1.3 relative retention times correspond to component II, which is 3-methyl-2,4-pentanediol and / or its isomers.

4. The anti-cracking agent composition according to any one of claims 1-3, characterized in that, The conditions for the gas chromatography analysis include: Chromatographic column: capillary column; column material: fused silica; Model / Stationary Phase: Model number DB-5, stationary phase is (5% phenyl)-methylpolysiloxane; Column length: 30m; Column inner diameter: 0.32mm; Liquid film thickness: 0.25 μm; Column temperature: Initial temperature 50℃, hold for 2 min, then increase to 80℃ at 5℃ / min, then increase to 280℃ at 15℃ / min and hold for 15 min; Carrier gas: Nitrogen; Carrier gas flow rate: 1.5 mL / min (constant flow mode); Vaporization chamber temperature: 270℃; Detector temperature: 280℃; Injection volume: 1.0 μL; Flow split ratio: 10:1; Airflow rate: 400 mL / min; Hydrogen gas flow rate: 30 mL / min; Purging flow rate: 25 mL / min; Injected sample: 1 μL of acetonitrile solution containing 10% by weight of the sample.

5. The application of the anti-cracking agent composition according to any one of claims 1-4 in the negative electrode sheet of a lithium battery.

6. The application according to claim 5, characterized in that, The lithium battery negative electrode sheet is prepared by negative electrode slurry; The negative electrode slurry comprises: a negative electrode active material, a conductive agent, a binder, and the aforementioned anti-cracking agent composition.

7. The application according to claim 6, characterized in that, The preparation method of the negative electrode slurry includes the following steps: (1) Preparation of electrode dispersion: Mix water with the anti-cracking agent composition evenly to prepare an anti-cracking agent aqueous solution; (2) Preparation of water-based adhesive solution: Mix the anti-cracking agent aqueous solution obtained above with the adhesive evenly to prepare a water-based adhesive solution; (3) Preparation of slurry: Mix the negative electrode active material, conductive agent and the aqueous binder solution obtained above to form a uniform negative electrode slurry.

8. The application according to claim 6 or 7, characterized in that, In the negative electrode slurry, the amount of the anti-cracking agent composition is 0.1-2 wt% based on the total weight of all components.

9. The application according to any one of claims 6-8, characterized in that, In the negative electrode slurry, based on the total weight of all components: The amount of the negative electrode active material is 75-98 wt%. The amount of the conductive agent used is 1-20 wt%. The amount of the adhesive used is 1-10 wt%.

10. The application according to any one of claims 6-9, characterized in that, The negative electrode active material is selected from one or more of graphite, silicon, silicon oxide, and silicon carbon; The conductive agent is selected from one or more of carbon black, carbon nanotubes, graphene, and carbon fiber. The adhesive is selected from one or more of sodium carboxymethyl cellulose, styrene-butadiene latex, acrylamide adhesives, acrylonitrile adhesives, polyvinyl alcohol, and sodium alginate adhesives.

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