A modified acrylate polymer and its preparation method and application

Abstract

The present invention discloses a modified acrylate polymer, its preparation method, and application, belonging to the technical field of lithium-ion battery materials. The modified acrylate polymer provided by the present invention has a simple preparation method, is easy to synthesize, has a high reaction product yield, is low in preparation cost, and has excellent environmental performance. A lithium-ion battery separator coating prepared using the modified acrylate polymer provided by the present invention exhibits good electrolyte wetting properties, can reduce the battery's internal resistance, and improve the battery's rate performance and discharge capacity. It also exhibits good high-temperature resistance, which can enhance the safety and reliability of the battery in high-temperature environments or when overheated.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery materials, and more specifically, to a modified acrylate polymer and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries are important green energy sources. Due to their lightweight, high specific capacity, and safety, they have been widely used in mobile power supplies, laptops, mobile phones, electric vehicles, and other fields. Lithium-ion batteries are generally composed of packaging materials, positive and negative electrodes, separators, and electrolytes. The separator is a key material that separates the positive and negative electrodes in the battery core. During battery operation, lithium ions can freely pass through the separator to enable charging and discharging. The quality of the separator directly affects the battery's lifespan and safety.

[0003] The diaphragm materials used in commercial lithium-ion batteries are often mainly polyethylene and polypropylene. These materials have the disadvantage of poor temperature resistance, and as non-polar materials, they have poor electrolyte absorption and retention properties. Therefore, it is common to coat aramid, PVDF-HFP, inorganic coating materials, etc. on the diaphragm base film to improve the thermal stability, liquid absorption and retention of the diaphragm and the adhesion of the electrode, thereby improving battery safety, energy density, rate discharge, cycle life, etc. However, among the above coating materials, aramid-based special coating materials have the best high-temperature resistance, but are very expensive; PVDF-HFP has good electrolyte wettability and high-temperature resistance, but due to environmental reasons, its raw materials are strictly controlled and the price is also expensive; inorganic coating materials such as Al2O3 have cost advantages, but have problems such as easy powder shedding, pore clogging, and high density resulting in low battery energy density.

[0004] Existing polyacrylate materials, such as polymethyl methacrylate (PMMA), are low-priced and have good electrolyte wettability, but they are not resistant to high temperatures (PMMA's maximum continuous use temperature varies between 65°C and 95°C depending on working conditions, and its heat deformation temperature is approximately 96°C), making them unsuitable for direct use as battery separator coating materials.

[0005] Therefore, there is an urgent need to develop diaphragm coating materials that have both electrolyte wetting properties and high temperature resistance. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a modified acrylate polymer and its preparation method and application. The modified acrylate polymer of the present invention has both excellent high temperature resistance and good electrolyte infiltration performance, and can be used as a lithium ion battery separator coating material.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A modified acrylate polymer, the structure of which is shown in formula (1):

[0009]

[0010] Wherein, the main chain substituent R1 of the polymer is selected from C1-C 10 One of an alkyl group, a cyano group, a bromine group, a chlorine group, a phenyl group, a 2-naphthyl group and a hydrogen atom;

[0011] The side chain substituent R2 of the polymer is selected from one of cyano, bromine, chloride, methanesulfonyl, ethylsulfonyl, benzenesulfonyl, formyl, acetyl, benzoyl, phenyl, 2-naphthyl, 3-cyclopentanesulfonyl, 4-cyclopentanesulfonyl and hydrogen atom;

[0012] Optionally, the types of the main chain substituent R1 and the side chain substituent R2 of the polymer affect the mobility of the polymer molecules, and thus affect the mechanical strength and glass transition temperature of the polymer. Among them, the introduction of aromatic groups and polar groups will increase the glass transition temperature of the polymer, and the aromatic group can increase the rigidity of the molecular chain due to its rigidity and the presence of the π electron cloud, thereby increasing the glass transition temperature; the polar group further strengthens the interaction between molecules by forming hydrogen bonds or other strong dipole interactions, resulting in an increase in the glass transition temperature. In addition, the present invention further prefers the introduction of polar groups on the side chain substituent R2, especially sulfonyl, acyl or cyano groups, so that the wettability of the electrolyte to the acrylic polymer can be improved through the dipole effect;

[0013] Preferably, the main chain substituent R1 of the polymer is selected from one of C1-C3 alkyl, cyano, phenyl and 2-naphthyl.

[0014] Preferably, the side chain substituent R2 of the polymer is selected from one of cyano, methylsulfonyl, phenylsulfonyl, phenyl, 2-naphthyl, 3-cyclopentanesulfonyl or 4-cyclopentanesulfonyl.

[0015] Furthermore, the number x of methylene groups (CH2) in the side chain of the polymer is 0-10.

[0016] Optionally, the role of the side chain in the polymer is to link the ester functional group of the polyacrylate and the side chain substituent R2, wherein the number x of methylene groups (CH2) and the side chain substituent R2 can be further limited as follows: when the side chain substituent R2 is selected from phenyl, 2-naphthyl, 3-cyclobutylsulfone or 4-cyclopentylsulfone, x is 0 to 10; when the side chain substituent R2 is selected from cyano, bromine, chlorine, methylsulfonyl, ethylsulfonyl, phenylsulfonyl, formyl, acetyl, benzoyl or hydrogen atom, x is 1 to 10.

[0017] Optionally, the length of the methylene group (CH2) in the side chain of the polymer affects the mobility of the polymer side chain. The longer the side chain, the better the migration ability of the side chain and the lower the glass transition temperature.

[0018] Preferably, the number x of methylene groups (CH2) in the side chain of the polymer is 0-3.

[0019] Furthermore, the number n of repeating units in the polymer is 1000-5000.

[0020] Optionally, a larger value of the number n of repeating units in the polymer represents a higher molecular weight of the polymer. At this time, due to the enhanced interaction between long-chain molecules, the glass transition temperature of the material increases, the strength and toughness increase, and the mechanical properties of the polymer are improved.

[0021] Another object of the present invention is to provide a method for preparing the modified acrylate polymer, comprising the following steps:

[0022] (1) adding a substrate A represented by formula (2), a substrate B represented by formula (3) and a base into a solvent X for reaction, and then separating and purifying the obtained reaction product with an extractant to obtain a modified acrylate monomer represented by formula (4);

[0023]

[0024] (2) The modified acrylate monomer and the auxiliary agent are added to solvent Y for reaction, and then the obtained reaction product is separated and dried to obtain the modified acrylate polymer.

[0025] Wherein, R3 in formula (2) is selected from C1-C 10 wherein R4 in formula (3) is selected from one of cyano, bromine, chlorine, methanesulfonyl, ethylsulfonyl, benzenesulfonyl, formyl, acetyl, benzoyl, phenyl, 2-naphthyl, 3-cyclobutylsulfonyl, 4-cyclopentylsulfonyl and hydrogen atom; and the number x of methylene groups (CH2) in the side chain of substrate B is 0-10.

[0026] Preferably, R3 in formula (2) is selected from one of C1-C2 alkyl, cyano, phenyl or 2-naphthyl; preferably, R4 in formula (3) is selected from one of cyano, methylsulfonyl, ethylsulfonyl, phenylsulfonyl, phenyl, 2-naphthyl, 3-cyclobutylsulfonyl or 4-cyclopentylsulfonyl; preferably, the number x of side chain methylene groups (CH2) in substrate B is 0-3.

[0027] Optionally, in the preparation method of the polymer, the number x of substituent R3, substituent R4 and methylene (CH2) in the structure of substrate A and substrate B remains unchanged during the preparation process, which is consistent with the modified acrylate monomer shown in formula (4) and the modified acrylate polymer finally prepared.

[0028] Optionally, the base in step (1) is selected from one or a combination of two or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, triethylamine and 4-dimethylaminopyridine; preferably, the base in step (1) is triethylamine.

[0029] Optionally, the solvent X in step (1) is selected from one or a combination of two or more of dichloromethane, chloroform, toluene and N,N-dimethylformamide; preferably, the solvent X in step (1) is dichloromethane.

[0030] Optionally, the extractant in step (1) is selected from one or a combination of two or more of dichloromethane, chloroform, ethyl acetate and diethyl ether; preferably, the extractant in step (1) is dichloromethane.

[0031] Optionally, the auxiliary agent in step (2) is selected from one or a combination of two or more of azobisisobutyronitrile, azobisisoheptanenitrile and dibenzoyl peroxide; preferably, the auxiliary agent in step (2) is azobisisobutyronitrile.

[0032] Optionally, the solvent Y in step (2) is selected from one or a combination of two or more of N,N-dimethylformamide, methanol and acetone; preferably, the solvent Y in step (2) is N,N-dimethylformamide.

[0033] Optionally, the molar ratio of substrate A to substrate B in step (1) is 10:1 to 1:10; preferably, the molar ratio of substrate A to substrate B in step (1) is 2:1 to 1:2.

[0034] Optionally, the molar ratio of substrate A to base in step (1) is 1:1 to 1:10; preferably, the molar ratio of substrate A to base in step (1) is 1:1 to 1:2.

[0035] Optionally, the concentration of substrate A in solvent X in step (1) is 0.1 mol / L to 5.0 mol / L; preferably, the concentration of substrate A in solvent X in step (1) is 0.5 mol / L to 1.0 mol / L.

[0036] Optionally, the amount of the additive added in step (2) is 1 wt% to 10 wt% of the modified acrylate monomer; preferably, the amount of the additive added in step (2) is 2 wt% to 5 wt% of the modified acrylate monomer.

[0037] Optionally, the concentration of the modified acrylate monomer in the solvent Y in step (2) is 0.1 mol / L to 5.0 mol / L; preferably, the concentration of the modified acrylate monomer in the solvent Y in step (2) is 0.5 mol / L to 1.0 mol / L.

[0038] Optionally, the reaction temperature in step (1) is 0°C to 100°C; preferably, the reaction temperature in step (1) is 20°C to 50°C.

[0039] Optionally, the reaction time in step (1) is 8 h to 24 h; preferably, the reaction time in step (1) is 8 h to 12 h.

[0040] Optionally, the reaction temperature in step (2) is 0°C~100°C; preferably, the reaction temperature in step (2) is 60°C~80°C.

[0041] Optionally, the reaction time in step (2) is 8 h to 24 h; preferably, the reaction time in step (2) is 8 h to 12 h.

[0042] Optionally, the drying temperature in step (2) is 60°C to 150°C; preferably, the drying temperature in step (2) is 80°C to 100°C.

[0043] Optionally, the drying time in step (2) is 12 h to 96 h; preferably, the drying time in step (2) is 24 h to 72 h.

[0044] Another object of the present invention is to provide a modified acrylate polymer as described above, or a modified acrylate polymer prepared by the above preparation method, and use the modified acrylate polymer in a lithium-ion battery separator coating material.

[0045] Optionally, the preparation method of the lithium-ion battery separator includes the following steps: using the modified acrylate polymer as described above to prepare a lithium-ion battery separator coating material, and coating it on both sides of a commercial polyolefin separator by electrospinning, and then hot pressing to form a double-sided coating-modified lithium-ion battery separator.

[0046] Optionally, the specific preparation steps are as follows:

[0047] (1) The modified acrylate polymer is added to N,N-dimethylformamide and stirred to dissolve to obtain an electrospinning solution.

[0048] (2) The electrospinning solution is added to a syringe, and a commercial diaphragm is placed on a receiving roller for electrospinning. The composite membrane is collected, and then the collected composite membrane is placed in a vacuum drying oven and treated at room temperature under reduced pressure until no solvent remains.

[0049] (3) The dried membrane with the modified coating on one side is placed on the receiving roller again, with the unspun side exposed, and electrospinning is performed again at an appropriate voltage, receiving distance and extrusion speed. The composite membrane is collected and then placed in a vacuum drying oven at room temperature and reduced pressure until no solvent remains.

[0050] (4) The dried composite film was subjected to five hot roller pressing and one hot pressing treatment to obtain a coating-modified lithium-ion battery separator.

[0051] Compared with the prior art, the modified acrylic polymer provided by the present invention and its preparation and application have the following beneficial effects:

[0052] (1) The modified acrylate polymer provided by the present invention has a simple preparation method, is easy to synthesize, has a high reaction product yield, has a low preparation cost, and has excellent environmental performance and both excellent high temperature resistance and good electrolyte infiltration performance.

[0053] (2) The lithium-ion battery separator coating prepared using the modified acrylate polymer provided by the present invention has good electrolyte infiltration performance, can reduce the internal resistance of the battery, and improve the battery's rate performance and discharge capacity.

[0054] (3) The lithium-ion battery separator coating prepared using the modified acrylate polymer provided by the present invention has good high-temperature resistance and can improve the safety and reliability of the battery in a high-temperature environment or when overheated. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is the morphology of the composite diaphragm modified with the A-1-9 coating material prepared in Example 10 of the present invention. DETAILED DESCRIPTION

[0056] In order to further illustrate the present invention, the following examples are listed based on experimental results, but they do not limit the scope of the invention defined by the claims of the present invention.

[0057] Example 1

[0058] This example illustrates the preparation of poly (2-cyano)ethyl methacrylate.

[0059] The preparation method of the modified acrylate polymer of this embodiment comprises the following steps:

[0060] (1) Dissolve 40 mmol of methacryloyl chloride, 20 mmol of cyanoethanol, and 80 mmol of triethylamine (Et3N) in 80 mL of dichloromethane (CH2Cl2), and then stir the mixture at 20 °C for 12 h.

[0061] (2) After the reaction is completed, water is added to quench the reaction, and then the product is extracted with dichloromethane. The solvent is then evaporated to obtain the polymer monomer.

[0062] (3) The polymer monomer prepared in step (2) and azobisisobutyronitrile (AIBN) were dissolved in 80 mL of N,N-dimethylformamide (DMF), and then stirred at 60 °C for 12 h, wherein the amount of azobisisobutyronitrile added was 2 wt% of the modified acrylate monomer.

[0063] (4) The solid product was separated and dried at 80 °C for 72 h to obtain poly(2-cyano)ethyl methacrylate, designated as A-1-1, with a reaction yield of 82%.

[0064] The reaction scheme of the modified acrylate polymer of the present embodiment is as follows:

[0065]

[0066] Example 2

[0067] This example illustrates the effect of different substrate concentrations on the preparation of poly (2-cyano)ethyl methacrylate.

[0068] The only difference between this embodiment and embodiment 1 is that the amount of dichloromethane added in step (1) is set to 8 mL, 40 mL, and 400 mL, respectively. The rest is the same as in embodiment 1.

[0069] The yields of the polymers prepared under different substrate concentration conditions were analyzed, and the results are shown in Table 1.

[0070] Table 1 Effect of different substrate concentrations on the preparation of poly (2-cyano)ethyl methacrylate

[0071]

[0072] Example 3

[0073] This example illustrates the effect of different molar ratios of substrate A to substrate B on the preparation of poly (2-cyano)ethyl methacrylate.

[0074] The only difference between this embodiment and embodiment 1 is that the amount of cyanoethanol added in step (1) is set to 4 mmol, 80 mmol, and 400 mmol, respectively. The rest is the same as in embodiment 1.

[0075] The yields of the polymers prepared under different molar ratios of substrate A to substrate B were analyzed, and the results are shown in Table 2.

[0076] Table 2 Effect of different molar ratios of substrate A to substrate B on the preparation of poly (2-cyano)ethyl methacrylate

[0077]

[0078] Example 4

[0079] This example illustrates the effect of different molar ratios of substrate A to base on the preparation of poly (2-cyano)ethyl methacrylate.

[0080] The only difference between this embodiment and embodiment 1 is that the amount of triethylamine added in step (1) is set to 40 mmol and 400 mmol respectively, and the rest is the same as embodiment 1.

[0081] The yields of the polymers prepared under different molar ratios of substrate A to base were analyzed, and the results are shown in Table 3.

[0082] Table 3 Effect of triethylamine amount on the preparation of poly(2-cyano)ethyl methacrylate

[0083]

[0084] Example 5

[0085] This example illustrates the effect of different esterification reaction temperatures on the preparation of poly (2-cyano)ethyl methacrylate.

[0086] The only difference between this embodiment and embodiment 1 is that the reaction temperature in step (1) is set to 10°C, 30°C, and 100°C, respectively. The rest is the same as embodiment 1.

[0087] The yields of the polymers prepared under different esterification reaction temperature conditions were analyzed, and the results are shown in Table 4.

[0088] Table 4 Effect of different esterification reaction temperatures on the preparation of poly (2-cyano)ethyl methacrylate

[0089]

[0090] Example 6

[0091] This example illustrates the effect of different additive amounts on the preparation of poly(2-cyano)ethyl methacrylate.

[0092] The only difference between this embodiment and embodiment 1 is that the addition amount of azobisisobutyronitrile in step (3) is set to 1 wt%, 3 wt%, and 10 wt% of the modified acrylate monomer, respectively. The rest is the same as in embodiment 1.

[0093] The yields of the polymers prepared under different additive addition conditions were analyzed, and the results are shown in Table 5.

[0094] Table 5 Effect of the mass ratio of azobisisobutyronitrile to monomer on the preparation of poly(2-cyano)ethyl methacrylate

[0095]

[0096] Example 7

[0097] This example illustrates the effect of different polymerization temperatures on the preparation of poly (2-cyano)ethyl methacrylate.

[0098] The only difference between this embodiment and embodiment 1 is that the polymerization reaction temperature in step (3) is set to 50°C, 80°C, and 100°C, respectively. The rest is the same as embodiment 1.

[0099] The yields of the polymers prepared under different polymerization reaction temperature conditions were analyzed, and the results are shown in Table 6.

[0100] Table 6 Effect of polymerization temperature on the preparation of poly (2-cyano)ethyl methacrylate

[0101]

[0102] Example 8

[0103] This example illustrates the effect of different substrates B on the preparation of poly (2-cyano)ethyl methacrylate.

[0104] Except for using a different type of substrate B instead of the cyanoethanol used in step (1) of Example 1, the rest is the same as Example 1.

[0105] Modified polyacrylates were prepared according to the method of Example 1. The yields of polymers prepared from different substrates B were analyzed. The results are shown in Table 7.

[0106] Table 7 Labeling and yield of different substrates B and the corresponding polymers

[0107]

[0108] Example 9

[0109] This example illustrates the effect of different substrates A on the preparation of poly (2-cyano)ethyl methacrylate.

[0110] The reaction was the same as in Example 1 except that a different type of substrate A was used instead of methacryloyl chloride used in step (1) of Example 1, and 20 mmol of 3-hydroxycyclopentane sulfone was used instead of 20 mmol of cyanoethanol used in step a).

[0111] Modified polyacrylates were prepared according to the method of Example 1. The yields of polymers prepared from different substrates A were analyzed, and the results are shown in Table 8.

[0112] Table 8 Labeling and yield of different substrates A and the corresponding polymers

[0113]

[0114] Example 10

[0115] This example illustrates the use of the modified polyacrylates prepared in Example 8 and Example 9 to modify the coating of a lithium-ion battery separator. The specific steps are as follows:

[0116] a) The modified polyacrylates prepared in Example 8 and Example 9 were respectively added to N,N-dimethylformamide and stirred for dissolution for 12 h to obtain electrospinning solutions.

[0117] b) The electrospinning solution was added to a syringe, and a commercial diaphragm was placed on a receiving roller. Electrospinning was performed at an 18 kV voltage, a 20 cm receiving distance, and a 20 mm stroke. The composite membrane was collected and then placed in a vacuum drying oven at room temperature under reduced pressure until no solvent remained.

[0118] c) The dried diaphragm with the modified coating on one side is again placed on the receiving roller, with the unspun side exposed, and electrospinning is performed again at an appropriate voltage, receiving distance, and extrusion speed. The composite membrane is collected and then placed in a vacuum drying oven at room temperature and reduced pressure until no solvent remains.

[0119] d) The dried composite film is subjected to five hot roller pressing processes and one hot pressing process to obtain a coating-modified lithium-ion battery separator.

[0120] Figure 1 This is the morphology of the composite diaphragm modified with A-1-9 as the coating material in this example.

[0121] Example 11

[0122] This example illustrates the liquid absorption and liquid retention performance tests of the lithium-ion battery separator containing the modified polyacrylate coating prepared in Example 10.

[0123] The test method for the liquid absorption rate of the coating-modified lithium-ion battery separator is as follows:

[0124] The coated lithium-ion battery separator was immersed in an electrolyte (LiPF6 = 1.0 mol / L, organic solvent of EC / DEC / DMC = 1 / 1 / 1) for 1 h, and then taken out and weighed to record the mass after immersion, where:

[0125] Liquid absorption rate (%) = (mass after immersion - mass before immersion) / mass before immersion * 100%

[0126] The test method for the liquid retention rate of the coating-modified lithium-ion battery separator is as follows:

[0127] The coating-modified lithium-ion battery separator was immersed in the electrolyte for 1 hour, and the excess electrolyte on the surface was absorbed by non-woven fabric and weighed as the retained electrolyte mass, where:

[0128] Liquid retention rate (%) = (liquid retention mass - mass before immersion) / mass before immersion * 100%

[0129] The test results of liquid absorption and liquid retention performance are summarized as follows:

[0130] Table 9 Test results of liquid absorption and liquid retention performance

[0131]

[0132] Example 12

[0133] In this example, the temperature resistance of the lithium-ion battery separator containing the modified polyacrylate coating prepared in Example 10 was tested.

[0134] The temperature resistance of the coating-modified lithium-ion battery separator was tested by a thermal shrinkage experiment, where:

[0135] Shrinkage rate (%) = diaphragm length after heat treatment / diaphragm length before heat treatment * 100%

[0136] The results of the thermal shrinkage experiments are summarized as follows:

[0137] Table 10 Temperature resistance test

[0138]

[0139] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a lithium ion battery separator, characterized in that: include: A lithium-ion battery separator coating material is prepared using a modified acrylic polymer, and is coated on both sides of a commercial polyolefin separator by electrospinning. After hot pressing and shaping, a double-sided coating-modified lithium-ion battery separator is obtained. The structure of the polymer is shown in formula (1): Wherein, when the main chain substituent R1 of the polymer is methyl, the side chain substituent R2 of the polymer is phenyl, 2-naphthyl, 3-cyclobutylsulfone or 4-cyclopentylsulfone, and the number x of methylene groups (CH2) in the side chain of the polymer is 0; When the main chain substituent R1 of the polymer is ethyl, cyano, phenyl, 2-naphthyl, bromine or chlorine, the side chain substituent R2 of the polymer is 3-cyclobutane sulfone, and the number x of methylene (CH2) groups in the side chain of the polymer is 0; The number n of repeating units in the polymer is 1000 to 5000; The preparation method of the modified acrylate polymer comprises the following steps: (1) adding a substrate A represented by formula (2), a substrate B represented by formula (3) and a base into a solvent X for reaction, and then separating and purifying the obtained reaction product with an extractant to obtain a modified acrylate monomer represented by formula (4); (2) adding the modified acrylate monomer and the auxiliary agent into solvent Y for reaction, and then separating and drying the obtained reaction product to obtain the modified acrylate polymer; In the step (1), the molar ratio of substrate A to substrate B is 2:1 to 1:10; the molar ratio of substrate A to base is 1:2 to 1:10; In the step (2), the amount of the additive added is 2 wt% to 10 wt% of the modified acrylate monomer; In the step (1), the reaction temperature is 20°C to 50°C; In the step (2), the reaction temperature is 50°C to 80°C; When R3 in formula (2) is selected from methyl, R4 in formula (3) is selected from phenyl, 2-naphthyl, 3-cyclobutylsulfone or 4-cyclopentylsulfone; the number x of methylene groups (CH2) in the side chain of substrate B is 0; When R3 in formula (2) is selected from ethyl, cyano, phenyl, 2-naphthyl, bromine or chlorine, R4 in formula (3) is selected from 3-cyclobutane sulfone; and the number x of methylene groups (CH2) in the side chain of substrate B is 0.

2. The method for preparing a lithium ion battery separator according to claim 1, wherein In the step (1), the base is selected from one or a combination of two or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, triethylamine and 4-dimethylaminopyridine; Solvent X is selected from one or a combination of two or more of dichloromethane, chloroform, toluene and N,N-dimethylformamide; The extractant is selected from one or a combination of two or more of dichloromethane, chloroform, ethyl acetate and ether.

3. The method for preparing a lithium ion battery separator according to claim 1, wherein: In the step (2), the auxiliary agent is selected from one or a combination of two or more of azobisisobutyronitrile, azobisisoheptanenitrile and dibenzoyl peroxide; The solvent Y is selected from one or a combination of two or more of N,N-dimethylformamide, methanol and acetone.

4. The method for preparing a lithium ion battery separator according to claim 1, wherein: In the step (1), the concentration of substrate A in solvent X is 0.1 mol / L to 5.0 mol / L.

5. The method for preparing a lithium ion battery separator according to claim 1, wherein: In the step (2), the concentration of the modified acrylate monomer in the solvent Y is 0.1 mol / L to 5.0 mol / L.

6. The method for preparing a lithium ion battery separator according to claim 1, wherein: In the step (1), the reaction time is 8 h to 24 h.

7. The method for preparing a lithium ion battery separator according to claim 1, wherein: In the step (2), the reaction time is 8 h to 24 h; the drying temperature is 60°C to 150°C; and the drying time is 12 h to 96 h.

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