Polymer-modified organic lithium-ion battery separator, and preparation method and application thereof

Abstract

This invention discloses a polymer-modified organic lithium-ion battery separator, its preparation method, and its application. The lithium-ion battery separator includes a base film and a coating on the base film. The coating includes a modified organic binder, a first auxiliary agent, and a second auxiliary agent. The first auxiliary agent is polymethylsiloxane, and the second auxiliary agent is sodium carboxymethyl cellulose. The preparation method of the modified organic binder includes mixing polyhydroxyimide, vinylidene fluoride copolymer, and a chain extender, and polymerizing them under stirring conditions to obtain the modified organic binder. This invention obtains the modified organic binder through the polymerization reaction of vinylidene fluoride copolymer and polyhydroxyimide. The polyhydroxyimide contains an aromatic ring rigid backbone, which enhances the heat resistance of the lithium-ion battery separator. The trifluoromethyl group increases the breakdown voltage of the separator. The main chain of the modified organic binder provides excellent adhesion performance, and the hydroxyl groups in the side chain further enhance the adhesion of the separator.

Description

Technical Field

[0001] This invention belongs to the field of battery separator technology, specifically relating to a polymer-modified organic lithium-ion battery separator, its preparation method, and its application. Background Technology

[0002] The separator is one of the core components of a lithium-ion battery, and its performance has a crucial impact on the overall performance of the battery. It is also one of the important factors restricting the development of high-performance lithium-ion battery technology. The rapid advancement of battery technology in new energy vehicles has placed higher demands on the heat resistance and adhesion performance of ultra-thin separators. Currently, aqueous ceramic coatings are applied to at least one side of a polyethylene-based membrane by blending polymeric binders and ceramic particles in a slurry. After drying, a rigid inorganic coating layer is formed on the surface of the base membrane, which can help inhibit separator shrinkage to some extent. However, the existing ceramic-coated separators have limited high-temperature resistance and cannot simultaneously achieve both high-temperature resistance and adhesion performance. Even increasing the ratio of polymeric binders to ceramic particles in the slurry does not significantly improve high-temperature resistance, and the ceramic separator does not have sufficient adhesion to the electrode. Given the limited heat resistance of current aqueous ceramic coatings, there is an urgent need to develop a separator with excellent heat resistance and adhesion performance. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a lithium-ion battery separator.

[0004] Another object of the present invention is to provide a method for preparing a modified organic adhesive.

[0005] Another object of the present invention is to provide a slurry.

[0006] The objective of this invention is achieved through the following technical solution.

[0007] A lithium-ion battery separator includes: a base film and a coating on the base film. The coating includes: a modified organic binder, a first additive, and a second additive. The first additive is polymethylsiloxane, and the second additive is sodium carboxymethyl cellulose. The ratio of the modified organic binder, the first additive, and the second additive by mass is 1:(0.01-0.05):(1-2). The structural formula of the modified organic binder is:

[0008] ,

[0009] The degree of polymerization, n3, is 1430–1455.

[0010] In the above technical solution, the number-average molecular weight of the modified organic adhesive is 1.18 to 1.2 million.

[0011] The method for preparing the above-mentioned lithium-ion battery separator includes: coating a slurry onto a base film, drying it, obtaining a coating on the base film, and obtaining a lithium-ion battery separator.

[0012] In the above technical solution, the coating method is either spot coating or roller coating.

[0013] In the above technical solution, the thickness of the coating is 1 to 10 μm.

[0014] A method for preparing a modified organic adhesive includes: mixing polyhydroxyimide, vinylidene fluoride copolymer and chain extender, and polymerizing them at -5 to 0°C for 2 to 10 hours under stirring conditions to obtain the modified organic adhesive, wherein the ratio of polyhydroxyimide, vinylidene fluoride copolymer and chain extender by molar amount is (0.1 to 0.2): 1: 0.05.

[0015] In the above technical solution, the chain extender is one or a mixture of dicyclohexylcarbodiimide (DCC), N,N-diisopropylcarbodiimide (DIC), carbodiimide hydrochloride (EDC), and 4-dimethylaminopyridine (DMAP).

[0016] In the above technical solution, the number average molecular weight of polyhydroxyimide is 29670-32260, and the degree of polymerization (n1) is 56-62.

[0017] In the above technical solution, the number average molecular weight of the vinylidene fluoride copolymer is 985,000 to 996,000, and the degree of polymerization (n2) is 2,943 to 2,977. The vinylidene fluoride copolymer is copolymerized from vinylidene fluoride, hexafluoropropylene and acrylic acid.

[0018] In the above technical solution, the modified organic adhesive is obtained by polymerization reaction at -5 to 0℃ for 2 to 10 hours under stirring conditions of 40 to 45 r / min.

[0019] In the above technical solution, the method for preparing polyhydroxyimide is as follows: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), terephthaloyl chloride (TPC) and a first solvent are mixed and reacted at -5 to 0°C for 3 to 6 hours under stirring conditions to obtain polyhydroxyimide. The ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to terephthaloyl chloride (TPC) is 1:(1 to 1.05) by weight.

[0020] In the method for preparing polyhydroxyimide, the reaction is carried out at -5 to 0°C for 3 to 6 hours under stirring conditions at a speed of 40 to 45 r / min.

[0021] In the method for preparing polyhydroxyimide, the molar ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to the volume fraction of the first solvent is (0.1–0.12):120, where the molar ratio is in mol and the volume fraction is in mL.

[0022] In the method for preparing polyhydroxyimide, the first solvent is at least one selected from N,N-dimethylacetamide (DMAC) (water content ≤2000ppm), N-methylpyrrolidone (NMP) (water content ≤2000ppm), hexamethylphosphoramide (HMPA) (water content ≤2000ppm), 1,4-dioxane (DOX) (water content ≤2000ppm), diethylene glycol dimethyl ether (DGDE) (water content ≤2000ppm), and N,N-dimethylformamide (DMF) (water content ≤2000ppm).

[0023] In the above technical solution, the method for preparing vinylidene fluoride copolymer is as follows: vinylidene fluoride, hexafluoropropylene, acrylic acid, initiator and second solvent are mixed and reacted at 120-130℃ for 10-12h under stirring conditions, cooled to -5-0℃, acyl chloride reagent is added, heated to 50-55℃ and refluxed at 50-55℃ for 6-8h to obtain vinylidene fluoride copolymer. The ratio of vinylidene fluoride, hexafluoropropylene, acrylic acid, initiator and acyl chloride reagent by molar amount is 1:0.3:(0.1-0.2):0.001:10.

[0024] In the method for preparing vinylidene fluoride copolymers, the acyl chloride reagent is thionyl chloride.

[0025] In the method for preparing vinylidene fluoride copolymer, the initiator is tert-butyl peroxyvalerate, and the second solvent is acetonitrile (water content ≤2000ppm).

[0026] In the method for preparing vinylidene fluoride copolymer, the ratio of the molar amount of vinylidene fluoride to the volume amount of the second solvent is 1:(500-510), where the molar amount is in mol and the volume amount is in mL.

[0027] In the method for preparing vinylidene fluoride copolymer, the reaction is carried out at 120-130°C for 10-12 h under stirring conditions at a speed of 40-45 r / min.

[0028] A slurry comprising: a modified organic binder, a first additive, and a second additive, wherein the ratio of the modified organic binder, the first additive, and the second additive by mass parts is 1:(0.01-0.05):(1-2).

[0029] The method for preparing the above-mentioned slurry includes: mixing the modified organic adhesive, the first additive, and the second additive until homogeneous to obtain the slurry.

[0030] In the above technical solution, the modified organic binder, the first additive, and the second additive are mixed and stirred at a dispersion speed of 1200-2000 r / min and a stirring speed of 20-40 r / min for 1-2 hours until uniform, to obtain a slurry.

[0031] The application of modified organic adhesives in improving the heat resistance of diaphragms; the structural formula of the modified organic adhesive is as follows: ,

[0032] The degree of polymerization, n3, is 1430–1455.

[0033] The application of modified organic adhesives in improving diaphragm adhesion; the structural formula of the modified organic adhesive is as follows: ,

[0034] The degree of polymerization, n3, is 1430–1455.

[0035] The modified organic binder of this invention comprises vinylidene fluoride segments, hexafluoropropylene segments, and acrylic acid segments in its main chain, and imide segments in its side chains. In its structural design, it not only focuses on the selection and ratio of monomers but also emphasizes the synergistic effect between the main chain and side chains. This results in a lithium-ion battery separator that possesses both high heat resistance and excellent adhesion performance. The high heat resistance is attributed to the presence of fluorinated components in the main chain and the addition of side chains. The excellent adhesion strength is due to the acrylic acid segments, as part of the main chain, which impart good adhesive force to the lithium-ion battery separator. The lithium-ion battery separator of this invention maintains stable physicochemical properties under extreme high-temperature conditions and is not easily decomposed or degraded.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention prepares a modified organic adhesive through polymer polymerization: a modified organic adhesive is obtained by polymerizing vinylidene fluoride copolymer and polyhydroxyimide. The polyhydroxyimide contains a rigid aromatic ring backbone. The introduction of the rigid aromatic ring backbone enhances the heat resistance of the lithium-ion battery separator. The trifluoromethyl group reduces the molar polarizability α of the lithium-ion battery separator, resulting in lower dielectric constant and dielectric loss, and consequently, higher breakdown voltage. The main chain of the modified organic adhesive provides excellent adhesion, and the hydroxyl groups in the side chains can form intermolecular hydrogen bonds to further enhance the adhesion of the lithium-ion battery separator, thereby increasing the adhesive strength. The slurry of this invention can be prepared without adding water. Attached Figure Description

[0038] Figure 1The reaction formula for synthesizing polyhydroxyimide;

[0039] Figure 2 The reaction formula for synthesizing vinylidene fluoride copolymer;

[0040] Figure 3 The reaction formula for synthesizing modified organic adhesives;

[0041] Figure 4 The ATR spectrum of the modified organic adhesive;

[0042] Figure 5 The image shows a SEM image of the membrane prepared in Example 5. Detailed Implementation

[0043] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0044] Shrinkage rate was tested according to GB / T 36363-2018.

[0045] The breakdown voltage was tested in accordance with GB-T 13542.2-2009.

[0046] Hot-pressed positive electrode bonding strength: The separator and positive electrode are cut to a size of 25*150mm and 25*150mm respectively. The temperature of the hot press is set to 80℃ and the pressure to 1000KG. The separator and positive electrode are preheated for 1 second and then hot-pressed for 1 second. The bonding strength of the hot-pressed positive electrode is tested using an electronic tensile testing machine. The separator and positive electrode are peeled until the tensile distance of the electronic tensile testing machine is 50mm. The speed of the electronic tensile testing machine is 300mm / min and the peel angle is 180°. The bonding strength of the hot-pressed positive electrode is calculated as the peel force divided by the tensile distance of the electronic tensile testing machine. The peel force is the average value of the force collected by the electronic tensile testing machine during the peeling process of the separator and positive electrode. The bonding strength of the hot-pressed positive electrode is calculated based on the data between 10 and 40mm, that is, the bonding strength of the hot-pressed positive electrode is calculated as the peel force between 10 and 40mm divided by 30mm. The positive electrode is a ternary lithium nickel cobalt aluminum oxide (LiNi) 0.8 Co 0.15 Al 0.05 O2) electrode.

[0047] Hot-pressed negative electrode bonding strength: The test method is basically the same as that for "hot-pressed positive electrode bonding strength", except that "positive electrode" is replaced with "negative electrode", and the negative electrode is a carbon-based graphite electrode (containing 91% carbon).

[0048] In the following examples, the base film is a wet-process polyethylene film with a thickness of 7.1 μm (it should be noted that other thicknesses can also be used) and an air permeability of 71 Sec / 100 ml. The thickness in this patent is tested in accordance with GBT 36363—2018.

[0049] The raw material information involved in the following examples is as follows:

[0050] Polymethylsiloxane: a colorless, transparent liquid with a number-average molecular weight of 19,823 and a density of 0.965 g / cm³. 3 Fuchen Chemical Reagent Co., Ltd.

[0051] Sodium carboxymethyl cellulose: a light yellow powder with a viscosity of 400-800 cP (2% solubility in water at 25℃ test), manufactured by Shanghai Pudong New Area Bide Pharmaceutical Co., Ltd.

[0052] 4-Dimethylaminopyridine (DMAP): C7H 10 N2, with a molecular weight of 122.17 g / mol, is a white powder with a melting point of 109℃, a boiling point of 211℃, and a density of 1.0 g / cm³. 3 (25℃), flash point is 110℃, Shanghai Pudong New Area Bide Pharmaceutical Co., Ltd.

[0053] 2,2-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP): White powder, molecular formula C 15 H 12 F6N2O2 has a molecular weight of 366.26. It has a melting point of 245℃, a boiling point of approximately 411.3℃, a flash point of 202.6℃, and a density of 1.545 g / cm³. 3 (25℃), 98% purity, Bailingwei Technology Co., Ltd.

[0054] Terephthaloyl chloride (TPC): Molecular formula C8H4Cl2O2, molecular weight 203.0 g / mol, colorless transparent crystalline powder, melting point 79℃, boiling point 266℃, density 1.34 g / cm³. 3 (25℃), purity 96%, Tianjin Guangfu Fine Chemical Research Institute.

[0055] Vinylidene fluoride (VDF): The molecular weight of VDF is 64.0341 g / mol. Its molecular formula is C₂H₂F₂, melting point is -144℃, and boiling point is -83℃. The flash point of VDF is below -60℃. Tianjin Jiangtian Chemical Co., Ltd.

[0056] Hexafluoropropylene: Chemical formula: C3F6. Molecular weight: 150.023. Density: 1.583 g / cm³ 3 (Liquid). Melting point: -153℃. Boiling point: -28℃. Tianjin Jiangtian Chemical Co., Ltd.

[0057] Acrylic acid: Shanghai Aladdin Reagent. Molecular weight: 72.06. Colorless liquid with a pungent odor. Melting point: 13℃. Boiling point: 140.9℃. Relative density: 1.051 g / cm³. 3 (Water = 1). Flash point: 54℃.

[0058] tert-butyl peroxyvalerate: Röhn's reagent, chemical formula: C9H 18 O3. Molecular weight: 174.237. Tert-butyl peroxyvalerate is a colorless liquid at room temperature. Density: 0.854 g / cm³. 3 (25℃). The melting point of tert-butyl peroxyvalerate is -17℃. The boiling point of tert-butyl peroxyvalerate is 182.5℃. The flash point is 68℃.

[0059] Thionyl chloride: Fuchen Chemical Reagent Co., Ltd. The molecular formula of thionyl chloride is SOCl2, and its relative molecular mass is 118.97. Thionyl chloride is a pale yellow liquid. Its melting point is -105℃, boiling point is 78.8℃, and density is 1.638 g / cm³. 3 (25℃).

[0060] Example 1

[0061] A method for preparing a slurry includes: mixing a modified organic binder, a first additive, and a second additive, and stirring at a dispersion speed of 2000 r / min (rotation) and a stirring speed of 40 r / min (revolution) for 2 hours until homogeneous, to obtain a slurry. The first additive is polymethylsiloxane, and the second additive is sodium carboxymethyl cellulose. The ratio of the modified organic binder, the first additive, and the second additive by mass is 1:0.05:2.

[0062] The method for preparing the modified organic adhesive includes: pumping the polyhydroxyimide (number average molecular weight of 32260) obtained in the second polymerization reactor and the vinylidene fluoride copolymer (number average molecular weight of 996,000) obtained in the first polymerization reactor into the third polymerization reactor via a bottom diaphragm pump; adding a chain extender; and reacting at -5°C for 10 hours under stirring at 40 r / min to obtain the modified organic adhesive. The ratio of polyhydroxyimide, vinylidene fluoride copolymer, and chain extender by molar amount is 0.1:1:0.05, and the chain extender is 4-dimethylaminopyridine (DMAP).

[0063] The method for preparing polyhydroxyimide is as follows: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), terephthaloyl chloride (TPC), and a first solvent are added to a second polymerization reactor and reacted at -5°C for 6 hours under stirring at 45 r / min to obtain polyhydroxyimide. The molar ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to terephthaloyl chloride (TPC) is 1:1.05, and the molar ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to the volume ratio of the first solvent is 0.12:120. The unit of molar ratio is mol, and the unit of volume ratio is ml. The first solvent is NMP (water content 1800 ppm).

[0064] The method for preparing vinylidene fluoride copolymer is as follows: vinylidene fluoride, hexafluoropropylene, acrylic acid, initiator, and second solvent are added to a first polymerization reactor for copolymerization. The reaction is carried out at 130℃ for 12 hours under stirring at 45 r / min. After 12 hours, the first polymerization reactor is cooled to -5℃, an acyl chloride reagent is added, and the mixture is heated to 50℃ and refluxed at 50℃ for 6 hours to obtain the vinylidene fluoride copolymer. The ratio of vinylidene fluoride, hexafluoropropylene, acrylic acid, initiator, and acyl chloride reagent by molar amount is 1:0.3:0.2:0.001:10. The acyl chloride reagent is thionyl chloride (molecular weight 118.97), the initiator is tert-butyl peroxyvalerate, and the second solvent is acetonitrile (water content 1800 ppm). The molar amount of vinylidene fluoride and the volume amount of the second solvent are 1:500. The unit of molar amount is mol, and the unit of volume amount is ml.

[0065] The number-average molecular weight of the modified organic adhesive prepared in Example 1 was 1.2 million.

[0066] Example 2

[0067] A method for preparing a slurry is basically the same as in Example 1, except that the phrase "by mass parts, the ratio of modified organic binder, first additive and second additive is 1:0.05:2" is replaced with "by mass parts, the ratio of modified organic binder, first additive and second additive is 1:0.01:1".

[0068] Example 3

[0069] A method for preparing a slurry is basically the same as that in Example 1, except that the polyhydroxyimide is different. Example 3 describes the preparation of polyhydroxyimide as follows: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), terephthaloyl chloride (TPC), and a first solvent were added to a second polymerization reactor and reacted at -5°C for 3 hours under stirring at 40 r / min to obtain polyhydroxyimide (number average molecular weight 30561). The ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to terephthaloyl chloride (TPC) was 1:1, and the ratio of the molar amount of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to the volume amount of the first solvent was 0.10:120. The unit of molar amount is mol, and the unit of volume amount is ml. The first solvent was DMF (water content 1800 ppm).

[0070] The number-average molecular weight of the modified organic adhesive prepared in Example 3 was 1.18 million.

[0071] Example 4

[0072] A method for preparing a slurry is basically the same as that in Example 1, except that the vinylidene fluoride copolymer is different. Example 4 describes the preparation of vinylidene fluoride copolymers as follows: Vinylidene fluoride, hexafluoropropylene, acrylic acid, an initiator, and a second solvent were added to a first polymerization reactor for copolymerization. The reaction was carried out at 120°C for 10 hours under stirring at 40 r / min. After 10 hours, the first polymerization reactor was cooled to 0°C, an acyl chloride reagent was added, and the mixture was heated to 50°C and refluxed at 50°C for 6 hours to obtain a vinylidene fluoride copolymer (number average molecular weight of 990,000). The ratio of vinylidene fluoride, hexafluoropropylene, acrylic acid, initiator, and acyl chloride reagent by molar amount was 1:0.3:0.1:0.001:10. The acyl chloride reagent was thionyl chloride (molecular weight of 118.97), the initiator was tert-butyl peroxyvalerate, and the second solvent was acetonitrile (water content 1800 ppm). The molar amount of vinylidene fluoride and the volume amount of the second solvent were 1:500. The unit of molar amount is mol, and the unit of volume amount is ml.

[0073] The number-average molecular weight of the modified organic adhesive prepared in Example 4 was 1.19 million.

[0074] Example 5

[0075] A method for preparing a lithium-ion battery separator includes: pumping the slurry prepared in Example 1 into a dot-coating structure via a slurry pump, coating it on both sides of a base film, drying it at 80°C for 10 min, and obtaining a coating on the base film to obtain a lithium-ion battery separator. The coating dots are circular with a diameter of 400 μm, and the coating dots are arranged in a square with a side length of 500 μm.

[0076] Example 6

[0077] A method for preparing a lithium-ion battery separator includes: pumping the slurry prepared in Example 1 into a grooved roller coating structure (grooved roller depth is 5μm) through a slurry pump, coating it on both sides of a base film, drying it at 80°C for 10min, and obtaining a coating on the base film to obtain a lithium-ion battery separator.

[0078] Example 7

[0079] A method for preparing a lithium-ion battery separator is basically the same as that in Example 5, except that "the slurry prepared in Example 1" is replaced with "the slurry prepared in Example 2".

[0080] Example 8

[0081] A method for preparing a lithium-ion battery separator is basically the same as that in Example 5, except that "the slurry prepared in Example 1" is replaced with "the slurry prepared in Example 3".

[0082] Example 9

[0083] A method for preparing a lithium-ion battery separator is basically the same as that in Example 5, except that "the slurry prepared in Example 1" is replaced with "the slurry prepared in Example 4".

[0084] Comparative Example 1

[0085] A method for preparing a lithium-ion battery separator is basically the same as that in Example 5, except that the slurry used is different.

[0086] The method for preparing the slurry in Comparative Example 1 includes: mixing water, PVDF powder (purchased from Sinochem Lantian Fluorine Materials Co., Ltd., the PVDF powder is a copolymer of vinylidene fluoride and hexafluoropropylene, melting point 1151℃, particle size D50=6μm), a first additive and a second additive, and stirring at a dispersion speed of 2000r / min and a stirring speed of 40r / min for 2h until uniform to obtain the slurry. The first additive is polymethylsiloxane, and the second additive is sodium carboxymethyl cellulose. By mass parts, the ratio of water, PVDF powder, first additive and second additive is 10:1:0.05:2.

[0087] Comparative Example 2

[0088] A method for preparing a lithium-ion battery separator is basically the same as that in Example 6, except that "the slurry prepared in Example 1" is replaced with "the slurry prepared in Comparative Example 1".

[0089] Comparative Example 3

[0090] A method for preparing a lithium-ion battery separator is basically the same as that in Example 5, except that the modified organic binder used in the slurry is different. The number average molecular weight of the modified organic binder in Comparative Example 3 is 830,000.

[0091] The method for preparing the modified organic adhesive in Comparative Example 3 includes: mixing polyhydroxyimide, vinylidene fluoride copolymer (the same as the vinylidene fluoride copolymer in Example 1), and 4-dimethylaminopyridine (DMAP), and reacting at 0°C for 10 h under stirring at 40 r / min to obtain the modified organic adhesive of Comparative Example 3. The ratio of polyhydroxyimide, vinylidene fluoride copolymer, and 4-dimethylaminopyridine (DMAP) by molar ratio is 0.1:1:0.05. The method for preparing the polyhydroxyimide is as follows: mixing 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), terephthaloyl chloride (TPC), and... The first solvent was added to the polymerization reactor, and the reaction was carried out at 25°C for 1 hour under stirring at 20 r / min to obtain polyhydroxyimide (number average molecular weight of 19149). The ratio of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to terephthaloyl chloride (TPC) was 1:0.9 by molar amount, and the ratio of the molar amount of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to the volume amount of the first solvent was 0.12:120. The unit of molar amount is mol, and the unit of volume amount is ml. The first solvent was NMP (water content 1800 ppm).

[0092] The single-sided coating amount of the lithium-ion battery separators prepared in Examples 5-9 and Comparative Examples 1-3 was 0.9 g / m².

[0093] Table 1

[0094]

[0095]

[0096] Figure 1 The reaction formula for synthesizing polyhydroxyimide; Figure 2 The reaction formula for synthesizing vinylidene fluoride copolymer; Figure 3 The reaction formula for synthesizing modified organic adhesives; Figure 4 The ATR spectrum of the modified organic adhesive is shown in the image. Figure 43093-2850cm -1 There is an absorption peak for the stretching vibration of OH at 1747 cm⁻¹. -1 and 1598cm -1 There are absorption peaks at 3425 cm⁻¹ for the C=O stretching vibration of the amide bond and the bending vibration of NH. -1 It has an absorption peak at NH stretching vibration, 1396 cm⁻¹. -1 It exhibits CN stretching vibration, 1178cm -1 The presence of a CF stretching vibration peak indicates the successful synthesis of the target modified organic adhesive.

[0097] Figure 5 The image shows a SEM image of the membrane prepared in Example 5.

[0098] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A modified organic adhesive, characterized in that, The structural formula of the modified organic adhesive is: ， The degree of polymerization, n3, is 1430–1455.

2. A method for preparing a modified organic adhesive, characterized in that, include: Polyhydroxyimide, vinylidene fluoride copolymer and chain extender are mixed and polymerized at -5 to 0°C for 2 to 10 hours under stirring to obtain modified organic adhesive. The ratio of polyhydroxyimide, vinylidene fluoride copolymer and chain extender by weight is (0.1 to 0.2): 1: 0.

05. The structural formula of polyhydroxyimide is: The degree of polymerization, n1, is 56–62. The structural formula of vinylidene fluoride copolymer is: The degree of polymerization n2 is 2943–2977.

3. A lithium-ion battery separator, characterized in that, include: The base film and the coating on the base film, the coating comprising: a modified organic adhesive, a first auxiliary agent and a second auxiliary agent, wherein the first auxiliary agent is polymethylsiloxane and the second auxiliary agent is sodium carboxymethyl cellulose, and the ratio of the modified organic adhesive, the first auxiliary agent and the second auxiliary agent by mass parts is 1:(0.01-0.05):(1-2), wherein the modified organic adhesive is one of the modified organic adhesives obtained by the preparation method described in claims 1 and 2.

4. The lithium-ion battery separator according to claim 3, characterized in that, The thickness of the coating is 1 to 10 μm.

5. A method for preparing the lithium-ion battery separator according to claim 4, characterized in that, include: The slurry is coated onto the base film and dried to obtain a coating on the base film, thus obtaining a lithium-ion battery separator.

6. A slurry, characterized in that, include: The modified organic adhesive, the first additive, and the second additive are in a ratio of 1:(0.01-0.05):(1-2) by mass parts, and the modified organic adhesive is one of the modified organic adhesives obtained by the preparation methods described in claims 1 and 2.

7. A method for preparing the slurry according to claim 6, characterized in that, include: The modified organic binder, the first additive, and the second additive are mixed until homogeneous to obtain a slurry.

8. The application of modified organic adhesives in improving the heat resistance and / or adhesion of diaphragms, characterized in that, The modified organic adhesive is one of the modified organic adhesives obtained by the preparation methods described in claims 1 and 2.

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