Battery separator coating process and battery separator prepared thereby

Abstract

A battery separator coating process and a battery separator prepared thereby, relating to the technical field of battery separators. The battery separator coating process comprises the following steps: providing a coating, the coating comprising 35-45 parts by weight of polyvinylidene fluoride micro powder, 15-25 parts by weight of fluorine-silicon modified polyurethane, 4.8-5.8 parts by weight of nano aluminum oxide, 1-2 parts by weight of a wetting agent, 0.2-0.3 parts by weight of a thickening agent, 0.1-0.15 parts by weight of a dispersing agent and 40 parts by weight of a solvent; coating a base film with a dot coating: coating the surface of the base film with the coating by using a flexographic printing process, and on a continuous winding belt, drying at 110-120℃ for 1-2 s and drying at 60-80℃ for 10-15 s. By using the process above, the base film is coated with the dot coating, so that stable coating of the dot coating having a dot diameter of 0.01 mm and an inter-dot spacing of 0.01 mm can be achieved, thereby obtaining a battery separator having high electrode sheet bonding performance, high air permeability and long service life.

Description

A battery separator coating process and battery separator prepared therefrom Technical Field

[0001] The present application relates to the technical field of lithium battery separators, and in particular to a battery separator coating process and a battery separator produced therefrom, which can be applied to the new energy industry. Background Art

[0002] Lithium batteries are widely used in various fields due to their excellent electrochemical performance and environmentally friendly, pollution-free nature. The separator is a crucial component of lithium-ion batteries, primarily blocking the transfer of electrons between the positive and negative electrodes to prevent short circuits while allowing lithium ions to pass between the positive and negative electrodes, enabling the battery to function properly.

[0003] To improve the thermal stability of lithium-ion battery separators, a coating is typically applied to the surface of the base membrane. To ensure good air permeability, the coating is typically spot-coated. Spot coating is typically achieved by applying an alumina ceramic coating to the base membrane surface using gravure roller coating technology and then drying it.

[0004] Patent application CN109301139A discloses a polymer-coated separator for lithium-ion batteries. The separator comprises a base film and a polymer distributed on the base film. The polymer distribution pattern includes intermittently distributed protrusions and sporadically distributed small dots. Because the protrusions in this polymer-coated separator are around tens of microns in size, similar to the particle size of the positive and negative electrodes, the resulting lithium-ion battery is virtually immune to lithium deposition.

[0005] Patent application number CN114039170A discloses a PVDF-coated separator, a coating method, and batteries and objects using the same, relating to the field of secondary battery technology. The PVDF-coated separator comprises a porous base membrane and a PVDF coating applied to at least one surface of the base membrane. The coating is uniformly distributed in a dot-like pattern and applied using a dot-coating gravure roller. This dot-coating PVDF coating improves the permeability of the separator, effectively reducing resistance to lithium ion transport within the battery and improving the battery's charge and discharge performance.

[0006] Among them, in the above-mentioned related technologies, the coating of the diaphragm is all carried out by gravure roller coating technology, and the coating is all carried out by PVDF dot coating without aluminum oxide. However, in order to improve the thermal stability of the diaphragm, aluminum oxide ceramic particles are usually added. The aluminum oxide ceramic particles have high hardness. During the coating process, the anilox roller of the gravure roller coating is prone to wear, resulting in that it is difficult to control the distance between the points covered on the diaphragm, the size of the points, or the morphology of the points during the production process. In addition, when the distance between the points of the current dot coating is not less than 0.1mm, if it is less than, adhesion is likely to occur between the points, resulting in changes in the distance between the points and the size and morphology of the points, and when the diameter of the dot coating is not less than 0.1mm, if it is less than, the coating of the dot coating is prone to incomplete problems, which is also likely to cause changes in the distance between the points, the size and morphology of the points.

[0007] In summary, the existing battery separator coating process produces a problem of poor morphological stability of the dot coating. The morphology of the dot coating also affects the battery separator's air permeability, thermal stability, and adhesion to the electrode, ultimately affecting the stability of the battery's service life.

[0008] Summary of the Invention

[0009] In order to improve the problem of poor point coating morphology stability during the coating process of the battery separator coating in the related art, the present application provides a battery separator coating process and a battery separator produced therefrom.

[0010] In the first aspect, the present application provides a battery separator coating process using the following technical solutions:

[0011] A battery separator coating process comprises the following steps:

[0012] Providing a coating, which comprises, based on raw materials, 35-45 parts by weight of polyvinylidene fluoride powder, 15-25 parts by weight of fluorosilicone modified polyurethane, 4.8-5.8 parts by weight of nano-alumina, 1-2 parts by weight of a wetting agent, 0.2-0.3 parts by weight of a thickener, 0.1-0.15 parts by weight of a dispersant, and 40 parts by weight of a solvent;

[0013] The base film is dot-coated by applying the coating on the surface of the base film using a flexographic printing process, and drying the coating on a continuous roll at 110-120° C. for 1-2 seconds and then at 60-80° C. for 10-15 seconds to complete the dot coating on the surface of the base film;

[0014] Wherein, the flexible printing plate used in the flexographic printing process is provided with a dot coating pattern, and the dot coating pattern is a plurality of concave dots or convex dots arranged at intervals.

[0015] Preferably, the diameter of the concave or convex point is 0.01 mm, the spacing between two adjacent concave points or two adjacent convex points or between adjacent concave points and convex points is 0.01 mm, and when the diameter of the concave or convex point is 0.01 mm, and / or the spacing between two adjacent concave points or two adjacent convex points or between adjacent concave points and convex points is 0.01 mm, the dot coating layer will not have any missing dots, and the dots are separated from each other without adhesion.

[0016] The diameter of the concave or convex point includes 0.01 mm, but is not limited to 0.01 mm. The diameter of the concave or convex point can also be 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, etc.

[0017] The spacing between two adjacent concave points or two adjacent convex points or between adjacent concave points and convex points includes 0.01mm, but is not limited to 0.01mm. The spacing between two adjacent concave points or two adjacent convex points or between adjacent concave points and convex points can also be 0.05mm, 0.1mm, 0.15mm, 0.2mm, etc.

[0018] By adopting the above technical solution, the present application uses heat-resistant polyvinylidene fluoride micropowder and fluorine-silicon modified polyurethane as the film-forming materials of the dot coating, and adds heat-resistant and high-hardness nano-aluminum oxide, which can improve the heat resistance, adhesion and wettability of the dot coating, and has a promoting effect on improving the heat resistance of the diaphragm and the adhesion between the diaphragm and the electrode. Secondly, by adding a wetting agent, a thickener and a dispersant within the above-mentioned ratio range, the dispersibility of the coating can be improved, and the wettability of the dot coating can be further improved. Even when the diameter of the dot in the dot coating is 0.01mm, there will be no omission of the dot, which is conducive to ensuring the morphological stability of the dot coating after coating. At the same time, the coating has moderate fluidity, and combined with the two-step drying of high temperature and then low temperature of the present application, even when the spacing between the dots in the dot coating is 0.01mm, there is no adhesion between the dots, and the morphology of the dot coating is stable. In addition, the present application adopts flexographic printing technology instead of the traditional commonly used gravure printing technology. Since the printing plate used in flexographic printing is a flexible printing plate, the flexible printing plate usually uses a photosensitive resin or photosensitive rubber with good elasticity. During the coating process, the flexible printing plate has good pressure resistance, wear resistance and good resilience. The flexible printing plate can be continuously processed for a long time, which can not only achieve efficient coating, but also facilitate the stable coating of the point coating.

[0019] In general, this application uses the above-mentioned process to apply dot coating to the base film, which can achieve stable coating of dot coating with a dot diameter of 0.01mm and a spacing between dots of 0.01mm, which is conducive to obtaining a battery separator with strong bonding performance with the electrode, high air permeability, good thermal stability and long service life.

[0020] Preferably, the solvent is green and environmentally friendly water.

[0021] Preferably, based on the raw materials, the fluorosilicone modified polyurethane includes polyether diol, diisocyanate, tetrafluorophenylenediol, dihydroxy-terminated polydimethylsiloxane, a catalyst, a chain extender and water, and the weight ratio of the polyether diol, diisocyanate, tetrafluorophenylenediol, dihydroxy-terminated polydimethylsiloxane, the catalyst, the chain extender and the water is (44-52): (30-35): (5.5-8.5): (10-15): (0.005-0.01): (2-4): 50.

[0022] By adopting the above technical solution, in this application, tetrafluorophenylenedimethanol is used to introduce fluorine groups into polyurethane, and double-terminal hydroxyl polydimethylsiloxane is used to introduce organic siloxane segments into polyurethane, thereby obtaining fluorine-silicon modified polyurethane. x Compared with the introduction of fluorinated diols by CH2OH, the introduction of fluorinated groups into polyurethane by using tetrafluorophenylenediol can simultaneously introduce heat-resistant phenyl groups, which is beneficial to further improve the heat resistance of the spot coating on the battery separator and further improve the service life of the battery separator.

[0023] Optionally, the polyether diol is at least one of polytetramethylene glycol and polyoxypropylene glycol.

[0024] Optionally, the diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0025] Optionally, the catalyst is at least one of bismuth isooctanoate and dibutyltin dilaurate. Optionally, the chain extender is at least one of ethylenediamine, 1,4-butanediol, and glycerol.

[0026] Preferably, the providing of the coating comprises the following preparatory steps:

[0027] After removing water from the polyether diol, heat it to 45-55°C, then add diisocyanate, tetrafluorophenylenediol, dihydroxy-terminated polydimethylsiloxane and catalyst, stir evenly, heat it to 75-85°C, and react for 3-4 hours to obtain a prepolymer;

[0028] Add a chain extender to the prepolymer and continue the reaction for 1-2 hours. Finally, add water and stir evenly to obtain fluorosilicone modified polyurethane.

[0029] By adopting the above technical solution, the above method for preparing fluorosilicone modified polyurethane has the advantages of simple steps and convenient operation.

[0030] Preferably, the wetting agent is a polyether-modified silicone wetting agent.

[0031] In this application, compared with fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether, the wetting agent used is a polyether-modified silicone wetting agent, which can reduce the thickness of the spot coating, improve the air permeability of the diaphragm, and ensure the adhesion between the diaphragm and the electrode.

[0032] Preferably, the diameter of the concave or convex point is 0.01-0.05 mm, and the distance between two adjacent concave points or two adjacent convex points or between an adjacent concave point and a convex point is 0.01-0.1 mm.

[0033] In this application, when the diameter of the concave or convex points of the dot coating pattern on the flexible printing plate is controlled at 0.01-0.05mm and the distance between the points is controlled at 0.01-0.1mm, the diaphragm can have the advantages of good air permeability and good bonding stability with the pole piece. Among them, the air permeability of the diaphragm can affect the charge and discharge performance and safety performance of the battery. Good air permeability can quickly dissipate the heat generated by the battery operation, thereby preventing high temperature from affecting the charge and discharge of the battery. In addition, the dot coating with a small dot diameter and a small distance between the dots can further reduce the thermal deformation caused by the thermal expansion and contraction of the diaphragm, so that the diaphragm can still maintain stable performance in a high temperature environment, and the battery is not prone to lithium plating, which can increase the stability and electrical performance of the battery using the diaphragm.

[0034] Preferably, the thickness of the dot coating is 0.3-0.5 μm.

[0035] In the present application, when the wetting agent is a polyether-modified silicone wetting agent, the wetting effect of the coating on the diaphragm and the electrode is further enhanced. When the thickness of the dot coating is controlled at 0.3-0.5 μm, the diaphragm and the electrode can maintain good bonding strength. At the same time, when the thickness of the dot coating is controlled at 0.3-0.5 μm, the air permeability of the diaphragm can be further improved, which is beneficial to increase the stability and electrical performance of the battery using the diaphragm.

[0036] Optionally, the base film is made of at least one of a polyolefin film and a polyimide film.

[0037] Preferably, the base film has a thickness of 16-30 μm and a porosity of 40-60%.

[0038] In the present application, the base film preferably has a thickness of 16-30 μm and a porosity of 40-60%, so that the separator has good air permeability.

[0039] Optionally, the thickener is at least one of hydroxyethyl cellulose, methyl hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, and sodium alginate.

[0040] Optionally, the dispersant is at least one of sodium polyacrylate and ammonium polyacrylate.

[0041] In a second aspect, the present application provides a battery separator, which is produced by any one of the above battery separator coating processes.

[0042] In summary, this application includes at least one of the following beneficial technical effects:

[0043] (1) This application uses heat-resistant polyvinylidene fluoride micropowder and fluorine-silicon modified polyurethane as the film-forming materials of the dot coating, and adds heat-resistant and high-hardness nano-aluminum oxide. At the same time, a wetting agent, a thickener, and a dispersant within the above-mentioned ratio range are added. Even when the diameter of the dot coating is 0.01mm, the dots will not be missed, which is conducive to ensuring the morphological stability of the dot coating after coating. At the same time, the coating has moderate fluidity. Combined with the two-step drying of high temperature and then low temperature of this application, even when the spacing between dots in the dot coating is 0.01mm, there is no adhesion between the dots, and the morphology of the dot coating is stable.

[0044] (2) Compared with fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether, the wetting agent uses a polyether-modified silicone wetting agent, which can reduce the thickness of the point coating, improve the air permeability of the diaphragm, and ensure the adhesion between the diaphragm and the electrode, which is beneficial to extending the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a schematic diagram of the arrangement of dot coating patterns on a flexible printing plate used in various embodiments and comparative examples of the present application.

[0046] FIG2 is a partially enlarged view of the battery separator prepared in Example 1 of the present application (the battery separators of Examples 2 and 7 are similar to that of Example 1).

[0047] Explanation of the accompanying drawings: 1. Flexographic printing plate; 2. Dot coating pattern. DETAILED DESCRIPTION

[0048] The present application is further described below in conjunction with Examples 1-7 and Comparative Examples 1-3. In each of the Examples and Comparative Examples, the base film is a polyethylene film with a thickness of 16 μm and a porosity of 45%. The bihydroxylated polydimethylsiloxane has a molecular weight of 1000. The polyvinylidene fluoride powder used in the coating has a molecular weight of 400,000-450,000 and a particle size of 800-1000 mesh.

[0049] Example

[0050] [Example 1]

[0051] A battery separator coating process comprises the following steps:

[0052] S1. Provide coating;

[0053] S11, after removing water from 44 kg of polytetramethylene ether glycol with a molecular weight of 2000, heating to 45° C., then adding 30 kg of isophorone diisocyanate, 8.5 kg of tetrafluorophenylenediol, 15 kg of double-terminated hydroxyl polydimethylsiloxane and 0.005 kg of dibutyltin dilaurate, stirring evenly, heating to 75° C., and reacting for 4 hours to obtain a prepolymer;

[0054] S12, adding 2 kg of ethylenediamine to the prepolymer, continuing the reaction for 1 hour, and finally adding 50 kg of water and stirring evenly to obtain fluorosilicone-modified polyurethane;

[0055] S13, 35 kg of polyvinylidene fluoride powder, 25 kg of fluorosilicone modified polyurethane, 4.8 kg of nano-alumina, 1 kg of fatty alcohol polyoxyethylene ether, 0.2 kg of sodium carboxymethyl cellulose, 0.1 kg of sodium polyacrylate and 40 kg of water were uniformly mixed to prepare a coating;

[0056] S2: Dot coating of the base film: The coating is applied to the base film surface using a flexographic printing process. The coating is dried on a continuous web at 110°C for 2 seconds and then at 80°C for 10 seconds. The dot coating is completed. The dry film thickness of the dot coating is controlled to 1μm. The flexographic printing plate 1 used in the flexographic printing process is provided with a dot coating pattern 2, which consists of a number of spaced-apart raised dots (as shown in Figure 1). The diameter of the dots is 0.01mm, and the spacing between adjacent dots is 0.01mm.

[0057] [Example 2]

[0058] A battery separator coating process comprises the following steps:

[0059] S1. Provide coating;

[0060] S11, after removing water from 52 kg of polytetramethylene ether glycol with a molecular weight of 1800, heating to 55° C., then adding 35 kg of diphenylmethane diisocyanate, 5.5 kg of tetrafluorophenylenediol, 10 kg of double-terminated hydroxyl polydimethylsiloxane and 0.01 kg of dibutyltin dilaurate, stirring evenly, heating to 85° C., and reacting for 3 hours to obtain a prepolymer;

[0061] S12, adding 4 kg of 1,4-butanediol to the prepolymer, continuing the reaction for 2 h, and finally adding 50 kg of water and stirring evenly to obtain fluorosilicone-modified polyurethane;

[0062] S13, 45 kg of polyvinylidene fluoride powder, 15 kg of fluorosilicone modified polyurethane, 5.8 kg of nano-alumina, 2 kg of fatty alcohol polyoxyethylene ether, 0.3 kg of carboxymethyl cellulose, 0.15 kg of ammonium polyacrylate and 40 kg of water were uniformly mixed to prepare a coating;

[0063] S2. Dot coating of the base film: The coating is applied to the base film surface using a flexographic printing process. The coating is dried on a continuous web at 120°C for 1 second and then at 60°C for 15 seconds. The dot coating is completed on the base film surface. The dry film thickness of the dot coating is controlled to be 1 μm. The flexographic printing plate 1 used in the flexographic printing process is provided with a dot coating pattern 2, which consists of a plurality of spaced concave dots (as shown in Figure 1). The diameter of the concave dots is 0.05 mm, and the spacing between adjacent concave dots is 0.025 mm.

[0064] [Example 3]

[0065] A battery separator coating process, which differs from [Example 1] in that:

[0066] In step S2, the dry film thickness of the dot coating is controlled to be 0.3 μm.

[0067] [Example 4]

[0068] A battery separator coating process, which differs from [Example 3] in that:

[0069] In step S13, an equal amount of polyether-modified silicone Hydropalat WE3220 is used to replace fatty alcohol polyoxyethylene ether.

[0070] [Example 5]

[0071] A battery separator coating process, which differs from [Example 3] in that:

[0072] In step S13, an equal amount of polyether-modified silicone ECO-3270 is used to replace fatty alcohol polyoxyethylene ether.

[0073] [Example 6]

[0074] A battery separator coating process, which differs from [Example 3] in that:

[0075] In step S13, an equal amount of polyether-modified silicone Hydropalat WE3221 is used to replace fatty alcohol polyoxyethylene ether.

[0076] [Example 7]

[0077] A battery separator coating process, which differs from [Example 3] in that:

[0078] In step S13, an equal amount of alkylphenol polyoxyethylene ether is used instead of fatty alcohol polyoxyethylene ether.

[0079] Comparative Example

[0080] [Comparative Example 1]

[0081] A battery separator coating process, which differs from [Example 1] in that:

[0082] Steps S11 and S12 are omitted, and an equal amount of polyvinylidene fluoride micropowder is used instead of fluorine-silicon modified polyurethane.

[0083] [Comparative Example 2]

[0084] A battery separator coating process, which differs from [Example 1] in that:

[0085] In step S13, an equal amount of fluorosilicone-modified polyurethane is used instead of polyvinylidene fluoride powder.

[0086] [Comparative Example 3]

[0087] A battery separator coating process, which differs from [Example 1] in that:

[0088] In step S2, the first drying temperature is 80° C. and the drying time is 10 s, and the second drying temperature is 110° C. and the drying time is 2 s.

[0089] Performance testing

[0090] The battery separators prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to the following performance tests:

[0091] (1) Coating quality: Five diaphragms from each embodiment and comparative example were randomly selected after coating. After the diaphragms were magnified 10,000 times, the coating on the diaphragms was observed to see if there were any problems with missing coating or adhesion, and the results were recorded in Table 1 below.

[0092] (2) Air permeability: The time required for 100 mL of air to pass through a 1 square inch membrane was measured using a Gurley air permeability tester (Gurley-4110N) at a pressure of 1.22 kPa. The test temperature was room temperature.

[0093] (3) Positive electrode adhesion: The separators obtained after coating of the examples and comparative examples were assembled into lithium-ion batteries. After being fully soaked in electrolyte, the peel strength between the positive electrode sheet and the battery separator was tested.

[0094] (4) Heat shrinkage: The test was conducted in accordance with GB / T 13519-2016 “Polyethylene heat-shrinkable film for packaging”. The test temperature was 130°C and the test time was 30 min. The length shrinkage of the diaphragm before and after heat treatment was calculated.

[0095] (5) 500-cycle capacity retention: Coin cells were assembled using the separators prepared in each of the Examples and Comparative Examples with a ternary lithium cathode and a graphite anode. The electrolyte was a lithium hexafluorophosphate solution. The cells were subjected to charge and discharge cycles at a voltage of 4.0 V. Cycle capacity retention = 500-cycle discharge capacity / first-cycle discharge capacity * 100%.

[0096] Table 1

[0097] Table 2

[0098] The difference between Example 1 and Comparative Examples 1-2 lies in the different film-forming materials used in the coatings. Compared to Example 1, Comparative Example 1 uses polyvinylidene fluoride powder alone as the film-forming material, while Comparative Example 2 uses fluorine-silicon-modified polyurethane alone as the film-forming material. As shown in the data in Tables 1-2, when the dot coatings on the separators in Comparative Examples 1 and 2 have a dot diameter of 0.01 mm and a dot spacing of 0.01 mm, while there is no adhesion between the dots in the dot coatings, some individual dots suffer from coating omissions. This affects the air permeability and thermal stability of the coated separators, as well as the adhesion between the separators and the electrode plates. This results in a decrease in the capacity retention rate after 500 cycles, which is not conducive to extending the battery's service life.

[0099] The difference between Example 1 and Comparative Example 3 lies in the different coating drying conditions. Compared with Example 1, Comparative Example 3 uses a method of first drying the dot coating at low temperature and then drying it at high temperature. As shown in Table 1-2, in Comparative Example 3, when the dot coating on the separator has a dot diameter of 0.01 mm and a dot spacing of 0.01 mm, the dots in the dot coating are prone to adhesion. While this maintains the separator's heat resistance and the adhesion between the separator and the electrode, it significantly reduces the separator's air permeability, which is not conducive to improving the battery's service life.

[0100] The difference between Example 1 and Examples 3-7 lies in the coating thickness and / or wetting agent. Combined with the data in Tables 1-2, it can be seen that, compared with wetting agents using fatty alcohol polyoxyethylene ethers or alkylphenol polyoxyethylene ethers, using polyether-modified silicone wetting agents can reduce the coating thickness, improve the membrane's air permeability, and maintain adhesion between the membrane and the electrode. Furthermore, the thermal stability of the membrane is similar, and the battery has a high capacity retention rate after 500 cycles, which is beneficial for extending the battery's service life.

[0101] The examples of this specific embodiment are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A battery separator coating process, characterized in that: The following steps are involved: Providing a coating, which comprises, based on raw materials, 35-45 parts by weight of polyvinylidene fluoride powder, 15-25 parts by weight of fluorosilicone modified polyurethane, 4.8-5.8 parts by weight of nano-alumina, 1-2 parts by weight of a wetting agent, 0.2-0.3 parts by weight of a thickener, 0.1-0.15 parts by weight of a dispersant, and 40 parts by weight of a solvent; The base film is dot-coated, and the coating is applied to the surface of the base film using a flexographic printing process, and is first dried at 110-120° C. for 1-2 seconds and then dried at 60-80° C. for 10-15 seconds on a continuous roll to complete the dot coating on the surface of the base film; wherein the flexible printing plate used in the flexographic printing process is provided with a dot coating pattern, and the dot coating pattern is a plurality of concave or convex dots arranged at intervals.

2. The battery separator coating process according to claim 1, characterized in that: Calculated on the basis of raw materials, the fluorosilicone modified polyurethane includes polyether diol, diisocyanate, tetrafluorophenylenediol, dihydroxylated polydimethylsiloxane, a catalyst, a chain extender and water. The weight ratio of the polyether diol, diisocyanate, tetrafluorophenylenediol, dihydroxylated polydimethylsiloxane, the catalyst, the chain extender and the water is (44-52): (30-35): (5.5-8.5): (10-15): (0.005-0.01): (2-4):

50.

3. The battery separator coating process according to claim 2, characterized in that: The coating is provided comprising the following preparatory steps: After removing water from the polyether diol, heat it to 45-55°C, then add diisocyanate, tetrafluorophenylenediol, dihydroxy-terminated polydimethylsiloxane and catalyst, stir evenly, heat it to 75-85°C, and react for 3-4 hours to obtain a prepolymer; Add a chain extender to the prepolymer and continue the reaction for 1-2 hours. Finally, add water and stir evenly to obtain fluorosilicone modified polyurethane.

4. The battery separator coating process according to any one of claims 1 to 3, characterized in that: The wetting agent is a polyether-modified organic silicon wetting agent.

5. The battery separator coating process according to claim 4, characterized in that: The diameter of the concave or convex point is 0.01-0.05 mm, and the distance between two adjacent concave points or two adjacent convex points or between an adjacent concave point and a convex point is 0.01-0.1 mm.

6. The battery separator coating process according to claim 4, characterized in that: The thickness of the dot coating is 0.3-0.5 μm.

7. The battery separator coating process according to claim 4, characterized in that: The base film is made of at least one of a polyolefin film and a polyimide film.

8. The battery separator coating process according to claim 7, characterized in that: The base film has a thickness of 16-30 μm and a porosity of 40-60%.

9. The battery separator coating process according to claim 4, characterized in that: The thickener is at least one of hydroxyethyl cellulose, methyl hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, and sodium alginate, and the dispersant is at least one of sodium polyacrylate and ammonium polyacrylate.

10. A battery separator, characterized in that: It is prepared based on a battery separator coating process according to any one of claims 1 to 9.

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