A battery separator with a porous ceramic modified coating and a preparation method thereof

Abstract

The present invention discloses a battery separator with a modified porous ceramic coating and a preparation method thereof, which includes a base film and at least one first coating disposed on one surface of the base film. The first coating includes modified porous ceramic particles, which contain porous ceramic particles and a polymer electrolyte filled in a plurality of pores of the porous ceramic particles. Due to the high porosity and specific surface area of the porous ceramic particles, the polymer electrolyte enters its pores to additionally provide an ion transport channel, enhancing the ion conduction ability of the separator. And based on the antifreeze characteristics of the polymer electrolyte, the capacity retention rate of the battery during operation in a low-temperature environment can be improved at the same time.

Description

Technical Field

[0001] The present invention relates to the field of battery separators, specifically to the modification of separator coatings, and particularly to the use of ceramic particles for modification to enhance the performance of the separator and the battery. Background Art

[0002] With the rapid development of portable electronic devices and electric vehicles, the demand for high-performance batteries is increasing day by day; as a key component in the battery, the performance of the battery separator also directly affects the overall performance of the battery; currently, commercial batteries have higher requirements for the cycle capacity retention rate and rate performance of the battery. Therefore, improving the ionic conductivity of the separator and thus enhancing the cycle capacity retention rate and rate performance of the battery has become a development direction in the separator market.

[0003] Traditionally, to solve the conductivity and mechanical properties of battery separators, ceramic particles are coated on the surface of the battery separator to provide sufficient thermal stability for the separator and ensure the conductivity path of the separator; on the other hand, to increase the ionic conductivity, the porosity of the ceramic particles can provide sufficient electrolyte wettability, enabling the ceramic particles to serve as good ion transport media; however, in a low-temperature working environment, due to freezing and solidification, the liquid electrolyte slows down the ion transfer efficiency and also leads to a decrease in the capacity retention rate and rate performance of the battery. Summary of the Invention

[0004] Based on the limitations of the above technical means, the main purpose of the present invention is to improve the anti-freezing performance of the battery separator and enhance its capacity retention rate and rate performance to meet the requirements of the current battery separator market; accordingly, one aspect of the present invention is to provide a battery separator with a porous ceramic modified coating, comprising: a base film and at least one first coating disposed on one surface of the base film, which includes modified porous ceramic particles, which comprise: porous ceramic particles having a plurality of pores; and a polymer electrolyte filled in the plurality of pores.

[0005] For the battery separator as described above, the porous ceramic particles include at least one of porous alumina, porous barium titanate, porous silica, porous titanium dioxide, porous silicon nitride, and porous silicon carbide.

[0006] For the battery separator as described above, the polymer electrolyte includes at least one of poly(ethylene oxide) (PEO) polymer electrolyte, polyacrylonitrile (PAN) polymer electrolyte, polymethyl methacrylate (PMMA) polymer electrolyte, and polyvinylidene fluoride (PVDF) polymer electrolyte.

[0007] For the battery separator as described above, the material of the base film is at least one of polyethylene and polypropylene.

[0008] The battery separator as described above includes two or more of the first coatings, wherein the modified porous ceramic particles included in any one of the first coatings are the same as or different from the modified porous ceramic particles included in another adjacent first coating.

[0009] The battery separator as described above further includes a second coating, which is disposed on the other surface of the base film relative to the first coating, and the second coating is the same as or different from the first coating.

[0010] Another aspect of the present invention is to provide a method for preparing a battery separator with a porous ceramic modified coating, including:

[0011] Step S1: Prepare modified porous ceramic particles, which include:

[0012] Porous ceramic particles, which have a plurality of pores; and

[0013] A polymer electrolyte, which is filled in the plurality of pores;

[0014] Step S2: Mix the modified porous ceramic particles and a binder in a dispersion solution to obtain a coating slurry; and

[0015] Step S3: Coat the coating slurry on a base film to obtain a wet separator, and dry the wet separator to obtain the battery separator with the porous ceramic modified coating.

[0016] In the preparation method as described above, step S1 further includes the following sub-steps:

[0017] Step S10: Uniformly mix the porous ceramic particles and the polymer electrolyte in a solvent;

[0018] Step S11: Exclude the air in the plurality of pores so that the polymer electrolyte fills into the plurality of pores to obtain the modified porous ceramic particles.

[0019] In the preparation method as described above, step S1 further includes step S12: Dry the modified porous ceramic particles so that the polymer electrolyte solidifies in the plurality of pores.

[0020] In the preparation method as described above, in step S2, the dispersion solution includes a dispersant, and the dispersant is selected from at least one of polyvinylpyrrolidone, polyethylene, polypropylene, sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate, and polyethylene glycol.

[0021] The preparation method as described above is characterized in that the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyacrylamide, melamine, gelatin, sodium alginate, polyvinyl alcohol, polyvinyl butyral, hydroxyethyl cellulose, and polyurethane.

[0022] The preparation method as described above is characterized in that the dispersion solution further includes a thickening agent and a wetting agent.

[0023] The thickening agent includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbomer resin, and polyethylene oxide; the wetting agent includes at least one of polyether-modified silicone, fatty alcohol ethers, and polyvinyl alcohol.

[0024] The battery separator with a porous ceramic modified coating and its preparation method provided by the present invention use porous ceramic particles filled with polymer electrolyte in the coating, thereby improving the ionic conductivity of the separator, further improving the cycle capacity retention rate and rate performance of the battery, and overcoming the problem of performance degradation of the liquid electrolyte in a low-temperature working environment. Description of the Drawings

[0025] Figure 1A It is a cross-sectional schematic diagram for explaining the layered structure of the battery separator in the first embodiment.

[0026] Figure 1B It is a cross-sectional schematic diagram for explaining the internal structure of the modified porous ceramic particles in the first embodiment.

[0027] Figure 2 It is a cross-sectional schematic diagram for explaining the layered structure of the battery separator in the second embodiment.

[0028] Figure 3 It is a cross-sectional schematic diagram for explaining the layered structure of the battery separator in the third embodiment; and

[0029] Figures 4A to 4C It is a block flow chart for explaining the specific process of the preparation method of the battery separator with a porous ceramic modified coating in the fourth embodiment. Detailed Embodiments

[0030] The following illustrates the specific embodiments of the present invention with several examples and accompanying drawings. Please refer to Figures 1A to 1B In the first embodiment of the present invention, a battery separator 100 with a porous ceramic modified coating is provided, which is characterized in that it includes: a base film 1 and at least one first coating 2 provided on one surface of the base film 1, which includes modified porous ceramic particles 20, which include: porous ceramic particles 21, which have a plurality of pores 22; and a polymer electrolyte 23, filled in the plurality of pores 22.

[0031] In some other embodiments, in order to allow a sufficient amount of the polymer electrolyte 23 to enter the internal channels intertwined by the plurality of pores 22 through the surface of the porous ceramic particles 21, the average pore diameter of the plurality of pores 22 is at least 5 to 100 nm, preferably 10 to 80 nm, more preferably 20 to 60 nm; on the other hand, the level of ionic conductivity also depends on the contact area between the porous ceramic particles 21 and the polymer electrolyte 23. In other words, the larger the specific surface area of the porous ceramic particles 21, the larger the contact area between them and the polymer electrolyte 23; in some examples, the specific surface area of the porous ceramic particles 21 is 10 to 100 m 2 / g, preferably 20 to 60 m 2 / g.

[0032] In multiple embodiments, the thickness of the first coating 2 is 0.5 to 4 μm.

[0033] In multiple embodiments, the particle size of the porous ceramic particles 21 is 0.05 μm to 2 μm, and the preferred particle size is 0.1 to 1 μm.

[0034] In multiple embodiments, the porous ceramic particles 21 include at least one of porous alumina, porous barium titanate, porous silica, porous titanium dioxide, porous silicon nitride, and porous silicon carbide,

[0035] preferably porous alumina.

[0036] In multiple embodiments, the polymer electrolyte 23 includes at least one of a polyethylene oxide (PEO) polymer electrolyte, a polyacrylonitrile (PAN) polymer electrolyte, a polymethacrylate (PMMA) polymer electrolyte, a polyvinylidene fluoride (PVDF) polymer electrolyte, a poly(propylene carbonate) polymer electrolyte, a polycarbonate polymer electrolyte, a polysiloxane polymer electrolyte, and a phosphazene polymer electrolyte. Preferably, it is the polyethylene oxide (PEO) polymer electrolyte. The polyethylene oxide (PEO) polymer electrolyte can be formed by compounding succinonitrile (SN) with polyethylene oxide (PEO), denoted as PEO-SN. Among them, the ratio of succinonitrile (SN) to polyethylene oxide (PEO) is 1:4.2.

[0037] In multiple embodiments, the material of the base film 1 is at least one of polyethylene and polypropylene,

[0038] Preferably, the base film 1 is a polyethylene microporous membrane, a polypropylene microporous membrane, or a polypropylene / polyethylene composite microporous membrane. Preferably, the thickness of the base film 1 is 3 to 20 μm, and the air permeability value of the base film 1 is 70 to 300 s / 100 c.c.

[0039] The second embodiment of the present invention is to provide a battery separator 100 with a porous ceramic modified coating. Its specific structure and materials are substantially the same as those of the first embodiment, except that it includes two or more of the first coatings 2, as Figure 2 shown. Among them, the modified porous ceramic particles 20 included in any one of the first coatings 2 are the same as or different from the modified porous ceramic particles 20 included in another adjacent first coating 2.

[0040] The third embodiment of the present invention is to provide a battery separator 100 with a porous ceramic modified coating. Its specific structure and materials are substantially the same as those of the first embodiment, except that it further includes a second coating 3, as Figure 3 shown. Relative to the first coating 2 disposed on the other surface of the base film 1, the second coating 3 is the same as or different from the first coating 2.

[0041] The fourth embodiment of the present invention is to provide a method for preparing a battery separator 100 with a porous ceramic modified coating, as Figure 4A shown. It includes:

[0042] Step S1: Prepare modified porous ceramic particles 20, which includes:

[0043] Porous ceramic particles 21, which have a plurality of pores 22; and

[0044] Polymer electrolyte 23, filled in the plurality of pores 22

[0045] Step S2: Mix the modified porous ceramic particles 20 and a binder in a dispersion solution to obtain a coating slurry; and

[0046] Step S3: Coat the coating slurry on the base film to obtain a wet separator, and dry the wet separator to obtain a battery separator with a porous ceramic modified coating.

[0047] In multiple embodiments, as Figure 4B shown, the step S1 further includes the following sub-steps:

[0048] Step S10: Uniformly mix the porous ceramic particles 21 and the polymer electrolyte 23 in a solvent;

[0049] Step S11: Exclude the air in the plurality of pores 22 so that the polymer electrolyte 23 fills into the plurality of pores 22 to obtain the modified porous ceramic particles 20.

[0050] In some examples, a slurry mixed with porous ceramic particles 21 and a polymer electrolyte 23 can be introduced into a vacuum device for evacuation to remove the air in the plurality of pores 22. When the air is exhausted, the negative pressure effect formed will cause the polymer electrolyte 23 to fill into the plurality of pores 22 at a specific rate. It can be understood that if the degree of vacuum changes too much per unit time and the rate at which the polymer electrolyte 23 enters the plurality of pores 22 is too fast, the air cannot be completely exhausted, resulting in the formation of air holes in the polymer electrolyte 23, and the air holes are wrapped by the polymer electrolyte 23, and the electrolyte cannot penetrate either, causing the interfacial resistance to be too large and affecting the ion transport rate. Therefore, in a specific example, at an air extraction rate of 100 to 600 liters per minute, the pressure is reduced from 1 atmosphere to 10 -1 to 10 -2 Pa within 1 to 20 minutes to complete the filling of the porous ceramic particles 21. Preferably, at an air extraction rate of 150 to 400 liters per minute, the pressure is reduced from 1 atmosphere to 10 -1 to 10 -2 Pa.

[0051] In the above embodiments, the solvent includes at least one of water, methanol, ethanol, propanol, n-butanol, isopropanol, decalin, acetic acid, glycerol, N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF), and preferably N,N-dimethylformamide (DMF).

[0052] In multiple embodiments, the step S1 further includes a step S12: drying the modified porous ceramic particles 20 to remove the solvent so that the polymer electrolyte 23 solidifies in the plurality of pores 22.

[0053] In multiple embodiments, in step S2, the dispersion solution includes a dispersant selected from at least one of polyvinylpyrrolidone, polyethylene, polypropylene, sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate, and polyethylene glycol, and preferably sodium polyacrylate. Among them, the mass ratio of the dispersant to the coating slurry is 1:(50 to 2000).

[0054] In multiple embodiments, the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyacrylamide, melamine, gelatin, sodium alginate, polyvinyl alcohol, polyvinyl butyral, hydroxyethyl cellulose, polyurethane, acrylate, polyacrylate, and polymethacrylate, and preferably at least one of acrylate, polyacrylate, and polymethacrylate.

[0055] In multiple embodiments, in step S2, taking the weight of the coating slurry as 100 wt%, it contains 20 to 50 wt% of the modified porous ceramic particles 20.

[0056] In multiple embodiments, as Figure 4C shown, step S2 further includes the following sub-steps:

[0057] Step S20: Add and uniformly disperse the modified porous ceramic particles 20 in a dispersion solution to

[0058] obtain a first pre-coated slurry;

[0059] Step S21: Add and uniformly disperse a thickener in the first pre-coated slurry to obtain a second

[0060] pre-coated slurry;

[0061] Step S22: Add and uniformly disperse the binder in the second pre-coated slurry to obtain a third

[0062] pre-coated slurry; and

[0063] Step S23: Add and uniformly disperse a wetting agent in the third pre-coated slurry to obtain the coating slurry.

[0064] In the above embodiments, the thickener includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbopol resin, polyethylene oxide, and preferably sodium carboxymethyl cellulose; in some embodiments, the mass ratio of the thickener to the modified porous ceramic particles 20 is (0.1 to 2):100.

[0065] In the above embodiments, the wetting agent includes at least one of polyether-modified silicone, polyvinyl alcohol, fatty alcohol ethers, and preferably polyether-modified silicone; in some embodiments, the mass ratio of the wetting agent to the modified porous ceramic particles 20 is (0.01 to 2):100; in some embodiments, the manufacturer of the polyether-modified silicone is Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0066] In multiple embodiments, in step S3, the coating method of the coating slurry can be one of gravure printing, knife coating, extrusion coating or wire bar coating, wherein the coating position of the coating slurry is any one surface or both surfaces of the base film 1.

[0067] In multiple embodiments, in step S3, the drying temperature is 40 to 150 °C, and the drying time is 0.01 hour to 0.5 hour; preferably, the drying is drying by baking.

[0068] Example 1

[0069] Step 10: Dissolve 100 g of PEO-SN polymer electrolyte in 100 g of N,N-dimethylformamide (DMF), and then add 100 g of porous alumina powder and stir to obtain a slurry. The pore size of the porous alumina powder is 10 nm, and the specific surface area is 15.2 m 2 / g; The preparation method of PEO-SN includes the following steps: Dissolve PEO, LiC IO 4 , and LLZTO filler in anhydrous acetonitrile, stir at room temperature for 6 h to form a homogeneous solution, where the molar ratio of PEO monomer to L iCIO 4 is 18:1, and LLZTO accounts for 15 wt.% of the solid mass of the mixture; Then, add a certain amount of SN to the mixed solution, and the ratio of SN to PEO is 1:4.2, stir for 12 h; Cast the prepared solution on a polytetrafluoroethylene substrate and dry it in a vacuum oven at 55 °C for 72 h; Finally, store the electrolyte in

[0070] a glove box filled with argon for subsequent operations;

[0071] Step 11: Place the slurry in a vacuum device and perform vacuum treatment to discharge the air in the pores of the porous alumina powder, so that the PEO-SN polymer electrolyte fills into the pores of the porous alumina powder to

[0072] obtain modified porous alumina powder;

[0073] Step 12: Filter out the porous ceramic precursor, perform drying treatment to remove the dissolution, separate the powder particles of the modified porous alumina powder, and solidify the PEO-SN polymer electrolyte in the pores of the porous alumina powder to obtain modified porous ceramic particles 20, which are in powder form.

[0074] Step 20: Add 100 g of modified porous ceramic particles 20 to the dispersion solution, stir with a magnetic stirrer at 500 rpm for 1 h, and then grind to obtain a first pre-coated slurry, where

[0075] the dispersion solution is prepared by dissolving 0.5 g of sodium polyacrylate in 150 g of deionized water and then stirring with a magnetic

[0076] stirrer at a rate of 500 rpm for 6 h;

[0077] Step 21: Add 10 g of sodium carboxymethylcellulose aqueous solution to the first pre-coated slurry and stir for 30 minutes to obtain a second pre-coated slurry;

[0078] Step 22: Add 20 g of acrylate emulsion to the second pre-coated slurry, and stir with a magnetic stirrer at 300 rpm for 1 hour to obtain the third pre-coated slurry;

[0079] Step 22: Add 0.05 g of polyether-modified silicone to the obtained third pre-coated slurry,

[0080] Stir with a magnetic stirrer at 300 rpm for 12 hours to obtain a uniform coating slurry;

[0081] Step 3: Use a film coater to coat the coating slurry on one side surface of a polyethylene film with a thickness of 9 μm, and then dry it in an oven at 60 °C for 30 minutes to obtain a separator with a first coating on one side, wherein the thickness of the first coating is 2 μm.

[0082] Example 2

[0083] Same as Example 1, except that the pore diameter of the porous alumina powder is 20 nm and the specific surface area is 25.1 m 2 / g.

[0084] Example 3

[0085] Same as Example 1, except that the pore diameter of the porous alumina powder is 40 nm and the specific surface area is 40.5 m 2 / g.

[0086] Example 4

[0087] Same as Example 1, except that the pore diameter of the porous alumina powder is 60 nm and the specific surface area is 57.8 m 2 / g.

[0088] Comparative Example 1

[0089] Same as Example 1, except that the preparation starts directly from Step 20, and only 100 g of conventional non-porous alumina powder is added.

[0090] Comparative Example 2

[0091] Same as Example 1, except that the preparation starts directly from Step 20, and only 100 g of porous alumina powder is added, which is not filled with a gel polymer electrolyte, and the pore diameter is 40 nm and the specific surface area is 40.5 m 2 / g.

[0092] Comparative Example 3

[0093] Same as Example 1, with the difference that it starts preparation directly from Step 20, where only 100 grams of porous alumina powder is added, which is not filled with gel polymer electrolyte, and the pore diameter is 60 nm, and the specific surface area is 58.7 m 2 / g.

[0094] Ionic conductivity test

[0095] Test method: Cut 5 diaphragms with a size of 50 mm * 50 mm, put the diaphragms into the electrolyte, keep them sealed and soaked for at least 30 minutes, and test the AC impedance of the soaked diaphragms; take the number of diaphragm layers as the abscissa and the diaphragm resistance as the ordinate, calculate the slope of the curve, which is the diaphragm impedance value, and deduce and calculate the ionic conductivity and MacMullin value of the diaphragm according to the diaphragm impedance value (R = k × 1).

[0096] Battery cycle capacity test

[0097] Test method: Make a soft-pack battery cell with a diaphragm having a width of 86 mm, at a temperature of 25°C ± 2°C,

[0098] perform 1C cyclic charge and discharge for 1000 times, and record the cyclic capacity retention rate of the battery.

[0099] Battery low-temperature capacity test

[0100] Test method: Make a soft-pack battery cell with a diaphragm having a width of 86 mm, perform 1 charge and discharge cycle at room temperature,

[0101] keep it in an environment of -10°C for 3 hours, perform 1C charge and discharge cycle 10 times, and record the charge and discharge capacity retention rate each time,

[0102] calculate its average value.

[0103] Battery capacity retention rate test

[0104] Test method: Make a soft-pack battery cell with a diaphragm having a width of 86 mm, in an environment of 20°C ± 5°C, first charge it to full capacity at a constant current and constant voltage of 1C, and then discharge it at a rate of 5C, and record the discharge capacity retention rate.

[0105] The following summarizes the performance tests of the battery diaphragms prepared in Examples 1 to 4 and Comparative Examples 1 to 4

[0106] Results are shown in Table 1 below:

[0107] Table 1

[0108]

[0109] As can be seen from Table 1, compared with Examples 1 to 4, as the pore diameter and specific surface area of the porous alumina increase,

[0110] As the filling amount of the PEO-SN polymer electrolyte in the pore diameter increases, the ionic conductivity of the separator increases accordingly, and the battery cycle capacity retention rates of Examples 1 to 3 also increase correspondingly. However, there is no obvious difference in the ionic conductivity of the separator and the battery cycle capacity retention rate in Example 4 compared with Example 3, and there is a decrease compared with Example 3; comparing the low-temperature retention rates of the batteries in Examples 1 to 4, due to the increase in the content of the PEO-SN polymer electrolyte, the low-temperature performance is also improved accordingly.

[0111] Comparing the results of Examples 1 to 4 and Comparative Example 1, the porous alumina powder filled with the PEO-SN polymer electrolyte significantly improves the ionic conductivity of the battery separator, and increases the battery cycle capacity retention rate and the battery low-temperature capacity retention rate.

[0112] Comparing Examples 2 to 3 and Comparative Examples 2 to 3, compared with the porous alumina with the same pore diameter, the porous alumina powder modified by filling with the PEO-SN polymer electrolyte can significantly increase the ionic conductivity of the separator, the battery cycle capacity retention rate and the low-temperature capacity retention rate when coated on the separator; this is because the pore diameter of the porous alumina is too small and the capillary effect is obvious, resulting in difficulty for the electrolyte to penetrate into the pores. However, filling the pores of the porous alumina with the PEO-SN polymer electrolyte by vacuum treatment ensures that the PEO-SN polymer electrolyte penetrates into its pores.

[0113] The battery separator 100 with the porous ceramic modified coating and its preparation method provided by the present invention specifically exhibit the following advantages: Since the pores 22 of the modified porous ceramic particles 20 in the separator coating are filled with the polymer electrolyte 23, the electrolyte can effectively infiltrate the modified porous ceramic particles 20, promoting the ion exchange rate in its pores 22, thereby increasing the ionic conductivity of the overall separator; in addition, the battery separator 100 with the porous ceramic modified coating also increases the battery cycle capacity retention rate and the rate performance.

[0114] On the other hand, the battery separator 100 with the porous ceramic modified coating also improves the problem of performance degradation of the battery at low temperatures. By utilizing the antifreeze characteristics of the polymer electrolyte 23, the battery separator can still maintain the ion channels at low temperatures, maintain the ionic conductivity of the battery separator, and increase the battery low-temperature capacity retention rate.

[0115] The above content related to common general knowledge will not be described in detail, and those skilled in the art can understand it.

[0116] The above-described embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A battery separator with a porous ceramic modified coating, characterized in that: include: Basement membrane; and At least one first coating layer is disposed on one surface of the base film, and includes modified porous ceramic particles, wherein the modified porous ceramic particles include: Porous ceramic particles having a plurality of pores; and The polymer electrolyte is filled in the plurality of pores.

2. The battery separator according to claim 1, characterized in that: The average pore size of the plurality of pores is 5 to 100 nanometers, and the specific surface area of ​​the porous ceramic particles is 10 to 100 m 2 / g.

3. The battery separator according to claim 1, characterized in that: The porous ceramic particles have a particle size of 0.05 μm to 2 μm.

4. The battery separator according to claim 1, characterized in that: The method comprises two or more first coating layers, wherein the modified porous ceramic particles contained in any one of the first coating layers are the same as or different from the modified porous ceramic particles contained in another adjacent first coating layer.

5. The battery separator according to claim 1, characterized in that: The invention further comprises a second coating layer, which is disposed on another surface of the base film relative to the first coating layer, and the second coating layer is the same as or different from the first coating layer.

6. The battery separator according to any one of claims 1 to 5, characterized in that: The porous ceramic particles include at least one of porous alumina, porous barium titanate, porous silica, porous titanium dioxide, porous silicon nitride, and porous silicon carbide; the polymer electrolyte includes at least one of polyethylene oxide (PEO) polymer electrolyte, polyacrylonitrile (PAN) polymer electrolyte, polymethacrylate (PMMA) polymer electrolyte, and polyvinylidene fluoride (PVDF) polymer electrolyte.

7. The battery separator according to claim 6, characterized in that: The base film is made of at least one of polyethylene and polypropylene.

8. A method for preparing a battery separator with a porous ceramic modified coating, characterized in that: include: Step S1: preparing modified porous ceramic particles, which comprises: Porous ceramic particles having a plurality of pores; and A polymer electrolyte filled in the plurality of pores; Step S2: mixing the modified porous ceramic particles and a binder in a dispersion solution to obtain a coating slurry; as well as Step S3: coating the coating slurry on a base film to obtain a wet separator, and drying the wet separator to obtain a battery separator having the porous ceramic modified coating.

9. The preparation method according to claim 8, characterized in that: The step S1 further comprises the following sub-steps: Step S10: uniformly mixing the porous ceramic particles and the polymer electrolyte in a solvent; Step S11: Expelling air from the plurality of pores so that the polymer electrolyte fills the plurality of pores to obtain the modified porous ceramic particles.

10. The preparation method according to claim 9, characterized in that: The step S1 further comprises: Step S12: Drying the modified porous ceramic particles to solidify the polymer electrolyte in the plurality of pores.

11. The preparation method according to claim 8, characterized in that: In step S2, the dispersion solution includes a dispersant, and the dispersant is selected from at least one of polyvinyl pyrrolidone, polyethylene, polypropylene, sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate and polyethylene glycol; the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyacrylic acid, polyacrylonitrile, polymethyl methacrylate, polyacrylamide, melamine, gelatin, sodium alginate, polyvinyl alcohol, polyvinyl butyral, hydroxyethyl cellulose and polyurethane.

12. The preparation method according to claim 11, characterized in that: The dispersion solution further includes a thickener and a wetting agent. The thickener includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbopol resin, and polyoxyethylene; the wetting agent includes at least one of polyether-modified siloxane, fatty alcohol ether, and polyvinyl alcohol.

13. The preparation method according to claim 12, characterized in that: The mass ratio of the thickener to the modified porous ceramic particles is (0.1 to 2):100; the mass ratio of the wetting agent to the modified porous ceramic particles is (0.01 to 2):

100.

14. The preparation method according to claim 12, characterized in that: The mass ratio of the dispersant to the coating slurry is 1:(50 to 2000).

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