Battery separator comprising porous ceramic modified coating, and preparation method therefor

Abstract

Disclosed in the present invention are a battery separator comprising a porous ceramic modified coating, and a preparation method therefor. The battery separator comprises a base membrane and at least one first coating arranged on one surface of the base membrane, the first coating comprising modified porous ceramic particles, wherein the modified porous ceramic particles 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 the pores of the porous ceramic particles, thereby providing additional ion transport channels and enhancing the ion conduction capability of the separator; and on the basis of the anti-freezing properties of the polymer electrolyte, the capacity retention rate of a battery operating in a low-temperature environment can be improved.

Description

Battery separator with porous ceramic modified coating and method of making the same TECHNICAL FIELD

[0001] The present invention relates to the field of battery separators, and in particular to the modification of the coating of the separator, and more particularly to the use of ceramic particles to improve the performance of the separator and the battery. BACKGROUND

[0002] With the rapid development of portable electronic devices and electric vehicles, there is an increasing demand for high-performance batteries. As a key component in batteries, the performance of the battery separator 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 the cycle capacity retention rate and rate performance of the battery has become a direction for the development of the separator market.

[0003] Traditionally, to address the electrical conductivity and mechanical properties of the battery separator, ceramic particles are applied to the surface of the battery separator to provide sufficient thermal stability for the separator and ensure the electrical conduction path of the separator. On the other hand, to increase the ionic conductivity, the porosity of the ceramic particles can provide sufficient electrolyte wettability, so that the ceramic particles can serve as a good ion transport medium. However, in low-temperature working environments, the freezing and solidification of the liquid electrolyte slow down the ion transfer efficiency and also lead to a decrease in the capacity retention rate and rate performance of the battery. SUMMARY

[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 needs 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 a surface of the base film, which comprises modified porous ceramic particles, comprising: porous ceramic particles having a plurality of pores; and a polymer electrolyte filled in the plurality of pores.

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

[0006] The polymer electrolyte of the battery separator as described above comprises at least one of polyethylene oxide (PEO) polymer electrolyte, polyacrylonitrile (PAN) polymer electrolyte, polymethyl acrylate (PMMA) polymer electrolyte, and polyvinylidene fluoride (PVDF) polymer electrolyte.

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

[0008] The battery separator as previously described, further comprising two or more of the first coating, wherein the modified porous ceramic particles comprised in any of the first coating are the same as or different from the modified porous ceramic particles comprised in another of the first coating.

[0009] The battery separator as previously described, further comprising a second coating disposed on another surface of the base film relative to the first coating, the second coating being the same as or different from the first coating.

[0010] Another aspect of the present disclosure is to provide a method for preparing a battery separator with a porous ceramic modified coating, comprising: step S1: preparing modified porous ceramic particles, comprising: 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; and step S3: coating the coating slurry on a base film to obtain a wet separator, and drying the wet separator to obtain the battery separator with the porous ceramic modified coating.

[0011] The method for preparing as previously described, 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: excluding air in the plurality of pores so that the polymer electrolyte is filled in the plurality of pores to obtain the modified porous ceramic particles.

[0012] The method for preparing as previously described, the step S1 further comprises step S12: drying the modified porous ceramic particles so that the polymer electrolyte is solidified in the plurality of pores.

[0013] The method for preparing as previously described, in step S2, the dispersion solution comprises a dispersant selected from at least one of polyvinylpyrrolidone, polyethylene, polypropylene, sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate, and polyethylene glycol.

[0014] The method for preparing as previously described, wherein the binder comprises 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.

[0015] The preparation method as claimed in the preceding description, characterized in that the dispersion solution further comprises a thickening agent and a wetting agent, wherein the thickening agent comprises at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbopol resin, and polyoxyethylene; and the wetting agent comprises at least one of polyether-modified siloxane, fatty alcohol ether, and polyvinyl alcohol.

[0016] The porous ceramic modified coating battery separator and the preparation method thereof provided by the present application use porous ceramic particles filled with polymer electrolyte in the coating, thereby improving the ion conductivity of the separator, further improving the cycle capacity retention rate and the rate performance of the battery, and overcoming the performance degradation of the liquid electrolyte in low-temperature working environments. BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1A is a schematic cross-sectional view illustrating the layered structure of the battery separator in the first embodiment;

[0018] FIG. 1B is a schematic cross-sectional view illustrating the internal structure of the modified porous ceramic particles in the first embodiment;

[0019] FIG. 2 is a schematic cross-sectional view illustrating the layered structure of the battery separator in the second embodiment;

[0020] FIG. 3 is a schematic cross-sectional view illustrating the layered structure of the battery separator in the third embodiment; and

[0021] FIGS. 4A to 4C are block flowcharts illustrating the specific processes of the preparation method of the porous ceramic modified coating battery separator in the fourth embodiment. DETAILED DESCRIPTION

[0022] The following describes the specific embodiments of the present application by means of several examples with reference to FIGS. 1A to 1B. The first embodiment of the present application provides a porous ceramic modified coating battery separator 100, characterized in that it comprises a base film 1 and at least one first coating layer 2 arranged on one surface of the base film 1, which comprises modified porous ceramic particles 20, including porous ceramic particles 21 having a plurality of pores 22, and polymer electrolyte 23 filled in the plurality of pores 22.

[0023] In other embodiments, in order to allow sufficient polymer electrolyte 23 to pass through the surface of the porous ceramic particles 21 into the internal channels interwoven by the plurality of pores 22, the average pore size of the plurality of pores 22 is at least 5 to 100 nm, preferably 10 to 80 nm, and more preferably 20 to 60 nm; on the other hand, the 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 the porous ceramic particles 21 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.

[0024] In some embodiments, the first coating layer 2 has a thickness of 0.5 to 4 μm.

[0025] In some embodiments, the porous ceramic particles 21 have a particle size of 0.05 μm to 2 μm, and preferably a particle size of 0.1 to 1 μm.

[0026] In some embodiments, the porous ceramic particles 21 comprise at least one of porous alumina, porous barium titanate, porous silica, porous titanium dioxide, porous silicon nitride, porous silicon carbide, and preferably porous alumina.

[0027] In some embodiments, the polymer electrolyte 23 comprises 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 polypropylene carbonate polymer electrolyte, a polycarbonate polymer electrolyte, a polysiloxane polymer electrolyte, and a phosphazene polymer electrolyte, and preferably the polyethylene oxide (PEO) polymer electrolyte, which can be composed of succinonitrile (SN) and polyethylene oxide (PEO) at a ratio of 1:4.2, denoted as PEO-SN.

[0028] In some embodiments, the base film 1 is made of at least one of polyethylene and polypropylene, and preferably the base film 1 is a polyethylene microporous film, a polypropylene microporous film, or a polypropylene / polyethylene composite microporous film, and preferably the base film 1 has a thickness of 3 to 20 μm and a gas permeability of 70 to 300 s / 100 c.c.

[0029] A second embodiment of the present application is to provide a porous ceramic modified coating battery separator 100, which has substantially the same structure and material as the first embodiment, but includes two or more first coatings 2, as shown in FIG. 2, wherein the modified porous ceramic particles 20 contained in any first coating 2 are the same as or different from the modified porous ceramic particles 20 contained in another first coating 2 adjacent thereto.

[0030] A third embodiment of the present application is to provide a porous ceramic modified coating battery separator 100, which has substantially the same structure and material as the first embodiment, but further includes a second coating 3, as shown in FIG. 3, which is disposed on another surface of the base film 1 opposite to the first coating 2, and is the same as or different from the first coating 2.

[0031] A fourth embodiment of the present application is to provide a method for preparing a porous ceramic modified coating battery separator 100, as shown in FIG. 4A, which includes: Step S1: preparing modified porous ceramic particles 20, which include: porous ceramic particles 21 having a plurality of pores 22; and a polymer electrolyte 23 filled in the plurality of pores 22; Step S2: mixing the modified porous ceramic particles 20 and a binder in a dispersion solution to obtain a coating slurry; and Step S3: coating the coating slurry on a base film to obtain a wet separator, and drying the wet separator to obtain a porous ceramic modified coating battery separator.

[0032] In some embodiments, as shown in FIG. 4B, the step S1 further includes the following sub-steps: Step S10: uniformly mixing the porous ceramic particles 21 and the polymer electrolyte 23 in a solvent; Step S11: removing 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.

[0033] In some examples, the slurry mixed with the porous ceramic particles 21 and the polymer electrolyte 23 can be introduced into a vacuumizing device for vacuumizing to remove air in the plurality of pores 22. When the air is removed, the negative pressure effect formed will cause the polymer electrolyte 23 to fill into the plurality of pores 22 at a certain rate. It can be understood that if the vacuum degree changes too much per unit time, the rate of the polymer electrolyte 23 entering the plurality of pores 22 is too fast, which causes air to be unable to be completely removed, so that air holes are formed in the polymer electrolyte 23, and the air holes are wrapped by the polymer electrolyte 23, and the electrolyte solution cannot be immersed, resulting in too large interface resistance and affecting the ion transmission rate. Therefore, in specific examples, the air exhaust rate is 100 to 600 liters per minute, and the pressure is reduced from 1 atmosphere to 10 -1 to 10 -2 Pa, preferably at a suction rate of 150 to 400 liters per minute, to 10 -1 to 10 -2 Pa.

[0034] In the above embodiments, the solvent includes at least one of water, methanol, ethanol, propanol, n-butanol, isopropanol, decalin, acetic acid and glycerol, N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), preferably N,N-dimethylformamide (DMF).

[0035] In some embodiments, the step S1 further comprises a step S12 of drying the modified porous ceramic particles 20 to remove the solvent, so as to solidify the polymer electrolyte 23 in the plurality of pores 22.

[0036] In some embodiments, in the 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, preferably sodium polyacrylate, wherein the mass ratio of the dispersant to the coating slurry is 1:(50 to 2000).

[0037] In some 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, polymethacrylate, preferably at least one of acrylate, polyacrylate and polymethacrylate.

[0038] In some embodiments, in the step S2, the coating slurry contains 20 to 50 wt% of the modified porous ceramic particles 20, based on 100 wt% of the coating slurry.

[0039] In some embodiments, as shown in FIG. 4C, the step S2 further comprises the following sub-steps:

[0040] Step S20: adding and uniformly dispersing the modified porous ceramic particles 20 in a dispersion solution to obtain a first pre-coating slurry;

[0041] Step S21: adding and uniformly dispersing a thickening agent in the first pre-coating slurry to obtain a second pre-coating slurry;

[0042] Step S22: adding and uniformly dispersing the binder in the second pre-coating slurry to obtain a third pre-coating slurry; and

[0043] Step S23: adding and uniformly dispersing a wetting agent in the third pre-coating slurry to obtain the coating slurry.

[0044] In the above embodiments, the thickening agent includes at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbopol resin, and polyethylene oxide, and preferably sodium carboxymethyl cellulose; in some embodiments, the mass ratio of the thickening agent to the modified porous ceramic particles 20 is (0.1 to 2): 100.

[0045] In the above embodiments, the wetting agent includes at least one of polyether-modified siloxane, polyvinyl alcohol, and fatty alcohol ether, and preferably polyether-modified siloxane; 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 polyether-modified siloxane is produced by Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0046] In some embodiments, in step S3, the coating method of the coating slurry can be one of gravure printing, blade coating, extrusion coating, or wire bar coating, and the coating position of the coating slurry is on any one surface or both surfaces of the base film 1.

[0047] In some embodiments, in step S3, the drying temperature is 40 to 150°C, and the drying time is 0.01 to 0.5 hours; preferably, the drying is baking.

[0048] Embodiment 1

[0049] Step 10: 100 grams of PEO-SN polymer electrolyte was dissolved in 100 grams of N,N-dimethylformamide (DMF), and then 100 grams of porous alumina powder with a pore size of 10 nm and a specific surface area of 15.2 m 2The preparation method of PEO-SN includes the following steps: PEO, LiCIO4, and LLZTO filler are dissolved in anhydrous acetonitrile, stirred at room temperature for 6h to form a homogeneous solution, wherein the molar ratio of PEO monomer to LiCIO4 is 18:1, and the solid mass ratio of LLZTO in the mixture is 15wt.%; then, a certain amount of SN is added to the mixed solution, the ratio of SN to PEO is 1:4.2, and stirring is carried out for 12h; the prepared solution is cast on a polytetrafluoroethylene substrate and dried in a vacuum oven at 55°C for 72h; finally, the electrolyte is stored in an argon-filled glove box for subsequent operation;

[0050] Step 11: The slurry is placed in a vacuum extraction device for vacuum extraction 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 obtain a modified porous alumina powder;

[0051] Step 12: The porous ceramic precursor is filtered out and dried to remove the solution, 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 a modified porous ceramic particle 20 in a powder form.

[0052] Step 20: 100 grams of modified porous ceramic particles 20 are added to the dispersion solution, and a magnetic stirrer is used for stirring at 500 rpm for 1 hour, followed by grinding to obtain a first pre-coating slurry, wherein the dispersion solution is prepared by dissolving 0.5 grams of sodium polyacrylate in 150 grams of deionized water, and then stirring at a speed of 500 rpm for 6 hours using a magnetic stirrer;

[0053] Step 21: 10 grams of a sodium carboxymethyl cellulose aqueous solution are added to the first pre-coating slurry, and stirring is carried out for 30 minutes to obtain a second pre-coating slurry;

[0054] Step 22: 20 grams of an acrylate emulsion are added to the second pre-coating slurry, and a magnetic stirrer is used for stirring at 300 rpm for 1 hour to obtain a third pre-coating slurry;

[0055] Step 22: 0.05 grams of a polyether-modified siloxane are added to the third pre-coating slurry to obtain a uniform coating slurry, and a magnetic stirrer is used for stirring at 300 rpm for 12 hours;

[0056] Step 3: A film coating machine is used to coat the coating slurry to one side surface of a polyethylene film with a thickness of 9μm, and then drying is carried out in an oven at 60°C for 30 minutes to obtain a single-side coated separator with a first coating layer, wherein the thickness of the first coating layer is 2μm.

[0057] Example 2

[0058] The same as example 1, the difference is that the pore size of the porous alumina powder is 20 nm, and the specific surface area is 25.1 m 2 / g.

[0059] Example 3

[0060] The same as example 1, the difference is that the pore size of the porous alumina powder is 40 nm, and the specific surface area is 40.5 m 2 / g.

[0061] Example 4

[0062] The same as example 1, the difference is that the pore size of the porous alumina powder is 60 nm, and the specific surface area is 57.8 m 2 / g.

[0063] Comparative example 1

[0064] The same as example 1, the difference is that the preparation is directly started from step 20, and only 100 grams of conventional non-porous alumina powder is added.

[0065] Comparative example 2

[0066] The same as example 1, the difference is that the preparation is directly started from step 20, and only 100 grams of porous alumina powder is added, which is not filled with gel polymer electrolyte, and the pore size is 40 nm, and the specific surface area is 40.5 m 2 / g.

[0067] Comparative example 3

[0068] The same as example 1, the difference is that the preparation is directly started from step 20, and only 100 grams of porous alumina powder is added, which is not filled with gel polymer electrolyte, and the pore size is 60 nm, and the specific surface area is 58.7 m 2 / g.

[0069] Ion conductivity test

[0070] Test method: cut 5 pieces of 50mm*50mm size separator, put the separator into the electrolyte, keep sealed soaking for at least 30 minutes, test the AC impedance of the soaked separator; take the separator layer number as the abscissa, and the separator resistance as the ordinate, calculate the slope of the curve, that is, the separator impedance value, and according to the separator impedance value, deduce the ion conductivity and MacMullin value of the separator (R=k*1).

[0071] Battery cycle capacity test

[0072] Test method: take the separator with a width of 86mm to make a soft package battery, and cycle charge and discharge at 1C for 1000 times at a temperature of 25℃±2℃, and record the cycle capacity retention rate of the battery.

[0073] Battery low temperature capacity test

[0074] Test method: take the width of 86 mm of the membrane to make soft package battery, normal temperature charge and discharge 1 cycle, 3 hours at-10℃ environment, 1C charge and discharge cycle 10 times, and record each charge and discharge capacity retention rate, calculate its average value.

[0075] Battery capacity retention rate test

[0076] Test method: take the width of 86 mm of the membrane to make soft package battery, in the environment of 20℃±5℃, respectively, first with 1C constant current constant voltage full charge, then according to 5C discharge rate, and record the discharge capacity retention rate.

[0077] The following summarizes the performance test results of the battery separator prepared by example 1 to 4 and comparative example 1 to 4, as shown in table 1 below: Table 1

[0078] As can be seen from table 1, comparative examples 1 to 4, with the increase of pore size and specific surface area of porous alumina, the filling amount of PEO-SN polymer electrolyte in the pore increases, the ionic conductivity of the separator increases, the cycle capacity retention rate of the battery of examples 1 to 3 also increases accordingly, but the ionic conductivity and cycle capacity retention rate of the battery of example 4 have no obvious difference compared with example 3, and compared with example 3, there is a decline; The low temperature retention rate of the battery of comparative examples 1 to 4, due to the increase of the content of PEO-SN polymer electrolyte, the low temperature performance is also improved.

[0079] Comparative examples 1 to 4 and comparative example 1, the filling of PEO-SN polymer electrolyte in porous alumina powder, significantly improves the ionic conductivity of the battery separator, and improves the cycle capacity retention rate and low temperature capacity retention rate of the battery.

[0080] Comparative examples 2 to 3 and comparative examples 2 to 3, compared with the same pore size of porous alumina, the filling of PEO-SN polymer electrolyte in the modified porous alumina powder can significantly improve the ionic conductivity of the separator, the cycle capacity retention rate and low temperature capacity retention rate of the battery; This is because the pore size of the porous alumina is too small, the capillary effect is obvious, which makes it difficult for the electrolyte to penetrate into the pores, and the filling of PEO-SN polymer electrolyte in the pores of the porous alumina by vacuum treatment ensures the penetration of PEO-SN polymer electrolyte into the pores.

[0081] The porous ceramic modified coating battery separator 100 and the preparation method thereof provided by the present application specifically exhibits the following advantages: due to the fact that the modified porous ceramic particles 20 in the separator coating are filled with polymer electrolyte 23 in the pores 22, the electrolyte can effectively infiltrate the modified porous ceramic particles 20, promote the ion exchange rate in the pores 22, and thus improve the overall ion conductivity of the separator; in addition, the porous ceramic modified coating battery separator 100 also improves the cycle capacity retention rate and the rate performance of the battery.

[0082] On the other hand, the porous ceramic modified coating battery separator 100 also improves the performance degradation problem of the battery at low temperature, uses the anti-freezing property of the polymer electrolyte 23 to make the battery separator still maintain the ion channel at low temperature, keeps the ion conductivity of the battery separator, and improves the low-temperature capacity retention rate of the battery.

[0083] The above content related to common knowledge is not described in detail, and those skilled in the art can understand it.

[0084] The above-described embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A battery separator with a porous ceramic modified coating, characterized by, The battery separator comprises: a base film; and at least one first coating layer disposed on one surface of the base film, which comprises modified porous ceramic particles, wherein the modified porous ceramic particles comprise: porous ceramic particles having a plurality of pores; and polymer electrolyte filled in the plurality of pores.

2. The battery separator of claim 1, wherein The average pore diameter of the plurality of pores is 5 to 100 nm, and the specific surface area of the porous ceramic particles is 10 to 100 m 2 / g.

3. The battery separator of claim 1, wherein the polymeric material is a polyamide. The porous ceramic particles have a particle size of 0.05 μm to 2 μm.

4. The battery separator of claim 1, wherein the polymeric material is a polyamide. The battery separator comprises two or more first coating layers, wherein the modified porous ceramic particles contained in any 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 of claim 1, wherein the polymeric material is a polyamide. The battery separator further comprises a second coating layer disposed on another surface of the base film relative to the first coating layer, which is the same as or different from the first coating layer.

6. The battery separator of any one of claims 1 to 5, wherein the polymeric material is a polyamide. The porous ceramic particles comprise at least one of porous alumina, porous barium titanate, porous silica, porous titanium dioxide, porous silicon nitride, and porous silicon carbide; and the polymer electrolyte comprises 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 of claim 6, wherein the polymeric material is a polyamide. The base film is made of at least one of polyethylene and polypropylene.

8. A method of making a battery separator with a porous ceramic modified coating, characterized in that, The battery separator comprises: Step S1: preparing modified porous ceramic particles, which comprise: porous ceramic particles having a plurality of pores; and 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; and 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 of the porous ceramic modified coating layer. The step S1 further comprises the following sub-steps:

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

10. The preparation method according to claim 9, characterized in that, Step S12: drying the modified porous ceramic particles so that the polymer electrolyte is solidified in the plurality of pores. In step S2, the dispersion solution comprises a dispersant selected from at least one of polyvinylpyrrolidone, polyethylene, polypropylene, sodium polyacrylate, ammonium polyacrylate, sodium hexametaphosphate, and polyethylene glycol; and the binder comprises 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.

11. The preparation method according to claim 8, characterized in that, The dispersion solution further comprises a thickening agent and a wetting agent, wherein the thickening agent comprises at least one of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, methyl hydroxyethyl cellulose, carbopol resin, and polyoxyethylene; and the wetting agent comprises at least one of polyether-modified siloxane, fatty alcohol ether, and polyvinyl alcohol.

12. The method of claim 11, wherein the step of preparing is characterized by, ​ 13. The preparation method according to claim 12, characterized in that, The mass ratio of the thickening agent 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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