Battery separator and method for manufacturing the same

Abstract

The present invention proposes a battery separator comprising at least one base film, at least one inorganic layer disposed on the base film, and a plurality of polymeric microparticles disposed on the inorganic layer, the density of which is lower than that of the inorganic layer. The method involves blending the polymeric microparticles with barium titanate to form a multilayer structure, coating the resulting slurry on the base film, and then baking it in an oven. During the baking process, due to the density difference between the barium titanate and the polymeric microparticles, the denser barium titanate sinks and the polymeric microparticles float, resulting in a battery separator with excellent heat resistance and high adhesion.

Description

【Technical Field】 【0001】 The present invention relates to the field of lithium-ion battery separators, and particularly to battery separators and their manufacturing methods. 【Background Art】 【0002】 The excessive use of fossil raw materials has caused serious environmental pollution problems. To address the above problems, the use of new energy materials to replace fossil raw materials has become particularly important. Lithium-ion batteries are widely used in household electrical appliances, power products, and energy storage products due to their advantages such as high energy density, high safety and stability, and long cycle life. 【0003】 A battery separator is an important component within a lithium battery. Currently, battery separators with a microporous structure are usually manufactured by extrusion, extraction, and stretching of polyolefin materials. To improve the heat resistance of the separator, a heat-resistant inorganic material (such as ceramics, cellulose, aramid, etc.) is usually coated on the polyolefin base film. However, inorganic particles have poor dispersibility, are prone to falling off, and have serious powder shedding, and need to be used in combination with other components, resulting in a significant increase in manufacturing costs. Also, to meet the requirements of the current battery manufacturing process, it is necessary to ensure strong adhesiveness between the separator and the electrode plate to prevent the displacement of the electrode tabs. Current means for producing separators with high heat resistance and high adhesiveness usually involve coating an adhesive layer (PVDF) on inorganic particle powder. However, since PVDF has a relatively high softening point temperature, it is difficult to reach the softening point of PVDF when the hot press temperature is low, resulting in no obvious adhesive force between the separator and the positive and negative electrode plates. 【0004】 The battery separator proposed by this invention effectively solves the problems of existing battery separators, such as low heat resistance, a narrow hot-press process window between the separator and the electrode plate, the need for two coatings to manufacture separators with high heat resistance and high adhesion, the consumption of a large amount of energy, the complex composition of the coating material, and the poor stability of the slurry, which causes large fluctuations in the physical properties of the coating during the coating process. It offers superior performance compared to conventional separators. [Overview of the project] 【0005】 The object of the present invention is to have at least one substrate film, At least one inorganic layer located on the aforementioned substrate, The present invention proposes battery parameters characterized by including a plurality of polymer nanoparticles located on the inorganic layer and having a density lower than that of the inorganic layer. 【0006】 Preferably, the inorganic layer contains one or more of the following: barium titanate, alumina, silica, and titanium dioxide. 【0007】 Preferably, the polymer fine particles include one or more of the following: a polyacrylonitrile layer, a polystyrene layer, a polyvinylidene fluoride layer, a polymethyl methacrylate layer, and a polyacrylamide layer. 【0008】 Preferably, the polymer fine particles have a vegetable oil layer on the outside. Preferably, the vegetable oil layer contains one or more of the following: sunflower seed oil, Chinese tallow tree seed oil, olive oil, rubber seed oil, castor oil, tung oil, and palm oil. 【0009】 Preferably, the polymer fine particles further contain a plurality of cellulose nanofibrils, the plurality of cellulose nanofibrils located outside the vegetable oil layer, and a portion of the plurality of cellulose nanofibrils connected to the inorganic layer. Preferably, the cellulose nanofibril includes one or more of the following: absorbent cotton, paper pulp, wood pulp, and hemp. 【0010】 Another object of the present invention is the step of mixing vegetable oil, N-methylethanolamine, and a catalyst, sealing and heating to obtain a vegetable oil-based precursor; mixing the vegetable oil-based precursor and an anhydrous, sealing and heating to obtain a vegetable oil-based acrylate monomer; mixing the vegetable oil-based acrylate monomer, peroxybenzoic acid, and sodium carbonate, sealing and stirring at room temperature to obtain a vegetable oil-based acrylate epoxy monomer; and uniformly mixing the vegetable oil-based acrylate epoxy monomer, styrene monomer, methyl methacrylate monomer, vinylidene fluoride monomer, and acrylonitrile monomer. The present invention proposes a method for producing a battery separator, comprising the steps of: dropping a substance onto a cellulose nanofibril suspension, mixing and stirring to obtain an oil-water mixture; treating the oil-water mixture with an ultrasonic fracturing device to obtain a Pickering emulsion; dropping the Pickering emulsion onto a mixed solvent of ethanol and water, adding a water-soluble initiator, cooling to room temperature after the reaction is complete, and then filtering through a filter to obtain a polymer composite emulsion; mixing the polymer composite emulsion with an inorganic substance to obtain a coating slurry; and coating the coating slurry onto a substrate film and baking to obtain a battery separator. 【0011】 Preferably, the cellulose nanofibril suspension comprises one or more of the following: absorbent cotton, paper pulp, wood pulp, and hemp. Preferably, the inorganic substance includes one or more of the following: barium titanate, alumina, silica, and titanium dioxide. 【0012】 Preferably, the heating temperature after mixing the vegetable oil, the N-methylethanolamine, and the catalyst is 50-80°C, and the reaction time is 8 hours; the heating temperature after mixing the vegetable oil-based precursor and the anhydrous is 60-80°C, and the reaction time is 8-12 hours; and the stirring time for mixing the vegetable oil-based acrylate monomer, the peroxybenzoic acid, and the sodium carbonate is 12 hours. 【0013】 Preferably, the ultrasonic crushing apparatus has a processing power of 600 to 800 watts and a processing time of 10 to 15 minutes, and is characterized by dropping the Pickering emulsion into the mixed solvent, then adding the water-soluble initiator, and polymerizing at 60 to 80°C for 2 to 4 hours. 【0014】 Preferably, the oil-water ratio of the oil-water mixture is 1:4 to 8. Preferably, the water-soluble initiator includes one or more of ammonium persulfate, potassium persulfate, and peroxides. Preferably, after applying the coating slurry to the substrate film, it is baked at 60-90°C for 0.5-3 minutes. 【0015】 In this disclosure, a vegetable oil-based acrylate monomer is synthesized using vegetable oil as a raw material. Methacrylate monomer, vinylidene fluoride monomer, acrylonitrile monomer, acrylamide monomer, and styrene monomer are added in predetermined proportions, and the mixture is dispersed and polymerized using cellulose nanofibrils as a stabilizer, a mixture of ethanol and water as a dispersant, and azobisisobutyronitrile as an initiator. This manufacturing method is more environmentally friendly than conventional manufacturing methods. Next, the manufactured multilayer polymer microparticles are blended with barium titanate, the blended slurry is directly coated onto a substrate film, and then baked in an oven. During the baking process, a density difference exists between the barium titanate and the polymer microparticles, causing the denser barium titanate to settle and the polymer microparticles to float. As a result, the manufactured battery separator has excellent heat resistance and high adhesion. Furthermore, since only one coating is required in the manufacturing process, energy consumption and costs are significantly reduced compared to the currently commonly used two-coating method. Furthermore, the battery separator proposed in this invention is suitable for hot-press processes used by various battery manufacturers and maintains adhesive strength to the electrode plate over hot-press temperatures ranging from 25 to 150°C. [Brief explanation of the drawing] 【0016】 [Figure 1] This is a schematic diagram of a battery separator in one embodiment of the present invention. [Figure 2] This is a schematic diagram of polymer fine particles in one embodiment of the present invention. [Figure 3] This is a flowchart of a method for manufacturing a battery separator in one embodiment of the present invention. [Modes for carrying out the invention] 【0017】 Specific embodiments of the present invention will be described in detail below with reference to the drawings. It should be understood that the specific embodiments described herein are for illustrative and interpretive purposes only and are not intended to limit the present invention. 【0018】 The endpoints and any values ​​of the ranges disclosed herein should be understood to include values ​​close to those exact ranges or values, rather than being limited to those exact ranges or values. For numerical ranges, one or more new numerical ranges can be obtained by combining the endpoint values ​​of each range, the endpoint values ​​of each range with individual point values, and the individual point values, and these numerical ranges are deemed to be specifically disclosed herein. 【0019】 Referring to Figure 1, Figure 1 is a schematic diagram of a battery separator in one embodiment of the present invention. The battery separator 100 includes at least one base film 1, at least one inorganic layer 2, and a plurality of polymer fine particles 3. In one embodiment of the present invention, the polymer fine particles 3 are spherical. The inorganic layer 2 is located between the base film 1 and the plurality of polymer fine particles 3. The polymer fine particles 3 have a multilayer structure, and the density of the polymer fine particles 3 is lower than the density of the inorganic layer 2. Preferably, the base film 1 may be made of polypropylene, and the inorganic layer 2 may contain one or more of barium titanate, alumina, silica, and titanium dioxide. 【0020】 Referring to Figure 2, which is a schematic diagram of polymeric microparticles in one embodiment of the present invention, the polymeric microparticles 3 are a polymer. The polymeric microparticles 3 may include one or more of the following: a polyacrylonitrile layer 31, a polystyrene layer 32, a polyvinylidene fluoride layer 33, a polymethyl methacrylate layer 34, and a polyacrylamide layer 35. In one embodiment of the present invention, the polymeric microparticles 3 include, in order from the inside out, a polyacrylonitrile layer 31, a polystyrene layer 32, a polyvinylidene fluoride layer 33, a polymethyl methacrylate layer 34, a polyacrylamide layer 35, a vegetable oil layer 36, and a plurality of cellulose nanofibrils 37. Preferably, the vegetable oil layer 36 may include one or more of the following: sunflower seed oil, Chinese tallow tree seed oil, olive oil, rubber seed oil, castor oil, tung oil, and palm oil, and the cellulose nanofibrils may include one or more of the following: absorbent cotton, paper pulp, wood pulp, and hemp. 【0021】 Referring to FIG. 3, FIG. 3 is a flowchart of a method for manufacturing a battery separator according to an embodiment of the present invention. Hereinafter, the manufacturing method will be described in detail. 【0022】 In step S1, first, a vegetable oil-based acrylate epoxy monomer is manufactured. 8 to 20 parts of vegetable oil, 1 to 4 parts of N-methylethanolamine, and 0.1 to 1 part of a catalyst are mixed, sealed, heated to 50 to 80 ° C, and reacted for 8 hours. Next, unreacted substances and the catalyst are removed to obtain a vegetable oil-based precursor. 8 to 20 parts of the vegetable oil-based precursor and 2 to 15 parts of an anhydride are mixed, sealed, heated to 60 to 80 ° C, and reacted for 8 to 12 hours. After that, unreacted substances are removed to obtain a vegetable oil-based acrylate monomer. Further, 8 to 20 parts of the vegetable oil-based acrylate monomer, 2 to 5 parts of peroxybenzoic acid, and 5 to 10 parts of sodium carbonate are mixed, sealed, and stirred at room temperature for 12 hours. Then, unreacted substances are removed to obtain a vegetable oil-based acrylate epoxy monomer. 【0023】 In step S2, a polymer composite emulsion and a coating slurry are manufactured. 8 to 20 parts of a vegetable oil-based acrylate epoxy monomer, 1 to 8 parts of styrene monomer, 1 to 3 parts of methyl methacrylate, 2 to 5 parts of vinylidene fluoride monomer, and 3 to 5 parts of acrylonitrile monomer are mixed and dropped into 40 to 400 parts of a cellulose nanofibril suspension, and stirred uniformly to obtain an oil-water mixture. Next, it is treated with an ultrasonic crushing device with a power of 600 to 800 watts for 10 to 15 minutes to obtain a Pickering emulsion. 60 to 80 parts of the Pickering emulsion are dropped into a mixed solvent of ethanol and water, and 0.2 to 0.4 parts of a water-soluble initiator are added. Preferably, the water-soluble initiator may contain one or more of ammonium persulfate, potassium persulfate, and peroxides. Next, the mixed solution is put into a thermostat and polymerized at 60 to 80 ° C for 2 to 4 hours. After the reaction is completed, the temperature is lowered to room temperature, and filtered through a nylon filter screen of 100 to 300 meshes to obtain a polymer composite emulsion. Preferably, the oil-water ratio of the oil-water mixture is 1:4 to 8. Finally, 10 to 30 parts of the polymer composite emulsion and 70 to 90 parts of barium titanate are blended to obtain a coating slurry. 【0024】 In another embodiment of the present invention, the proportion of the compounding components may be 0.1 to 2 parts of cellulose nanofibrils, 3 to 7 parts of vegetable oil polymer, 1 to 3 parts of polystyrene, 3 to 6 parts of polymethyl methacrylate, 1 to 5 parts of polyvinylidene fluoride, 1 to 3 parts of polyacrylonitrile, 1 to 4 parts of polyacrylamide, and 70 to 89.9 parts of barium titanate, and the total of the compounding components is 100 parts. In another embodiment of the present invention, the solid content of the cellulose nanofibrils is 0.1 wt% to 1 wt%. 【0025】 In step S3, a battery separator is manufactured. 1 to 3 parts of the coating slurry is uniformly coated on the base film 1 by roll coating, and then put into a blowing oven at 60 to 90 °C and baked for 0.5 to 3 minutes to obtain a battery separator having both heat resistance and adhesiveness. 【0026】 The manufacturing method of the battery separator in the present disclosure will be illustratively described by the following examples. 【0027】 Example 1 The manufacturing method of the vegetable oil-based acrylate epoxy monomer specifically includes the following steps. 【0028】 (1) Prepare 50 parts by mass of palm oil, purge it with nitrogen gas at 100 °C for 30 minutes, heat the palm oil to 65 °C, then add 8 parts by mass of amino alcohol and 1 part by mass of sodium methoxide solution (5 mol / L), seal and react at 65 °C for 8 hours, inject it into 50 parts by mass of dichloromethane (DCM) to dissolve, then wash with saturated sodium chloride, and further dry with anhydrous magnesium sulfate to obtain a vegetable oil-based precursor. 【0029】 (2) Mix 50 parts of the vegetable oil-based precursor, 15 parts of anhydride, and 0.4 parts of 4-dimethylaminopyridine, seal and heat to 65 °C, react for 8 hours, then inject it into 50 parts of dichloromethane to dissolve, wash with saturated sodium bicarbonate and saturated sodium chloride respectively, then dry with anhydrous magnesium sulfate, and then pass through a basic alumina column to obtain a vegetable oil-based acrylate monomer. 【0030】 (3) Dissolve 50 parts of vegetable oil-based acrylate monomer, 10 parts of sodium carbonate, and 6 parts of hydrogen peroxide dropwise in 50 parts of dichloromethane, stir at room temperature for 8 hours, wash with saturated sodium thiosulfate, saturated sodium bicarbonate, and saturated sodium chloride solutions respectively, dry with anhydrous magnesium sulfate, and then pass through a basic alumina column to obtain vegetable oil-based acrylate epoxy monomer. 【0031】 Example 2 The method for manufacturing a battery separator specifically includes the following steps: (1) Mix 5 parts by mass of vegetable oil-based acrylate epoxy monomer, 2 parts by mass of styrene monomer, 4 parts by mass of methyl methacrylate, 3 parts by mass of vinylidene fluoride, 2 parts by mass of acrylonitrile, and 4 parts by mass of acrylamide monomer prepared in Example 1, and dropwise add to 80 parts by mass of a 0.2 wt% cellulose nanofibril suspension. Mix thoroughly until homogeneous, then treat with a 600 watt ultrasonic crushing device for 10 minutes to obtain Pickering emulsion 1. The stability, particle size, and viscosity parameters of Pickering emulsion 1 are shown in Table 1. 【0032】 (2) Place 50 parts of Pickering emulsion 1 in a constant temperature chamber at 65°C, introduce nitrogen gas to remove oxygen for 30 minutes, then add 0.2 parts of potassium persulfate, a water-soluble initiator, and react for 3 hours. Next, raise the temperature to 80°C and react for 30 minutes, then cool to room temperature, and finally filter through a 100-mesh nylon filter to obtain a polymer composite emulsion. 【0033】 (3) Blend 10 parts of polymer composite emulsion with 90 parts of barium titanate solution (solids content 20 wt%) and mechanically stir for 2 hours to obtain a coating slurry. Next, uniformly coat the film onto a polypropylene substrate using a roll coater and bake in a 60°C oven for 1 minute to obtain a battery separator. 【0034】 Comparative Example 1 The method for manufacturing a battery separator specifically includes the following steps: (1) Mix 5 parts by mass of vegetable oil-based acrylate epoxy monomer, 2 parts by mass of styrene monomer, 4 parts by mass of methyl methacrylate, 3 parts by mass of vinylidene fluoride, 2 parts by mass of acrylonitrile, and 4 parts by mass of acrylamide monomer prepared in Example 1, and dropwise add to 80 parts by mass of a 0.5 wt% cellulose nanofibril suspension. Mix thoroughly until homogeneous, then treat with a 600 watt ultrasonic crushing device for 10 minutes to obtain Pickering emulsion 2. The stability, particle size, and viscosity parameters of Pickering emulsion 2 are shown in Table 1. 【0035】 (2) Place 50 parts of Pickering emulsion 2 in a constant temperature chamber at 65°C, introduce nitrogen gas to remove oxygen for 30 minutes, then add 0.2 parts of potassium persulfate, a water-soluble initiator, and react for 3 hours, raise the temperature to 80°C and react for 30 minutes, cool to room temperature, and then filter through a 100-mesh nylon filter to obtain a polymer composite emulsion. 【0036】 (3) Blend 10 parts of polymer composite emulsion with 90 parts of barium titanate solution (solids content 20 wt%) and mechanically stir for 2 hours to obtain a coating slurry. Next, uniformly coat the film onto a polypropylene substrate using a roll coater and bake in a 60°C oven for 1 minute to obtain a battery separator. 【0037】 Comparative Example 2 The method for manufacturing a battery separator specifically includes the following steps: (1) Mix 5 parts by mass of vegetable oil-based acrylate epoxy monomer, 2 parts by mass of styrene monomer, 4 parts by mass of methyl methacrylate, 3 parts by mass of vinylidene fluoride, 2 parts by mass of acrylonitrile, and 4 parts by mass of acrylamide monomer prepared in Example 1, and dropwise add to 160 parts by mass of a 0.2 wt% cellulose nanofibril suspension. Mix thoroughly until homogeneous, then treat with a 600 watt ultrasonic crushing device for 10 minutes to obtain Pickering emulsion 3. The stability, particle size, and viscosity parameters of Pickering emulsion 3 are shown in Table 1. 【0038】 (2) Place 50 parts of Pickering emulsion 3 in a constant temperature chamber at 65°C, introduce nitrogen gas to remove oxygen for 30 minutes, then add 0.2 parts of potassium persulfate, a water-soluble initiator, and react for 3 hours, raise the temperature to 80°C and react for 30 minutes, cool to room temperature, and then filter through a 100-mesh nylon filter to obtain a polymer composite emulsion. 【0039】 (3) Blend 10 parts of polymer composite emulsion with 90 parts of barium titanate solution (solids content 20 wt%) and mechanically stir for 2 hours to obtain a coating slurry. Next, uniformly coat the film onto a polypropylene substrate using a roll coater and bake in a 60°C oven for 1 minute to obtain a battery separator. 【0040】 Comparative Example 3 The method for manufacturing a battery separator specifically includes the following steps: (1) Mix 5 parts by mass of vegetable oil-based acrylate epoxy monomer, 2 parts by mass of styrene monomer, 4 parts by mass of methyl methacrylate, 3 parts by mass of vinylidene fluoride, 2 parts by mass of acrylonitrile, and 4 parts by mass of acrylamide monomer prepared in Example 1, and dropwise add to 80 parts by mass of a 0.2 wt% cellulose nanofibril suspension. Mix thoroughly until homogeneous, then treat with a 600 watt ultrasonic crushing device for 10 minutes to obtain Pickering emulsion 1. 【0041】 (2) Place 50 parts of Pickering emulsion 1 in a constant temperature chamber at 65°C, introduce nitrogen gas to remove oxygen for 30 minutes, then add 0.2 parts of potassium persulfate, a water-soluble initiator, and react for 3 hours, raise the temperature to 80°C and react for 30 minutes, cool to room temperature, and then filter through a 100-mesh nylon filter to obtain a polymer composite emulsion. 【0042】 (3) 10 parts of polymer composite emulsion are uniformly coated onto a polypropylene substrate film using a roll coater, and baked in an oven at 60°C for 1 minute to obtain a battery separator. 【0043】 Table 1 JPEG0007873740000001.jpg60170 【0044】 Table 2 shows the characteristic parameters of the battery separators manufactured by the methods of Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3. As can be seen from Table 2, the battery separator manufactured by the method of Example 2 had the lowest thermal shrinkage rate and the highest positive electrode adhesive strength. 【0045】 Table 2 JPEG0007873740000002.jpg95170 【0046】 In this disclosure, a vegetable oil-based acrylate monomer is synthesized using vegetable oil as a raw material. Methacrylate monomer, vinylidene fluoride monomer, acrylonitrile monomer, acrylamide monomer, and styrene monomer are added in predetermined proportions, and the mixture is dispersed and polymerized using cellulose nanofibrils as a stabilizer, a mixture of ethanol and water as a dispersant, and azobisisobutyronitrile as an initiator. This manufacturing method is more environmentally friendly than conventional manufacturing methods. Next, the manufactured multilayer polymer microparticles are blended with barium titanate, the blended slurry is directly coated onto a substrate film, and then baked in an oven. During the baking process, a density difference exists between the barium titanate and the polymer microparticles, causing the denser barium titanate to settle and the polymer microparticles to float. As a result, the manufactured battery separator has excellent heat resistance and high adhesion. Furthermore, since only one coating is required in the manufacturing process, energy consumption and costs are significantly reduced compared to the currently commonly used two-coating method. Furthermore, the battery separator proposed in this invention is suitable for hot-press processes used by various battery manufacturers and maintains adhesive strength to the electrode plate over hot-press temperatures ranging from 25 to 150°C. 【0047】 The above description is merely one of several specific embodiments of the present invention and does not limit the invention. Any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and principles of the invention should also be included within the scope of protection of the invention. The technical scope of the invention is not limited to the contents of the specification and must be determined based on the claims.

Claims

[Claim 1] At least one substrate, At least one inorganic layer located on the aforementioned substrate, A battery separator comprising a plurality of polymer fine particles located on the inorganic layer and having a density lower than that of the inorganic layer, The battery separator is characterized in that the polymer fine particles include a polymer derived from a plant oil-based acrylate epoxy monomer. [Claim 2] The battery separator according to claim 1, characterized in that the inorganic layer contains one or more of barium titanate, alumina, silica, and titanium dioxide. [Claim 3] The battery separator according to claim 2, characterized in that the polymer fine particles include one or more of the following: a polyacrylonitrile layer, a polystyrene layer, a polyvinylidene fluoride layer, a polymethyl methacrylate layer, and a polyacrylamide layer. [Claim 4] The battery separator according to claim 3, characterized in that the polymer fine particles have a vegetable oil layer on the outside. [Claim 5] The battery separator according to claim 4, characterized in that the vegetable oil layer contains one or more of the following: sunflower seed oil, Chinese tallow tree seed oil, olive oil, rubber seed oil, castor oil, tung oil, and palm oil. [Claim 6] The battery separator according to claim 4, wherein the polymer fine particles further contain a plurality of cellulose nanofibrils, the plurality of cellulose nanofibrils are located outside the vegetable oil layer, and a portion of the plurality of cellulose nanofibrils are connected to the inorganic layer. [Claim 7] The battery separator according to claim 6, characterized in that the cellulose nanofibril includes one or more of the following: absorbent cotton, paper pulp, wood pulp, and hemp. [Claim 8] The steps include: mixing vegetable oil, N-methylethanolamine, and a catalyst, sealing the mixture, and heating it to obtain a vegetable oil-based precursor; The steps include: mixing the aforementioned vegetable oil-based precursor with an anhydrous substance, sealing the mixture, and heating it to obtain a vegetable oil-based acrylate monomer; The steps include: mixing the aforementioned vegetable oil-based acrylate monomer, peroxybenzoic acid, and sodium carbonate, then sealing the mixture and stirring it at room temperature to obtain a vegetable oil-based acrylate epoxy monomer; The steps include: uniformly mixing the aforementioned vegetable oil-based acrylate epoxy monomer, styrene monomer, methyl methacrylate monomer, vinylidene fluoride monomer, and acrylonitrile monomer, dropping them onto a cellulose nanofibril suspension, mixing and stirring to obtain an oil-water mixture, and then treating the oil-water mixture with an ultrasonic disruption device to obtain a Pickering emulsion; The Pickering emulsion is added dropwise to a mixed solvent of ethanol and water, a water-soluble initiator is added, the reaction is completed, the temperature is lowered to room temperature, and then the mixture is filtered through a filter to obtain a polymer composite emulsion. The steps include mixing the polymer composite emulsion with an inorganic substance to obtain a coating slurry, A method for producing a battery separator, comprising the steps of: applying the coating slurry onto a substrate film and baking it to obtain a battery separator. [Claim 9] The method for producing a battery separator according to claim 8, characterized in that the cellulose nanofibril suspension contains one or more of the following: absorbent cotton, paper pulp, wood pulp, and hemp. [Claim 10] The method for producing a battery separator according to claim 8, characterized in that the inorganic substance includes one or more of barium titanate, alumina, silica, and titanium dioxide. [Claim 11] The method for producing a battery separator according to claim 8, characterized in that the heating temperature after mixing the vegetable oil, the N-methylethanolamine, and the catalyst is 50 to 80°C and the reaction time is 8 hours, the heating temperature after mixing the vegetable oil-based precursor and the anhydrous is 60 to 80°C and the reaction time is 8 to 12 hours, and the stirring time for mixing the vegetable oil-based acrylate monomer, the peroxybenzoic acid, and the sodium carbonate is 12 hours. [Claim 12] The method for producing a battery separator according to claim 11, characterized in that the ultrasonic crushing apparatus has a processing power of 600 to 800 watts and a processing time of 10 to 15 minutes, and the Pickering emulsion is dropped into the mixed solvent, then the water-soluble initiator is added, and polymerization is carried out at 60 to 80°C for 2 to 4 hours. [Claim 13] The method for manufacturing a battery separator according to claim 8, characterized in that the oil-water ratio of the oil-water mixture is 1:4 to 8. [Claim 14] The method for producing a battery separator according to claim 8, characterized in that the water-soluble initiator comprises one or more of ammonium persulfate, potassium persulfate, and peroxide. [Claim 15] The method for manufacturing a battery separator according to claim 12, characterized in that the coating slurry is applied to the substrate film and then baked at 60 to 90°C for 0.5 to 3 minutes.

Images