Composite isolation membrane and method for manufacturing the same

Abstract

To provide a composite isolation membrane having high temperature stability, and a method for manufacturing the same.SOLUTION: A composite isolation membrane includes a polyolefin porous substrate and an inorganic coating layer coated on at least one surface of the polyolefin porous substrate. The inorganic coating layer includes a plurality of inorganic particles and a binder resin composition. The binder resin composition includes acrylonitrile-acrylamide-acrylate polymer having a glass transition temperature of less than 0°C, and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C. The composite isolation membrane has good high-temperature resistance.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composite separator, and particularly to a composite separator having high-temperature stability.

Background Art

[0002] With the booming development in the fields of consumer electronics products, wearable devices, electric vehicles, industrial energy storage, etc., the demand for the safety and energy density of lithium-ion batteries is increasing day by day. As an important insulating porous material in the battery, the separator also needs to further improve its physical properties. In order to further ensure the safety of lithium-ion batteries, the separator for lithium-ion batteries needs to improve its high-temperature resistance and reduce the thermal shrinkage rate at high temperatures so as to prevent thermal runaway caused by the mutual contact of electrodes during abnormal application.

[0003] The separator of a lithium-ion battery is based on a polyolefin material, that is, polyethylene (PE) / or polypropylene (PP). It is mainly divided into two types of methods: dry stretching and wet stretching. These two types of methods basically melt the polymer through an extrusion process to form a film, and then produce suitable pores by a stretching method. The dry separator is generally thick and can be produced by multi-layer lamination, so it has high power output, high safety, and low cost. On the other hand, the wet separator is thin, has a high porosity, and high pore size uniformity. Therefore, it is suitable for reducing its thermal shrinkage rate and providing safety by applying a ceramic coating layer on the surface of the polyolefin substrate to form a composite separator. However, when using a resin adhesive to bond ceramic particles, the resin adhesive is prone to strength reduction at high temperatures, and further structural destruction and thermal decomposition occur, and the shrinkage resistance of the composite separator is significantly reduced. Although it is known to increase the thickness of the ceramic coating layer to enhance the thermal shrinkage resistance of the composite separator, in the trend of thinning the separator, the thinned ceramic coating layer cannot resist the significant shrinkage of the porous base film at high temperatures, and the whole shrinks and cannot meet the thermal shrinkage resistance at high temperatures. For example, at 150°C, it cannot reach the requirement of <5%. Therefore, the thinned ceramic coating layer may raise concerns about the safety in use due to the decrease in heat resistance.

Summary of the Invention

[0004] The present invention discloses a composite separator, and particularly discloses a composite separator having high-temperature stability.

[0005] The composite separator according to the present invention includes a polyolefin porous substrate and an inorganic coating layer applied on at least one surface of the polyolefin porous substrate. The inorganic coating layer includes a plurality of inorganic particles and a binder resin composition. The binder resin composition is 2 to 10 parts by weight with respect to 100 parts by weight of the inorganic particles. The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0006] In the inorganic coating layer of the composite separator membrane according to the present invention, the binder resin composition includes 40 wt% to 85 wt% of an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and 15 wt% to 60 wt% of an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0007] In the composite separator membrane according to the present invention, the glass transition temperature of the acrylonitrile-acrylamide-acrylate copolymer is -40°C to 0°C.

[0008] In one embodiment of the composite separator membrane according to the present invention, the inorganic particles used in the inorganic coating layer are Mg(OH) 2 , BaSO 4 , BaTiO 3 , HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al(OH) 3 , Al 2 O 3 , boehmite (AlOOH), SiC, TiO 2 , or a combination thereof.

[0009] In one embodiment of the composite separator membrane according to the present invention, the average particle size (D50) of the inorganic particles in the inorganic coating layer is 0.1 μm to 2.0 μm.

[0010] In one embodiment of the composite separator membrane according to the present invention, the inorganic coating layer can use two or more kinds of inorganic particles having the same particle size or different particle sizes.

[0011] In one embodiment of the composite separator membrane according to the present invention, the thickness of the inorganic coating layer is 0.1 μm to 5.0 μm.

[0012] After the composite separator membrane according to the present invention is heated at 150°C for 1 hour, the heat shrinkage rate is 2% or less in both the longitudinal direction (MD) and the transverse direction (TD).

[0013] The peel strength between the inorganic coating layer and the polyolefin porous substrate in the composite separator membrane according to the present invention is greater than 30 gf / cm.

[0014] In another aspect of the present invention, a method for manufacturing a composite separator membrane is disclosed. It includes the following steps: providing a polyolefin porous substrate, applying a slurry containing a plurality of inorganic particles and a binder resin composition to one or two surfaces of the polyolefin porous substrate, and drying the slurry to form an inorganic coating layer. The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0015] The composite separator membrane according to another embodiment of the present invention includes a polyolefin porous substrate and an inorganic coating layer applied to at least one surface of the porous substrate. The inorganic coating layer includes a plurality of inorganic particles, a binder resin composition, and a photoreactive agent. The binder resin composition is 2 to 10 parts by weight based on 100 parts by weight of the inorganic particles. The photoreactive agent is 0.1 to 1.5 parts by weight based on 100 parts by weight of the inorganic particles. Here, the binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0016] The photoreactive agent used in the inorganic coating layer of the composite separator membrane according to the present invention is 2-isopropylthioxanthone, thioxanthone, a thioxanthone derivative, or a combination thereof.

[0017] The present invention discloses a method for manufacturing a composite separator membrane according to another embodiment, including the following steps: providing a polyolefin porous substrate, and applying a slurry containing a plurality of inorganic particles, a binder resin composition, water, and a photoreaction solution to one or two surfaces of the polyolefin porous substrate, drying the slurry, and irradiating with ultraviolet rays to form an inorganic coating layer. Here, the binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0018] In the method for manufacturing a composite separator membrane according to the present invention, the photoreaction solution further includes a photoreagent and a solvent. The usage amount of the photoreagent is 0.1 part by weight to 1.5 parts by weight based on 100 parts by weight of the inorganic particles.

[0019] In the method for manufacturing a composite separator membrane according to the present invention, the photoreagent is 2-isopropylthioxanthone, thioxanthone, a thioxanthone derivative, or a combination thereof.

[0020] In the method for manufacturing a composite separator membrane according to the present invention, the solvent is toluene, methanol, methyl methacrylate, ethyl acetate, 1,2-dichloroethane, acetone, water, or a combination thereof.

[0021] The above summary of the invention aims to provide a simplified summary of the present disclosure so that viewers can have a basic understanding of the present disclosure. The summary of the invention here is not a complete summary of the present disclosure and is not intended to indicate important / essential elements of the embodiments of the present invention or to define the scope of the present invention. After referring to the following embodiments, those with ordinary knowledge in the technical field to which the present invention belongs can easily understand the basic gist of the present invention, the technical means employed by the present invention, and the embodiments.

Embodiments for Carrying Out the Invention

[0022] To make the disclosure of the present invention more detailed and complete, embodiments and specific examples of the present invention will be described below. However, this is not the only form for implementing or operating the specific embodiments of the present invention. Each of the embodiments disclosed below may be combined with each other or replaced when beneficial. Also, other embodiments may be added to one embodiment. Further description is not necessary.

[0023] The advantages, features, and implementation methods of the present invention will be described in more detail with reference to exemplary embodiments for easier understanding. Also, the present invention can be implemented in different forms. Therefore, it should be understood that the present invention is not limited to the embodiments described in this specification. On the contrary, the provided embodiments are to convey the scope of the present invention more thoroughly and completely to those with ordinary knowledge in the relevant technical field. The present invention is defined only by the scope of the attached patent application.

[0024] Unless otherwise defined, all terms (including scientific and technical terms) and proper nouns used in the following text have substantially the same meaning as commonly understood by those skilled in the art to which the present invention belongs. For example, terms defined by commonly used dictionaries should be understood to have meanings consistent with the content of the relevant field. Unless explicitly defined in the following text, they should not be understood in an overly idealized or overly formal sense.

[0025] The composite separator according to the present invention includes a polyolefin porous substrate and an inorganic coating layer applied to at least one surface of the polyolefin porous substrate. The inorganic coating layer includes a plurality of inorganic particles and a binder resin composition. The binder resin composition is 2 to 10 parts by weight based on 100 parts by weight of the inorganic particles. The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0026] The composite separator according to the present invention can satisfy the heat shrinkage resistance at high temperatures by resisting the shrinkage of the polyolefin porous base film at high temperatures. For example, in the case of 150°C, the requirement of 2% or less can be achieved. In particular, after the inorganic coating layer is thinned, for example, when the thickness is less than 5 μm, preferably less than 3 μm, the heat shrinkage rate after heating at 150°C for 1 hour is 2% or less in both the machine direction (MD) and the transverse direction (TD). Since it has slight heat shrinkage at high temperatures, it can prevent thermal runaway due to the mutual contact of electrodes during abnormal application and provide good safety performance at high temperatures.

[0027] In the composite separator according to the present invention, the binder resin composition used for the inorganic coating layer includes 40 wt% to 85 wt% of an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C, and 15 wt% to 60 wt% of an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0028] In the composite separator according to the present invention, an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C in the binder resin composition used for the inorganic coating layer can provide a strong adhesive force between the inorganic particles and the porous substrate so as to enhance the adhesion between interfaces and the high-temperature resistance. And depending on its property of low glass transition temperature, a soft inorganic coating layer can be provided. Further, since the binder resin composition contains an amide group-containing polymer having a glass transition temperature of 150°C to 200°C, a rigid network structure can be formed at high temperatures. Thereby, the high-temperature resistance of the inorganic coating layer is provided, it is less affected by the shrinkage of the porous substrate at high temperatures, and the shrinkage resistance at high temperatures can be enhanced. The binder resin composition of the present invention uses components with different glass transition temperatures to avoid the situation where the inorganic coating layer softens too much or is too rigid at high temperatures, resulting in embrittlement and poor adhesiveness. The thermal shrinkage rate of the composite separator according to the present invention after being heated at 150°C for 1 hour is 2% or less in both the longitudinal direction (MD) and the transverse direction (TD). Further, since the binder resin composition according to the present invention provides good adhesiveness with the polyolefin porous substrate, there is sufficient adhesion between the inorganic coating layer and the porous substrate, and its peel strength is greater than 30 gf / cm.

[0029] In a preferred embodiment of the present invention, the binder resin composition of the inorganic coating layer preferably contains 40 wt% to 80 wt% of an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and 20 wt% to 60 wt% of an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0030] In a preferred embodiment of the present invention, the inorganic coating layer contains 2 parts by weight to 8 parts by weight of the binder resin composition with respect to 100 parts by weight of the inorganic particles.

[0031] In the binder resin composition of the composite separator according to the present invention, the acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C is a terpolymer derived from the copolymerization of acrylonitrile monomer, acrylamide monomer and acrylate monomer. In a preferred embodiment, the glass transition temperature of the acrylonitrile-acrylamide-acrylate copolymer is -40°C to 0°C. As the acrylonitrile-acrylamide-acrylate copolymer suitable for the present invention, commercially available products such as BM-950B manufactured by Nippon Zeon Co., Ltd. can be used.

[0032] In the binder resin composition of the composite separator according to the present invention, the amide group-containing polymer having a glass transition temperature of 150°C to 200°C may be poly(N-vinylacetamide), amide-(meth)acrylic acid copolymer, acrylonitrile-acrylamide-(meth)acrylate copolymer, etc. As the amide group-containing polymer suitable for the present invention and having a glass transition temperature of 150°C to 200°C, commercially available products such as PNVA GE 191 series (for example, GE191-103, GE191-104, GE191-107 or GE191-108) manufactured by Showa Denko KK, SF168L manufactured by Shenzhen Research Institute of New Materials Co., Ltd., China, and GR506 manufactured by Hunan Gaorui Power Materials Co., Ltd. can be selected.

[0033] In the composite separator according to the present invention, the inorganic particles used for the inorganic coating layer may be those generally used in the technical field. That is, inorganic particles having heat resistance and electrical insulation properties and being stable to electrolytes may be adopted, and there is no particular limitation. Suitable inorganic particles are Mg(OH) 2 , BaSO 4 , BaTiO 3 , HfO 2 , SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al(OH) 3 , Al2 O 3 , boehmite (AlOOH), SiC, TiO 2 , or a combination thereof, particularly Al 2 O 3 , boehmite (AlOOH), SiO 2 , TiO 2 and the like are preferable.

[0034] In the inorganic coating layer of the composite separator according to the present invention, preferably, inorganic particles having a small particle size are used. Thereby, the contact area with the adhesive is increased, and the adhesive force between the two is enhanced. In addition, since the size of the gap formed between the inorganic particles affects the battery characteristics, if the particle size of the inorganic particles is too large, the gap between the particles is too large, and there is a possibility that a short circuit due to lithium dendrites is likely to occur. Therefore, the average particle size (D50) of the inorganic particles is 0.1 μm to 2.0 μm, preferably 0.2 μm to 1.0 μm. In a preferred embodiment of the present invention, the inorganic coating layer can use two or more kinds of inorganic particles having the same or different particle sizes.

[0035] The inorganic coating layer of the composite separator according to the present invention further includes a surfactant for enhancing the interfacial affinity between the inorganic coating layer and the polyolefin porous substrate. As a wetting agent suitable for the present invention, a silicone-based surfactant may be used. The amount of the surfactant used is 0.1 part by weight to 1.5 parts by weight with respect to 100 parts by weight of the inorganic particles, preferably 0.1 part by weight to 1.0 part by weight with respect to 100 parts by weight of the inorganic particles.

[0036] The polyolefin porous substrate used for the composite separator according to the present invention may be a single-layer or multi-layer polyolefin porous substrate, such as single-layer polyethylene, single-layer polypropylene, two-layer polyethylene / polypropylene, or three-layer polypropylene / polyethylene / polypropylene, but is not limited thereto. The thickness of the polyolefin porous substrate suitable for the present invention is about 5 μm to 30 μm, preferably 5 μm to 20 μm, and the porosity is about 40% to 70%, preferably 43% to 65%.

[0037] The composite separator according to the present invention can have an inorganic coating layer applied to one or both sides of a polyolefin porous substrate. The thickness of the inorganic coating layer of the composite separator according to the present invention is a ceramic coating layer on one or both sides with a thickness of 0.5 μm to 5 μm, preferably 0.5 μm to 3 μm, preferably coating layers on both sides.

[0038] Thereby, the adhesion at the interface between the polyolefin porous substrate and the inorganic coating layer in the composite separator can be enhanced, the thermal shrinkage of the separator can be strengthened, and moreover, the concern about battery safety due to peeling at the interface during the charge and discharge process of the inorganic coating layer can be eliminated. In a preferred embodiment of the composite separator according to the present invention, after thinning the inorganic coating layer, for example, when the thickness is less than 5 μm, preferably less than 3 μm, the peel strength between the inorganic coating layer and the porous substrate is greater than 30 gf / cm.

[0039] In the inorganic coating layer of the composite separator according to the present invention, additives such as an antistatic agent, a flame retardant, an antioxidant, or a surface modifier may be further included as required.

[0040] In another aspect of the present invention, a method for manufacturing a composite separator is disclosed, including the following steps: providing a polyolefin porous substrate, applying a slurry containing a plurality of inorganic particles, a binder resin composition, and water to one or two surfaces of the polyolefin porous substrate so as to form an inorganic coating layer, and drying the slurry to form the inorganic coating layer. The inorganic coating layer includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0041] In the method for manufacturing a composite separator according to the present invention, the slurry further includes a dispersant. The dispersant is an alkanolamine-based dispersant, an acrylic ammonium-based dispersant, or a combination thereof. The amount of the dispersant used is 0.1 part by weight to 1.5 parts by weight with respect to 100 parts by weight of the inorganic particle system.

[0042] In the method for manufacturing the composite separator according to the present invention, the inorganic coating layer of the polyolefin porous substrate can be coated using a method known in the art, but is not particularly limited. For example, coating methods generally used in the art such as roll coating method, doctor coating method, dip coating method, roller coating method, spin coating method, slit coating method, etc. can be used.

[0043] In another embodiment of the composite separator according to the present invention, it includes a polyolefin porous substrate and an inorganic coating layer applied to at least one surface of the porous substrate. The inorganic coating layer includes a plurality of inorganic particles, a binder resin composition, and a photoreactive agent. The binder resin composition is 2 to 10 parts by weight with respect to 100 parts by weight of the inorganic particles. The photoreactive agent is 0.1 to 1.5 parts by weight per 100 parts by weight of the inorganic particles. The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C. The photoreactive agent in the inorganic coating layer can cause a radical reaction and cross-linking of the hydrogen-containing carbon bonds on the surface of the polyolefin porous substrate and inside the adhesive resin composition of the inorganic coating layer by irradiation with ultraviolet light, and further strengthen the high-temperature puncture resistance and high-temperature melting integrity of the composite separator without affecting the adhesion between the inorganic coating layer and the polyolefin porous substrate.

[0044] The photoreactive agent used in the inorganic coating layer of the composite separator according to the present invention is 2-isopropylthioxanthone, thioxanthone, thioxanthone derivatives, or a combination thereof.

[0045] Another embodiment of the present invention discloses a method for manufacturing another composite separator membrane, including the following steps: providing a polyolefin porous substrate, and applying a slurry containing a plurality of inorganic particles, a binder resin composition, water, and a photoreaction solution to one or two surfaces of the polyolefin porous substrate, drying the slurry, and irradiating with ultraviolet light to form an inorganic coating layer. Here, the binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

[0046] In the method for manufacturing a composite separator membrane according to the present invention, the photoreaction solution further includes a photoreagent and a solvent. The usage amount of the photoreagent is 0.1 part by weight to 1.5 parts by weight based on 100 parts by weight of the inorganic particles.

[0047] In the method for manufacturing a composite separator membrane according to the present invention, the photoreagent is 2-isopropylthioxanthone, thioxanthone, a thioxanthone derivative, or a combination thereof.

[0048] In the method for manufacturing a composite separator membrane according to the present invention, the solvent is toluene, methanol, methyl methacrylate, ethyl acetate, 1,2-dichloroethane, acetone, water, or a combination thereof.

[0049] The following examples are for further explaining the present invention, but the content of the present invention is not limited thereto.

[0050] Examples

[0051] The following are the raw materials used in the examples of the present invention: SA0-030EN alumina, particle size dimension (D50) 0.52 μm, purchased from China Shandong Guoci Functional Materials Co., Ltd. AM-BL_03 boehmite, particle size dimension (D50) 0.35 μm, purchased from China Shandong Wantai New Materials Technology Co., Ltd. BM-950B acrylonitrile-acrylamide-acrylate copolymer-containing emulsion, solid content 39%, glass transition temperature -30°C, purchased from Nippon Zeon Co., Ltd. GE191-103 poly(N-ethyleneacetamide)-containing emulsion, solid content 10%, glass transition temperature 172°C, purchased from Showa Chemical Industry Co., Ltd., Japan SF168L acrylonitrile-acrylamide-acrylate polymer-containing emulsion, solid content 12.5%, glass transition temperature 180°C, purchased from Shenzhen Research Institute of New Materials Co., Ltd., China GR-506 amide-containing polyacrylate polymer-containing emulsion, solid content 20%, glass transition temperature 192°C, purchased from Hunan Gaorui Power Materials Co., Ltd., China BYK-154 ammonium polyacrylate dispersant, solid content 42%, purchased from BYK, Germany Angus Voltan 100 isoalcohol amine dispersant, purchased from ANGUS Chemical Co., USA BYK-ET-3061 polyether-modified silicone surfactant, purchased from BYK, Germany BYK-ET-3032 styrene-maleic acid dispersant, solid content 40%, purchased from BYK, Germany DOUBLECURE-ITX 2-isopropylthioxanthone, purchased from Taiwan Double Bond Chemical Industry

[0052] Example 1

[0053] 100 g of alumina (SA0-030EN), 4.49 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 22 g of poly(N-ethyleneacetamide)-containing emulsion (GE191-103), 0.95 g of ammonium polyacrylate dispersant (BYK-154) and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water and mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0054] The obtained inorganic particle slurry was coated on both sides of a polyethylene porous substrate with a thickness of 9.2 μm (porosity 48%), and dried to form an inorganic coating layer on the porous substrate, thereby obtaining a composite separation membrane with a thickness of 12.3 μm.

[0055] The obtained composite separation membrane was measured by the measurement method described below. The measurement results are shown in Table 1.

[0056] Thickness measurement: Based on the measurement standard of GB / T 6672-2001, measurement was carried out using a film thickness gauge (VL-50-B, purchased from Mitutoyo, Japan). Measurement was carried out using a flat probe with a diameter of 3 mm and a downward pressure probe load of 0.01 N.

[0057] Air permeability (Gurley) measurement: The separation membrane to be measured was cut into a size of 1 square inch based on the ASTM D-726 standard, and the Gurley air permeability meter was used to measure the time required for 100 c.c. of air to pass through the separation membrane to be measured, thereby obtaining the air permeability.

[0058] Thermal shrinkage measurement: A 10×10 cm sample was cut out, and the initial lengths M0 and T0 in the longitudinal direction (MD) and transverse direction (TD) were marked at the center position of the sample before measurement. After marking, the sample was sandwiched between two A4 papers and placed in an oven, heated at 150 °C for 1 hour. After heating, the sample was left to stand for 30 minutes in the same environment as the measuring instrument, and the lengths M1 in the longitudinal direction (MD) and T1 in the transverse direction (TD) at the center position of the sample were measured. Longitudinal direction (MD) thermal shrinkage rate = (M0 - M1) / M0 × 100% Transverse direction (TD) thermal shrinkage rate = (T0 - T1) / T0 × 100%

[0059] Mechanical strength measurement: Based on the ASTM D882-09 standard, the separation membranes to be measured were each cut into a size of 10 mm in width and ≧150 mm in length in the longitudinal direction (MD) and transverse direction (TD), and pulled at a speed of 500 mm / min using a universal tensile machine. After obtaining the maximum load value when the sample broke, it was divided by the cross-sectional area of the separation membrane (sample width × substrate thickness) to calculate the elongation strength in the longitudinal direction (MD) and transverse direction (TD) of the separation membrane respectively.

[0060] Peeling strength: After cutting an adhesive sheet with a thickness of 80 μm (model number 31B, purchased from Nitto Denko) into a size of 60 mm in length and 20 mm in width, it was attached to the composite separator, and the adhesive sheet was peeled off at a speed of 180° and 50 mm / min using a universal tensile machine, and the peeling force of a 50 mm length in the middle stage was collected. After measuring 5 test pieces for each composite separator, the average peeling strength was obtained.

[0061] Impedance measurement: After cutting the separator into a circle with a diameter of 24 mm, it was immersed in a standard electrolyte (LiPF6 solution with a concentration of 1 M, solvent weight ratio EC / DMC / EMC = 1 / 1 / 1) for 12 hours to completely penetrate the electrolyte into the separator, and then the separator was placed between two electrodes, and the impedance was measured between a frequency of 1000 and 200000.

[0062] Example 2

[0063] 100 g of alumina (SA0-030EN), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 13 g of poly(N-ethyleneacetamide)-containing emulsion (GE191-103), 1.55 g of ammonium polyacrylate dispersant (BYK-154), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water and mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0064] The obtained inorganic particle slurry was coated on both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, and a composite separator with a thickness of 12.6 μm was obtained.

[0065] The obtained composite separator was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0066] Example 3

[0067] 100 g of alumina (SA0-030 EN), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 5.0 g of amide-containing polyacrylate polymer emulsion (GR-506), 1.43 g of ammonium polyacrylate dispersant (BYK-154), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0068] The obtained inorganic particle slurry was coated on both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, obtaining a composite separation membrane with a thickness of 12.4 μm.

[0069] The obtained composite separation membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0070] Example 4

[0071] 100 g of alumina (SA0-030 EN), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 12 g of amide group-containing polymer emulsion (SF168L), 0.40 g of styrene-maleic acid dispersant (BYK-ET-3032), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0072] The obtained inorganic particle slurry was coated on both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, obtaining a composite separation membrane with a thickness of 12.2 μm.

[0073] The obtained composite separation membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0074] Example 5

[0075] 100 g of alumina (SA0-030EN), 6.92 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 12 g of amide group-containing polymer emulsion (SF 168 L), 0.55 g of isoalcohol amine dispersant (Angus Voltan 100), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0076] The obtained inorganic particle slurry was applied to both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, obtaining a composite separation membrane with a thickness of 12.3 μm.

[0077] The obtained composite separation membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0078] Example 6

[0079] 75 g of alumina (SA0-030EN), 25 g of boehmite (AM-BL-03), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 13 g of poly(N-ethyleneacetamide)-containing emulsion (GE191-103), 0.95 g of ammonium polyacrylate dispersant (BYK-154), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0080] The obtained inorganic particle slurry was applied to both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, obtaining a composite separation membrane with a thickness of 12.7 μm.

[0081] The obtained composite separation membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0082] Example 7

[0083] 50 g of alumina (SA0-030EN), 50 g of boehmite (AM-BL-03), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 13 g of poly(N-ethyleneacetamide)-containing emulsion (GE191-103), 0.95 g of ammonium polyacrylate dispersant (BYK-154), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred to obtain an inorganic particle slurry.

[0084] The obtained inorganic particle slurry was coated on both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate, obtaining a composite separation membrane with a thickness of 12.8 μm.

[0085] The obtained composite separation membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0086] Example 8

[0087] 100 g of alumina (SA0-030EN), 8.97 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 13 g of poly(N-vinylacetamide)-containing emulsion (GE 191-103), 1.55 g of ammonium polyacrylate dispersant (BYK-154), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water, mixed, and uniformly stirred. A photoreaction solution obtained by uniformly mixing 0.526 g of 2-isopropylthioxanthone and 2.63 g of methyl methacrylate solvent was added, and the mixture was uniformly stirred at room temperature to obtain an inorganic particle slurry.

[0088] The obtained inorganic particle slurry was coated on both sides of a polyethylene porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate. It was then exposed to a UV lamp with a radiation dose of 500 mJ / cm 2 to obtain a composite separation membrane with a thickness of 11.9 μm.

[0089] The obtained composite separator membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0090] Example 9

[0091] 100 g of alumina (SA0-030EN), 6.92 g of acrylonitrile-acrylamide-acrylate-containing emulsion (BM-950B), 12 g of amide group-containing polymer emulsion (SF168L), 0.55 g of isoalcoholamine dispersant (Angus Voltan 100), and 0.5 g of polyether-modified silicone surfactant (BYK-ET-3061) were added to deionized water and mixed, stirred uniformly, and a photoreaction solution obtained by uniformly mixing 0.526 g of 2-isopropylthioxanthone and 2.63 g of methyl methacrylate solvent was added, and stirred uniformly at room temperature to obtain an inorganic particle slurry.

[0092] The obtained inorganic particle slurry was coated on both sides of a porous substrate with a thickness of 9.2 μm (porosity 48%) and dried to form an inorganic coating layer on the porous substrate. Under an air environment, it was exposed with a UV lamp having a radiation dose of 500 mJ / cm 2 to obtain a composite separator membrane with a thickness of 11.9 μm.

[0093] The fabricated composite separator membrane was measured by the measurement method described in Example 1. The measurement results are shown in Table 1.

[0094] Table 1: Measurement results of the characteristics of the separator membrane according to the examples

Table 1

[0095] Although the embodiments of the present invention are disclosed as described above, they are not used to limit the present invention. Any person skilled in this technology can make various changes and refinements without departing from the spirit and scope of the present invention. The protection scope of the present invention is in accordance with that defined by the appended claims.

Claims

1. A composite separator comprising: A polyolefin porous substrate; An inorganic coating layer applied to at least one surface of the polyolefin porous substrate; Including, The inorganic coating layer includes a plurality of inorganic particles and a binder resin composition, and the binder resin composition is in an amount of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the inorganic particles; The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0° C. and an amide group-containing polymer having a glass transition temperature of 150° C. to 200° C. Composite isolation membrane.

2. 2. The composite separator according to claim 1, wherein the binder resin composition comprises: 40 wt % to 85 wt % of an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C; and 15 wt % to 60 wt % of an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

3. 2. The composite separator according to claim 1, wherein the binder resin composition comprises: 40 wt % to 80 wt % of an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C; and 20 wt % to 60 wt % of an amide group-containing polymer having a glass transition temperature of 150°C to 200°C.

4. 2. The composite separator according to claim 1, wherein the acrylonitrile-acrylamide-acrylate copolymer has a glass transition temperature of -40°C to 0°C.

5. 2. The composite separator according to claim 1, wherein the inorganic coating layer has a thickness of 0.1 μm to 5.0 μm.

6. The composite separator according to claim 5, wherein the inorganic coating layer has a thickness of 0.5 μm to 3 μm.

7. 2. The composite separator according to claim 1, wherein the amide group-containing polymer having a glass transition temperature of 150°C to 200°C is poly(N-vinylacetamide), an amide-(meth)acrylic acid copolymer, or an acrylonitrile-acrylamide-(meth)acrylate copolymer.

8. 2. The composite separator of claim 1, wherein the inorganic coating layer further comprises an ammonium salt dispersant in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the inorganic particles.

9. 2. The composite separator of claim 1, wherein the inorganic coating layer further comprises a silicone surfactant in an amount of 0.1 to 1.0 parts by weight based on 100 parts by weight of the inorganic particles.

10. The inorganic particles used in the inorganic coating layer are Mg(OH) ２ , BaSO ４ , BaTiO ３ , HfO ２ , SrTiO ３ , SnO ２ , CeO ２ , MgO, NiO, CaO, ZnO, ZrO ２ , SiO ２ , Y ２ O ３ , Al(OH) ３ , Al ２ O ３ , boehmite (AlOOH), SiC, TiO ２ or a combination thereof.

11. The composite separator according to claim 1, wherein the inorganic particles in the inorganic coating layer have an average particle size (D50) of 0.1 μm to 2.0 μm.

12. 2. The composite separator of claim 1, wherein the inorganic coating layer comprises 2 to 8 parts by weight of the binder resin composition based on 100 parts by weight of the inorganic particles.

13. The composite separator according to claim 1 , wherein the inorganic coating layer further comprises an additive, such as an antistatic agent, a flame retardant, an antioxidant, or a surface modifier.

14. A method for producing a composite separator, comprising the steps of: Providing a polyolefin porous substrate; applying a slurry including a plurality of inorganic particles, a binder resin composition, and water to one or two surfaces of the polyolefin porous substrate to form an inorganic coating layer; Including, The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C, and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C. A method for manufacturing a composite separator.

15. The method for producing a composite separator according to claim 14, wherein the slurry further comprises a dispersant and / or a surfactant.

16. The method for producing a composite separator according to claim 15, wherein the dispersant is an alkanolamine-based dispersant, an ammonium acrylate-based dispersant, or a combination thereof.

17. The method for manufacturing a composite separator according to claim 15, wherein the amount of the dispersant used is 0.1 to 1.0 parts by weight based on 100 parts by weight of the inorganic particles.

18. The method for manufacturing a composite separator according to claim 15, wherein the surfactant is a siloxane-based surfactant.

19. The method for manufacturing a composite separator according to claim 15, wherein the surfactant is used in an amount of 0.1 to 1 part by weight based on 100 parts by weight of the inorganic particles.

20. A composite separator membrane, A polyolefin porous substrate; An inorganic coating layer applied to at least one surface of the polyolefin porous substrate; Including, The inorganic coating layer includes a plurality of inorganic particles, a binder resin composition, and a photoreactive agent, the binder resin composition being used in an amount of 2 parts by weight to 10 parts by weight based on 100 parts by weight of the inorganic particles, and the photoreactive agent being used in an amount of 0.1 parts by weight to 1.5 parts by weight based on 100 parts by weight of the inorganic particles; The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature (Tg) of less than 0°C, and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C. Composite isolation membrane.

21. 21. The composite separator of claim 20, wherein the photoreactor is 2-isopropylthioxanthone, thioxanthone, a thioxanthone derivative, or a combination thereof.

22. A method for producing a composite separator, comprising the steps of: Providing a polyolefin porous substrate; Applying a slurry including a plurality of inorganic particles, a binding resin composition, water, and a photoreactive solution to one or two surfaces of the polyolefin porous substrate; drying the slurry and irradiating it with ultraviolet light to form an inorganic coating layer; Including, The binder resin composition includes an acrylonitrile-acrylamide-acrylate copolymer having a glass transition temperature of less than 0°C, and an amide group-containing polymer having a glass transition temperature of 150°C to 200°C. A method for manufacturing a composite separator.

23. 23. The method of claim 22, wherein the photoreaction solution further comprises a photoreaction agent and a solvent, and the amount of the photoreaction agent is 0.1 to 1.5 parts by weight based on 100 parts by weight of the inorganic particles.

24. 24. The method for preparing a composite separator according to claim 23, wherein the photoreactor is 2-isopropylthioxanthone, thioxanthone, a thioxanthone derivative, or a combination thereof.

25. 24. The method for preparing a composite separator according to claim 23, wherein the solvent is toluene, methanol, methyl methacrylate, ethyl acetate, 1,2-dichloroethane, acetone, water, or a combination thereof.

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