KR20140082261A - Tri-layered separator, electrochemical device comprising the same, and method of preparing the separator - Google Patents

Abstract

The present invention relates to a tri-layered separator, an electrochemical device including the same, and a method of preparing the separator. According to one aspect of the present invention, provided is a tri-layered electrochemical separator including a lamination member having a first non-fabric layer, a porous polyolefin film, and a second non-fabric layer sequentially laminated on each other, and a porous coating layer including the mixture of inorganic particles and a binder and coated on one surface of the first non-fabric layer, one surface of the second non-fabric layer, or both surfaces of the first and second non-fabric layers, which do not make contact with the porous polyolefin film, an electrochemical device including the same, such as a lithium secondary battery. According to another aspect of the present invention, provided is a method of fabricating the electrochemical device separator, which includes the steps of preparing the non-fabric layer; preparing the porous polyolefin film, forming the lamination layer, forming a tri-layered structure, forming a porous coating layer, and forming a tri-layered separator. According to the present invention, as the electrochemical separator is improved in the short, the thermal contraction, and the strength, the stability of the electrochemical device is maintained and the output performance can be significantly improved.

Description

TECHNICAL FIELD The present invention relates to a three-layer separator, an electrochemical device including the same, and a manufacturing method of the separator,

The present invention relates to a three-layered separator, specifically a nonwoven fabric layer, a polyolefin film and a nonwoven fabric layer, an electrochemical device including the same, and a process for producing the separator.

A secondary battery is a chemical battery which can be used semi-permanently by repeatedly charging and discharging by electrochemical reaction, and can be classified into a lead-acid battery, a nickel-cadmium battery, a nickel-hydrogen battery and a lithium secondary battery. Among them, lithium secondary batteries are superior to other batteries in terms of high voltage and energy density characteristics, leading the secondary battery market. Depending on the kind of electrolyte, a lithium ion secondary battery using a liquid electrolyte and a solid electrolyte are used Lithium-ion polymer secondary batteries.

The lithium secondary battery includes an anode, a cathode, an electrolyte and a separator. Among these separators, the separator is required to separate the anode and the cathode from each other and electrically insulate the same, while increasing the permeability of lithium ions based on the high porosity. It is the height.

Polyolefin (PO) films which are advantageous for forming pores and which are excellent in chemical resistance, mechanical properties, and thermal properties and low in cost are mainly used as the polymer base material of the separator which is generally used. However, When the positive electrode and negative electrode of the assembly are short-circuited, the electrolyte in which the lithium salt and the solvent are mixed in the positive electrode is decomposed, lithium metal precipitates in the negative electrode, deteriorating battery characteristics, and internal short-circuiting may occur.

In order to achieve shut-down and thermal stability, a three-layered structure of a tri-layer structure such as polypropylene (PP) -Polyethylene (PE) -Polypropylene (PP) There is a demand for a method of solving the problem of air permeability and heat shrinkage while simultaneously satisfying both shutdown and thermal stability because there is a problem of the air permeability and heat shrinkage thereof as a separator.

On the other hand, when the nonwoven fabric layer is used alone as a separation membrane, ion conductivity and the like are advantageous because of its own property, but there is a disadvantage that stability is poor due to internal short circuit and poor strength. As a production example thereof, there is a technique disclosed in International Publication No. WO 1999/64649 (Tencel Ltd., International Publication, December 16, 1999).

Therefore, there is a continuing need to develop a separator having a new structure in order to reinforce the disadvantages of such a polyolefin film and a nonwoven fabric layer.

A problem to be solved by the present invention is to provide a separator which has advantages of the polyolefin film and the nonwoven fabric layer while eliminating the disadvantages thereof.

In order to achieve the above object, according to one aspect of the present invention, there is provided a laminated body comprising a laminate in which a first nonwoven fabric layer, a porous polyolefin film and a second nonwoven fabric layer are laminated in order, and a first nonwoven fabric layer which is not in contact with the porous polyolefin film A separator for an electrochemical device having a three-layer structure including one surface of the first nonwoven fabric layer, one surface of the second nonwoven fabric layer, or a mixed porous coating layer of inorganic particles and a binder on both surfaces of the second nonwoven fabric layer; And an electrochemical device including the same, for example, a lithium secondary battery.

According to another aspect of the present invention, there is provided a method for producing a porous polyolefin film, comprising the steps of preparing a first nonwoven fabric layer and a second nonwoven fabric layer, preparing a porous polyolefin film, Forming a three-layer structure by rolling the laminate; applying a coating liquid in which inorganic particles are dispersed and the binder is dissolved in a solvent on the outermost upper and bottom surfaces of the formed three-layer structure to form a porous coating layer And removing the solvent from the coated three-layered structure to form a three-layered separator.

According to the present invention, the separation membrane for an electrochemical device can greatly improve the output performance while maintaining the stability of the electrochemical device including the short circuit, heat shrinkage and strength improvement.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given above, serve to better understand the spirit of the invention. And should not be construed as limiting.
1 is a cross-sectional view of a separation membrane for an electrochemical device according to an embodiment of the present invention.
2 is a schematic flow chart of a process for producing a separator for an electrochemical device according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor may designate the concept of a term appropriately in order to describe its own invention in the best way possible. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the constitution described in the embodiments of the present invention is merely an embodiment of the present invention, and does not represent all the technical ideas of the present invention, so that various equivalents and modifications It should be understood.

1 is a cross-sectional view of a separation membrane for an electrochemical device according to an embodiment of the present invention.

Referring to FIG. 1, a separator for an electrochemical device having a three-layer structure according to an embodiment of the present invention includes a porous polyolefin film interposed between a first nonwoven fabric layer and a second nonwoven fabric layer. That is, it is a laminate having a three-layer structure in which a first nonwoven fabric layer, a porous polyolefin film and a second nonwoven fabric layer are laminated in order.

The porous polyolefin film may be made of one or more kinds selected from the group consisting of polyethylene, such as high density polyethylene, linear low density polyethylene, low density polyethylene or ultra high molecular weight polyethylene, polypropylene, polybutylene, , And the polyolefin film may have a porous structure by forming pores by a dry method or a wet method well known in the art.

Such a porous polyolefin film can impart various functions depending on the material thereof as a separation membrane. For example, polypropylene (PP) can be used as the material of the porous polyolefin film. Since the melting point of the polypropylene (PP) is about 165 to 170 占 폚, the structural stability of the separator, that is, the thermal stability, can be kept excellent against heat rise due to internal or external factors of the electrochemical device. In the case of polyethylene (PE), a shutdown function can be imparted to the electrochemical device since the melting point of the polypropylene (PP) is lower than that of the polypropylene (PP), for example, its melting point is approximately 105 to 140 ° C.

The porous polyolefin film can have a thickness of from about 1 to about 20 microns. When this porous polyolefin film has a thickness within the above-mentioned range, it is possible to reduce the risk of shorts which may occur when only a nonwoven fabric is used, and to enhance low membrane strength.

Nonwoven fabrics are defined as having a fabric shape in which the fibrous aggregate is chemically bonded (for example, by blending the adhesive to the fibers), mechanical action or by appropriate moisture and heat treatment, without process by spinning, weaving or knitting . These nonwoven fabrics are used in various fields including electrochemical devices due to their excellent air permeability, warmth and unresolved properties of cut portions. Examples of the method for producing such a nonwoven fabric include a dry method, a wet method, a spun-lamination method, and an electric spraying method.

Examples of the raw material of the nonwoven fabric raw material, that is, the first nonwoven fabric layer and the second nonwoven fabric layer are independently polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, Polyamide, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polyetherketone, polyetheretherketone, polyetheretherketone, But are not limited to, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylenesulfide, polyvinyl alcohol, Polyacrylic acid, polyethylene oxide, polyethylene-polyvinyl < RTI ID = 0.0 > Alcohol copolymer, polyethylene naphthalene (polyethylenenaphthalene) and the like are not limited.

Typically, the physical properties of the nonwoven fabric are determined, for example, in the case of electrospinning, by the properties of the spinning solution (e.g., concentration, viscosity, surface tension, conductivity, viscoelasticity, polarity, etc.), distance from the end of the syringe Voltage, etc.), the spinning time, the spinning speed, the spinning environment, and the like.

Further, the nonwoven fabric layer of the present invention may be formed from a conjugate fiber having a core-sheath structure. The core-sheath nonwoven fabric may be formed by combining the composite fibers in such a manner that all or a part of the sheath portion is fused together. The composite fiber has a core-sheath structure cross section, that is, a core portion and a sheath portion surrounding the core portion. The core portion is a high heat resistant polymer having a relatively high melting point and the sheath portion is a low heat resistant polymer having a lower melting point than the high heat resistant polymer.

The high heat-resistant polymer may be a polypropylene (PP), a polyethylene terephthalate (PET), a polyester, a polyacetal, a polyamide, a polycarbonate, a polyimide, Polyetheretherketone, polyetherimide (PEI), polyamideimide, polyethersulfone (PES), polyphenylene oxide, polyphenylenesulfide, and the like. Polytetrafluoroethylene, polyethylene naphthalene, and the like, but is not limited thereto. Preferably, the high heat-resistant polymer is polypropylene (PP) or polyethylene terephthalate (PET).

The low heat-resistant polymer may be one selected from the group consisting of polyethylene (PE), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylidene fluoride But are not limited to, mixtures of two or more. Preferably, the low heat-resistant polymer is polyethylene (PE).

The first nonwoven layer and the second nonwoven layer may each independently have a thickness of from about 5 to about 60 [mu] m, or from about 10 to about 50 [mu] m. If the first nonwoven layer and the second nonwoven layer have a thickness within the above-mentioned range, problems associated with air permeability and heat shrinkage that may occur when using only the porous polyolefin film can be eliminated.

A mixed porous coating layer of inorganic particles and a binder is applied to one surface of the first non-woven fabric layer that is not in contact with the porous polyolefin film, one surface of the second non-woven fabric layer, or both surfaces.

The inorganic particles can be more advantageous for securing the safety of the electrochemical device by suppressing a short circuit due to foreign matter, thermal runaway, etc. between the anode and the cathode. The inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles usable in the present invention are not particularly limited as long as oxidation and / or reduction reaction does not occur in the operating voltage range of the applied electrochemical device (for example, about 0 to about 5 V based on Li / Li ⁺ ) . Particularly, when inorganic particles having ion transfer ability are used, the ion conductivity in the electrochemical device can be increased to improve the performance. When inorganic particles having a high dielectric constant are used as the inorganic particles, the dissociation of the electrolyte salt, for example, the lithium salt in the liquid electrolyte, can also contribute to enhance the ionic conductivity of the electrolyte.

For the reasons stated above, the inorganic particles may comprise high-permittivity inorganic particles having a dielectric constant of at least about 5, such as at least about 10, inorganic particles having lithium ion transport capability, or mixtures thereof. Non-limiting examples of a dielectric constant of about 5 or more inorganic particles is _{BaTiO 3, Pb (Zr, Ti} ) O 3 (PZT), Pb 1 - x La x Zr 1 - y Ti y O 3 (PLZT), PB (Mg ₃ Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), hafnia (HfO ₂ ), SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , TiO _{2 ,} SiC Or mixtures thereof.

In particular, above a _{BaTiO 3, Pb (Zr, Ti} ) O 3 (PZT), Pb 1 - x La x Zr 1 - y Ti y O 3 (PLZT), PB (Mg 3 Nb 2/3) O 3 -PbTiO ₃ (PMN-PT) and hafnia (HfO ₂ ) exhibit a high permittivity characteristic with a permittivity constant of 100 or more. In addition, when a certain pressure is applied, a charge is generated when being tensioned or compressed. It is possible to prevent internal short-circuiting of both electrodes due to an external impact, thereby improving the safety of the electrochemical device. Further, when the above-mentioned high-permittivity inorganic particles and inorganic particles having lithium ion transferring ability are mixed, their synergistic effect can be doubled.

The inorganic particles having the lithium ion transferring ability refer to inorganic particles that contain a lithium element but do not store lithium but have a function of transferring lithium ions. The inorganic particles having lithium ion transferring ability exist in the particle structure It is possible to transfer and move lithium ions due to a kind of defect, so that the lithium ion conductivity in the battery is improved, thereby improving the performance of the battery. Examples of the inorganic particles having lithium ion transferring ability include lithium phosphate (Li ₃ PO ₄ ), lithium titanium phosphate (Li _x Ti _y (PO ₄ ) ₃ , 0 <x <2, 0 <y < (Li _x Al _y Ti _z (PO ₄ ) ₃ , 0 <x <2, 0 <y <1, 0 <z <3), 14Li ₂ O-9Al ₂ O ₃ -38TiO ₂ -39P ₂ O ₅ as such (LiAlTiP) _x O _y series glass (0 <x <4, 0 <y <13), lithium lanthanum titanate _{(Li x La y TiO 3,} 0 <x <2, 0 <y <3 ), Li _{3 .25} Ge _{0 .25} P _{0 .75} S ₄ Lithium, such as germanium Mani help thiophosphate lithium nitro, such as _{(Li x Ge y P z S} w, 0 <x <4, 0 <y <1, 0 <z <1, 0 <w <5), Li 3 N fluoride _{(Li x N y, 0 <} x <4, 0 <y <2), Li 3 PO 4 -Li 2 S-SiS 2 SiS 2 family, such as _{glass (Li x Si y S z} , 0 <x <3 , 0 <y <2, 0 <z <4), LiI-Li 2 SP 2 S 5 , etc., such as P ₂ S ₅ based _{glass (Li x P y S z} , 0 <x <3, 0 <y <3, 0 < z < 7), or a mixture thereof.

The size of the inorganic particles is not limited, but for the formation of a uniform thickness of coating layer and adequate porosity, the average particle size of the inorganic particles may be as possible as possible from about 0.01 to about 5 탆, or from about 0.05 to about 1.0 탆. When the size of the inorganic particles satisfies the above range, the dispersibility is improved, the physical properties of the separator can be easily controlled, the thickness of the porous coating layer is increased, and the mechanical properties are deteriorated or excessively large, The problem of an internal short circuit can be prevented.

Non-limiting examples of the binder include polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride-co-trichloroethylene ), Polyvinylidene fluoride-co-chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylpyrrolidone, But are not limited to, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate (cellulose acetate propionate), cyanoethylpullulan lan, cyanoethylpolyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose (CMC), acrylic Acrylonitrile-styrene-butadiene copolymer, polyimide, polyvinylidenefluoride, polyacrylonitrile, and styrene butadiene rubber (SBR). , Or a mixture of two or more thereof. The binder is located on part or all of the inorganic particles to connect and fix the inorganic particles.

According to an embodiment of the present invention, the composition ratio of the inorganic particles and the binder in the porous coating layer coated on the separator may be, for example, about 50:50 to about 99: 1, or about 60:40 to about 95: 5. The thickness of the porous coating layer composed of the inorganic particles and the binder is not particularly limited, but may be in the range of about 0.01 to about 20 占 퐉. The pore size and porosity are also not particularly limited, but the pore size may range from about 0.01 to about 10 μm, and the porosity may range from about 5 to about 90%.

The separation membrane according to an embodiment of the present invention may further include other additives in order to improve the function and stability in addition to the inorganic particles and the binder described above as the porous coating layer component.

Thus, a three-layer structure having two nonwoven fabric layers and a polyolefin film sandwiched therebetween can provide effective shutdown and thermal stability together with structural stability.

According to an embodiment of the present invention, there is also provided an electrochemical device including a positive electrode, a negative electrode, and a separation membrane for electrochemical devices interposed between the positive electrode and the negative electrode. The electrochemical device according to one aspect of the present invention includes all devices that perform an electrochemical reaction, and specific examples thereof include capacitors such as all types of primary cells, secondary cells, fuel cells, solar cells, or super capacitor devices ). In particular, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery may be included in the secondary battery.

The electrode to be applied together with the separator according to an aspect of the present invention is not particularly limited, and the electrode active material may be bound to an electrode current collector according to a conventional method known in the art. Examples of the cathode active material include, but are not limited to, lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron oxide, or a combination thereof A lithium complex oxide may be used. As a non-limiting example of the negative electrode active material, a conventional negative electrode active material that can be used for a negative electrode of an electrochemical device can be used. In particular, lithium metal or a lithium alloy, carbon, petroleum coke, activated carbon, Lithium adsorbing materials such as graphite or other carbon-based materials and the like can be used. Non-limiting examples of the positive current collector include aluminum, nickel, or a combination thereof. Examples of the negative current collector include copper, gold, nickel, or a copper alloy or a combination thereof Foil to be manufactured, and the like.

The electrolyte that can be used in the electrochemical device according to one aspect of the present invention is a salt having a structure such as A ⁺ B ^- , where A ⁺ is an alkali metal cation such as Li ⁺ , Na ⁺ , K ⁺ And B ^- is a metal ion such as PF ₆ ^- , BF ₄ ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , AsF ₆ ^- , CH ₃ CO ₂ ^- , CF ₃ SO ₃ ^- , N (CF ₃ SO ₂ ) _{^{2 -, C (CF 2 SO}} 2) 3 - anion, or a salt containing an ion composed of a combination of propylene carbonate (PC) such as, ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC ), Dimethyl carbonate (DPC), dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (G-butyrolactone), or an organic solvent composed of a mixture thereof, but is not limited thereto It is not.

The electrolyte injection may be performed at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and required properties of the final product. That is, it can be applied before assembling the cell or at the final stage of assembling the cell.

As a process for applying a separator according to an aspect of the present invention to a battery, a lamination, stacking and folding process of a separator and an electrode can be performed in addition to a conventional winding process.

2 is a schematic flow chart of a process for producing a separator for an electrochemical device according to an embodiment of the present invention.

According to another aspect of the present invention, there is provided a method of manufacturing a porous polyolefin film, comprising the steps of preparing a nonwoven fabric layer (S1), preparing a porous polyolefin film (S2), forming a laminate (S3) , Forming a porous coating layer (S5), and forming a three-layered separator (S6).

In step S1, a first nonwoven fabric layer and a second nonwoven fabric layer are prepared. Each of these nonwoven layers may be formed of the same or different materials and / or patterns with a nonwoven material as previously described herein using methods customary in the art. Depending on the material used, the binding force of the nonwoven fabric layer itself and the bonding force between the nonwoven fabric layer and the adjacent polyolefin film may vary, which may improve the structural integrity of the nonwoven fabric layer depending on the intrinsic melting point and strength of the material, Can be bonded to the adjacent polyolefin film through a binder, heat fusion, or the like.

For example, the nonwoven fabric layer of the present invention may be formed from a conjugate fiber having a core-sheath structure. The core-sheath nonwoven fabric may be formed by combining the composite fibers in such a manner that all or a part of the sheath portion is fused together. The composite fiber has a core-sheath structure cross section, that is, a core portion and a sheath portion surrounding the core portion. The core portion is a high heat resistant polymer having a relatively high melting point and the sheath portion is a low heat resistant polymer having a lower melting point than the high heat resistant polymer. The high heat resistant polymer and the low heat resistant polymer are as described hereinabove.

The nonwoven fabric layer having such a structure can firmly maintain the layer structure by thermal fusion of the layer itself, and can be a path for transporting the electrolyte through the pores formed therebetween. The nonwoven fabric layer can be bonded to the polyolefin film, Or the like, to form a laminate.

In step S2, a polyolefin film is formed using the polyolefin material as previously described herein, and the pores of the polyolefin film are formed using methods customary in the art. Such conventional methods, such as dry methods for forming pores by uniaxial or biaxial orientation, and wet methods for forming pores by mixing and removing diluents, solvents or pore formers are well known in the art.

In step S3, the first nonwoven fabric layer, the porous polyolefin film, and the second nonwoven fabric layer prepared in steps S1 and S2 are laminated in this order to form a laminate. The first nonwoven fabric layer and the second nonwoven fabric layer may be the same or different from each other in material, thickness, and / or pattern. The methods of lamination can be carried out individually, batchwise or simultaneously.

In step S4, the laminate formed in step S3 is rolled. Such rolling is carried out using methods and equipment customary in the art, whereby the first nonwoven layer, the porous polyolefin film and the second nonwoven layer are laminated in order and rolled.

Also, as mentioned in step S2, the nonwoven fabric such as a core-sheath structure can be easily bonded to the porous polyolefin film by a binder, heat fusion, rolling or the like known in the art.

Through this lamination, bonding, rolling and the like, a three-layer structure having the order of the first nonwoven layer, the porous polyolefin film and the second nonwoven layer is formed.

In step S5, a coating layer is formed on the outermost surface of the three-layered structure formed in step S4. The outermost upper and lower surfaces are one surface of the exposed nonwoven fabric layer, that is, the first nonwoven fabric layer or the second nonwoven fabric layer not in contact with the polyolefin film. The coating liquid is applied to the outermost upper and lower surfaces of the coating liquid. The coating liquid is a solution in which inorganic particles are dispersed and a binder is dissolved in a solvent.

The inorganic particles and binders are as previously described herein. When only the polymer is used, the binder is dissolved in an appropriate solvent to prepare a coating solution. When a low molecular weight is contained as a binder, a polymer may be dissolved in a low molecular weight, and thus a solvent may not be used.

As the solvent, the solubility index is similar to the binder to be used, and it is preferable that the solvent has a low boiling point. This is because the mixing can be made uniform and then the solvent can be easily removed. Non-limiting examples of the solvent include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (N- methyl-2-pyrrolidone, NMP), cyclohexane, water or mixtures thereof.

The binder is dissolved in, for example, a solvent to prepare a binder solution. Mineral particles are added to the binder solution to form a slurry. At this time, a slurry in which the inorganic particles are dispersed in the binder solution is formed. The slurry is then applied to one side of the non-woven layer, for example, in a manner known in the art, and dried to form a porous coating layer. The formed porous coating layer is present on at least one of the one surface and the pores of the nonwoven fabric layer. This results in the formation of a three-layer structure on which the porous coating layer is formed.

 In step S6, the solvent is removed from the coated three-layer structure in step S5. This solvent removal can be carried out by extraction and drying. Through this removal, the space occupied by the solvent is left as pores to have a coating layer of porous structure.

According to these steps, a separation membrane for an electrochemical device having a three-layer structure is produced.

Claims (17)

A laminate in which a first nonwoven fabric layer, a porous polyolefin film and a second nonwoven fabric layer are laminated in this order, and
A porous coating layer in which inorganic particles and a binder are mixed on one surface of the first non-woven fabric layer not in contact with the porous polyolefin film, one surface of the second non-woven fabric layer,
Layer separator for an electrochemical device. The method according to claim 1,
Wherein the porous polyolefin film is a polymer membrane formed of one kind selected from the group consisting of polyethylene, polypropylene, polybutylene, and polypentene, or a combination of two or more thereof. The method according to claim 1,
Wherein the porous polyolefin film has a thickness of 1 to 20 占 퐉. The method according to claim 1,
Wherein the first nonwoven fabric layer and the second nonwoven fabric layer each independently comprise at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate for example, polycarbonate, polycarbonate, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyether But are not limited to, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylenesulfide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide polyethylene oxide, polyethylene-polyvinyl alcohol copolymer and polyethylene naphtha Wherein the polymer electrolyte membrane is a polymer membrane formed of one selected from the group consisting of polyethylenenaphthalene or a mixture of two or more thereof. The method according to claim 1,
Wherein the first nonwoven fabric layer and the second nonwoven fabric layer each independently have a thickness of 5 to 60 占 퐉. The method according to claim 1,
Wherein the first nonwoven fabric layer and the second nonwoven fabric layer are formed from composite fibers having a core-sheath structure independently of each other. The method according to claim 1,
Wherein the inorganic particles are selected from the group consisting of inorganic particles having a dielectric constant of 5 or more, inorganic particles having a lithium ion transporting ability, and mixtures thereof. The method according to claim 1,
Wherein the binder is selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), polyvinylidene fluoride-co-trichloroethylene, polyvinylidene fluoride- Polyvinylidene fluoride-co-chlorotrifluoroethylene, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate (also referred to as polyvinylpyrrolidone), polyvinylpyrrolidone polyvinyl acetate, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate ), Cyanoethylpullulan, cyano But are not limited to, polyvinyl alcohol, cyanoethylpolyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxyl methyl cellulose (CMC), acrylonitrile-styrene-butadiene But are not limited to, those selected from the group consisting of acrylonitrile-styrene-butadiene copolymer, polyimide, polyvinylidenefluoride, polyacrylonitrile, and styrene butadiene rubber (SBR) Or a mixture of two or more thereof. 9. An electrochemical device comprising an anode, a cathode, and a separator for an electrochemical device according to any one of claims 1 to 8 interposed between the anode and the cathode. 10. The method of claim 9,
Wherein the electrochemical device is a lithium secondary battery. Preparing a first nonwoven layer and a second nonwoven layer,
Preparing a porous polyolefin film,
A step of laminating the first nonwoven fabric layer, the porous polyolefin film and the second nonwoven fabric layer in order to form a laminate,
Rolling the laminate to form a three-layer structure,
Forming a porous coating layer on the outermost upper surface of the formed three-layered structure by coating a coating solution in which inorganic particles are dispersed and the binder is dissolved in a solvent, and
Removing the solvent from the coated three-layer structure to form a three-layered separator
Wherein the separator is formed of a metal. 12. The method of claim 11,
Wherein the step of forming the three-layer structure further comprises thermally fusing the layered product. 12. The method of claim 11,
The porous polyolefin film is a polymer film formed of one kind selected from the group consisting of polyethylene, polypropylene, polybutylene, polypentene, and the like, or a combination of two or more thereof, or a mixture of two or more thereof Wherein the separating film is formed on the substrate. 12. The method of claim 11,
Wherein the first nonwoven fabric layer and the second nonwoven fabric layer each independently comprise at least one selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate for example, polycarbonate, polycarbonate, polycarbonate, polyimide, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyether But are not limited to, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylenesulfide, polyvinyl alcohol, polyacrylic acid, polyethylene oxide polyethylene oxide, polyethylene-polyvinyl alcohol copolymer and polyethylene naphtha Wherein the polymer electrolyte membrane is a polymer membrane formed of one selected from the group consisting of polyethylenenaphthalene or a mixture of two or more thereof. 12. The method of claim 11,
Wherein the inorganic particles are selected from the group consisting of inorganic particles having a dielectric constant of 5 or more, inorganic particles having lithium ion transferring ability, and mixtures thereof. 12. The method of claim 11,
Wherein the binder is selected from the group consisting of polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichlorethylene, polymethylmethacrylate, poly Polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, polyvinylpyrrolidone, , Cellulose acetate butyrate, cellulose acetate propionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylcellulose, Cyanoethylsucros e), pullulan, carboxyl methyl cellulose, acrylonitrile-styrene-butadiene copolymer, polyimide, and butyl acrylate-ethyl acrylate -Cyanoacrylic copolymer, or a mixture of two or more of them. 12. The method of claim 11,
Wherein the solvent is selected from the group consisting of acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone, pyrrolidone, NMP), cyclohexane, water, or a mixture thereof.

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