KR101910222B1 - A multi-layered separator having high heat resistance property for a secondary battery - Google Patents

Abstract

The separator according to the present invention has a remarkably improved high heat resistance characteristic, and thus the battery using the separator has an effect of reducing heat shrinkage and shutdown even when used under high temperature conditions. The present invention provides a separation membrane for a secondary battery comprising two or more layers having different properties. According to a first aspect of the present invention, there is provided a separation membrane for a secondary battery according to the first aspect of the present invention, comprising: a base layer comprising a polyolefin resin; and a first inorganic layer and a second inorganic layer including polymer resin and inorganic particles on both sides of the base layer, Respectively.

Description

TECHNICAL FIELD [0001] The present invention relates to a multi-layered separator for a secondary battery,

The present invention relates to a separation membrane for a secondary battery. More specifically, the present invention relates to a separation membrane having two or more layers having different characteristics stacked thereon and having an improved function.

A secondary battery is a chemical battery that can be used semi-permanently by continuously repeating charging and discharging using an electrochemical reaction, and is 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 types of electrolytes, lithium ion secondary batteries using liquid electrolytes and solid electrolytes Lithium-ion polymer secondary battery.

The lithium secondary battery is composed of an anode, a cathode, an electrolyte, and a separator. Among them, separator is required to separate and electrically isolate an anode and a cathode, and has high permeability (permeability) of lithium ion based on high porosity. To increase the ionic conductivity. Polyolefin-based polymer films, such as polyethylene (PE) and polypropylene (PP), which are advantageous for forming pores and have excellent chemical resistance, mechanical properties and thermal properties, are widely used as polymer substrates of separators which are generally used. And is physically fragile. Efforts to overcome various problems of conventional polyolefin-based membranes have been actively conducted recently. For example, surface reforming of membranes for the purpose of improving affinity between electrolyte solutions and coextrusion, nonwoven fabric, and ceramic composite technologies Technology development is underway. Due to the nature of the fiber structure, the nonwoven fabric exhibits a large nonuniformity in pore structure and size compared with the commercialized polyolefin separator, which is deteriorated in battery performance. Especially, it exhibits insufficient performance such as current leakage at a momentary high current momentary discharge (10 seconds). Therefore, it is required to develop a new nonwoven fabric separator which overcomes such shortcomings in the field of nonwoven fabric separator.

It is an object of the present invention to provide a separation membrane having excellent safety and improved heat resistance. Other objects and advantages of the present invention will become apparent from the following description. It is also to be easily understood that the objects and advantages of the present invention can be realized by the means or method described in the claims, and the combination thereof.

The present invention provides a novel secondary battery separator for solving the above problems. The separation membrane includes a multi-layered layer structure, and includes a base layer comprising a polyolefin-based polymer resin; A first inorganic material layer formed on one side of the substrate layer and including a polyolefin-based polymer resin and first inorganic particles; And a second inorganic layer formed on the other side of the substrate layer and including a polymer resin and second inorganic particles.

Here, the polyolefin-based polymer resin of the base layer may be a high-density polyethylene, a polypropylene (propylene homopolymer), a polypropylene random copolymer, a poly-1-butene, Ethylene / 1-butene random copolymer, propylene / 1-butene random copolymer, or a mixture of two or more thereof.

Here, the first inorganic material layer contains the polyolefin-based polymer resin and the inorganic particles at a ratio of 10:90 to 90:10 in terms of weight ratio.

Here, the polyolefin-based polymer resin of the first inorganic material layer may be at least one selected from the group consisting of high density polyethylene, polypropylene (propylene homopolymer), polypropylene random copolymer, poly 1-butene, poly 4- Ethylene / 1-butene random copolymer, propylene / 1-butene random copolymer, or a mixture of two or more thereof.

Here, the polyolefin-based polymer resin of the first inorganic material layer is characterized in that a high-density polyethylene resin and a polypropylene resin are mixed.

Here, the first inorganic particles of the first inorganic material layer are electrochemically stable so that no oxidation and / or reduction reaction occurs at 0 V to 5 V, which is an operating voltage range of the lithium ion battery.

Here, the base layer and the first inorganic material layer are formed by co-extrusion.

Here, the second inorganic material layer is formed on the other side of the base material layer on which the first inorganic material layer is not formed by a coating method.

Here, the second inorganic material layer may be formed of a polyolefin-based polymer resin as the polymeric resin, and an electrochemically stable inorganic particle that does not cause oxidation and / or reduction reaction at 0 V to 5 V, which is the operating voltage range of the lithium ion battery, .

Here, the second inorganic particle is an inorganic particle having a dielectric constant of 5 or more or an inorganic particle having a lithium ion transferring ability.

Here, the fluorine-based polymer resin layer is further formed on one side of the first inorganic material layer that does not face the base material layer.

Here, the fluoropolymer resin layer has a thickness of 0.5 占 퐉 to 2 占 퐉.

The separator according to the present invention has greatly improved high heat resistance, and the heat shrinkage of the battery using the separator is reduced under high temperature conditions. In addition, since the separator base layer increases the occurrence of meltdown of the substrate layer during thermal runaway due to overheating in the battery, the shutdown can be induced early.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. On the other hand, the shape, size, scale or ratio of the elements in the drawings incorporated herein can be exaggerated to emphasize a clearer description.
Fig. 1 schematically shows the structure of a separation membrane according to the present invention comprising a base layer, a first inorganic layer and a second inorganic layer as one of the specific embodiments of the present invention.
2 schematically shows a structure of a separator according to the present invention comprising a substrate layer, a first inorganic material layer, a second inorganic material layer and a fluoropolymer resin layer as one of specific embodiments of the present invention.
3 is a process flow chart of the separation membrane for a secondary battery of the present invention.

The terms or words used in the present specification and claims should not be construed to be limited to ordinary or dictionary terms and the inventor shall properly define the concept of the term in order to best explain its invention The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a separation membrane for a secondary battery having a multilayer structure of two or more layers having different properties.

1 and 2 schematically show a separation membrane according to the first and second aspects of the present invention. Hereinafter, the present invention will be described in detail with reference to the drawings.

According to a first aspect of the present invention, there is provided a separation membrane for a secondary battery according to the first aspect of the present invention, comprising: a base layer comprising a polyolefin resin; and a first inorganic layer and a second inorganic layer including polymer resin and inorganic particles on both sides of the base layer, Respectively.

According to a second aspect of the present invention, the separation membrane for a secondary battery of the present invention further comprises a fluorine-based polymer resin layer on the first inorganic material layer.

According to a first aspect of the present invention, there is provided a separation membrane for a secondary battery according to the present invention, wherein a first inorganic material layer comprising a polyolefin-based polymer resin and first inorganic particles is formed on one side of the base material layer by co- And a second inorganic material layer containing a polyolefin-based polymeric binder resin and a second inorganic material on the other side of the substrate layer.

1. Base layer

According to a specific embodiment of the present invention, the substrate layer comprises a polyolefin-based polymer resin. The polyolefin-based polymer resin is excellent in mechanical properties and chemical stability, and exhibits properties suitable for a secondary battery separator. The polyolefin-based polymer resin may be at least one selected from the group consisting of high density polyethylene, polypropylene (propylene homopolymer), polypropylene random copolymer, poly 1-butene, poly 4-methyl-1-pentene, Butadiene random copolymer, and a propylene / 1-butene random copolymer. However, the present invention is not limited thereto. These olefin-based polymer resins may be used singly or in combination of two or more. Preferably, the base layer contains polyethylene in an amount of 80 parts by weight or more, or 90 parts by weight or more, based on 100 parts by weight of the total polymer resin.

According to a specific embodiment of the present invention, the base layer and the first inorganic material layer are simultaneously formed by a co-extrusion method as described later. Like the conventional dry separation membrane manufacturing process, the substrate layer is microcracked at the lamellar crystal interface as the extruded film is stretched at a high temperature.

The base layer has porosity of 30% to 60%, preferably 35% to 55%, more preferably 40% to 50% in consideration of stable ion conductivity required in the secondary battery separator. The pores formed in the base layer have a diameter of 10 nm to 100 nm, preferably 20 nm to 80 nm, more preferably 30 nm to 60 nm. In the present invention, it is preferable that the thickness of the cross-section of the base layer laminated with the final film is at least 5 탆 or more considering the mechanical strength.

2. First inorganic layer

The first inorganic layer is provided to improve the mechanical strength and heat resistance of the separator according to the present invention. Especially to prevent thermal shrinkage of the substrate layer under high temperature conditions to enhance the morphological stability of the separator.

The first inorganic material layer includes a polyolefin-based polymer resin and inorganic particles. The polyolefin-based polymer resin of the first inorganic material layer may be at least one selected from the group consisting of high density polyethylene, polypropylene (propylene homopolymer), polypropylene random copolymer, poly 1-butene, poly 4-methyl- Butadiene random copolymer, a 1-butene random copolymer, and a propylene / 1-butene random copolymer, but the present invention is not limited thereto. These olefin-based polymer resins may be used singly or in combination of two or more kinds, and high-density polyethylene, polypropylene or a mixture thereof may be used.

In one embodiment of the present invention, the polymer resin contained in the first inorganic material layer has a polypropylene content of 30 parts by weight or more, preferably 30 parts by weight to 55 parts by weight, based on 100 parts by weight of the total polymer resin.

The first inorganic material layer is a mixture of the first inorganic material particles with the polyolefin polymer resin. The inorganic particles 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 + of a lithium ion battery). Particularly, 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 be increased, and the ion conductivity of the electrolyte can be improved. Although the kind of the inorganic particles is not particularly limited, inorganic particles selected from the group consisting of inorganic particles having a dielectric constant of about 5 or more, inorganic particles having a lithium ion transferring ability (in the case of a lithium secondary battery), and mixtures thereof may be used . The inorganic particles having a dielectric constant of about 5 or more include BaTiO ₃ , Pb (Zr _x , Ti _1-x ) O ₃ (PZT, 0 <x <1), Pb _{1 -x} La _x Zr _{1 -y} Ti _y O ₃ (PMN-PT, 0 < x < 1), and half (PZT, 0 <x <1, 0 <y <1), (1-x) Pb (Mg _1/3 Nb _2/3 ) O ₃ -xPbTiO ₃ It is preferable to use HfO ₂ , SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, NiO, CaO, ZnO, ZrO ₂ , SiO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , SiC and TiO ₂ , But is not limited thereto. As the inorganic particles having lithium ion transferring ability, 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), (LiAlTiP) _x O _y series glass 0 <y <13), lithium lanthanum titanate (Li _x La _y TiO _3, 0 <x <2, 0 <y <3), lithium germanium thiophosphate (Li _x Ge _y P _z S _w , x <4, 0 <y < 1, 0 <z <1, 0 <w <5), lithium nitrides _{(Li x N y, 0 <} x <4, 0 <y <2), SiS 2 (Li x _{Si y S z, 0 <x} <3, 0 <y <2, 0 <z <4) based glass, and _{P 2 S 5 (Li x P} y S z, 0 <x <3, 0 <y <3, 0 < z < 7) series glass or the like is preferably used, but is not limited thereto.

The first inorganic particle has an average particle size of from about 100 nm to about 1,000 nm, or from about 200 nm to about 800 nm, or from about 200 nm to about 600 nm. If the particle diameter of the inorganic particles is excessively fine to less than 100 nm, the polymer particles may not be uniformly dispersed in the polymer resin, and the resistance characteristics of the separation membrane may be deteriorated. On the other hand, the content of the inorganic particles in the first inorganic material layer is 10 to 90 parts by weight, 30 to 70 parts by weight, or 50 to 70 parts by weight based on 100 parts by weight of the polyolefin polymer resin.

If the inorganic particles are included in the first inorganic layer in the above-described range, the thermal and mechanical strength of the separator can be improved due to the inorganic particles incorporated therein. In the first inorganic material layer, the interface between the inorganic particles and the polymer resin is separated by the stretching process to be described later, and micropores are generated therebetween to form a porous . Accordingly, the first inorganic material layer is advantageous in forming a separator having excellent ionic conductivity and electrolyte impregnability. On the other hand, when the content of the inorganic particles exceeds the above range and is mixed in an excessively large amount, the content of the polymer resin serving as a binder of the particles is insufficient and the particles may be desorbed during the stretching and drying process of the film.

According to an embodiment of the present invention, the surface of the first inorganic particle may be modified with an organic material, and the organic material may include, but not limited to, a carboxylic acid having 6 to 18 carbon atoms, a ketone, Or a mixture of two or more.

According to a specific embodiment of the present invention, the first inorganic material layer is formed by a co-extrusion method together with the base material layer described above. Extruding the sheet in the form of a sheet in which a base layer and a first inorganic material layer are sequentially laminated by the co-extrusion, and stretching the film in a sheet form at a high temperature of 100 DEG C or higher to form the first inorganic particles and the polymeric resin The fine pores are formed in the first inorganic material layer as the microcracks are generated at the interface of the first inorganic material layer. The porosity of the first inorganic material layer is 20% to 80%, preferably 30% to 60%, more preferably 35% to 55%. The final thickness of the first inorganic material layer should be 3 탆 or more. The pores formed in the base layer have a diameter of 10 nm to 100 nm, preferably 20 nm to 80 nm, more preferably 30 nm to 60 nm.

The method of forming the base layer and the first inorganic material layer may be a conventional co-extrusion method used in the industry for producing a thin film. A method of forming the base layer and the first inorganic material layer by co-extrusion will be described below in detail (S100). First, the polymer resin to be used for the base layer (S110) and the polymer resin to be used for the first inorganic material layer are supplied to separate hoppers, respectively, and melted by an extruder. At this time, the inorganic particles are injected into the polymer resin to be used for the first inorganic material layer within the above-mentioned content range. (S120) Each of the molten polymer resins is extruded through a T die for co-extrusion. Thereby, an unstretched film in which the base layer and the first inorganic material layer are laminated is obtained. Here, the extrusion temperature is not particularly limited and can be appropriately adjusted according to the polymer resin used. (S130) Next, the co-extruded film is cooled using a cooling roll. (S140), the cooled film is preheated and then stretched in the machine direction and / or width direction. The uniaxial and / or biaxial elongation is 3 to 7 times in the machine direction and / or width direction. A stretched film in which the base layer and the first inorganic material layer are laminated can be obtained by the above-described method. As described above, in the substrate layer, microcracks are generated in the lamellar crystal interface of the film by stretching to multiply the first inorganic material layer, and the first inorganic material layer is polished according to the microcracks generated at the interface between the first inorganic particles and the polymer resin .

3. Second inorganic layer

The separation membrane according to the present invention further comprises a second inorganic material layer. The second inorganic material layer is formed on the other side of the base material layer where the first inorganic material layer is not laminated. The second inorganic material layer includes a polymer resin and a second inorganic material particle. The second inorganic layer is provided to improve the mechanical strength and heat resistance of the substrate layer according to the present invention. And is intended to prevent heat shrinkage of the substrate layer under high temperature conditions, thereby enhancing the morphological stability of the separator.

The second inorganic material layer comprises a polyolefin-based polymer resin as a polymer resin. Here, the polyolefin polymer resin may be the same as the polyolefin polymer resin used for the first inorganic material layer. Thus, the substrate for the polyolefin polymer resin of the second inorganic layer is replaced with the substrate for the first inorganic layer and referenced therein. The second inorganic particle of the second inorganic material layer according to the second aspect of the present invention may be oxidized and / or reduced at an operating voltage range of the applied electrochemical device (e.g., about 0 to about 5 V based on Li / Li +) It is not particularly limited. A detailed description of the second inorganic particles may be the same as the first inorganic particles of the first inorganic layer. Thus, the description of the second inorganic particle is replaced by the description of the first inorganic particle and refers to it. In the second inorganic material layer according to the second aspect of the present invention, the composition ratio of the polyolefin polymer resin and the second inorganic particles may be controlled within a range of 1:99 to 90:10 by weight, particularly 50:50 to 1:99 Range is preferred. If the weight ratio of the inorganic particles is less than 90:10, the amount of the polymer is excessively increased, resulting in a decrease in the pore size and porosity due to the reduction of the space formed between the inorganic particles, The mechanical properties of the second inorganic material layer are deteriorated due to the weakening of the adhesion between the inorganic materials because the polymer content is too small.

That is, as the ratio of the inorganic particles (I) to the polymer (P) increases, the porosity of the second inorganic material layer of the present invention increases as the ratio of the inorganic particles (I) ), Resulting in an increase in the thickness of the organic / inorganic composite porous membrane. Also, the pore size increases due to an increase in the possibility of forming pores between the inorganic particles. At this time, as the size (particle size) of the inorganic particles increases, the interstitial distance between the inorganic particles increases.

The second inorganic material layer has a porous structure formed by an interstitial interstitial volume between the inorganic particles. In the present invention, an interstitial volume is a space defined by inorganic particles substantially interfaced with a densely packed sturucture. The impregnation rate of the electrolyte can be improved by the porous structure of the second inorganic material layer. The second inorganic material layer can form the pore structure of the second inorganic material layer together with the pores included in the substrate layer by controlling the size of the inorganic particles and the composition of the inorganic particles and the polymer resin, .

The second inorganic material layer has a pore size of 10 mu m to 100 mu m, preferably 30 mu m to 70 mu m, more preferably 50 mu m to 60 mu m. Since the pores of the second inorganic material layer are formed by the spaces formed between the particles, the pores of the second inorganic material layer may be relatively large compared to the pores formed by the stretching of the film in the base material layer or the first inorganic material layer.

Next, a method of laminating the second inorganic material layer on the substrate layer of the stretched film obtained above will be described. In one embodiment of the manufacturing method according to the present invention, a composition for forming a second inorganic layer is prepared by mixing inorganic particles and a polymer resin (S200). The composition may be prepared, for example, by preparing a polymer resin solution by dissolving a polymer resin in a solvent, adding and mixing second inorganic particles to the polymer resin solution to prepare a composition for forming a second inorganic layer. Next, the composition is coated on the surface of the base layer and dried to coat the second inorganic layer (S300). The coating may be carried out by a conventional coating method, such as a dip coating, a die coating, a roll coating, a comma coating, or a combination thereof.

In the above, it is preferable to carry out the crushing of the inorganic particles after adding the second inorganic particles to the polymer resin solution. In this case, the disintegration time is preferably 1 to 20 hours, and the particle size of the disintegrated inorganic particles is as described above. As the crushing method, a conventional method can be used, and a ball mill method is particularly preferable.

The solvent preferably has a similar solubility index to the polymer to be used and 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, methylenechloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (N- methyl-2-pyrrolidone (NMP), cyclohexane, water or a mixture thereof.

4. Fluorine-based polymer resin layer

According to a second aspect of the present invention, the separation membrane of the present invention further comprises a fluoropolymer resin layer on the surface of the first inorganic material layer and / or the surface of the second inorganic material layer.

The fluoropolymer resin may be at least one selected from the group consisting of PVdF, PVdF-TEF (tetrafluoroethylene), PVdF-HFP (hexafluoropropylene), PVdF-PFA (perfluoro alkoxy ethylene), PVdF-ETEF (ethylene tetrafluoroethylene), PVdF- (chlorotrifluoroethylene) and PVdF-ECTFE (ethylene chlorotrifluoroethylene). However, the present invention is not limited thereto. The fluorine-based polymer resin layer improves the adhesion to the electrodes in the lamination process of the electrode and the separator. Since the melting point of the fluorine-based polymer resin layer is higher than that of the polyethylene base layer, the meltdown of the base layer is maintained at a certain temperature level, There is an effect that can be prevented. In the present invention, the fluorine-based resin layer does not have pores and the electrolyte moves along a movement mechanism composed of absorption-diffusion-desorption in a noncrystalline region. The fluoropolymer resin layer has a thickness of 0.5 탆 to 2 탆, preferably 0.5 탆 to 1 탆. If the thickness does not fall within the above-mentioned range, a predetermined adhesive force can not be exerted at the time of adhering to the electrode. On the other hand, if it exceeds the above-mentioned range, absorption and diffusion of the electrolyte can be prevented.

According to a preferred embodiment of the present invention, the fluorine-based polymer resin layer is formed on the first inorganic material layer (S400). The method of forming the fluorine-based polymer resin layer is not particularly limited, and a conventional coating method can be applied. Examples of the coating method include a dip coating, a die coating, a roll coating, a comma coating, or a mixing method thereof, but the present invention is not limited thereto. For example, the fluoropolymer resin layer may be formed by melting the fluoropolymer resin or by dissolving the fluoropolymer resin in a suitable solvent, and then applying and drying the fluoropolymer resin on the first inorganic material layer.

According to another aspect of the present invention, an electrochemical device including the positive electrode, the negative electrode, and the above-described separator interposed between the positive electrode and the negative electrode may be manufactured. The electrochemical device of the present invention includes all devices that perform an electrochemical reaction. Examples of the electrochemical device include capacitors such as all types of primary cells, secondary cells, fuel cells, solar cells, and super capacitors. Particularly, 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 is preferable among the above secondary batteries.

The anode, the cathode and the like can be easily produced by a process and / or a method known in the art.

The anode is prepared by binding a cathode active material to a cathode current collector according to a conventional method known in the art. As the cathode active material, a conventional cathode active material that can be used for a cathode of a conventional electrochemical device can be used. Examples of the cathode active material include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , Li (Ni _a Co _b Mn _c ) O ₂ (0 <a <1, 0 <b <1, a + b + c = 1), LiNi _{1 -Y} Co _Y O ₂ , LiCo _{1 -Y} Mn _{Y 2} O, LiNi _{1 -Y} Mn _Y O ₂ (where, 0≤Y <1), Li ( Ni a Co b Mn c) O 4 (0 <a <2, 0 <b <2, a + b + c = 2), LiMn 2-Z Ni _Z O _4, LiMn include _2-Z Co _Z O ₄ (where, 0 <Z <2), LiCoPO 4, LiFePO 4 , and mixtures thereof. The anode current collector may be made of aluminum, nickel, or a combination thereof.

The negative electrode is prepared by adhering the negative electrode active material to the negative electrode current collector according to a conventional method known in the art. At this time, the negative electrode active material may be carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides of Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, Bi ₂ O ₅ and the like; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like can be used. On the other hand, as the negative electrode current collector, stainless steel, nickel, copper, titanium or an alloy thereof can be used.

Also, the electrolyte that can be inserted between the electrode and the separator is a salt having a structure such as A ⁺ B ^- , where A ⁺ includes an alkali metal cation such as Li ⁺ , Na ⁺ , K ⁺ and B ^- is _{^{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 - (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and the like, and salts containing anions such as C (CF ₂ SO ₂ ) ₃ ^- But are not limited to, dipropyl carbonate (DPC), dimethylsulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (? -butyrolactone), or a mixture thereof, but is not limited thereto All.

The electrolyte may be injected at an appropriate stage of the battery manufacturing process, depending on the manufacturing process and required properties of the final product.

As a process for applying the separator 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 general process of winding.

100 membrane
110 base layer
120 first inorganic layer
130 second inorganic layer
140 Fluoropolymer resin layer

Claims (16)

A base layer comprising a polyolefin-based polymer resin;
A base material layer formed on one side of the substrate layer, wherein the polyolefin-based polymer resin and the first inorganic material
A first inorganic layer comprising particles; And
And a second inorganic particle formed on the other side of the base layer and including a polymer resin and a second inorganic particle
A second inorganic layer,
Wherein the substrate layer and the first inorganic material layer are formed by coextrusion, and the second inorganic material layer is formed by a coating method on the other side of the base material layer on which the first inorganic material layer is not formed,
A fluorinated polymer resin layer is further formed on one side of the first inorganic material layer that does not face the base material layer,
The pores of the second inorganic material layer are formed by a space formed between the particles, and the pores of the first inorganic material layer are formed by stretching the film. The pores of the second inorganic material layer are larger than the pores of the first inorganic material layer Wherein the separator is a separator for a secondary battery.
The method according to claim 1,
The polyolefin-based polymer resin of the base layer may be at least one selected from the group consisting of high density polyethylene, polypropylene (propylene homopolymer), polypropylene random copolymer, poly 1-butene, poly 4-methyl- -Butene random copolymer, and propylene / 1-butene random copolymer, or a mixture of two or more thereof.
The method according to claim 1,
Wherein the first inorganic material layer comprises a polyolefin-based polymer resin and inorganic particles in a weight ratio of 10:90 to 90:10.
The method of claim 3,
The polyolefin-based polymer resin of the first inorganic material layer may be at least one selected from the group consisting of high density polyethylene, polypropylene (propylene homopolymer), polypropylene random copolymer, poly 1-butene, poly 4-methyl- A 1-butene random copolymer, a propylene / 1-butene random copolymer, or a mixture of two or more thereof.
The method of claim 3,
Wherein the polyolefin-based polymer resin of the first inorganic material layer is a mixture of a high-density polyethylene resin and a polypropylene resin.
The method of claim 3,
Wherein the first inorganic particles of the first inorganic material layer is electrochemically stable so that oxidation and / or reduction reaction does not occur at an operating voltage range of 0 V to 5 V, which is an operating voltage range of the lithium ion battery.
delete delete The method according to claim 1,
Wherein the second inorganic material layer comprises a polyolefin-based polymer resin as the polymer resin, and electrochemically stable inorganic particles that do not undergo oxidation and / or reduction reaction at 0 V to 5 V in the operating voltage range of the lithium ion battery as the second inorganic particles A separator for a secondary battery.
10. The method of claim 9,
Wherein the second inorganic particles are inorganic particles having a dielectric constant of 5 or more or inorganic particles having a lithium ion transporting ability.
delete The method according to claim 1,
Wherein the fluorine-based polymer resin layer has a thickness of 0.5 탆 to 2 탆.
And a separator interposed between the cathode and the anode, wherein the separator comprises the cathode, the anode, and the separator interposed between the cathode and the anode, wherein the separator comprises the separator according to any one of claims 1, 2, 3, 4, 5, 6, 9, And the separator according to any one of claims 1 to 12. In the separation membrane production method,
(S100) forming a porous stretched film in which a base layer and a first inorganic material layer are laminated by coextrusion;
(S200) mixing the inorganic particles and the polymer resin to prepare a composition for forming a second inorganic layer; And
(S300) coating the composition prepared in (S200) on the substrate layer of the porous stretched film to form a second inorganic material layer; And the separator is the separator according to any one of claims 1 to 6. A method for producing a separator for a secondary battery,
15. The method of claim 14, wherein the step (S100)
(S110) melting the polymeric resin (A) for a substrate layer to be used for the substrate layer and the polymeric resin (B) for a first inorganic layer to be used for the first inorganic layer in separate hoppers;
(S120) co-extruding the molten polymer resin (A) and (B) to obtain an unstretched film in which a base layer and a first inorganic material layer are laminated;
(S130) cooling the unstretched film; And
(S140); and stretching the cooled unoriented film.
15. The method of claim 14,
(S400) further comprises forming a fluoropolymer resin layer on a surface of the first inorganic material layer, the second inorganic material layer, or both of the first inorganic material layer and the second inorganic material layer.

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