Separator, method for manufacturing the same, and electrochemical element including the separator

Abstract

The present disclosure relates to a separator, a method of manufacturing the separator, and an electrochemical device including the separator. According to one embodiment of the present disclosure, there is provided a separator comprising: a porous substrate; and an inorganic particle layer that is formed on at least one surface of the porous substrate and contains inorganic particles and a binder containing a first water-soluble polymer including a metal carboxylate group and a second (meth) acrylamide-based water-soluble polymer. The diaphragm disclosed by the invention can effectively inhibit the decomposition reaction of the electrolyte to improve the performance of the electrochemical element.

Description

Technical Field

[0001] The present disclosure relates to a new separator that can effectively suppress the decomposition reaction of an electrolyte to improve the performance of an electrochemical element, a method for manufacturing the separator, and an electrochemical element comprising the separator. Background Art

[0002] Recently, as the demand for environmentally friendly technologies has increased dramatically, research on various energy sources has been intensively conducted. As such energy source, lithium secondary batteries are effectively used as power sources for mobile devices such as smartphones and notebook computers or electric vehicles due to their advantages of high energy density and low self-discharge.

[0003] Lithium secondary batteries use an electrolyte composed of a lithium salt and a non-aqueous solvent, which requires a high dielectric constant and high ion conductivity over a wide temperature range in order to dissolve the lithium salt.

[0004] In order to meet these requirements, cyclic carbonates represented by propylene carbonate, ethylene carbonate, etc., and linear carbonates represented by dimethyl carbonate, diethyl carbonate, etc. are mixed and used as a non-aqueous solvent.

[0005] However, although the electrolyte containing a lithium salt and a carbonate-based mixed solvent as described above shows excellent battery performance due to ionic conductivity, the electrolyte has the limitation of hydrolyzing by reacting with trace amounts of water present in the electrolyte. Moreover, HF, PO3F 2- The decomposition products not only act as catalysts for the decomposition reaction, but also affect the corrosion of the active material, thereby reducing the battery capacity and causing battery swelling due to the generation of gas.

[0006] The general solution for inhibiting electrolyte decomposition is to introduce electrolyte additives. However, these electrolyte additives are sensitive to moisture, so they are difficult to store and expensive, and can adversely affect the performance of the battery cell in the form of being dissolved in the electrolyte. As an example, U.S. Patent Gazette No. 2019-0386338 discloses a lithium secondary battery using a specific alkali metal salt as an electrolyte additive.

[0007] However, the electrolyte additives dissolved in the electrolyte as described above will inevitably have a negative impact on the performance of the battery cell, and therefore there is a need to study lithium secondary batteries that can more effectively inhibit the electrolyte decomposition reaction. Summary of the invention

[0008] Technical issues

[0009] An implementation example aims to provide a diaphragm capable of improving the performance of an electrochemical element by effectively suppressing the decomposition reaction of an electrolyte, a method for manufacturing the diaphragm, and an electrochemical element comprising the diaphragm.

[0010] In one implementation example, an object is to provide a separator having excellent heat resistance and adhesiveness while significantly suppressing the decomposition reaction of the electrolyte.

[0011] Specifically, the present disclosure aims to provide a novel separator and a method for manufacturing the same, wherein the separator is a separator having a porous substrate and an inorganic particle layer in which inorganic particles are interconnected to form pores between the inorganic particles, which inhibits decomposition of an electrolyte when assembled into a battery.

[0012] Furthermore, the purpose of the present disclosure is to provide a new diaphragm, a method for manufacturing the same, and an electrochemical element comprising the diaphragm. By designing an adhesive that connects and fixes inorganic particles to each other in the inorganic particle layer of the diaphragm when the battery is manufactured using the diaphragm, the decomposition reaction of the electrolyte inside the battery can be effectively suppressed through the action of the adhesive to improve the performance of the electrochemical element.

[0013] Technical Solution

[0014] The diaphragm according to the present disclosure includes: a porous substrate; and an inorganic particle layer, which is formed on at least one side of the porous substrate and contains an adhesive and inorganic particles, wherein the adhesive contains a first water-soluble polymer including a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

[0015] In a membrane according to an implementation example, the first water-soluble polymer is any one or more selected from the group consisting of polyacrylic acid metal salts, carboxymethyl cellulose metal salts and alginate metal salts, and the metal may include an alkali metal, an alkaline earth metal or a combination thereof.

[0016] In a membrane according to an implementation example, the weight average molecular weight of the first water-soluble polymer may be 2000 g / mol to 100000 g / mol.

[0017] In a separator according to an implementation example, the separator may include 1 to 20 parts by weight of the first water-soluble polymer based on 100 parts by weight of the inorganic particles.

[0018] In a separator according to an implementation example, the second water-soluble polymer may be poly(meth)acrylamide or a copolymer thereof.

[0019] In the separator according to an implementation example, the copolymer may be a copolymer including (meth)acrylamide-based monomer polymerization units, hydroxyl-containing (meth)acrylate-based monomer polymerization units, multifunctional (meth)acrylamide-based monomer polymerization units, or a combination thereof.

[0020] In a membrane according to an implementation example, the weight average molecular weight of the second water-soluble polymer may be 100,000 g / mol to 2,000,000 g / mol.

[0021] In a separator according to an implementation example, the separator may include 0.1 parts by weight to 10 parts by weight of the second water-soluble polymer based on 100 parts by weight of the inorganic particles.

[0022] In the separator according to an implementation example, the heat shrinkage rates of the separator in the MD direction and the TD direction measured after the separator is left at 150° C. for 60 minutes may be 2% or less.

[0023] The manufacturing method of the diaphragm according to the present disclosure includes: (S1) a step of preparing a slurry composition comprising a binder and inorganic particles; and (S2) a step of coating the slurry composition on at least one side of a porous substrate to form an inorganic particle layer, wherein the binder may comprise a first water-soluble polymer comprising a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

[0024] In a method for manufacturing a diaphragm according to an implementation example, the first water-soluble polymer is any one or more selected from the group consisting of polyacrylic acid metal salts, carboxymethyl cellulose metal salts and alginate metal salts, and the metal includes an alkali metal, an alkaline earth metal or a combination thereof.

[0025] In a method for manufacturing a diaphragm according to an implementation example, the weight average molecular weight of the first water-soluble polymer may be 2000 g / mol to 100000 g / mol.

[0026] In a method for manufacturing a diaphragm according to an implementation example, the second water-soluble polymer may be polyacrylamide or a copolymer thereof.

[0027] In a method for manufacturing a diaphragm according to an implementation example, the copolymer may be a copolymer including (meth)acrylamide monomer units, hydroxyl (meth)acrylate monomer units, multifunctional (meth)acrylamide monomer units, or a combination thereof.

[0028] The electrochemical element according to the present disclosure may include the separator as described above.

[0029] Effects of the Invention

[0030] According to an implementation example of the present disclosure, the separator includes a combination of specific water-soluble polymers, thereby effectively suppressing the decomposition reaction of the electrolyte to improve the performance of the electrochemical element, and simultaneously ensuring excellent heat resistance and adhesion.

[0031] An electrochemical element according to an implementation example includes the above-mentioned separator, thereby not only having the characteristic of reduced volume change of the electrochemical element, but also having significantly excellent life characteristics due to reduced resistance. DETAILED DESCRIPTION

[0032] The embodiments described in this specification can be modified into various other modes, and the technology according to one implementation example is not limited to the embodiments described below. Moreover, the implementation example is provided to more completely explain the present disclosure to ordinary technicians in the technical field.

[0033] Furthermore, singular forms used in the specification and the appended claims may be intended to include plural forms as well, unless the context clearly indicates otherwise.

[0034] Moreover, the numerical range used in this specification includes the lower limit, the upper limit, and all values ​​within the range, increments derived from the form and amplitude logic of the defined range, all values ​​of the double definition, and all possible combinations of the upper and lower limits of the numerical range defined in different forms. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may occur due to experimental errors or numerical rounding are also included in the defined numerical range.

[0035] Furthermore, throughout the specification, unless otherwise stated, “comprising” a certain constituent element does not mean excluding other constituent elements, but indicates that other constituent elements may also be included.

[0036] When it is described in this specification that a layer, film, region, plate or the like is “on” or “over” another part, this includes not only the case where it is “directly on” the other part, but also the case where there are other parts in between.

[0037] The terms "first", "second" and the like used in this specification can be used to describe various components, but the components should not be limited by these terms. The terms are only used to distinguish one component from other components.

[0038] The “monomer polymerization unit” used in the present specification may refer to a basic repeating unit of a polymer chain derived from the monomer.

[0039] In the present specification, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0040] In the expression "substituted or unsubstituted" in this specification, "substituted" means that one or more hydrogen atoms in the hydrocarbon are independently substituted by the same or different substituents. Non-limiting examples of the substituents include deuterium, halogen, hydroxyl, amino, C1 to C30 amine, nitro, C1 to C30 silyl, C1 to C30 alkyl, C1 to C30 alkylsilyl, C3 to C30 cycloalkyl, C1 to C30 heterocycloalkyl, C6 to C30 aryl, C1 to C30 heteroaryl, C1 to C20 alkoxy, C1 to C10 trifluoroalkyl or cyano.

[0041] In this specification, "Dn" (n is a real number) refers to the particle size of particles whose cumulative fraction on a volume basis is equivalent to n%. For example, "D50" refers to the particle size of particles whose cumulative fraction on a volume basis is equivalent to 50%. The Dn can be derived from the particle size distribution results of the inorganic particles to be measured, which are collected according to the KS A ISO 13320-1 standard and analyzed using a Multisizer4e Coulter counter (Coulter counter) of Beckman Coulter Company.

[0042] The existing method for inhibiting the decomposition of battery electrolytes is mainly to add additives as a component into the electrolyte, but such electrolyte additives have limitations such as being sensitive to moisture, difficult to store, expensive, and having an adverse effect on the performance of the battery cell in the form of being dissolved in the electrolyte.

[0043] In view of this, the present inventors have conducted intensive research and finally invented the present disclosure, that is, when a separator comprising a polymer having a metal carboxylate as a functional group and a (meth)acrylamide polymer as a binder is used in a battery, the above limitations can be overcome and electrolyte decomposition can be suppressed.

[0044] That is, the separator having an inorganic particle layer containing a binder according to the present disclosure can effectively suppress the decomposition reaction of the electrolyte through the design of the above-mentioned specific polymer combination, improve rather than reduce the performance of the electrochemical element, and ensure excellent heat resistance and adhesion. In addition, a battery having the characteristics of significantly reducing the changes in volume expansion of the electrochemical element over time can be provided, and the effect of having significantly excellent life characteristics due to the reduction of the resistance of the battery can be provided.

[0045] According to an implementation example, a separator includes: a porous substrate; and an inorganic particle layer, which is formed on at least one side of the porous substrate and includes a binder and inorganic particles, wherein the binder includes a first water-soluble polymer including a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer. In this case, the (meth)acrylamide-based polymer refers to a polymer including a (meth)acrylamide-based monomer polymerization unit.

[0046] The diaphragm comprises a mixed adhesive including the first water-soluble polymer and the second water-soluble polymer, thereby solving the problems caused by the electrolyte decomposition inhibitor added to the existing electrolyte, and significantly improving the performance of electrochemical elements such as lithium secondary batteries by effectively inhibiting the decomposition reaction of the electrolyte.

[0047] Specifically, a mixed adhesive comprising a first water-soluble polymer including a metal carboxylate group and a (meth) acrylamide-type second water-soluble polymer is used as the adhesive, so that the adhesive is stable to moisture, thereby providing an environmentally friendly aqueous diaphragm. According to an implementation example, the diaphragm includes an adhesive as described above, so that further side reactions can be suppressed by suppressing electrolyte decomposition inside the diaphragm. Moreover, the diaphragm has the advantages of excellent heat resistance and adhesion while significantly suppressing the decomposition reaction of the electrolyte. In terms of electrochemical elements using electrolyte decomposition inhibitors added to the electrolyte, there is a disadvantage that the electrolyte decomposition inhibitor dissolves in the electrolyte and has a negative impact on the performance of the battery cell. On the contrary, according to an implementation example, the electrochemical element is insoluble in the electrolyte because the adhesive contained in the diaphragm is insoluble in the electrolyte, so the existing problem that the electrolyte decomposition inhibitor dissolves in the electrolyte and has a negative impact on the performance of the battery cell can be solved. The electrochemical element can solve the existing problems as above and can suppress the decomposition of the electrolyte, so it can have excellent resistance characteristics and life characteristics.

[0048] Hereinafter, each component of the separator according to the implementation example of the present disclosure will be described.

[0049] As an implementation example, the first water-soluble polymer is a polymer including a metal carboxylate group. The first water-soluble polymer may be a homopolymer or a copolymer, and may include a metal carboxylate group in the main chain and / or the side chain.

[0050] The first water-soluble polymer is not particularly limited, and may be, for example, any one or more selected from the group consisting of polyacrylic acid metal salts, carboxymethyl cellulose metal salts, and alginate metal salts.

[0051] As an implementation example, the metal of the metal carboxylate group may include an alkali metal, an alkaline earth metal or a combination thereof, specifically sodium or lithium.

[0052] As an implementation example, the polyethylene glycol-converted weight average molecular weight of the first water-soluble polymer measured by gel permeation chromatography can be more than 2000g / mol, more than 3000g / mol, less than 100000g / mol, less than 50000g / mol, less than 40000g / mol, less than 30000g / mol, less than 15000g / mol or a value between the above numerical values. Specifically, the weight average molecular weight of the first water-soluble polymer can be 2000g / mol to 100000g / mol, 2000g / mol to 50000g / mol, 3000g / mol to 40000g / mol, 3000g / mol to 30000g / mol or 3000g / mol to 15000g / mol.

[0053] When the weight average molecular weight of the first water-soluble polymer of the separator according to an implementation example satisfies the above range, the decomposition suppression property, heat resistance and adhesiveness of the electrolyte can be further improved.

[0054] As an implementation example, the diaphragm may contain more than 1 part by weight, more than 2 parts by weight, more than 5 parts by weight, less than 20 parts by weight, less than 15 parts by weight, or a first water-soluble polymer with a value between the above values ​​relative to 100 parts by weight of inorganic particles. Specifically, the diaphragm may contain 1 to 20 parts by weight, 2 to 15 parts by weight, or 5 to 15 parts by weight of the first water-soluble polymer relative to 100 parts by weight of inorganic particles. When the content of the first water-soluble polymer of the diaphragm according to an implementation example satisfies the above range, the decomposition inhibition characteristics, heat resistance and adhesion of the electrolyte can be further improved.

[0055] In a preferred implementation example, the separator may contain 1 to 10 parts by weight, 1 to 9 parts by weight, or 2 to 8 parts by weight of the first water-soluble polymer relative to 100 parts by weight of the inorganic particles. When the content of the first water-soluble polymer meets the above range, it can be applied to a battery with better performance.

[0056] According to an implementation example, the diaphragm contains both the above-mentioned first water-soluble polymer and the (meth)acrylamide-type second water-soluble polymer, thereby effectively inhibiting the decomposition reaction of the electrolyte, improving the adhesion between the porous substrate and the inorganic particle layer, and improving the heat resistance at high temperatures.

[0057] The (meth)acrylamide-based second water-soluble polymer may be a homopolymer or a copolymer, and may be a homopolymer or a copolymer having (meth)acrylamide as a polymerization unit.

[0058] As an implementation example, the second water-soluble polymer may be poly(meth)acrylamide or a copolymer thereof. In an implementation example, the copolymer may be a block copolymer or a random copolymer, but the copolymer described in the present disclosure refers to a random copolymer obtained by mixing two or more monomers for polymerization.

[0059] As an implementation example, the copolymer including the poly(meth)acrylamide may be a copolymer including (meth)acrylamide monomer units, hydroxyl (meth)acrylate monomer units, multifunctional (meth)acrylamide monomer units or a combination thereof.

[0060] The copolymer including the poly(meth)acrylamide may include (meth)acrylamide-type monomer polymerization units, or may include (meth)acrylamide-type monomer polymerization units and hydroxyl-containing (meth)acrylate-type monomer polymerization units, or may include (meth)acrylamide-type monomer polymerization units and hydroxyl-containing (meth)acrylate-type monomer polymerization units and multifunctional (meth)acrylamide-type monomer polymerization units.

[0061] Preferably, when the second water-soluble polymer is a copolymer including (meth)acrylamide monomer polymerization units, hydroxyl (meth)acrylate monomer polymerization units and multifunctional (meth)acrylamide monomer polymerization units, the desired effect of the present disclosure can be well achieved, so it is preferred, but not limited to this. That is, according to an implementation example, the separator includes the copolymer, so the electrolyte decomposition inhibition characteristics, heat resistance and adhesion can be further improved.

[0062] In one implementation example, the (meth)acrylamide monomer polymerization unit may include a structure of the following Chemical Formula 1.

[0063] [Chemical formula 1]

[0064]

[0065] In the chemical formula 1, R1 to R3 may be independently hydrogen, or a substituted or unsubstituted linear or branched C1 to C6 alkyl group.

[0066] In one implementation example, the hydroxyl-containing (meth)acrylate monomer polymerization unit may include a structure of the following Chemical Formula 2.

[0067] [Chemical formula 2]

[0068]

[0069] In the chemical formula 2, R4 to R6 may be independently hydrogen or a C1 to C6 alkyl group, and L may be a C1 to C6 linear or branched alkylene group.

[0070] The polyfunctional (meth)acrylamide-based monomer polymerization unit may be generated by polymerizing a polyfunctional monomer represented by the following Chemical Formula 3.

[0071] [Chemical formula 3]

[0072]

[0073] In the chemical formula 3, R7 to R9 may be independently hydrogen, or a substituted or unsubstituted linear or branched C1 to C6 alkyl group, R 10 It may be a C1 to C10 straight chain or branched hydrocarbon group, and a may be 2 to 6, preferably, 2 or 3.

[0074] In the second water-soluble polymer according to an implementation example, 65 mol % to 98 mol % or 70 mol % to 95 mol % of (meth) acrylamide monomers may be included. Hydroxyl-containing (meth) acrylic monomers may be included from 2 mol % to 35 mol %, from 3 mol % to 30 mol % or from 5 mol % to 25 mol %. Multifunctional (meth) acrylamide monomers may be included from 0.001 mol % to 1 mol % or from 0.01 mol % to 0.5 mol %. In the case of preparing the second water-soluble polymer within the above content range, sufficient bonding strength can be obtained, more significant effects can be obtained in terms of high temperature shrinkage, and the decomposition reaction of the electrolyte can be effectively suppressed to further enhance the side reaction inhibition effect caused by the decomposition products of the electrolyte.

[0075] In an implementation example, the weight average molecular weight of the second water-soluble polymer can be more than 100000g / mol, more than 200000g / mol, less than 2000000g / mol, less than 1000000g / mol, less than 500000g / mol or a value between the above numerical values. Specifically, the weight average molecular weight of the second water-soluble polymer can be 100000g / mol to 2000000g / mol, 200000 to 1000000g / mol or 200000g / mol to 500000g / mol. According to an implementation example, when the weight average molecular weight of the second water-soluble polymer meets the above range, the decomposition inhibition characteristics, heat resistance and adhesion of the electrolyte can be further improved. The weight average molecular weight is the polyethylene glycol converted average molecular weight measured using gel permeation chromatography.

[0076] As long as a second water-soluble polymer according to the above implementation example can be provided, there is no particular limitation on the preparation method. However, in one implementation example, the second water-soluble polymer can be prepared by various known polymerization methods such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc.

[0077] In one implementation example, the second water-soluble polymer can be obtained by copolymerization of a mixture including the above-mentioned monomer components and a polymerization initiator.

[0078] In one implementation example, the type of the polymerization initiator is not particularly limited as long as the copolymer can be obtained, but in one implementation example, the polymerization initiator can be an azo initiator, a peroxide initiator, or a persulfate polymerization initiator such as potassium persulfate, sodium persulfate, or ammonium persulfate.

[0079] According to an implementation example, the second water-soluble polymer can be obtained by heating the temperature to 50° C. to 90° C. or 60° C. to 80° C. and then adding a polymerization initiator to cause a copolymerization reaction.

[0080] In one implementation example, after the copolymerization reaction is completed, the temperature may be lowered to room temperature (20±5° C.) and an alkaline solution or the like may be added to prepare a second water-soluble polymer aqueous solution adjusted to a neutral state.

[0081] In the diaphragm, in one implementation example, relative to 100 parts by weight of inorganic particles constituting the inorganic particle layer, the content of the second water-soluble polymer can be more than 0.1 parts by weight, more than 0.5 parts by weight, more than 1 part by weight, less than 10 parts by weight, less than 5 parts by weight, less than 3 parts by weight, or a value between the above values. Specifically, relative to 100 parts by weight of inorganic particles, 0.1 to 10 parts by weight, 0.5 to 5 parts by weight, or 1 to 3 parts by weight of the second water-soluble polymer may be included. According to an implementation example, when the content of the second water-soluble polymer of the diaphragm satisfies the above range, the decomposition inhibition characteristics, heat resistance and adhesion of the electrolyte can be further improved.

[0082] According to an implementation example, the separator has excellent heat resistance while effectively suppressing the decomposition reaction of the electrolyte. According to an implementation example, the longitudinal (MD) heat shrinkage and transverse (TD) heat shrinkage of the separator measured after being placed at 150°C for 60 minutes may be 2% or less or 1.5% or less, preferably, 1% or less, 0.8% or less, or 0.5% or less, and more preferably, 0.3% or less or 0.2% or less.

[0083] In one implementation example, the porous substrate can be a polyolefin porous substrate such as polyethylene, polypropylene, or copolymers thereof, but is not limited thereto, and all known porous substrates can be used as the porous substrate of the diaphragm of the electrochemical element. In one implementation example, the porous substrate can be manufactured into a film or a sheet, but is not particularly limited thereto.

[0084] In one implementation example, the thickness of the porous substrate may be 1 μm or more, 3 μm or more, 5 μm or more, 100 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, 15 μm or less, 12 μm or less, or a value between the above values, and may be 1 μm to 100 μm. In order to realize a high-capacity battery, it may be 3 μm to 50 μm, more specifically 5 μm to 20 μm, and more specifically 5 μm to 15 μm. Although not limited, the porous substrate may be made by stretching.

[0085] In an implementation example, the porosity of the porous substrate may be 20% to 60%, specifically 30% to 60%, but is not limited thereto.

[0086] In one implementation example, the Gurley transmittance of the porous substrate may be 50 sec / 100 cc or more, 70 sec / 100 cc or more, 1000 sec / 100 cc or less, 500 sec / 100 cc or less, 200 sec / 100 cc or less, 150 sec / 100 cc or less, or a value between the above values, and may be 50 sec / 100 cc to 500 sec / 100 cc, and may specifically be 70 sec / 100 cc to 200 sec / 100 cc, but is not limited thereto. The Gurley transmittance may be measured according to ASTM D726.

[0087] In one implementation example, the tensile strength in transverse direction (TD) and the tensile strength in machine direction (MD) of the porous substrate may be 1000 kgf / cm2, respectively. 2 Above, 1500kgf / cm 2 Above, 5000kgf / cm 2 Below, 4000kgf / cm 2 The values ​​below or between the above values ​​can be 1000 to 5000 kgf / cm 2 , specifically 1500kgf / cm 2 Up to 4000kgf / cm 2 , but is not limited to this.

[0088] In one implementation example, the porous substrate may be one that does not substantially include polar functional groups on the surface. According to an implementation example, the diaphragm includes a specific polymer combination as described above and a porous substrate that does not substantially include polar functional groups on the surface, so the decomposition inhibition characteristics of the electrolyte can be further improved. In this case, the so-called porous substrate does not substantially include polar functional groups can mean that the porous substrate contains less than 1 weight % or less than 0.5 weight % of polar functional groups based on the total weight of the porous substrate. Specifically, the porous substrate may be one that has not been subjected to a hydrophilic surface treatment and thus has not introduced polar functional groups. As non-limiting examples of the polar functional groups, carboxyl, aldehyde, hydroxyl, etc. can be listed, but are not particularly limited. According to one example, the hydrophilic surface treatment can be a corona discharge treatment or a plasma discharge treatment.

[0089] In one implementation example, the inorganic particle layer may include an adhesive and inorganic particles, and may be a porous inorganic particle layer in which inorganic particles are connected and fixed by the adhesive to form pores. In one implementation example, the inorganic particle layer is disposed on at least one side of the porous substrate, and the area fraction may account for more than 60%, more than 70%, more than 80% or more than 90% based on the entire surface of the porous substrate. Preferably, the inorganic particle layer may be formed on 100% of the area of ​​the porous substrate.

[0090] In one implementation example, the inorganic particle layer may be coated on one or both sides of the porous substrate. In the case where the inorganic particle layer is coated on both sides of the porous substrate, the thickness of the inorganic particle layer coated on one side and the other side may be the same or different. It is not particularly limited, but in one implementation example, the thickness of the inorganic particle layer coated on one side may be above 0.01 μm, above 0.2 μm, above 0.5 μm, below 15 μm, below 10 μm, below 5 μm, or a value between the above values. In a specific implementation example, the thickness of the inorganic particle layer may be 0.01 μm to 15 μm, 0.2 μm to 10 μm, or 0.5 μm to 5 μm. The thickness of the diaphragm was measured using a caliper thickness gauge. After stacking ten diaphragms, the thickness was measured at five different points of the ten diaphragms to obtain the average thickness of the ten diaphragms, and the value was divided by 10 to derive the average thickness of the diaphragm. The thickness of the inorganic particle layer was calculated by subtracting the thickness of the porous substrate from the thickness of the separator. The thickness of the porous substrate was calculated by stacking 10 porous substrates in the same manner as the thickness measurement of the separator.

[0091] As an implementation example, the inorganic particles are not limited as long as they are inorganic particles used in this technical field. As a non-limiting example, the inorganic particles may include one or more of metal hydroxides, metal oxides, metal nitrides and metal carbides, or may include silicon dioxide (SiO2), silicon carbide (SiC), magnesium oxide (MgO), yttrium oxide (Y2O3), aluminum oxide (Al2O3), cerium oxide (CeO2), calcium oxide (CaO), zinc oxide (ZnO), strontium titanate (SrTiO3), zirconium oxide (ZrO2), titanium dioxide (TiO2) and aluminum hydroxide (AlO (OH)) One or more. From the perspective of battery stability, preferably, the inorganic particles can be metal hydroxide particles such as boehmite.

[0092] The metal hydroxide is not particularly limited, but as a non-limiting example, it can include one or more of boehmite, aluminum hydroxide, and magnesium hydroxide. As an implementation example, when the boehmite is used, for example, the specific surface area (BET) can be 10 m 2 / g or above or 15m 2 / g and above, but not limited to.

[0093] In one implementation example, the average particle size (D50) of the inorganic particles can be greater than 0.01 μm, greater than 0.05 μm, greater than 0.1 μm, less than 5 μm, less than 3 μm, less than 2 μm, less than 1 μm, or a value between the above values, specifically 0.01 μm to 5 μm or 0.05 μm to 3 μm, more specifically 0.05 μm to 2 μm, and even more specifically 0.1 μm to 1 μm.

[0094] An implementation example provides a method for manufacturing a diaphragm, comprising: (S1) preparing a slurry composition comprising a binder and inorganic particles; and (S2) coating the slurry composition on at least one side of a porous substrate to form an inorganic particle layer, wherein the binder comprises a first water-soluble polymer comprising a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

[0095] Hereinafter, the steps of the method for manufacturing a separator according to the one implementation example will be described. The description of the porous substrate, inorganic particle layer, inorganic particles, first water-soluble polymer and second water-soluble polymer is the same as the above, so the detailed description will be omitted.

[0096] As a method for preparing the slurry composition in the step (S1), all conventional methods known in the technical field can be used without restriction. Although not particularly limited, according to a non-limiting example, the slurry can be prepared by stirring and dispersing inorganic particles, or a ball mill can be used to disperse agglomerated inorganic particles.

[0097] The slurry composition comprises inorganic particles, a first water-soluble polymer, a second water-soluble polymer and a solvent. The solvent may be water, ethanol, methanol, propanol and other lower alcohols, dimethylformamide, acetone, tetrahydrofuran, ether, methyl chloride, DMF, N-methyl-2-pyrrolidone, hexane, cyclohexane and other solvents or mixtures thereof, but is not necessarily limited thereto.

[0098] In one implementation example, the solid content of the slurry composition is not particularly limited, but for example, may be 1 wt % to 50 wt %, 5 wt % to 30 wt %, 10 wt % to 30 wt %, but is not limited thereto.

[0099] In one implementation example, the slurry composition may include 70 wt % to 95 wt % of inorganic particles, 1 wt % to 20 wt % of the first water-soluble polymer, and 0.1 wt % to 10 wt % of the second water-soluble polymer based on the total weight of the solid components. Specifically, it may include 80 wt % to 95 wt % of inorganic particles, 2 wt % to 15 wt % of the first water-soluble polymer, and 0.5 wt % to 5 wt % of the second water-soluble polymer, but is not limited to this.

[0100] As a method for applying the slurry composition in the step (S2), all conventional methods known in the art can be used without limitation, and according to non-limiting examples, roller coating, spin coating, dip coating, rod coating, pattern coating, slit coating, inkjet printing and a combination thereof can be used. The applied slurry can be dried to form an inorganic particle layer. The drying for forming the inorganic particle layer is not particularly limited, but can be dried at less than 100°C or 30°C to 60°C.

[0101] In a specific implementation example, after performing the drying for forming the inorganic particle layer, a process of aging the porous substrate formed with the inorganic particle layer may also be included. Specifically, the aging may be performed at 50°C to 150°C or 60°C to 120°C, and the aging time may be 2 hours to 24 hours or 10 hours to 20 hours. More specifically, it may be performed at a temperature range of 70°C to 120°C for 10 hours to 15 hours. The aging may improve the adhesion between the porous substrate and the inorganic particle layer, further improving the heat resistance at high temperatures.

[0102] According to one implementation example, an electrochemical device including the separator of one of the above implementation examples may be provided. The electrochemical device includes the separator as described above, so that the resistance is reduced and the device may have significantly excellent life characteristics.

[0103] The electrochemical element may be any known energy storage device and is not particularly limited, but as a non-limiting example, a lithium secondary battery may be cited. The lithium secondary battery is well known and its composition is also known, so it is not specifically described in this disclosure.

[0104] A lithium secondary battery according to an implementation example may be a battery including the above separator between a positive electrode and a negative electrode. In this case, as for the positive electrode and the negative electrode, any one commonly used for lithium secondary batteries may be used without limitation.

[0105] According to an implementation example, the separator is usually used in a battery by assembling a negative electrode, a separator and a positive electrode and injecting an electrolyte to complete the general manufacturing method, so it will not be described in detail here.

[0106] Hereinafter, embodiments and experimental examples are illustrated and described in detail below. However, the embodiments and experimental examples described below are only for illustration purposes, and the technology described in this specification is not limited thereto.

[0107] First, the method for evaluating the characteristics of the separator and the secondary battery will be described.

[0108] [Weight average molecular weight]

[0109] The weight average molecular weight was measured using GPC (Tosoh, EcoSEC HLC-8320GPC Reflective Index detector). The GPC columns used were Tskgel guard PWx, two TSKgel GMPWxl and TSKgel G2500PWxl (7.8×300 mm), the solvent was 0.1 M NaNO3 aqueous solution, the standard was polyethylene glycol, and the analysis was performed at 40°C with a flow rate of 1 mL / min.

[0110] [Electrolyte decomposition inhibition properties of separators]

[0111] In order to evaluate the electrolyte decomposition inhibition property of the separator, 0.8 g of the separator was immersed in 10 g of an electrolyte containing 1 M lithium hexafluorophosphate (LiPF6) dissolved in a solution of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and stored in an oven set at 60°C for 10 days. 19F NMR analysis was performed to analyze the electrolyte in which the separator was immersed to confirm the extent of the generation of electrolyte decomposition products represented by phosphine byproducts and HF. In detail, in order to quantify the electrolyte decomposition inhibition characteristics, the calculation 19 The HF content was determined by the integrated value of the HF peak in the F NMR analysis spectrum.

[0112] [Thermal shrinkage of diaphragm]

[0113] The thermal shrinkage of the diaphragm was determined based on ASTM D 1204, and was determined by the following method: a square with a side length of 10 cm on the diaphragm was marked with grid points at 2 cm intervals. One side of the square is transverse (TD, Transverse Direction) and the other side is longitudinal (MD, Machine Direction). Place the sample in the center, place five pieces of paper on the upper and lower parts of the sample, and wrap the four sides of the paper with tape. Place the paper-wrapped sample in a hot air drying oven at 150°C for 60 minutes. Then, take out the sample, observe the diaphragm with a camera, and calculate the longitudinal shrinkage of the following formula 1 and the transverse shrinkage of the following formula 2.

[0114] [Formula 1]

[0115] Longitudinal shrinkage (%) = {(longitudinal length before heating - longitudinal length after heating) / longitudinal length before heating} × 100

[0116] [Formula 2]

[0117] Transverse shrinkage (%) = {(transverse length before heating - transverse length after heating) / transverse length before heating} × 100

[0118] [Adhesion of diaphragm]

[0119] The diaphragm was cut into a size of 50 mm wide × 50 mm long, and the inorganic particle layer was arranged on the upper part. A black drawing paper (20 mm wide × 150 mm long × 0.25 mm thick) with a dynamic friction coefficient of 0.15 was placed on top of it, and a certain pressure (200 g / cm 2 ), then forcibly pull out the black drawing paper to the side to confirm the degree of inorganic matter attached to the surface, and refer to the following grades (Grade) to determine A / B / C / D / E / F according to the degree of attachment.

[0120] A: Not attached

[0121] B: A small amount of inorganic matter is attached

[0122] C to F are the levels at which both the adhesive and the inorganic substance are attached, and the closer to F, the more severe the degree.

[0123] [Initial performance of secondary battery]

[0124] In order to evaluate the initial performance of the secondary battery manufactured according to each example and comparative example, the resistance and discharge output of the secondary battery were measured according to the following methods, and the performance of the batteries of the remaining examples and comparative examples was relatively evaluated based on Comparative Example 1.

[0125] After the secondary battery was charged at 25° C. with 0.5 C CC / CV (4.2 V 0.05 C CUT-OFF), the battery thickness was measured.

[0126] The secondary battery was charged to 4.2 V, 0.05 C at a constant current-constant voltage (CC-CV) of 4.2 V at room temperature using a charge / discharge cycler, and then discharged to 2.7 V at a current of 0.5 C. The direct current internal resistance (DC-IR) was measured using a J-Pulse method at a state of charge (SOC) of 60%.

[0127] The output characteristics of the secondary battery at a state of charge (SOC) of 50% at room temperature were measured using the HPPC (Hybrid Pulse Power Characterization by FreedomCar Battery Test Manual) method.

[0128] [Life characteristics]

[0129] The secondary battery manufactured according to each embodiment and comparative example was charged and discharged at a constant current-constant voltage (CC-CV) of 4.2V using a charge / discharge cycler. The secondary battery was charged at a constant current of 0.5C rate at 25°C until the voltage reached 4.2V, and then charged at a constant voltage while maintaining 4.2V until the current reached 0.01C. After that, it was discharged at a constant current of 0.5C until the voltage reached 3.0V, and this cycle was repeated 800 times. For resistance, the direct current internal resistance (DC-IR) was measured using the J-Pulse method, and the resistance increase rate (△R) was calculated according to the following formula. The values ​​of the remaining embodiments and comparative examples were relatively evaluated based on Comparative Example 1. The lower the value, the lower the relative resistance increase rate.

[0130] △R(%)=(R2-R1) / R1×100

[0131] R1 is the initial resistance (mΩ) measured after the first cycle of each manufactured battery, and R2 is the resistance (mΩ) after 800 cycles.

[0132] In addition, the capacity retention rate (ΔC) was calculated according to the following formula. Similarly, the values ​​of the remaining examples and comparative examples were relatively evaluated based on Comparative Example 1. The higher the value, the higher the relative capacity retention rate.

[0133] △C(%)=(C2-C1) / C1×100

[0134] C1 is the initial discharge capacity (Ah) measured after the first cycle of each manufactured battery, and C2 is the discharge capacity (Ah) after 800 cycles.

[0135] [High temperature storage stability]

[0136] The secondary battery manufactured according to each embodiment and comparative example was stored in an oven at 60°C for 80 days, and then the direct current internal resistance (DC-IR) and discharge capacity were measured by the above-mentioned J-Pulse method. Then, the resistance increase rate (△R') and capacity retention rate (△C') were calculated according to the following formulas, and the values ​​of the remaining embodiments and comparative examples were relatively evaluated based on comparative example 1. In terms of resistance increase rate, the lower the value, the lower the relative resistance increase rate, and in terms of capacity retention rate, the higher the value, the higher the relative capacity retention rate.

[0137] △R'(%)=(R4-R3) / R3×100

[0138] R3 is the initial resistance (mΩ) of each manufactured battery before storage in an oven, and R4 is the resistance (mΩ) after storage in an oven at 60° C. for 80 days.

[0139] △C'(%)=(C4-C3) / C3×100

[0140] C3 is the discharge capacity (Ah) of each manufactured battery before storage in an oven, and C4 is the discharge capacity (Ah) after storage in an oven at 60° C. for 80 days.

[0141] <Preparation Example 1>

[0142] After the 1.0L flask was replaced with nitrogen, 1055mmol of acrylamide monomer components and 700g of distilled water were added to the flask and the temperature was raised to 75°C. After that, a polymerization reaction of a mixture in which 0.789mmol of ammonium persulfate was further added to the flask as a polymerization initiator was carried out in a sealed flask. After the polymerization reaction was carried out for 12 hours, the sealed flask was opened to the atmosphere and cooled to room temperature, and a 1M sodium hydroxide solution was added to adjust the pH to 7 to prepare a second water-soluble polymer aqueous solution. In this case, the weight average molecular weight of the prepared second water-soluble polymer was 280000g / mol.

[0143] <Preparation Example 2>

[0144] A second water-soluble polymer aqueous solution was prepared in the same manner as Preparation Example 1 except that 878 mmol of acrylamide and 2-hydroxyethyl methacrylate were used as monomer components. In this case, the weight average molecular weight of the prepared second water-soluble polymer was 300,000 g / mol.

[0145] <Preparation Example 3>

[0146] A second water-soluble polymer aqueous solution was prepared in the same manner as in Preparation Example 1 except that 932 mmol of acrylamide, 89 mmol of 2-hydroxyethyl methacrylate and 0.324 mmol of N,N'-methylenebisacrylamide were used as monomer components. In this case, the weight average molecular weight of the prepared second water-soluble polymer was 250,000 g / mol.

[0147] <Example 1>

[0148] Preparation of slurry composition

[0149] Based on the total weight of the solid content, boehmite (γ-AlO(OH) 90.35 wt%, boehmite) with an average particle size (D50) of 0.6 μm, 8.64 wt% of sodium polyacrylate (Sigma-aldrich, Mw: 5100 g / mol) and 1.01 wt% of the second water-soluble polymer prepared in Preparation Example 1 were added to water and stirred to prepare a slurry composition with a solid content concentration of 25 wt%.

[0150] Manufacturing diaphragms

[0151] A polyethylene porous film with a thickness of 9 μm (porosity: 48%, Gurley permeability: 82 sec / 100 cc, MD tensile strength: 2020 kgf / cm 2 , TD direction tensile strength: 1950kgf / cm 2) as a porous substrate. The slurry composition prepared above was applied to both sides of the porous substrate without surface treatment to form an inorganic particle layer with a thickness of 2.0 μm. The diaphragm was manufactured by aging the porous substrate with the inorganic particle layer at 80° C. for 12 hours. The properties of the diaphragm are included in the following Table 1.

[0152] Manufacturing secondary batteries

[0153] 94 wt% of LiCoO2 as a positive electrode active material, 2.5 wt% of polyvinylidene fluoride as a flux, and 3.5 wt% of carbon black as a conductive agent were added to N-methyl-2-pyrrolidone (NMP) as a solvent and stirred to prepare a uniform positive electrode slurry. The positive electrode slurry prepared above was coated on an aluminum foil with a thickness of 30 μm and dried and pressed to produce a positive electrode with a total thickness of 150 μm. 95 wt% of artificial graphite as a negative electrode active material, 3 wt% of acrylic latex with a Tg of -52°C as a flux, and 2 wt% of carboxymethylcellulose (CMC) as a thickener were added to water as a solvent and stirred to prepare a uniform negative electrode slurry. The negative electrode slurry prepared above was coated on a copper foil with a thickness of 20 μm and dried and pressed to produce a negative electrode with a total thickness of 150 μm. After assembling the pouch-type battery by stacking the positive electrode, negative electrode and separator manufactured above and arranging the separator between the positive electrode and the negative electrode, the assembled battery was heat-welded at 80°C and 1 MPa using a hot press to weld the positive electrode, negative electrode and separator to each other. After that, an electrolyte containing 1M lithium hexafluorophosphate (LiPF6) dissolved in a solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 30:50:20 was injected, and then sealed to produce a secondary battery with a capacity of 2Ah. The initial performance, life characteristics and high-temperature storage stability of the secondary battery are included in Table 2 below.

[0154] <Example 2>

[0155] A separator and a secondary battery were manufactured in the same manner as in Example 1, except that a slurry composition having a solid content concentration of 25% was prepared using 94.05% by weight of boehmite, 4.91% by weight of sodium polyacrylate, and 1.05% by weight of the second water-soluble polymer prepared in Preparation Example 1, based on the total weight of the solid content. The properties of the separator and the secondary battery are summarized in Tables 1 and 2 below.

[0156] <Example 3>

[0157] A separator and a secondary battery were manufactured in the same manner as in Example 2 except that the second water-soluble polymer prepared in Preparation Example 2 was used instead of the second water-soluble polymer prepared in Preparation Example 1. The properties of the separator and the secondary battery are shown in Tables 1 and 2 below.

[0158] <Example 4>

[0159] A separator and a secondary battery were manufactured in the same manner as in Example 2 except that the second water-soluble polymer prepared in Preparation Example 3 was used instead of the second water-soluble polymer prepared in Preparation Example 1. The properties of the separator and the secondary battery are shown in Tables 1 and 2 below.

[0160] <Comparative Example 1>

[0161] Preparation of slurry composition

[0162] Without using sodium polyacrylate, based on the total weight of the solid content, 97 wt% of boehmite (γ-AlO(OH)) with an average particle size (D50) of 0.6 μm and 3 wt% of the second water-soluble polymer prepared in Preparation Example 1 were added to water and stirred to prepare a slurry with a solid content concentration of 25 wt%.

[0163] Manufacturing diaphragms

[0164] A polyethylene porous film with a thickness of 9 μm (porosity: 48%, Gurley permeability: 82 sec / 100 cc, MD tensile strength: 2020 kgf / cm 2 , TD direction tensile strength: 1950kgf / cm 2 ) as a porous substrate. Both sides of the porous substrate were subjected to corona discharge treatment (power density 2W / mm) to introduce surface polar groups, in which case the speed of the corona discharge treatment was 3mp m to 20mpm (meter per minute). The slurry composition prepared above was applied to both sides of the porous substrate into which the surface polar groups were introduced to form an inorganic particle layer with a thickness of 2.0μm. The diaphragm was manufactured by aging the porous substrate formed with the inorganic particle layer at 80°C (agin g) for 12 hours. The properties of the diaphragm are included in the following Table 1.

[0165] Manufacturing secondary batteries

[0166] A secondary battery was manufactured in the same manner as in Example 1 except that the separator manufactured above was used. The characteristics of the secondary battery are shown in Table 2 below.

[0167] <Comparative Example 2>

[0168] A separator and a secondary battery were manufactured in the same manner as in Comparative Example 1 except that the second water-soluble polymer prepared in Preparation Example 3 was used instead of the second water-soluble polymer prepared in Preparation Example 1. The properties of the separator and the secondary battery are shown in Tables 1 and 2 below.

[0169] <Comparative Example 3>

[0170] A slurry, a separator and a secondary battery were prepared in the same manner as in Example 1 except that polyvinyl alcohol (Sigma-aldrich, Mw: 180000 g / mol) was used instead of the second water-soluble polymer of Preparation Example 1. The properties of the separator and the secondary battery are shown in Tables 1 and 2 below.

[0171] <Comparative Example 4>

[0172] A slurry, a separator and a secondary battery were prepared in the same manner as in Example 1 except that polyvinyl pyrrolidone (Sigma-aldrich, Mw: 55000 g / mol) was used instead of the second water-soluble polymer of Preparation Example 1. The properties of the separator and the secondary battery are shown in Tables 1 and 2 below.

[0173]

Table 1

[0174]

[0175]

Table 2

[0176]

[0177] Referring to Table 1 and Table 2, compared with Comparative Examples 1 to 4, the separators of Examples 1 to 4 can effectively inhibit the decomposition reaction of the electrolyte by including the first water-soluble polymer and the second water-soluble polymer according to an implementation example as a binder, and the longitudinal heat shrinkage and transverse heat shrinkage measured after being placed at 150°C for 60 minutes are 1.5% or less, which can confirm that the heat resistance is excellent, and the yellow paperboard adhesion is A, which can confirm that the adhesion can be significantly improved. In addition, it can be confirmed that the secondary batteries of Examples 1 to 4 are improved in initial performance, life characteristics and high temperature stability because they include the separator according to an implementation example.

[0178] Furthermore, it was confirmed that the batteries of Examples 2 to 4 had more excellent performance because they contained 1 to 9 parts by weight of the first water-soluble polymer based on 100 parts by weight of the inorganic particles.

[0179] Moreover, Examples 3 and 4 use a second water-soluble polymer prepared by including hydroxyl (meth)acrylate monomers and / or multifunctional (meth)acrylamide monomers other than (meth)acrylamide monomers as a binder, thereby exhibiting better electrolyte decomposition inhibition properties, heat resistance and adhesion, and the battery using the same also exhibits better initial performance, life characteristics and high temperature stability.

[0180] On the contrary, since Comparative Examples 1 and 2 do not use sodium polyacrylate as a binder, the heat resistance is lower than that of the embodiment, and an excessive amount of decomposition byproducts of the electrolyte are produced, and the amount of gas generated due to the decomposition of the electrolyte increases, so the initial performance, life characteristics and high-temperature stability of the battery are reduced.

[0181] It can be confirmed that Comparative Examples 3 and 4 use other types of polymers other than polyacrylamide polymers as binders, so the electrolyte decomposition inhibition characteristics, heat resistance, adhesion of the separator, and the initial performance, life characteristics and high-temperature stability of the secondary battery are inferior to those of the embodiments.

[0182] As described above, the present disclosure is described in this specification using specific matters and limiting embodiments, but this is only provided to help a more comprehensive understanding of the present disclosure. The present disclosure is not limited to the above embodiments, and a person of ordinary skill in the field to which the present disclosure belongs can make various modifications and variations from these records.

Claims

1. A diaphragm, comprising: Porous substrate; as well as an inorganic particle layer, which is formed on at least one side of the porous substrate and comprises a binder and inorganic particles, The adhesive comprises a first water-soluble polymer including a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

2. The diaphragm according to claim 1, wherein: The first water-soluble polymer is any one or more selected from the group consisting of polyacrylic acid metal salts, carboxymethyl cellulose metal salts and alginate metal salts. The metal includes an alkali metal, an alkaline earth metal or a combination thereof.

3. The diaphragm according to claim 1, wherein: The weight average molecular weight of the first water-soluble polymer is 2000 g / mol to 100000 g / mol.

4. The diaphragm according to claim 1, wherein: The first water-soluble polymer is contained in an amount of 1 to 20 parts by weight relative to 100 parts by weight of the inorganic particles.

5. The diaphragm according to claim 1, wherein: The second water-soluble polymer is poly(meth)acrylamide or a copolymer including poly(meth)acrylamide.

6. The diaphragm according to claim 5, wherein: The copolymer includes (meth)acrylamide monomer polymerization units, hydroxyl-containing (meth)acrylate monomer polymerization units, multifunctional (meth)acrylamide monomer polymerization units or a combination thereof.

7. The diaphragm according to claim 1, wherein: The weight average molecular weight of the second water-soluble polymer is 100,000 g / mol to 2,000,000 g / mol.

8. The diaphragm according to claim 1, wherein: The second water-soluble polymer is contained in an amount of 0.1 to 10 parts by weight relative to 100 parts by weight of the inorganic particles.

9. The diaphragm according to claim 1, wherein: The longitudinal heat shrinkage and transverse heat shrinkage of the separator measured after being left at 150° C. for 60 minutes were 2% or less.

10. A method for manufacturing a diaphragm, comprising: (S1) a step of preparing a slurry composition comprising a binder and inorganic particles; as well as (S2) a step of coating the slurry composition on at least one side of a porous substrate to form an inorganic particle layer, The adhesive comprises a first water-soluble polymer including a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

11. The method for manufacturing a diaphragm according to claim 10, wherein: The first water-soluble polymer is any one or more selected from the group consisting of polyacrylic acid metal salts, carboxymethyl cellulose metal salts and alginate metal salts. The metal includes an alkali metal, an alkaline earth metal or a combination thereof.

12. The method for manufacturing a diaphragm according to claim 10, wherein: The weight average molecular weight of the first water-soluble polymer is 2000 g / mol to 100000 g / mol.

13. The method for manufacturing a diaphragm according to claim 10, wherein: The second water-soluble polymer is polyacrylamide or a copolymer including polyacrylamide.

14. The method for manufacturing a diaphragm according to claim 13, wherein: The copolymer includes (meth)acrylamide monomer polymerization units, hydroxyl-containing (meth)acrylate monomer polymerization units, multifunctional (meth)acrylamide monomer polymerization units or a combination thereof.

15. An electrochemical element comprising the separator according to any one of claims 1 to 9.

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