Separator, manufacturing method thereof, and electrochemical device including separator

Abstract

To provide a separator, a manufacturing method thereof, and an electrochemical device including the separator.SOLUTION: A separator according to an embodiment of the present disclosure includes a porous substrate and an inorganic particle layer formed on at least one surface of the porous substrate and further includes a binder and inorganic particles, and the binder includes a first water-soluble polymer having a metal carboxylate group and a second water-soluble (meth)acrylamide-based polymer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a new separator capable of effectively suppressing the decomposition reaction of an electrolyte to improve the performance of an electrochemical device, a method for manufacturing the same, and an electrochemical device including the separator.

Background Art

[0002] Recently, with the rapid increase in demand for environmentally friendly technologies, research on various energy sources has been intensively conducted. As such an energy source, a lithium secondary battery is usefully used as a power source for mobile devices such as smartphones and notebook computers or electric vehicles due to its advantages of high energy density and low self-discharge.

[0003] A lithium secondary battery uses an electrolyte composed of a lithium salt and a non-aqueous solvent. The non-aqueous solvent is required to have a high dielectric constant and high ionic conductivity in a wide temperature range in order to dissolve the lithium salt.

[0004] To meet such needs, 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 an electrolyte containing a lithium salt and a carbonate-based mixed solvent exhibits excellent battery performance depending on the ionic conductivity, the electrolyte has a limit in reacting with trace amounts of moisture present in the electrolyte and hydrolyzing. In addition, decomposition products such as HF and PO 3 F 2- not only act as a catalyst for the decomposition reaction but also affect the corrosion of the active material, causing a decrease in the capacity of the battery and swelling of the battery due to gas generation.

[0006] A common method for suppressing the decomposition of electrolytes is to introduce electrolyte additives. However, such electrolyte additives are sensitive to moisture, difficult to store, expensive, in a form dissolved in the electrolyte, and can have an adverse effect on the performance of the cell. As an example, U.S. Patent Publication No. 2019-0386338 discloses a lithium secondary battery using a specific alkali metal salt as an electrolyte additive.

[0007] However, since electrolyte additives in a form dissolved in the electrolyte inevitably have a negative impact on the performance of the cell, there is a need for research on lithium secondary batteries that can more effectively suppress the electrolyte decomposition reaction.

Summary of the Invention

Problems to be Solved by the Invention

[0008] One embodiment provides a separator, a method for manufacturing the same, and an electrochemical device including the separator, which can improve the performance of the electrochemical device by effectively suppressing the decomposition reaction of the electrolyte.

[0009] Also, in one embodiment, a separator is provided that significantly suppresses the decomposition reaction of the electrolyte and has excellent heat resistance and adhesiveness.

[0010] Specifically, the present disclosure provides a separator having a porous substrate and an inorganic particle layer in which the inorganic particles are connected to each other to form pores between the inorganic particles, and a new separator and a method for manufacturing the same that suppress the decomposition of the electrolyte when assembled into a battery.

[0011] Further, when manufacturing a battery using the separator, by designing a binder that connects and fixes the inorganic particles to each other in the inorganic particle layer of the separator, the decomposition reaction of the electrolyte inside the battery can be effectively suppressed by the action of the binder, and a new separator, a method for manufacturing the same, and an electrochemical device including the separator that can improve the performance of the electrochemical device are provided.

Means for Solving the Problem

[0012] The separator according to the present disclosure includes a porous substrate and an inorganic particle layer formed on at least one surface of the porous substrate and containing a binder and inorganic particles, and the binder includes a first water-soluble polymer containing a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

[0013] In the separator according to one embodiment, the first water-soluble polymer is any one or more selected from the group consisting of metal polyacrylate salts, metal carboxymethylcellulose salts, and metal alginate salts, and the metal may include an alkali metal, an alkaline earth metal, or a combination thereof.

[0014] In the separator according to one embodiment, the first water-soluble polymer may have a weight average molecular weight of 2,000 to 100,000 g / mol.

[0015] In the separator according to one embodiment, the separator may include 1 to 20 parts by weight of the first water-soluble polymer with respect to 100 parts by weight of the inorganic particles.

[0016] In the separator according to one embodiment, the second water-soluble polymer may be poly(meth)acrylamide or a copolymer containing the same.

[0017] In the separator according to one embodiment, the copolymer may be a copolymer including a polymerization unit of a (meth)acrylamide-based monomer and a polymerization unit of a hydroxy group-containing (meth)acrylate-based monomer, a polymerization unit of a polyfunctional (meth)acrylamide-based monomer, or a combination thereof.

[0018] In the separator according to one embodiment, the second water-soluble polymer may have a weight average molecular weight of 100,000 to 2,000,000 g / mol.

[0019] In a separator according to an embodiment, the separator may include 0.1 to 10 parts by weight of a second water-soluble polymer with respect to 100 parts by weight of inorganic particles.

[0020] In a separator according to an embodiment, after leaving the separator at 150°C for 60 minutes, the thermal shrinkage rates in the MD direction and TD direction measured may be 2% or less.

[0021] A method for manufacturing a separator according to the present disclosure includes (S1) a step of manufacturing a slurry composition including a binder and inorganic particles, and (S2) a step of applying the slurry composition to at least one surface of a porous substrate to form an inorganic particle layer, and the binder may include a first water-soluble polymer including a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer.

[0022] In a method for manufacturing a separator according to an embodiment, the first water-soluble polymer is any one or more selected from the group consisting of metal polyacrylates, metal carboxymethyl celluloses, and metal alginates, and the metal may include an alkali metal, an alkaline earth metal, or a combination thereof.

[0023] In a method for manufacturing a separator according to an embodiment, the first water-soluble polymer may have a weight average molecular weight of 2,000 to 100,000 g / mol.

[0024] In a method for manufacturing a separator according to an embodiment, the second water-soluble polymer may be polyacrylamide or a copolymer including the same.

[0025] In a method for manufacturing a separator according to an embodiment, the copolymer may be a copolymer including a polymerization unit of a (meth)acrylamide-based monomer and a polymerization unit of a hydroxy group-containing (meth)acrylate-based monomer, a polyfunctional (meth)acrylamide-based monomer, or a combination thereof.

[0026] The electrochemical device according to the present disclosure may include a separator as described above.

Advantages of the Invention

[0027] The separator according to one embodiment of the present disclosure includes a specific combination of water-soluble polymers, effectively suppressing the decomposition reaction of the electrolyte, improving the performance of the electrochemical device, and ensuring excellent heat resistance and adhesiveness.

[0028] The electrochemical device according to one embodiment, by including the above-described separator, not only has the characteristic of reduced volume change of the electrochemical device, but also can have reduced resistance and significantly excellent life characteristics.

Mode for Carrying Out the Invention

[0029] The embodiments described in this specification may be modified into various other forms, and the technology according to one embodiment is not limited to the embodiments described below. Also, the embodiments of one embodiment are provided to more fully explain the present disclosure to those with average knowledge in the technical field.

[0030] Also, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

[0031] Also, the numerical ranges used in this specification include the lower limit value and the upper limit value, all values within that range, increments logically derived from the form and width of the defined range, all doubly limited values, and all possible combinations of the upper and lower limits of numerically defined ranges limited to different forms. In this specification, unless otherwise specified, values outside the numerical range that may occur due to experimental error or rounding of values are also included in the defined numerical range.

[0032] Furthermore, throughout the specification, unless otherwise indicated to the contrary, the use of the term "comprising" with respect to a certain component means not excluding other components, but further including other components.

[0033] In this specification, when a part such as a layer, film, region, plate, etc. is said to be "on" or "above" another part, this includes not only the case where it is "immediately above" the other part, but also the case where there are further other parts in between.

[0034] Terms such as first, second, etc. used in this specification can be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

[0035] As used in this specification, the "monomer polymerization unit" can mean the basic repeating unit of a polymer chain derived from the monomer.

[0036] In this specification, "(meth)acrylic" means acrylic and / or methacrylic.

[0037] In this specification, in the expression "substituted or unsubstituted", "substituted" means that one or more hydrogen atoms in the hydrocarbon are each independently replaced by the same or different substituents. Non-limiting examples of the substituents include deuterium, halogen group, hydroxy group, amino group, C1-C30 amine group, nitro group, C1-C30 silyl group, C1-C30 alkyl group, C1-C30 alkylsilyl group, C3-C30 cycloalkyl group, C1-C30 heterocycloalkyl group, C6-C30 aryl group, C1-C30 heteroaryl group, C1-C20 alkoxy group, C1-C10 trifluoroalkyl group or cyano group.

[0038] In this specification, "Dn" (n is a real number) means the particle size of particles corresponding to n% in terms of the integrated fraction based on volume. For example, "D50" means the particle size of particles corresponding to 50% of the integrated fraction based on volume. The Dn can be derived from the particle size distribution results obtained by sampling a sample in accordance with the KS A ISO 13320-1 standard for the inorganic particles to be measured and analyzing it using a Multisizer 4e Coulter counter manufactured by Beckman Coulter.

[0039] Conventional methods for suppressing electrolyte decomposition in batteries mainly involved adding an additive as one component into the electrolyte. However, such electrolyte additives were sensitive to moisture, difficult to store, expensive, in a form dissolved in the electrolyte, and had limitations in that they had an adverse effect on the performance of the cell.

[0040] Therefore, as a result of intensive research, the present inventors have found that when a separator containing a polymer using a metal carboxylate salt as a functional group and all (meth)acrylamide-based polymers as a binder is used in a battery, the above-mentioned limitations can be eliminated and electrolyte decomposition can be suppressed, leading to the invention of the present disclosure.

[0041] That is, the separator having an inorganic particle layer containing the binder according to the present disclosure can effectively suppress the decomposition reaction of the electrolyte, improve the performance of the electrochemical device without reducing it, and ensure excellent heat resistance and adhesiveness by the design of the specific polymer combination. In addition, it is possible to provide a battery having a characteristic of significantly reducing changes such as volume expansion of the electrochemical device over time, and it is possible to provide an effect that the resistance of the battery is reduced and it has significantly excellent life characteristics.

[0042] A separator according to one embodiment includes a porous substrate and an inorganic particle layer formed on at least one surface of the porous substrate, the inorganic particle layer including a binder and inorganic particles. The binder includes a first water-soluble polymer containing a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer. Here, the (meth)acrylamide-based polymer means a polymer containing a polymerization unit of a (meth)acrylamide-based monomer.

[0043] By including a mixed binder containing the first water-soluble polymer and the second water-soluble polymer, the separator solves the problems caused by electrolyte decomposition inhibitors added to conventional electrolytes, and effectively suppresses the decomposition reaction of the electrolyte, thereby significantly improving the performance of electrochemical elements such as lithium secondary batteries.

[0044] Specifically, by using a mixed binder containing a first water-soluble polymer containing a metal carboxylate group and a (meth)acrylamide-based second water-soluble polymer as the binder, the binder is stable in moisture and provides an environmentally friendly aqueous separator. A separator according to one embodiment can suppress the decomposition of the electrolyte inside the separator and further suppress the side reactions that occur by including such a binder. In addition, the separator has the advantages of significantly suppressing the decomposition reaction of the electrolyte and excellent heat resistance and adhesiveness. In the case of an electrochemical element using an electrolyte decomposition inhibitor added to the electrolyte, there is a demerit that the electrolyte decomposition inhibitor is dissolved in the electrolyte and affects the performance of the cell. On the other hand, an electrochemical element according to one embodiment can solve the conventional problem that the binder contained in the separator is not dissolved in the electrolyte and the electrolyte decomposition inhibitor is dissolved in the electrolyte and affects the performance of the cell. The electrochemical element can solve the conventional problems in this way and suppress electrolyte decomposition, and can have excellent resistance characteristics and life characteristics.

[0045] Hereinafter, each component of the separator according to the embodiment of the present disclosure will be described.

[0046] In one embodiment, the first water-soluble polymer is a polymer containing a metal carboxylate group. The first water-soluble polymer can be a homopolymer or a copolymer, and can contain a metal carboxylate group in the main chain and / or side chain.

[0047] The first water-soluble polymer is not particularly limited, and for example, it may be any one or more selected from the group consisting of metal salts of polyacrylic acid, metal salts of carboxymethyl cellulose, and metal salts of alginic acid.

[0048] In one embodiment, the metal of the metal carboxylate group may include an alkali metal, an alkaline earth metal, or a combination thereof, and specifically, it may be sodium or lithium.

[0049] In one embodiment, the polyethylene glycol equivalent weight average molecular weight of the first water-soluble polymer measured using gel permeation chromatography is 2,000 g / mol or more, 3,000 g / mol or more, 100,000 g / mol or less, 50,000 g / mol or less, 40,000 g / mol or less, 30,000 g / mol or less, 15,000 g / mol or less, or a value between the above numerical values. Specifically, the first water-soluble polymer may have a weight average molecular weight of 2,000 to 100,000 g / mol, 2,000 to 50,000 g / mol, 3,000 to 40,000 g / mol, 3,000 to 30,000 g / mol, or 3,000 to 15,000 g / mol.

[0050] For the separator according to one embodiment, when the weight average molecular weight of the first water-soluble polymer satisfies the above range, the electrolyte decomposition suppression characteristics, heat resistance, and adhesiveness can be further improved.

[0051] As one embodiment, the separator may include a first water-soluble polymer in an amount of 1 part by weight or more, 2 parts by weight or more, 5 parts by weight or more, 20 parts by weight or less, 15 parts by weight or less, or a value between the numerical values with respect to 100 parts by weight of the inorganic particles. Specifically, the separator may include 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 with respect to 100 parts by weight of the inorganic particles. When the content of the first water-soluble polymer in the separator according to one embodiment satisfies the above range, the electrolyte decomposition suppression characteristics, heat resistance, and adhesiveness can be further improved.

[0052] In a preferred embodiment, the separator may include 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 with respect to 100 parts by weight of the inorganic particles. When the content of the first water-soluble polymer satisfies the above range, it can be applied to a battery having more excellent performance.

[0053] The separator according to one embodiment can effectively suppress the decomposition reaction of the electrolyte by including a (meth)acrylamide-based second water-soluble polymer together with the above-described first water-soluble polymer, increase the adhesiveness between the porous base material and the inorganic particle layer, and improve the heat resistance at high temperatures.

[0054] The (meth)acrylamide-based second water-soluble polymer can be a homopolymer or a copolymer, and can be a homopolymer or a copolymer having (meth)acrylamide as a polymerization unit. As one embodiment, the second water-soluble polymer can be poly(meth)acrylamide or a copolymer containing the same. In one embodiment, the copolymer can be a block copolymer or a random copolymer, but the copolymer described in the present disclosure is a polymer obtained by mixing and polymerizing two or more monomers together and means a random copolymer.

[0055] As one embodiment, the copolymer containing the poly(meth)acrylamide may be a copolymer containing a polymerization unit of a (meth)acrylamide-based monomer, a polymerization unit of a hydroxy group-containing (meth)acrylate-based monomer, a polymerization unit of a polyfunctional (meth)acrylamide-based monomer, or a combination thereof.

[0056] The copolymer containing the poly(meth)acrylamide can contain a (meth)acrylamide-based monomer polymerization unit, or can contain a (meth)acrylamide-based monomer polymerization unit and a hydroxy group-containing (meth)acrylate-based monomer polymerization unit, or can contain a (meth)acrylamide-based monomer polymerization unit, a hydroxy group-containing (meth)acrylate-based monomer polymerization unit, and a polyfunctional (meth)acrylamide-based monomer polymerization unit.

[0057] Preferably, when the second water-soluble polymer is a copolymer containing a polymerization unit of a (meth)acrylamide-based monomer, a polymerization unit of a hydroxy group-containing (meth)acrylate-based monomer, and a polymerization unit of a polyfunctional (meth)acrylamide-based monomer, the effects intended in the present disclosure can be most preferably achieved, although more preferably but not limited thereto. That is, the separator according to one embodiment can further improve the electrolyte decomposition suppression characteristics, heat resistance, and adhesiveness by including the copolymer.

[0058] In one embodiment, the polymerization unit of the (meth)acrylamide-based monomer may include the structure of the following Chemical Formula 1.

[0059]

Chemical formula

[0060] In Chemical Formula 1, R 1 ~R 3 may each independently be hydrogen or a substituted or unsubstituted linear or branched C1-C6 alkyl group.

[0061] In one embodiment, the polymerized unit of the (meth)acrylate monomer containing a hydroxy group may include the structure of the following Chemical Formula 2.

[0062]

Chemical formula

[0063] In Chemical Formula 2, R 4 ~R 6 may each independently be hydrogen or a C1-C6 alkyl group, and L may be a linear or branched C1-C6 alkylene group.

[0064] The polymerized unit of the polyfunctional (meth)acrylamide monomer can be polymerized from the polyfunctional monomer represented by the following Chemical Formula 3 and generated.

[0065]

Chemical formula

[0066] In Chemical Formula 3, R 7 ~R 9 may each independently be hydrogen or a substituted or unsubstituted linear or branched C1-C6 alkyl group, R 10 may be a linear or branched C1-C10 hydrocarbon group, and a may be 2-6, preferably 2 or 3.

[0067] In the second water-soluble polymer according to one embodiment, the (meth)acrylamide-based monomer may be contained in an amount of 65 to 98 mol% or 70 to 95 mol%. The (meth)acrylic-based monomer containing a hydroxy group may be contained in an amount of 2 to 35 mol%, 3 to 30 mol%, or 5 to 25 mol%. The polyfunctional (meth)acrylamide-based monomer may be contained in an amount of 0.001 to 1 mol% or 0.01 to 0.5 mol%. Within the range of the above contents, when producing the second water-soluble polymer, sufficient adhesive strength can be obtained, a more remarkable effect can be obtained in terms of the high-temperature shrinkage rate, the decomposition reaction of the electrolyte can be effectively suppressed, and the suppression effect of side reactions caused by the decomposition products of the electrolyte can be further improved.

[0068] In one embodiment, the second water-soluble polymer may have a weight average molecular weight of 100,000 g / mol or more, 200,000 g / mol or more, 2,000,000 g / mol or less, 1,000,000 g / mol or less, 500,000 g / mol or less, or a value between the above numerical values. Specifically, the second water-soluble polymer may have a weight average molecular weight of 100,000 to 2,000,000 g / mol, 200,000 to 1,000,000 g / mol, or 200,000 to 500,000 g / mol. According to one embodiment, when the weight average molecular weight of the second water-soluble polymer satisfies the above range, the decomposition suppression characteristics, heat resistance, and adhesiveness of the electrolyte can be further improved. The weight average molecular weight is the polyethylene glycol equivalent average molecular weight measured using gel permeation chromatography.

[0069] As long as the second water-soluble polymer according to the above embodiment can be provided, the production method is not particularly limited. However, in one embodiment, the second water-soluble polymer may be provided by various known polymerization methods such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc.

[0070] In one embodiment, the second water-soluble polymer may be obtained by copolymerization reaction from a mixture containing the above monomer components and a polymerization initiator.

[0071] In one embodiment, the type of the polymerization initiator is not particularly limited as long as the copolymer can be obtained. In one embodiment, the polymerization initiator may be an azo-based initiator, a peroxide-based initiator, or a persulfate-based polymerization initiator such as potassium persulfate, sodium persulfate, or ammonium persulfate.

[0072] According to one embodiment, the second water-soluble polymer may be obtained by adding a polymerization initiator after raising the temperature to 50 to 90 °C or 60 to 80 °C and carrying out a polymerization reaction.

[0073] In one embodiment, after the polymerization reaction is completed, the temperature may be lowered to room temperature (20 ± 5 °C), and a basic solution or the like may be added to prepare an aqueous solution of the second water-soluble polymer adjusted to a neutral state.

[0074] In the separator, in one embodiment, the content of the second water-soluble polymer may be 0.1 part by weight or more, 0.5 part by weight or more, 1 part by weight or more, 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or a value between the above numerical values with respect to 100 parts by weight of the inorganic particles constituting the inorganic particle layer. Specifically, the second water-soluble polymer may be contained in an amount of 0.1 to 10 parts by weight, 0.5 to 5 parts by weight, or 1 to 3 parts by weight with respect to 100 parts by weight of the inorganic particles. When the content of the second water-soluble polymer in the separator according to one embodiment satisfies the above range, the electrolyte decomposition suppression characteristics, heat resistance, and adhesiveness can be further improved.

[0075] The separator according to one embodiment effectively suppresses the decomposition reaction of the electrolyte and has excellent heat resistance. According to one embodiment, after the separator is left at 150 °C for 60 minutes, the thermal shrinkage rates in the MD direction and TD direction measured may be 2% or less, 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.

[0076] In one embodiment, the porous substrate may be a polyolefin-based porous substrate such as polyethylene, polypropylene, or copolymers thereof, but is not limited thereto, and any porous substrate known as a porous substrate for a separator of an electrochemical element may be used. In one embodiment, the porous substrate may be manufactured as a film or a sheet, but is not particularly limited.

[0077] In one embodiment, 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 numerical values, and may be 1 to 100 μm, specifically 3 to 50 μm, more specifically 5 to 20 μm, and even more specifically 5 to 15 μm for the realization of a high-capacity battery. Although not limited thereto, the porous substrate may be manufactured by stretching.

[0078] In one embodiment, the porosity of the porous substrate may be 20 to 60%, specifically 30 to 60%, but is not limited thereto.

[0079] In one embodiment, the Gurley permeability 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 numerical values, and may be 50 to 500 sec / 100 cc, specifically 70 to 200 sec / 100 cc, but is not limited thereto. The Gurley permeability may be measured according to ASTM D726.

[0080] In one embodiment, the tensile strength in the width direction (TD, Transverse Direction) and the tensile strength in the machine direction (MD, Machine Direction) of the porous substrate are each independently 1000 kgf / cm 2 or more, 1500 kgf / cm 2 or more, 5000 kgf / cm 2The following can be a value below 4000 kgf / cm 2 or a value between the above numerical values, and can be 1000 - 5000 kgf / cm 2 , specifically 1500 - 4000 kgf / cm 2 , but is not limited thereto.

[0081] In one embodiment, the porous substrate may not substantially contain polar functional groups on its surface. A separator according to one embodiment includes a porous substrate that does not substantially contain polar functional groups together with a specific polymer combination as described above, whereby the electrolyte decomposition suppression characteristics can be further improved. Here, that the porous substrate substantially does not contain polar functional groups may mean that the porous substrate contains polar functional groups in an amount less than 1% by weight or less than 0.5% by weight based on the total weight of the porous substrate. Specifically, the porous substrate may be one that has not been subjected to hydrophilic surface treatment and into which polar functional groups have not been introduced. Non-limiting examples of the polar functional groups include carboxyl groups, aldehyde groups, hydroxy groups, etc., but are not particularly limited. The hydrophilic surface treatment may be, for example, corona discharge treatment or plasma discharge treatment.

[0082] In one embodiment, the inorganic particle layer may include a binder and inorganic particles, and may be a porous inorganic particle layer in which the inorganic particles are connected and fixed by the binder to form pores. In one embodiment, the inorganic particle layer is provided on at least one surface of the porous substrate, and may occupy an area fraction of 60% or more, 70% or more, 80% or more, or 90% or more 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.

[0083] In one embodiment, the inorganic particle layer may be coated on one or both surfaces of the porous substrate. When the inorganic particle layers are coated on both surfaces of the porous substrate, the thicknesses of the inorganic particle layers coated on one surface and the other surface may be the same as or different from each other. Although not particularly limited, in one embodiment, the thickness of the inorganic particle layer coated on one surface may be 0.01 μm or more, 0.2 μm or more, 0.5 μm or more, 15 μm or less, 10 μm or less, 5 μm or less, or a value between the numerical values. In a specific embodiment, 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 separator was measured using a caliper thickness measuring instrument. After stacking 10 separators, the thicknesses were measured at 5 different points of the 10-fold separator, and the average thickness of the 10-fold separator was derived. This value was also divided by 10 to derive the average thickness of the separator. The value obtained by subtracting the thickness of the porous substrate from the thickness of the separator was taken as the thickness of the inorganic particle layer. The thickness of the porous substrate was calculated by stacking 10 porous substrates only and performing the same measurement and calculation as the separator thickness measurement method.

[0084] As one embodiment, the inorganic particles are not limited as long as they are inorganic particles used in the technical field. As non-limiting examples, the inorganic particles may include one or more of metal hydroxides, metal oxides, metal nitrides, and metal carbides, or SiO 2 , SiC, MgO, Y 2 O 3 , Al 2 O 3 , CeO 2 , CaO, ZnO, SrTiO 3 , ZrO 2 , TiO 2 and AlO(OH). From the viewpoint of battery stability and the like, the inorganic particles may preferably be metal hydroxide particles such as boehmite.

[0085] The metal hydroxide is not particularly limited, and non-limiting examples include one or more of boehmite, aluminum hydroxide, and magnesium hydroxide. In one embodiment, when using the boehmite, for example, the specific surface area (BET) may be 10 m 2 / g or more, or 15 m 2 / g or more, but is not limited thereto.

[0086] In one embodiment, the inorganic particles may have an average diameter (D50) of 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 5 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or a value between the above numerical values. Specifically, it may be 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.

[0087] One embodiment includes: (S1) a step of manufacturing a slurry composition containing a binder and inorganic particles; and (S2) a step of applying the slurry composition to at least one surface of a porous substrate to form an inorganic particle layer. The binder includes a first water-soluble polymer containing a metal carboxylate group and a second water-soluble polymer of a (meth)acrylamide type, and a method for manufacturing a separator can be provided.

[0088] Hereinafter, each step of the method for manufacturing a separator according to the above embodiment will be described. Since the descriptions of the above-mentioned porous substrates, inorganic particle layers, inorganic particles, first water-soluble polymer, and second water-soluble polymer are as described above, specific descriptions are omitted.

[0089] In the step (S1), as the method for manufacturing the slurry composition, all ordinary methods known in the art may be applied without limitation. Although not particularly limited, according to non-limiting examples, the slurry may be manufactured by stirring to disperse the inorganic particles, or the aggregated inorganic particles may be dispersed using a ball mill.

[0090] The slurry composition contains inorganic particles, a first water-soluble polymer, a second water-soluble polymer, and a solvent. The solvent may be water, a lower alcohol such as ethanol, methanol, propanol, dimethylformamide, acetone, tetrahydrofuran, diethyl ether, methylene chloride, DMF, N-methyl-2-pyrrolidone, hexane, cyclohexane, or a mixture thereof, but is not necessarily limited thereto.

[0091] In one embodiment, the solid content of the slurry composition is not particularly limited, and may be, for example, 1 to 50% by weight, 5 to 30% by weight, or 10 to 30% by weight, but is not limited thereto.

[0092] In one embodiment, the slurry composition may include 70 to 95% by weight of inorganic particles, 1 to 20% by weight of the first water-soluble polymer, and 0.1 to 10% by weight of the second water-soluble polymer based on the total weight of the solid content. Specifically, it may include 80 to 95% by weight of inorganic particles, 2 to 15% by weight of the first water-soluble polymer, and 0.5 to 5% by weight of the second water-soluble polymer, but is not limited thereto.

[0093] In the step (S2), as a method for applying the slurry composition, all ordinary methods known in the art may be applied without limitation. By way of non-limiting example, roll coating, spin coating, dip coating, bar coating, die coating, slit coating, inkjet printing, and methods combining these may be applied. The applied slurry can be dried and formed as an inorganic particle layer. The drying for forming the inorganic particle layer is not particularly limited, but may be performed at 100°C or lower, or at 30 to 60°C.

[0094] In a specific embodiment, after drying to form the inorganic particle layer, a step of aging the porous substrate on which the inorganic particle layer is formed may be further included. Specifically, the aging may be performed at 50 to 150 °C or 60 °C to 120 °C, and the aging time may be 2 hours to 24 hours or 10 to 20 hours. More specifically, it may be performed for 10 to 15 hours in a temperature range of 70 to 120 °C. By the aging, the adhesiveness between the porous substrate and the inorganic particle layer can be increased, and the heat resistance at high temperatures can be further improved.

[0095] According to one embodiment, an electrochemical device including a separator according to one of the above-described embodiments can be provided. By including the separator as described above, the electrochemical device can have a reduced electrical resistance and significantly excellent life characteristics.

[0096] The electrochemical device may be any known energy storage device and is not particularly limited. As a non-limiting example, a lithium secondary battery may be mentioned. The lithium secondary battery is a known one, and since its configuration is also well-known, it will not be specifically described in the present disclosure.

[0097] A lithium secondary battery according to one embodiment may include the above-described separator between a positive electrode and a negative electrode. Here, the positive electrode and the negative electrode can be used without limitation as long as they are those usually used in lithium secondary batteries.

[0098] The separator according to one embodiment is usually completed by injecting an electrolyte by a general manufacturing method in which the negative electrode, the separator, and the positive electrode are arranged and assembled when used in a battery, and thus will not be described in more detail here.

[0099] Hereinafter, examples and experimental examples will be specifically illustrated and described below. However, the examples and experimental examples described later are only illustrative in part, and the technology described in this specification is not limited thereto.

[0100] First, the separator and the method for evaluating the characteristics of the secondary battery will be described.

[0101] [Weight-average molecular weight] The weight-average molecular weight is measured using GPC (manufactured by Tosoh, EcoSEC HLC-8320 GPC Reflective Index detector). The GPC column is Tskgel guard PWx, two TSKgel GMPWxl, and TSKgel G2500PWxl (7.8×300 mm). The solvent is 0.1M NaNO 3 aqueous solution, the standard is polyethylene glycol, and the analysis is performed at 40°C with a flow rate of 1 ml / min.

[0102] [Electrolyte decomposition inhibition characteristics of the separator] To evaluate the electrolyte decomposition inhibition characteristics of the separator, 0.8 g of the separator was impregnated into 10 g of an electrolyte in which 1M lithium hexafluorophosphate (LiPF 6 ) was dissolved in a solution containing 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. Then, 19 by 19F NMR analysis, the electrolyte impregnated with the separator was analyzed to confirm the degree of generation of decomposition products of the electrolyte typified by phosphine by-products and HF. Specifically, to quantify the electrolyte decomposition inhibition characteristics, 19 the integral value of the peak for HF in the 19F NMR analysis spectrum was calculated to measure the HF content.

[0103] [Thermal shrinkage rate of the separator] The thermal shrinkage rate of the separator is measured in accordance with ASTM D 1204, and in this case, it is measured by the following method. On the separator, grid points are marked at 2 cm intervals on a square with a side length of 10 cm. One side of this square is the transverse direction (TD), and the other side is the machine direction (MD). The test piece is positioned in the middle, and 5 sheets of paper are placed above and below the test piece respectively, and the four sides of the paper are wrapped with tape. The test piece wrapped with paper is left in a hot air drying oven at 150 °C for 60 minutes. Then, the test piece is taken out, the separator is observed with a camera, and the shrinkage rate in the machine direction of the following formula 1 and the shrinkage rate in the transverse direction of the following formula 2 are calculated.

[0104] [Formula 1] Shrinkage rate in the machine direction (%) = {(Length in the machine direction before heating - Length in the machine direction after heating) / Length in the machine direction before heating} × 100

[0105] [Formula 2] Shrinkage rate in the transverse direction (%) = {(Length in the transverse direction before heating - Length in the transverse direction after heating) / Length in the transverse direction before heating} × 100

[0106] [Adhesion of the separator] The separator is cut into a size of 50 mm in width × 50 mm in length and arranged so that the inorganic particle layer is on top. A black drawing paper (width 20 mm × length 150 mm × thickness 0.25 mm) with a coefficient of kinetic friction of 0.15 is placed on it, and after applying a predetermined pressure (200 g / cm 2 ), the black drawing paper is forcibly pulled out horizontally to check the degree of inorganic matter on the surface, and according to the degree of adhesion, it is discriminated from A / B / C / D / E / F by referring to the following grades.

[0107] A: None adhered B: A small amount of inorganic matter adhered C~F are the levels where both the binder and the inorganic matter are adhered, and the degree gets worse as it goes to F

[0108] [Initial performance of the secondary battery] To evaluate the initial performance of the secondary batteries manufactured by each of the examples and comparative examples, the resistance and discharge output of the secondary batteries were measured according to the following method, and based on Comparative Example 1, the performance of the batteries of the remaining examples and comparative examples was relatively evaluated.

[0109] After charging the secondary battery at 25 °C with 0.5C CC / CV (4.2V 0.05 cut-off (CUT-OFF)), the thickness of the battery was measured.

[0110] The secondary battery was charged at room temperature using a charge / discharge cycle device with CC-CV (Constant current-constant voltage) of 4.2V up to 4.2V and 0.05C, and then discharged at a current of 0.5C down to 2.7V. And the DC-IR (Direct Current Internal Resistance) was measured by the J-Pulse method at SOC (State of Charge) 60%.

[0111] The output characteristics of the secondary battery at room temperature when the SOC (State Of Charge) was 50% were measured by the HPPC (Hybrid Pulse Power Characterization by FreedomCar Battery Test Manual) method.

[0112] [Life characteristics] The secondary batteries manufactured according to each example and comparative example were charged at 4.2 V with a CC-CV (Constant current-constant voltage) using a charge / discharge cycle device and then discharged. The secondary battery was charged at a constant current of 0.5 C rate at 25 °C until the voltage reached 4.2 V, and then charged at a constant voltage until the current reached 0.01 C while maintaining 4.2 V. Next, during discharge, the cycle of discharging at a constant current of 0.5 C until the voltage reached 3.0 V was repeated 800 times. The resistance was measured by the J-Pulse method for DC-IR (Direct Current Internal Resistance), and then the resistance increase rate (ΔR) was calculated according to the following formula. Based on Comparative Example 1, the values of the remaining examples and comparative examples were relatively evaluated. The lower the numerical value, the lower the relative resistance increase rate.

[0113] ΔR (%) = (R 2 - R 1 ) / R 1 × 100

[0114] The R 1 is the initial resistance (mΩ) measured after the first cycle of each manufactured battery, and the R 2 is the resistance (mΩ) after 800 cycles.

[0115] Also, the capacity retention rate (ΔC) was calculated according to the following formula. Similarly, based on Comparative Example 1, the values of the remaining examples and comparative examples were relatively evaluated. The higher the numerical value, the higher the relative capacity retention rate.

[0116] ΔC (%) = (C 2 - C 1 ) / C 1 × 100

[0117] The C 1 is the initial discharge capacity (Ah) measured after the first cycle of each manufactured battery, and the C 2 is the discharge capacity (Ah) after 800 cycles.

[0118] [High-temperature storage stability] The secondary batteries manufactured according to each of the examples and comparative examples were stored in an oven at 60°C for 80 days, and then the DC-IR (Direct Current Internal Resistance) and discharge capacity were measured by the J-Pulse method described above. Thereafter, the resistance increase rate (ΔR') and the capacity retention rate (ΔC') were calculated according to the following formulas respectively, and based on Comparative Example 1, the values of the remaining examples and comparative examples were evaluated relatively. In the case of the resistance increase rate, the lower the numerical value, the lower the relative resistance increase rate, and in the case of the capacity retention rate, the higher the numerical value, the higher the relative capacity retention rate.

[0119] ΔR’(%)=(R 4 -R 3 ) / R 3 ×100

[0120] The R 3 is the initial resistance (mΩ) of each manufactured battery before oven storage, and the R 4 is the resistance (mΩ) after storage in an oven at 60°C for 80 days.

[0121] ΔC’(%)=(C 4 -C 3 ) / C 3 ×100

[0122] The C 3 is the discharge capacity (Ah) of each manufactured battery before oven storage, and the C 4 is the discharge capacity (Ah) after storage in an oven at 60°C for 80 days.

[0123] <Manufacturing Example 1> After replacing the 1.0 L flask with nitrogen, 1055 mmol of monomer components of acrylamide and 700 g of distilled water were added to the flask, and then the temperature was raised to 75°C. Then, as a polymerization initiator, 0.789 mmol of ammonium persulfate was further added to the flask, and the polymerization reaction of the mixture was carried out after sealing the flask. After carrying out the polymerization reaction for 12 hours, the sealed flask was opened to the atmosphere to lower the temperature to room temperature, 1 M sodium hydroxide solution was added to adjust the pH to 7, and a second water-soluble polymer aqueous solution was produced. Here, the weight-average molecular weight of the produced second water-soluble polymer was 280,000 g / mol.

[0124] <Production Example 2> A second water-soluble polymer aqueous solution was produced in the same manner as in Production Example 1, except that 878 mmol of acrylamide and 204 mmol of 2-hydroxyethyl methacrylate were used as monomer components. Here, the weight-average molecular weight of the produced second water-soluble polymer was 300,000 g / mol.

[0125] <Production Example 3> A second water-soluble polymer aqueous solution was produced in the same manner as in Production 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. Here, the weight-average molecular weight of the produced second water-soluble polymer was 250,000 g / mol.

[0126] <Example 1> Production of Slurry Composition To water, 90.35 wt% of boehmite (γ-AlO(OH)) with an average particle size (D50) of 0.6 μm, 8.64 wt% of sodium polyacrylate salt (Sigma-aldrich, Mw: 5,100 g / mol), and 1.01 wt% of the second water-soluble polymer produced in Production Example 1 were added based on the total weight of the solid content, and then stirred to produce a slurry composition with a solid content concentration of 25 wt%.

[0127] Production of Separator As the porous substrate, a polyethylene porous film with a thickness of 9 μm (porosity: 48%, Gurley permeability: 82 sec / 100 cc, tensile strength in the MD direction: 2020 kgf / cm 2 , tensile strength in the TD direction: 1950 kgf / cm 2 ) was used. Without surface treatment, the manufactured slurry composition was coated on both sides of the porous substrate to form an inorganic particle layer with a thickness of 2.0 μm each. After undergoing the step of aging the porous substrate provided with the inorganic particle layer at 80 °C for 12 hours, a separator was manufactured. The characteristics of the separator are summarized in Table 1 below.

[0128] Manufacture of secondary battery As the positive electrode active material, 94 wt% of LiCoO 2 , 2.5 wt% of polyvinylidene fluoride as the binder, 3.5 wt% of carbon black as the conductive agent were added to NMP (N-methyl-2-pyrrolidone) which is a solvent and stirred to produce a uniform positive electrode slurry. The manufactured positive electrode slurry was coated on an aluminum foil with a thickness of 30 μm, dried and calendered to produce a positive electrode with a total thickness of 150 μm. As the negative electrode active material, 95 wt% of artificial graphite, 3 wt% of an acrylic latex with a Tg of -52 °C as the binder, 2 wt% of CMC (carboxymethyl cellulose) as the thickener were added to water which is a solvent and stirred to produce a uniform negative electrode slurry. The manufactured negative electrode slurry was coated on a copper foil with a thickness of 20 μm, dried and calendered to produce a negative electrode with a total thickness of 150 μm. The manufactured positive electrode, negative electrode and separator were assembled into a pouch-type battery in a manner of stacking them between the positive electrode and the negative electrode. Then, the assembled battery for fusing the positive electrode, negative electrode and separator together was heat-sealed with a heat press machine at 80 °C and 1 MPa. Thereafter, 1 M of lithium hexafluorophosphate (LiPF6 ) After injecting the dissolved electrolyte, it was sealed to manufacture a secondary battery with a capacity of 2 Ah. The initial performance, life characteristics, and high-temperature storage stability of the secondary battery are summarized in Table 2 below.

[0129] <Example 2> A separator and a secondary battery were manufactured in the same manner as in Example 1, except that a slurry composition with a solid content concentration of 25 wt% was manufactured using 94.05 wt% of boehmite, 4.91 wt% of sodium polyacrylate salt, and 1.05 wt% of the second water-soluble polymer manufactured in Production Example 1 with respect to the total weight of the solid content. The characteristics of the separator and the secondary battery are summarized in Tables 1 and 2 below.

[0130] <Example 3> A separator and a secondary battery were manufactured in the same manner as in Example 2, except that the second water-soluble polymer manufactured in Production Example 2 was used instead of the second water-soluble polymer manufactured in Production Example 1. The characteristics of the separator and the secondary battery are summarized in Tables 1 and 2 below.

[0131] <Example 4> A separator and a secondary battery were manufactured in the same manner as in Example 2, except that the second water-soluble polymer manufactured in Production Example 3 was used instead of the second water-soluble polymer manufactured in Production Example 1. The characteristics of the separator and the secondary battery are summarized in Tables 1 and 2 below.

[0132] <Comparative Example 1> Manufacture of Slurry Composition Without using sodium polyacrylate salt, 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 manufactured in Production Example 1 were added to water with respect to the total weight of the solid content, and then stirred to manufacture a slurry with a solid content concentration of 25 wt%.

[0133] Separator Manufacture As the porous substrate, a polyethylene porous film with a thickness of 9 μm (porosity: 48%, Gurley permeability: 82 sec / 100 cc, tensile strength in the MD direction: 2020 kgf / cm 2 , tensile strength in the TD direction: 1950 kgf / cm 2 ) was used. Both sides of the porous substrate were treated by corona discharge (power density 2 W / mm) to introduce surface polar groups. At this time, the corona discharge treatment was carried out at a speed of 3 - 20 mpm (meter per minute). The manufactured slurry composition was coated on both sides of the porous substrate with the introduced surface polar groups, and an inorganic particle layer with a thickness of 2.0 μm was formed respectively. A separator was manufactured through the step of aging the porous substrate provided with the inorganic particle layer at 80 °C for 12 hours. The characteristics of the separator are summarized in Table 1 below.

[0134] Manufacture of secondary battery 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 summarized in Table 2 below.

[0135] <Comparative Example 2> A separator and a secondary battery were manufactured in the same manner as in Comparative Example 1 except that the second water-soluble polymer manufactured in Production Example 3 was used instead of the second water-soluble polymer manufactured in Production Example 1. The characteristics of the separator and the secondary battery are summarized in Table 1 and Table 2 below.

[0136] <Comparative Example 3> A slurry, a separator, and a secondary battery were manufactured in the same manner as in Example 1 except that polyvinyl alcohol (Sigma-aldrich, Mw: 180,000 g / mol) was used instead of the second water-soluble polymer of Production Example 1. The characteristics of the separator and the secondary battery are summarized in Table 1 and Table 2 below.

[0137] <Comparative Example 4> A slurry, a separator, and a secondary battery were produced in the same manner as in Example 1, except that polyvinylpyrrolidone (Sigma-aldrich, Mw: 55,000 g / mol) was used instead of the second water-soluble polymer in Production Example 1. The characteristics of the separator and the secondary battery are summarized in Tables 1 and 2 below.

[0138]

Table 1

[0139]

Table 2

[0140] Referring to Tables 1 and 2, the separators of Examples 1 to 4 can effectively suppress the decomposition reaction of the electrolyte by including the first water-soluble polymer and the second water-soluble polymer according to one embodiment as binders, and after being left at 150°C for 60 minutes, the thermal shrinkage rates in the MD direction and TD direction measured are 1.5% or less, and it can be confirmed that they have excellent heat resistance. It can also be confirmed that the adhesive strength to the yellow cardboard is A and the adhesiveness has been significantly improved. In addition, the secondary batteries of Examples 1 to 4 can be confirmed to have improved initial performance, life characteristics, and high-temperature stability by including the separator according to one embodiment.

[0141] Moreover, for the batteries of Examples 2 to 4, more excellent performance was confirmed by using the first water-soluble polymer in the range of 1 to 9 parts by weight with respect to 100 parts by weight of the inorganic particles.

[0142] In addition, Examples 3 and 4 show more excellent electrolyte decomposition suppression characteristics, heat resistance, and adhesiveness by using, as a binder, a second water-soluble polymer produced by further including a hydroxy group-containing (meth)acrylate monomer and / or a polyfunctional (meth)acrylamide monomer other than the (meth)acrylamide monomer. The battery to which this was applied also showed more excellent initial performance, life characteristics, and high-temperature stability.

[0143] On the other hand, in Comparative Examples 1 and 2, sodium polyacrylate salt was not used as a binder, and as a result, the heat resistance decreased compared to the examples, an excessive amount of decomposition by-products of the electrolyte was generated, the amount of gas generated by electrolyte decomposition increased, and it was confirmed that the initial performance, life characteristics, and high-temperature stability of the battery decreased.

[0144] In Comparative Examples 3 and 4, instead of using a polyacrylamide-based polymer, another type of polymer was used as a binder, and as a result, it was confirmed that not only the characteristics of suppressing electrolyte decomposition, heat resistance, and adhesiveness of the separator but also the initial performance, life characteristics, and high-temperature stability of the secondary battery decreased compared to the examples.

[0145] As described above, in this specification, the present disclosure has been described by way of specific matters and limited examples, but this is provided to contribute to a more general understanding of the present disclosure, and the present disclosure is not limited to the above-described examples, and various modifications and variations are possible from such descriptions for those having ordinary knowledge in the field to which the present disclosure pertains.

Claims

1. A porous substrate; an inorganic particle layer formed on at least one surface of the porous substrate and including a binder and inorganic particles; The separator, wherein the binder comprises a first water-soluble polymer containing a metal carboxylate group and a second water-soluble polymer of a (meth)acrylamide type.

2. the first water-soluble polymer is at least one selected from the group consisting of a metal salt of polyacrylic acid, a metal salt of carboxymethyl cellulose, and a metal salt of alginic acid; 10. The separator of claim 1, wherein the metal comprises an alkali metal, an alkaline earth metal, or a combination thereof.

3. The separator according to claim 1 , wherein the first water-soluble polymer has a weight average molecular weight of 2,000 to 100,000 g / mol.

4. 2. The separator according to claim 1, comprising 1 to 20 parts by weight of the first water-soluble polymer per 100 parts by weight of the inorganic particles.

5. The separator according to claim 1 , wherein the second water-soluble polymer is poly(meth)acrylamide or a copolymer containing poly(meth)acrylamide.

6. 6. The separator according to claim 5, wherein the copolymer contains polymerized units of a (meth)acrylamide-based monomer, polymerized units of a hydroxyl group-containing (meth)acrylate-based monomer, polymerized units of a polyfunctional (meth)acrylamide-based monomer, or a combination thereof.

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

8. 2. The separator according to claim 1, comprising 0.1 to 10 parts by weight of the second water-soluble polymer per 100 parts by weight of the inorganic particles.

9. 2. The separator according to claim 1, wherein the separator has a thermal shrinkage rate of 2% or less in the MD and TD directions measured after being left at 150°C for 60 minutes.

10. (S1) preparing a slurry composition containing a binder and inorganic particles; (S2) applying the slurry composition to at least one surface of a porous substrate to form an inorganic particle layer; The method for producing a separator, wherein the binder comprises a first water-soluble polymer containing a metal carboxylate group and a second water-soluble (meth)acrylamide-based polymer.

11. the first water-soluble polymer is at least one selected from the group consisting of a metal salt of polyacrylic acid, a metal salt of carboxymethyl cellulose, and a metal salt of alginic acid; The method of claim 10 , wherein the metal comprises an alkali metal, an alkaline earth metal, or a combination thereof.

12. The method for producing a separator according to claim 10, wherein the first water-soluble polymer has a weight average molecular weight of 2,000 to 100,000 g / mol.

13. The method for manufacturing a separator according to claim 10 , wherein the second water-soluble polymer is polyacrylamide or a copolymer containing polyacrylamide.

14. 14. The method for producing a separator according to claim 13, wherein the copolymer contains polymerization units of a (meth)acrylamide-based monomer, polymerization units of a hydroxyl group-containing (meth)acrylate-based monomer, polymerization units of a polyfunctional (meth)acrylamide-based monomer, or a combination thereof.

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

Images