Separator for electrochemical device and electrochemical device comprising same

Abstract

The present invention relates to a separator for an electrochemical device, the separator comprising a coating layer that includes, as a binder, a copolymer comprising i) repeating units derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both monomers, ii) a repeating unit derived from an acrylic monomer having an amide group, and iii) repeating units derived from a silane-based monomer, a monomer having a silanol group, or both monomers, wherein the copolymer may exhibit excellent adhesion to inorganic particles due to including, in particular, iii) the repeating units derived from the silane-based monomer, the monomer having a silanol group, or both monomers, and thus the separator for an electrochemical device and including the binder exhibits excellent adhesion to an electrode and has a low thermal shrinkage ratio.

Description

Separator for an electrochemical device and an electrochemical device including the same

[0001] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same.

[0002] This application is a priority claim application for Korean Patent Application No. 10-2024-0129373 filed on September 24, 2024, and all contents disclosed in the specification of said application are incorporated into this application by reference.

[0003] Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions; recently, lithium-ion batteries, which offer high energy density and voltage, long cycle life, and applicability to various fields, are widely used.

[0004] Among the components of such an electrochemical device, the separator may comprise a polymer substrate having a porous structure located between the anode and the cathode. The separator isolates the anode and the cathode to prevent an electrical short circuit between the two electrodes, while simultaneously allowing the electrolyte and ions to pass through. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, porosity, and thermal shrinkage rate, can affect the performance and safety of the electrochemical device.

[0005] Therefore, to enhance the physical properties of such separation membranes, various methods are being attempted to improve the properties of the coating layer by adding a coating layer to a porous polymer substrate and adding various materials to the coating layer. For example, inorganic materials may be added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic materials or hydrates may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0006] Within the coating layer, inorganic particles can be connected to other inorganic particles by a polymer binder to form an interstitial volume, and lithium ions can move through the interstitial volume. That is, the coating layer containing a polymer binder and inorganic particles serves to prevent thermal shrinkage of the separator while simultaneously facilitating the movement of lithium ions through the separator.

[0007] Meanwhile, the poly(meth)acrylic acid binder, the polyacrylamide binder having an amide group, or the copolymer binder of (meth)acrylic acid and acrylamide used as the polymer binder have excellent heat resistance, and thus have the advantage of effectively reducing the thermal shrinkage problem of the porous polymer substrate when used together with the inorganic particles. However, the adhesive strength of the binder is low at room temperature or high temperature, and as the temperature rises, the adhesive strength of the binder weakens. Consequently, there was a problem in that the dry thermal shrinkage rate and / or wet thermal shrinkage rate of the separator for an electrochemical device containing the binder in the coating layer decreased at high temperatures.

[0008] A technical problem according to one aspect of the present invention is to provide a separator for an electrochemical device in which the dry thermal shrinkage rate and the wet thermal shrinkage rate at high temperatures are simultaneously improved, and an electrochemical device equipped with the same.

[0009] A separator for an electrochemical device according to the first aspect of the present invention is,

[0010] porous polymer substrate; and

[0011] A coating layer disposed on at least one surface of the above-mentioned porous polymer substrate and comprising inorganic particles and a binder, and

[0012] The above binder comprises i) a repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, ii) a repeating unit derived from an acrylic monomer having an amide group, and iii) a copolymer comprising a silane monomer, a monomer having a silanol group, or a repeating unit derived from both of these monomers.

[0013] The second aspect of the present invention is, in the first aspect,

[0014] The molar ratio of the above i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers and the above ii) repeating unit derived from an acrylic monomer having an amide group is 1:3 or more and 1:5 or less.

[0015] A third aspect of the present invention is, in the first or second aspect,

[0016] The molar ratio of the above i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers and the above iii) silane monomer, monomer having a silanol group, or repeating unit derived from both of these monomers is 1:0.01 or greater and 1:0.1 or less.

[0017] The fourth aspect of the present invention is, in any one of the first to third aspects,

[0018] The above (meth)acrylate monomer is one or more selected from the group consisting of sodium (meth)acrylate, potassium (meth)acrylate, lithium (meth)acrylate, and ammonium (meth)acrylate.

[0019] The fifth aspect of the present invention is, in any one of the first to fourth aspects,

[0020] The above acrylic monomer having an amide group is acrylamide, methylacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, NN-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-ethylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, It is one or more selected from the group consisting of N-methoxyethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide.

[0021] The sixth aspect of the present invention is, in any one of the first to fifth aspects,

[0022] The above silane monomer is one or more selected from the group consisting of vinyl trimethoxysilane, vinyl bismethoxyethoxysilane, vinyl triethoxysilane, 3-(meth)acryl-oxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyl triacetoxysilane, and the monomer having the silanol group may be a hydrolyzate of the above silane monomer.

[0023] The seventh aspect of the present invention is, in any one of the first to sixth aspects,

[0024] The content of the binder is 4 parts by weight or more and 20 parts by weight or less, based on 100 parts by weight of the total weight of the coating layer.

[0025] The eighth aspect of the present invention is, in any one of the first to seventh aspects,

[0026] The above copolymer has a weight average molecular weight of 100,000 g / mol or more and 200,000 g / mol or less.

[0027] The ninth aspect of the present invention is, in any one of the first to eighth aspects,

[0028] The content of the above inorganic particles is 80 parts by weight or more and 90 parts by weight or less, based on 100 parts by weight of the total weight of the coating layer.

[0029] The tenth aspect of the present invention is, in any one of the first to ninth aspects,

[0030] The thickness of the coating layer is 0.5 μm or more and 2 μm or less.

[0031] The eleventh aspect of the present invention relates to an electrochemical device, wherein

[0032] It comprises an anode; a cathode; and a separator for an electrochemical device according to any one of the first to tenth aspects, wherein the separator for the electrochemical device is interposed between the anode and the cathode.

[0033] The separator for an electrochemical device according to the present invention comprises a copolymer, which is a binder used in the coating layer together with inorganic particles, comprising i) repeating units derived from (meth)acrylic acid monomers, (meth)acrylic acid salt monomers, or both of these monomers, and ii) repeating units derived from acrylic monomers having amide groups, and additionally iii) repeating units derived from silane monomers, monomers having silanol groups, or both of these monomers. Accordingly, the above-mentioned iii) component of the copolymer can strongly bond to the surface of the porous polymer substrate or the surface of the inorganic particles through intermolecular forces such as hydrogen bonding with the inorganic particles and the porous polymer substrate, and can also bond to the electrode surface. Consequently, the separator for an electrochemical device according to the present invention, in which the above-mentioned copolymer binder is included in the coating layer, exhibits improved high-temperature thermal shrinkage rates in both dry and wet states.

[0034] Hereinafter, each component of the present invention is described in more detail so that a person skilled in the art to which the present invention pertains can easily implement it; however, this is merely an example, and the scope of the rights of the present invention is not limited by the following.

[0035] In the present specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0036] In this specification, when a component is described as being disposed on "one side," this means that, unless specifically stated otherwise, other components may be disposed therein, without excluding other components from being disposed in between.

[0037] In this specification, "electrochemical device" may mean a primary battery, a secondary battery, or a supercapacitor, etc. More specifically, the electrochemical device may be a lithium-ion secondary battery and may be pouch-type, cylindrical-type, prismatic-type, or coin-type, but the specific shape is not limited thereto.

[0038] In this specification, "electrode" collectively refers to "anode" and "cathode," and may mean a material having conductivity without causing chemical changes in an electrochemical device, on which an electrode active material is coated and dried. The types of the material and the electrode active material are not limited, as long as they can be used in an electrochemical device.

[0039] In this specification, "separator" generally refers to a functional separator in which a porous coating layer comprising inorganic particles and a binder is formed on at least one surface of a porous polymer substrate, such as a polyolefin substrate or a nonwoven fabric. Additionally, the separator has porous characteristics containing a plurality of pores and acts as a porous ion-conducting barrier that blocks electrical contact between a cathode and an anode in an electrochemical device while allowing ions to pass through.

[0040] In this specification, the characteristic of having porosity or pores means that a gaseous and / or liquid fluid can pass from one side to the other side of the object through a structure in which the object includes a plurality of voids or pores and said voids or pores are interconnected.

[0041] In this specification, "porous polymer substrate" may refer to a porous membrane having a plurality of pores formed therein, which electrically insulates the positive electrode and the negative electrode to prevent a short circuit. For example, if the electrochemical device is a lithium secondary battery, the porous polymer substrate may be an ion-conducting barrier that blocks electrical contact between the positive electrode and the negative electrode while allowing lithium ions to pass through. At least some of the pores may form a three-dimensional network communicating the surface and the interior of the porous polymer substrate, and a fluid may pass through the porous polymer substrate through the pores.

[0042] In this specification, "the diameter of the particle (D 50 )" or “Particle size (D 50)" refers to the diameter of the particle corresponding to the 50% point of the cumulative volume in the cumulative particle size distribution for the particle being measured. The above diameter can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to calculate the particle size distribution by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. By calculating the particle diameter at the point that is 50% of the cumulative distribution of the number of particles according to diameter in the measuring device, the average particle size (D) 50 ) can be measured.

[0043] In this specification, “(meth)acrylic acid monomer” encompasses both acrylic acid monomers and methacrylic acid monomers. Additionally, “(meth)acrylic acid salt monomer” encompasses both acrylic acid salt monomers and methacrylic acid salt monomers.

[0044] In this specification, an acrylic monomer having an amide group refers to an acrylic monomer having an amide group in a side chain. That is, it refers to a monomer containing an acrylamide structure within the molecule. For example, the acrylamide monomer may be represented by a chemical formula such as CH2=CHC(O)ND1D2, where D1 and D2 are each independently hydrogen, nitrogen, oxygen, or a substituted or unsubstituted hydrocarbon group having 1 to 10 carbon atoms. Furthermore, the acrylamide monomer is not limited to the chemical formula structure described above (CH2=CHC(O)ND1D2), and may have additional functional groups attached to the carbon double bond.

[0045] In this specification, “silane monomer” refers to a monomer having a hydrolyzable silane group, specifically a silane monomer having at least one alkoxy group bonded to a silicon atom. For example, the silane monomer may be represented by a chemical formula such as CH2=CHSi(OA)3, wherein A is a hydrocarbyl group containing 1 to 8 carbon atoms. During the polymerization process, the silane monomer may be hydrolyzed by water or steam, so that the alkoxy group is substituted with a silanol group. Additionally, “monomer having a silanol group” refers to a monomer having a silanol group in a side chain.

[0046]

[0047] The present invention will be described in more detail below.

[0048] The present invention provides a separator for an electrochemical device.

[0049] According to one embodiment of the present invention, the separator for an electrochemical device comprises a porous polymer substrate and a coating layer disposed on at least one surface of the porous polymer substrate and comprising inorganic particles and a binder, wherein the binder comprises i) repeating units derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both monomers, ii) repeating units derived from an acrylic monomer having an amide group, and iii) repeating units derived from a silane monomer, a monomer having a silanol group, or both monomers. The copolymer may be formed by copolymerizing the monomers in the form of a random copolymer, a graft copolymer, or a block copolymer, and specifically, the copolymer may be a random copolymer.

[0050] A binder comprising a polyacrylic acid binder or a copolymer containing i) a repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, and ii) a repeating unit derived from an acrylic monomer having an amide group, has the advantage of being able to lower the thermal shrinkage rate of the separator in the dry state because the binder itself undergoes minimal deformation at high temperatures due to its high glass transition temperature. However, there was a problem in that the above binder had poor binding strength with inorganic materials in the wet state, making it difficult to improve the thermal shrinkage rate in the wet state. Specifically, for example, in the case of polyacrylic acid, it has hydrophilic properties and a high glass transition temperature, so it has the advantage of not causing swelling due to the electrolyte. However, since polyacrylic acid has poor binding strength with inorganic particles, there is a problem in that it is difficult to improve the thermal shrinkage problem of the separator in the wet state when applied to the coating layer alone. On the other hand, polymers of acrylic monomers containing amide groups, such as polyacrylamide, have the advantage of high rigidity and a high glass transition temperature, resulting in minimal deformation at high temperatures. However, since their binding strength with inorganic particles is poor—similar to that of polyacrylic acid—there is a problem in that it is difficult to improve the thermal shrinkage of the separator in a wet state when applied to a coating layer as a binder, either alone or in a copolymer form with acrylic acid monomers.

[0051] The separator for an electrochemical device according to the present invention comprises a copolymer, which is a binder used in the coating layer together with inorganic particles, comprising i) repeating units derived from (meth)acrylic acid monomers, (meth)acrylic acid salt monomers, or both of these monomers, and ii) repeating units derived from acrylic monomers having amide groups, and additionally iii) repeating units derived from silane monomers, monomers having silanol groups, or both of these monomers. Accordingly, the above-mentioned iii) component of the copolymer can strongly bond to the surface of the porous polymer substrate or the surface of the inorganic particles through intermolecular forces such as hydrogen bonding with the inorganic particles and the porous polymer substrate, and can also bond to the electrode surface. Consequently, the separator for an electrochemical device according to the present invention, in which the above-mentioned copolymer binder is included in the coating layer, exhibits improved high-temperature thermal shrinkage rates in both dry and wet states.

[0052] Specifically, when a silane monomer is applied to an aqueous solvent such as water to form a coating layer, it contains silanol groups, and thus possesses silanol groups just like a monomer having silanol groups. A copolymer having silanol groups can strongly bond to the surface of a porous polymer substrate, the surface of an inorganic particle, or the surface of an electrode through intermolecular forces such as hydrogen bonding. Consequently, the separator for an electrochemical device according to the present invention, which includes the copolymer binder in the coating layer, has a low thermal shrinkage rate in both dry and wet states.

[0053] In addition, the binder may be a solution-type binder. Since the binder has a solution-type form, it can adhere to inorganic particles and porous polymer substrates over a wider surface area within the coating layer, thereby having the advantage of effectively lowering the thermal shrinkage rate of the separator compared to particulate binders. In this case, silane-based monomers having silanol groups or silanol groups of monomers having silanol groups can bond to the surface of the porous polymer substrate, the surface of inorganic particles, or the surface of the electrode through intermolecular forces such as hydrogen bonding by hydrolysis.

[0054] Meanwhile, silicon-containing silicon acrylate monomers do not contain silane groups or silanol groups, unlike the silane monomers mentioned above. Therefore, even if the silicon acrylate monomer is copolymerized with an acrylic monomer and an acrylamide monomer, such copolymers cannot interact strongly with the surface of inorganic particles and porous polymer substrates. Consequently, copolymer binders containing the silicon acrylate monomer, acrylic monomer, and acrylamide monomer may have poor heat resistance in a wet state.

[0055] According to one embodiment of the present invention, the molar ratio of i) a repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, and ii) a repeating unit derived from an acrylic monomer having an amide group may be 1:3 or more and 1:5 or less. Specifically, the molar ratio of i) a repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, and ii) a repeating unit derived from an acrylic monomer having an amide group may be 1:3 or more, 1:3.5 or more, or 1:4 or more, and may also be 1:5 or less, 1:4.5 or less, or 1:4 or less. When the content of each monomer included in the copolymer satisfies the above range, i) repeating units derived from (meth)acrylic acid monomers, (meth)acrylic acid salt monomers, or both of these monomers, which have a high glass transition temperature and low shape deformation, and ii) repeating units derived from acrylic monomers having amide groups, can both be sufficiently present in the copolymer, and the separator for an electrochemical device containing the copolymer binder in the coating layer may have a low thermal shrinkage rate in the dry state.

[0056] According to one embodiment of the present invention, the molar ratio of the (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers and the iii) silane monomer, monomer having a silanol group, or repeating unit derived from both of these monomers may be 1:0.01 or more and 1:0.1 or less. Specifically, the molar ratio of the above i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers and the above iii) silane monomer, monomer having a silanol group, or repeating unit derived from both of these monomers may be 1:0.01 or more, 1:0.02 or more, 1:0.03 or more, 1:0.04 or more, or 1:0.05 or more, and may also be 1:0.1 or less, 1:0.09 or less, 1:0.08 or less, 1:0.07 or less, 1:0.06 or less, 1:0.05 or less, 1:0.04 or less, or 1:0.03 or less. When the content of each monomer included in the copolymer satisfies the above range, the iii) silane-based monomer, the monomer having a silanol group, or the repeating unit derived from both of these monomers can be sufficiently included in the copolymer, so the interaction between the copolymer and the inorganic particles can be excellent. Accordingly, the copolymer binder can have excellent adhesion to the inorganic particles and the porous polymer substrate. Accordingly, a separator for an electrochemical device containing the copolymer binder in the coating layer can have a low thermal shrinkage rate at high temperatures and in wet conditions.

[0057] In summary, the molar ratio of i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers, ii) repeating unit derived from an acrylic monomer having an amide group, and iii) repeating unit derived from a silane monomer, a monomer having a silanol group, or both of these monomers in the copolymer may be 1: 3 or more and 5 or less: 0.01 or more and 0.1 or less. When the content of each monomer included in the copolymer satisfies the above range, i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating units derived from both of these monomers, which are effective for improving adhesion in a dry state, and ii) repeating units derived from acrylic monomers having amide groups, and iii) silane monomers, monomers having silanol groups, or repeating units derived from both of these monomers, which are effective for improving adhesion in a wet state, are present in a balanced manner, thereby enabling improvement in heat shrinkage rate in both dry and wet states.

[0058] i) Among the repeating units derived from (meth)acrylate monomers, (meth)acrylate salt monomers, or both monomers included in the copolymer according to the present invention, the (meth)acrylate salt monomer may be one or more selected from the group consisting of sodium (meth)acrylate, potassium (meth)acrylate, lithium (meth)acrylate, and ammonium (meth)acrylate.

[0059] According to one embodiment of the present invention, the acrylic monomer having an amide group ii) is acrylamide, methylacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, NN-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-ethylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, It may be one or more selected from the group consisting of N-methoxyethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide.

[0060] According to one embodiment of the present invention, the silane monomer is one or more selected from the group consisting of vinyl trimethoxysilane, vinyl bismethoxyethoxysilane, vinyl triethoxysilane, 3-(meth)acryl-oxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyl triacetoxysilane, and the monomer having the silanol group may be a hydrolyzate of the silane monomer.

[0061] According to one embodiment of the present invention, the content of the binder may be 4 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the total weight of the coating layer. Specifically, the content of the binder in the coating layer may be 4 parts by weight or more, 8 parts by weight or more, or 12 parts by weight or more based on 100 parts by weight of the total weight of the coating layer, and may also be 20 parts by weight or less, 18 parts by weight or less, 16 parts by weight or less, 14 parts by weight or less, or 12 parts by weight or less. When the content of the binder in the coating layer satisfies the above range, the binder may be sufficiently present in the coating layer, so the separator for an electrochemical device in which the coating layer is disposed on one surface of a porous polymer substrate may have a uniformly low thermal shrinkage rate in both dry and wet states.

[0062] According to one embodiment of the present invention, the copolymer may have a weight-average molecular weight of 100,000 g / mol or more and 200,000 g / mol or less. Specifically, the weight-average molecular weight of the copolymer may be 100,000 g / mol or more, 110,000 g / mol or more, 120,000 g / mol or more, 130,000 g / mol or more, 140,000 g / mol or more, or 150,000 g / mol or more, and may also be 200,000 g / mol or less, 190,000 g / mol or less, 180,000 g / mol or less, 170,000 g / mol or less, 160,000 g / mol or less, 150,000 g / mol or less, or 140,000 g / mol or less. When the weight-average molecular weight of the copolymer satisfies the above range, the copolymer may have a sufficient length to effectively prevent the problem of the inorganic particles detaching from the porous polymer substrate by being attached together to the inorganic particles and the porous polymer substrate. Accordingly, a separator for an electrochemical device in which a coating layer containing the copolymer as a binder is disposed on one side of a porous polymer substrate may have a low thermal shrinkage rate in both dry and wet conditions.

[0063] According to one embodiment of the present invention, the content of the inorganic particles may be 80 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the total weight of the coating layer. Specifically, the content of the inorganic particles may be 80 parts by weight or more, 82 parts by weight or more, 84 parts by weight or more, or 86 parts by weight or more based on 100 parts by weight of the total weight of the solids of the composition for forming the coating layer, and may also be 90 parts by weight or less, 88 parts by weight or less, or 86 parts by weight or less. When the content of the inorganic particles satisfies the above range, the inorganic particles can be sufficiently included in the coating layer, so the problem of thermal shrinkage of the porous polymer substrate in the separator for an electrochemical device can be minimized.

[0064] According to one embodiment of the invention, the inorganic particles are within the operating voltage range of an electrochemical element (e.g., Li / Li). + Oxidation and / or reduction reactions may not occur at a standard of 0 V to 5 V. Specifically, the inorganic particles are BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 It may be one or more selected from the group consisting of )O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, boehmite, aluminum peroxide, zinc-tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4) and antimony pentoxide (Sb2O5). Among these, boehmite or alumina may be particularly selected.

[0065] According to one embodiment of the present invention, the inorganic particle has a diameter (D 50 The diameter may be 200 nm or more and 1 μm or less. Specifically, the inorganic particles may have a diameter of 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or more, and may also have a diameter of 1 μm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, or 500 nm or less. When the diameter of the inorganic particles satisfies the above range, there may be sufficient spacing between the inorganic particles packed within the coating layer, and accordingly, the porosity of the coating layer may be high, and the resistance of the separator may be low.

[0066] According to one embodiment of the present invention, the thickness of the coating layer may be 0.5 μm or more and 2 μm or less. Specifically, the thickness of the coating layer may be 0.5 μm or more, 0.7 μm or more, or 0.9 μm or more, and may also be 2 μm or less, 1.8 μm or less, 1.6 μm or less, 1.4 μm or less, 1.2 μm or less, or 1 μm or less. When the thickness of the coating layer satisfies the above range, lithium ions can pass through the coating layer more smoothly due to the low coating layer thickness, and accordingly, the separator for the electrochemical device has the advantage of having low resistance. Furthermore, since the total thickness of the separator for the electrochemical device including the coating layer may also be low, the electrochemical device including the separator for the electrochemical device may contain a relatively large amount of electrode active material, and accordingly, the energy density of the electrochemical device may also be high.

[0067] According to one embodiment of the present invention, the porosity of the coating layer may be 30 volume% or more and 50 volume% or less. Specifically, the porosity of the coating layer may be 30 volume% or more, 35 volume% or more, or 40 volume% or more, and may also be 50 volume% or less, 45 volume% or less, or 40 volume% or less. When the porosity of the coating layer satisfies the above range, sufficient pores may exist in the coating layer, allowing lithium ions to move smoothly through the pores, and accordingly, the resistance of the separator for an electrochemical device may be low. In addition, compared to the case where the porosity of the coating layer is excessively high and there are excessively many pores within the coating layer, the separator for an electrochemical device according to the present invention may have excellent mechanical strength.

[0068] According to one embodiment of the present invention, the porous polymer substrate may be a porous membrane having a plurality of pores formed therein, which electrically insulates the positive electrode and the negative electrode to prevent a short circuit. For example, when the electrochemical device is a lithium secondary battery, the porous polymer substrate may be an ion-conducting barrier that blocks electrical contact between the positive electrode and the negative electrode while allowing lithium ions to pass through. At least some of the pores may form a three-dimensional network communicating the surface and the interior of the porous polymer film, and a fluid may pass through the porous polymer substrate through the pores.

[0069] The porous polymer substrate described above may be a material that is physically and chemically stable with respect to an electrolyte, which is an organic solvent. For example, the porous polymer substrate may include, but is not limited to, resins such as polyolefins including polyethylene, polypropylene, and polybutylene, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof. Preferably, a polyolefin resin may be used. Polyolefin resins are suitable for manufacturing electrochemical devices with higher energy density because they can be processed to a relatively thin thickness and facilitate the application of a composition for forming a coating layer.

[0070] The porous polymer substrate may have a single-layer or multi-layer structure. The porous polymer substrate may include two or more polymer resin layers with different melting points (Tm) to provide a shutdown function during high-temperature runaway of the battery. For example, the porous polymer film may include a polypropylene layer with a relatively high melting point and a polyethylene layer with a relatively low melting point. Preferably, the porous polymer substrate may have a three-layer structure laminated in the order of polypropylene, polyethylene, and polypropylene. The polyethylene layer may prevent thermal runaway of the battery by shutting down the pores as it melts as the temperature of the battery rises above a predetermined temperature.

[0071] According to one embodiment of the present invention, the thickness of the porous polymer substrate may be 6 μm or more and 15 μm or less. Specifically, the thickness of the porous polymer film may be 6 μm or more, 8 μm or more, or 10 μm or more, and may also be 15 μm or less, 13 μm or less, 11 μm or less, or 9 μm or less. By controlling the thickness of the porous polymer substrate within the above-described range, the volume of the electrochemical device can be minimized while electrically insulating the anode and the cathode, thereby increasing the amount of active material included in the electrochemical device.

[0072] According to one embodiment of the present invention, the porous polymer substrate has an average diameter (D 50It may include pores having a diameter of 0.01 μm or more and 1 μm or less. Specifically, the average diameter of the pores included in the porous polymer substrate may be 0.01 μm or more, 0.02 μm or more, 0.03 μm or more, or 0.04 μm or more, and may also be 1 μm or less, 0.09 μm or less, 0.08 μm or less, 0.07 μm or less, or 0.06 μm or less. Preferably, the pore size may be 0.02 μm or more and 0.06 μm or less. By controlling the pore size of the porous polymer substrate within the above-described range, the air permeability and ion conductivity of the entire separation membrane can be controlled.

[0073] The porous polymer substrate may have an air permeability of 10 s / 100cc or more and 100 s / 100cc or less. Specifically, the air permeability of the porous polymer substrate may be 10 s / 100cc or more, 20 s / 100cc or more, 30 s / 100cc or more, 40 s / 100cc or more, or 50 s / 100cc or more, and may also be 100 s / 100cc or less, 90 s / 100cc or less, 80 s / 100cc or less, 70 s / 100cc or less, 60 s / 100cc or less, or 50 s / 100cc or less. Preferably, the air permeability of the porous polymer substrate may be 50 s / 100cc or more and 70 s / 100cc or less. When the air permeability of the porous polymer substrate is within the range described above, the air permeability of the manufactured separator can be provided within a range suitable for securing the output and cycle characteristics of the electrochemical device.

[0074] The above air permeability (s / 100cc) refers to the time (in seconds) required for 100cc of air to pass through a porous polymer substrate or membrane of a predetermined area under constant pressure. The above air permeability may be measured using a Gurley densometer in accordance with ASTM D 726-58, ASTM D726-94, or JIS-P8117. For example, using a Gurley 4110N instrument, air at a pressure of 0.304 kPa or 1.215 kN / m 2 100cc of air under water pressure is 1 square inch (or 6.54 cm²) 2 The time it takes for ) to pass through a sample can be measured. For example, using the Asahi Seiko EG01-55-1MR instrument, the time it takes for 100cc of air to pass through a 1 square inch sample under a constant pressure of 4.8 inches of water at room temperature can be measured.

[0075] The porous polymer substrate may have a porosity of 10 volume% or more and 70 volume% or less. Specifically, the porosity of the porous polymer substrate may be 10 volume% or more, 20 volume% or more, 30 volume% or more, or 40 volume% or more, and may also be 70 volume% or less, 60 volume% or less, or 50 volume% or less. Preferably, the porosity of the porous polymer substrate may be 40 volume% or more and 60 volume% or less. When the porosity of the porous polymer substrate is within the range described above, the ionic conductivity of the manufactured separator may be provided within a range suitable for securing the output and cycle characteristics of the electrochemical device.

[0076] The above-described porosity refers to the ratio of the volume of pores to the total volume of each, in the coating layer and the porous polymer substrate. The porosity can be measured by methods known in the art. For example, it can be measured by the BET (Brunauer Emmett Teller) measurement method using nitrogen gas adsorption, the capillary flow porometer, or the water or mercury infiltration method.

[0077] The present invention provides an electrochemical device.

[0078] The above electrochemical device may include the separator for the electrochemical device described above.

[0079] According to one embodiment of the present invention, the electrochemical device comprises an anode, a cathode, and a separator for the electrochemical device, and the separator for the electrochemical device may be interposed between the anode and the cathode. In the electrochemical device according to one embodiment of the present invention, details that overlap with the description of the separator for the electrochemical device are omitted.

[0080] The above-mentioned electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept that encompasses primary batteries and secondary batteries. The above-mentioned secondary batteries are capable of charging and discharging and refer to lithium secondary batteries, nickel-cadmium batteries, nickel-hydrogen batteries, etc. The above-mentioned lithium secondary batteries use lithium ions as ion conductors, and examples include, but are not limited to, non-aqueous electrolyte secondary batteries containing a liquid electrolyte, all-solid-state batteries containing a solid electrolyte, lithium polymer batteries containing a gel polymer electrolyte, and lithium metal batteries using lithium metal as the negative electrode.

[0081] As the above-described electrochemical device includes the separator for the electrochemical device of the present invention, the adhesion between the separator for the electrochemical device and the electrode can be excellent, and accordingly, there is an advantage that the decrease in safety due to the detachment of the separator can be minimized even when the electrochemical device is operated for a long period of time.

[0082] According to one embodiment of the present invention, the positive electrode may comprise a positive electrode current collector and a positive electrode active material layer comprising a positive electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The positive electrode active material is a layered compound such as a lithium manganese complex oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn 1-x M x It may comprise a lithium manganese complex oxide represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which part of the Li of the chemical formula is substituted with alkaline earth metal ions; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0083] According to one embodiment of the present invention, the cathode may comprise a cathode current collector and a cathode active material layer comprising a cathode active material, a conductive material, and a binder resin on at least one surface of the current collector. The cathode may comprise carbon such as lithium metal oxide, non-graphitizable carbon, or graphite-based carbon as the cathode active material; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함하는 것일 수 있다.

[0084] According to one embodiment of the present invention, the conductive material may be, for example, any one selected from the group consisting of graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whiskers, conductive metal oxide, activated carbon, and polyphenylene derivative, or a mixture of two or more of these conductive materials. More specifically, it may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more of these conductive materials.

[0085] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used.

[0086] According to one embodiment of the present invention, the binder resin may be a polymer commonly used in the industry for electrodes. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include acetatepropionate), cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose, but are not limited thereto.

[0087] According to one embodiment of the present invention, the anode slurry for manufacturing the anode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (N-methylpyrrolidone, ADC-01, LG Chem).

[0088] According to one embodiment of the present invention, the electrochemical element may further include an electrolyte, and the electrolyte is A + B - As a salt with a structure like that, A + is Li + , Na + , K + It may include alkali metal cations such as or ions composed of combinations thereof. In addition, B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - A salt comprising an anion such as or a combination thereof may be dissolved or dissociated in an organic solvent comprising propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone, or a mixture thereof, but is not limited thereto.

[0089] One embodiment of the present invention may provide a battery module comprising a battery including the electrochemical element as a unit cell, a battery pack comprising the battery module, and a device comprising the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool that moves by receiving power from a battery motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) or an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0090] According to one embodiment of the present invention, the electrochemical device may form a cylindrical secondary battery by interposing a separator for the electrochemical device between the positive electrode and the negative electrode. In this case, the separator, the positive electrode, and the negative electrode may be stacked in the form of an electrode assembly having a separator / positive electrode / separator / negative electrode structure or a positive electrode / separator / negative electrode / separator structure and then wound. The positions of the positive electrode and the negative electrode may be interchanged. The electrode assembly stacked as described above may be inserted into a cylindrical can after being bound to a winding core and crimped to be manufactured into a cylindrical secondary battery.

[0091] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0092]

[0093] Examples and Comparative Examples

[0094] Manufacture of binders

[0095] Copolymer binders were prepared with different types and contents of monomers as shown in Table 1 below.

[0096] <Preparation Example 1>

[0097] A copolymer binder was prepared containing acrylic acid (AA), acrylamide (AM), and vinyl trimethoxysilane (SM) monomers in a molar ratio of 1:4:0.05.

[0098] <Preparation Example 2>

[0099] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that 3-acryl-oxypropyl trimethoxysilane (SM) was used instead of vinyl trimethoxysilane in Preparation Example 1.

[0100] <Preparation Example 3>

[0101] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that the copolymer was prepared such that the molar ratio of the monomers in the copolymer satisfies 1:4:0.025.

[0102] <Preparation Example 4>

[0103] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that the copolymer was prepared such that the molar ratio of the monomers in the copolymer satisfies 1:4:0.25.

[0104] <Comparative Preparation Example 1>

[0105] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that the copolymer was prepared without using the vinyl trimethoxysilane in Preparation Example 1.

[0106] <Comparative Preparation Example 2>

[0107] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that the vinyl trimethoxysilane was not used in Preparation Example 1, and the copolymer was prepared such that the molar ratio of the acrylic acid and acrylamide monomers was 1:0.7.

[0108] <Comparative Preparation Example 3>

[0109] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that the vinyl trimethoxysilane was not used in Preparation Example 1, and the copolymer was prepared such that the molar ratio of the acrylic acid and acrylamide monomers satisfied 1:0.25.

[0110] <Comparative Preparation Example 4>

[0111] A copolymer binder was prepared in the same manner as in Preparation Example 1, except that Poly(dimethylsiloxane), monomethacrylate terminated (SA: Silicone acrylate) was used instead of vinyl trimethoxysilane in Preparation Example 1.

[0112] Classification Monomer Content (Molar Ratio) AA AM SM SA Weight Average Molecular Weight (g / mol) Copolymer Binder Preparation Example 1 140.05-130,000 Preparation Example 2 140.05-140,000 Preparation Example 3 140.025-130,500 Preparation Example 4 140.25-150,000 Comparative Preparation Example 114--130,000 Comparative Preparation Example 2 10.7--140,000 Comparative Preparation Example 3 10.25--130,000 Comparative Preparation Example 4 14-0.05130,500

[0113] The weight-average molecular weight of Table 1 was measured using GPC.

[0114] Manufacturing of separators for electrochemical devices

[0115] <Example 1>

[0116] A polyethylene film (thickness 10 μm, air permeability 54 s / 100cc) was prepared as a porous polymer substrate.

[0117] Boehmite powder as inorganic particles (particle diameter (D 50 ): 500 nm) was prepared. As a binder, the binder of Preparation Example 1 above was prepared, as a thickener, sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem Co.) was prepared, and as a dispersant, a maleic acid-based dispersant was prepared. The prepared inorganic particles, binder, thickener, and dispersant were added to water in a weight ratio of 86:12:1:1, and then the inorganic particles were crushed and dispersed to prepare a composition for forming a coating layer.

[0118] A separator for an electrochemical device was manufactured by applying the composition for forming the coating layer to one surface of the porous polymer substrate using a doctor blade in a bar coating method and drying it with a heat gun at 50°C to form a coating layer on one surface of the porous polymer substrate.

[0119] At this time, based on a total weight of 100 parts by weight of the coating layer, the content of the binder was 12 parts by weight and the content of the inorganic particles was 86 parts by weight. In addition, the porosity of the coating layer was 40 volume% and the thickness of the coating layer was 1.5 μm.

[0120] <Examples 2 to 4 and Comparative Examples 1 to 4>

[0121] In the above Example 1, the separator membranes for electrochemical devices of Examples 2 to 4 and Comparative Examples 1 to 4 were prepared by using the binders of Preparation Examples 2 to 4 and Comparative Examples 1 to 4 instead of the binder of Preparation Example 1.

[0122] The physical properties of the separators for electrochemical devices of the examples and comparative examples are shown in Tables 2 and 3 below, respectively.

[0123]

[0124] Experimental Example

[0125] (1) Check the dry shrinkage rate of the membrane

[0126] The separator membranes for electrochemical devices of the above examples and comparative examples were each prepared as specimens measuring 5 cm × 5 cm. After storing the prepared specimens in a 180°C convection oven for 30 minutes, the thermal shrinkage rates in the MD (Machine Direction) and TD (Transverse Direction) directions were each calculated according to [(length of the initial specimen - length after storage at @180°C / 0.5h) / (length of the initial specimen)] × 100 (%).

[0127] (2) Check the wet shrinkage rate of the membrane

[0128] The separators of the above examples and comparative examples were prepared as specimens measuring 5 cm × 5 cm and each was inserted into an aluminum pouch measuring 7 cm × 10 cm. 1 g of the following electrolyte was injected into the pouch, and the pouch was sealed.

[0129] As the electrolyte, a solvent was used in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a weight ratio of 3 / 7, and 2 wt% vinylene carbonate (VC) and the lithium salt LiPF61 M were added as additives. After storing the sealed pouch in a 140°C convection oven for 30 minutes, the separator was removed, and the thermal shrinkage rates in the MD direction and TD direction were calculated according to [(length of the initial specimen - length after storage at 140°C for 0.5h) / (length of the initial specimen)] × 100 (%). The experimental results are shown in Tables 2 and 3 below.

[0130] Classification Example 1 Example 2 Example 3 Example 4 Porous Polymer Substrate Air Permeability (s / 100cc) 5 4 5 4 5 4 5 Thickness (μm) 10 10 10 10 Coating Layer Binder Content (WH) 12 12 12 12 Inorganic Content (WH) 8 6 8 6 8 6 6 Single-sided / Double-sided Double-sided Double-sided Porosity (Volume %) 4 0 3 8 3 7 3 Thickness (μm) 1.5 1.5 1.5 1.5 Separator Thickness (μm) 13.1 1 3.0 1 3.0 1 3.1 Dry Heat Shrinkage @ 180℃ / 0.5h (MD(%) / TD(%)) 2 / 1 3 / 2 3 / 16 / 4 Wet Heat Shrinkage @ 140℃ / 0.5h (MD(%) / TD(%)) 3 / 2 7 / 4 6 / 5 9 / 9

[0131] Classification Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Porous Polymer Substrate Air Permeability (s / 100cc) 5 4 5 4 5 4 5 Thickness (μm) 10 10 10 10 Coating Layer Binder Content (WH) 12 12 12 12 Inorganic Content (WH) 8 6 8 6 8 6 Single-sided / Double-sided Double-sided Double-sided Double-sided Porosity (Volume %) 4 0 3 4 3 5 3 Thickness (μm) 1.5 1.5 1.5 1.5 Separator Thickness (μm) 13.0 13.1 13.0 12.9 Dry Heat Shrinkage @ 180℃ / 0.5h (MD(%) / TD(%)) 4 / 3 6 / 5 8 / 6 7 / 6 Wet Heat Shrinkage @ 140℃ / 0.5h (MD(%) / TD(%)) 10 / 8 14 / 9 16 / 11 25 / 17

[0132] As shown in Tables 2 and 3 above, it can be confirmed that the separator membranes for electrochemical devices of Comparative Examples 1 to 3, which contain copolymer binders of acrylic monomers and acrylamide monomers, have low adhesion between the coating layer and the porous polymer substrate, resulting in a significantly high thermal shrinkage rate in the wet state. In contrast, the separator membranes for electrochemical devices of the Examples have a coating layer containing copolymer binders of acrylic monomers, acrylamide monomers, and silane monomers disposed on both sides of the porous polymer substrate, which can be confirmed to have a uniformly low thermal shrinkage rate in both the dry state and the wet state. In particular, in the case of Examples 1 to 3, which satisfy a molar ratio of acrylic monomers and silane monomers of 1:0.01 or more and 0.1 or less, it can be seen that the thermal shrinkage rate of the separator membrane is even lower.

[0133] In addition, the separator for an electrochemical device of Comparative Example 4, in which a copolymer binder of an acrylic monomer, an acrylamide monomer, and a silicon acrylate monomer is included in the coating layer, has reduced adhesion between the coating layer and the porous polymer substrate due to the silicon acrylate monomer in the copolymer, and it can be confirmed that the thermal shrinkage rate in the wet state is significantly higher compared to Comparative Examples 1 to 3.

[0134] From this, it can be confirmed that the separator for an electrochemical device according to the present invention achieves the effect of improving both the thermal shrinkage rate in the dry state and the thermal shrinkage rate in the wet state through the copolymer binder described above.

Claims

1. Porous polymer substrate; and A coating layer disposed on at least one surface of the above-mentioned porous polymer substrate and comprising inorganic particles and a binder, and A separator for an electrochemical device, wherein the binder comprises i) a repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, ii) a repeating unit derived from an acrylic monomer having an amide group, and iii) a copolymer comprising a silane monomer, a monomer having a silanol group, or a repeating unit derived from both of these monomers.

2. In Paragraph 1, A separator for an electrochemical device, wherein the molar ratio of the above i) repeating unit derived from a (meth)acrylic acid monomer, a (meth)acrylic acid salt monomer, or both of these monomers, and the above ii) repeating unit derived from an acrylic monomer having an amide group is 1:3 or more and 1:5 or less.

3. In Paragraph 1, A separator for an electrochemical device, wherein the molar ratio of the above i) (meth)acrylic acid monomer, (meth)acrylic acid salt monomer, or repeating unit derived from both of these monomers, and the above iii) silane monomer, monomer having a silanol group, or repeating unit derived from both of these monomers is 1:0.01 or greater and 1:0.1 or less.

4. In Paragraph 1, The above (meth)acrylate salt monomer is one or more selected from the group consisting of sodium (meth)acrylate, potassium (meth)acrylate, lithium (meth)acrylate, and ammonium (meth)acrylate, for use as a separator in an electrochemical device.

5. In Paragraph 1, The above acrylic monomer having an amide group is acrylamide, methylacrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di(n-butyl)(meth)acrylamide, N,N-di(t-butyl)(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, NN-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-ethylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, N-methoxymethyl(meth)acrylamide, A separator for an electrochemical device, comprising one or more selected from the group consisting of N-methoxyethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide.

6. In Paragraph 1, A separator for an electrochemical device, wherein the silane-based monomer is one or more selected from the group consisting of vinyl trimethoxysilane, vinyl bismethoxyethoxysilane, vinyl triethoxysilane, 3-(meth)acryl-oxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyl triacetoxysilane, and the monomer having a silanol group is one or more hydrolysates selected from the group consisting of vinyl trimethoxysilane, vinyl bismethoxyethoxysilane, vinyl triethoxysilane, 3-(meth)acryl-oxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, and vinyl triacetoxysilane.

7. In Paragraph 1, A separator for an electrochemical device, wherein the content of the binder is 4 parts by weight or more and 20 parts by weight or less based on 100 parts by weight of the total weight of the coating layer.

8. In Paragraph 1, The above copolymer is a separator for an electrochemical device having a weight average molecular weight of 100,000 g / mol or more and 200,000 g / mol or less.

9. In Paragraph 1, A separator for an electrochemical device, wherein the content of the above-mentioned inorganic particles is 80 parts by weight or more and 90 parts by weight or less, based on 100 parts by weight of the total weight of the coating layer.

10. In Paragraph 1, A separator for an electrochemical device having a coating layer thickness of 0.5 μm or more and 2 μm or less.

11. A positive electrode; a negative electrode; and a separator for an electrochemical device according to any one of claims 1 to 10, comprising The above electrochemical device is an electrochemical device in which a separator is interposed between the anode and the cathode.