Separator for electrochemical device and electrochemical device comprising same

Abstract

A separator for an electrochemical device of the present invention comprises: a porous polymer substrate; a coating layer that is provided on at least one surface of the porous polymer substrate and includes a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles; and an adhesive layer including a second acrylic polymer binder on the coating layer, wherein the adhesive layer forms a pattern having a constant coverage on the coating layer.

Description

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

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0133067 filed September 30, 2024 and Korean Patent Application No. 10-2025-0141143 filed September 29, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0002] The present invention relates to a separator for an electrochemical device and an electrochemical device including the same.

[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] A lithium secondary battery may include an electrode assembly manufactured with a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes, and the electrode assembly may be manufactured by housing it in a case together with an electrolyte.

[0005] Meanwhile, the separator of a lithium secondary battery prevents electrical contact between the positive and negative electrodes while enabling the movement of lithium ions between the electrodes, playing a crucial role in the safety and performance of the battery.

[0006] The present invention provides a separator for an electrochemical device having a resistance improvement effect by including a hybrid polymer binder in the coating layer and controlling the coverage of the adhesive layer, and an electrochemical device including the same.

[0007] However, the present invention is not limited to the features mentioned above, and other unmentioned features will be clearly understood by those skilled in the art from the following description.

[0008] One embodiment of the present invention provides a separator for an electrochemical device comprising: a porous polymer substrate; a coating layer provided on at least one surface of the porous polymer substrate and comprising a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles; and an adhesive layer comprising a second acrylic polymer binder on the coating layer, wherein the adhesive layer forms a pattern having a certain coverage on the coating layer.

[0009] The thickness of the above porous polymer substrate may be about 8 μm or more and 15 μm or less.

[0010] The thickness of the coating layer may be about 1 μm or more and 3 μm or less.

[0011] The first acrylic polymer binder may be in an amount of about 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer.

[0012] The above-mentioned hybrid polymer binder may be in an amount of about 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer.

[0013] The above-mentioned hybrid polymer binder may include a fluorine copolymer and an acrylic copolymer.

[0014] The above fluorine copolymer may be a copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP).

[0015] The content of the hexafluoropropylene (HFP) may be about 5% by weight or more and 20% by weight or less with respect to 100% by weight of the above fluorinated copolymer.

[0016] The above second acrylic polymer binder may be in an amount of about 80 parts by weight or more and 95 parts by weight or less per 100 parts by weight of the adhesive layer.

[0017] The adhesive layer forming the pattern on the coating layer may be distributed with a coverage of approximately 0% or more and 30% or less of the surface area of ​​the coating layer.

[0018] The thickness of the adhesive layer may be about 0.2 μm or more and 1 μm or less.

[0019] The resistance change rate of the above separator may be about 20% or less.

[0020] The wet adhesion strength of the above separator may be approximately 8 gf / 20mm or more and 20 gf / 20mm or less.

[0021] One embodiment of the present invention provides an electrochemical device comprising a separator for an electrochemical device located between the anode and the cathode.

[0022] A separator for an electrochemical device according to one embodiment of the present invention includes a hybrid polymer binder in the coating layer and can minimize the rate of change in resistance by controlling the coverage of the adhesive layer.

[0023] An electrochemical device according to one embodiment of the present invention includes a hybrid polymer binder in the coating layer and controls the coverage of the adhesive layer so that the rate of change in resistance can be minimized without reducing the adhesive strength even after electrolyte impregnation.

[0024] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0025] FIG. 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0026] Figure 2 is an SEM image of the membrane surface of Example 1 according to one embodiment of the present invention.

[0027] Figure 3 is an SEM image of the membrane surface of Example 2 according to one embodiment of the present invention.

[0028] Figure 4 is an SEM image of the membrane surface of Comparative Example 1 according to one embodiment of the present invention.

[0029] In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention.

[0030] In this 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.

[0031] In this specification, "A and / or B" means "A and B, or A or B".

[0032] In this specification, "about," "approximately," and "substantially" are used to mean a range of numerical values ​​or degrees or approximations thereof, taking into account inherent manufacturing and material tolerances, and are used to prevent an infringer from unfairly exploiting the disclosure in which precise or absolute figures provided to aid in understanding the invention are mentioned.

[0033] In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components.

[0034] In this specification, the characteristic of having 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 pores and said pores are interconnected.

[0035] In this specification, the separator has porous characteristics including a plurality of pores and acts as a porous ion-conducting barrier that blocks electrical contact between the cathode and the anode in an electrochemical device while allowing ions to pass through.

[0036] In this specification, "Wet state" may mean a state in which the separator is impregnated with at least a portion of the electrolyte, and "Dry state" may mean a dry state in which the separator is not impregnated by the electrolyte.

[0037] In this specification, "durability" may mean a property in which the binder does not swell or deform when in contact with an electrolyte and exhibits adhesive strength or mechanical strength as its original physical properties.

[0038] Among the components of 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.

[0039] 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.

[0040] 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. For example, a coating layer containing a polymer binder and inorganic particles serves to prevent or inhibit thermal shrinkage of the separator, while simultaneously facilitating the movement of lithium ions through the separator.

[0041] Meanwhile, acrylic polymer binders are used in these coating layers to improve adhesion and durability. However, when these acrylic polymer binders are introduced into the coating layer of a lithium secondary battery, they may swell in the electrolyte, which can reduce adhesion and act as resistors, potentially causing an increase in battery resistance and a decrease in performance.

[0042] Considering the problems associated with the introduction of such acrylic polymer binders into the separator, the present invention provides a separator capable of improving resistance and adhesion even when impregnated with an electrolyte.

[0043] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. The drawings may be exaggerated, omitted, or schematically illustrated to explain or emphasize the contents of an embodiment of the present invention.

[0044] FIG. 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0045] One embodiment of the present invention comprises a separator (100) for an electrochemical device, comprising: a porous polymer substrate (110); a coating layer (130) provided on at least one surface of the porous polymer substrate and comprising a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles; and an adhesive layer (150) comprising a second acrylic polymer binder on the coating layer, wherein the adhesive layer forms a pattern on the coating layer.

[0046] The above-described separator (100) for an electrochemical device includes a porous polymer substrate (110). As described above, by including the porous polymer substrate (110) for the electrochemical device separator (100), it is possible to block electrical contact while allowing lithium ions to pass through, and at the same time, implement a shutdown function at an appropriate temperature. The shutdown function is a function that prevents or suppresses thermal runaway by blocking the current flow through the separator blocking the pores when the battery overheats. When the internal temperature of the battery rises above a certain temperature, the separator melts and blocks the pores, thereby blocking contact between the positive and negative electrodes and stopping the current flow.

[0047] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured using a polyolefin-based resin as a base resin. Examples of polyolefin-based resins include polyethylene, polypropylene, polypentene, etc., and may include one or more of these. A porous separator having a plurality of pores manufactured using such a polyolefin-based resin as a base resin can provide a shutdown function at an appropriate temperature.

[0048] According to one embodiment of the present invention, the weight-average molecular weight of the polyolefin resin may be about 500,000 to 2 million. By controlling the weight-average molecular weight of the polyolefin resin within the above-described range, the compression resistance of the separator can be improved. Furthermore, when using a mixture of different types of polyolefin resins or forming a separator with a multilayer structure made of different types of polyolefin resins, the weight-average molecular weight of the polyolefin resin can be calculated by adding the weight-average molecular weights according to the content ratio of each polyolefin resin.

[0049] In the present specification, the weight-average molecular weight (Mw) may be measured by gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies), and according to one embodiment, the measurement conditions may be set as follows.

[0050] - Column: PL Olexis (Polymer Laboratories)

[0051] - Solvent: TCB (Trichlorobenzene)

[0052] - Flow rate: 1.0 ml / min

[0053] - Sample concentration: 1.0 mg / ml

[0054] - Injection volume: 200 µl

[0055] - Column temperature: 160 ℃

[0056] - Detector: Agilent High Temperature RI detector

[0057] - Standard: Polystyrene (corrected by a cubic function)

[0058] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) in which a polyolefin-based resin is mixed with a plasticizer (diluent) at a high temperature to form a single phase, the polymer material and the plasticizer are separated during the cooling process, the plasticizer is extracted to form pores, and then stretched and heat-set.

[0059] According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the porous polymer substrate (110) can be easily manufactured by a person skilled in the art to meet the scope of the present invention by adjusting the mixing ratio of the plasticizer, the stretching ratio, and the heat-setting treatment temperature.

[0060] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) may be about 8 μm or more and 15 μm or less. For example, the thickness of the porous polymer substrate (110) may be about 8 μm or more and 14 μm or less, 8 μm or more and 13 μm or less, 8 μm or more and 12 μm or less, 8 μm or more and 11 μm or less, or 9 μm or more and 10 μm or less, and according to one embodiment, it may be 9 μm. By controlling the thickness of the porous polymer substrate (110) within the above-described range, the energy density of the battery can be improved.

[0061] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) can be measured by a contact measurement method using a thickness gauge (Mitutoyo, VL-50S-B).

[0062] According to one embodiment of the present invention, the coating layer (130) is provided on at least one surface of the porous polymer substrate (110). As described above, by including the coating layer (130) provided on at least one surface of the porous polymer substrate (110) in the separator (100) for the electrochemical device, the heat resistance of the separator (100) is improved, mechanical properties are improved, and the separator shrinks at high temperatures, thereby preventing or suppressing the occurrence of an electrical short circuit in the electrode.

[0063] According to one embodiment of the present invention, the coating layer (130) comprises a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles. As described above, by including the first acrylic polymer binder, the hybrid polymer binder, and inorganic particles, the coating layer (130) improves the heat resistance of the separator (100), improves mechanical properties, prevents or suppresses the occurrence of an electrical short circuit in the electrode due to shrinkage of the separator (100) at high temperatures, forms pores within the coating layer, and suppresses swelling even after electrolyte impregnation, thereby improving the resistance of the secondary battery.

[0064] According to one embodiment of the present invention, the coating layer (130) may be formed by binding inorganic particles to a first acrylic polymer binder and a hybrid polymer binder and accumulating them within the layer. The pores within the coating layer may originate from the interstitial volume, which is the empty space between the inorganic particles.

[0065] According to one embodiment of the present invention, the coating layer (130) may include a plurality of pores. For example, the coating layer (130) may be a porous coating layer. The coating layer (130) may be a porous coating layer that includes a plurality of pores inside. As described above, by the coating layer (130) including a plurality of pores, it is possible to physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0066] According to one embodiment of the present invention, the coating layer (130) may be provided on both sides of the porous polymer substrate (110). As described above, by including the coating layer (130) provided on both sides of the porous polymer substrate (110) in the electrochemical device separator (100), the heat resistance of the separator (100) can be improved and the resistance can be improved. Meanwhile, the present invention is not limited thereto, and the coating layer (130) may be provided on one side of the porous polymer substrate (110).

[0067] According to one embodiment of the present invention, the thickness of the coating layer (130) may be about 1 μm or more and 3 μm or less. For example, the thickness of the coating layer (130) may be about 1 μm or more and 2 μm or less. By controlling the thickness of the coating layer (130) within the above-described range, the heat resistance and resistance characteristics of the separator can be improved, and furthermore, the battery resistance and cycle performance can also be maintained at an appropriate level.

[0068] In one embodiment of the present invention, the thickness of the coating layer (130), etc., can be measured by applying a contact-type thickness gauge. For example, the contact-type thickness gauge may use the VL-50S-B from Mitutoyo.

[0069] According to one embodiment of the present invention, the inorganic particles usable in the coating layer (130) are not particularly limited as long as they are electrochemically stable. For example, the inorganic particles usable in one embodiment of the present invention are within the operating voltage range of the electrochemical element to which they are applied (e.g., Li / Li + It is not particularly limited as long as oxidation and / or reduction reactions do not occur at a standard of 0 V to 5 V.

[0070] According to one embodiment of the present invention, the inorganic particles are boehmite, BaTiO3, Pb(Zr,Ti)O3(PZT), and 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 Examples include 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, aluminum peroxide, zinc-tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), etc., and may include one or more of these.

[0071] According to one embodiment of the present invention, the inorganic particles may be boehmite. As described above, by selecting boehmite as the inorganic particles, a uniform coating layer can be formed to improve the heat resistance of the separation membrane.

[0072] According to one embodiment of the present invention, the average particle size (D50) of the inorganic particles is not subject to any particular limitation, but can be controlled to approximately 0.1 μm or more and 1 μm or less for the formation of a coating layer (130) of uniform thickness and for appropriate porosity. For example, the average particle size (D50) of the inorganic particles may be approximately 0.1 μm or more and 0.9 μm or less, 0.1 μm or more and 0.8 μm or less, 0.1 μm or more and 0.7 μm or less, 0.2 μm or more and 0.6 μm or less, 0.2 μm or more and 0.5 μm or less, 0.2 μm or more and 0.4 μm or less, or 0.2 μm or more and 0.3 μm or less. Within the above-described average particle size (D50) range, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer can be appropriately maintained, and the coating density and porosity can also be maintained at appropriate values, thereby improving ion conductivity. In addition, the thickness of the coating layer (130) formed at the average particle size (D50) of the above-described range can be stably maintained and uniformity can be improved.

[0073] In this specification, "D50 particle size" refers to the particle size at the 50% point of the cumulative distribution of the number of particles according to particle size. The particle size can be measured using a 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 measure the difference in diffraction patterns according to particle size as the particles pass through a laser beam, thereby calculating the particle size distribution. The D50 particle size can be measured by calculating the particle diameter at the point that is 50% of the cumulative distribution of the number of particles according to particle size in the measuring device.

[0074] According to one embodiment of the present invention, the content of the inorganic particles with respect to 100 parts by weight of the coating layer (130) may be about 90 parts by weight or more and less than 100 parts by weight. For example, the content of the inorganic particles with respect to 100 parts by weight of the coating layer (130) may be about 91 parts by weight or more and 99 parts by weight or less, 92 parts by weight or more and 98 parts by weight or less, 93 parts by weight or more and 97 parts by weight or less, or 93 parts by weight or more and 95 parts by weight or less. By controlling the content of the inorganic particles included in the coating layer (130) within the above-described range, the safety of the battery can be ensured by improving the heat resistance of the separator.

[0075] According to one embodiment of the present invention, the first acrylic polymer binder may be in an amount of about 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer. For example, the first acrylic polymer binder may be in an amount of about 1 part by weight or more and 9 parts by weight or less, 1 part by weight or more and 8 parts by weight or less, 1 part by weight or more and 7 parts by weight or less, 1 part by weight or more and 6 parts by weight or less, 1 part by weight or more and 5 parts by weight or less, 1 part by weight or more and 4 parts by weight or less, or 1 part by weight or more and 3 parts by weight or less, per 100 parts by weight of the coating layer. By controlling the content of the first acrylic polymer binder within the above-described range, the binding strength with inorganic particles and the binding strength between the separator and the electrode can be improved, thereby improving battery performance.

[0076] According to one embodiment of the present invention, the first acrylic polymer binder may be an acrylic binder. For example, the acrylic binder may be a polymer comprising a carboxylic acid ester as a repeating unit, and according to one embodiment, may be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0077] According to one embodiment of the present invention, the (meth)acrylic acid ester is (meth)acrylate methyl, (meth)acrylate ethyl, (meth)acrylate n-propyl, (meth)acrylate i-propyl, (meth)acrylate n-butyl, (meth)acrylate i-butyl, (meth)acrylate n-amyl, (meth)acrylate i-amyl, (meth)acrylate hexyl, (meth)acrylate cyclohexyl, (meth)acrylate 2-ethylhexyl, (meth)acrylate n-octyl, (meth)acrylate nonyl, (meth)acrylate decyl, (meth)acrylate hydroxymethyl, (meth)acrylate hydroxyethyl, (meth)acrylate ethylene glycol, di(meth)acrylate ethylene glycol, di(meth)acrylate propylene glycol. Examples include tri(meth)acrylate trimethylolpropane, tetra(meth)acrylate pentaerythritol, hexa(meth)acrylate dipentaerythritol, (meth)acrylate allyl, di(meth)acrylate ethylene, etc., and may be one or more selected from these. Among these, it may be one or more selected from (meth)acrylate methyl, (meth)acrylate ethyl, and (meth)acrylate 2-ethylhexyl, or it may be (meth)acrylate methyl.

[0078] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be of the polyacrylate type. For example, the binder may be one or more selected from styrene-butyl acrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate-based polymers, and more specifically, may be a copolymer containing acrylate.

[0079] According to one embodiment of the present invention, the average particle size (D50) of the first acrylic polymer binder is not subject to any particular limitation, but may be in the range of about 0.1 μm to 1 μm for forming a coating layer (130) of uniform thickness and appropriate porosity. For example, the average particle size (D50) of the first acrylic polymer binder may be about 0.1 μm to 0.8 μm, 0.1 μm to 0.6 μm, 0.1 μm to 0.4 μm, or 0.1 μm to 0.2 μm. By controlling the average particle size (D50) of the first acrylic polymer binder within the above-described range, dispersibility in the slurry prepared for manufacturing the coating layer (130) can be improved, and the thickness of the coating layer (130) formed can be reduced.

[0080] According to one embodiment of the present invention, the hybrid polymer binder may be in an amount of about 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer (130). For example, the hybrid polymer binder may be in an amount of about 1 part by weight or more and 9 parts by weight or less, 1 part by weight or more and 8 parts by weight or less, 1 part by weight or more and 7 parts by weight or less, 1 part by weight or more and 6 parts by weight or less, 1 part by weight or more and 5 parts by weight or less, 1 part by weight or more and 4 parts by weight or less, or 1 part by weight or more and 3 parts by weight or less, per 100 parts by weight of the coating layer (130). By controlling the content of the hybrid polymer binder within the above-described range, the rate of change in resistance can be lowered while maintaining adhesion even after electrolyte impregnation.

[0081] According to one embodiment of the present invention, the hybrid polymer binder may include a fluorine copolymer and an acrylic copolymer. For example, the hybrid polymer binder may be a water-based binder including a fluorine copolymer and an acrylic copolymer. As described above, by including a fluorine copolymer and an acrylic copolymer, the hybrid polymer binder can suppress swelling after electrolyte impregnation, thereby suppressing the increase in resistance of the separator (100).

[0082] According to one embodiment of the present invention, the fluorinated copolymer may be a copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP). For example, the copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP) can improve the flexibility and processability of HFP while maintaining the strength and chemical resistance of PVDF. Furthermore, the copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP) can be made more flexible because, even though the PVDF has various crystalline forms, when HFP is included in the copolymer, the regular chain arrangement of PVDF is disrupted due to the irregular structure of HFP, thereby reducing crystallinity and increasing amorphousness. As described above, chemical resistance and flexibility can be controlled by selecting the copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP) as the fluorinated copolymer.

[0083] According to one embodiment of the present invention, the content of the hexafluoropropylene (HFP) may be about 5% by weight or more and 20% by weight or less with respect to 100% by weight of the fluorinated copolymer. If the above-described range is exceeded, excessive swelling may occur in the electrolyte, and the rate of change in resistance may be inferior.

[0084] One embodiment of the present invention includes an adhesive layer (150) comprising a second acrylic polymer binder on the coating layer (130). By including the adhesive layer (150) comprising a second acrylic polymer binder on the coating layer (130) as described above, adhesive strength can be maintained even after electrolyte impregnation.

[0085] According to one embodiment of the present invention, the second acrylic polymer binder may be in an amount of about 80 parts by weight or more and 95 parts by weight or less per 100 parts by weight of the adhesive layer (150). For example, the second acrylic polymer binder may be in an amount of about 82 parts by weight or more and 95 parts by weight or less, 84 parts by weight or more and 95 parts by weight or less, 85 parts by weight or more and 95 parts by weight or less, 86 parts by weight or more and 94 parts by weight or less, 87 parts by weight or more and 93 parts by weight or less, 88 parts by weight or more and 92 parts by weight or less, or 89 parts by weight or more and 91 parts by weight or less, per 100 parts by weight of the adhesive layer (150). By controlling the content of the second acrylic polymer binder within the above-described range, adhesive strength can be maintained even after electrolyte impregnation.

[0086] In one embodiment of the present invention, the adhesive layer (150) forms a pattern on the coating layer (130). As described above, by forming a pattern on the coating layer (130), the adhesive layer (150) can maintain an adhesive strength of at least a certain level while minimizing the rate of change in resistance.

[0087] According to one embodiment of the present invention, the adhesive layer (150) forming the pattern may be distributed with a coverage of approximately 0% or more and 30% or less of the surface area of ​​the coating layer (130). For example, the coverage of the adhesive layer (150) forming the pattern may be approximately 5% or more and 30% or less, 10% or more and 30% or less, or 15% or more and 30% or less. With coverage within the above-described range, the adhesive strength can be improved and the rate of change in resistance can be reduced, thereby improving battery performance.

[0088] According to one embodiment of the present invention, the thickness of the adhesive layer (150) may be about 0.2 μm or more and 1 μm or less. For example, the thickness of the adhesive layer may be about 0.2 μm or more and 0.9 μm or less, 0.2 μm or more and 0.8 μm or less, 0.2 μm or more and 0.7 μm or less, 0.2 μm or more and 0.6 μm or less, 0.3 μm or more and 0.6 μm or less, and 0.4 μm or more and 0.5 μm or less. At thicknesses within the above-described ranges, the adhesive strength can be improved, and the rate of change in resistance can be reduced to improve battery performance.

[0089] According to one embodiment of the present invention, the resistance change rate of the separator (100) may be about 20% or less. For example, the resistance change rate of the separator (100) may be about 1% or more and 20% or less, 1% or more and 19% or less, 1% or more and 18% or less, 5% or more and 18% or less, or 10% or more and 18% or less. Battery performance can be improved by adjusting the resistance change rate within the above-described range.

[0090] According to one embodiment of the present invention, the wet adhesion strength of the separator (100) may be approximately 8 gf / 20mm or more and 20 gf / 20mm or less. For example, the wet adhesion strength of the separator may be approximately 8 gf / 20mm or more and 16 gf / 20mm or less. With a wet adhesion strength within the above range, battery performance can be improved, and at the same time, the resistance value can be maintained at an appropriate level.

[0091] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention comprises the steps of: providing a porous polymer substrate (110); preparing a slurry for a coating layer comprising a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles; forming a coating layer (130) by applying and drying the slurry for a coating layer comprising the first acrylic polymer binder, the hybrid polymer binder, and inorganic particles onto at least one surface of the porous polymer substrate (110); preparing a slurry for an adhesive layer comprising a second acrylic polymer binder; and forming an adhesive layer (150) by applying and drying the slurry for an adhesive layer comprising the second acrylic polymer binder onto the coating layer (130). More detailed information regarding the process of each step is described in more detail in the description of the examples below. Meanwhile, the above steps are not fixed in a specific order and may be appropriately reversed as needed. For example, the step of preparing the slurry for the coating layer may be performed before the step of preparing the porous polymer substrate (110), or the step of preparing the slurry for the adhesive layer may be performed before the step of preparing the slurry for the coating layer.

[0092] According to one embodiment of the present invention, the solid content of the slurry for the adhesive layer may be about 1% or more and 10% or less. For example, the solid content of the slurry for the adhesive layer may be about 1% or more and 9% or less, 1% or more and 8% or less, 1% or more and 7% or less, 1% or more and 6% or less, 1% or more and 5% or less, 1% or more and 4% or less, or 2% or more and 4% or less. At the solid content of the above-described range, the coverage of the adhesive layer (150) is appropriately maintained so that the increase in resistance can be suppressed and the adhesive strength can be improved.

[0093] As an electrochemical device according to one embodiment of the present invention, the cylindrical lithium secondary battery comprises a positive electrode; a negative electrode; and a separator for the electrochemical device described above, positioned between the positive electrode and the negative electrode. The cylindrical lithium secondary battery can be manufactured by inserting an electrode assembly comprising a positive electrode, a negative electrode, and a separator into a battery case and sealing it. Before sealing the battery case, an electrolyte may be injected to impregnate the electrode assembly with the electrolyte. In this embodiment, a cylindrical lithium secondary battery is exemplified as the electrochemical device, but the present invention is not limited thereto and may be other types of secondary batteries; for example, the electrochemical device may be a cylindrical, prismatic, coin-type, or pouch-type lithium secondary battery. 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.

[0094] As an electrochemical device according to one embodiment of the present invention, the cylindrical lithium secondary battery includes a hybrid polymer binder in the coating layer of the separator and controls the coverage of the adhesive layer so that adhesion strength and resistance can be improved even after electrolyte impregnation.

[0095] In one embodiment of the present invention, the electrochemical element 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. In this specification, the secondary battery is capable of charging and discharging and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples include a non-aqueous electrolyte secondary battery containing a liquid electrolyte, an all-solid-state battery containing a solid electrolyte, a lithium polymer battery containing a gel polymer electrolyte, and a lithium metal battery using lithium metal as a negative electrode, but are not limited thereto.

[0096] According to one embodiment of the present invention, the positive electrode comprises 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 LiMn1-xM xIt may include 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; and one or more of Fe2(MoO4)3.

[0097] According to one embodiment of the present invention, the cathode comprises 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 comprises, as the cathode active material, carbon such as lithium metal oxide, non-graphitizable carbon, or graphite-based carbon; LixFe2O3 (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 포함할 수 있다.

[0098] According to one embodiment of the present invention, the conductive material may be, for example, any one selected from 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. For example, the conductive material may be one selected from 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.

[0099] 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. can be used as the current collector.

[0100] 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-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, 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.

[0101] 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).

[0102] 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 a combination 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.

[0103] According to one embodiment of the present invention, 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 may be provided. Specific examples of the device include, but are not limited to, a power tool that moves by receiving power from an electric 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.

[0104] Hereinafter, the present invention will be described in detail with reference to examples. 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.

[0105]

[0106] Manufacturing of porous polymer substrates

[0107] A polyethylene resin (weight-average molecular weight 1.5 million) was extruded, and a porous polymer substrate (total thickness about 9 μm) was prepared by a wet method.

[0108] Formation of a coating layer

[0109] Boehmite powder (Nabaltec, Act200SM) with a D50 particle size of 300 nm was prepared as an inorganic particle, and a hybrid polymer binder (LBG4330LX, Arkema, D50: 300 nm, a copolymer of PVDF and HFP polymerized in a molar ratio of 95:5 and a copolymer of ethyl acrylate and methyl methacrylate (Tg 20 ℃) ​​mixed in a weight ratio of 7:3), a first acrylic polymer binder (CSB-130, Toyochem, D50: 150 nm, Tg -30 ℃), a PAA-based dispersant (CK-702, Dow Chemical), and a silicone-based surfactant (BYK-348, BYK) were prepared.

[0110] The above-prepared inorganic particles, hybrid polymer binder, first acrylic polymer binder, dispersant, and surfactant were added to water in a weight ratio of 94:2:2:1.4:0.6 and dispersed to prepare a water-based coating layer slurry (solid content: 35%).

[0111] The above-mentioned water-based coating layer slurry was applied to both sides of the above-mentioned porous polymer substrate by a bar coating method using a doctor blade, and dried with a heat gun at 50°C to form a coating layer with a thickness of 1.5 μm on each side.

[0112] Formation of an adhesive layer

[0113] A second acrylic polymer binder (BM2510M, Kuraray) and a silicone surfactant (BYK-348, BYK) were added to water in a weight ratio of 90:10 and dispersed to prepare a water-based adhesive layer slurry (solid content: 2%).

[0114] The water-based adhesive layer slurry was applied to both sides of the above-manufactured coating layer using a doctor blade in a bar coating manner, and dried with a heat gun at 50°C to form an adhesive layer with a thickness of 0.5 μm on each side. At this time, the coverage of the adhesive layer was 15%.

[0115]

[0116] <Example 2>

[0117] In the above Example 1, a separator was prepared in the same manner as in Example 1, except that the solid content of the slurry for the adhesive layer was 4% and the coverage of the adhesive layer was 30%.

[0118]

[0119] <Example 3>

[0120] In Example 2 above, a separator was prepared in the same manner as in Example 1, except that the PVDF and HFP in the PVDF-HFP copolymer included in the hybrid polymer binder had a molar ratio of 85:15 (LP22804, LG Chem).

[0121]

[0122] <Example 4>

[0123] In Example 2 above, a separator was prepared in the same manner as in Example 1, except that the PVDF and HFP in the PVDF-HFP copolymer included in the hybrid polymer binder had a molar ratio of 80:20 (LP228011, LG Chem).

[0124]

[0125] <Comparative Example 1>

[0126] In the above Example 1, a separator was prepared in the same manner as in Example 1, except that the solid content of the slurry for the adhesive layer was 5% and the coverage of the adhesive layer was 50%.

[0127]

[0128] <Comparative Example 2>

[0129] Manufacturing of porous polymer substrates

[0130] A polyethylene resin (weight-average molecular weight 1.5 million) was extruded, and a porous polymer substrate (total thickness about 9 μm) was prepared by a wet method.

[0131] Formation of a coating layer

[0132] Boehmite powder (Nabaltec, Act200SM) with a D50 particle size of 300 nm was prepared as an inorganic particle, and a PVDF (Polyvinylidene Fluoride) polymer binder (solef21510, Solvay), a CTFE (Chlorotrifluoroethylene) polymer binder (solef32008, Solvay), and a PAA-based dispersant (CYR-301, Mitsubishi Chem) were prepared. In the case of Comparative Example 2, the difference from other examples / comparative examples is that the hybrid polymer binder is a PVDF+CFFE combination rather than a PVDF+HFP combination.

[0133] The above-prepared inorganic particles, PVDF polymer binder, CTFE polymer binder, and PAA-based dispersant were added to acetone in a weight ratio of 81:12:5:2 and dispersed to prepare an oil-based coating layer slurry (solid content: 18%).

[0134] A coating layer with a thickness of 1.5 μm was formed on each side of the porous polymer substrate by dip coating with the oil-based coating layer slurry and drying.

[0135] Formation of an adhesive layer

[0136] A second acrylic polymer binder (BM2510M, Zeon) and a silicone surfactant (BYK-348, BYK) were added to water in a weight ratio of 90:10 and dispersed to prepare a water-based adhesive layer slurry (solid content: 4%).

[0137] The water-based adhesive layer slurry was applied to both sides of the above-manufactured coating layer using a doctor blade in a bar coating manner, and dried with a heat gun at 50°C to form an adhesive layer with a thickness of 0.5 μm on each side. At this time, the coverage of the adhesive layer was 30%.

[0138]

[0139] <Comparative Example 3>

[0140] In the above Example 2, a separation membrane was prepared in the same manner as in Example 2, except that a hybrid polymer binder was not used and an acrylamide-based binder (SBS-04, Kureha) was used in a weight ratio of 2.

[0141]

[0142] <Comparative Example 4>

[0143] In the above Example 1, a separator was prepared in the same manner as in Example 1, except that the solid content of the slurry for the adhesive layer was 4% and the binder used in the adhesive layer was a copolymer binder (LBG4330LX, Arkema, D50: 300 nm, a copolymer of PVDF and HFP polymerized in a molar ratio of 95:5 and a copolymer of ethyl acrylate and methyl methacrylate (Tg 20 °C) mixed in a weight ratio of 7:3).

[0144]

[0145] Manufacture of Electrochemical Devices

[0146] Electrochemical devices were each manufactured using the separator membranes for electrochemical devices of the above examples and comparative examples.

[0147] 1) Manufacture of the anode

[0148] Cathode active material (LiNi 0.8 Mn 0.1 Co 0.1 O2), a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chem), and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for an anode active material layer with a concentration of 50 wt% of the components excluding water. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture an anode having an anode active material layer (thickness 120 μm).

[0149] 2) Preparation of the cathode

[0150] Graphite (a blend of natural graphite and artificial graphite), a conductive material (carbon black), a dispersant (Polyvinylpyrrolidone, Junsei, Japan), and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a negative electrode active material layer with a concentration of 50 wt% of the components excluding water. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to manufacture a negative electrode having a negative electrode active material layer (thickness 120 μm).

[0151]

[0152] <Experimental Example>

[0153] Membrane Coverage Analysis

[0154] The surfaces of the separator membranes of Examples 1 and 2 and Comparative Example 1 were measured using a Scanning Electron Microscope (SEM) and are shown in FIGS. 2 to 4.

[0155] Using an image analysis tool, the percentage of the coverage area of ​​the adhesive layer was analyzed based on the difference in composition between the inorganic material and the binder, and is shown in Table 1 below.

[0156] In the surface images measured by SEM, dark shaded areas indicate the adhesive layer and light shaded areas indicate the coating layer. The coverage of the adhesive layer for Examples 1 and 2 shown in FIGS. 2 and 3 was 15% and 30%, respectively, and the coverage of the adhesive layer for Comparative Example 1 shown in FIG. 4 was 50%.

[0157]

[0158] Membrane air permeability measurement

[0159] The air permeability (air time, gully) of the above examples and comparative examples was measured by the ASTM D726-94 method. The gully used herein is the resistance to air flow and is measured by a gully densometer. The air permeability values ​​described herein are for 100 cc of air under a pressure of 12.2 in H2O, with a membrane 1 in 2 It is expressed as the time (in seconds) taken to pass through the cross-section, i.e., the air permeability time. The above air permeability was measured and is shown in Table 1 below.

[0160]

[0161] Wet adhesion measurement of the separator

[0162] The separator of the above example and comparative example was laminated with the anode and impregnated with 1.0 g of electrolyte (ethylene carbonate:ethyl methyl carbonate = 3:7, volume ratio, LiPF6 1M), and left at room temperature for 24 hours. Afterward, a specimen was prepared by lamination using a hot press. At this time, the pressure was applied at 70°C and 5 kgf for 5 minutes. The size of the specimen was 2 cm x 6 cm.

[0163] Afterwards, the wet adhesion strength was measured by peeling at a 90° angle using a tensile testing machine (UTM equipment) and is shown in Table 1 below.

[0164]

[0165] Measurement of resistance change rate

[0166] The separator of the above example and comparative example was prepared with a diameter of 19 π, and a 2016 coin cell was fabricated by placing the separator and electrolyte. At this time, the electrolyte composition included 1M LiPF6, an ethylene carbonate:ethyl methyl carbonate volume ratio of 3:7, and 2 wt% VC (Vinylene Carbonate) as an additive, and the electrolyte was injected. At this time, the resistance was measured by EIS after 3 hours of wetting.

[0167] Afterwards, the coin cell was stored in an oven at 70°C for 12 hours, and the resistance was re-measured using EIS to calculate the rate of change, which is shown in Table 1 below.

[0168]

[0169] Measurement of initial resistance of an electrochemical device

[0170] For the electrochemical elements of the above examples and comparative examples, the resistance was evaluated by the resistance value confirmed when a current was applied for 10 seconds at a rate of 2.5 C-rate at 50 SOC after charging and discharging three times at 25 ℃ and 0.33 C-rate. The measurement results are shown in Table 1 below.

[0171]

[0172] Measurement of initial capacity and capacity loss rate of electrochemical devices

[0173] For the electrochemical devices of the above examples and comparative examples, 100 charge-discharge cycles were performed, with one cycle consisting of charging to 4.2V at 1C in CC-CV mode at 25°C and discharging to 2.5V at a constant current of 1C. Afterward, the initial capacity and capacity loss rate were measured to evaluate the life characteristics. The measurement results after 500 cycles are shown in Table 1 below.

[0174]

[0175] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Coating Layer Binder Type Acrylic-based + PVDF-HFP Acrylic-based + PVDF-HFP Acrylic-based + PVDF-HFP Acrylic-based + PVDF-HFP Acrylic-based + PVDF-HFPPVDF-CTFE Acrylamide-based Acrylic-based + PVDF-HFPPVDF-HFP HFP content (%) 5 5 1 5 2 0 5 -- 5 Adhesive Layer Binder Acrylic-based Acrylic-based Acrylic-based Acrylic-based Acrylic-based Acrylic-based Acrylic-based + PVDF-HFP Coverage of Adhesive Layer (%) 1 5 3 0 3 0 3 5 0 3 0 3 0 Separator Thickness (㎛) 13.0 13.0 13.0 12.9 13.0 13.0 12.9 13.0 Separator Air Permeability (s / 100cc) 8 18 5 8 6 8 8 9 8 12 0 7 6 8 Wet Adhesion (gf / 20mm) 8 15 16 15 23 15 15 Resistance Change Rate (%) 10 12 15 18 30 27.8 25 28 Initial Battery Capacity (mAh) 40.1 40.1 39.8 39.5 39.1 39.3 39.4 39.2 Initial Battery Resistance (mohm) 1.2 11.2 11.2 5 1.3 0 1.3 0 1.2 6 1.3 11.2 7 5 0 Capacity Loss Rate After Cycling (%) 2.7 2.7 4.3 7.0 7.0 5.0 7.8 6.2

[0176]

[0177] According to Table 1 above, the separator and electrochemical device according to Examples 1 to 4 include a hybrid polymer binder in the coating layer, and by controlling the coverage of the adhesive layer formed in the coating layer, the adhesion strength is maintained, and at the same time, swelling is suppressed when impregnated with an electrolyte, thereby lowering the rate of change in resistance. For example, in the case of Examples 1-4, the rate of change in resistance was at the level of 10%-18%, whereas in the case of Comparative Examples 1-4, the rate of change in resistance was relatively large at 25%-30%.

[0178] Meanwhile, Comparative Example 1 was a case where the coverage of the adhesive layer was 50%, and the wet adhesive strength increased to 23 gf / 20mm, but as this layer itself acted as a resistor, it resulted in an increase in the resistance change rate of about 30%.

[0179] In the case of Comparative Example 2, PVDF-CTFE was used instead of a hybrid polymer binder in the coating layer. It can be seen that due to the low heat distortion temperature of CTFE, when a load is applied at a high temperature, it partially dissolves in the electrolyte, leading to an increase in ion levels in the electrolyte, resulting in a resistance change rate of approximately 27.8%.

[0180] In the case of Comparative Example 3, an acrylamide-based binder was used instead of a copolymer in the coating layer, and it can be seen that the resistance change rate increased to the level of 25% as a result of the higher solubility in the electrolyte and the lowering of the ionic conductivity of the electrolyte.

[0181] Comparative Example 4 is a case where the same binder as the hybrid polymer binder used in the coating layer is used instead of the acrylic polymer in the adhesive layer, and it can be seen that the rate of change in resistance increased to 28% as a result of the higher solubility of PVDF-HFP in the electrolyte compared to the acrylic binder under high-temperature electrolyte.

[0182] Accordingly, a separator for an electrochemical device according to one embodiment of the present invention and an electrochemical device including the same can lower the rate of resistance increase while maintaining adhesion by including a hybrid polymer binder in the coating layer and controlling the coverage of the adhesive layer.

[0183] Although the foregoing has been described with reference to the embodiments of the present disclosure, a person skilled in the art or having ordinary knowledge in the art will understand that various modifications and changes can be made to the various embodiments of the present disclosure without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

[0184] [Explanation of the symbol]

[0185] 100: Separator for electrochemical devices

[0186] 110: Porous polymer substrate

[0187] 130: Coating layer

[0188] 150: Adhesive layer

Claims

porous polymer substrate; A coating layer provided on at least one surface of the above-mentioned porous polymer substrate and comprising a first acrylic polymer binder, a hybrid polymer binder, and inorganic particles; and An adhesive layer comprising a second acrylic polymer binder on the above coating layer; A separator for an electrochemical device, wherein the adhesive layer forms a pattern having a certain coverage on the coating layer. In claim 1, A separator for an electrochemical device, wherein the thickness of the porous polymer substrate is 8 μm or more and 15 μm or less. In claim 1, A separator for an electrochemical device, wherein the thickness of the coating layer is 1 μm or more and 3 μm or less. In claim 1, A separator for an electrochemical device, wherein the first acrylic polymer binder is present in an amount of 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer. In claim 1, A separator for an electrochemical device, wherein the above-mentioned hybrid polymer binder is present in an amount of 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer. In claim 1, The above-mentioned hybrid polymer binder comprises a fluorine copolymer and an acrylic copolymer, and is a separator for an electrochemical device. In claim 6, The above-mentioned fluorine copolymer is a copolymer of polyvinylidene fluoride (PVDF) and hexafluoropropylene (HFP), a separator for an electrochemical device. In claim 7, A separator for an electrochemical device having a content of 5% or more and 20% or less of the hexafluoropropylene (HFP) relative to 100% by weight of the fluorinated copolymer. In claim 1, A separator for an electrochemical device, wherein the second acrylic polymer binder is present in an amount of 80 parts by weight or more and 95 parts by weight or less per 100 parts by weight of the adhesive layer. In claim 1, A separator for an electrochemical device, wherein the adhesive layer forming the pattern on the coating layer is distributed with a coverage of more than 0% and less than or equal to 30% of the surface area of ​​the coating layer. In claim 1, A separator for an electrochemical device, wherein the thickness of the adhesive layer is 0.2 μm or more and 1 μm or less. In claim 1, A separator for an electrochemical device, wherein the resistance change rate of the separator is 20% or less. In claim 1, A separator for an electrochemical device, wherein the wet adhesion of the separator is 8 gf / 20mm or more and 20 gf / 20mm or less. Anode; cathode; and An electrochemical device comprising: a separator for an electrochemical device according to claim 1 located between the anode and the cathode.

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