Separator for electrochemical device, electrochemical device comprising same, and manufacturing method thereof

Abstract

The present invention relates to a separator for an electrochemical device, an electrochemical device comprising same, and a manufacturing method thereof, and specifically relates to: a separator for an electrochemical device, the separator having improved adhesion and reducing resistance due to the coverage of an adhesive layer on a coating layer being adjusted so as to be uniform; an electrochemical device comprising the separator; and a manufacturing method thereof.

Description

Separator for electrochemical devices, electrochemical devices including the same, and manufacturing method thereof

[0001] This invention claims the benefit of the filing dates of Korean Patent Application No. 10-2024-0086714, filed with the Korean Intellectual Property Office on July 2, 2024, and Korean Patent Application No. 10-2025-0088208, filed with the Korean Intellectual Property Office on July 1, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a separator for an electrochemical device, an electrochemical device including the same, and a method for manufacturing the same, and more particularly, to a separator for an electrochemical device capable of improving the adhesive strength of the separator and reducing resistance by uniformly controlling the coverage of an adhesive layer on a coating layer, an electrochemical device including the same, and a method for manufacturing the same.

[0003] Among the components of an electrochemical device, the separator is a polymer substrate with a porous structure located between the anode and cathode, which isolates the anode and cathode, prevents electrical short-circuiting between the two electrodes, and allows electrolytes and ions to pass through.

[0004] Although the separator is not directly involved in the electrochemical reaction, it is a component that has a significant impact on the performance and safety of electrochemical devices.

[0005] The physical properties of separators, such as wettability to electrolytes, porosity, and thermal shrinkage, directly impact the operational stability, lifespan, and output characteristics of electrochemical devices. Accordingly, various technological efforts are being made to improve the functionality of separators.

[0006] In particular, various methods have been attempted to enhance the physical properties of the membrane by adding a coating layer to a porous polymer substrate and adding various substances to the coating layer to change the properties of the coating layer. For example, an inorganic substance may be added to the coating layer to enhance the mechanical strength of the membrane, or an inorganic substance or hydrate may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate. Furthermore, an adhesive layer may be added on the coating layer and various substances may be added to the adhesive layer to improve the properties of the adhesive layer.

[0007] When adhesion between the separator and electrode is possible, high interfacial adhesion can be secured during electrode assembly through processes such as lamination and hot pressing. This structure maintains the stability of the cell structure even after electrolyte injection, contributing to improved mechanical durability and reliability of electrochemical devices.

[0008] Meanwhile, when coating an adhesive layer on a coating layer, uniformly controlling the adhesive layer's coverage is challenging. Because adhesive layer coverage significantly impacts the interfacial adhesion and internal resistance characteristics of electrochemical devices, uneven coverage can pose quality concerns. In particular, excessive or uneven application of the adhesive layer can lead to localized increases in resistance between the electrode and separator, or compromise the stability of the cell structure.

[0009] Accordingly, there was a need for research on uniform coverage control that can improve the adhesive performance of electrochemical devices and minimize internal resistance by precisely controlling the coverage of the adhesive layer.

[0010] The technical problem to be achieved by the present invention is to provide a separator for an electrochemical device, an electrochemical device including the same, and a method for manufacturing the same, which can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of an adhesive layer on a coating layer.

[0011] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

[0012] 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 including inorganic particles; and an adhesive layer including a polymer binder on the coating layer; wherein the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer.

[0013] According to one embodiment of the present invention, the polymer binder may be a water-dispersed binder.

[0014] According to one embodiment of the present invention, the polymer binder may be one selected from the group consisting of a fluorine-based binder, an acrylic-based binder, and a combination thereof.

[0015] According to one embodiment of the present invention, the particle size (D50) of the polymer binder may be 100 nm or more and 300 nm or less.

[0016] According to one embodiment of the present invention, the adhesive layer may include a polymer binder group including a plurality of polymer binders.

[0017] According to one embodiment of the present invention, the polymer binder group may be in a hollow shape.

[0018] According to one embodiment of the present invention, the average outer diameter of the polymer binder group may be 1 ㎛ or more and 10 ㎛ or less.

[0019] According to one embodiment of the present invention, the average inner diameter of the polymer binder group may be 100 nm or more and 3 ㎛ or less.

[0020] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the step of forming an adhesive layer including a polymer binder on a porous polymer substrate having a coating layer formed thereon, wherein the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer.

[0021] According to one embodiment of the present invention, the step of forming the adhesive layer may further include a step of generating microbubbles in a slurry for the adhesive layer; a step of coating the slurry for the adhesive layer on a porous polymer substrate on which the coating layer is formed; and a drying step for removing the microbubbles.

[0022] According to one embodiment of the present invention, the microbubbles may be formed using a nano-microbubble device.

[0023] According to one embodiment of the present invention, the nano-micro bubble device may use a mixture of bubbles having a size of 100 to 300 nm and 1 to 50 μm.

[0024] One embodiment of the present invention provides an electrochemical device including an anode, a cathode, and a separator disposed between the anode and the cathode, wherein the separator is any one of the separators described above.

[0025] A separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of the adhesive layer on the coating layer.

[0026] An electrochemical device according to one embodiment of the present invention can improve the performance of the electrochemical device by uniformly controlling the coverage of the surface of the separator, thereby improving the adhesive strength of the separator and reducing resistance.

[0027] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of the adhesive layer by generating microbubbles when manufacturing a slurry for the adhesive layer.

[0028] Figure 1 is a schematic diagram showing the surface of a membrane of Comparative Example 1 according to one embodiment of the present invention.

[0029] Figure 2 is a schematic diagram showing the surface of a membrane of Comparative Example 2 according to one embodiment of the present invention.

[0030] Figure 3 is a schematic diagram showing the surface of a membrane according to Example 1 according to one embodiment of the present invention.

[0031] Figure 4 is a schematic diagram showing the surface of a membrane according to Example 2 of one embodiment of the present invention.

[0032] Figure 5 is a schematic diagram showing the surface of a membrane of Comparative Example 4 according to one embodiment of the present invention.

[0033] Figure 6 is a schematic diagram showing the surface of a membrane according to Example 3 according to one embodiment of the present invention.

[0034] Figure 7 is a schematic diagram showing the surface of a membrane according to Comparative Example 5 according to one embodiment of the present invention.

[0035] Figure 8 is a schematic diagram showing the surface of a membrane of Comparative Example 3 according to one embodiment of the present invention.

[0036] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0037] In this specification, “A and / or B” means “A and B, or A or B.”

[0038] In this specification, “about,” “approximately,” and “substantially” are used to mean a range of or approximation to a numerical value or degree, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly using the disclosure, which mentions exact or absolute numbers provided to aid understanding of the present invention.

[0039] In this specification, when it is said that a component is “on”, this does not exclude other components being placed therebetween, unless otherwise specifically stated, but rather means that other components may be placed thereon.

[0040] In this specification, the characteristic of having pores means that the object includes a plurality of pores and the pores are interconnected with each other, thereby allowing gaseous and / or liquid fluids to pass from one side of the object to the other side.

[0041] In this specification, the separator has a porous characteristic including a plurality of pores, and acts as a porous ion-conducting barrier that allows ions to pass while blocking electrical contact between the cathode and the anode in an electrochemical device.

[0042] Hereinafter, the present invention will be described in more detail.

[0043] One embodiment of the present invention includes a separator (100) for an electrochemical device, comprising: a porous polymer substrate; a coating layer (130) provided on at least one surface of the porous polymer substrate and including inorganic particles; and an adhesive layer (150) including a polymer binder on the coating layer; wherein the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer.

[0044] A separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of the adhesive layer on the coating layer.

[0045] According to one embodiment of the present invention, the separator for an electrochemical device comprises a porous polymer substrate. As described above, the separator for an electrochemical device comprises a porous polymer substrate, thereby allowing lithium ions to pass through while blocking electrical contact, and implementing a shutdown function at an appropriate temperature.

[0046] According to one embodiment of the present invention, the porous polymer substrate may be manufactured using a polyolefin-based resin as a base resin. Examples of the polyolefin-based resin include polyethylene, polypropylene, and polypentene, and the porous polymer substrate may include one or more of these. A porous membrane, i.e., a membrane having a large number of pores, manufactured using such a polyolefin-based resin as a base resin can provide a shutdown function at an appropriate temperature.

[0047] According to one embodiment of the present invention, the weight average molecular weight of the polyolefin resin may be 500,000 or more and 1,500,000 or less. 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 different types of polyolefin resins are mixed and used or the separator is formed 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 weight (Mw) according to the content ratio of each polyolefin resin.

[0048] In this specification, the weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies), and the measurement conditions can be set as follows.

[0049] - Column: PL Olexis (Polymer Laboratories)

[0050] - Solvent: TCB (Trichlorobenzene)

[0051] - Flow rate: 1.0 ml / min

[0052] - Sample concentration: 1.0 mg / ml

[0053] - Injection volume: 200 ㎕

[0054] - Column temperature: 160 ℃

[0055] - Detector: Agilent High Temperature RI detector

[0056] - Standard: Polystyrene (corrected with a cubic function)

[0057] According to one embodiment of the present invention, the porous polymer substrate may be manufactured by a method (wet method) in which a polyolefin resin is mixed with a plasticizer at a high temperature to form a single phase, the polymer material and the plasticizer are phase-separated during a cooling process, the plasticizer is extracted to form pores, and then stretching and heat-setting are performed. In addition, the porous polymer substrate using the polyolefin resin may have a core portion made of a mixture of polyethylene and polypropylene and a polyethylene skin portion laminated on both sides of the core portion.

[0058] 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 can be easily manufactured by a person skilled in the art to conform to the scope of the present invention by controlling the mixing ratio of the plasticizer, the stretching ratio, and the heat-setting treatment temperature.

[0059] According to one embodiment of the present invention, the thickness of the porous polymer substrate may be 1 ㎛ or more and 50 ㎛ or less. Specifically, the thickness of the porous polymer substrate may be 2 ㎛ or more and 45 ㎛ or less, 3 ㎛ or more and 40 ㎛ or less, 4 ㎛ or more and 35 ㎛ or less, 5 ㎛ or more and 30 ㎛ or less, 6 ㎛ or more and 25 ㎛ or less, 7 ㎛ or more and 20 ㎛ or less, or 8 ㎛ or more and 15 ㎛ or less. By controlling the thickness of the porous polymer substrate within the above-described range, the energy density of the battery can be improved.

[0060] According to one embodiment of the present invention, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less. Specifically, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less, 20% by volume or more and 80% by volume or less, 30% by volume or more and 70% by volume or less, or 40% by volume or more and 60% by volume or less. By controlling the porosity of the porous polymer substrate within the above-described range, the permeability of lithium ions through the separator can be controlled.

[0061] According to one embodiment of the present invention, the coating layer (130) is provided on at least one surface of the porous polymer substrate. As described above, by including the coating layer provided on at least one surface of the porous polymer substrate, the separator for an electrochemical device can improve the heat resistance of the separator, improve the mechanical properties, and prevent the separator from shrinking at high temperatures and causing an electrical short circuit in the electrode.

[0062] According to one embodiment of the present invention, the coating layer (130) includes inorganic particles. As described above, by including the inorganic particles in the coating layer, the heat resistance of the separator is improved, the mechanical properties are improved, the separator shrinks at high temperatures, preventing an electrical short circuit of the electrode, and pores can be formed within the coating layer.

[0063] According to one embodiment of the present invention, the inorganic particles that can be used in the coating layer (130) are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are those that can be used in the operating voltage range of the applied electrochemical device (e.g., Li / Li). + There are no particular limitations as long as no oxidation and / or reduction reaction occurs at a voltage of 0 V to 5 V (as a reference).

[0064] According to one embodiment of the present invention, non-limiting examples of the inorganic particles include 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)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), boehmite, etc., and may include one or more of these.

[0065] According to one embodiment of the present invention, the particle size (D50) of the inorganic particles is not particularly limited, but is preferably in the range of 0.1 ㎛ to 1 ㎛ in order to form a coating layer of uniform thickness and an appropriate porosity. Specifically, the particle size (D50) of the inorganic particles may be 0.2 ㎛ to 0.9 ㎛, 0.3 ㎛ to 0.8 ㎛, 0.4 ㎛ to 0.7 ㎛, or 0.5 ㎛ to 0.6 ㎛. Specifically, when it is less than 0.1 ㎛, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer may be reduced, and when it exceeds 1 ㎛, the thickness of the formed coating layer may increase.

[0066] In this specification, "D50 particle size" means the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. The particle size can be measured using a laser diffraction method. Specifically, after the powder to be measured is dispersed in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern according to the particle size is measured to calculate the particle size distribution. By calculating the particle diameter at the point where it becomes 50% of the cumulative distribution of particle numbers according to particle size in the measuring device, the D50 particle size can be measured.

[0067] According to one embodiment of the present invention, the content of the inorganic particles may be 95 parts by weight or more and less than 100 parts by weight with respect to 100 parts by weight of the coating layer. Specifically, the content of the inorganic particles may be 95 parts by weight or more and 99 parts by weight or less or 96 parts by weight or more and 98 parts by weight or less with respect to 100 parts by weight of the coating layer. By controlling the content of the inorganic particles included in the coating layer within the above-described range, the heat resistance of the separator can be improved, thereby ensuring the safety of the battery.

[0068] According to one embodiment of the present invention, the coating layer (130) may include a plurality of pores. Specifically, the coating layer may be a porous coating layer. More specifically, the coating layer may be a porous coating layer including a plurality of pores therein. As described above, by including a plurality of pores, the coating layer can physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0069] According to one embodiment of the present invention, the coating layer (130) may further include a first polymer binder. The coating layer may be formed by inorganic particles being bound by the first polymer binder and accumulated within the side. The pores within the coating layer may be derived from interstitial volume, which is an empty space between the inorganic particles.

[0070] According to one embodiment of the present invention, the first polymer binder may be an acrylic binder, a polyvinylidene binder, or a combination thereof. The combination of the acrylic binder and the polyvinylidene binder may be a mixture of the acrylic binder and the polyvinylidene binder, a copolymer including the acrylic repeating unit and the polyvinylidene repeating unit, or a hybrid of the acrylic binder and the polyvinylidene binder. By selecting the first polymer binder from the above, the porosity of the separation membrane can be maintained.

[0071] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and may preferably be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0072] According to one embodiment of the present invention, the (meth)acrylic acid ester is 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 (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like may be at least one selected from these. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, and methyl (meth)acrylate is particularly preferable.

[0073] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from the group consisting of styrene-butyl acrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0074] According to one embodiment of the present invention, the particle size (D50) of the first polymer binder is not particularly limited, but is preferably in the range of 0.1 ㎛ to 1 ㎛ in order to form a coating layer with a uniform thickness and an appropriate porosity. Specifically, the particle size (D50) of the first polymer binder may be 0.1 ㎛ to 0.8 ㎛, 0.15 ㎛ to 0.6 ㎛, 0.15 ㎛ to 0.4 ㎛, or 0.2 ㎛ to 0.3 ㎛. By controlling the particle size (D50) of the first polymer binder within the above-described range, the dispersibility in the slurry prepared for manufacturing the coating layer can be improved, and the thickness of the formed coating layer can be reduced.

[0075] According to one embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of 1 wt% or more and 50 wt% or less. Specifically, the hexafluoropropylene (HFP) content in the polyvinylidene-based binder may be 1 wt% or more and 50 wt% or less, 2 wt% or more and 45 wt% or less, 3 wt% or more and 40 wt% or less, 4 wt% or more and 35 wt% or less, 5 wt% or more and 30 wt% or less, 7 wt% or more and 25 wt% or less, or 10 wt% or more and 20 wt% or less. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene-based binder having a hexafluoropropylene content of 1 wt% or more and 50 wt% or less, the porosity of the separator can be maintained, and the adhesive strength can be maintained even when the coating layer is wetted by the electrolyte after battery activation. In the present specification, the degree of substitution of the polyvinylidene-based binder may mean the weight ratio containing hexafluoropropylene.

[0076] According to one embodiment of the present invention, the content of the first polymer binder may be 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the coating layer. Specifically, the content of the first polymer binder may be 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 with respect to 100 parts by weight of the coating layer (130). By controlling the content of the first polymer binder particles within the above-described range, the ease of assembly can be improved in the process of assembling the electrode.

[0077] According to one embodiment of the present invention, the thickness of the coating layer (130) on either side of the porous polymer substrate may be 2.5 ㎛ or less. Specifically, the thickness of the coating layer may be greater than 0 ㎛ and less than or equal to 2.5 ㎛, greater than or equal to 0.1 ㎛ and less than or equal to 2.4 ㎛, greater than or equal to 0.2 ㎛ and less than or equal to 2.3 ㎛, greater than or equal to 0.3 ㎛ and less than or equal to 2.2 ㎛, greater than or equal to 0.4 ㎛ and less than or equal to 2.1 ㎛, greater than or equal to 0.5 ㎛ and less than or equal to 2.0 ㎛, greater than or equal to 0.6 ㎛ and less than or equal to 1.9 ㎛, greater than or equal to 0.7 ㎛ and less than or equal to 1.8 ㎛, greater than or equal to 0.8 ㎛ and less than or equal to 1.7 ㎛, or greater than or equal to 0.9 ㎛ and less than or equal to 1.6 ㎛. By controlling the thickness of the coating layer within the above-described range, the heat resistance of the separator can be improved, and the energy density of the separator can be increased.

[0078] In one embodiment of the present invention, the thickness of the porous polymer substrate and / or the coating layer, etc., can be measured using a contact-type thickness measuring device. The contact-type thickness measuring device can be, for example, VL-50S-B from Mitutoyo.

[0079] According to one embodiment of the present invention, the separator (100) for an electrochemical device includes an adhesive layer (150) provided on the coating layer (130). As described above, since the separator for an electrochemical device includes an adhesive layer provided on the coating layer, the adhesion between the electrode and the separator can be secured during the lamination process of the separator and the electrode.

[0080] According to one embodiment of the present invention, the adhesive layer includes a polymer binder. As described above, by including the polymer binder, the adhesive layer can improve adhesive strength with the electrode and enhance bonding properties within the adhesive layer.

[0081] According to one embodiment of the present invention, the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer. Specifically, the coverage of the adhesive layer may be 15% or more and 85% or less, 15% or more and 80% or less, 15% or more and 75% or less, or 20% or more and 70% or less. By controlling the coverage of the adhesive layer within the above-described range, uniformity of coverage can be secured while improving adhesive strength and reducing resistance.

[0082] According to one embodiment of the present invention, the polymer binder may be a water-dispersible binder. Specifically, the polymer binder refers to a binder in the form of an emulsion or suspension in which a water-insoluble polymer compound is dispersed in water, and is a binder capable of having a size distribution of suspended droplets. As described above, by selecting the polymer binder as a water-dispersible binder, the coverage of the adhesive layer can be easily controlled.

[0083] According to one embodiment of the present invention, the polymer binder may be in particle form. As described above, by selecting the polymer binder in particle form, the coverage of the adhesive layer can be easily controlled.

[0084] According to one embodiment of the present invention, the polymer binder can be used without limitation as long as it is an emulsion or suspension of a polymer compound dispersed in water. As a specific example, one or two or more selected from among latex or emulsions or suspensions of polymer compounds such as polystyrene-based, styrene-butadiene-based rubber (SBR), nitrile-based rubber (NBR), polyolefin-based, acrylic-based, acetate-based, polyvinylidene fluoride-based (PVDF) or PVDF-based copolymers, ethylene-vinyl acetate-based (EVA), polyvinyl butyral-based (PVB), polytetrafluoroethylene-based (PTFE), polyimide-based, polyethylene oxide-based, carboxymethyl cellulose-based, polyvinyl alcohol-based, and starch-based polymers or copolymers may be used.

[0085] According to one embodiment of the present invention, the polymer binder may be one selected from the group consisting of a fluorine-based binder, an acrylic binder, and a combination thereof. As described above, by selecting the polymer binder as one selected from the group consisting of a fluorine-based binder, an acrylic binder, and a combination thereof, the coverage of the adhesive layer can be easily controlled.

[0086] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and may preferably be a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0087] According to one embodiment of the present invention, the (meth)acrylic acid ester is 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 (meth)acrylate, di(meth)acrylate, propylene glycol (meth)acrylate, Examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, allyl (meth)acrylate, and ethylene di(meth)acrylate, and the like may be at least one selected from these. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate is preferable, and methyl (meth)acrylate is particularly preferable.

[0088] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be a polyacrylate. For example, the binder may be at least one selected from the group consisting of styrene-butyl acrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, may be a copolymer including acrylate.

[0089] According to one embodiment of the present invention, the fluorine-based binder may be a polyvinylidene-based binder. Specifically, the polyvinylidene-based binder may be a polyvinylidene-based binder having a hexafluoropropylene (HFP) content of 1 wt% or more and 50 wt% or less. Specifically, the hexafluoropropylene (HFP) content in the polyvinylidene-based binder may be 1 wt% or more and 50 wt% or less, 2 wt% or more and 45 wt% or less, 3 wt% or more and 40 wt% or less, 4 wt% or more and 35 wt% or less, 5 wt% or more and 30 wt% or less, 7 wt% or more and 25 wt% or less, or 10 wt% or more and 20 wt% or less. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene-based binder having a hexafluoropropylene content of 1 wt% or more and 50 wt% or less, the porosity of the separator can be maintained, and the adhesive strength can be maintained even when the coating layer is wetted by the electrolyte after battery activation. In the present specification, the degree of substitution of the polyvinylidene-based binder may mean the weight ratio containing hexafluoropropylene.

[0090] According to one embodiment of the present invention, the polymer binder may be an acrylic binder, and preferably an acrylic emulsion binder.

[0091] According to one embodiment of the present invention, the particle size (D50) of the polymer binder may be 100 nm or more and 300 nm or less. Specifically, the particle size (D50) of the polymer binder may be 150 nm or more and 300 nm or less, 200 nm or more and 300 nm or less, or 250 nm or more and 300 nm or less. By controlling the particle size (D50) of the polymer binder within the above-described range, the uniform coverage of the adhesive layer can be controlled.

[0092] According to one embodiment of the present invention, the adhesive layer (150) may include a polymer binder group including a plurality of polymer binders. Specifically, the polymer binder group may be formed in multiple units. As described above, the adhesive layer may easily control the coverage of the adhesive layer by including a polymer binder group including a plurality of polymer binders.

[0093] According to one embodiment of the present invention, the polymer binder group may be hollow. As described above, by selecting the polymer binder group to be hollow, compared to selecting dot-shaped particles with raised centers, the hollow center particle shape can resolve the imbalance in coverage of the adhesive layer.

[0094] According to one embodiment of the present invention, the average outer diameter of the polymer binder group may be 1 ㎛ or more and 10 ㎛ or less. Specifically, the average outer diameter of the polymer binder group may be 1 ㎛ or more and 8 ㎛ or less, 1 ㎛ or more and 6 ㎛ or less, 1 ㎛ or more and 5 ㎛ or less, 1 ㎛ or more and 4 ㎛ or less, 1 ㎛ or more and 3 ㎛ or less, or 1.5 ㎛ or more and 3 ㎛ or less. More specifically, the average outer diameter of the polymer binder group may be about 1.5 ㎛ and 3.0 ㎛ depending on the microbubble size. By controlling the average outer diameter of the polymer binder group within the above-described range, the coverage of the adhesive layer can be controlled and further, coverage imbalance can be resolved.

[0095] According to one embodiment of the present invention, the average inner diameter of the polymer binder group may be 100 nm or more and 3 μm or less. Specifically, the average inner diameter of the polymer binder group may be 100 nm or more and 2 μm or less, 200 nm or more and 2 μm or less, or 300 nm or more and 2 μm or less. More specifically, the average inner diameter of the polymer binder group may be about 300 nm and 2 μm depending on the microbubble size. By controlling the average inner diameter of the polymer binder group within the above-described range, the coverage of the adhesive layer can be controlled and further, coverage imbalance can be resolved.

[0096] One embodiment of the present invention includes a method for manufacturing a separator (100) for an electrochemical device, including a step of forming an adhesive layer (150) including a polymer binder on a porous polymer substrate on which a coating layer (130) is formed, wherein the adhesive layer (150) is distributed with a coverage corresponding to more than 0% and less than 90% of the surface area of ​​the coating layer (130).

[0097] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of the adhesive layer by generating microbubbles during the preparation of the slurry for the adhesive layer. In the method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention, any content that overlaps with the description of the separator for an electrochemical device will be omitted.

[0098] According to one embodiment of the present invention, the method for manufacturing a separator for an electrochemical device may include a step of applying a slurry containing inorganic particles to at least one surface of a porous polymer substrate. As described above, by including the step of applying a slurry containing inorganic particles to at least one surface of the porous polymer substrate, a coating layer can be formed, and the content of inorganic particles in the slurry for the coating layer is excessive, thereby improving the heat resistance of the separator and facilitating evaporation of a solvent.

[0099] According to one embodiment of the present invention, the method for manufacturing a separator for an electrochemical device includes a step of forming an adhesive layer containing a polymer binder on a porous polymer substrate having a coating layer formed thereon. As described above, by including a step of forming an adhesive layer containing a polymer binder on the porous polymer substrate having the coating layer formed thereon, the adhesive layer can be formed to realize adhesive strength between an electrode and a separator.

[0100] According to one embodiment of the present invention, the step of forming the adhesive layer may further include a step of generating microbubbles in the slurry for the adhesive layer; a step of coating the slurry for the adhesive layer on the porous polymer substrate on which the coating layer is formed; and a drying step for removing the microbubbles. Specifically, by including the step of generating microbubbles in the slurry for the adhesive layer, the coverage of the adhesive layer can be easily controlled. In addition, by including the drying step for removing the microbubbles, the coverage of the adhesive layer can be easily controlled by removing the bubbles.

[0101] According to one embodiment of the present invention, the microbubbles may be formed using a nano-microbubble device. As described above, by forming the microbubbles using a nano-microbubble device, the coverage of the adhesive layer can be easily controlled.

[0102] When controlling coverage using a conventional dot-shaped pattern coating method, the center of the dot shape may be raised depending on the coating method, and in this case, there may be limitations in controlling uniform coverage of the adhesive layer.

[0103] In contrast, when using the nano-micro bubble device according to the present invention, a hollow polymer binder group can be formed, and by implementing a centrally empty shape, coverage imbalance can be resolved compared to the dot type.

[0104] According to one embodiment of the present invention, the nano-micro bubble device may use a mixture of bubbles having a size of 100 to 300 nm and 1 to 50 μm. As described above, the nano-micro bubble device can easily control the coverage of the adhesive layer by using a mixture of bubbles having a size of 100 to 300 nm and 1 to 50 μm, and when only nanometer (nm) sized bubbles are used, the size of the generated microbubbles becomes small, which increases the coverage of the adhesive layer, thereby causing an increase in the resistance of the separator. On the other hand, when only micrometer (μm) sized bubbles are used, the size of the generated microbubbles becomes large, which reduces the coverage of the adhesive layer, thereby decreasing the adhesive force between the separator and the electrode.

[0105] According to one embodiment of the present invention, the nano-micro bubble device may be operated in a swirling mode. Specifically, the swirling mode may refer to a method of generating bubbles by utilizing a swirling flow and shear force generated in the process of rotating a fluid. In the present invention, the swirling mode can control the size and distribution of bubbles by adjusting pressure and flow rate, and in particular, it can be suitable for the process of the present invention that requires uniform bubble formation due to excellent fine dispersion of gas.

[0106] According to one embodiment of the present invention, the nano-micro bubble device may be operated in a rotary manner and may have a pressure of 0.01 MPa or more and 0.10 MPa or less. As described above, by adjusting the pressure of the nano-micro bubble device, the size and distribution of bubbles can be controlled, thereby improving the uniformity of coverage of the adhesive layer.

[0107] According to one embodiment of the present invention, the nano-micro bubble device may be operated in a rotary manner and may have a flow rate of 0.1 L / min or more and 1.0 L / min or less. As described above, by adjusting the flow rate of the nano-micro bubble device, the size and distribution of bubbles can be controlled, thereby improving the uniformity of coverage of the adhesive layer.

[0108] One embodiment of the present invention includes an electrochemical device including an anode, a cathode, and a separator disposed between the anode and the cathode, wherein the separator is the separator described above.

[0109] An electrochemical device according to one embodiment of the present invention can improve the performance of the electrochemical device by uniformly controlling the coverage of the surface of the separator, thereby improving the adhesive strength of the separator and reducing resistance.

[0110] An electrochemical device according to one embodiment of the present invention can improve the performance of a battery by improving the bonding strength within the adhesive layer.

[0111] In one embodiment of the present invention, the electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept encompassing a primary battery and a secondary battery. In the present 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 thereof include, but are not limited to, a non-aqueous electrolyte secondary battery including a liquid electrolyte, an all-solid-state battery including a solid electrolyte, a lithium polymer battery including a gel polymer electrolyte, and a lithium metal battery using lithium metal as an anode.

[0112] According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as lithium manganese 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; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; 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 to 0.3); chemical formula LiMn1-xM xA lithium manganese composite oxide represented by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0113] According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes carbon such as lithium metal oxide, non-graphitizable carbon, and graphite carbon as the negative electrode active material; 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, elements of group 1, 2, and 3 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.

[0114] According to one embodiment of the present invention, the conductive material may be, for example, one selected from the group consisting of graphite, carbon black, carbon fibers or metal fibers, metal powders, conductive whiskers, conductive metal oxides, activated carbon, and polyphenylene derivatives, or a mixture of two or more conductive materials among these. More specifically, the conductive material 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, summer black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more conductive materials among these.

[0115] 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.

[0116] According to one embodiment of the present invention, the binder resin may be a polymer commonly used in electrodes in the art. 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 thereof include, but are not limited to, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0117] According to one embodiment of the present invention, the positive electrode slurry for manufacturing the positive electrode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (ADC-01, LG Chemical).

[0118] According to one embodiment of the present invention, the content of the dispersant included in the positive electrode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant included in the positive electrode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the positive electrode slurry.

[0119] According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei, Japan).

[0120] According to one embodiment of the present invention, the content of the dispersant included in the cathode slurry may be more than 0 part by weight and less than or equal to 0.5 part by weight with respect to 100 parts by weight of the cathode slurry. Specifically, the content of the dispersant included in the cathode slurry may be more than 0.05 part by weight and less than or equal to 0.4 part by weight with respect to 100 parts by weight of the cathode slurry.

[0121] According to one embodiment of the present invention, an electrochemical device prepared as described above can be placed in an appropriate case and an electrolyte solution is injected to manufacture a battery.

[0122] According to one embodiment of the present invention, the electrolyte is A + B - As a salt with the same structure, A + is Li + , Na + , K +B containing an ion composed of an alkali metal cation or a combination thereof; - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as or combinations thereof are dissolved or dissociated in organic solvents such as 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), ethyl methyl carbonate (EMC), gamma butyrolactone (γ-butyrolactone) or mixtures thereof, but are not limited thereto.

[0123] One embodiment of the present invention provides a battery module including a battery including the electrochemical element as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool that is powered by 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) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0124] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0125]

[0126] <Example 1>

[0127] Manufacturing of porous polymer substrates

[0128] Polyethylene resin (weight average molecular weight 900,000) was extruded and a porous polymer substrate (total thickness of approximately 9 ㎛, porosity of 40% by volume) was manufactured using a wet method.

[0129] Coating layer formation

[0130] Al2O3 powder with a D50 particle size of 600 nm was prepared as an inorganic particle. An acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) with a D50 particle size of 200 nm was prepared as the first polymer binder, and sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem Co., Ltd.) was prepared as a dispersant.

[0131] The above-prepared inorganic particles, first polymer binder, and dispersant were added to water at a weight ratio of 97:2:1, and dispersed to prepare a slurry for a coating layer.

[0132] The slurry for the coating layer was coated on both sides of the porous polymer substrate and dried to form a coating layer with a thickness of 1.5 μm.

[0133] Adhesive layer formation and separator manufacturing

[0134] An acrylic emulsion (BM2510, ZEON) with a D50 particle size of 300 nm as a polymer binder and a dispersant (polyacrylic acid dispersant, Lubrizol, CK-7058) were added to water, and a surfactant (BYK, BYK-346) was added. The mixture was stirred at a speed of 800 to 1000 rpm for 10 minutes to prepare a polymer binder mixture (solid content concentration 10 wt%).

[0135] At this time, the weight ratio of the polymer binder: dispersant: surfactant was set to 97.5:1.5:1.

[0136] Afterwards, a slurry for an adhesive layer was prepared by generating microbubbles of 100-300 nm and 1-50 μm in size using a nano-microbubble device of a rotary end type. The nano-microbubble device can control microbubbles using a pressure gauge and a flow meter, and in this example, bubbles were generated at a pressure of 0.05 MPa or more and a flow rate of 0.5 L / min or more.

[0137] The slurry for the adhesive layer was applied to both sides of the above-mentioned manufactured coating layer using a doctor blade by a bar coating method, and dried with a heat gun at 50 °C to remove the generated microbubbles, and an adhesive layer of 1.0 μm thickness was formed on each side, thereby manufacturing a separator of a total thickness of 14 μm.

[0138] At this time, the coverage of the adhesive layer was formed to be 20%.

[0139] Figure 3 is a schematic representation of the surface of the membrane of Example 1.

[0140]

[0141] <Example 2>

[0142] In the above Example 1, a slurry for an adhesive layer was prepared by generating microbubbles of 100 to 300 nm and 1 to 50 μm in size using a nano-microbubble device of a rotary end type. In this Example, a separation membrane was prepared in the same manner as in Example 1, except that bubble generation was controlled to be 0.05 MPa or less and a flow rate of 0.3 to 0.5 L / min, thereby forming a 50% coverage of the adhesive layer.

[0143] Figure 4 is a schematic representation of the surface of the membrane of Example 2.

[0144]

[0145] <Example 3>

[0146] In the above Example 1, a slurry for an adhesive layer was prepared by generating microbubbles of 100 to 300 nm and 1 to 50 μm in size using a nano-microbubble device of a rotary end type. In this Example, a separation membrane was prepared in the same manner as in Example 1, except that bubble generation was controlled to form a coverage of the adhesive layer of 70% by setting the pressure to 0.05 MPa or less and the flow rate to 0.3 / min or less.

[0147] Figure 6 is a schematic representation of the membrane surface of Example 3.

[0148]

[0149] <Comparative Example 1>

[0150] In the above Example 1, a separator was manufactured in the same manner as in the above Example 1, except that the adhesive layer was not included.

[0151] Figure 1 is a schematic representation of the surface of the membrane of Comparative Example 1.

[0152]

[0153] <Comparative Example 2>

[0154] A separation membrane was manufactured in the same manner as in Example 1, except that microbubbles of 1 to 50 μm in size were generated using a nano-microbubble device.

[0155] At this time, the coverage of the adhesive layer was formed to be 10%.

[0156] Figure 2 is a schematic representation of the surface of the membrane of Comparative Example 2.

[0157]

[0158] <Comparative Example 3>

[0159] A separation membrane was manufactured in the same manner as in Example 1, except that microbubbles of 100 to 300 nm in size were generated using a nano-microbubble device.

[0160] At this time, the coverage of the adhesive layer was formed to be 90%.

[0161] Figure 8 is a schematic representation of the membrane surface of Comparative Example 3.

[0162]

[0163] Comparative Example 4

[0164] A separator was manufactured in the same manner as in Example 1, except that the formation of the adhesive layer and the manufacture of the separator were as follows.

[0165] Adhesive layer formation and separator manufacturing

[0166] An acrylic emulsion (BM2510, ZEON) with a D50 particle size of 300 nm as a polymer binder and a dispersant (polyacrylic acid dispersant, Lubrizol, CK-7058) were added to water, and a surfactant (BYK, BYK-346) was added. The mixture was stirred at a speed of 800 to 1000 rpm for 10 minutes to prepare a polymer binder mixture (solid content concentration 10 wt%).

[0167] At this time, the polymer binder: dispersant: surfactant were added in a weight ratio of 97.5:1.5:1 to prepare a slurry for an adhesive layer.

[0168] Dot patterning was performed on the manufactured coating layer using the slurry for the above adhesive layer using an inkjet process.

[0169] The size of the above dots is approximately 300 μm, and a separator was manufactured by forming an adhesive layer in a pattern at equal intervals. At this time, the thickness of the adhesive layer is 1.0 μm each, and the adhesive layer coverage is 50%.

[0170] Figure 5 is a schematic representation of the membrane surface of Comparative Example 4.

[0171]

[0172] Comparative Example 5

[0173] In the above Comparative Example 4, a separator was manufactured in the same manner as in Comparative Example 4, except that the adhesive layer was formed by forming a pattern with dots of approximately 200 μm in equal intervals. At this time, the adhesive layer coverage was 70%.

[0174] Figure 7 is a schematic representation of the membrane surface of Comparative Example 5.

[0175]

[0176] <Experimental Example>

[0177] Air permeability measurement

[0178] The membrane permeability of each example and comparative example was measured using a Gurley-type air permeability meter according to JIS P-8117. The time required for 100 cc of air to pass through a 28.6 mm diameter, 645 ㎟ area was measured, and the results are shown in Table 1 below.

[0179]

[0180] Resistance measurement

[0181] The resistance of the separators of each example and comparative example was measured by the following method. An electrolyte was prepared by dissolving LiPF6 at a concentration of 1 molar in a solvent containing ethylene carbonate, propylene carbonate, and propyl propionate in a ratio (volume ratio) of 25:10:65. After impregnating each separator with the electrolyte, coin cells were manufactured, and the electrical resistance was measured using an EIS (Electrochemical impedance spectroscopy) device, and the results are shown in Table 1 below.

[0182]

[0183] Adhesion measurement

[0184] Artificial graphite, carbon black, carboxymethyl cellulose, and an acrylic copolymer as a binder were mixed in a weight ratio of 96:1:1:2 and dispersed in water to prepare a negative electrode slurry, which was then coated on a copper current collector, dried, and rolled to prepare a negative electrode.

[0185] In each example and comparative example, the porous coating layer of the separator obtained was laminated so that the cathode and the separator faced each other, and then sandwiched between two sheets of 100 ㎛ thick polyethylene terephthalate (PET) films, and then pressurized for 1 second under the conditions of 60 ℃ and 1,000 Kgf to laminate the cathode and the separator. The obtained result was fixed to an adhesive strength measuring device, LLOYD Instrument, LF plus, and the upper separator test piece was peeled at a 180° angle at a speed of 300 mm / min at 25 ℃, and the strength at this time was measured, and the results are shown in Table 1 below.

[0186]

[0187] Comparative Example 1Comparative Example 2Example 1Example 2Example 3Comparative Example 3Comparative Example 4Comparative Example 5Coverage (%)010205070905070Coverage control method-Micro bubble nano-Micro bubble nano-Micro bubble nano-Micro bubble nano Bubble dot size 300 μmDot size 200 μmAir permeability (100s / cc)90100103136142155170190Resistance (Ω)0.510.550.60.70.91.21.41.5Adhesion (gf / 25mm)0102145607010090

[0188]

[0189] Figures 1 to 8 schematically illustrate the surfaces of membranes of examples and comparative examples according to one embodiment of the present invention.

[0190] According to the above drawing 1 and table 1, it can be seen that Comparative Example 1 does not include an adhesive layer on the separator, so no polymer binder group exists and the adhesive strength is 0.

[0191] According to the above Fig. 2 and Table 1, Comparative Example 2 uses a nano-micro bubble device to generate micro-sized bubbles (1-50 μm), and thus the coverage of the adhesive layer is very low, so that the polymer binder group is distributed less and the adhesive strength is very low.

[0192] According to the above drawings 3, 4, 6 and Table 1, Examples 1 to 3 used a nano-micro bubble device to generate mixed bubbles of micro-size (1 - 50 μm) and nano-size (100 - 300 nm) and uniformly controlled the coverage of the adhesive layer so that a large number of polymer binder groups were distributed, thereby improving the adhesive strength while reducing the resistance.

[0193] Additionally, according to FIG. 4, it can be seen that the outer diameters of the polymer binder group are about 1.5 μm and 3.0 μm, and the inner diameters of the polymer binder group are about 300 nm and 2 μm.

[0194] According to the above Fig. 8 and Table 1, Comparative Example 3 used a nano-micro bubble device to generate bubbles of nano size (100 - 300 nm), and thus the coverage of the adhesive layer was very high, and it was found that the polymer binder was distributed indiscriminately on the coating layer, and accordingly, the adhesive strength was improved, but the air permeability and resistance were increased.

[0195] According to the above Figure 5 and Table 1, Comparative Example 4 adjusted the coverage by setting the dot size to about 300 μm, but there is a limit to forming uniform coverage compared to the hollow polymer binder group of the present invention, and accordingly, it can be seen that the air permeability and resistance are greatly increased compared to Example 2, which has the same coverage.

[0196] According to the above Figure 7 and Table 1, Comparative Example 5 adjusted the coverage by setting the dot size to about 200 μm, but there is a limit to forming uniform coverage compared to the hollow polymer binder group of the present invention, and accordingly, it can be seen that the air permeability and resistance are greatly increased compared to Example 3, which has the same coverage.

[0197] Therefore, the separator for an electrochemical device according to one embodiment of the present invention can improve the adhesive strength of the separator and reduce resistance by uniformly controlling the coverage of the adhesive layer on the coating layer using a nano-micro bubble device.

[0198] [Explanation of symbols]

[0199] 100: Separator for electrochemical devices

[0200] 130: Coating layer

[0201] 150: Adhesive layer

Claims

1. Porous polymer substrate; A coating layer provided on at least one surface of the porous polymer substrate and including inorganic particles; and An adhesive layer including a polymer binder on the coating layer; A separator for an electrochemical device, wherein the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer.

2. In claim 1, A separator for an electrochemical device, wherein the polymer binder is a water-dispersible binder.

3. In claim 2, A separator for an electrochemical device, wherein the polymer binder is one selected from the group consisting of a fluorine-based binder, an acrylic-based binder, and a combination thereof.

4. In claim 1, A separator for an electrochemical device, wherein the particle size (D50) of the polymer binder is 100 nm or more and 300 nm or less.

5. In claim 1, A separator for an electrochemical device, wherein the adhesive layer comprises a polymer binder group including a plurality of polymer binders.

6. In claim 5, A separator for an electrochemical device, wherein the above polymer binder group is hollow.

7. In claim 6, A separator for an electrochemical device, wherein the average outer diameter of the above polymer binder group is 1 ㎛ or more and 10 ㎛ or less.

8. In claim 6, A separator for an electrochemical device, wherein the average inner diameter of the above polymer binder group is 100 nm or more and 3 ㎛ or less.

9. A step of forming an adhesive layer including a polymer binder on a porous polymer substrate on which a coating layer is formed, A method for manufacturing a separator for an electrochemical device, wherein the adhesive layer is distributed with a coverage corresponding to more than 10% and less than 90% of the surface area of ​​the coating layer.

10. In claim 9, The step of forming the above adhesive layer is: A step of generating microbubbles in a slurry for an adhesive layer; A step of coating the slurry for the adhesive layer on the porous polymer substrate on which the coating layer is formed; and A method for manufacturing a separator for an electrochemical device, further comprising a drying step for removing the above microbubbles.

11. In claim 10, A method for manufacturing a separator for an electrochemical device, wherein the above microbubbles are formed using a nano-microbubble device.

12. In claim 11, A method for manufacturing a separation membrane for an electrochemical device, wherein the above nano-micro bubble device uses a mixture of bubbles having sizes of 100 to 300 nm and 1 to 50 μm.

13. An electrochemical device comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is the separator of claim 1.

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