Separator for electrochemical device, manufacturing method therefor, and electrochemical device comprising separator

Abstract

The present invention relates to a separator for an electrochemical device, a manufacturing method therefor, and an electrochemical device comprising the separator and, particularly, to a separator for an electrochemical device, a manufacturing method therefor, and an electrochemical device comprising the separator, in which different binders are used in a coating layer of the separator to form a pattern, and thus the separator reduces a deviation between a positive electrode adhesive strength and a negative electrode adhesive strength, and improves wettability, and can reduce resistance.

Description

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

[0001] This invention claims the benefit of the filing dates of Korean Patent Application No. 10-2023-0148006, filed with the Korean Intellectual Property Office on October 31, 2023, and Korean Patent Application No. 10-2024-0148548, filed with the Korean Intellectual Property Office on October 28, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a separator for an electrochemical device, a method for manufacturing the same, and an electrochemical device including the separator, and more particularly, to a separator for an electrochemical device capable of reducing the difference between anode and cathode adhesion, improving wettability, and reducing resistance by utilizing and patterning different binders in a coating layer, a method for manufacturing the same, and an electrochemical device including the separator.

[0003] Among the components of electrochemical devices, the separator comprises a porous polymer substrate located between the anode and cathode. It isolates the anode and cathode, prevents electrical short-circuiting between the two electrodes, and allows the passage of electrolytes and ions. While the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability with electrolyte, degree of porosity, and thermal shrinkage, influence the performance and safety of the electrochemical device.

[0004] Accordingly, various methods have been attempted to enhance the physical properties of membranes by adding a coating layer to a porous polymer substrate and by adding various substances to the coating layer to change the properties of the coating layer. For example, inorganic substances may be added to the coating layer to enhance the mechanical strength of the membrane, or inorganic substances or hydrates may be added to the coating layer to enhance the flame retardancy and heat resistance of the polymer substrate.

[0005] The separator can be bonded to the electrode through a lamination process, and a polymer binder can be added to the composition for forming the coating layer of the separator to secure adhesion between the electrode and the separator.

[0006] Meanwhile, depending on the components of the polymer binder, the adhesive strength with the electrode may vary, and there is a problem that folding of the electrochemical device occurs due to the asymmetry of the adhesive strength between the positive and negative electrodes.

[0007] Furthermore, if the adhesive strength between both the positive and negative electrodes is strong using a conventional polymer binder, wettability with respect to the electrolyte may decrease, which may increase the resistance of the electrochemical device.

[0008] Accordingly, there was a need for research on a technology that could minimize the asymmetry of the adhesion between the positive and negative electrodes while maintaining a certain level of adhesion between the positive and negative electrodes.

[0009] The technical problem to be achieved by the present invention is to provide a separator for an electrochemical device, a method for manufacturing the same, and an electrochemical device including the separator, which utilizes and patterns a binder having different adhesive strengths between the positive and negative electrodes in a coating layer to prevent the phenomenon of separator folding due to asymmetry in adhesive strength between the positive and negative electrodes and to reduce resistance due to reduced wettability.

[0010] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011] One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer substrate and including a first polymer binder, a second polymer binder, and inorganic particles, wherein a first surface portion including the first polymer binder and a second surface portion including the second polymer binder are alternately arranged on a surface of the coating layer.

[0012] According to one embodiment of the present invention, the first polymer binder may be a fluorine-based polymer binder.

[0013] According to one embodiment of the present invention, the second polymer binder may be a hybrid polymer of a fluorine-based polymer binder and an acrylic-based polymer binder.

[0014] According to one embodiment of the present invention, the area of ​​the second surface portion may be 40% or less based on the total surface area of ​​the coating layer.

[0015] According to one embodiment of the present invention, the anodic adhesive strength of the first surface portion may be greater than the anodic adhesive strength of the second surface portion.

[0016] According to one embodiment of the present invention, the negative adhesive strength of the second surface portion may be greater than the negative adhesive strength of the first surface portion.

[0017] According to one embodiment of the present invention, the average thickness of the coating layer may be 0.5 μm or more and 1.0 μm or less.

[0018] According to one embodiment of the present invention, the content of the first polymer binder may be 10 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.

[0019] According to one embodiment of the present invention, the content of the second polymer binder may be 10 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.

[0020] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the steps of: forming a coating layer by alternately applying a first slurry containing a first polymer binder and a second slurry containing a second polymer binder to at least one surface of a porous polymer substrate; wherein the coating layer has a first surface portion containing the first polymer binder and a second surface portion containing the second polymer binder alternately arranged on the surface.

[0021] According to one embodiment of the present invention, the step of providing the coating layer may be performed using gravure coating, spray coating, slot die coating, bar coating or roll coating.

[0022] According to one embodiment of the present invention, the loading amount of the first slurry for the coating layer is 7 g / m 2 Exceeding 10 g / m 2 It could be as follows:

[0023] According to one embodiment of the present invention, the loading amount of the second slurry for the coating layer is 4 g / m 2 More than 7 g / m 2 It could be as follows:

[0024] One embodiment of the present invention provides an electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode, and any one of the above-described membranes.

[0025] According to one embodiment of the present invention, a separator for an electrochemical device utilizes and patterns binders having different adhesive strengths between the positive and negative electrodes in the coating layer, thereby maintaining the adhesive strength between the positive and negative electrodes while suppressing an increase in resistance due to a decrease in wettability.

[0026] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can suppress an increase in resistance due to a decrease in wettability while maintaining the adhesive strength between the positive and negative electrodes by forming a coating layer of a constant thickness and a constant pattern by controlling the loading amount during coating.

[0027] Figure 1 is a schematic diagram showing a separation membrane according to one embodiment of the present invention.

[0028] Figure 2 is an image showing the surface of the coating layer of Example 1 of the present invention.

[0029] Figure 3 is an image showing the surface of the coating layer of Example 2 of the present invention.

[0030] Figure 4 is an image showing the surface of the coating layer of Comparative Example 1 of the present invention.

[0031] Figure 5 is an image showing the surface of the coating layer of Comparative Example 2 of the present invention.

[0032] Figure 6 is an image showing the surface of the coating layer of Comparative Example 3 of the present invention.

[0033] Figure 7 is an image showing the surface of the coating layer of Comparative Example 4 of the present invention.

[0034] Figures 8a to 8f sequentially show the wettability states of Examples 1 and 2 of the present invention and Comparative Examples 1 to 4.

[0035] 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.

[0036] In this specification, “A and / or B” means “A and B, or A or B.”

[0037] 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.

[0038] In this specification, the characteristic of “having pores” means that the object includes a plurality of pores and that 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.

[0039] 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.

[0040] Hereinafter, an embodiment of the present invention will be described in detail 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.

[0041] Hereinafter, the present invention will be described in more detail.

[0042] One embodiment of the present invention includes a porous polymer substrate (110); and a coating layer (130) provided on at least one surface of the porous polymer substrate and including a first polymer binder, a second polymer binder, and inorganic particles, wherein a first surface portion (131) including the first polymer binder and a second surface portion (133) including the second polymer binder are alternately arranged on the surface of the coating layer, including a separator (100) for an electrochemical device.

[0043] According to one embodiment of the present invention, a separator for an electrochemical device utilizes and patterns binders having different adhesive strengths between the positive and negative electrodes in the coating layer, thereby maintaining the adhesive strength between the positive and negative electrodes while suppressing an increase in resistance due to a decrease in wettability.

[0044] A separator for an electrochemical device according to one embodiment of the present invention can improve the cohesion between inorganic particles and a polymer binder, thereby improving the adhesion between a polymer substrate and a coating layer.

[0045] FIG. 1 is a schematic diagram of a separator (100) for an electrochemical device according to one embodiment of the present invention. Referring to FIG. 1, the separator (100) for an electrochemical device according to one embodiment of the present invention will be described in detail.

[0046] 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 the polyolefin-based resin include polyethylene, polypropylene, polypentene, etc., and the porous polymer substrate may include one or more of these. A porous separation membrane manufactured using such a polyolefin-based resin as a base resin, i.e., having a large number of pores, 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 weights according to the content ratio of each polyolefin resin.

[0048] In the present invention, 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 (110) may be manufactured by a method (wet method) of mixing a polyolefin resin with a plasticizer (diluent) at a high temperature to form a single phase, separating the polymer material and the plasticizer during a cooling process, extracting the plasticizer to form pores, and then performing stretching and heat-setting.

[0058] According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the separation membrane (100) can be easily manufactured by a person skilled in the art by controlling the mixing ratio of the plasticizer, the stretching ratio, the heat-setting treatment temperature, etc. to conform to the scope of the present invention.

[0059] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) may be 1 ㎛ or more and 30 ㎛ or less. Specifically, the thickness of the porous polymer substrate (110) may be 2 ㎛ or more and 28 ㎛ or less, 3 ㎛ or more and 26 ㎛ or less, 4 ㎛ or more and 24 ㎛ or less, 5 ㎛ or more and 22 ㎛ or less, 6 ㎛ or more and 20 ㎛ or less, 7 ㎛ or more and 18 ㎛ or less, 8 ㎛ or more and 16 ㎛ or less, 9 ㎛ or more and 14 ㎛ or less, or 9 ㎛ or more and 12 ㎛ or less. By controlling the thickness of the porous polymer substrate within the above-described range, the volume of the electrochemical device can be minimized, and the positive electrode and the negative electrode can be electrically insulated.

[0060] According to one embodiment of the present invention, the electrochemical device separator (100) includes a coating layer (130) provided on at least one surface of the porous polymer substrate (110). Specifically, the electrochemical device separator (100) includes a coating layer (130) provided on one or both surfaces of the porous polymer substrate (110). As described above, since the electrochemical device separator (100) includes the coating layer (130) provided on at least one surface of the porous polymer substrate (110), the heat resistance of the separator can be improved, the mechanical properties can be improved, and the shrinkage of the separator at high temperatures can be prevented, thereby preventing an electrical short circuit of the electrode.

[0061] According to one embodiment of the present invention, the coating layer (130) includes a first polymer binder, a second polymer binder, and inorganic particles. As described above, the coating layer (130) includes the first polymer binder, the second polymer binder, and the inorganic particles, thereby improving the heat resistance of the separator, improving the mechanical properties, preventing the separator from shrinking at high temperatures and causing an electrical short circuit of the electrode, and forming pores within the coating layer.

[0062] According to one embodiment of the present invention, a coating layer may be formed using a composition for forming a coating layer comprising the inorganic particles and the polymer binder mixture. By using a composition for forming a coating layer comprising the inorganic particles and the polymer binder mixture as described above, the convenience of the work for forming a coating layer can be improved, and the viscosity of the composition for forming a coating layer can be easily controlled.

[0063] According to one embodiment of the present invention, the composition for forming a coating layer may further include a solvent. As described above, by the composition for forming a coating layer further including a solvent, the convenience of the operation for forming a coating layer can be improved, and the inorganic particles and the polymer binder mixture can be uniformly dispersed within the composition for forming a coating layer. In the present specification, the solvent may refer to a dispersion medium, and an emulsion in which the inorganic particles and the polymer binder mixture are dispersed by the solvent may refer to the composition for forming a coating layer.

[0064] According to one embodiment of the present invention, the solvent may be one selected from the group consisting of water, acetone, ethanol, isopropyl alcohol (IPA), dimethylacetamide (DMAc), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), acetonitrile, and combinations thereof. Specifically, the solvent is preferably water. By selecting the solvent from the above, the viscosity of the composition for forming the coating layer can be controlled, and the dispersibility of the inorganic particles and the polymer binder within the solvent can be improved.

[0065] According to one embodiment of the present invention, the composition for forming the coating layer may further include an additive. As described above, by further including an additive in the composition for the inorganic coating layer, the binding force of the inorganic particles can be improved, and the dispersibility of the composition for the inorganic coating layer can be improved.

[0066] According to one embodiment of the present invention, the additive may include a dispersant, a surfactant, an antifoaming agent, a flame retardant, an adhesion promoter, etc. By selecting the additive from the above, the dispersibility and phase stability of the composition for the inorganic coating layer can be improved, bubbles can be removed or flame retardancy can be added, adhesion can be improved, and wettability between the polymer substrate and the composition for forming the coating layer can be improved.

[0067] According to one embodiment of the present invention, the dispersant may include at least one selected from polyacrylic acid, oil-soluble polyamine, oil-soluble amine compound, fatty acid, fatty alcohol, sorbitan fatty acid ester, tannic acid, and pyrogallic acid. Preferably, the dispersant may be sodium carboxymethyl cellulose (CMC-Na). By selecting the dispersant from the above-described ones, the dispersibility and phase stability of the coating layer composition can be improved.

[0068] According to one embodiment of the present invention, the content of the dispersant may be more than 0 part by weight and less than or equal to 5 parts by weight based on 100 parts by weight of the composition for forming the coating layer. Specifically, the content of the dispersant may be more than 0 part by weight and less than or equal to 4 parts by weight, more than or equal to 1 part by weight and less than or equal to 3 parts by weight, or more than or equal to 1 part by weight and less than or equal to 2 parts by weight based on 100 parts by weight of the composition for forming the coating layer. By adjusting the content of the dispersant within the above-described range, the dispersibility and phase stability of the composition for forming the coating layer can be improved.

[0069] According to one embodiment of the present invention, the coating layer (130) includes a plurality of pores. Specifically, the coating layer (130) includes a plurality of micropores. The plurality of pores may be formed by a polymer binder and inorganic particles contained in the polymer binder mixture being densely filled in the coating layer, and may be a plurality of micropores resulting from an interstitial volume formed between the inorganic particles. These micropores have a structure in which they are interconnected, and exhibit a porous structure through which gas or liquid can pass from one side to the other. As described above, since the coating layer (130) includes a plurality of pores, an electrolyte in a battery, which will be described later, is allowed to permeate the separator.

[0070] According to one embodiment of the present invention, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles are not particularly limited as long as they do not undergo oxidation and / or reduction reactions within the operating voltage range of the applied electrochemical device (e.g., 0 to 5 V based on Li / Li+). In particular, when inorganic particles having ion transfer capability are used, the ion conductivity within the electrochemical device can be increased, thereby improving performance. In addition, when inorganic particles having a high dielectric constant are used as inorganic particles, the ion conductivity of the electrolyte can be improved by contributing to an increase in the degree of dissociation of an electrolyte salt, such as a lithium salt, in a liquid electrolyte. The inorganic particles may include high-dielectric constant inorganic particles having a dielectric constant of 5 or more or 10 or more, inorganic particles having a lithium ion transfer capability, or a mixture thereof. Specifically, the inorganic particles may include BaSO4, BaTiO3, Pb(Zr, Ti)O3(PZT), b1-xLaxZr1-yTiyO3(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 (AlO(OH)) and combinations thereof, but this is only an example and is not limited thereto.

[0071] According to one embodiment of the present invention, the average particle diameter (D50) of the inorganic particles (not shown) is not particularly limited, but is preferably in the range of 0.3 ㎛ to 1 ㎛ for forming a coating layer (130) of uniform thickness and having an appropriate porosity. Specifically, when it is less than 0.3 ㎛, 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.

[0072] 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 the cumulative distribution of particle numbers according to particle size in the measuring device becomes 50%, the D50 particle size can be measured.

[0073] According to one embodiment of the present invention, the content of the inorganic particles may be 70 parts by weight or more and 90 parts by weight or less with respect to 100 parts by weight of the composition for a coating layer. Specifically, the content of the inorganic particles may be 75 parts by weight or more and 90 parts by weight or less, 77 parts by weight or more and 89 parts by weight or less, 79 parts by weight or more and 88 parts by weight or less, 80 parts by weight or more and 87 parts by weight or less, 82 parts by weight or more and 86 parts by weight or less, or 84 parts by weight or more and 86 parts by weight or less with respect to 100 parts by weight of the composition for a coating layer. By controlling the content of the inorganic particles within the above-described range, the insulation and heat resistance of the separator can be improved, thereby preventing the separator from shrinking at high temperatures.

[0074] According to one embodiment of the present invention, a first surface portion (131) including the first polymer binder and a second surface portion (133) including the second polymer binder are alternately arranged on the surface of the coating layer (130). As described above, by alternately arranging the first surface portion including the first polymer binder and the second surface portion including the second polymer binder on the surface of the coating layer, it is possible to maintain a constant adhesive force with the electrodes by including portions having different adhesive forces with the positive and negative electrodes, while also improving wettability with the electrolyte.

[0075] According to one embodiment of the present invention, the first polymer binder and the second polymer binder may be a particle-type binder or a soluble binder. Specifically, the particle-type binder has a property of maintaining its original particle shape without being deformed even when dispersed in a solvent, and examples thereof may include polyvinylidene-based or acrylic polymers. The soluble binder may be dissolved in a polar solvent including water, and examples thereof may include polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), or polyacrylamide (PAM). Preferably, the first polymer binder and the second polymer binder may be particle-type binders.

[0076] According to one embodiment of the present invention, the first polymer binder may be a fluorinated polymer binder. As described above, by selecting the first polymer binder as a fluorinated polymer binder, the porosity of the separator can be maintained, and even if the coating layer is wetted by an electrolyte after battery activation, the adhesive strength can be maintained.

[0077] According to one embodiment of the present invention, the second polymer binder may be a hybrid polymer of a fluorine-based polymer binder and an acrylic polymer binder. As described above, by selecting the second polymer binder as a hybrid polymer of a fluorine-based polymer binder and an acrylic polymer binder, wettability by an electrolyte can be improved and the resistance of the battery can be reduced.

[0078] According to one embodiment of the present invention, the fluorine-based polymer binder may be a PVDF-based polymer binder. The PVDF-based polymer is a polymer containing vinylidene fluoride as a polymerization unit. The PVDF-based polymer may include a homopolymer of vinylidene fluoride (i.e., polyvinylidene fluoride), a copolymer of vinylidene fluoride and another polymerizable monomer (comonomer), or a mixture of two or more thereof.

[0079] The above comonomer may be at least one selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorofluoroethylene, 1,2 difluoroethylene, perfluoro(methylvinyl)ether, perfluoro(ethylvinyl)ether, perfluoro(propylvinyl)ether, perfluoro(1,3-dioxole), perfluoro(2,2-dimethyl-1,3-dioxole), trichloroethylene, and vinyl fluoride. Non-limiting examples of the PVDF polymer include polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polyvinylidene fluoride-co-tetrafluoroethylene, polyvinylidene fluoride-co-trifluoroethylene, polyvinylidene fluoride-co-trifluorochloroethylene, and polyvinylidene fluoride-co-ethylene, and one selected from these or a mixture of two or more thereof may be used. Preferably, the PVDF polymer may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP).

[0080] In this specification, the content of comonomer in the vinylidene fluoride polymer resin can be measured by the 1H-NMR method using a Varian 500MHz. For detailed measurement methods, refer to Journal of Materials Chemistry, 2012, 22, 341 or AMT-3412-0k. The NMR spectrum can be confirmed using appropriate equipment, such as a Bruker Avance III HD 700MHz NMR or a Varian 500MHz NMR.

[0081] According to one embodiment of the present invention, the acrylic polymer binder is a polymer containing a carboxylic acid ester as a repeating unit, and may be specifically a (meth)acrylic acid ester. More specifically, 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, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, It may be one selected from the group consisting of tetra(meth)acrylate pentaerythritol, hexa(meth)acrylate dipentaerythritol, allyl (meth)acrylate, ethylene di(meth)acrylate, and combinations thereof. Preferably, the (meth)acrylic acid ester is at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0082] According to one embodiment of the present invention, the second polymer binder may include a PVDF-based polymer binder and an acrylic-based polymer binder. Preferably, the second polymer binder may be polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and an acrylic-based binder, and the weight ratio may be 5:5 to 7:3. Preferably, the weight ratio may be 5:5.

[0083] According to one embodiment of the present invention, the acrylic polymer resin may be a copolymer containing styrene and acrylate in a weight ratio of 5:5 to 7:3. According to one embodiment of the present invention, the acrylate copolymerized with styrene may be butylacrylate.

[0084] According to one embodiment of the present invention, the first polymer binder may be a fluorine-based polymer binder, and may be the same as the fluorine-based polymer included in the second polymer binder.

[0085] According to one embodiment of the present invention, the area of ​​the second surface portion may be 40% or less based on the total surface area of ​​the coating layer. Specifically, the area of ​​the second surface portion may be more than 0 and less than 40%, 5% or more and less than 40%, 10% or more and less than 40%, 15% or more and less than 40%, 20% or more and less than 40%, 22% or more and less than 40%, 24% or more and less than 40%, or 25% or more and less than 40% based on the total surface area of ​​the coating layer. If it is less than the above-described range, the area of ​​the first surface portion may increase, thereby reducing the adhesive strength with the negative electrode, and if it exceeds the above-described range, the adhesive strength of the positive electrode may be reduced. As described above, by controlling the area of ​​the second surface portion based on the total surface area of ​​the coating layer, the adhesive strength of the positive electrode and the negative electrode can be improved, while also improving wettability by the electrolyte.

[0086] According to one embodiment of the present invention, the anode adhesive strength of the first surface portion may be greater than the anode adhesive strength of the second surface portion. Specifically, the first polymer binder included in the first surface portion may have superior anode adhesive strength to the second polymer binder included in the second surface portion. As described above, by adjusting the anode adhesive strength of the first surface portion to be greater than the anode adhesive strength of the second surface portion, a constant adhesive strength with the anode can be secured and the asymmetry of the anode and cathode adhesive strengths can be alleviated.

[0087] According to one embodiment of the present invention, the negative electrode adhesive strength of the second surface portion may be greater than the negative electrode adhesive strength of the first surface portion. Specifically, the second polymer binder included in the second surface portion may have superior negative electrode adhesive strength to the first polymer binder included in the first surface portion. As described above, by adjusting the negative electrode adhesive strength of the second surface portion to be greater than the negative electrode adhesive strength of the first surface portion, a constant adhesive strength with the negative electrode can be secured and the asymmetry of the positive and negative electrode adhesive strengths can be alleviated.

[0088] According to one embodiment of the present invention, the difference in the dry adhesion between the positive and negative electrodes of the coating layer may be 50 gf / 20 mm or less. Specifically, the difference in the dry adhesion between the positive and negative electrodes of the coating layer may be 0 gf / 20 mm or more and 50 gf / 20 mm or less, or 0 gf / 20 mm or more and 32 gf / 20 mm or less. By controlling the difference in the dry adhesion between the positive and negative electrodes of the coating layer within the above-described range, the stability of the battery can be improved.

[0089] According to one embodiment of the present invention, the difference in the wet adhesion between the positive electrode and the negative electrode may be 25 gf / 20 mm or less. Specifically, the difference in the wet adhesion between the positive electrode and the negative electrode may be 0 gf / 20 mm or more and 25 gf / 20 mm or less, or 0 gf / 20 mm or more and 15 gf / 20 mm or less. By controlling the difference in the wet adhesion between the positive electrode and the negative electrode of the coating layer within the above-described range, the stability of the battery can be improved.

[0090] According to one embodiment of the present invention, the average thickness of the coating layer may be 0.5 μm or more and 1.0 μm or less. If the average thickness of the coating layer exceeds the range and becomes thicker, cell resistance may increase. In addition, if the thickness exceeds the above-mentioned range, the area to be bonded after the lamination process increases, and thus wettability by the electrolyte may decrease. If the thickness falls below the above-mentioned range, the area to be bonded after the lamination process narrows, and thus the adhesive strength may decrease.

[0091] In one embodiment of the present invention, the thickness of the 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.

[0092] According to one embodiment of the present invention, the content of the first polymer binder may be 10 parts by weight or more and 15 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 11 parts by weight or more and 14 parts by weight or less with respect to 100 parts by weight of the coating layer. By adjusting the content of the first polymer binder within the above-described range, wettability and adhesive strength can be improved.

[0093] According to one embodiment of the present invention, the content of the second polymer binder may be 10 parts by weight or more and 15 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 11 parts by weight or more and 14 parts by weight or less with respect to 100 parts by weight of the coating layer. By adjusting the content of the first polymer binder within the above-described range, wettability and adhesive strength can be improved.

[0094] One embodiment of the present invention includes a method for manufacturing a separator for an electrochemical device, comprising the steps of: forming a coating layer by alternately applying a first slurry containing a first polymer binder and a second slurry containing a second polymer binder to at least one surface of a porous polymer substrate; wherein the coating layer has a first surface portion containing the first polymer binder and a second surface portion containing the second polymer binder alternately arranged on the surface.

[0095] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can suppress an increase in resistance due to a decrease in wettability while maintaining the adhesive strength between the positive and negative electrodes by forming a coating layer of a constant thickness and a constant pattern by controlling the loading amount during coating.

[0096] A method for manufacturing a separator (100) for an electrochemical device, which is an embodiment of the present invention, is specifically described. Furthermore, in this specification, any overlapping portions with those described in the separator for the electrochemical device will be omitted.

[0097] According to one embodiment of the present invention, the step of providing a coating layer may be performed using gravure coating, spray coating, slot die coating, bar coating, or roll coating. Preferably, the step of providing the coating layer may be performed using gravure coating.

[0098] According to one embodiment of the present invention, the loading amount of the first slurry for the coating layer is 7 g / m 2Exceeding 10 g / m 2 It may be as follows. If it exceeds the above-mentioned range, the area to be bonded after the lamination process increases, and accordingly, wettability by the electrolyte may decrease. If it falls short of the above-mentioned range, the area to be bonded after the lamination process narrows, and accordingly, the adhesive strength may decrease.

[0099] According to one embodiment of the present invention, the loading amount of the second slurry for the coating layer is 4 g / m 2 More than 7 g / m 2 It may be as follows. If it exceeds the above-mentioned range, the area to be bonded after the lamination process increases, and accordingly, wettability by the electrolyte may decrease. If it falls short of the above-mentioned range, the area to be bonded after the lamination process narrows, and accordingly, the adhesive strength may decrease.

[0100] One embodiment of the present invention includes an electrochemical device comprising: an anode; a cathode; and any one of the above separators interposed between the anode and the cathode.

[0101] An electrochemical device according to one embodiment of the present invention can improve wettability for an electrolyte solution and enhance adhesion between an anode and a cathode by including a coating layer that forms a certain pattern using different polymer binders.

[0102] 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-xLithium 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 LiMn 1-x M x A 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.

[0103] 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 negative electrode 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), Si, SiO x (0 <x<2), SiC, Si 합금 등의 실리콘계 재료; 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; 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.

[0104] According to one embodiment of the present invention, the positive electrode current collector and / or the negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the electrochemical device, and specifically, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0105] According to one embodiment of the present invention, the conductive material may be one selected from the group consisting of graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whisker, conductive metal oxide, carbon nanotube, activated carbon, and polyphenylene derivative, or a mixture of two or more conductive materials among these. The carbon nanotube has a graphite sheet having a cylindrical shape with a nano-sized diameter, and sp 2It has a bonding structure, and exhibits the characteristics of a conductor or a semiconductor depending on the angle and structure at which the graphite plane is rolled. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) depending on the number of bonds forming the wall, and these carbon nanotubes can be appropriately selected depending on the use of the dispersion. More specifically, it can 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.

[0106] According to one embodiment of the present invention, the binder resin may be a binder resin 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.

[0107] According to one embodiment of the present invention, an electrode assembly includes an anode, a cathode, and a separator interposed between the anode and the cathode, and an electrochemical device can be manufactured by placing the electrode assembly in a suitable case and injecting an electrolyte.

[0108] 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 + Contains ions composed of alkali metal cations or combinations thereof, such as B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - The salt containing an anion such as or a combination thereof may be dissolved or dissociated in an organic solvent including, but not limited to, 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 a mixture thereof.

[0109] According to one embodiment of the present invention, a battery module including a battery including the electrode assembly as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source are provided. 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.

[0110] 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.

[0111]

[0112] <Example 1>

[0113] 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.

[0114] Al2O3 powder having a D50 particle size of 400 nm was prepared as an inorganic particle. A copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (LBG4430LX, Arkema) was prepared as a first polymer binder, and sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem) was prepared as a dispersant. The prepared inorganic particles, first polymer binder, and dispersant were added to water at a weight ratio of 85:14:1, and then the inorganic particles were crushed and dispersed to prepare a first slurry for a coating layer.

[0115] Al2O3 powder having a D50 particle size of 400 nm was prepared as an inorganic particle. Acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (LBG4430LX, Arkema Co., Ltd.) were prepared as a second polymer binder, and sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GL Chem Co., Ltd.) was prepared as a dispersant. The prepared inorganic particles, the second polymer binder (acrylic emulsion: PVdF-HFP = 5:5), and the dispersant were added to water at a weight ratio of 85:14:1, and then the inorganic particles were crushed and dispersed to prepare a second slurry for a coating layer.

[0116] The first slurry and the second slurry were alternately placed on a porous polymer substrate, and applied using a gravure coating method so that the thickness of the coating layer was 0.5 μm or more and 1.0 μm or less, and then dried to form a coating layer. At this time, the loading amount of the first slurry was 9.5 g / m 2 The loading of the second slurry is 4.5 g / m 2 Thus, the area of ​​the second surface was 25% (Fig. 2).

[0117]

[0118] <Example 2>

[0119] In the above Example 1, the loading amount of the first slurry is 7.5 g / m 2The loading of the second slurry is 6.5 g / m 2 A coating layer was manufactured in the same manner as in Example 1, except that the area of ​​the second surface portion was 40% (Fig. 3).

[0120]

[0121] <Comparative Example 1>

[0122] In the above Example 1, a coating layer that does not form a pattern was manufactured using only the second slurry without using the first slurry (Fig. 4).

[0123]

[0124] Comparative Example 2

[0125] In the above Example 1, the loading amount of the first slurry is 6.5 g / m 2 The loading of the second slurry is 7.5 g / m 2 A coating layer was manufactured in the same manner as in Example 1, except that the area of ​​the second surface portion was 60% (Fig. 5).

[0126]

[0127] <Comparative Example 3>

[0128] In the above Example 1, a coating layer was manufactured in the same manner as in the above Example 1, except that the thickness of the coating layer was adjusted to 1.5 μm (Fig. 6).

[0129]

[0130] <Comparative Example 4>

[0131] In the above Example 1, a coating layer was manufactured in the same manner as in Example 1, except that an acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) was used instead of a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (LBG4430LX, Arkema Co., Ltd.) as the first polymer binder (Fig. 7).

[0132]

[0133] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 First slurry First polymer binder PVDFPVDF-PVDFPVDF Acrylic inorganic Al2O3 Al2O3-Al2O3 Al2O3 Al2O3 Second slurry Second polymer binder PVDF+Acrylic PVDF+Acrylic PVDF+Acrylic PVDF+Acrylic PVDF+Acrylic PVDF+Acrylic inorganic Al2O3 Al2O3 Al2O3 Al2O3 Al2O3 Coating layer thickness (μm) 0.5~1.0 0.5~1.0 0.5~1.0 0.5~1.0 1.5 0.5~1.0 Loading amount (g / m 2 ) 1st slurry 9.57.5-6.57.57.5 2nd slurry 4.56.56.57.56.56.5 2nd surface area (%) 2540-604040

[0134]

[0135] [Measurement of coating layer surface area]

[0136] In order to measure the surface area of ​​the coating layer of Examples 1 and 2 and Comparative Examples 1 to 4, the surface EDAX F-Peak analysis was performed to measure the area.

[0137] According to FIGS. 2 to 7, the surface area of ​​the coating layer of Examples 1 and 2 and Comparative Examples 1 to 4 can be confirmed.

[0138]

[0139] <Manufacturing of electrochemical devices>

[0140] 1) Manufacturing of the anode

[0141] Cathode active material (LiNi) 0.8 Mn 0.1 Co 0.1O2), a conductive agent (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical), 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 cathode active material layer with a concentration of 50 wt% of the remaining components excluding water. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture a cathode having a cathode active material layer (thickness 120 μm).

[0142] 2) Manufacturing of cathode

[0143] Graphite (natural graphite and artificial graphite blend), conductive agent (carbon black), dispersant (polyvinylpyrrolidone, Junsei, Japan), and binder resin (PVDF-HFP and PVDF blend) 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 remaining components excluding water. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to manufacture an anode having an anode active material layer (thickness 120 μm).

[0144]

[0145] <Experimental Example>

[0146] [Dry adhesion measurement]

[0147] The separators of the above examples and comparative examples were cut into 70 mm (length) x 20 mm (width), and the prepared electrodes and separators were laminated using a press under the conditions of 60 ℃, 6.5 MPa, and 1 sec to produce specimens. The prepared specimens were fixed by attaching them to a glass plate using double-sided tape, and at this time, the electrodes were positioned so that they faced the glass plate. The separator portion of the specimen was peeled at an angle of 180° at a speed of 150 mm / min at 25 ℃, and the strengths of each of the positive and negative electrodes at this time were measured and summarized in Table 2 below.

[0148]

[0149] [Wet Adhesion Measurement]

[0150] The separators of the above examples and comparative examples were cut into 70 mm (length) x 20 mm (width), and the prepared electrodes and separators were laminated using a press under the conditions of 60 ℃, 6.5 MPa, and 1 sec to prepare specimens. The prepared specimens were loaded into a battery case together with the electrolyte and maintained for 4 hours to impregnate the specimens with the electrolyte. The electrolyte used was a mixture of ethylene carbonate and ethyl methylate in a volume ratio of 7:3 and prepared at a concentration of LiPF61M. After that, the specimens were taken out of the case and fixed by attaching them to a glass plate using double-sided tape, and at this time, the electrodes were positioned facing the glass plate. The separator portion of the specimen was peeled at a 90° angle at a speed of 200 mm / min at 25 ℃, and the strengths of each of the positive and negative electrodes at this time were measured and summarized in Table 2 below.

[0151]

[0152] [Electrical resistance measurement]

[0153] Resistance was measured by sandwiching each separator between SUS and injecting electrolyte into coin cells, and measuring resistance (ER) using the EIS method. The frequency range was 100,000 to 10,000 Hz.

[0154]

[0155] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Dry Adhesion (gf / 20mm) Positive Adhesion 472757505 Negative Adhesion 152265454555 Wet Adhesion (gf / 20mm) Positive Adhesion 252046405 Negative Adhesion 101530223735 Electrical Resistance (ER, Ω) 0.75 0.72 0.91 0.82 1.20.98

[0156]

[0157] According to Table 2 above, it can be confirmed that in Examples 1 and 2, when the area of ​​the second surface portion is included at 40% or less, both the positive and negative adhesive strengths of the dry adhesive strength and the positive and negative adhesive strengths of the wet adhesive strength are excellent and have low resistance.

[0158] In contrast, Comparative Example 1 has a problem in that it does not form a pattern on the surface of the coating layer and only includes the second polymer, resulting in inferior anode adhesion and increased resistance compared to the example.

[0159] In the above comparative example 2, it can be seen that the anode adhesive strength is poor because the second surface area exceeds 40%, and there is a problem of poor wet adhesive strength and an increase in resistance compared to the example.

[0160] The above comparative example 3 has a problem in that the thickness of the coating layer exceeds 0.5 to 1.0 μm, so the adhesive strength is good, but the electrical resistance increases significantly.

[0161] The above comparative example 4 has a problem in that the first polymer binder is acrylic, and thus becomes film-like when impregnated with electrolyte, thereby increasing electrical resistance.

[0162]

[0163] [Wetness Measurement]

[0164] After the lamination process of the separator of the above examples and comparative examples, the membrane was placed vertically and immersed in an electrolyte solution to measure the extent to which the electrolyte was sucked up by capillary action.

[0165] Figures 8a to 8f sequentially show the wettability states of Examples 1 and 2 of the present invention and Comparative Examples 1 to 4.

[0166] According to the above FIGS. 8a to 8f, FIGS. 8a and 8b are examples, and it can be confirmed that the degree of electrolyte sucked up is greater than that of the comparative examples FIGS. 8c to 8f, so that the wetting is excellent.

[0167]

[0168] [Comparison of positive / negative adhesion by binder]

[0169] Example 1 Positive adhesion (gf / 20mm) Negative adhesion (gf / 20mm) First polymer binder 5512 Second polymer binder 1065

[0170]

[0171] According to Table 3 above, the first polymer binder has superior anodic adhesion compared to the second polymer binder, and thus, when the binders are alternately placed in the coating layer according to the present invention, the anodic adhesion of the first polymer binder can be excellently expressed.

[0172] In addition, the second polymer binder has superior negative electrode adhesiveness compared to the first polymer binder, so that when the binders are alternately arranged in the coating layer according to the present invention, the negative electrode adhesiveness of the second polymer binder can be excellently expressed.

[0173] Accordingly, the separator for an electrochemical device according to one embodiment of the present invention can prevent an increase in resistance by improving wettability while improving dry adhesiveness and wet adhesion by alternately arranging the first surface portion and the second surface portion on the surface of the coating layer, controlling the surface area thereof, and controlling the type of binder.

[0174]

[0175] [Explanation of symbols]

[0176] 100: Membrane

[0177] 110: Porous polymer substrate

[0178] 130: Coating layer

[0179] 131: First surface area

[0180] 133: Second surface area

Claims

1. Porous polymer substrate; and It is provided on at least one side of the porous polymer substrate, and includes a coating layer including a first polymer binder, a second polymer binder, and inorganic particles, A separator for an electrochemical device, wherein a first surface portion including the first polymer binder and a second surface portion including the second polymer binder are alternately arranged on the surface of the coating layer.

2. In claim 1, A separator for an electrochemical device, wherein the first polymer binder is a fluorine-based polymer binder.

3. In claim 1, A separator for an electrochemical device, wherein the second polymer binder is a hybrid polymer of a fluorine-based polymer binder and an acrylic-based polymer binder.

4. In claim 1, A separator for an electrochemical device, wherein the area of ​​the second surface portion is 40% or less based on the total surface area of ​​the coating layer.

5. In claim 1, A separator for an electrochemical device, wherein the anode adhesive strength of the first surface portion is greater than the anode adhesive strength of the second surface portion.

6. In claim 1, A separator for an electrochemical device, wherein the negative adhesive strength of the second surface portion is greater than the negative adhesive strength of the first surface portion.

7. In claim 1, A separator for an electrochemical device, wherein the average thickness of the coating layer is 0.5 μm or more and 1.0 μm or less.

8. In claim 1, A separator for an electrochemical device, wherein the content of the first polymer binder is 10 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.

9. In claim 1, A separator for an electrochemical device, wherein the content of the second polymer binder is 10 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the coating layer.

10. A step of forming a coating layer by alternately applying a first slurry containing a first polymer binder and a second slurry containing a second polymer binder to at least one surface of a porous polymer substrate; A method for manufacturing a separator for an electrochemical device, wherein the coating layer has a first surface portion including the first polymer binder and a second surface portion including the second polymer binder alternately arranged on the surface.

11. In claim 10, A method for manufacturing a separator for an electrochemical device, wherein the step of providing the above coating layer is performed using gravure coating, spray coating, slot die coating, bar coating or roll coating.

12. In claim 10, The loading amount of the first slurry for the above coating layer is 7 g / m 2 Exceeding 10 g / m 2 A method for manufacturing a separator for an electrochemical device, comprising:

13. In claim 10, The loading amount of the second slurry for the above coating layer is 4 g / m 2 More than 7 g / m 2 A method for manufacturing a separator for an electrochemical device, comprising:

14. An electrochemical device comprising: a positive electrode; a negative electrode; and a separator interposed between the positive electrode and the negative electrode, the separator of claim 1.

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