Separator for electrochemical device, electrochemical device including same, and manufacturing method therefor

Abstract

A separator for an electrochemical device of the present invention comprises: a porous polymer substrate; and a coating layer disposed on at least one surface of the porous polymer substrate and including a polymer binder and inorganic particles, wherein the coating layer includes a first coating layer and a second coating layer formed on the first coating layer, and has a packing density of about 1.70 g / cm3 or less.

Description

Separator for an electrochemical device, an electrochemical device including the same, and a method for manufacturing the same

[0001] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0193594 filed on December 23, 2024 and Korean Patent Application No. 10-2025-0199452 filed on December 15, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of the specification.

[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.

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

[0004] As an electrochemical device, a lithium secondary battery consists of four core components: a positive electrode, a negative electrode, a separator, and an electrolyte. These components interact organically to repeatedly charge and discharge, storing and releasing energy. For example, during the charging and discharging process, electricity is generated as lithium ions move through the electrolyte between the positive and negative electrodes, separated by a separator. Generally, the positive and negative electrodes determine the performance of the battery, while the electrolyte and separator determine the safety of the secondary battery.

[0005] The present invention provides a separator for an electrochemical device capable of minimizing the rate of increase in air permeability by controlling the coating layer structure of the separator, an electrochemical device including the same, and a method for manufacturing the same.

[0006] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below.

[0007] One embodiment of the present invention comprises: a porous polymer substrate; and a coating layer provided on at least one surface of the porous polymer substrate and comprising a polymer binder and inorganic particles, wherein the coating layer comprises a first coating layer and a second coating layer formed on the first coating layer, and the packing density of the coating layer is 1.70 g / cm³ 3 The present invention provides a separator for an electrochemical device.

[0008] According to one embodiment of the present invention, the thickness of the porous polymer substrate may be about 8 μm or more and 15 μm or less.

[0009] According to one embodiment of the present invention, the packing density of the first coating layer is about 1.80 g / cm³ 3 It could be an abnormality.

[0010] According to one embodiment of the present invention, the thickness of the first coating layer may be about 0.5 μm or more and 2.5 μm or less, and the thickness of the second coating layer may be about 0.5 μm or more and 2.5 μm or less.

[0011] According to one embodiment of the present invention, the air permeability of the separation membrane may be about 150% or less compared to the air permeability of the porous polymer substrate.

[0012] According to one embodiment of the present invention, the air permeability of the porous polymer substrate may be about 50 s / 100cc or more and 80 s / 100cc or less.

[0013] According to one embodiment of the present invention, the air permeability of the separator may be about 100 s / 100cc or less.

[0014] According to one embodiment of the present invention, the content of the inorganic particles in 100 parts by weight of the coating layer may be about 80 parts by weight or more and 95 parts by weight or less.

[0015] According to one embodiment of the present invention, the content of the polymer binder in 100 parts by weight of the coating layer may be about 1 part by weight or more and 10 parts by weight or less.

[0016] According to one embodiment of the present invention, the first coating layer and the second coating layer may be formed with the same composition in terms of the type and content of the polymer binder and inorganic particles.

[0017] One embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising the steps of: providing a porous polymer substrate; forming a first coating layer by applying a coating layer slurry to at least one surface of the porous polymer substrate and drying it; and forming a second coating layer by applying a coating layer slurry to the first coating layer and drying it, wherein the drying temperature is about 40°C to 80°C.

[0018] According to one embodiment of the present invention, the drying temperature when forming the first coating layer may be lower than the drying temperature when forming the second coating layer.

[0019] According to one embodiment of the present invention, the drying temperature when forming the first coating layer may be about 40°C or higher and 50°C or lower.

[0020] According to one embodiment of the present invention, the drying temperature when forming the second coating layer may be about 60°C or higher and 80°C or lower. 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 aforementioned separators.

[0021] A separator for an electrochemical device according to one embodiment of the present invention can suppress the increase in resistance of the electrochemical device by minimizing the rate of increase in air permeability through controlling the packing density of the coating layer.

[0022] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can minimize the rate of increase in air permeability and suppress the increase in resistance of the electrochemical device by controlling drying conditions after applying a slurry for a coating layer.

[0023] An electrochemical device according to one embodiment of the present invention can suppress the increase in resistance of the electrochemical device by minimizing the rate of increase in air permeability of a separator including a coating layer.

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

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

[0026] FIG. 2 is a schematic diagram showing the coating layer structure of Example 1 according to one embodiment of the present invention.

[0027] FIG. 3 is a schematic diagram showing the coating layer structure of Comparative Example 3 according to one embodiment of the present invention.

[0028] In parts of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art understand that the drawings are intended to illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated compared to others. Additionally, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to hinder the spirit of the various embodiments of the present invention.

[0029] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0030] In this specification, "A and / or B" means "A and B, or A or B".

[0031] In this specification, "about," "approximately," and "substantially" are used to mean a range of numerical or degree or an approximation thereof, taking into account inherent manufacturing and material tolerances (e.g., ±5%), and are used to prevent an infringer from unfairly exploiting the disclosure in which precise or absolute figures provided to aid in understanding the invention are mentioned.

[0032] In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components.

[0033] In this specification, the characteristic of having pores means that a gaseous and / or liquid fluid can pass from one side to the other side of the object through a structure in which the object includes a plurality of pores and said pores are interconnected.

[0034] Among the components of an electrochemical device, the separator is a porous material containing numerous pores that acts as a porous ion-conducting barrier, blocking electrical contact between the cathode and the anode while allowing ions to pass through. For example, the separator may include a polymer substrate with a porous structure and isolates the anode and cathode to prevent electrical short circuits between the two electrodes, while simultaneously allowing the electrolyte and ions to pass through. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, porosity, and thermal shrinkage rate, can affect the performance and safety of the electrochemical device.

[0035] To enhance the physical properties of such separation membranes, various methods are being attempted to improve the properties of the coating layer by adding a coating layer to a porous polymer substrate and adding various materials to the coating layer. For example, inorganic materials may be added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic materials or hydrates may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0036] Within the coating layer, inorganic particles can be connected to other inorganic particles by a polymer binder to form an interstitial volume, and lithium ions can move through the interstitial volume. That is, the coating layer containing a polymer binder and inorganic particles serves to prevent thermal shrinkage of the separator while simultaneously facilitating the movement of lithium ions through the separator.

[0037] Meanwhile, by providing a coating layer containing the above-mentioned inorganic particles, the inorganic particles may act as an obstacle blocking the movement path of lithium ions, thereby increasing the resistance of the secondary battery. The present invention provides a separator capable of minimizing the increase in resistance even when the separator is provided with a coating layer containing inorganic particles to improve battery stability.

[0038] 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.

[0039] FIG. 1 is a schematic diagram of a separator for an electrochemical device according to one embodiment of the present invention.

[0040] The present invention will be described in more detail below.

[0041] One embodiment of the present invention comprises: a porous polymer substrate (110); and a coating layer (130) provided on at least one surface of the porous polymer substrate (110) and comprising a polymer binder and inorganic particles, wherein the coating layer (130) comprises a first coating layer (131) formed on the porous polymer substrate (110) and a second coating layer (133) formed on the first coating layer (131), and the packing density of the coating layer (130) is approximately 1.70 g / cm³ 3 It includes a separator (100) for an electrochemical device, which is less than or equal to the above.

[0042] A separator (100) for an electrochemical device according to one embodiment of the present invention can suppress the increase in resistance of the electrochemical device by minimizing the rate of increase in air permeability by controlling the packing density of the coating layer (130). The rate of increase in air permeability may refer, for example, to the rate at which the air permeability increases relative to the air permeability of the porous polymer substrate (110) when the coating layer (130) is formed on the porous polymer substrate (110).

[0043] The above-described separator (100) for an electrochemical device includes a porous polymer substrate (110). As described above, by including the porous polymer substrate (110) in the separator (100) for an electrochemical device, it is possible to implement a shutdown function, which is a safety function that prevents dangers such as fire or explosion by blocking electrical contact between the positive and negative electrodes of a lithium secondary battery while allowing lithium ions to pass through, and stopping the operation of the battery at an appropriate temperature when the internal temperature of the battery rises abnormally.

[0044] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured using a polyolefin-based resin as a base resin. Examples of polyolefin-based resins include polyethylene, polypropylene, polypentene, etc., and may include one or more of these. A porous separator having, for example, a plurality of pores, manufactured using such a polyolefin-based resin as a base resin can provide a shutdown function at an appropriate temperature.

[0045] According to one embodiment of the present invention, the weight-average molecular weight of the polyolefin resin may be about 500,000 to 2 million. By controlling the weight-average molecular weight of the polyolefin resin within the above-described range, the compression resistance of the separator can be improved. Furthermore, when using a mixture of different types of polyolefin resins or forming a separator with a multilayer structure made of different types of polyolefin resins, the weight-average molecular weight of the polyolefin resin can be calculated by adding the weight-average molecular weights according to the content ratio of each polyolefin resin.

[0046] In the present 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.

[0047] - Column: PL Olexis (Polymer Laboratories)

[0048] - Solvent: TCB (Trichlorobenzene)

[0049] - Flow rate: 1.0 ml / min

[0050] - Sample concentration: 1.0 mg / ml

[0051] - Injection volume: 200 µl

[0052] - Column temperature: 160 ℃

[0053] - Detector: Agilent High Temperature RI detector

[0054] - Standard: Polystyrene (corrected by a cubic function)

[0055] According to one embodiment of the present invention, the porous polymer substrate (110) may be manufactured by a method (wet method) in which a polyolefin-based resin is mixed with a plasticizer (diluent) at a high temperature to form a single phase, the polymer material and the plasticizer are separated during the cooling process, the plasticizer is extracted to form pores, and then stretched and heat-set.

[0056] According to one embodiment of the present invention, the average size of the pores and the maximum size of the pores of the porous polymer substrate (110) can be easily manufactured by a person skilled in the art to meet the scope of the present invention by adjusting the mixing ratio of the plasticizer, the stretching ratio, and the heat-setting treatment temperature.

[0057] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) may be about 8 μm or more and 15 μm or less. For example, the thickness of the porous polymer substrate (110) may be about 8 μm or more and 14 μm or less, 8 μm or more and 13 μm or less, 8 μm or more and 12 μm or less, 8 μm or more and 11 μm or less, or 8 μm or more and 10 μm or less, and according to one embodiment, it may be about 9.1 μm. By controlling the thickness of the porous polymer substrate (110) within the above-described range, the energy density of the battery can be improved.

[0058] According to one embodiment of the present invention, the thickness of the porous polymer substrate (110) can be measured by a contact measurement method using a thickness gauge (Mitutoyo, VL-50S-B).

[0059] According to one embodiment of the present invention, the air permeability of the porous polymer substrate (110) may be about 50 s / 100cc or more and 80 s / 100cc or less. For example, the air permeability of the porous polymer substrate (110) may be about 60 s / 100cc or more and 80 s / 100cc or less, or 65 s / 100cc or more and 75 s / 100cc or less, and according to one embodiment, may be about 70 s / 100cc. By controlling the air permeability of the porous polymer substrate within the above-described range, ion conductivity and durability can be improved, and furthermore, resistance can be improved.

[0060] According to one embodiment of the present invention, the air permeability is measured using a Gurley densometer (Gurley, 4110N) such that 100 cc of air has a diameter of 28.6 mm and an area of ​​645 mm² 2 The time (s) required to pass through the membrane is measured and expressed as the air passage time. The Gurley used here is the resistance to air flow and is measured by a Gurley densometer.

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

[0062] According to one embodiment of the present invention, the coating layer (130) comprises a polymer binder and inorganic particles. As described above, by including the polymer binder and inorganic particles, the coating layer (130) improves the heat resistance of the separator, improves mechanical properties, prevents the separator from shrinking at high temperatures and causing an electrical short circuit in the electrode, and can form pores within the coating layer (130).

[0063] According to one embodiment of the present invention, the coating layer (130) may be formed by inorganic particles being bound by a polymer binder and accumulated within the layer. The pores within the coating layer (130) may originate from the interstitial volume, which is the empty space between the inorganic particles.

[0064] According to one embodiment of the present invention, the coating layer (130) may be a porous coating layer comprising a plurality of pores. As described above, by the coating layer (130) comprising a plurality of pores, it is possible to physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0065] According to one embodiment of the present invention, the inorganic particles usable in the coating layer (130) are not particularly limited as long as they are electrochemically stable. For example, the inorganic particles usable in one embodiment of the present invention are within the operating voltage range of the electrochemical device to which they are applied (e.g., Li / Li). + It is not particularly limited as long as oxidation and / or reduction reactions do not occur at a standard of 0 V to 5 V.

[0066] According to one embodiment of the present invention, examples of the inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 Examples include O3-PbTiO3(PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc-tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), etc., and may include one or more of these.

[0067] According to one embodiment of the present invention, the inorganic particles may be alumina (Al2O3). As described above, the heat resistance of the separator can be improved by selecting alumina (Al2O3) as the inorganic particles. However, since the inorganic particles are included in the coating layer (130), the inorganic particles may become an obstacle that blocks the lithium ion movement pathway, thereby causing an increase in resistance of the battery manufactured using the separator (100); however, as described below, the rate of increase in air permeability can be minimized and furthermore, the increase in resistance can be minimized by adjusting the formation conditions of the coating layer (130).

[0068] According to one embodiment of the present invention, the average particle size (D50) of the inorganic particles is not subject to any particular limitation, but may be in the range of about 0.1 μm or more and 1 μm or less for the formation of a coating layer (130) of uniform thickness and appropriate porosity. For example, the average particle size (D50) of the inorganic particles may be about 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, 0.4 μm or more and 0.7 μm or less, or 0.5 μm or more and 0.6 μm or less. By maintaining the average particle size (D50) in the above-described range, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer (130) can be maintained within an appropriate range, and the thickness of the coating layer (130) formed can also be maintained within an appropriate range, thereby improving the uniformity of the coating layer (130).

[0069] In this specification, "D50 particle size" refers to the particle size at the 50% point of the cumulative distribution of the number of particles according to particle size. The particle size can be measured using a laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to measure the difference in diffraction patterns according to particle size as the particles pass through a laser beam, thereby calculating the particle size distribution. The D50 particle size can be measured by calculating the particle diameter at the point that is 50% of the cumulative distribution of the number of particles according to particle size in the measuring device.

[0070] According to one embodiment of the present invention, the content of the inorganic particles in 100 parts by weight of the coating layer (130) may be about 80 parts by weight or more and 95 parts by weight or less. For example, the content of the inorganic particles with respect to 100 parts by weight of the coating layer (130) may be about 82 parts by weight or more and 93 parts by weight or less, 84 parts by weight or more and 91 parts by weight or less, 85 parts by weight or more and 90 parts by weight or less, or 86 parts by weight or more and 89 parts by weight or less. By controlling the content of the inorganic particles included in the coating layer (130) within the above-described range, the safety of the battery can be ensured by improving the heat resistance of the separator.

[0071] According to one embodiment of the present invention, the polymer binder may be an acrylic binder. Specifically, the acrylic binder may be a polymer comprising a carboxylic acid ester as a repeating unit, preferably 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 (meth)acrylate methyl, (meth)acrylate ethyl, (meth)acrylate n-propyl, (meth)acrylate i-propyl, (meth)acrylate n-butyl, (meth)acrylate i-butyl, (meth)acrylate n-amyl, (meth)acrylate i-amyl, (meth)acrylate hexyl, (meth)acrylate cyclohexyl, (meth)acrylate 2-ethylhexyl, (meth)acrylate n-octyl, (meth)acrylate nonyl, (meth)acrylate decyl, (meth)acrylate hydroxymethyl, (meth)acrylate hydroxyethyl, (meth)acrylate ethylene glycol, di(meth)acrylate ethylene glycol, di(meth)acrylate propylene glycol. Examples include tri(meth)acrylate trimethylolpropane, tetra(meth)acrylate pentaerythritol, hexa(meth)acrylate dipentaerythritol, (meth)acrylate allyl, di(meth)acrylate ethylene, etc., and may be one or more selected from these. According to one embodiment, among these, it may be one or more selected from (meth)acrylate methyl, (meth)acrylate ethyl, and (meth)acrylate 2-ethylhexyl, and for example, may be (meth)acrylate methyl.

[0073] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be of the polyacrylate type. For example, the binder may be one or more selected from styrene-butyl acrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate-based polymers, or may be a copolymer containing acrylate.

[0074] According to one embodiment of the present invention, the average particle size (D50) of the polymer binder is not subject to any particular limitation, but may be approximately 0.1 μm or more and 1 μm or less for the formation of a coating layer (130) of uniform thickness and appropriate porosity. For example, the average particle size (D50) of the polymer binder may be approximately 0.1 μm or more and 0.8 μm or less, 0.1 μm or more and 0.6 μm or less, 0.1 μm or more and 0.4 μm or less, or 0.1 μm or more and 0.2 μm or less. The rate of increase in air permeability can be suppressed within the average particle size (D50) of the above-described range. Furthermore, by controlling the average particle size (D50) of the polymer binder within the above-described range, dispersibility in the slurry prepared for manufacturing the coating layer can be improved, and the rate of increase in air permeability can be minimized.

[0075] According to one embodiment of the present invention, the content of the polymer binder may be about 1 part by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer (130). Specifically, the content of the polymer binder may be 1 part by weight or more and 9 parts by weight or less, 2 parts by weight or more and 8 parts by weight or less, 2 parts by weight or more and 7 parts by weight or less, 3 parts by weight or more and 7 parts by weight or less, 4 parts by weight or more and 7 parts by weight or less, 5 parts by weight or more and 7 parts by weight or less, or 6 parts by weight or more and 7 parts by weight or less, per 100 parts by weight of the coating layer (130). The increase in the rate of air permeability can be suppressed within the binder content of the above-described range. By controlling the content of the polymer binder within the above-described range, the binding strength with inorganic particles and the binding strength between the separator and the electrode can be improved, thereby improving battery performance and minimizing the rate of air permeability increase.

[0076] According to one embodiment of the present invention, the coating layer (130) may further include a surfactant in addition to a polymer binder and inorganic particles. For example, the surfactant may be added to facilitate the casting of the coating layer composition. The surfactant may include a silicone-based surfactant. According to one embodiment, the surfactant may be a polyether-modified siloxane-based surfactant, and including this allows the coating layer composition to be coated with a more uniform thickness.

[0077] The above polyether-modified siloxane-based surfactant is a surfactant comprising a polyether chain at the end and / or side chain of a polysiloxane main chain. For example, the polyether-modified siloxane-based surfactant may comprise polyethylene oxide groups and / or polypropylene oxide groups.

[0078] These polyether-modified siloxane-based surfactants may be commercially available materials, and one or more selected from, for example, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-3450, BYK-3455, BYK-3456, BYK-3560, BYK-3565, and BYK-3760 may be used.

[0079] According to one embodiment of the present invention, the content of the surfactant in 100 parts by weight of the coating layer may be about 1 part by weight or more and 10 parts by weight or less. For example, the content of the surfactant may be about 1 part by weight or more and 9 parts by weight or less, 2 parts by weight or more and 8 parts by weight or less, 2 parts by weight or more and 7 parts by weight or less, 3 parts by weight or more and 7 parts by weight or less, 4 parts by weight or more and 7 parts by weight or less, 5 parts by weight or more and 7 parts by weight or less, or 6 parts by weight or more and 7 parts by weight or less, with respect to 100 parts by weight of the coating layer (130). By controlling the content of the surfactant within the above-described range, the effect of improving the coating properties of the coating layer can be secured.

[0080] According to one embodiment of the present invention, a solvent may be used without limitation in its composition as long as it can dissolve the above-described components, and, for example, one or more selected from water, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, propylene glycol, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl amyl ketone, cyclohexanone, cyclopentanone, diethylene glycol monomethyl ether, diethylene glycol ethyl ether, toluene, xylene, butyrolactone, carbitol, methyl cellosolve acetate, and N,N-dimethylacetamide may be used in combination. According to one embodiment, water may be used as the solvent.

[0081] According to one embodiment of the present invention, the coating layer (130) may be provided on both sides of the porous polymer substrate (110). As described above, by including the coating layer (130) provided on both sides of the porous polymer substrate (110) in the electrochemical device separator (100), the heat resistance of the separator (100) can be improved and mechanical properties can be improved.

[0082] According to one embodiment of the present invention, the coating layer (130) comprises a first coating layer (131) formed on a porous polymer substrate (110) and a second coating layer (133) formed on the first coating layer (131). For example, the coating layer (130) may form a first coating layer (131) on a porous polymer substrate (110) and then form a second coating layer (133). As described above, by including the first coating layer (131) and the second coating layer (133) formed on the first coating layer (131), the increase rate of air permeability of the separation membrane (100) can be reduced according to the formation conditions of the first coating layer (131) and the second coating layer (133), respectively.

[0083] According to one embodiment of the present invention, the first coating layer (131) and the second coating layer (133) may be formed with the same composition in terms of the type and content of the polymer binder and inorganic particles. For example, the first coating layer (131) and the second coating layer (133) may be formed by coating a coating layer slurry once on a porous polymer substrate (110) to form the first coating layer, and then coating the same coating layer slurry once again on the first coating layer (131) to form the second coating layer (133). However, due to differences in the formation process of the first coating layer (131) and the second coating layer (133), even if the first coating layer (131) and the second coating layer (133) are formed with the same composition in terms of the type and content of the polymer binder and inorganic particles, the coating layer structure and its physical properties may differ depending on the conditions under which they are formed. As described above, even if the first coating layer (131) and the second coating layer (133) are formed with the same composition in terms of the type and content of polymer binder and inorganic particles, the structure of the coating layer (130) can be controlled due to differences in the formation conditions during the formation process, thereby suppressing the increase in air permeability of the separation membrane (100) and further suppressing the increase in resistance of the separation membrane (100).

[0084] According to one embodiment of the present invention, the packing density of the coating layer (130) is about 1.70 g / cm³ 3 The following applies. For example, the packing density of the coating layer (130) is approximately 1.50 g / cm³. 3 Above 1.70 g / cm³ 3 Below, 1.51 g / cm³ 3 Above 1.69 g / cm³ 3 Below, 1.51 g / cm³ 3 Above 1.68 g / cm³ 3 Below, 1.51 g / cm³ 3 Above 1.67 g / cm³ 3 Less than or equal to 1.52 g / cm³ 3 Above 1.66 g / cm³ 3It may be less than that. By adjusting the packing density of the coating layer (130) within the above-described range, the rate of increase in air permeability of the separator (100) can be reduced.

[0085] According to one embodiment of the present invention, the packing density of the coating layer (130) may refer to how much material is contained within a specific volume. For example, if there is more material in the same volume, the packing density of the coating layer (130) may be higher, and if there is less, the packing density may be lower.

[0086] According to one embodiment of the present invention, the packing density of the first coating layer (131) is about 1.80 g / cm³ 3 It may be more than that. For example, the packing density of the first coating layer (131) is about 1.81 g / cm³ 3 Above 1.89 g / cm³ 3 Below, 1.82 g / cm³ 3 Above 1.88 g / cm³ 3 Below, 1.83 g / cm³ 3 Above 1.88 g / cm³ 3 Below, 1.84 g / cm³ 3 Above 1.88 g / cm³ 3 Below, 1.85 g / cm³ 3 Above 1.88 g / cm³ 3 Less than or equal to 1.86 g / cm³ 3 Above 1.88 g / cm³ 3 It may be less than or equal to the above. By controlling the packing density of the first coating layer (131) within the above-described range, the heat resistance of the first coating layer (131) can be secured. Furthermore, by forming a second coating layer (133) on the first coating layer (131), the packing density of the entire coating layer (130) can be lowered and the rate of increase in air permeability of the separator (100) can be reduced.

[0087] According to one embodiment of the present invention, the thickness of the first coating layer (131) may be about 0.5 μm or more and 2.5 μm or less. For example, the thickness of the first coating layer (131) may be about 0.5 μm or more and 2 μm or less, 0.6 μm or more and 1.9 μm or less, 0.7 μm or more and 1.8 μm or less, 0.8 μm or more and 1.7 μm or less, 0.9 μm or more and 1.6 μm or less, 1 μm or more and 1.5 μm or less, 1 μm or more and 1.4 μm or less, 1 μm or more and 1.3 μm or less, or 1.1 μm or more and 1.3 μm or less. By maintaining a thickness within the above-described range, the rate of increase in air permeability can be suppressed, and heat resistance can be appropriately maintained as a coating layer (130).

[0088] According to one embodiment of the present invention, the thickness of the second coating layer (133) may be about 0.5 μm or more and 2.5 μm or less. For example, the thickness of the second coating layer (133) may be about 0.6 μm or more and 2.4 μm or less, 0.7 μm or more and 2.4 μm or less, 0.8 μm or more and 2.4 μm or less, 0.9 μm or more and 2.4 μm or less, 1 μm or more and 2.4 μm or less, 1.1 μm or more and 2.4 μm or less, or 1.2 μm or more and 2.4 μm or less. By maintaining a thickness within the above-described range, the rate of increase in air permeability can be suppressed, and heat resistance can be appropriately maintained as a coating layer (130).

[0089] In one embodiment of the present invention, the thickness of the coating layer (130), etc., can be measured by applying a contact-type thickness gauge. For example, the contact-type thickness gauge may use the VL-50S-B from Mitutoyo.

[0090] According to one embodiment of the present invention, the air permeability of the separator (100) may be 150% or less relative to the air permeability of the porous polymer substrate (110). For example, the air permeability of the separator (100) may be about 100% or more and 150% or less, 100% or more and 148% or less, 100% or more and 146% or less, 100% or more and 144% or less, 100% or more and 142% or less, 100% or more and 140% or less, 105% or more and 140% or less, 110% or more and 140% or less, 115% or more and 140% or less, 120% or more and 140% or less, 125% or more and 140% or less, or 129% or more and 140% or less relative to the air permeability of the porous polymer substrate (110). By maintaining the air permeability within the aforementioned range, the increase in separator resistance caused by obstacles blocking the lithium ion movement pathway can be suppressed.

[0091] According to one embodiment of the present invention, the air permeability of the separator (100) may be about 100 s / 100cc or less. For example, the air permeability of the separator (100) may be about 70 s / 100cc or more and 100 s / 100cc or less, 70 s / 100cc or more and 99 s / 100cc or less, 70 s / 100cc or more and 98 s / 100cc or less, 75 s / 100cc or more and 98 s / 100cc or less, 80 s / 100cc or more and 98 s / 100cc or less, 85 s / 100cc or more and 98 s / 100cc or less, or 90 s / 100cc or more and 98 s / 100cc or less. In the above-mentioned range of air permeability, the increase in resistance caused by obstruction of lithium ion movement pathways by inorganic particles included in the coating layer can be suppressed.

[0092] One embodiment of the present invention comprises a method for manufacturing a separator (100) for an electrochemical device, the method comprising: a step of providing a porous polymer substrate (110); a step of forming a first coating layer (131) by applying a coating layer slurry to at least one surface of the porous polymer substrate (110) and drying it; and a step of forming a second coating layer (133) by applying a coating layer slurry to the first coating layer (131) and drying it, wherein the drying temperature is approximately 40°C to 80°C.

[0093] A method for manufacturing a separator for an electrochemical device according to one embodiment of the present invention can minimize the rate of increase in air permeability of the separator (100) and suppress the increase in resistance by controlling the drying conditions after applying a slurry for a coating layer.

[0094] According to one embodiment of the present invention, when forming the coating layer (130), a coating layer slurry can be prepared by dispersing the polymer binder and inorganic particles in water. Subsequently, a first coating layer (131) can be formed by applying the coating layer slurry to one surface of the porous polymer substrate (110) and drying it, and a second coating layer (133) can be formed by applying the coating layer slurry to the first coating layer (131) and drying it.

[0095] According to one embodiment of the present invention, the drying may be performed by moving to a heating zone to dry a coating layer slurry applied to one surface of the porous polymer substrate (110) to form a coating layer (130). The porous polymer substrate coated with the coating layer slurry may be dried while moving through a heating zone heated to a predetermined temperature at a predetermined speed to form a separation membrane (100) having a coating layer (130). For example, the heating temperature of the heating zone may be about 40°C to 80°C. The porous polymer substrate (110) coated with the coating layer slurry may move through the heating zone at a speed of about 5 m / min to 30 m / min.

[0096] According to one embodiment of the present invention, the drying temperature during the formation of the first coating layer (131) may be lower than the drying temperature during the formation of the second coating layer (133). As described above, by selecting a drying temperature lower than the drying temperature during the formation of the second coating layer (133) for the formation of the first coating layer (131), the heat resistance characteristics of the coating layer during the formation of the first coating layer (131) can be secured, and the packing density of the separator during the formation of the second coating layer (133) can be reduced to decrease the rate of increase in air permeability of the separator, thereby suppressing the increase in resistance.

[0097] According to one embodiment of the present invention, the drying temperature when forming the first coating layer (131) may be approximately 40°C or higher and 50°C or lower. For example, the drying temperature when forming the first coating layer (131) may be approximately 41°C or higher and 49°C or lower, 42°C or higher and 48°C or lower, 43°C or higher and 47°C or lower, or 44°C or higher and 46°C or lower, and according to one embodiment, may be approximately 45°C. By controlling the drying temperature when forming the first coating layer (131) within the above-described range, the heat resistance characteristics of the coating layer (130) when forming the first coating layer (131) can be secured.

[0098] According to one embodiment of the present invention, the drying temperature when forming the second coating layer (133) may be approximately 60°C or higher and 80°C or lower. For example, the drying temperature when forming the second coating layer (133) may be approximately 61°C or higher and 79°C or lower, 62°C or higher and 78°C or lower, 63°C or higher and 77°C or lower, or 64°C or higher and 76°C or lower, and according to one embodiment, may be approximately 70°C. By controlling the drying temperature when forming the second coating layer (133) within the above-described range, the packing density of the separator when forming the second coating layer (133) is reduced, thereby reducing the rate of increase in air permeability of the separator and thereby suppressing the increase in resistance.

[0099] One embodiment of the present invention includes an electrochemical element comprising: an anode; a cathode; and one of the aforementioned separators interposed between the anode and the cathode. In the electrochemical element according to one embodiment of the present invention, details that overlap with the description of the separator (100) for the electrochemical element are omitted.

[0100] An electrochemical device according to one embodiment of the present invention can suppress the increase in resistance by minimizing the rate of increase in air permeability of a separator (100) including a coating layer (130).

[0101] In one embodiment of the present invention, the electrochemical element is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept that encompasses primary batteries and secondary batteries. In this specification, the secondary battery is capable of charging and discharging and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples include a non-aqueous electrolyte secondary battery containing a liquid electrolyte, an all-solid-state battery containing a solid electrolyte, a lithium polymer battery containing a gel polymer electrolyte, and a lithium metal battery using lithium metal as a negative electrode, but are not limited thereto.

[0102] According to one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer comprising a positive electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The positive electrode active material is a layered compound such as a lithium manganese complex oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-xLithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn1-xM x It may include a lithium manganese complex oxide represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which part of the Li of the chemical formula is substituted with alkaline earth metal ions; a disulfide compound; and one or more of Fe2(MoO4)3.

[0103] According to one embodiment of the present invention, the cathode comprises a cathode current collector and a cathode active material layer comprising a cathode active material, a conductive material, and a binder resin on at least one surface of the current collector. The cathode comprises, as the cathode active material, carbon such as lithium metal oxide, non-graphitizable carbon, or graphite-based carbon; LixFe2O3 (0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0104] According to one embodiment of the present invention, the conductive material may be, for example, any one selected from the group consisting of graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whiskers, conductive metal oxide, activated carbon, and polyphenylene derivative, or a mixture of two or more of these conductive materials. More specifically, it may be one selected from natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more of these conductive materials.

[0105] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used.

[0106] According to one embodiment of the present invention, the binder resin may be a polymer commonly used in the industry for electrodes. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include acetatepropionate), cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose, but are not limited thereto.

[0107] According to one embodiment of the present invention, the anode slurry for manufacturing the anode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (N-methylpyrrolidone, ADC-01, LG Chem).

[0108] According to one embodiment of the present invention, the electrochemical element may further include an electrolyte, and the electrolyte is A + B - As a salt with a structure like that, A + is Li + , Na + , K + It may include alkali metal cations such as or ions composed of a combination thereof. In addition, B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - A salt comprising an anion such as or a combination thereof may be dissolved or dissociated in an organic solvent comprising propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethylmethyl carbonate (EMC), gamma butyrolactone, or a mixture thereof, but is not limited thereto.

[0109] According to one embodiment of the present invention, a battery module comprising a battery including the electrochemical element as a unit cell, a battery pack comprising the battery module, and a device comprising the battery pack as a power source may be provided. Examples of the device include, but are not limited to, a power tool that moves by receiving power from a battery motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) or an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0110] Hereinafter, the present invention will be described in detail with reference to examples to explain the invention in more detail. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0111]

[0112] <Example 1>

[0113] Manufacturing of porous polymer substrates

[0114] A polyethylene resin (weight-average molecular weight 1.5 million) was extruded, and a porous polymer substrate (total thickness 9.1 μm, air permeability 70 s / 100cc) was prepared by a wet method.

[0115] Formation of a coating layer

[0116] As inorganic particles, Al2O3 (AES 11, Sumitomo) with a D50 particle size of 500 nm was prepared. As polymer binders, an acrylic copolymer (CSB-140, Toyo) and a silicone surfactant (BYK-348, BYK) with a D50 particle size of 150 nm were prepared.

[0117] The above-mentioned prepared inorganic particles, polymer binder, and surfactant were added to water in a weight ratio of 87.5:6.25:6.25 and dispersed to prepare a slurry for a coating layer.

[0118] The slurry for the coating layer was applied to one surface of the porous polymer substrate using a doctor blade in a bar coating method and the first coating was applied.

[0119] The above first coated porous polymer substrate was introduced into five heating zones at a temperature of 45°C and dried while moving at a speed of 5 m / min to 30 m / min to form a first coating layer with a thickness of 1.3 μm.

[0120] Afterwards, the slurry for the coating layer was applied to the first coating layer using a doctor blade in a bar coating method, and a second coating was applied.

[0121] The above second coated porous polymer substrate was introduced into a heating zone at a temperature of 70 ℃ and dried while moving at a speed of 5 m / min to 30 m / min to form a second coating layer with a thickness of 2.4 μm, and a separation membrane with a total thickness of 12.8 μm was manufactured.

[0122]

[0123] <Example 2>

[0124] In the above Example 1, a separator was manufactured in the same manner as in Example 1, except that the thickness of the first coating layer was 1.1 μm, the thickness of the second coating layer was 1.2 μm, and the total thickness was 11.4 μm.

[0125]

[0126] <Comparative Example 1>

[0127] In the above Example 1, a separator was manufactured in the same manner as in Example 1, except that the thickness of the first coating layer was 1.8 μm, the thickness of the second coating layer was 2.5 μm, and the total thickness was 13.4 μm.

[0128]

[0129] <Comparative Example 2>

[0130] Manufacturing of porous polymer substrates

[0131] A polyethylene resin (weight-average molecular weight 1.5 million) was extruded, and a porous polymer substrate (total thickness 9.1 μm, air permeability 70 s / 100cc) was prepared by a wet method.

[0132] Formation of a coating layer

[0133] As inorganic particles, Al2O3 (AES 11, Sumitomo) with a D50 particle size of 500 nm was prepared. As polymer binders, an acrylic copolymer (CSB-140, Toyo) and a silicone surfactant (BYK-348, BYK) with a D50 particle size of 150 nm were prepared.

[0134] The above-mentioned prepared inorganic particles, polymer binder, and surfactant were added to water in a weight ratio of 87.5:6.25:6.25 and dispersed to prepare a slurry for a coating layer.

[0135] The slurry for the coating layer was applied to one surface of the above porous polymer substrate by a bar coating method using a doctor blade.

[0136] Subsequently, the coated porous polymer substrate was introduced into five heating zones at temperature conditions of 40 ℃, 40 ℃, 50 ℃, 70 ℃, and 70 ℃, respectively, and dried while moving at a speed of 5 to 30 m / min to form a coating layer with a thickness of 3.5 μm, thereby producing a separator with a total thickness of 12.6 μm.

[0137]

[0138] <Comparative Example 3>

[0139] In Comparative Example 2 above, a separator was prepared in the same manner as in Comparative Example 2, except that the drying conditions were different during the formation of the coating layer as follows.

[0140] The above-mentioned coated porous polymer substrate was introduced into a heating zone at a temperature of 45°C and dried while moving at a speed of 5 to 30 m / min to form a coating layer with a thickness of 3.3 μm, thereby producing a separator with a total thickness of 12.4 μm.

[0141]

[0142] <Experimental Example>

[0143] Air permeability measurement

[0144] For the separators of the above examples and comparative examples, air permeability was measured using a Gurley densometer (Gurley, 4110N) with 100 cc of air having a diameter of 28.6 mm and an area of ​​645 mm² 2 The time (s) taken to pass through the membrane was measured.

[0145]

[0146] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Substrate Air Permeability (s / 100cc) 70 70 70 70 70 Separator Air Permeability (s / 100cc) 1st Layer 8 3 8 3 9 0 1 1 0 1 2 6 2nd Layer 9 8 9 0 1 0 6 Air Permeability Increase Rate (%) 1 4 0 1 2 9 1 5 1 1 5 7 1 8 0 Coating Layer Drying Temperature Conditions 1st Layer 45 ℃ 45 ℃ 45 ℃ Initial Temperature Low 45 ℃ 2nd Layer 70 ℃ 70 ℃ 70 ℃ Coating Layer Packing Density (g / cm²) 3 )1st layer 1.86 1.88 1.87 1.7 11.84 Total 1.5 21.6 61.63 Coating layer loading amount (g / m 2 )1st layer 2.4 2.0 7 3.3 6 5.9 9 6.0 72nd layer 5.6 2.3 8 2.7 0 2 Coating layer thickness (㎛) 1st layer 1.3 1.1 1.8 3.5 3.3 2nd layer 2.4 1.2 2.5 Separator thickness (㎛) 12.8 11.4 13.4 12.6 12.4

[0147]

[0148] According to Table 1 above, in Examples 1 and 2, when forming the coating layer (130) of the separator (100), the packing density of the first coating layer (131) and the second coating layer (133) is controlled so that the increase rate of the air permeability of the separator (100) with the coating layer (130) formed is minimized relative to the air permeability of the porous polymer substrate (110), so that the air permeability of the separator (100) is 100 s / 100cc or less.

[0149] Additionally, according to FIG. 2, it can be seen that in the first coating layer (131) of Example 1, the drying speed of the slurry is slow at a low drying temperature, so the inorganic particles within the first coating layer (131) are densely packed, and in the second coating layer (133), the drying speed of the slurry is fast at a high drying temperature, so the inorganic particles within the second coating layer (133) are formed relatively less densely compared to the first coating layer (131).

[0150] In contrast, in Comparative Example 1, even if the drying temperature conditions when forming the coating layer (130) are the same as those of the above example, it can be seen that the increase rate of the air permeability of the separation membrane (100) relative to the air permeability of the porous polymer substrate (110) is increased as the thickness of the coating layer (130) increases.

[0151] Unlike the above example and the coating layer (130) formation conditions, the above Comparative Example 2 does not form a second coating layer (133). When forming the coating layer (130), the initial temperature is set low under drying temperature conditions, so that drying is slow, most of the inorganic particles settle and become densely distributed. Subsequently, by setting the temperature to a high level, it can be seen that the rate of increase in air permeability due to high-temperature shrinkage increases. In addition, it can be seen that the packing density has increased compared to the above example.

[0152] Unlike the above example and the coating layer (130) formation conditions, the above comparative example 3 does not form a second coating layer (133), and when forming the coating layer (130), the drying temperature is kept low so that drying is slow, causing inorganic particles to settle and become densely distributed. Consequently, the rate of increase in air permeability of the separator (100) increases, and thus, an increase in resistance can be predicted. In addition, it can be seen that the packing density has increased compared to the above example.

[0153] In addition, according to FIG. 3, it can be seen that in Comparative Example 3, when forming the coating layer (130), the drying speed of the slurry is slow at a low drying temperature, so the inorganic particles in the coating layer (130) are densely packed.

[0154] Accordingly, the electrochemical device separator (100) according to one embodiment of the present invention, the electrochemical device including the same, and the method for manufacturing the same can control the increase in air permeability of the separator (100) and further suppress the increase in resistance of the separator (100) by controlling the structure of the coating layer (130).

[0155] Although the foregoing has been described with reference to the embodiments of the present disclosure, a person skilled in the art or having ordinary knowledge in the art will understand that various modifications and changes can be made to the various embodiments of the present disclosure without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

[0156] [Explanation of the symbol]

[0157] 100: Separator for electrochemical devices

[0158] 110: Porous polymer substrate

[0159] 130: Coating layer

[0160] 131: First coating layer

[0161] 133: Second coating layer

Claims

1. Porous polymer substrate; and A coating layer provided on at least one surface of the above-mentioned porous polymer substrate and comprising a polymer binder and inorganic particles; The above coating layer includes a first coating layer and a second coating layer formed on the first coating layer, and The packing density of the above coating layer is 1.70 g / cm³ 3 Separator for electrochemical devices.

2. In Claim 1, A separator for an electrochemical device, wherein the thickness of the porous polymer substrate is 8 μm or more and 15 μm or less.

3. In Claim 1, The packing density of the first coating layer is 1.80 g / cm³ 3 A separator for an electrochemical device that is the above.

4. In Claim 1, The thickness of the first coating layer is 0.5 μm or more and 2.5 μm or less, and A separator for an electrochemical device, wherein the thickness of the second coating layer is 0.5 μm or more and 2.5 μm or less.

5. In Claim 1, A separator for an electrochemical device, wherein the air permeability of the separator is 150% or less compared to the air permeability of the porous polymer substrate.

6. In Claim 1, A separator for an electrochemical device, wherein the air permeability of the porous polymer substrate is 50 s / 100cc or more and 80 s / 100cc or less.

7. In Claim 1, A separator for an electrochemical device, wherein the air permeability of the separator is 100 s / 100cc or less.

8. In Claim 1, A separator for an electrochemical device, wherein the content of the inorganic particles in 100 parts by weight of the coating layer is 80 parts by weight or more and 95 parts by weight or less.

9. In Claim 1, A separator for an electrochemical device, wherein the content of the polymer binder in 100 parts by weight of the coating layer is 1 part by weight or more and 10 parts by weight or less.

10. In Claim 1, A separator for an electrochemical device, wherein the first coating layer and the second coating layer are formed with the same composition of polymer binder and inorganic particles in terms of type and content.

11. A step of providing a porous polymer substrate; A step of forming a first coating layer by applying a slurry for a coating layer to at least one surface of the porous polymer substrate and drying it; and The method includes the step of forming a second coating layer by applying a coating layer slurry onto the first coating layer and drying it; A method for manufacturing a separator for an electrochemical device, wherein the drying temperature is 40 ℃ to 80 ℃.

12. In Claim 11, A method for manufacturing a separator for an electrochemical device, wherein the drying temperature when forming the first coating layer is lower than the drying temperature when forming the second coating layer.

13. In Claim 12, A method for manufacturing a separator for an electrochemical device, wherein the drying temperature when forming the first coating layer is 40 ℃ or higher and 50 ℃ or lower.

14. In Claim 12, A method for manufacturing a separator for an electrochemical device, wherein the drying temperature when forming the second coating layer is 60 ℃ or higher and 80 ℃ or lower.

15. An electrochemical device comprising: an anode; a cathode; and a separator of claim 1 interposed between the anode and the cathode.

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