Separator for electrochemical device and electrochemical device including the same

Abstract

The separator for an electrochemical device includes a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate. The porous coating layer includes inorganic particles and a polymer binder. The inorganic particles have a polymer coating layer containing amine groups formed on their surfaces, and at least a portion of the polymer binder is crosslinked with the polymer containing amine groups.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2023-0038901, filed with the Korean Intellectual Property Office on March 24, 2023, the entire contents of which are incorporated herein by reference. The present invention relates to a separator for an electrochemical device and an electrochemical device including the same. [Background technology]

[0002] Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions, and in recent years, lithium secondary batteries have been widely used because they have high energy density, high voltage, long cycle life, and can be used in a variety of fields.

[0003] The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and may be manufactured by housing the electrode assembly together with an electrolyte in a case.

[0004] Meanwhile, in order to improve the performance and safety of secondary batteries using electrochemical devices, improvements have been made to the characteristics of the positive electrode, negative electrode, electrolyte, and separator. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a separator for an electrochemical device that exhibits reduced dimensional change in a high-temperature wet state, a method for manufacturing the same, and an electrochemical device including the separator for an electrochemical device.

[0006] 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 following description. [Means for solving the problem]

[0007] One aspect of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer comprising inorganic particles and a polymer binder, the inorganic particles having a polymer coating layer containing an amine group formed on surfaces of the inorganic particles, and at least a portion of the polymer binder being crosslinked with the polymer containing the amine group.

[0008] According to one embodiment of the present invention, the polymer containing an amine group is dopamine or a derivative thereof.

[0009] According to one embodiment of the present invention, the polymer coating layer has a thickness of about 2 nm to 20 nm.

[0010] According to one embodiment of the present invention, the polymer binder includes at least one selected from the group consisting of dextrin, polyetheretherketone, polyethersulfone, and polyacrylamide.

[0011] According to one embodiment of the present invention, the polymer binder comprises a (co)polymer of a monomer selected from the group consisting of acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and carboxyethyl acrylate.

[0012] According to one embodiment of the present invention, about 60% to 80% by weight of the polymer binder is crosslinked with the polymer containing amine groups.

[0013] According to one embodiment of the present invention, the loading amount of the porous coating layer per unit area of ​​the porous polymer substrate is about 5.5 g / m 2 ~8g / m 2 is.

[0014] According to one embodiment of the present invention, the porous coating layer includes the inorganic particles in an amount of about 90 wt % to 95 wt % based on the total weight of the porous coating layer.

[0015] According to one embodiment of the present invention, the porous coating layer may further include a second polymer coating layer formed on the surface of the porous coating layer, the second polymer coating layer including the polymer having the amine group.

[0016] According to one embodiment of the present invention, at least a portion of the polymer containing the amine group of the second polymer coating layer is crosslinked with the polymer binder of the porous coating layer.

[0017] According to one embodiment of the present invention, the second polymer coating layer further includes dextrin.

[0018] According to another embodiment of the present invention, there is provided an electrochemical device including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is the separator for an electrochemical device according to the above aspect.

[0019] The electrochemical device may be a lithium secondary battery. [Effects of the Invention]

[0020] The separator for an electrochemical device according to one embodiment of the present invention exhibits improved dimensional stability in a wet state when impregnated with an electrolyte. For example, the separator exhibits a thermal shrinkage rate of less than 10% in the transverse direction at high temperatures of about 130°C or higher, thereby preventing exposure of electrodes due to thermal shrinkage of the separator. [Brief explanation of the drawings]

[0021] [Figure 1a] According to an experimental example, the separator according to Example 1 was inserted into a pouch together with an electrolyte solution, and after storing it in a convection oven at 135°C for 30 minutes, the separator was taken out and its outer shape was confirmed. This is an image of this. [Figure 1b] According to an experimental example, the separator according to Comparative Example 1 was inserted into a pouch together with an electrolyte solution and stored in a convection oven at 135°C for 30 minutes, and then the separator was taken out and its outer shape was confirmed. This is an image of this.

[0022] Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of the various embodiments, the dimensions of some elements shown in the drawings may be exaggerated relative to other elements. Furthermore, elements of the known art that are useful or essential in commercially viable embodiments are often not depicted so as not to obscure the spirit of the various embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, each configuration of the present invention will be described in more detail so that a person having ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited by the following content.

[0024] As used herein, the term "comprising" is used to list materials, compositions, devices, and methods useful in the present invention, without limiting the examples listed.

[0025] In this specification, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise.

[0026] In this specification, "A and / or B" means "A and B, or A or B."

[0027] In this specification, when a component is said to be "provided on" another component, this does not exclude other components from being disposed therebetween, but means that other components may be further disposed thereon, unless otherwise specified.

[0028] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0029] As used in this specification, the terms "about" and "substantially" are used to mean a range of values ​​or degrees, or something close to that range, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly taking advantage of the disclosure in which exact or absolute values ​​are mentioned, which are provided to aid in the understanding of the present invention.

[0030] As used herein, "electrochemical device" refers to a primary battery, a secondary battery, a supercapacitor, and the like.

[0031] As used herein, the term "wet state" refers to a state in which the separator is at least partially immersed in the electrolyte solution.

[0032] The separator may include a porous coating layer on at least one surface of a porous substrate, the porous coating layer including a polymer binder and inorganic particles. The inorganic particles are connected to other inorganic particles by the polymer binder to form interstitial volumes through which lithium ions can migrate. In addition to immobilizing the inorganic particles, the polymer binder may also impart adhesive strength to the porous coating layer, allowing the porous coating layer to adhere to the porous substrate and the electrode, respectively.

[0033] A porous coating layer containing a polymer binder and inorganic particles can prevent thermal shrinkage of the porous polymer substrate, and a separator containing the porous coating layer exhibits excellent dimensional stability in a dry state without electrolyte. However, in a wet state where the separator is impregnated with electrolyte, the adhesive strength of the polymer binder decreases due to swelling caused by the electrolyte or exposure to temperatures above 130°C during operation of a lithium secondary battery containing the separator. In such a high-temperature wet state, the adhesive strength of the porous coating layer decreases, causing the separator to shrink significantly. In particular, cylindrical batteries, in which an electrode assembly is wound and inserted into a case under tension, require relatively weaker adhesive strength between the electrodes and the separator than pouch-type batteries. Therefore, the polymer binder content is lower, resulting in poorer dimensional stability in a wet state.

[0034] To prevent this problem, the present invention provides a separator that maintains dimensional stability under high temperature and wet conditions while maintaining a relatively low content of polymer binder in the porous coating layer.

[0035] One embodiment of the present invention provides a separator for an electrochemical device, comprising: a porous polymer substrate; and a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer comprising inorganic particles and a polymer binder, the inorganic particles having a polymer coating layer containing amine groups formed on their surfaces, and at least a portion of the polymer binder being crosslinked with the polymer containing amine groups.

[0036] According to one embodiment of the present invention, the porous polymer substrate is a porous film having a plurality of pores formed therein, and electrically insulates the positive and negative electrodes to prevent short circuits. For example, when the electrochemical device is a lithium secondary battery, the porous polymer substrate serves as an ion-conductive barrier that blocks electrical contact between the positive and negative electrodes while allowing lithium ions to pass through. At least some of the pores may form a three-dimensional network that connects the surface and interior of the porous polymer substrate, allowing fluid to pass through the porous polymer substrate via the pores.

[0037] According to one embodiment of the present invention, the porous polymer substrate is made of a material that is physically and chemically stable with respect to the electrolyte, which is an organic solvent. For example, the porous polymer substrate may be made of a resin such as, but not limited to, polyolefins such as polyethylene, polypropylene, and polybutylene, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof. For example, a polyolefin-based resin may be used. Polyolefin-based resins can be processed to a relatively thin thickness and are easy to apply a coating slurry to, making them suitable for manufacturing electrochemical devices with higher energy density.

[0038] According to one embodiment of the present invention, the porous polymer substrate has a single-layer or multi-layer structure. The porous polymer substrate includes two or more polymer resin layers with different melting points (Tm), thereby providing a shutdown function during high-temperature runaway of the battery. For example, the porous polymer substrate includes a polypropylene layer with a relatively high melting point and a polyethylene layer with a relatively low melting point. Alternatively, the porous polymer substrate may have a three-layer structure in which polypropylene, polyethylene, and polypropylene are laminated in this order. The polyethylene layer melts as the battery temperature rises above a predetermined temperature, thereby shutting down the pores and preventing thermal runaway of the battery.

[0039] According to one embodiment of the present invention, the thickness of the porous polymer substrate is about 1 μm to 100 μm. For example, the thickness of the porous polymer substrate may be about 10 μm to 90 μm, about 20 μm to 80 μm, about 30 μm to 70 μm, or about 40 μm to 60 μm. Alternatively, the thickness of the polymer substrate may be about 1 μm to 30 μm. For example, the thickness of the polymer substrate may be about 5 μm to 15 μm, or about 8 μm to 13 μm. By adjusting the thickness of the porous polymer substrate within the above range, the volume of the electrochemical device can be minimized and the amount of active material contained in the electrochemical device can be increased while electrically insulating the positive and negative electrodes.

[0040] According to one embodiment of the present invention, the porous polymer substrate includes pores having an average diameter of about 0.01 μm to 1 μm. For example, the size of the pores in the porous polymer substrate may be about 0.01 μm to 0.09 μm, about 0.02 μm to 0.08 μm, about 0.03 μm to 0.07 μm, or about 0.04 μm to 0.06 μm. Alternatively, the size of the pores may be about 0.02 μm to 0.06 μm. By adjusting the pore size of the porous polymer substrate within the above ranges, the air permeability and ionic conductivity of the entire separator membrane can be adjusted.

[0041] According to one embodiment of the present invention, the porous polymer substrate has an air permeability of about 10 s / 100 cc to 100 s / 100 cc. For example, the air permeability of the porous polymer substrate may be about 10 s / 100 cc to 90 s / 100 cc, about 20 s / 100 cc to 80 s / 100 cc, about 30 s / 100 cc to 70 s / 100 cc, or about 40 s / 100 cc to 60 s / 100 cc. Alternatively, the air permeability of the porous polymer substrate may be about 50 s / 100 cc to 70 s / 100 cc. When the air permeability of the porous polymer substrate is within the above range, the air permeability of the resulting separator can be provided within a range suitable for ensuring the output and cycle characteristics of an electrochemical device.

[0042] According to one embodiment of the present invention, the air permeability (s / 100cc) refers to the time (seconds) it takes for 100cc of air to pass through a porous polymer substrate or separator with a given area under a certain pressure. The air permeability can be measured using a Gurley densometer in accordance with ASTM D 726-58, ASTM D726-94, or JIS-P8117. For example, a Gurley 4110N device is used to measure air at a pressure of 0.304kPa or 1.215kN / m. 2 100cc of air under pressure of 1 square inch (or 6.54cm) of water 2 For example, using an Asahi Seiko EG01-55-1MR instrument, the time it takes for 100 cc of air to pass through a 1 sq. inch sample at room temperature under a constant pressure of 4.8 inches of water can be measured.

[0043] According to one embodiment of the present invention, the porous polymer substrate has a porosity of about 10 vol% to about 60 vol%. For example, the porosity of the porous polymer substrate may be about 15 vol% to about 55 vol%, about 20 vol% to about 50 vol%, about 25 vol% to about 45 vol%, or about 30 vol% to about 40 vol%. Alternatively, the porosity of the porous polymer substrate may be about 30 vol% to about 50 vol%. When the porosity of the porous polymer substrate is within the above range, the ionic conductivity of the resulting separator can be provided within a range suitable for ensuring the output and cycle characteristics of an electrochemical device.

[0044] According to one embodiment of the present invention, the porosity refers to the ratio of the volume of pores to the total volume of a porous polymer substrate. The porosity can be measured by methods known in the art, such as the Brunauer-Emmett-Teller (BET) method using nitrogen gas adsorption, capillary flow porosimetry, or water or mercury penetration.

[0045] According to one embodiment of the present invention, the porous coating layer is formed on at least one surface of the porous polymer substrate and includes inorganic particles and a polymer binder.

[0046] According to one embodiment of the present invention, the porous coating layer is formed by coating at least one surface of a porous polymer substrate with a coating slurry containing inorganic particles, a polymer binder, and a dispersion medium. For example, the separator may be manufactured by applying the coating slurry to at least one surface of a porous polymer substrate and then drying the coating slurry to remove the dispersion medium. The porous coating layer includes interstitial volumes in which the inorganic particles are connected by the polymer binder, and adheres to the porous polymer substrate while allowing lithium ions to pass through, thereby preventing thermal shrinkage of the porous polymer substrate.

[0047] According to one embodiment of the present invention, the coating slurry includes a dispersion medium that dissolves or disperses at least a portion of the polymer binder and disperses the inorganic particles. The coating slurry is used in which the polymer binder and the inorganic particles are uniformly dispersed by adjusting the type and content of the dispersion medium. For example, the dispersion medium is one selected from the group consisting of water, ethanol, acetone, isopropyl alcohol (IPA), dimethylacetamide (DMAc), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), acetonitrile, and combinations thereof. Using the above-mentioned types of dispersion medium, a porous coating layer in which the inorganic particles are uniformly dispersed can be formed.

[0048] According to one embodiment of the present invention, the coating slurry has a viscosity of about 100 cps to about 1,000 cps. For example, the viscosity of the coating slurry may be about 200 cps to about 900 cps, about 300 cps to about 800 cps, about 400 cps to about 700 cps, or about 500 cps to about 600 cps. Alternatively, the viscosity of the coating slurry may be about 300 cps to about 800 cps. By adjusting the viscosity of the coating slurry within the above range, a porous coating layer can be formed by continuously applying the coating slurry to a porous polymer substrate.

[0049] According to one embodiment of the present invention, the coating slurry further includes additives such as a dispersant, a surfactant, an antifoaming agent, and a flame retardant to improve dispersibility and flame retardancy and improve the uniformity of the porous coating layer formed. For example, the dispersant may include at least one selected from the group consisting of oil-soluble polyamines, oil-soluble amine compounds, fatty acids, fatty alcohols, sorbitan fatty acid esters, tannic acid, and pyrogallic acid. The use of the above-mentioned types of dispersants can improve the stability of the coating slurry and ensure the uniformity of the porous coating layer formed from the coating slurry.

[0050] According to one embodiment of the present invention, the additive is included in an amount of about 0 to 5 wt % based on the total weight of the coating slurry. For example, the additive may be included in an amount of about 0.01 to 4 wt %, about 0.1 to 3 wt %, or about 1 to 2 wt %. Alternatively, the additive may be included in an amount of about 3 to 5 wt %. By adjusting the additive content within the above range, uniform dispersion and stability of the inorganic particles included in the coating slurry can be achieved.

[0051] According to one embodiment of the present invention, the dispersion medium contained in the coating slurry is removed by drying or heating after the formation of the porous coating layer. For example, the porous coating layer may contain a dispersion medium at about 5 ppm or less. Alternatively, the porous coating layer may be composed of an acrylic polymer binder, a copolymer binder, and inorganic particles. During the process of removing the dispersion medium, multiple pores are formed on the surface and inside of the porous coating layer. The pores include interstitial volumes formed between the inorganic particles, forming a three-dimensional network structure that allows fluid to pass through.

[0052] According to one embodiment of the present invention, the thickness of the porous coating layer is about 0.1 μm to 10 μm. For example, the thickness of the porous coating layer may be about 0.5 μm to 9.5 μm, about 1.0 μm to 9.0 μm, about 1.5 μm to 8.5 μm, about 2.0 μm to 8.0 μm, about 2.5 μm to 7.5 μm, about 3.0 μm to 7.0 μm, about 3.5 μm to 6.5 μm, about 4.0 μm to 6.0 μm, or about 4.5 μm to 5.5 μm. Alternatively, the thickness of the porous coating layer may be about 0.5 μm to 5 μm. Alternatively, the thickness of the porous coating layer may be about 0.5 μm to 2 μm. By adjusting the thickness of the porous coating layer within the above range, shrinkage of the porous polymer substrate can be minimized and stable adhesion to the porous polymer substrate can be achieved.

[0053] According to one embodiment of the present invention, the porous coating layer includes inorganic particles having a polymer coating layer containing amine groups formed on their surfaces and a polymer binder, at least a portion of which is crosslinked with the polymer containing amine groups. For example, the polymer binder may include two or more different polymer binders, at least one of which may be crosslinked with the polymer containing amine groups. The polymer binder crosslinked with the polymer containing amine groups forms a physical or chemical bond with the polymer containing amine groups. Alternatively, the polymer binder crosslinked with the polymer containing amine groups may be thermally crosslinked via the amine groups. The polymer binder is bound to one or more inorganic particles through crosslinking with the coating layer of the inorganic particles to form an interstitial volume. The polymer binder forms and maintains a stronger bond with the inorganic particles having the coating layer than inorganic particles without the coating layer, and the porous coating layer including the polymer binder may exhibit reduced thermal shrinkage in a high-temperature wet state.

[0054] According to one embodiment of the present invention, the inorganic particles are electrochemically stable. The inorganic particles are selected from those having a stable electrochemical voltage range (e.g., Li / Li + There are no particular limitations on the inorganic particles, as long as they do not undergo oxidation and / or reduction reactions at a voltage (0 to 5 V relative to the reference voltage). For example, when inorganic particles with a high dielectric constant are used as the inorganic particles, they contribute to an increase in the degree of dissociation of the electrolyte salt, for example, lithium salt, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte. For the reasons mentioned above, it is preferable that the inorganic particles include inorganic particles with a high dielectric constant, having a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles with a dielectric constant of 5 or more include BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3)Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, Al(OH)3, SiC, AlOOH, TiO2, or mixtures thereof.

[0055] In addition, as the inorganic particles, inorganic particles having lithium ion transfer ability, that is, inorganic particles containing lithium element but having a function of moving lithium ions without storing lithium can be used. Non-limiting examples of inorganic particles having lithium ion transfer ability include lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li[[ID=⑨]] x [[ID=⑩]]Al[[ID=⑪]] y [[ID=⑫]]Ti[[ID=⑬]] z [[ID=⑭]](PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP)[[ID=⑮]] x [[ID=⑯]]O[[ID=⑰]] y [[ID=⑱]]-based glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li[[ID=⑲]] x [[ID=⑳]]La[[ID=㉑]] y [[ID=㉒]]TiO3, 0 < x < 2, 0 < y < 3), Li[[ID=㉓]] 3.25 [[ID=㉔]]Ge[[ID=㉕]] 0.25 [[ID=㉖]]P[[ID=㉗]] 0.75 [[ID=㉘]]S4, etc., such as lithium germanium thiophosphate (Li[[ID=㉙]] x [[ID=㉚]]Ge[[ID=㉛]] y [[ID=㉜]]P[[ID=㉝]] z [[ID=㉞]]S[[ID=㉟]] w [[ID=㊱]] (Li[[ID=㊲]] x [[ID=㊳]]N[[ID=㊴]] y [[ID=㊵]] (Li[[ID=㊶]] x [[ID=㊷]]Si[[ID=㊸]] y [[ID=㊹]]S[[ID=㊺]] z [[ID=㊻]] (Li[[ID=㊼]] x [[ID=㊽]]P[[ID=㊾]] y [[ID=㊿]]S z, (0 < x < 3, 0 < y < 3, 0 < z < 7), or a mixture thereof, etc.

[0056] In addition, as the inorganic particles, inorganic particles having flame retardancy can be used, which can impart flame retardant properties to the separation membrane or prevent the temperature inside the electrochemical device from rising rapidly. Non-limiting examples of the inorganic particles having flame retardancy include Sb2O3, Sb2O4, Sb2O5, SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, Zn2SnO4, ZnSnO3, ZnSn(OH)6, ZrO2, Y2O3, SiO2, Al2O3, AlOOH, Al(OH)3, SiC, TiO2, H3BO3, HBO2, and mixtures thereof.

[0057] According to an embodiment of the present invention, the average particle diameter (D50) of the inorganic particles is about 50 nm or more and 5,000 nm or less. For example, the average particle diameter (D50) of the inorganic particles can be about 100 nm or more and 4,500 nm or less, about 200 nm or more and 4,000 nm or less, about 300 nm or more and 3,000 nm or less, about 400 nm or more and 2,000 nm or less, or about 500 nm or more and 1,000 nm or less. Alternatively, the average particle diameter of the inorganic particles can be about 200 nm or more and 500 nm or less. When the average particle diameter of the inorganic particles is less than about 50 nm, as the specific surface area increases, a polymer binder for bonding between the inorganic particles is further required, which is disadvantageous in terms of electrical resistance. When the average particle diameter of the inorganic particles exceeds about 5,000 nm, the uniformity of the coating layer surface decreases, and damage to the porous polymer substrate or electrode during lamination may occur.

[0058] According to one embodiment of the present invention, the aspect ratio of the inorganic particles is about 1 to 2. For example, the aspect ratio of the inorganic particles may be about 1.1 to 1.9, about 1.2 to 1.8, about 1.3 to 1.7, or about 1.4 to 1.6. By adjusting the aspect ratio of the inorganic particles within the above range, the polymer binder can easily move through the voids between the inorganic particles, ultimately forming a porous coating layer including interstitial volumes through which lithium ions can move.

[0059] According to one embodiment of the present invention, the BET specific surface area of ​​the inorganic particles is about 5 m 2 / g or more 25m 2 For example, the BET specific surface area of ​​the inorganic particles is about 6 m / g or less. 2 / g or more 24m 2 / g or less, about 7m 2 / g or more 23m 2 / g or less, about 8m 2 / g or more 22m 2 / g or less, about 9m 2 / g or more 21m 2 / g or less, about 10m 2 / g or more 20m 2 / g or less, approximately 11m 2 / g or more 19m 2 / g or less, about 12m 2 / g or more 18m 2 / g or less, approximately 13m 2 / g or more 17m 2 / g or less, or about 14m 2 / g or more 26m 2 / g or less. By adjusting the BET specific surface area of ​​the inorganic particles within the above range, it is possible to adjust the movement of the polymer binder through the voids between the inorganic particles.

[0060] According to one embodiment of the present invention, the density of the inorganic particles is about 3 g / cm 3 More than 9g / cm 3 For example, the density of the inorganic particles is about 3.5 g / cm or less. 3 More than 8.5g / cm3 Below, about 4g / cm 3 More than 8g / cm 3 Below, about 4.5g / cm 3 More than 7.5g / cm 3 Below, about 5g / cm 3 More than 7g / cm 3 or less, or about 5.5 g / cm 3 More than 6.5g / cm 3 Alternatively, the density of the inorganic particles may be about 3 g / cm or less. 3 More than 4.5g / cm 3 By adjusting the density of the inorganic particles within the above range, the inorganic particles can be uniformly dispersed in the porous coating layer, and the thermal shrinkage of the porous polymer substrate can be reduced.

[0061] According to one embodiment of the present invention, the inorganic particles have a coating layer formed on their surfaces, the coating layer including a polymer having an amine group. For example, the inorganic particles and the coating layer may form a core-shell structure. Alternatively, the inorganic particles may be spherical, and the coating layer may completely surround the inorganic particles with a certain thickness.

[0062] According to one embodiment of the present invention, the amine group-containing polymer contains both a catechol group and an amine group. For example, the amine group-containing polymer may be one or more selected from dopamine and its derivatives. The amine group-containing polymer may physically or chemically bond with the inorganic particles via the catechol group to form a coating layer, exposing one or more amine groups on the surface of the coating layer. For example, the inorganic particles may contain one or more hydroxyl groups on their surfaces or be surface-treated to have hydroxyl groups, and the amine group-containing polymer may form a coating layer through hydrogen bonding with the hydroxyl groups via the catechol group, exposing the amine groups on the surface of the coating layer. The method of bonding the amine group-containing polymer with the inorganic particles is not limited thereto.

[0063] According to one embodiment of the present invention, the coating layer formed on the surface of the inorganic particles has a thickness of about 2 nm to 20 nm. For example, the coating layer may have a thickness of about 2 nm to 18 nm, about 4 nm to 16 nm, about 6 nm to 14 nm, or about 8 nm to 12 nm. Alternatively, the coating layer may have a thickness of about 2 nm to 5 nm. By adjusting the thickness of the coating layer within the above range, it is possible to prevent the coating layer from detaching from the inorganic particles under the operating conditions of the electrochemical device and to reduce thermal shrinkage of the separator by forming crosslinks with the polymer binder.

[0064] According to one embodiment of the present invention, the polymer binder crosslinks with the polymer containing amine groups and includes at least one selected from the group consisting of dextrin, polyetheretherketone (PEEK), polyethersulfone (PES), and polyacrylamide (PAAm). The polymer binder crosslinks with the polymer containing amine groups through a carboxyl group. Alternatively, the polymer containing amine groups is dopamine, and the polymer binder forms a hydrogen bond with a hydroxyl group of the dopamine through the amine group. The polymer binder has a high glass transition temperature (Tg) or decomposition temperature (Td), thereby imparting dimensional stability to the separator at high temperatures and forming a bond with the coating layer to prevent deformation of the porous coating layer.

[0065] According to one embodiment of the present invention, the polymer binder crosslinks with the amine group-containing polymer and includes a (co)polymer of a monomer selected from the group consisting of acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and carboxyethyl acrylate. The (co)polymer may include a carboxy group and may be crosslinked by forming an amide bond with the amine group exposed on the surface of the coating layer. The polymer binder forms a stable bond with one or more inorganic particles to form an interstitial volume while preventing deformation of the porous coating layer.

[0066] According to one embodiment of the present invention, the polymer binder may further include a fluorine-based polymer binder in addition to the polymer capable of crosslinking with the amine group-containing polymer. For example, the fluorine-based polymer binder may be a homopolymer of vinylidene fluoride, a copolymer of vinylidene fluoride and another copolymerizable monomer, or a mixture thereof.

[0067] According to one embodiment of the present invention, the polymer binder contains about 60 to 80 wt % of the polymer capable of crosslinking with the polymer containing amine groups, based on the total weight of the polymer binder. For example, about 66 to 75 wt % of the polymer binder may be crosslinked with the polymer containing amine groups, i.e., the coating layer formed on the surface of the inorganic particles. By adjusting the content of the polymer binder capable of crosslinking with the inorganic particles having the coating layer within the above range, a porous coating layer that is permeable to lithium ions and does not deform under high-temperature wet conditions can be formed.

[0068] According to one embodiment of the present invention, the porous coating layer contains the inorganic particles in an amount of about 90 wt% to 95 wt% based on the total weight of the porous coating layer. For example, the porous coating layer may contain the inorganic particles in an amount of about 90 wt% to 95 wt%, about 91 wt% to 92 wt%, or about 93 wt% to 94 wt%. Alternatively, the porous coating layer may contain the inorganic particles in an amount of about 92 wt% to 94 wt%. By adjusting the content of the inorganic particles within the above ranges, a separator having mechanical strength and thermal properties suitable for cylindrical batteries can be manufactured.

[0069] According to one embodiment of the present invention, the loading amount of the porous coating layer per unit area of ​​the porous polymer substrate in the separator is about 5.5 g / m 2 More than 8.0g / m 2 For example, the loading of the porous coating layer is about 5.7 g / m 2 More than 7.8g / m 2Below, approximately 5.9g / m 2 More than 7.6g / m 2 Below, approximately 6.1g / m 2 More than 7.4g / m 2 Below, about 6.3g / m 2 More than 7.2g / m 2 Below, about 6.5g / m 2 More than 7.0g / m 2 or less, or about 6.7 g / m 2 More than 6.8g / m 2 Alternatively, the loading of the porous coating layer may be about 5.6 g / m or less. 2 More than 6.5g / m 2 By adjusting the loading amount of the porous coating layer within the above range, the durability of the separator against the electrolyte can be ensured and thermal shrinkage in a high-temperature wet state can be reduced.

[0070] According to one embodiment of the present invention, the separator further includes a second polymer coating layer formed on the surface of the porous coating layer. For example, the second polymer coating layer may include a polymer containing an amine group. Alternatively, the polymer containing an amine group of the second polymer coating layer may include both a catechol group and an amine group. For example, the polymer containing an amine group may be one or more selected from dopamine and its derivatives.

[0071] According to one embodiment of the present invention, the second polymer coating layer is formed by applying a solution of a polymer containing an amine group to the surface of a separator including a porous polymer substrate and a porous coating layer, and then drying the applied solution. For example, the separator may be immersed in a solution of a polymer containing an amine group to obtain a separator having a second polymer coating layer containing the polymer.

[0072] For example, the polymer containing an amine group may be dopamine, and a separation membrane having a second polymer coating layer containing polydopamine can be obtained by immersing a separation membrane including a porous polymer substrate and a porous coating layer in a dopamine solution. The immersion time may be about 40 to 48 hours, and the loading amount of polydopamine in the second polymer coating layer may be about 0.0005 g / m. 2 More than 0.01g / m 2 By adjusting the amount of polydopamine contained in the second polymer coating layer within the above range, the heat shrinkage rate of the separator in a wet state can be reduced even under high temperature conditions.

[0073] According to one embodiment of the present invention, at least a portion of the polymer containing an amine group in the second polymer coating layer is crosslinked with the polymer binder in the porous coating layer. For example, the polymer binder in the porous coating layer may be thermally crosslinked via the amine group. The crosslinking may be achieved by applying a solution of the polymer containing an amine group to the surface of the porous coating layer and then drying, or by drying and then separately performing a heat treatment. The porous coating layer and the second polymer coating layer may form and maintain a stronger bond due to the crosslinking between the polymers, and the separator having this bond may exhibit a further reduced thermal shrinkage rate in a high-temperature wet state.

[0074] According to one embodiment of the present invention, the second polymer coating layer further includes dextrin. The dextrin imparts durability to the second polymer coating layer and improves dimensional stability of the separator including the second polymer coating layer. The dextrin uniformly disperses the amine group-containing polymer, thereby maintaining dimensional stability even when an external force is applied due to contraction or expansion of an electrode attached to or adjacent to the separator. Alternatively, the dextrin may be cyclodextrin, such as at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0075] According to one embodiment of the present invention, the second polymer coating layer contains the amine group-containing polymer and the dextrin in a weight ratio of about 1:500 to 1:1000. For example, the second polymer coating layer may contain polydopamine and dextrin in a weight ratio of about 1:600 ​​to 1:900 or about 1:700 to 1:800. By adjusting the contents of the polydopamine and the dextrin within the above ranges, it is possible to simultaneously achieve uniform dispersion of the polydopamine contained in the porous coating layer and a reduction in the thermal shrinkage rate of the separator in a wet state at high temperatures.

[0076] According to one embodiment of the present invention, the separator for an electrochemical device has an air permeability of about 50 s / 100 cc to about 150 s / 100 cc. For example, the air permeability of the separator may be about 60 s / 100 cc to about 140 s / 100 cc, about 70 s / 100 cc to about 130 s / 100 cc, about 80 s / 100 cc to about 120 s / 100 cc, or about 90 s / 100 cc to about 110 s / 100 cc. Alternatively, the air permeability of the separator may be about 100 s / 100 cc to about 120 s / 100 cc. When the air permeability of the separator is within the above range, the output, stability, and cycle characteristics of the electrochemical device can be ensured.

[0077] According to one embodiment of the present invention, the separator for an electrochemical device has a heat shrinkage of less than about 10%. For example, the separator has a heat shrinkage of less than about 10% in a wet state. For example, the heat shrinkage in a wet state is a dimensional change rate when the separator is immersed in an electrolyte and exposed to about 135°C for about 30 minutes.

[0078] According to one embodiment of the present invention, when a cell is fabricated using the separator for an electrochemical device, the cell has an electrical resistance of about 0.5 to 1.5 Ohms. For example, the electrical resistance of the cell may be about 0.6 to 1.4 Ohms, about 0.7 to 1.3 Ohms, about 0.8 to 1.2 Ohms, or about 0.9 to 1.1 Ohms. Alternatively, the electrical resistance of the cell may be about 0.6 to 0.8 Ohms.

[0079] Another embodiment of the present invention provides an electrochemical device including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the separator is the separator for an electrochemical device described above. The electrochemical device can be manufactured by inserting an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode into a case or pouch and sealing the case or pouch. Before sealing the case or pouch, an electrolyte can be injected to impregnate the electrode assembly with the electrolyte. The shape of the case or pouch is not limited. For example, the electrochemical device can be a cylindrical, prismatic, coin, or pouch-shaped lithium secondary battery.

[0080] According to one embodiment of the present invention, the positive electrode and the negative electrode are formed by coating at least one surface of a current collector with an electrode active material, which is then dried. The current collectors may be made of a conductive material that does not cause chemical changes in the electrochemical device. For example, the positive electrode current collector may be made of, but is not limited to, aluminum, nickel, titanium, calcined carbon, stainless steel, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. For example, the negative electrode current collector may be made of, but is not limited to, copper, nickel, titanium, calcined carbon, stainless steel, or copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like. The current collectors may be in various forms, such as a metal sheet, film, foil, net, porous material, or foam.

[0081] According to an embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer containing 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 includes layered compounds such as lithium manganese composite oxides (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and compounds substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x O4 (where x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), Ni-site type lithium nickel oxides represented by this; chemical formula LiMn 1-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1), or lithium manganese composite oxides represented by Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a part of Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; one or a mixture of two or more of Fe2(MoO4)3 may be included.

[0082] According to an embodiment of the present invention, the negative electrode includes a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode uses, as the negative electrode active material, carbon such as lithium metal oxide, graphitized carbon, graphite-based carbon; LixFe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Si, SiO x [[ID=二十]]](0 < x < 2), silicon-based materials such as SiC, Si alloys; Sn x Me 1-x Me’ y O z(Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8), etc. metal composite oxides; lithium metal; lithium alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; one or more mixtures selected from titanium oxides may be included.

[0083] According to one embodiment of the present invention, the conductive material is any 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 of these conductive materials. The carbon nanotube has a cylindrical shape with a nanosize diameter of a graphite sheet and has a sp 2 bonding structure, and exhibits conductor or semiconductor characteristics depending on the angle and structure of the graphite sheet being wound. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), and multi-walled carbon nanotubes (MWCNT) according to the number of bonding layers forming the wall, and these carbon nanotubes can be appropriately selected according to the use of the dispersion liquid. For example, the conductive material may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, ketjen black, channel black, furnace black, lamp black, 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.

[0084] According to one embodiment of the present invention, the binder resin may be a binder resin that is commonly used in electrodes of electrochemical devices. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples of suitable cellulose acetates include, but are not limited to, cyanoethyl acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxyl methyl cellulose.

[0085] According to one embodiment of the present invention, the electrolyte is + B- A salt having the structure: + Li + , Na + , K. + or a combination thereof, - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - or a salt containing an anion such as the above, or an ion consisting of a combination thereof, is dissolved or dissociated in an organic solvent consisting of 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.

[0086] For example, the electrolyte may contain a solvent in which the weight ratio of ethylene carbonate (EC) / ethylmethyl carbonate (EMC) is 3 / 7, or a solvent in which the weight ratio of ethylene carbonate (EC) / ethylmethyl carbonate (EMC) / dimethyl carbonate (DMC) is 20 / 5 / 75, thereby maximizing the dimensional stability of the separator according to the above examples.

[0087] According to one embodiment of the present invention, the electrochemical device including the electrode assembly is a lithium secondary battery. The separator for an electrochemical device including the electrode assembly according to the present invention may also be applied to a sodium secondary battery manufactured using sodium ions as a positive electrode active material.

[0088] Furthermore, unlike the above-described lithium secondary battery, the lithium secondary battery according to another embodiment of the present invention may be an all-solid-state battery.

[0089] The battery can be used as a unit cell, a battery module including the unit cell, a battery pack including the battery module, or a device including the battery pack as a power source. Examples of such devices include, but are not limited to, small devices such as computers, mobile phones, and power tools; electric vehicles powered by electric motors, including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters; electric golf carts; and energy storage systems.

[0090] The present invention will be described in more detail below with reference to examples and experimental examples. The following examples and comparative experimental examples are provided to illustrate the present invention, and the examples according to the present invention may be modified in various different forms, and the present invention is not limited to the following examples and experimental examples.

[0091] Example 1 [Preparation of inorganic particles having a coating layer formed thereon] 30 g of Al2O3 (particle size: 400 nm) as inorganic particles and 2 g of dopamine as a polymer containing amine groups were mixed with 1000 mL of a basic aqueous solution (Tris buffer, pH 8.5), and the mixture was stored at 20°C for 4 hours. After that, the mixture was repeatedly ultrasonically cleaned with secondary distilled water and completely dried at 50°C to obtain inorganic particles with a polydopamine coating layer (thickness: 2 nm) formed.

[0092] [Preparation of coating slurry] At room temperature (25°C), 1.5 g of polyacrylate as a polymer binder, 30 g of inorganic particles with the polydopamine coating layer formed thereon, and 0.2 g of a silicon-based surfactant as an additive were added to 50 mL of water, and the mixture was stirred for 60 minutes using a shaker to prepare a coating slurry in which the polymer binder and inorganic particles were dispersed.

[0093] [Preparation of porous polymer substrate] The porous polymer substrate was (MI: 0.2 g / 10 min, T m A polyethylene film having a thickness of 9 μm and a temperature of 135°C, porosity of 45%, and average pore size of 45 nm was used.

[0094] [Production of separation membrane] The coating slurry was coated on both sides of a polyethylene film using a bar coater, with each coating having a thickness of 2 μm and a loading of 6.3 g / m 2 A coating layer of the formula was formed.

[0095] The polyethylene film with the coating layer was subjected to a low-temperature airflow of 50°C to remove the dispersion medium, which was repeated five times. The film was then dried at 100°C for 10 minutes to crosslink the polydopamine and polyacrylic acid, producing a separator with a total thickness of 13 μm.

[0096] Example 2 Polymaleic acid was used as the polymer binder, and the loading of the porous coating layer was 6.0 g / m 2A separation membrane was produced in the same manner as in Example 1, except that:

[0097] Example 3 Dextrin was used as the polymer binder, and the loading of the porous coating layer was 6.4 g / m 2 A separation membrane was prepared in the same manner as in Example 1, except that:

[0098] Example 4 PAAm was used as the polymer binder, and the loading of the porous coating layer was 5.7 g / m 2 A separation membrane was prepared in the same manner as in Example 1, except that:

[0099] Example 5 A separator was prepared in the same manner as in Example 1, except that dextrin and PVdF-HFP were used as the polymer binder in a weight ratio of 3:1.

[0100] Example 6 Dopamine 2 mg / mL and dextrin 50 mg / mL were added to a 20 mM basic buffer (Tris-HCl buffer) at room temperature (25°C), with the amounts adjusted so that the final ratio of dopamine to dextrin was 1:1000. Then, the lid of the Petri dish was partially opened to prepare a dopamine and dextrin solution with a dissolved oxygen content of 9 ppm and a pH of 8.

[0101] The separator prepared in Example 1 was immersed in the solution for 48 hours and then dried at 60° C. for 12 hours to prepare a separator having a second polymer coating layer with a thickness of 0.5 μm.

[0102] Comparative Example 1 The separator for an electrochemical device of Example 1 was prepared in the same manner as in Example 1, except that the inorganic particles and dopamine were adjusted to 30 g and 0.5 g, respectively, during the preparation of the coating slurry (coating layer thickness: 1 nm).

[0103] Comparative Example 2 A separator for an electrochemical device was prepared in the same manner as in Example 1, except that polyurethane was used as the polymer binder.

[0104] Comparative Example 3 A separator for an electrochemical device was prepared in the same manner as in Example 1, except that inorganic particles without a coating layer were used.

[0105] Comparative Example 4 A separator for an electrochemical device of Example 2 was prepared in the same manner as in Example 2, except that inorganic particles without a coating layer were used.

[0106] Comparative Example 5 A separator for an electrochemical device of Example 2 was prepared in the same manner as in Comparative Example 2, except that inorganic particles without a coating layer were used.

[0107] Comparative Example 6 A separator for an electrochemical device of Example 5 was prepared in the same manner as in Example 5, except that dextrin and PVdF-HFP were used as the polymer binder in a weight ratio of 1:1.

[0108] Experimental example: Confirming the physical properties of separation membranes The physical properties of the separation membranes produced according to the Examples and Comparative Examples are shown in Tables 1 and 2, respectively.

[0109] [Confirmation of improvement in heat shrinkage rate in wet state] The separators of the examples and comparative examples were prepared as test pieces of 5 cm x 5 cm, and inserted into aluminum pouches of 7 cm x 10 cm, respectively. 1 g of electrolyte was poured into the pouches, and the pouches were sealed.

[0110] The electrolyte used was a solvent in which ethylene carbonate (EC) / ethyl methyl carbonate (EMC) was mixed in a weight ratio of 3 / 7, and contained 3 mol of vinylene carbonate (VC), 1.5 mol of propane sultone (PS), 1 mol of ethylene sulfate (ESa), and 1 mol of lithium salt LiPF6 as additives.

[0111] The sealed pouch was stored in a convection oven at 135°C for 30 minutes, and then disassembled to obtain a separator membrane. The thermal shrinkage in the TD direction was calculated according to [(initial specimen length - length after storage at 135°C for 0.5 hours) / (initial specimen length)] x 100 (%).

[0112] [Table 1]

[0113] [Table 2]

Claims

1. The porous polymer substrate includes a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer includes inorganic particles and a polymer binder; The inorganic particles have a polymer coating layer containing an amine group formed on the surface of the inorganic particles, At least a portion of the polymer binder is crosslinked with the polymer containing an amine group.

2. 2. The separator for an electrochemical device according to claim 1, wherein the polymer containing an amine group is dopamine or a derivative thereof.

3. 2. The separator for an electrochemical device according to claim 1, wherein the polymer coating layer has a thickness of 2 nm to 20 nm.

4. The polymer binder is 2. The separator for an electrochemical device according to claim 1, comprising at least one selected from the group consisting of dextrin, polyether ether ketone, polyether sulfone, and polyacrylamide.

5. The polymer binder is 2. The separator for an electrochemical device according to claim 1, which comprises a (co)polymer of a monomer selected from the group consisting of acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and carboxyethyl acrylate.

6. 2. The separator for an electrochemical device according to claim 1, wherein 60 to 80% by weight of the polymer binder is crosslinked with the polymer containing an amine group.

7. The loading amount of the porous coating layer per unit area of ​​the porous polymer substrate is 5.5 g / m ２ ~8g / m ２ The separator for electrochemical elements according to claim 1, wherein

8. The porous coating layer comprises:

2. The separator for an electrochemical device according to claim 1, wherein the inorganic particles are contained in an amount of 90 to 95 wt % based on the total weight of the porous coating layer.

9. The porous coating layer further includes a second polymer coating layer formed on the surface of the porous coating layer, The second polymeric coating layer comprises: The separator for an electrochemical device according to claim 1 , comprising the polymer containing an amine group.

10. 10. The separator for an electrochemical device according to claim 9, wherein at least a portion of the polymer containing an amine group in the second polymer coating layer is crosslinked with the polymer binder in the porous coating layer.

11. The separator for an electrochemical device according to claim 9, wherein the second polymer coating layer further comprises dextrin.

12. An electrochemical device comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, An electrochemical device, wherein the separator is the separator for electrochemical devices according to claim 1 .

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