Separation Membrane for Electrochemical Element and Electrochemical Element Containing the Same

Abstract

The present invention 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 first polymer binder and the inorganic particles each having a different ligand introduced therein.

Description

[Technical field]

[0001] This application claims priority to Korean Patent Application No. 10-2023-0044174 filed with the Korean Intellectual Property Office on April 4, 2023, the contents of which are incorporated herein by reference in their entirety.

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

[0003] 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 and voltage, long cycle life, and can be used in a variety of fields.

[0004] 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 in a case together with an electrolyte. The positive electrode may provide lithium ions, and the lithium ions may move to the negative electrode through a separator made of a porous material. The negative electrode may use a carbon-based active material that has an electrochemical reaction potential close to that of lithium metal and is capable of inserting and extracting lithium ions. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a separator for an electrochemical device that uses a positive electrode active material containing a transition metal such as manganese, and that is capable of adsorbing transition metal ions eluted from a positive electrode. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a separator for an electrochemical device, comprising a porous polymer substrate, a first polymer binder, and inorganic particles, and a porous coating layer formed on at least one surface of the porous polymer substrate, wherein different ligands are introduced into the first polymer binder and the inorganic particles, respectively, and the first polymer binder and the inorganic particles form coordinate bonds with a single metal ion.

[0007] The first polymer binder and the inorganic particles may each independently be chemically bonded with one or more ligands selected from a first ligand having one denticity and a second ligand having two or more denticities.

[0008] The first ligand may be one or more selected from the group consisting of imidazole, pyrazole, triazole, tetrazole, indazole, benzimidazole, azaindole, purine, and derivatives thereof.

[0009] The second ligand may be one or more selected from the group consisting of nitrilotriacetic acid, iminodiacetic acid, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, and derivatives thereof.

[0010] The inorganic particles may have the second ligand chemically bonded to the surface thereof.

[0011] The inorganic particles may be included in an amount of 40 to 80 wt % based on the total weight of the porous coating layer.

[0012] The porous coating layer may further comprise a second polymeric binder, and the content of the first polymeric binder may be greater than or equal to the content of the second polymeric binder.

[0013] Another aspect of the present invention provides an electrochemical device including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, the separator being a separator for an electrochemical device having the above-described characteristics.

[0014] The electrochemical device may be a lithium secondary battery.

[0015] The metal ions may be generated during a charge / discharge process of the electrochemical device.

[0016] The metal ions may be transition metal ions derived from the positive electrode.

[0017] Another aspect of the present invention relates to an electric device including an electrochemical device having the above-mentioned characteristics.

[0018] Another aspect of the present invention relates to a method for manufacturing a separator for an electrochemical device, the method comprising forming a porous coating layer including a first polymer binder and inorganic particles on at least one surface of a porous polymer substrate, wherein different ligands are introduced into the first polymer binder and the inorganic particles.

[0019] The step of forming the porous coating layer may include preparing a coating slurry including the first polymer binder, the inorganic particles, and a dispersion medium, and applying the coating slurry to at least one surface of the porous polymer substrate.

[0020] The coating slurry may further include a second polymeric binder.

[0021] The step of forming the porous coating layer may further include subjecting at least one surface of the porous polymeric substrate to a corona discharge treatment before applying the coating slurry to at least one surface of the porous polymeric substrate.

[0022] The step of forming the porous coating layer may include drying the coating slurry applied to at least one surface of the porous polymer substrate to evaporate the dispersion medium. Effect of the Invention

[0023] The separator for an electrochemical device according to the present invention can adsorb metal ions generated during charging and discharging, thereby preventing a decrease in performance due to the deposition of impurities in the electrochemical device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, each component 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 to the following content.

[0025] As used herein, the term "comprising" is used in listing materials, compositions, devices, and methods useful in the present invention, without limiting the listed examples.

[0026] As used in this specification, the terms "about," "approximately," and "substantially" are used to mean a range or approximate value of a numerical value or degree, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly taking advantage of the disclosure in which precise numerical values ​​or absolute numerical values ​​are mentioned, which are provided to aid in the understanding of the present invention.

[0027] As used herein, "electrochemical device" may refer to a primary battery, a secondary battery, a supercapacitor, and the like.

[0028] The positive electrode active material may include lithium and various metal or transition metal elements. For example, nickel can improve the capacity of an electrochemical element, cobalt can improve the capacity and cycle stability of an electrochemical element, manganese can improve the stability of an electrochemical element, and aluminum can improve the output characteristics of an electrochemical element. In recent years, research has been conducted to develop electrochemical elements having higher energy density and stability by utilizing these transition metals. For example, lithium manganese-based positive electrode active materials containing manganese have attracted attention because they have better thermal stability than active materials containing nickel and are more price competitive than active materials containing nickel or cobalt.

[0029] In an electrochemical device using a positive electrode active material containing a transition metal such as manganese, transition metal ions may be eluted from the positive electrode during charging and discharging. The eluted transition metal ions may migrate to the negative electrode and precipitate as impurities on the surface of the negative electrode, or may form a non-uniform film, causing capacity degradation of the electrochemical device.

[0030] Therefore, there is a need for a separator for use in an electrochemical device including a positive electrode active material containing a transition metal such as manganese, which can capture transition metal ions eluted from the positive electrode and prevent them from migrating to the negative electrode, thereby preventing deterioration of the negative electrode and the electrochemical device including the same.

[0031] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate, a porous coating layer including a first polymer binder and inorganic particles and formed on at least one surface of the porous polymer substrate, wherein different ligands are introduced into the first polymer binder and the inorganic particles, respectively, and the first polymer binder and the inorganic particles form coordinate bonds with a single metal ion.

[0032] The porous polymer substrate may be a porous film having a plurality of pores formed therein, and may electrically insulate the positive and negative electrodes to prevent short circuits. For example, when the electrochemical device is a lithium secondary battery, the porous polymer substrate may be an ion-conductive barrier that blocks electrical contact between the positive and negative electrodes while allowing lithium ions to pass through. At least a portion of the pores may form a three-dimensional network that communicates with the surface and the interior of the porous polymer substrate, and a fluid may pass through the porous polymer substrate through the pores.

[0033] The porous polymer substrate may be made of a material that is physically and chemically stable against the electrolyte, which is an organic solvent. For example, the porous polymer substrate may include, but is 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. Preferably, a polyolefin resin may be used. Polyolefin resins can be processed to a relatively thin thickness and are easy to apply a coating slurry, making them suitable for manufacturing electrochemical devices with higher energy density.

[0034] The porous polymer substrate may have a single layer or multi-layer structure. The porous polymer substrate may include two or more polymer resin layers having different melting points (Tm) and may provide a shutdown function during high temperature runaway of the battery. For example, the porous polymer substrate may include a polypropylene layer having a relatively high melting point and a polyethylene layer having a relatively low melting point. Preferably, the porous polymer substrate may have a three-layer structure in which polypropylene, polyethylene, and polypropylene are laminated in this order. The polyethylene layer may shut down the pores as it melts as the temperature of the battery rises above a predetermined temperature, thereby preventing thermal runaway of the battery.

[0035] The thickness of the porous polymer substrate may be about 1 μm to 100 μm. For example, the thickness of the porous polymer substrate may be about 10 μm to 90 μm, 20 μm to 80 μm, 30 μm to 70 μm, or 40 μm to 60 μm. For example, the thickness of the polymer substrate may be about 1 μm to 30 μm. Also, the thickness of the polymer substrate may be 5 μm to 15 μm, or 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 while electrically insulating the positive and negative electrodes, and the amount of active material contained in the electrochemical device can be increased.

[0036] The porous polymer substrate may include pores having an average diameter of about 0.01 μm to 1 μm, for example, round, circular, elliptical, etc. For example, the size of the pores included in the porous polymer substrate may be about 0.01 μm to 0.09 μm, 0.02 μm to 0.08 μm, 0.03 μm to 0.07 μm, or 0.04 μm to 0.06 μm. According to one embodiment, the size of the pores may be about 0.02 μm to 0.06 μm. By adjusting the size of the pores of the porous polymer substrate within the above range, the air permeability and ion conductivity of the entire separation membrane to be manufactured can be adjusted.

[0037] The porous polymer substrate may have an air permeability of about 10s / 100cc to 100s / 100cc. For example, the air permeability of the porous polymer substrate may be about 10s / 100cc to 90s / 100cc, 20s / 100cc to 80s / 100cc, 30s / 100cc to 70s / 100cc, or 40s / 100cc to 60s / 100cc. Preferably, the air permeability of the porous polymer substrate may be 50s / 100cc to 70s / 100cc. When the air permeability of the porous polymer substrate is within the above range, the air permeability of the separator to be manufactured can be provided within a range suitable for ensuring the output and cycle characteristics of the electrochemical device.

[0038] The air permeability (s / 100cc) refers to the time (seconds) required for 100cc of air to pass through a porous polymeric substrate or a separator with a predetermined 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 of water pressure in 1 square inch (or 6.54 cm 2 For example, the Asahi Seiko EG01-55-1MR instrument can be used to measure the time it takes for 100 cc of air to pass through a 1 inch square sample at room temperature under a constant pressure of 4.8 inches of water.

[0039] The porous polymer substrate may have a porosity of about 10 vol% to 60 vol%. For example, the porosity of the porous polymer substrate may be about 15 vol% to 55 vol%, 20 vol% to 50 vol%, 25 vol% to 45 vol%, or 30 vol% to 40 vol%. For example, the porosity of the porous polymer substrate may be about 30 vol% to 50 vol%. When the porosity of the porous polymer substrate is within the above range, the ion conductivity of the separator produced can be provided within a range suitable for ensuring the output and cycle characteristics of the electrochemical device.

[0040] The porosity means the volume ratio of the pores to the total volume of the porous polymer substrate. The porosity can be measured by a method known in the art. For example, the porosity can be measured by the Brunauer Emmett Teller (BET) measurement method using nitrogen gas adsorption, capillary flow porometer, water or mercury penetration method.

[0041] The porous coating layer may be formed on at least one surface of the porous polymer substrate and may include a first polymer binder and inorganic particles. Different ligands may be introduced into the first polymer binder and the inorganic particles. The expression that the ligand is "introduced" into the first polymer binder and the inorganic particles means that the ligand is chemically bonded to the polymer binder and / or the inorganic particles. The method of chemically bonding the ligand is not limited as long as the ligand maintains its ability to coordinate with metal ions, and any method known in the art may be used. The first polymer binder may be one in which the ligand is chemically bonded through a predetermined portion of a repeating unit. The inorganic particles may be one that is chemically bonded to the ligand through a functional group exposed on the particle surface, and the inorganic particles may be one that is chemically bonded to the ligand through the functional group after the surface of the inorganic particles is modified with a predetermined functional group.

[0042] The first polymer binder and the inorganic particles each contain different ligands and can form a coordinate bond with a metal ion, and can form a coordinate bond with a single metal ion. Specifically, the first polymer binder and the inorganic particles can simultaneously form a coordinate bond with a single metal ion. For example, one first polymer binder and one or more inorganic particles can simultaneously form a coordinate bond with one metal ion. A porous coating layer capable of forming a coordinate bond with a single metal ion can easily form a complex with the metal ion and can maintain a stable structure even after the complex is formed.

[0043] The first polymer binder and the inorganic particles may each independently be chemically bonded with one or more ligands selected from a first ligand having one coordination site and a second ligand having two or more coordination sites. For example, a first ligand having one coordination site and a second ligand having two coordination sites may simultaneously form a coordinate bond with a single metal ion. The first ligand and the second ligand may each independently be chemically bonded with one or more of the first polymer binder and the inorganic particles. Preferably, the first polymer binder may be chemically bonded with the first ligand, and the inorganic particles may be chemically bonded with the second ligand, or vice versa.

[0044] The first ligand may be at least one selected from the group consisting of imidazole, pyrazole, triazole, tetrazole, indazole, benzimidazole, azaindole, purine, and derivatives thereof. The first ligand includes an aromatic heterocycle and can form a coordinate bond with a metal ion at one site. The derivative is not limited in type as long as it can form a coordinate bond with a metal ion and can form a chemical bond with the first polymer binder or inorganic particles. Preferably, the first ligand may be imidazole or a derivative thereof.

[0045] The second ligand may be at least one selected from the group consisting of nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), ethylenediaminetetraacetic acid (EDTA), 1,2-cyclohexanediamine-N,N,N',N'-tetraacetic acid, and derivatives thereof. The second ligand may be acetic acid, which contains two or more carboxyl groups and can form coordinate bonds with metal ions at two or more positions. The derivative is not limited in type as long as it can form coordinate bonds with metal ions and can form chemical bonds with the first polymer binder or inorganic particles. Preferably, the second ligand may be selected from nitrilotriacetic acid, iminodiacetic acid, or derivatives thereof.

[0046] Preferably, the first polymer binder may be a binder to which the first ligand is chemically bonded, and the inorganic particles may be a binder to which the second ligand is chemically bonded. The second ligand may be less stable in an electrochemical device than the first ligand. The second ligand may cause a side reaction with an electrolyte in an electrochemical device. Therefore, it may be more advantageous for maintaining the metal ion adsorption ability to have the second ligand bonded to the surface of the inorganic particles than to the first polymer binder, which may be dissolved or swollen by the electrolyte.

[0047] According to a specific example, the first polymer binder may contain nitrilotriacetic acid as a ligand, and the inorganic particles may contain imidazole as a ligand. The metal ions may be contained in an electrochemical element and may be generated during the charge and discharge process of the electrochemical element. Specifically, the metal ions may be transition metal ions derived from the positive electrode. For example, the metal ions may be divalent transition metal ions such as manganese, nickel, and cobalt ions eluted from the positive electrode active material. The divalent ions may be coordinated with one nitrilotriacetic acid and two imidazoles, with six dentates per ion. The metal ions are coordinated with the first polymer binder and the inorganic particles to form a complex, which may suppress migration to the negative electrode and side reactions with the electrolyte.

[0048] The porous coating layer may further include a second polymer binder. The second polymer binder does not include a ligand. The first polymer binder and the second polymer binder may bind the inorganic particles included in the porous coating layer and provide adhesive strength to the porous coating layer. The first polymer binder may include the above-mentioned ligand and be used for adsorbing metal ions, and may have a lower adhesive strength than the second polymer binder. The second polymer binder may provide the safety of the separator by allowing the porous coating layer to maintain stable adhesion to the porous polymer substrate. Preferably, the content of the first polymer binder may be greater than or equal to the content of the second polymer binder. Specifically, the first polymer binder and the second polymer binder may be included in a weight ratio of about 7:3 to 5:5. By adjusting the content of the polymer binder within the above range, a porous coating layer having metal ion adsorption performance and stable adhesion to the porous substrate may be formed.

[0049] The first and second polymer binders may be selected from an acrylic polymer binder, a fluorine-based polymer binder, or a combination thereof. Preferably, the first polymer binder is an acrylic polymer, and the second polymer binder is a fluorine-based polymer binder.

[0050] The acrylic polymer binder is, for example, (meth)acrylic acid, (meth)acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-ethylhexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, n-ethylhexyl methacrylate, 2-ethylhexyl The monomer may include one or more repeating units selected from the group consisting of methacrylate, hydroxyethyl methacrylate, (meth)acrylonitrile butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, ethyl (meth)acrylate, methyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, n-oxyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, and pentafluorophenyl acrylate.

[0051] For example, the acrylic polymer binder may include one or more selected from the group consisting of polyacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, ethylhexyl acrylate, methyl methacrylate, styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, and acrylonitrile-butadiene-styrene rubber.

[0052] The fluorine-based polymer binder may be a polyvinylidene fluoride-based polymer binder. For example, the fluorine-based polymer binder may be at least one selected from the group consisting of polyvinylidene fluoride, polyhexafluoropropylene, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyvinylidene fluoride-trichloroethylene (PVDF-TCE), and polyvinylidene fluoride-chlorotrifluoroethylene (PVDF-CTFE), and more specifically, may be a copolymer containing polyvinylidene fluoride.

[0053] At least one of the first polymer binder and the second polymer binder may be particulate. For example, the polymer binder may be spherical or elliptical, but is not limited thereto. The polymer binder may have an average particle size (D50) of 100 nm to 2000 nm. Specifically, the polymer binder may have an average particle size (D50) of 200 nm to 1000 nm, or 300 nm to 800 nm. By controlling the particle size of the polymer binder particles within the above range, it is possible to simultaneously ensure the migration path of lithium ions and the adhesive strength of the porous coating layer to the porous substrate.

[0054] The weight average molecular weight (Mw) of the first polymer binder and the second polymer binder may be about 40,000 to 500,000. For example, the weight average molecular weight of the polymer binder may be about 50,000 to 450,000, 100,000 to 400,000, 150,000 to 350,000, or 200,000 to 300,000. For example, the weight average molecular weight of the first polymer binder may be about 40,000 to 100,000, and the weight average molecular weight of the second polymer binder may be about 40,000 to 200,000. By controlling the weight average molecular weight of the polymer binder within the above range, the polymer binder is uniformly dispersed, and a porous coating layer that simultaneously realizes the adsorption ability for metal ions and the adhesion ability to the porous polymer substrate can be formed.

[0055] The weight average molecular weight of the polymer binder in the present invention can be measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies). For example, the weight average molecular weight can be measured using an Agilent High Temperature RI detector under the conditions of a PL Olexis (Polymer Laboratories) column (column temperature 160° C.) with trichlorobenzene (TCB) as a solvent, a sample concentration of 1.0 mg / mL, a flow rate of 1.0 mL / min, and an injection amount of 200 μl (corrected with a cubic function, standard: polystyrene).

[0056] The porous coating layer may include the inorganic particles in an amount of about 40 wt% to 80 wt% based on the total weight of the porous coating layer. For example, the content of the inorganic particles in the total weight of the porous coating layer may be about 45 wt% to 75 wt%, 50 wt% to 70 wt%, or 55 wt% to 65 wt%. For example, the content of the inorganic particles may be about 60 wt% to 80 wt%. The porous coating layer including the inorganic particles in the above range may reduce the thermal shrinkage of the porous polymer substrate and prevent the occurrence of short circuits of the electrodes due to the shrinkage of the separator.

[0057] The inorganic particles may be electrochemically stable. The inorganic particles may be within the operating voltage range of the electrochemical device (e.g., Li / Li + There are no particular limitations on the dielectric constant as long as no oxidation and / or reduction reaction occurs at a voltage of 0 to 5 V relative to the reference voltage. In particular, when inorganic particles having a high dielectric constant are used as the inorganic particles, the inorganic particles can contribute to an increase in the degree of dissociation of an electrolyte salt, for example, a lithium salt, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte. For the reasons described above, the inorganic particles may include inorganic particles having a high dielectric constant, with a dielectric constant of 5 or more, preferably 10 or more. Non-limiting examples of inorganic particles having a dielectric constant of 5 or more include BaTiO3 , Pb(Zr,Ti)O 3 (PZT), b 1-x La x Zr 1-y Ti y O 3 (PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3 )O 3 -PbTiO 3 (PMN-PT), hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CEO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 , Al(OH) 3 , SiC, AlOOH, TiO 2 , or a mixture thereof.

[0058] In addition, inorganic particles having a lithium ion transfer ability, i.e., inorganic particles containing lithium element but having a function of transferring lithium ions without storing lithium, can be used as the inorganic particles. Non-limiting examples of inorganic particles having a lithium ion transfer ability include lithium phosphate (Li 3 PO 4 ), lithium titanium phosphate (Li x Ti y (PO 4 ) 3 , 0 <x<2、0<y<3)、リチウムアルミニウムチタンホスフェート(Li x Al y Ti z (PO 4 ) 3 , 0 <x<2、0<y<1、0<z<3)、14Li 2 O-9Al 2 O 3 -38TiO 2 -39P 2 O 5 Such as (LiAlTiP) xO y System glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO 3 , 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25 P 0.75 S 4 such as lithium germanium thiophosphate (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), Li 3 N such as lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), Li 3 PO 4 -Li 2 S-SiS 2 such as SiS 2 system glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), LiI-Li 2 S-P 2 S 5 such as P 2 S 5 system glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7), or mixtures thereof, etc.

[0059] Also, 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 inorganic particles having flame retardancy include Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , SrTiO 3 , SnO 2 , CeO 2 , MgO, Mg(OH) 2 , NiO, CaO, ZnO, Zn2 SnO 4 , ZnSnO 3 , ZnSn(OH) 6 , ZrO 2 , Y 2 O 3 , SiO 2 , Al 2 O 3 , AlOOH, Al(OH) 3 , SiC, TiO 2 , H 3 BO 3 , HBO 2 and mixtures thereof.

[0060] The average particle size (D50) of the inorganic particles may be about 10 nm to 10,000 nm. For example, the average particle size (D50) of the inorganic particles may be about 100 nm to 9,000 nm, 1,000 nm to 8,000 nm, 2,000 nm to 7,000 nm, 3,000 nm to 6,000 nm, or 4,000 nm to 5,000 nm. For example, the average particle size of the inorganic particles may be about 100 nm to 700 nm. If the average particle size of the inorganic particles is less than 10 nm, the specific surface area increases, and a polymer binder is further required for bonding between the inorganic particles, which is disadvantageous in terms of electrical resistance. If the average particle size of the inorganic particles exceeds 10,000 nm, the uniformity of the coating layer surface decreases, which may cause damage to the porous polymer substrate or the electrode during lamination.

[0061] The porous coating layer may be formed by coating one surface of the porous polymer substrate with a coating slurry including the first polymer binder, the inorganic particles, and a dispersion medium. The coating slurry may further include a second polymer binder. For example, the separator may be manufactured by applying the coating slurry to at least one surface of the porous polymer substrate and then drying the coating slurry to remove the dispersion medium. The porous coating layer may have a porous structure including an interstitial volume in which the inorganic particles are connected by the first polymer binder or the first polymer binder and the second polymer binder. The porous coating layer is adhered to the porous polymer substrate while allowing lithium ions to pass therethrough, and may prevent thermal shrinkage of the porous polymer substrate.

[0062] The coating slurry may include a dispersion medium, and may dissolve or disperse at least a portion of the polymer binder to disperse the inorganic particles. The coating slurry may be used in which the inorganic particles are uniformly dispersed by adjusting the type and content of the dispersion medium. For example, the dispersion medium may be 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 may be formed.

[0063] The coating slurry may have a viscosity of about 100 cps to 1,000 cps. For example, the viscosity of the coating slurry may be about 200 cps to 900 cps, 300 cps to 800 cps, 400 cps to 700 cps, or 500 cps to 600 cps. For example, the viscosity of the coating slurry may be about 300 cps to 800 cps. If the viscosity of the coating slurry exceeds 1,000 cps, a slurry with a very large particle size (D99) (D99 to 100 μm) is formed, making it difficult to manufacture a separation membrane by continuous coating on a porous polymer substrate, and productivity cannot be ensured.

[0064] The coating slurry may further include additives such as a dispersant, a surfactant, an antifoaming agent, a flame retardant, and a wetting agent 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 above-mentioned types of dispersants may be used to improve the stability of the coating slurry and ensure the uniformity of the porous coating layer formed from the coating slurry.

[0065] The additive may be included in an amount of 0 to 5 wt % based on the total weight of the coating slurry. Specifically, the additive may be included in an amount of 0.01 to 4 wt %, 0.1 to 3 wt %, or 1 to 2 wt %. Preferably, 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 inorganic particles included in the coating slurry can be achieved.

[0066] The dispersion medium contained in the coating slurry may be removed by drying or heating after the formation of the porous coating layer. For example, the porous coating layer may contain about 5 ppm or less of the dispersion medium. Preferably, the porous coating layer may be composed of a first polymer binder and inorganic particles, or a first polymer binder, a second polymer binder and inorganic particles. In the process of removing the dispersion medium, a plurality of pores may be formed on the surface and inside of the porous coating layer. The pores may include interstitial volumes formed between inorganic particles, and may have a structure that forms a three-dimensional network to allow fluid to pass through.

[0067] The thickness of the porous coating layer may be about 1 μm to 15 μm. For example, the thickness of the porous coating layer may be about 2 μm to 14 μm, 3 μm to 13 μm, 4 μm to 12 μm, 5 μm to 11 μm, 6 μm to 10 μm, or 7 μm to 9 μm. For example, the thickness of the porous coating layer may be about 1 μm to 5 μm. By adjusting the thickness of the porous coating layer within the above range, the shrinkage of the porous polymer substrate can be minimized and stable adhesion to the porous polymer substrate can be achieved.

[0068] The separator for an electrochemical device may have an air permeability of about 50s / 100cc to 150s / 100cc. For example, the air permeability of the separator may be 60s / 100cc to 140s / 100cc, 70s / 100cc to 130s / 100cc, 80s / 100cc to 120s / 100cc, or 90s / 100cc to 110s / 100cc. For example, the air permeability of the separator may be about 100s / 100cc to 120s / 100cc. 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.

[0069] 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, the separator being the separator for an electrochemical device of the embodiment described above. The electrochemical device may 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 may 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 may be a cylindrical, square, coin, or pouch type lithium secondary battery.

[0070] The positive electrode and the negative electrode may be coated by applying and drying an electrode active material to at least one surface of each current collector. The current collector may be a material having electrical conductivity without causing a chemical change in the electrochemical element. For example, the positive electrode current collector may be, 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, 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 collector may be in various forms such as a metal sheet, a film, a foil, a net, a porous body, a foam, or the like.

[0071] The positive electrode includes a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector, the positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin. The positive electrode active material is a lithium manganese composite oxide (LiMn 2 O 4 , LiMnO 2 etc.), lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ) 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), LiMnO 3 , LiMn 2 O 3 , LiMnO 2 Lithium manganese oxides such as lithium copper oxide (Li 2 CuO 2 );LiV 3 O 8 , LiV 3 O 4 , V 2 O 5 , Cu 2 V 2 O 7 Vanadium oxides such as LiNi 1-x M x O 2 (wherein M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x=0.01 to 0.3); 1-x M x O 2 (wherein M=Co, Ni, Fe, Cr, Zn or Ta, and x=0.01 to 0.1) or Li 2 Mn 3 MO 8 Lithium manganese composite oxides represented by the formula (where M = Fe, Co, Ni, Cu, or Zn); LiMn 2 O 4 ;Disulfide compounds;Fe 2 (MoO 4 ) 3 The positive electrode active material may include one or a mixture of two or more of the above. Preferably, the positive electrode active material may include one or more transition metals.

[0072] The negative electrode includes a negative electrode current collector and a negative electrode active material layer on at least one surface of the current collector, the negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin. The negative electrode includes a lithium metal oxide, a carbon such as a non-graphitizable carbon or a graphite-based carbon; LixFe 2 O 3 (0≦x≦1), LixWO 2 (0≦x≦1), Si, SiO x(0 < x < 2), silicon-based materials such as SiC and 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; SnO, SnO 2 , PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2 O 4 , Sb 2 O 5 , GeO, GeO 2 , Bi 2 O 3 , Bi 2 O 4 , and Bi 2 O 5 and metal oxides such as; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; may include one or a mixture of two or more selected from titanium oxides.

[0073] The conductive material may be 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 cylinder shape with a nanosize diameter of a graphite sheet and sp 2The carbon nanotube has a bond structure and exhibits conductive or semiconductive properties depending on the angle and structure of the graphite plane. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), and multi-walled carbon nanotubes (MWCNT) depending on the number of bonds forming the wall, and these carbon nanotubes can be appropriately selected depending on the use of the dispersion. More specifically, the carbon nanotube may be one or a mixture of two or more conductive materials 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.

[0074] As the binder resin, a binder resin that is usually used for electrodes of electrochemical elements can be used. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples of suitable cellulose acetate copolymers include, but are not limited to, cyanoethyl acetate propionate, cyanoethyl pullulan, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, and carboxyl methyl cellulose.

[0075] The electrolyte is A + B - A salt having the structure: + Li + , Na + , K+ or a combination thereof, - PF 6 - , B.F. 4 - , Cl - , Br - , I - , ClO 4 - , AsF 6 - , C.H. 3 CO 2 - , C.F. 3 SO 3 - , N(CF 3 SO 2 ) 2 - , C(CF 2 SO 2 ) 3 - or a combination thereof may be dissolved or dissociated in an organic solvent such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone, or a mixture thereof.

[0076] The electrochemical device including the electrode assembly may be a lithium secondary battery. The battery may be used as a unit cell, a battery module including the unit cell, or a battery pack including the battery module. The battery pack may be used as a power source for various electrical devices. Examples of the device include small devices such as computers, mobile phones, and power tools; electric vehicles that are 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 medium- to large-sized devices, including power storage systems, but are not limited to these.

[0077] Another embodiment of the present invention provides a method for manufacturing a separator for an electrochemical device, comprising forming a porous coating layer including a first polymer binder and inorganic particles on at least one surface of a porous polymer substrate. Any overlapping content with that described in the separator for an electrochemical device is replaced with the description of the previous embodiment.

[0078] The step of forming the porous coating layer may include preparing a coating slurry including a first polymer binder, inorganic particles, and a dispersion medium, applying the coating slurry to the porous polymer substrate, and drying the coating slurry. The first polymer binder and the inorganic particles may have different ligands introduced therein. The coating slurry may further include a second polymer binder to which no ligand is introduced.

[0079] The step of forming the porous coating layer may further include a step of corona-discharging at least one surface of the porous polymer substrate before applying the coating slurry to the porous polymer substrate. The step of corona-discharging at least one surface of the porous polymer substrate may prevent a decrease in adhesion between the surface of the porous polymer substrate and the surface of the coating layer at high temperatures, and may prevent a decrease in adhesion between the surface of the polymer substrate and the surface of the coating layer due to an electrolyte.

[0080] The corona discharge treatment may be performed by treating at least one surface of the porous polymer substrate in air at a voltage of about 0.1 kV to 10 kV. For example, the corona discharge treatment may be performed in air at a voltage of 0.2 kV to 9 kV, 0.3 kV to 8 kV, 0.4 kV to 7 kV, 0.5 kV to 6 kV, 0.6 kV to 5 kV, 0.7 kV to 4 kV, 0.8 kV to 3 kV, 0.9 kV to 2 kV, or 1.0 kV to 2 kV. Preferably, the corona discharge treatment may be performed in air at a voltage of 1.8 kV. By adjusting the applied voltage of the corona discharge treatment within the above range, an appropriate number of functional groups can be formed on the surface of the polymer substrate, and damage to the surface of the polymer substrate can be prevented.

[0081] The step of forming the porous coating layer may include applying the coating slurry to the porous polymer substrate to coat it. For example, the coating may be formed by a method such as, but not limited to, a bar coater, a wire bar coater, a roll coater, a spray coater, a spin coater, an inkjet coater, a screen coater, a reverse coater, a gravure coater, a knife coater, a slot die coater, a hot melt coater, a comma coater, or a direct metering coater. Preferably, the step of forming the porous coating layer may be simultaneously coating the coating slurry on both sides of the porous polymer substrate using a bar coater or a slot die coater.

[0082] The step of forming the porous coating layer may include applying the coating slurry to a porous polymer substrate, and then drying or heating the coating layer to evaporate the dispersion medium contained in the coating layer. The removal of the dispersion medium may be performed at a temperature at which only the dispersion medium contained in the coating layer can be evaporated without deforming the polymer binder contained in the coating layer. For example, the removal of the dispersion medium may be performed by heating the coating layer at a predetermined temperature, provided that the temperature of the surface of the coating layer does not exceed 60° C. When the coating layer is heated under the above conditions, the thermal energy is first used to heat the dispersion medium to cause a phase change, and may not be used to deform the polymer binder.

[0083] The present invention will be described in more detail below with reference to specific examples and experimental examples. The following examples and experimental examples are provided to illustrate the present invention, and the present invention is not limited to the following examples and experimental examples.

[0084] Example 1 Coating slurry preparation The first polymer binder was prepared by introducing nitrilotriacetic acid (NTA) as a ligand into the acrylate polymer binder. Specifically, 11 g of pentafluorophenyl acrylate (PFA) was dissolved in 200 mL of anhydrous dimethylformamide (DMF) at room temperature (25°C), and then amine-substituted nitrilotriacetic acid (NH 2 (CH 2 ) 4 The mixture was mixed with a solution of 12 g of NTA dissolved in 10 mL of distilled water. 210 mL of triethylamine (TEA) was further added to the mixed solution, and the mixture was heated at 50° C. for 6 hours. The mixed solution was dialyzed against distilled water to remove dimethylformamide, and dried in a vacuum oven at 40° C. for 1 hour to obtain 8.5 g of a first polymer binder having nitrilotriacetic acid (weight average molecular weight 58,000).

[0085] As the second polymer binder, commercially available polyvinylidene fluoride-hexafluoropropylene (weight average molecular weight: 100,000, HFP substitution degree: 10%) was used.

[0086] N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole and TEOS (tetraethyl orthosilicate) were added to ethanol, and condensed under the catalysts of hydrochloric acid and sodium chloride to form oligomers. The oligomerized silanes were mixed and then co-condensed under the catalyst of triethylamine to obtain imidazole-substituted silica particles in a gel state. The gel was washed with water and then ethanol in a centrifuge, and then dried in a vacuum oven at 40°C for 24 hours to obtain imidazole-incorporated silica (average particle size (D50): 500 nm) in a solid state.

[0087] At room temperature (25° C.), 15.2 g of the first polymer binder (NTA-introduced acrylic binder), 15.2 g of the second polymer binder (PVDF-HFP), 26.9 g of the inorganic particles (imidazole-introduced silica), and 0.76 g of PAA as an additive were added to 124 mL of NMP, and the mixture was stirred with a shaker for 60 minutes to prepare a coating slurry.

[0088] Preparation of porous polymer substrates The porous polymer substrate was (MI: 0.2g / 10min, T m The experimental conditions were: temperature: 135° C., porosity: 45%, average pore size: 45 nm, and a polyethylene film having a size of 20 cm×30 cm and a thickness of 9 μm was used.

[0089] Separation membrane manufacturing The coating slurry was coated on both sides of a polyethylene film using a bar coater to form a coating layer having a thickness of 3 μm (the composition of the porous coating layer was 20 wt % of the first polymer binder, 20 wt % of the second polymer binder, and 60 wt % of inorganic particles based on the total weight of the porous coating layer). The polyethylene film on which the coating layer was formed was subjected to a low-temperature airflow to remove the dispersion medium, and the process was repeated five times to prepare a separator with a total thickness of 15 μm.

[0090] Example 2 Coating slurry preparation As the first polymer binder, commercially available polyvinylimidazole (weight average molecular weight 100,000) was used.

[0091] As the second polymer binder, a commercially available polyvinylidene fluoride-hexafluoropropylene was used as in Example 1.

[0092] Inorganic particles were produced by introducing nitrilotriacetic acid as a ligand into silica. Specifically, 40.5g of amine-substituted cationic silica gel and 33.5g of nitrilotriacetic acid were added to 500mL of pyridine to prepare a dispersion. The dispersion was reacted by stirring at 90℃ for 3 hours under a reflux system, and then cooled to room temperature, and 0.5M of sodium bicarbonate was added to neutralize unreacted nitrilotriacetic acid. The reactant was washed in a centrifuge with distilled water, ethanol, and diethyl ether in that order, and then dried at room temperature for 24 hours to obtain silica (average particle size (D50): 700nm) with nitrilotriacetic acid introduced in a solid state.

[0093] At room temperature (25° C.), 15.2 g of the first polymer binder (polyvinylimidazole), 15.2 g of the second polymer binder (PVDF-HFP), 26.9 g of the inorganic particles (NTA-introduced silica), and 0.76 g of PAA as an additive were added to 124 mL of NMP, and the mixture was stirred with a shaker for 60 minutes to prepare a coating slurry.

[0094] Separation membrane manufacturing A separation membrane was prepared in the same manner as in Example 1 using the same porous polymer substrate as in Example 1.

[0095] Comparative Example 1 A separator was manufactured in the same manner as in Example 1, except that the NTA-doped acrylic binder was used as the first polymer binder, PVDF-HFP was used as the second polymer binder, and the NTA-doped silica was used as the inorganic particles when preparing the coating slurry (the composition of the porous coating layer was 20 wt % of the first polymer binder, 20 wt % of the second polymer binder, and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0096] Comparative Example 2 A separator was prepared in the same manner as in Example 1, except that polyvinylimidazole was used as the first polymer binder, PVDF-HFP was used as the second polymer binder, and the imidazole-doped silica was used as the inorganic particles when preparing the coating slurry (the composition of the porous coating layer was 20 wt % of the first polymer binder, 20 wt % of the second polymer binder, and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0097] Comparative Example 3 A separator was manufactured in the same manner as in Example 1, except that the NTA-doped acrylic binder was used as the first polymer binder, PVDF-HFP was used as the second polymer binder, and silica was used as the inorganic particles when preparing the coating slurry (the composition of the porous coating layer was 20 wt % of the first polymer binder, 20 wt % of the second polymer binder, and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0098] Comparative Example 4 A separator was prepared in the same manner as in Example 1, except that polyvinylimidazole was used as the first polymer binder, PVDF-HFP was used as the second polymer binder, and silica of Comparative Example 3 was used as the inorganic particles when preparing the coating slurry (the composition of the porous coating layer was 20 wt % of the first polymer binder, 20 wt % of the second polymer binder, and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0099] Comparative Example 5 A separator was prepared in the same manner as in Example 1, except that polyvinylimidazole and NTA-introduced acrylic binder were used as the first polymer binder, PVDF-HFP was used as the second polymer binder, and silica of Comparative Example 3 was used as the inorganic particles when preparing the coating slurry (the composition of the porous coating layer was 10 wt % polyvinylimidazole, 10 wt % NTA-introduced acrylic binder, 20 wt % second polymer binder, and 60 wt % inorganic particles, based on the total weight of the porous coating layer).

[0100] Comparative Example 6 A separator was prepared in the same manner as in Example 1, except that the first polymer binder was not used in preparing the coating slurry, and PVDF-HFP was used as the second polymer binder and NTA-doped silica was used as the inorganic particles (the composition of the porous coating layer was 40 wt % of the second polymer binder and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0101] Comparative Example 7 A separator was prepared in the same manner as in Example 1, except that the first polymer binder was not used in preparing the coating slurry, and PVDF-HFP was used as the second polymer binder and imidazole-doped silica was used as the inorganic particles (the composition of the porous coating layer was 40 wt % of the second polymer binder and 60 wt % of the inorganic particles, based on the total weight of the porous coating layer).

[0102] Comparative Example 8 A separator was prepared in the same manner as in Example 1, except that the first polymer binder was not used in preparing the coating slurry, and PVDF-HFP was used as the second polymer binder, and NTA-doped silica and imidazole-doped silica were used as the inorganic particles (the composition of the porous coating layer was 40 wt % of the second polymer binder, 30 wt % of the NTA-doped silica, and 30 wt % of the imidazole-doped silica, based on the total weight of the porous coating layer).

[0103] Experimental example: Confirmation of the physical properties of separation membranes The physical properties of the separation membranes produced in the examples and comparative examples were confirmed and are shown in Table 1 below.

[0104] Measurement of air permeability The air permeability was measured using a Gurley densometer (Gurley 4110N) by measuring the air permeability of a sample by measuring the diameter of the sample with 100 cc of air and the area of ​​the sample with 28.6 mm diameter and 645 mm area. 2 The time it took for the solution to permeate the separation membrane was measured.

[0105] Measurement of battery life characteristics The lithium manganese composite oxide, conductive material (Denka black), and binder (PVdF) were weighed out to a weight ratio of 95:2.5:2.5, and then mixed in N-methylpyrrolidone (NMP) to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated on an aluminum foil having a thickness of 20 μm to a thickness of 200 μm, and then rolled and dried to prepare a positive electrode.

[0106] A 200 μm thick Li metal plate was used as the negative electrode, and the positive and negative electrodes were laminated with the separator of the Example or Comparative Example sandwiched therebetween, and then inserted into an aluminum pouch.

[0107] The aluminum pouch was filled with a solvent in which ethylene carbonate (EC) / ethyl methyl carbonate (EMC) was mixed in a weight ratio of 3 / 7, and 3 mol of vinylene carbonate (VC), 1.5 mol of propane sultone (PS), 1 mol of ethylene sulfate (ESa), and lithium salt LiPF were added as additives. 6 1 g of electrolyte containing 1 mol was injected and the pouch was sealed to prepare a cell.

[0108] The fabricated cell was charged and discharged once at a rate of 0.1 C in a voltage range of 3.0 V to 4.4 V in a 25° C. chamber, and the charge and discharge were repeated 300 times at a rate of 1 C to confirm the life characteristics. The life characteristics were expressed as a capacity retention rate calculated by calculating the ratio of the discharge capacity after 300 cycles to the initial discharge capacity.

[0109] In addition, the resistance was measured before and after the 300 cycles to confirm the rate of increase in resistance.

[0110] [Table 1] As can be seen from Table 1 above, in the case of the examples, the capacity retention rate after 300 cycles is relatively higher than that of the comparative examples, and the resistance increase rate after 300 cycles of the examples is relatively lower than that of the comparative examples.

[0111] Although the present invention has been described above with reference to the preferred embodiments, it will be understood that those skilled in the art or those having ordinary knowledge in the art can modify and change the present invention in various ways without departing from the spirit and technical scope of the present invention as described in the claims below. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

Claims

1. A porous polymeric substrate; and a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer including a first polymer binder and inorganic particles; Including, The separator for an electrochemical device, wherein different ligands are introduced into the first polymer binder and the inorganic particles, respectively.

2. The separator for an electrochemical device according to claim 1 , wherein the first polymer binder and the inorganic particles form a coordinate bond with a single metal ion.

3. 2. The separator for an electrochemical device according to claim 1, wherein the first polymer binder and the inorganic particles are each independently chemically bonded to one or more ligands selected from a first ligand having one coordination denticity and a second ligand having two or more coordination denticities.

4. The first ligand is 4. The separator for an electrochemical device according to claim 3, which is at least one selected from the group consisting of imidazole, pyrazole, triazole, tetrazole, indazole, benzimidazole, azaindole, purine, and derivatives thereof.

5. The second ligand is 4. The separator for an electrochemical device according to claim 3, which is at least one selected from the group consisting of nitrilotriacetic acid, iminodiacetic acid, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, and derivatives thereof.

6. The separator for an electrochemical device according to claim 5 , wherein the inorganic particles have surfaces to which the second ligand is chemically bonded.

7. The inorganic particles are 2. The separator for an electrochemical device according to claim 1, wherein the porous coating layer is present in an amount of 40 to 80 wt % based on the total weight of the porous coating layer.

8. The porous coating layer further comprises a second polymeric binder; The separator for an electrochemical device according to claim 1 , wherein the content of the first polymer binder is greater than or equal to the content of the second polymer binder.

9. An electrochemical device comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, An electrochemical element, wherein the separator is the separator for electrochemical elements according to claim 2 .

10. The electrochemical device according to claim 9 , wherein the metal ions are generated during a charge / discharge process of the electrochemical device.

11. The electrochemical element according to claim 10 , wherein the metal ions are transition metal ions derived from the positive electrode.

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