Separation membrane for electrochemical elements and electrochemical elements 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 based on Korean Patent Application No. 10-2023-0044174, filed with the Korean Intellectual Property Office on April 4, 2023, the content of which is incorporated herein by reference in its entirety.

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

Background Art

[0003] An electrochemical device converts chemical energy into electrical energy using an electrochemical reaction. In recent years, lithium secondary batteries with high energy density, high voltage, long cycle life, and applicable in various fields have been widely used.

[0004] A lithium secondary battery may include an electrode assembly manufactured with a separator disposed between a positive electrode, a negative electrode, and the positive electrode and the negative electrode, and may be manufactured by housing the electrode assembly together with an electrolyte in a case. The positive electrode can provide lithium ions, and the lithium ions can pass through a separator made of a porous material and move to the negative electrode. The negative electrode can use a carbon-based active material having an electrochemical reaction potential close to that of lithium metal and capable of insertion and desorption of lithium ions.

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0006] One aspect of the present invention provides a separation membrane for an electrochemical device, which includes a porous polymer substrate, a first polymer binder, and inorganic particles, and includes a porous coating layer formed on at least one surface of the porous polymer substrate. Different ligands are introduced into the first polymer binder and the inorganic particles respectively, and the first polymer binder and the inorganic particles form a coordination bond with a single metal ion.

[0007] One or more ligands selected independently from a first ligand having a denticity of one and a second ligand having a denticity of two or more may be chemically bonded to the first polymer binder and the inorganic particles respectively.

[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 their surface.

[0011] The inorganic particles may be contained at 40 - 80% by weight based on the total weight of the porous coating layer.

[0012] The porous coating layer may further include a second polymer binder, and the content of the first polymer binder may be greater than or the same as the content of the second polymer binder.

[0013] Another aspect of the present invention provides an electrochemical element comprising a positive electrode, a negative electrode, and a separation membrane disposed between the positive electrode and the negative electrode, wherein the separation membrane is a separation membrane for an electrochemical element having the features described above.

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

[0015] The metal ions may be generated during the charging and discharging process of the electrochemical element.

[0016] The metal ion may be a transition metal ion originating from the positive electrode.

[0017] Another aspect of the present invention relates to an electrical device including an electrochemical element having the features described above.

[0018] Another aspect of the present invention relates to a method for manufacturing a separation membrane for an electrochemical element, comprising the step of forming a porous coating layer containing 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 containing the first polymer binder, the inorganic particles, and the dispersion medium, and applying the coating slurry to at least one surface of the porous polymer substrate.

[0020] The coating slurry may further contain a second polymer binder.

[0021] The step of forming the porous coating layer may further include treating at least one surface of the porous polymer substrate with corona discharge before applying the coating slurry to at least one surface of the porous polymer 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. [Effects of the Invention]

[0023] The separation membrane for electrochemical elements according to the present invention can adsorb metal ions generated during the charging and discharging process, thereby preventing performance degradation due to the deposition of impurities within the electrochemical element. [Modes for carrying out the invention]

[0024] The following describes in more detail each component of the present invention so that a person with ordinary skill in the art to which the present invention belongs can easily implement it. However, this is merely an example, and the scope of the rights of the present invention is not limited to the following.

[0025] As used herein, the term “including” is used to enumerate materials, compositions, apparatus, and methods useful for the present invention, and is not limited to such enumerated examples.

[0026] As used herein, “about,” “approximately,” and “substantially” are used to mean a range or near-range of numerical values ​​or degrees, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting disclosures that refer to precise or absolute numerical values ​​provided to aid in understanding the invention.

[0027] As used herein, "electrochemical elements" may refer to primary batteries, secondary batteries, supercapacitors, and the like.

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

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

[0030] Therefore, there is a need for a separation membrane for use in electrochemical elements containing a positive electrode active material that includes a transition metal such as manganese. This membrane can capture transition metal ions eluted from the positive electrode and prevent their migration to the negative electrode, thereby preventing degradation of the negative electrode and the electrochemical element containing it.

[0031] One specific example of the present invention provides a separation membrane for an electrochemical element, comprising a porous polymer substrate, a first polymer binder, and inorganic particles, wherein a porous coating layer is formed on at least one surface of the porous polymer substrate, and different ligands are introduced into the first polymer binder and the inorganic particles, respectively. The first polymer binder and the inorganic particles form coordination bonds with a single metal ion.

[0032] The porous polymer substrate is a porous membrane with multiple pores formed therein, which may electrically insulate the positive and negative electrodes to prevent short circuits. For example, if the electrochemical element is a lithium secondary battery, the porous polymer substrate may be an ion-conducting barrier that blocks electrical contact between the positive and negative electrodes while allowing lithium ions to pass through. At least some of the pores can form a three-dimensional network connecting the surface and interior of the porous polymer substrate, allowing fluids to pass through the porous polymer substrate via the pores.

[0033] The porous polymer substrate can be made of a material that is physically and chemically stable with respect to an electrolyte, which is an organic solvent. For example, the porous polymer substrate may include, but is not limited to, resins such as polyethylene, polypropylene, polybutylene and other polyolefins, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimidoamide, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof. Preferably, polyolefin resins can be used. Polyolefin resins can be processed to relatively thin thicknesses and are easy to apply coating slurries to, making them suitable for the manufacture of electrochemical elements 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 with different melting points (Tm) and may provide a shutdown function in the event of a high-temperature runaway of the battery. For example, the porous polymer substrate may include a polypropylene layer with a relatively high melting point and a polyethylene layer with 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 that order. The polyethylene layer can melt and shut down the pores as the battery temperature rises above a predetermined temperature, thereby preventing thermal runaway of the battery.

[0035] The thickness of the porous polymer substrate may be approximately 1 μm to 100 μm. For example, the thickness of the porous polymer substrate may be approximately 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 approximately 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, it is possible to minimize the volume of the electrochemical element while electrically insulating the positive and negative electrodes, thereby increasing the amount of active material contained in the electrochemical element.

[0036] The porous polymer substrate may contain pores with an average diameter of approximately 0.01 μm to 1 μm, such as round, circular, or elliptical shapes. For example, the size of the pores contained in the porous polymer substrate may be approximately 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. In one specific example, the size of the pores may be approximately 0.02 μm to 0.06 μm. By adjusting the size of the pores in the porous polymer substrate within the above range, the permeability and ionic conductivity of the entire separation membrane produced can be adjusted.

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

[0038] The aforementioned air permeability (s / 100cc) refers to the time (in seconds) it takes for 100cc of air to pass through a porous polymer substrate or separation membrane of a predetermined area under constant pressure. This air permeability can be measured using a Gurley densometer in accordance with ASTM D 726-58, ASTM D726-94, or JIS-P8117. For example, using a Gurley 4110N instrument, it can measure air at a pressure of 0.304 kPa or 1.215 kN / m³. 2 Under water pressure, 100cc of air covers 1 square inch (or 6.54cm). 2 The time it takes for a sample to pass through can be measured. For example, using the EG01-55-1MR instrument from Asahi Seiko, the time it takes for 100cc of air to pass through a 1 square inch sample can be measured at room temperature and under constant pressure in 4.8 inches of water.

[0039] The porous polymer substrate may have a porosity of approximately 10 vol% to 60 vol%. For example, the porosity of the porous polymer substrate may be approximately 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 approximately 30 vol% to 50 vol%. When the porosity of the porous polymer substrate is within the above range, the ionic conductivity of the manufactured separation membrane can be provided within a range suitable for ensuring the output and cycle characteristics of the electrochemical element.

[0040] The porosity refers to the ratio of the volume of pores to the total volume of the porous polymer substrate. The porosity can be measured by methods known in the art. For example, it can be measured by the Brunauer-Emmett-Teller (BET) method utilizing nitrogen gas adsorption, the capillary flow porometer, or the water or mercury osmosis method.

[0041] The porous coating layer is formed on at least one surface of the porous polymer substrate and may contain a first polymer binder and inorganic particles. Different ligands may be introduced to the first polymer binder and the inorganic particles, respectively. The expression "introduced" ligands to the first polymer binder and the inorganic particles means that the ligands are chemically bonded to the polymer binder and / or inorganic particles. The method of chemical bonding of the ligands is not limited to the extent that the coordination ability of the ligands to metal ions is maintained, and methods known in the art may be used. The first polymer binder may have ligands chemically bonded via predetermined portions of repeating units. The inorganic particles may be chemically bonded to ligands via functional groups exposed on the particle surface, or the surface of the inorganic particles may be modified with predetermined functional groups before chemical bonding with the ligands is formed via the functional groups.

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

[0043] The first polymer binder and the inorganic particles may each be chemically bonded to 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 can simultaneously form a coordination bond with a single metal ion. The first ligand and the second ligand may each be chemically bonded to one or more of the first polymer binder and the inorganic particles independently. Preferably, the first polymer binder may be chemically bonded to the first ligand and the inorganic particles may be chemically bonded to the second ligand, or vice versa.

[0044] 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. The first ligand contains an aromatic heterocycle and can form a coordination bond with a metal ion at one site. The derivative is not limited in type, as it can form a coordination bond with a metal ion and can also 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 one or more 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, containing two or more carboxyl groups, and capable of forming coordinate bonds with metal ions at two or more locations. The derivative is not limited in type, as long as it can form coordinate bonds with metal ions and also form chemical bonds with the first polymer binder or inorganic particles. Preferably, the second ligand can be selected from nitrilotriacetic acid, iminodiacetic acid, or derivatives thereof.

[0046] Preferably, the first polymer binder may be chemically bound to the first ligand, and the inorganic particles may be chemically bound to the second ligand. The second ligand may have lower stability within the electrochemical element compared to the first ligand. The second ligand may cause side reactions with the electrolyte within the electrochemical element. Therefore, binding the second ligand to the surface of the inorganic particles may be advantageous for maintaining the adsorption capacity of metal ions, rather than binding the second ligand to the first polymer binder, which may be dissolved or swelled by the electrolyte.

[0047] In one 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 those contained in the electrochemical element and may be those generated during the charging and discharging 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 eluted from the positive electrode active material. The divalent ions can be coordinated with one nitrilotriacetic acid molecule and two imidazole molecules, with six occlusions per ion. The metal ions can be coordinated with the first polymer binder and inorganic particles to form a complex, which can suppress migration to the negative electrode and side reactions with the electrolyte.

[0048] The porous coating layer may further contain a second polymer binder. The second polymer binder does not contain a ligand. The first polymer binder and the second polymer binder can bind the inorganic particles contained in the porous coating layer and impart adhesive strength to the porous coating layer. The first polymer binder contains the aforementioned ligand and is used for the adsorption of metal ions, and its adhesive strength may be lower than that of the second polymer binder. The second polymer binder can provide safety for the separation membrane by ensuring that the porous coating layer maintains 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 binders within the above range, a porous coating layer capable of metal ion adsorption performance and stable adhesion to the porous substrate can be formed.

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

[0050] The aforementioned acrylic polymer binder is (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 It may contain one or more monomers 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 as repeating units.

[0051] For example, the acrylic polymer binder may contain 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 binder. For example, the fluorine-based polymer binder may be one or more 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, it may be a copolymer containing polyvinylidene fluoride.

[0053] One or more 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 adjusting the particle size of the polymer binder particles within the above range, it is possible to simultaneously ensure the lithium ion migration path and the adhesion 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 approximately 40,000 to 500,000. For example, the weight-average molecular weight of the polymer binder may be approximately 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 approximately 40,000 to 100,000, and the weight-average molecular weight of the second polymer binder may be approximately 40,000 to 200,000. By adjusting the weight-average molecular weight of the polymer binder within the above range, it is possible to form a porous coating layer in which the polymer binder is uniformly dispersed and which simultaneously exhibits adsorption capacity for metal ions and adhesion capacity to porous polymer substrates.

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

[0056] The porous coating layer may contain inorganic particles in an amount of approximately 40% to 80% by weight relative to the total weight of the porous coating layer. For example, the inorganic particle content relative to the total weight of the porous coating layer may be approximately 45% to 75% by weight, 50% to 70% by weight, or 55% to 65% by weight. For example, the inorganic particle content may be approximately 60% to 80% by weight. A porous coating layer containing inorganic particles within the above range can reduce the thermal shrinkage of the porous polymer substrate and prevent short circuits of electrodes due to shrinkage of the separation membrane.

[0057] The inorganic particles can be electrochemically stable. The inorganic particles are within the operating voltage range of the electrochemical element (for example, Li / Li +There is no particular limitation as long as oxidation and / or reduction reactions do not occur at a reference of 0 to 5 V. In particular, when using inorganic particles with a high dielectric constant as the inorganic particles, it is possible to contribute to an increase in the dissociation degree of electrolyte salts in the liquid electrolyte, for example, lithium salts, and improve the ionic conductivity of the electrolyte solution. For the reasons described above, the inorganic particles may include high-dielectric-constant inorganic particles having 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)O3 (PZT), b 1-x La x Zr 1-y Ti y O3 (PLZT, 0 < x < 1, 0 < y < 1), Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, Al(OH)3, SiC, AlOOH, TiO2, or mixtures thereof, and the like.

[0058] In addition, as the inorganic particles, inorganic particles having lithium ion transfer ability, that is, inorganic particles containing lithium element but not storing lithium and having a function of moving lithium ions 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 x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y -based glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li 3.25 Ge 0.25P 0.75 Lithium germanium thiophosphate such as S4 (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride such as Li3N (Li x N y , 0 < x < 4, 0 < y < 2), SiS2-based glass such as Li3PO4-Li2S-SiS2 (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4), P2S5-based glass such as LiI-Li2S-P2S5 (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 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, etc.

[0060] The average particle size (D50) of the inorganic particles may be approximately 10 nm to 10,000 nm. For example, the average particle size (D50) of the inorganic particles may be approximately 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 approximately 100 nm to 700 nm. If the average particle size of the inorganic particles is less than 10 nm, as the specific surface area increases, more polymer binder is 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 electrode during lamination.

[0061] The porous coating layer may be formed by coating one surface of the porous polymer substrate with a coating slurry containing the first polymer binder, the inorganic particles, and the dispersion medium. The coating slurry may further contain a second polymer binder. For example, the separation membrane can be manufactured by applying the coating slurry to at least one surface of the porous polymer substrate, and then drying it to remove the dispersion medium. The porous coating layer may have a porous structure in which the inorganic particles include the first polymer binder or interstitial volumes linked by the first polymer binder and the second polymer binder. The porous coating layer can adhere to the porous polymer substrate while allowing lithium ions to pass through, thereby preventing thermal shrinkage of the porous polymer substrate.

[0062] The coating slurry contains a dispersion medium that can dissolve or disperse at least a portion of the polymer binder and disperse the inorganic particles. The coating slurry can 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 can be formed.

[0063] The coating slurry can have a viscosity of approximately 100 cps to 1,000 cps. For example, the viscosity of the coating slurry may be approximately 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 approximately 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 separation films by continuous coating onto porous polymer substrates, and thus making it impossible to ensure productivity.

[0064] The coating slurry may further contain additives such as dispersants, surfactants, defoamers, flame retardants, and wetting agents to improve dispersibility and flame retardancy and enhance the uniformity of the porous coating layer formed. For example, the dispersant may contain one or more 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. By using the above-described types of dispersants, the stability of the coating slurry can be improved and the uniformity of the porous coating layer formed from the coating slurry can be ensured.

[0065] The additive may be present in an amount of 0% to 5% by weight relative to the total weight of the coating slurry. Specifically, the content of the additive may be 0.01% to 4% by weight, 0.1% to 3% by weight, or 1% to 2% by weight. Preferably, the content of the additive may be approximately 3% to 5% by weight. By adjusting the content of the additive within the above range, uniform dispersion and stability of the inorganic particles contained 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 the dispersion medium at a concentration of about 5 ppm or less. Preferably, the porous coating layer may consist of a first polymer binder and inorganic particles, or a first polymer binder, a second polymer binder and inorganic particles. During the process of removing the dispersion medium, a plurality of pores may be formed on the surface and inside the porous coating layer. These pores may include interstitial volumes formed between the inorganic particles and may have a structure that forms a three-dimensional network through which fluid can pass.

[0067] The thickness of the porous coating layer may be approximately 1 μm to 15 μm. For example, the thickness of the porous coating layer may be approximately 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 approximately 1 μm to 5 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.

[0068] The separation membrane for the electrochemical element can have an air permeability of approximately 50 s / 100 cc to 150 s / 100 cc. For example, the air permeability of the separation membrane may be 60 s / 100 cc to 140 s / 100 cc, 70 s / 100 cc to 130 s / 100 cc, 80 s / 100 cc to 120 s / 100 cc, or 90 s / 100 cc to 110 s / 100 cc. For example, the air permeability of the separation membrane may be approximately 100 s / 100 cc to 120 s / 100 cc. When the air permeability of the separation membrane is within the above range, the output, stability, and cycle characteristics of the electrochemical element can be ensured.

[0069] Another specific example of the present invention provides an electrochemical element comprising a positive electrode, a negative electrode, and a separation membrane interposed between the positive electrode and the negative electrode, wherein the separation membrane is the separation membrane for the electrochemical element of the above-described example. The above-described electrochemical element can be manufactured by inserting an electrode assembly comprising a positive electrode, a negative electrode, and a separation membrane interposed between the positive electrode and the negative electrode into a case or pouch and sealing it. Before sealing the case or pouch, an electrolyte can be poured in to impregnate the electrode assembly with the electrolyte. The shape of the case or pouch is not limited. For example, the electrochemical element may be cylindrical, rectangular, coin-type, or pouch-type lithium secondary battery.

[0070] The positive electrode and the negative electrode may be coated with an electrode active material applied to and dried on at least one surface of their respective current collectors. The current collectors can be made of materials that are conductive without causing chemical changes to the electrochemical elements. For example, the positive electrode current collector may be made of aluminum, nickel, titanium, calcined carbon, stainless steel, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., but is not limited thereto. For example, the negative electrode current collector may be made of copper, nickel, titanium, calcined carbon, stainless steel, or copper or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., but is not limited thereto. The current collectors can be in various forms, such as thin metal sheets, films, foils, nets, porous materials, or foams.

[0071] The positive electrode comprises a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector, comprising a positive electrode active material, a conductive material, and a binder resin. The positive electrode active material is a layered compound such as lithium manganese composite oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented as O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 1-x M xLithium manganese composite oxides represented by O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01-0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a part of Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; one or a mixture of two or more of Fe2(MoO4)3 may be included. Preferably, the positive electrode active material may contain one or more transition metals.

[0072] 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. As the negative electrode active material, the negative electrode includes carbon such as lithium metal oxide, graphitized carbon, and graphite-based carbon; LixFe2O3 (0≤x≤1), LixWO2 (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; 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 a mixture of two or more selected from titanium oxides may be included.

[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 bonded structure and exhibits conductive or semiconductor properties depending on the angle and structure in which the graphite surface is wound. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) depending on the number of bonds forming the wall, and these carbon nanotubes can be appropriately selected depending on the application of the dispersion. More specifically, it 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 conductive materials from this group.

[0074] As the binder resin, a binder resin commonly used for electrodes of electrochemical elements can be used. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include, but are not limited to, acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methylcellulose.

[0075] The aforementioned electrolyte is A + B - A salt with a structure like this, + is Li + kaNa + , K+ It contains alkali metal cations such as, or ions consisting of combinations thereof, B - PF6 - BF4 - Cl - , Br - , I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as these, or ions consisting of combinations thereof, may be dissolved or dissociated in organic solvents 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, or mixtures thereof.

[0076] The electrochemical element including the electrode assembly may be a lithium secondary battery. The battery can be used as a unit cell, a battery module including the unit cell, or a battery pack including the battery module. The battery pack can be used as a power source for various electrical devices. The aforementioned devices include, but are not limited to, small devices such as computers, mobile phones, and power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs) that are powered by electric motors; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and medium to large devices such as power storage systems.

[0077] Another specific example of the present invention provides a method for manufacturing a separation membrane for an electrochemical element, which includes the step of forming a porous coating layer containing a first polymer binder and inorganic particles on at least one surface of a porous polymer substrate. Any content that overlaps with the description of the separation membrane for the electrochemical element described above will be replaced by the description of the above specific example.

[0078] The step of forming the porous coating layer may include preparing a coating slurry containing a first polymer binder, inorganic particles, and a dispersion medium, and applying the coating slurry to the porous polymer substrate and drying it. The first polymer binder and the inorganic particles may each have different ligands introduced into them. The coating slurry may further contain a second polymer binder that does not have a ligand introduced into it.

[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 can prevent a decrease in the bonding strength between the surface of the porous polymer substrate and the surface of the coating layer at high temperatures, and can prevent a decrease in the bonding strength between the surface of the polymer substrate and the surface of the coating layer due to electrolytes.

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

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

[0082] The step of forming the porous coating layer may involve 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 carried out at a temperature that allows only the dispersion medium contained in the coating layer to evaporate without deforming the polymer binder contained in the coating layer. For example, the removal of the dispersion medium may involve heating the coating layer to a predetermined temperature, provided that the temperature of the coating layer surface does not exceed 60°C. When heating the coating layer under the above conditions, the thermal energy is first used to heat the dispersion medium and cause a phase change, and does not necessarily have to 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 cases. The following examples and experimental cases are for illustrative purposes only and do not limit the present invention to the following examples and experimental cases.

[0084] Example 1 Preparation of coating slurry A first polymer binder was prepared by introducing nitrilotriacetic acid (NTA) as a ligand to an acrylate-based 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 mixed with a solution of 12 g of amine-substituted nitrilotriacetic acid (NH2(CH2)4NTA) 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 with distilled water to remove dimethylformamide, and dried in a vacuum oven at 40°C for 1 hour to obtain 8.5 g of the first polymer binder containing 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 oligomerized by condensation under the catalysis of hydrochloric acid and sodium chloride, respectively. After mixing the oligomerized silanes, co-condensation was performed under the catalysis of triethylamine to obtain imidazole-substituted silica particles in a gel state. The gel was washed with water and then ethanol using a centrifuge, and then dried in a vacuum oven at 40°C for 24 hours to obtain solid silica (average particle size (D50): 500 nm) into which imidazole had been introduced.

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

[0088] Preparation of porous polymer substrates As a porous polymer substrate, (MI: 0.2g / 10min, T m A polyethylene film measuring 20cm x 30cm with a thickness of 9μm was used, with a temperature of 135℃, porosity of 45%, and average pore size of 45nm.

[0089] Manufacturing of separation membranes A polyethylene film was coated on both sides with the coating slurry using a bar coater to form a coating layer with a thickness of 3 μm for each layer (the composition of the porous coating layer was 20% by weight of the first polymer binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer). A separation membrane with a total thickness of 15 μm was produced by repeating the process of removing the dispersion medium by applying a low-temperature airflow to a polyethylene film on which a coating layer had been formed, five times.

[0090] Example 2 Preparation of coating slurry As the primary polymer binder, commercially available polyvinylimidazole (weight-average molecular weight 100,000) was used.

[0091] As the second polymer binder, 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, 40.5 g of amine-substituted cationized silica gel and 33.5 g of nitrilotriacetic acid were added to 500 mL of pyridine to prepare a dispersion. The dispersion was stirred under reflux at 90°C for 3 hours to react, then cooled to room temperature, and 0.5 M sodium bicarbonate was added to neutralize the unreacted nitrilotriacetic acid. The reaction product was washed in distilled water, ethanol, and diethyl ether in that order using a centrifuge, and then dried at room temperature for 24 hours to obtain silica (average particle size (D50): 700 nm) with introduced nitrilotriacetic acid 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-modified silica), and 0.76 g of PAA as an additive were added to 124 mL of NMP, and the mixture was stirred in a shaker for 60 minutes to produce a coating slurry.

[0094] Manufacturing of separation membranes A separation membrane was manufactured using the same porous polymer substrate as used in Example 1 and the same method as in Example 1.

[0095] Comparative Example 1 The separation membrane was manufactured in the same manner as in Example 1, except that the NTA-introduced acrylic binder was used as the first polymer binder, PVDF-HFP as the second polymer binder, and NTA-introduced silica as the inorganic particles during the production of the coating slurry. (The composition of the porous coating layer was 20% by weight of the first polymer binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer.)

[0096] Comparative Example 2 The separation membrane was manufactured in the same manner as in Example 1, except that polyvinylimidazole was used as the first polymer binder, PVDF-HFP as the second polymer binder, and silica into which the imidazole was introduced as inorganic particles during the production of the coating slurry (the composition of the porous coating layer was 20% by weight of the first polymer binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0097] Comparative Example 3 The separation membrane was manufactured in the same manner as in Example 1, except that the acrylic binder with NTA introduced was used as the first polymer binder, PVDF-HFP as the second polymer binder, and silica as inorganic particles during the production of the coating slurry (the composition of the porous coating layer was 20% by weight of the first polymer binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0098] Comparative Example 4 The separation membrane was manufactured in the same manner as in Example 1, except that polyvinylimidazole was used as the first polymer binder, PVDF-HFP as the second polymer binder, and silica from Comparative Example 3 as inorganic particles during the production of the coating slurry (the composition of the porous coating layer was 20% by weight of the first polymer binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0099] Comparative Example 5 The separation membrane was manufactured 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 as the second polymer binder, and silica from Comparative Example 3 as inorganic particles during the production of the coating slurry (the composition of the porous coating layer was 10% by weight of polyvinylimidazole, 10% by weight of NTA-introduced acrylic binder, 20% by weight of the second polymer binder, and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0100] Comparative Example 6 The separation membrane was manufactured in the same manner as in Example 1, except that the first polymer binder was not used during the production of the coating slurry, and PVDF-HFP was used as the second polymer binder and NTA-introduced silica as inorganic particles (the composition of the porous coating layer was 40% by weight of the second polymer binder and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0101] Comparative Example 7 The separation membrane was manufactured in the same manner as in Example 1, except that the first polymer binder was not used during the production of the coating slurry, and PVDF-HFP was used as the second polymer binder and imidazole-introduced silica as the inorganic particles (the composition of the porous coating layer was 40% by weight of the second polymer binder and 60% by weight of inorganic particles, based on the total weight of the porous coating layer).

[0102] Comparative Example 8 The separation membrane was manufactured in the same manner as in Example 1, except that the first polymer binder was not used during the production of the coating slurry, and PVDF-HFP was used as the second polymer binder, and NTA-introduced silica and imidazole-introduced silica were used as inorganic particles (the composition of the porous coating layer was 40% by weight of the second polymer binder, 30% by weight of NTA-introduced silica, and 30% by weight of imidazole-introduced silica, based on the total weight of the porous coating layer).

[0103] Experimental example: Confirmation of 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 Air permeability was measured using an air permeability tester (Gurley densometer) (Gurley, 4110N), with 100cc of air measuring a diameter of 28.6mm and an area of ​​645mm². 2 The time it took for the substance to pass through the separation membrane was measured.

[0105] Measurement of battery life characteristics A lithium manganese-based composite oxide, conductive material (Denka black), and binder (PVdF) were weighed in a weight ratio of 95:2.5:2.5. These were then mixed in N-methylpyrrolidone (NMP) to produce a cathode active material slurry. This slurry was then coated onto a 20 μm thick aluminum foil to a thickness of 200 μm, followed by rolling and drying to produce the cathode.

[0106] A 200 μm thick Li metal plate was used as the negative electrode. The positive and negative electrodes were stacked with the separation film of the example or comparative example in between, and then inserted into an aluminum pouch.

[0107] A cell was manufactured by injecting 1 g of an electrolyte solution containing 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 into an aluminum pouch containing a solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) in a weight ratio of 3 / 7, and then sealing the pouch.

[0108] The manufactured cells were charged and discharged once in a 25°C chamber at a rate of 0.1C in the voltage range of 3.0V to 4.4V, and their life characteristics were confirmed by repeating the charging and discharging cycles 300 times at a rate of 1C each. The life characteristics were expressed as the capacity retention rate, calculated by determining the ratio of the discharge capacity after 300 cycles to the initial discharge capacity.

[0109] Furthermore, the resistance was measured before and after the aforementioned 300 cycles to confirm the rate of resistance increase.

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

[0111] While preferred embodiments of the present invention have been described above with reference to the present invention, a person skilled in the art or a person with ordinary knowledge of the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and technical domain of the invention as described in the claims below. Therefore, the technical scope of the present invention is not limited to what is described in the detailed description of the specification, but should be determined by the claims.

Claims

1. Porous polymer substrates; and A porous coating layer comprising a first polymer binder and inorganic particles, formed on at least one surface of the porous polymer substrate; Includes, A separation membrane for an electrochemical device, wherein the first polymer binder and the inorganic particles are each introduced with different ligands.

2. The separation membrane for an electrochemical element according to claim 1, wherein the first polymer binder and the inorganic particles form a coordination bond with a single metal ion.

3. The separation membrane for an electrochemical element according to claim 1, wherein the first polymer binder and the inorganic particles are each independently chemically bound to one or more ligands selected from a first ligand having one coordination site (dentity) and a second ligand having two or more coordination sites.

4. The first ligand is The separation membrane for an electrochemical element according to claim 3, which is one or more selected from the group consisting of imidazole, pyrazole, triazole, tetrazole, indazole, benzimidazole, azaindole, purine, and derivatives thereof.

5. The second ligand is The separation membrane for an electrochemical element according to claim 3, which is one or more selected from the group consisting of nitrilotriacetic acid, iminodiacetic acid, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, and derivatives thereof.

6. The separation membrane for an electrochemical element according to claim 5, wherein the inorganic particles have the second ligand chemically bonded to their surface.

7. The inorganic particles are, The separation membrane for an electrochemical element according to claim 1, comprising 40% to 80% by weight based on the total weight of the porous coating layer.

8. The porous coating layer further comprises a second polymer binder, The separation membrane for an electrochemical element 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 element comprising a positive electrode, a negative electrode, and a separation membrane disposed between the positive electrode and the negative electrode, The separation membrane is the separation membrane for the electrochemical element described in claim 2, wherein the electrochemical element is an electrochemical element.

10. The electrochemical element according to claim 9, wherein the metal ions are generated during the charging and discharging process of the electrochemical element.

11. The electrochemical element according to claim 10, wherein the metal ion is a transition metal ion derived from the positive electrode.

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