Separator for electrochemical device and electrochemical device comprising same

Abstract

A separator for an electrochemical device comprises a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate, the porous coating layer comprising inorganic particles and a polymer binder, wherein the inorganic particles have a polymer coating layer containing an amine group on the surface and at least a portion of the polymer binder is crosslinked with the polymer containing the amine group.

Description

Separator for electrochemical devices and electrochemical devices containing the same

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

[0002] Electrochemical devices convert chemical energy into electrical energy using electrochemical reactions. Recently, lithium secondary batteries have been widely used due to their high energy density and voltage, long cycle life, and wide range of applications.

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

[0004] Meanwhile, to improve the performance and safety of secondary batteries employing electrochemical devices, improvements are being made to the characteristics of each of the positive electrode, negative electrode, electrolyte, and separator.

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

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

[0007] One aspect of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate, wherein the porous coating layer comprises inorganic particles and a polymer binder, wherein the inorganic particles have a polymer coating layer including an amine group formed on the surface of the inorganic particles, and at least a portion of the polymer binder is crosslinked with the polymer including the amine group.

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

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

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

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

[0012] According to one embodiment of the present invention, about 60 wt% to 80 wt% of the polymer binder is crosslinked with the polymer including the amine group.

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

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

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

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

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

[0018] According to another embodiment of the present invention, an electrochemical device is provided, which includes an anode, a cathode, and a separator disposed between the anode and the cathode, wherein the separator is a separator for an electrochemical device according to the above aspect.

[0019] The above electrochemical device may be a lithium secondary battery.

[0020] A separator for an electrochemical device according to one embodiment of the present invention provides improved dimensional stability in a wet state when immersed in an electrolyte. For example, the separator exhibits a thermal shrinkage in the TD direction of less than about 10% under high-temperature conditions of about 130°C or higher, thereby preventing electrode exposure due to thermal shrinkage of the separator.

[0021] Figure 1 is an image showing the appearance of a separator according to Example 1 and b Comparative Example 1, which was inserted into a pouch together with an electrolyte and stored in a 135°C convection oven for 30 minutes according to an experimental example, and then the separator was taken out.

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

[0023] 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 practice it; however, this is only an example, and the scope of the rights of the present invention is not limited by the following contents.

[0024] The term "comprises" as used herein is used to list materials, compositions, devices, and methods useful in the present invention, but is not limited to the listed examples.

[0025] In this specification, singular forms also include plural forms unless specifically stated otherwise in the text.

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

[0027] In this specification, when it is said that a component is “provided on”, this does not exclude other components being placed in between, unless otherwise specifically stated, but rather means that other components may be placed thereon.

[0028] In this specification, “%” means weight percent unless explicitly indicated otherwise.

[0029] As used herein, the terms "about" and "substantially" are used to mean a range or approximation of a numerical value or degree, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting the disclosure, which includes precise or absolute numerical values ​​provided to aid understanding of the present invention.

[0030] As used herein, “electrochemical device” refers to a primary battery, a secondary battery, a super capacitor, etc.

[0031] As used herein, “wet state” means a state in which the separator is impregnated with at least a portion of the electrolyte.

[0032] The separator may include a porous coating layer comprising a polymer binder and inorganic particles on at least one surface of a porous substrate. The inorganic particles are connected to other inorganic particles by the polymer binder to form an interstitial volume, and lithium ions can move through the interstitial volume. In addition to fixing the inorganic particles, the polymer binder may also provide adhesiveness to the porous coating layer, and the porous coating layer may adhere to the porous substrate and the electrode, respectively.

[0033] A porous coating layer including a polymer binder and inorganic particles can prevent thermal shrinkage of a porous polymer substrate, and a separator including the porous coating layer exhibits excellent dimensional stability in a dry state without an electrolyte. However, in a wet state where the separator is impregnated with an electrolyte, the polymer binder swells due to the electrolyte, or the separator is exposed to a temperature of about 130°C or higher during the operation of a lithium secondary battery including the separator, thereby reducing the adhesive strength of the polymer binder. In such a high-temperature wet state, the adhesive strength of the porous coating layer decreases, causing the separator to shrink significantly. In particular, a cylindrical battery in which an electrode assembly is wound and inserted into a case while tension is applied to the electrode assembly requires relatively less adhesive strength between the electrode and the separator than a pouch-type battery, and therefore has a problem in that the dimensional stability in a wet state is further reduced due to a small content of polymer binder.

[0034] In order to prevent such problems, the present invention provides a separator that secures dimensional stability under high temperature and wet conditions while maintaining a relatively low content of polymer binder in the porous coating layer.

[0035]

[0036] One embodiment of the present invention provides a separator for an electrochemical device, comprising a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate, wherein the porous coating layer comprises inorganic particles and a polymer binder, wherein the inorganic particles have a polymer coating layer formed on a surface thereof containing an amine group, and at least a portion of the polymer binder is crosslinked with the polymer containing the amine group.

[0037] According to one embodiment of the present invention, the porous polymer substrate is a porous membrane having a plurality of pores formed therein, which electrically insulates the positive and negative electrodes to prevent short circuits. For example, when the electrochemical device is a lithium secondary battery, the porous polymer substrate is 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 can form a three-dimensional network that connects the surface and the interior of the porous polymer substrate, and a fluid can pass through the porous polymer substrate through the pores.

[0038] According to one embodiment of the present invention, the porous polymer substrate uses a material that is physically and chemically stable with respect to an organic solvent, such as an electrolyte. For example, the porous polymer substrate includes, but is not limited to, a resin such as a polyolefin-based resin such as polyethylene, polypropylene, and polybutylene, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof. For example, a polyolefin-based resin can be used. A polyolefin-based resin can be processed into a relatively thin thickness and is easy to apply a coating slurry, making it suitable for the manufacture of an electrochemical device with a higher energy density.

[0039] According to one embodiment of the present invention, the porous polymer substrate has a single-layer or multi-layer structure. The porous polymer substrate includes two or more polymer resin layers having different melting points (Tm), thereby providing a shutdown function in the event of a high-temperature runaway of the battery. For example, the porous polymer substrate includes a polypropylene layer having a relatively high melting point and a polyethylene layer having a relatively low melting point. Alternatively, the porous polymer substrate may have a three-layer structure in which polypropylene, polyethylene, and polypropylene are laminated in that order. The polyethylene layer melts when the temperature of the battery rises above a predetermined temperature, thereby shutting down the pores, thereby preventing thermal runaway of the battery.

[0040] According to one embodiment of the present invention, the thickness of the porous polymer substrate is about 1 μm or more and 100 μm or less. For example, the thickness of the porous polymer substrate may be about 10 μm or more and 90 μm or less, about 20 μm or more and 80 μm or less, about 30 μm or more and 70 μm or less, or about 40 μm or more and 60 μm or less. Alternatively, the thickness of the polymer substrate may be about 1 μm or more and 30 μm or less. For example, the thickness of the polymer substrate may be about 5 μm or more and 15 μm or less, or about 8 μm or more and 13 μm or less. By controlling the thickness of the porous polymer substrate within the above-described range, the volume of the electrochemical device can be minimized while electrically insulating the positive and negative electrodes, thereby increasing the amount of active material included in the electrochemical device.

[0041] According to one embodiment of the present invention, the porous polymer substrate includes pores having an average diameter of about 0.01 μm to 1 μm. For example, the size of the pores included in the porous polymer substrate may be about 0.01 μm to 0.09 μm, about 0.02 μm to 0.08 μm, about 0.03 μm to 0.07 μm, or about 0.04 μm to 0.06 μm. Alternatively, the size of the pores may be about 0.02 μm to 0.06 μm. By controlling the pore size of the porous polymer substrate within the above-described range, the air permeability and ionic conductivity of the entire manufactured membrane can be controlled.

[0042] According to one embodiment of the present invention, the porous polymer substrate has a permeability of about 10 s / 100cc or more and 100 s / 100cc or less. For example, the permeability of the porous polymer substrate may be about 10 s / 100cc or more and 90 s / 100cc or less, about 20 s / 100cc or more and 80 s / 100cc or less, about 30 s / 100cc or more and 70 s / 100cc or less, or about 40 s / 100cc or more and 60 s / 100cc or less. Alternatively, the permeability of the porous polymer substrate may be about 50 s / 100cc or more and 70 s / 100cc or less. When the permeability of the porous polymer substrate is within the above-described range, the permeability of the manufactured separator can be provided within a range suitable for securing the output and cycle characteristics of the electrochemical device.

[0043] According to one embodiment of the present invention, the air permeability (s / 100cc) means the time (in seconds) it takes for 100cc of air to pass through a porous polymer substrate or membrane of a predetermined area under a constant pressure. The air permeability can be measured using a Gurley densometer according to ASTM D 726-58, ASTM D726-94 or JIS-P8117. For example, using a 4110N device from Gurley, the air at a pressure of 0.304kPa or a pressure of 1.215 kN / m 2 100 cc of air under the pressure of water occupies 1 square inch (or 6.54 cm 2 ) can be used to measure the time it takes for 100 cc of air to pass through a 1-square-inch sample under a constant pressure of 4.8 inches of water at room temperature. For example, using the Asahi Seico EG01-55-1MR equipment, the time it takes for 100 cc of air to pass through a 1-square-inch sample can be measured.

[0044] According to one embodiment of the present invention, the porous polymer substrate has a porosity of about 10 vol% or more and 60 vol% or less. For example, the porosity of the porous polymer substrate may be about 15 vol% or more and 55 vol% or less, about 20 vol% or more and 50 vol% or less, about 25 vol% or more and 45 vol% or less, or about 30 vol% or more and 40 vol% or less. Alternatively, the porosity of the porous polymer substrate may be about 30 vol% or more and 50 vol% or less. When the porosity of the porous polymer substrate is in the above-described range, the ionic conductivity of the manufactured separator can be provided in a range suitable for securing the output and cycle characteristics of the electrochemical device.

[0045] According to one embodiment of the present invention, the porosity refers to the volume ratio of pores to the total volume of the porous polymer substrate. The porosity can be measured by a method known in the art. For example, it can be measured by the BET (Brunauer Emmett Teller) measurement method using nitrogen gas adsorption, the capillary flow porosimetry method, or the water or mercury intrusion method.

[0046] According to one embodiment of the present invention, the porous coating layer is formed on at least one surface of the porous polymer substrate and includes inorganic particles and a polymer binder.

[0047] According to one embodiment of the present invention, the porous coating layer is formed by coating at least one surface of a porous polymer substrate with a coating slurry containing inorganic particles, a polymer binder, and a dispersion medium. For example, the separator can be manufactured by applying the coating slurry to at least one surface of a porous polymer substrate and then drying to remove the dispersion medium. The porous coating layer includes an interstitial volume in which the inorganic particles are connected by the polymer binder, allowing lithium ions to pass through, and is adhered to the porous polymer substrate to prevent thermal shrinkage of the porous polymer substrate.

[0048] According to one embodiment of the present invention, the coating slurry includes a dispersion medium to dissolve or disperse at least a portion of the polymer binder and disperse inorganic particles. The coating slurry is used in which the polymer binder and inorganic particles are uniformly dispersed by controlling the type and content of the dispersion medium. For example, the dispersion medium is one selected from the group consisting of water, ethanol, acetone, isopropyl alcohol (IPA), dimethylacetamide (DMAc), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), acetonitrile, and combinations thereof. Using the above-described type of dispersion medium, a porous coating layer in which inorganic particles are uniformly dispersed can be formed.

[0049] According to one embodiment of the present invention, the coating slurry has a viscosity of about 100 cps or more and 1,000 cps or less. For example, the viscosity of the coating slurry may be about 200 cps or more and 900 cps or less, about 300 cps or more and 800 cps or less, about 400 cps or more and 700 cps or less, or about 500 cps or more and 600 cps or less. Alternatively, the viscosity of the coating slurry may be about 300 cps or more and 800 cps or less. By controlling the viscosity of the coating slurry within the above-described range, a porous coating layer can be formed through continuous application to a porous polymer substrate.

[0050] According to one embodiment of the present invention, the coating slurry further includes additives such as a dispersant, a surfactant, an antifoaming agent, and a flame retardant to improve dispersibility and flame retardancy and to 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. By using the above-described type of dispersant, the stability of the coating slurry can be improved and the uniformity of the porous coating layer formed with the coating slurry can be secured.

[0051] According to one embodiment of the present invention, the additive is included in an amount of about 0 wt% or more and 5 wt% or less based on the total weight of the coating slurry. For example, the content of the additive may be included in an amount of about 0.01 wt% or more and 4 wt% or less, about 0.1 wt% or more and 3 wt% or less, or about 1 wt% or more and 2 wt% or less. Alternatively, the content of the additive may be about 3 wt% or more and 5 wt% or less. By controlling the content of the additive within the above-described range, uniform dispersion and stability of the inorganic particles included in the coating slurry can be achieved.

[0052] According to one embodiment of the present invention, the dispersion medium included in the coating slurry is removed by drying or heating after the formation of the porous coating layer. For example, the porous coating layer includes the dispersion medium at about 5 ppm or less. Alternatively, the porous coating layer may be composed of an acrylic polymer binder, a copolymer binder, and inorganic particles. In the process of removing the dispersion medium, a plurality of pores are formed on the surface and inside of the porous coating layer. The pores include interstitial volumes formed between the inorganic particles and have a structure that forms a three-dimensional network through which a fluid can pass.

[0053] According to one embodiment of the present invention, the thickness of the porous coating layer is about 0.1 ㎛ or more and 10 ㎛ or less. For example, the thickness of the porous coating layer may be about 0.5 ㎛ or more and 9.5 ㎛ or less, about 1.0 ㎛ or more and 9.0 ㎛ or less, about 1.5 ㎛ or more and 8.5 ㎛ or less, about 2.0 ㎛ or more and 8.0 ㎛ or less, about 2.5 ㎛ or more and 7.5 ㎛ or less, about 3.0 ㎛ or more and 7.0 ㎛ or less, about 3.5 ㎛ or more and 6.5 ㎛ or less, about 4.0 ㎛ or more and 6.0 ㎛ or less, or about 4.5 ㎛ or more and 5.5 ㎛ or less. Alternatively, the thickness of the porous coating layer may be about 0.5 ㎛ or more and 5 ㎛ or less. Alternatively, the thickness of the porous coating layer may be about 0.5 ㎛ or more and 2 ㎛ or less. By controlling the thickness of the porous coating layer within the above-described range, shrinkage of the porous polymer substrate can be minimized and stable adhesion to the porous polymer substrate can be achieved.

[0054] According to one embodiment of the present invention, the porous coating layer includes inorganic particles having a polymer coating layer including an amine group formed on a surface thereof, and a polymer binder, wherein at least a portion of the polymer binder is crosslinked with the polymer including the amine group. For example, the polymer binder may include two or more different types of polymer binders, at least one of which may be crosslinked with the polymer including the amine group. The polymer binder crosslinking with the polymer including the amine group forms a physical or chemical bond with the polymer including the amine group. Alternatively, the polymer binder crosslinking with the polymer including the amine group may be thermally crosslinked via the amine group. The polymer binder is bound to one or more inorganic particles through crosslinking with the coating layer of the inorganic particles to form an interstitial volume. The polymer binder forms and maintains a more solid bond with the inorganic particles having the coating layer formed thereon compared to the inorganic particles without the coating layer, and the porous coating layer including the polymer binder can exhibit reduced thermal shrinkage in a high-temperature wet state.

[0055] According to one embodiment of the present invention, the inorganic particles are electrochemically stable. The inorganic particles are used in the operating voltage range of the electrochemical device (e.g., Li / Li). + There is no particular limitation as long as no oxidation and / or reduction reaction occurs at 0 to 5 V as a standard. For example, when using inorganic particles with a high dielectric constant as inorganic particles, it contributes to an increase in the degree of dissociation of electrolyte salt, such as lithium salt, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte. For the reasons described above, it is preferable that the inorganic particles 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 Zr1-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.

[0056] In addition, inorganic particles having lithium ion transfer capability, i.e., inorganic particles containing lithium element but having the function of transferring lithium ions without storing lithium, can be used. Non-limiting examples of inorganic particles having lithium ion transfer capability 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), 14Li2O-9Al2O3-38TiO2-39P2O5, etc. (LiAlTiP) x O y Series glass (0 <x < 4, 0 < y < 13), 리튬란탄티타네이트(Li x La y TiO3, 0 < x <2, 0 <y <3), Li 3.25 Ge 0.25 P 0.75 Lithium germanium thiophosphate (Li) such as S4 x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li 3 N ), etc. x N y, 0 < x <4, 0 < y < 2), SiS2 series glass (Li) such as Li3PO4-Li2S-SiS2 x Si y S z , 0 < x < 3, 0 <y < 2, 0 < z < 4), LiI-Li2S-P2S5등과 같은 P2S5계열 glass(Li x P y S z , 0 < x < 3, 0< y < 3, 0 < z < 7) or mixtures thereof.

[0057] In addition, as the inorganic particles, inorganic particles having flame retardancy can be used to impart flame retardant properties to the separator or to prevent a rapid increase in temperature inside the electrochemical device. 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.

[0058] According to one embodiment of the present invention, the average particle diameter (D50) of the inorganic particles is about 50 nm or more and 5,000 nm or less. For example, the average particle diameter (D50) of the inorganic particles may be about 100 nm or more and 4,500 nm or less, about 200 nm or more and 4,000 nm or less, about 300 nm or more and 3,000 nm or less, about 400 nm or more and 2,000 nm or less, or about 500 nm or more and 1,000 nm or less. Alternatively, the average particle diameter of the inorganic particles may be about 200 nm or more and 500 nm or less. If the average particle diameter of the inorganic particles is less than about 50 nm, as the specific surface area increases, an additional 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 approximately 5000 nm, the uniformity of the coating layer surface may be reduced and damage to the porous polymer substrate or electrode may occur during lamination.

[0059] According to one embodiment of the present invention, the aspect ratio of the inorganic particles is about 1 or more and 2 or less. For example, the aspect ratio of the inorganic particles may be about 1.1 or more and 1.9 or less, about 1.2 or more and 1.8 or less, about 1.3 or more and 1.7 or less, or about 1.4 or more and 1.6 or less. By controlling the aspect ratio of the inorganic particles within the above-described range, it is possible to form a porous coating layer including an interstitial volume that facilitates the movement of the polymer binder through the pores between the inorganic particles and ultimately enables the movement of lithium ions.

[0060] According to one embodiment of the present invention, the BET specific surface area of ​​the inorganic particles is about 5 m 2 / g or more 25 m 2 / g or less. For example, the BET surface area of ​​the above inorganic particles is about 6 m 2 / g or more 24 m 2 / g or less, about 7 m 2 / g or more 23 m 2 / g or less, about 8 m 2 / g or more 22 m 2 / g or less, about 9 m 2 / g or more 21 m 2 / g or less, about 10 m 2 / g or more than 20 m 2 / g or less, about 11 m 2 / g or more than 19 m 2 / g or less, about 12 m 2 / g or more than 18 m 2 / g or less, about 13 m 2 / g or more than 17 m 2 / g or less or about 14 m 2 / g or more 26 m 2 / g or less. By controlling the BET specific surface area of ​​the inorganic particles within the above-described range, the movement of the polymer binder through the pores between the inorganic particles can be controlled.

[0061] According to one embodiment of the present invention, the density of the inorganic particles is about 3 g / cm 3 More than 9 g / cm 3 Below. For example, the density of the above inorganic particles is about 3.5 g / cm 3 More than 8.5 g / cm 3 Below, about 4 g / cm 3 More than 8 g / cm 3 Below, about 4.5 g / cm 3 More than 7.5 g / cm 3 Below, about 5 g / cm 3 More than 7 g / cm 3 Less than or about 5.5 g / cm 3 More than 6.5 g / cm 3 It may be less than or equal to about 3 g / cm. Alternatively, the density of the inorganic particles may be about 3 g / cm. 3 More than 4.5 g / cm 3By controlling the density of the inorganic particles within the above-described range, uniform dispersion of the inorganic particles within the porous coating layer can be achieved, and thermal shrinkage of the porous polymer substrate can be reduced.

[0062] According to one embodiment of the present invention, the inorganic particle has a coating layer formed on its surface, which includes a polymer containing an amine group. For example, the inorganic particle and the coating layer may form a core-shell structure. Alternatively, the inorganic particle may be spherical, and the coating layer may completely surround the inorganic particle with a constant thickness.

[0063] According to one embodiment of the present invention, the polymer including an amine group includes both a catechol group and an amine group. For example, the polymer including an amine group may be at least one selected from dopamine and derivatives thereof. The polymer including an amine group may form a coating layer by physically or chemically bonding with the inorganic particles through the catechol groups, and may expose one or more amine groups on the surface of the coating layer. For example, the inorganic particles may include one or more hydroxyl groups on the surface, or may be surface-treated to have hydroxyl groups, and the polymer including an amine group forms a coating layer through hydrogen bonding with the hydroxyl groups through the catechol groups, and exposes the amine groups on the surface of the coating layer. The method of bonding the polymer including an amine group and the inorganic particles is not limited thereto.

[0064] According to one embodiment of the present invention, the thickness of the coating layer formed on the surface of the inorganic particles is about 2 nm to 20 nm. For example, the thickness of the coating layer formed on the surface of the inorganic particles may be about 2 nm to 18 nm, about 4 nm to 16 nm, about 6 nm to 14 nm, or about 8 nm to 12 nm. Alternatively, the thickness of the coating layer may be about 2 nm to 5 nm. By controlling the thickness of the coating layer within the above-described range, the coating layer is prevented from being detached from the inorganic particles under the operating conditions of the electrochemical device, and crosslinking with the polymer binder is formed, thereby reducing thermal shrinkage of the separator.

[0065] According to one embodiment of the present invention, the polymer binder is crosslinked with the polymer including an amine group, and includes at least one selected from the group consisting of dextrin, polyetheretherketone (PEEK), polyethersulfone (PES), and polyacrylamide (PAAm). The polymer binder is crosslinked with the polymer including an amine group through a carboxyl group. Alternatively, the polymer including an amine group is dopamine, and the polymer binder forms a hydrogen bond with a hydroxyl group of the dopamine through the amine group. The polymer binder has a high glass transition temperature (Tg) or decomposition temperature (Td), and thus provides dimensional stability to the separation membrane at high temperatures, and at the same time, forms a bond with the coating layer to prevent deformation of the porous coating layer.

[0066] According to one embodiment of the present invention, the polymer binder comprises a (co)polymer of a monomer selected from the group consisting of acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and carboxyethyl acrylate, which is crosslinked with the polymer containing the amine group. The (co)polymer may contain a carboxyl group and may be crosslinked by forming an amide bond with an amine group exposed on the surface of the coating layer. The polymer binder forms a stable bond with one or more inorganic particles, thereby forming an interstitial volume and preventing deformation of the porous coating layer.

[0067] According to one embodiment of the present invention, the polymer binder further comprises a fluorinated polymer binder in addition to being crosslinkable with the polymer containing the amine group. For example, the fluorinated polymer binder may be a homopolymer of vinylidene fluoride, a copolymer of vinylidene fluoride and another copolymerizable monomer, or a mixture thereof.

[0068] According to one embodiment of the present invention, the polymer binder comprises about 60 wt% to 80 wt% of a polymer capable of crosslinking with the polymer including an amine group, based on the total weight of the polymer binder. For example, about 66 wt% to 75 wt% of the polymer binder may be crosslinked with the polymer including an amine group, i.e., the coating layer formed on the surface of the inorganic particle. By controlling the content of the polymer binder crosslinked with the inorganic particle on which the coating layer is formed within the above-described range, it is possible to form a porous coating layer that allows lithium ions to pass through but does not deform in a high-temperature wet state.

[0069] According to one embodiment of the present invention, the porous coating layer contains the inorganic particles in an amount of about 90 wt% to 95 wt% based on the total weight of the porous coating layer. For example, the porous coating layer may contain the inorganic particles in an amount of about 90 wt% to 95 wt%, about 91 wt% to 92 wt%, or about 93 wt% to 94 wt%. Alternatively, the porous coating layer may contain the inorganic particles in an amount of about 92 wt% to 94 wt%. By controlling the content of the inorganic particles within the above-described range, a separator having mechanical strength and thermal properties suitable for a cylindrical battery can be manufactured.

[0070] According to one embodiment of the present invention, the loading amount of the porous coating layer per unit area of ​​the porous polymer substrate in the separation membrane is about 5.5 g / m 2 More than 8.0 g / m 2 Below. For example, the loading of the porous coating layer is about 5.7 g / m 2 More than 7.8 g / m 2 Below, about 5.9 g / m 2 More than 7.6 g / m 2 Below, about 6.1 g / m 2 Above 7.4 g / m 2 Below, about 6.3 g / m 2 More than 7.2 g / m 2 Below, about 6.5 g / m 2 More than 7.0 g / m 2 or less, or about 6.7 g / m 2 More than 6.8 g / m 2 It may be less than or equal to about 5.6 g / m. Alternatively, the loading of the porous coating layer may be about 5.6 g / m. 2 More than 6.5 g / m 2 By controlling the loading amount of the porous coating layer within the above-described range, the durability of the separator against the electrolyte can be secured, thereby reducing thermal shrinkage in a high-temperature wet state.

[0071] According to one embodiment of the present invention, the separator further includes a second polymer coating layer formed on the surface of the porous coating layer. For example, the second polymer coating layer may include a polymer containing an amine group. Alternatively, the polymer containing an amine group of the second polymer coating layer may include both a catechol group and an amine group. For example, the polymer containing an amine group may be at least one selected from dopamine and derivatives thereof.

[0072] According to one embodiment of the present invention, the second polymer coating layer is formed by applying a solution of a polymer containing an amine group to the surface of a separator including a porous polymer substrate and a porous coating layer and drying the solution. For example, a separator having a second polymer coating layer including the polymer formed thereon can be obtained by immersing the separator in a polymer solution containing an amine group.

[0073] For example, the polymer including the amine group may be dopamine, and a separator including a porous polymer substrate and a porous coating layer may be immersed in a dopamine solution to obtain a separator having a second polymer coating layer including polydopamine formed thereon. The immersion time may be about 40 to 48 hours, and the loading amount of polydopamine included in the second polymer coating layer may be about 0.0005 g / m. 2 More than 0.01 g / m 2 It may be as follows. By controlling the amount of polydopamine included in the second polymer coating layer within the above-described range, the wet state thermal shrinkage of the separator can be reduced even under high temperature conditions.

[0074] According to one embodiment of the present invention, at least a portion of the polymer including an amine group of the second polymer coating layer is crosslinked with the polymer binder of the porous coating layer. For example, the polymer binder included in the porous coating layer can be thermally crosslinked via the amine group. The crosslinking can be performed by applying a polymer solution including the amine group to the surface of the porous coating layer and then drying it, or by performing a separate heat treatment after drying it. The porous coating layer and the second polymer coating layer can form and maintain a more solid bond through crosslinking between the polymers, and the separator in which the bond is formed can exhibit a further reduced thermal shrinkage in a high-temperature wet state.

[0075] According to one embodiment of the present invention, the second polymer coating layer further includes dextrin. The dextrin provides durability to the second polymer coating layer, thereby improving dimensional stability of a separator including the second polymer coating layer. The dextrin uniformly disperses the polymer including the amine group, and can maintain dimensional stability even when an external force is applied while an electrode attached to or adjacent to the separator shrinks or expands. Alternatively, the dextrin may be cyclodextrin, and for example, may be at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0076] According to one embodiment of the present invention, the second polymer coating layer includes the polymer including the amine group and the dextrin in a weight ratio of about 1:500 to 1:1000. For example, the second polymer coating layer may include polydopamine and dextrin in a weight ratio of about 1:600 ​​to 1:900, or about 1:700 to 1:800. By controlling the content of the polydopamine and the dextrin within the above-described range, uniform dispersion of the polydopamine included in the porous coating layer and reduction of the wet state thermal shrinkage rate at high temperatures of the separator can be achieved simultaneously.

[0077] According to one embodiment of the present invention, the separator for the electrochemical device has a permeability of about 50 s / 100cc or more and about 150 s / 100cc or less. For example, the permeability of the separator may be about 60 s / 100cc or more and 140 s / 100cc or less, about 70 s / 100cc or more and 130 s / 100cc or less, about 80 s / 100cc or more and 120 s / 100cc or less, or about 90 s / 100cc or more and 110 s / 100cc or less. Alternatively, the permeability of the separator may be about 100 s / 100cc or more and 120 s / 100cc or less. When the permeability of the separator is within the above-described range, the output, stability, and cycle characteristics of the electrochemical device can be secured.

[0078] According to one embodiment of the present invention, the thermal shrinkage of the separator for the electrochemical device is less than about 10%. For example, the wet state thermal shrinkage of the separator is less than about 10%. For example, the wet state thermal shrinkage is a dimensional change rate based on when the separator is exposed to about 135°C for about 30 minutes in a state of being impregnated with an electrolyte.

[0079] According to one embodiment of the present invention, when a cell is manufactured using the separator for an electrochemical device, the cell has an electrical resistance of about 0.5 Ohm or more and 1.5 Ohm or less. For example, the electrical resistance of the cell may be about 0.6 Ohm or more and 1.4 Ohm or less, about 0.7 Ohm or more and 1.3 Ohm or less, about 0.8 Ohm or more and 1.2 Ohm or less, or about 0.9 Ohm or more and 1.1 Ohm or less. Alternatively, the electrical resistance of the cell may be about 0.6 Ohm or more and 0.8 Ohm or less.

[0080]

[0081] Another embodiment of the present invention provides an electrochemical device comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the separator is a separator for an electrochemical device as described above. The electrochemical device can be manufactured by inserting and sealing an electrode assembly comprising the positive electrode, the negative electrode, and the separator interposed between the positive electrode and the negative electrode into a case or pouch. An electrolyte may be injected into the case or pouch before sealing to impregnate the electrode assembly with the electrolyte. The shape of the case or pouch is not limited. For example, the electrochemical device can be a cylindrical, square, coin-shaped, or pouch-shaped lithium secondary battery.

[0082] According to one embodiment of the present invention, the positive electrode and the negative electrode are coated by applying and drying an electrode active material on at least one surface of each current collector. The current collector may be a material that is conductive and does not cause a chemical change in the electrochemical device. For example, the current collector for the positive electrode may be, but is not limited to, aluminum, nickel, titanium, sintered carbon, stainless steel; aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.; and the like. For example, the current collector for the negative electrode may be, but is not limited to, copper, nickel, titanium, sintered carbon, stainless steel; copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.; and the like. The current collector may be in various forms, such as a metal plate, film, foil, net, porous body, or foam body.

[0083] According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material is a layered compound such as lithium manganese oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-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 by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn 1-x M xA lithium manganese composite oxide represented by O2 (wherein, M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein, M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; a disulfide compound; or a mixture of two or more of Fe2(MoO4)3.

[0084] According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The negative electrode includes carbon such as lithium metal oxide, non-graphitizable carbon, and graphitic carbon as the negative electrode active material; LixFe2O3(0≤x≤1), Li x WO2(0≤x≤1), Si, SiO x (0 <x<2), SiC, Si 합금 등의 실리콘계 재료; Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0085] According to one embodiment of the present invention, the conductive material is one or a mixture of two or more conductive materials selected from the group consisting of graphite, carbon black, carbon fibers or metal fibers, metal powders, conductive whiskers, conductive metal oxides, carbon nanotubes, activated carbon, and polyphenylene derivatives. The carbon nanotubes have a graphite sheet having a cylindrical shape with a nano-sized diameter, and sp 2 It has a bonding structure, and exhibits the characteristics of a conductor or a semiconductor depending on the angle and structure at which the graphite plane is rolled. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) depending on the number of bonds forming the wall, and these carbon nanotubes can be appropriately selected depending on the use of the dispersion. For example, the conductive material may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more conductive materials among these.

[0086] According to one embodiment of the present invention, the binder resin may be a binder resin commonly used in electrodes of electrochemical devices. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetate Examples thereof include, but are not limited to, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0087] According to one embodiment of the present invention, the electrolyte is A + B - As a salt with the same structure as A+ is Li + , Na + , K + Contains ions composed of alkali metal cations or combinations thereof, such as B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - A salt containing an anion such as or a combination thereof, which is dissolved or dissociated in an organic solvent consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma butyrolactone (γ-butyrolactone), or a mixture thereof.

[0088] For example, the electrolyte may include a solvent having a weight ratio of 3 / 7 of Ethylene Carbonate (EC) / Ethylmethyl Carbonate (EMC) or a solvent having a weight ratio of 20 / 5 / 75 of Ethylene Carbonate (EC) / Ethylmethyl Carbonate (EMC) / Dimethyl Carbonate (DMC), and the dimensional stability of the separator according to the above example may be maximized.

[0089] According to one embodiment of the present invention, the electrochemical device including the electrode assembly is a lithium secondary battery. Furthermore, the separator for an electrochemical device including the electrode assembly according to the present invention can be similarly applied to a sodium secondary battery manufactured using sodium ions as a positive electrode active material.

[0090] Additionally, unlike the lithium secondary battery described above, the lithium secondary battery according to another embodiment of the present invention may be an all-solid-state battery.

[0091] The battery can be used as a unit cell, and can be used as a battery module including the unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. The devices include, but are not limited to, small devices such as computers, mobile phones, and power tools, and medium to large devices such as electric vehicles including electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEV) that are powered by an electric motor and move; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems.

[0092]

[0093] Hereinafter, the present invention will be described in more detail through examples and experimental examples. The following examples and comparative experimental examples are intended to illustrate the present invention. The examples according to the present invention may be modified in various other forms, and the present invention is not limited to the following examples and experimental examples.

[0094] Example 1

[0095] Preparation of inorganic particles with a coating layer formed

[0096] In 1000 mL of basic aqueous solution (Tris-buffer, pH 8.5), 30 g of Al2O3 (particle size: 400 nm) as inorganic particles and 2 g of dopamine as a polymer containing an amine group were mixed, stored at 20°C for 4 hours, and then repeatedly ultrasonically washed with distilled water and completely dried at 50°C to obtain inorganic particles having a polydopamine coating layer (thickness: 2 nm) formed thereon.

[0097] Preparation of coating slurry

[0098] At room temperature (25°C), 1.5 g of polyacrylate as a polymer binder, 30 g of inorganic particles on which the polydopamine coating layer was formed, and 0.2 g of Si-based surfactant as an additive were added to 50 mL of water, and stirred for 60 minutes using a shaker to prepare a coating slurry in which the polymer binder and inorganic particles were dispersed.

[0099] Preparation of porous polymer substrates

[0100] As a porous polymer substrate (MI: 0.2 g / 10 min, T m : 135℃, porosity: 45%, average pore size: 45 nm) and a polyethylene film with a thickness of 9 ㎛ was used.

[0101] Manufacturing of membranes

[0102] The coating slurry was coated on both sides of a polyethylene film using a bar coater, so that each coating had a thickness of 2 ㎛ and a loading of 6.3 g / m 2 A coating layer was formed.

[0103] The process of applying a low-temperature airflow of 50°C to a polyethylene film on which a coating layer was formed to remove the dispersion medium was repeated five times, and the film was dried at 100°C for 10 minutes to perform cross-linking of polydopamine and polyacrylic acid, thereby manufacturing a separation membrane with a total thickness of 13 μm.

[0104] Example 2

[0105] Polymaleic acid is used as a polymer binder, and the loading of the porous coating layer is 6.0 g / m 2 A membrane was manufactured in the same manner as in Example 1, except that this was done.

[0106] Example 3

[0107] Dextrin is used as a polymer binder, and the loading of the porous coating layer is 6.4 g / m 2 Except for this, a separation membrane was manufactured in the same manner as in Example 1.

[0108] Example 4

[0109] PAAm was used as a polymer binder, and the loading of the porous coating layer was 5.7 g / m 2 Except for this, a separation membrane was manufactured in the same manner as in Example 1.

[0110] Example 5

[0111] A membrane was manufactured in the same manner as in Example 1, except that dextrin and PVdF-HFP were used as polymer binders in a weight ratio of 3:1.

[0112] Example 6

[0113] At room temperature (25°C), dopamine (2 mg / mL) and dextrin (50 mg / mL) were added to a 20 mM alkaline buffer solution (Tris-HCl buffer) in a petri dish, and the amounts added were adjusted so that the final dopamine and dextrin content was 1:1000. Thereafter, the lid of the petri dish was partially opened to prepare a dopamine and dextrin solution with a dissolved oxygen content of 9 ppm and a pH of 8.

[0114] The separator prepared in Example 1 was immersed in the above solution for 48 hours, and then dried at 60°C for 12 hours to manufacture a separator having a second polymer coating layer having a thickness of 0.5 μm.

[0115] Comparative Example 1

[0116] In the electrochemical device separator of Example 1, a separator was manufactured in the same manner as in Example 1, except that the amount of the inorganic particles was adjusted to 30 g and the amount of dopamine was adjusted to 0.5 g (coating layer thickness: 1 nm) when manufacturing the coating slurry.

[0117] Comparative Example 2

[0118] A separator was manufactured in the same manner as in Example 1, except that polyurethane was used as the polymer binder in the separator for the electrochemical device of Example 1.

[0119] Comparative Example 3

[0120] A separator was manufactured in the same manner as in Example 1, except that inorganic particles that did not form the coating layer were used in the separator for the electrochemical device of Example 1.

[0121] Comparative Example 4

[0122] A separator was manufactured in the same manner as in Example 2, except that inorganic particles that did not form the coating layer were used in the separator for the electrochemical device of Example 2.

[0123] Comparative Example 5

[0124] A separator was manufactured in the same manner as in Comparative Example 2, except that inorganic particles that did not form the coating layer were used in the separator for the electrochemical device of Example 2.

[0125] Comparative Example 6

[0126] A separator was manufactured in the same manner as in Example 5, except that dextrin and PVdF-HFP were used as the polymer binder in a weight ratio of 1:1 in the separator for the electrochemical device of Example 5.

[0127]

[0128] Experimental example. Confirmation of the physical properties of the membrane.

[0129] The properties of the membranes manufactured according to the examples and comparative examples are shown in Tables 1 and 2, respectively.

[0130] Confirmed improvement in wet state heat shrinkage

[0131] The membranes of the examples and comparative examples were prepared as 5 cm × 5 cm specimens and each was inserted into an aluminum pouch measuring 7 cm × 10 cm. 1 g of electrolyte was injected into the pouch, and the pouch was sealed.

[0132] The electrolyte used was a solvent containing ethylene carbonate (EC) / ethyl methyl carbonate (EMC) mixed in a weight ratio of 3 / 7, and 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.

[0133] After storing the above-mentioned sealed pouch in a 135°C convection oven for 30 minutes, the pouch was disassembled to obtain a separator, and the thermal shrinkage in the TD direction was calculated according to [(length of initial specimen - length after storage for @135 / 0.5 h) / (length of initial specimen)] × 100 (%).

[0134] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Whether a coating layer is formed on the surface of an inorganic particle ○○○○○○ Thickness of polydopamine coating layer (nm) 2 2 2 2 2 2 Type of polymer binder (weight ratio when mixed) Polyacrylate Polymaleic acid dextrin PAAm Dextrin, PVdF-HFP (3:1) Polyacrylate Thickness of separation membrane (㎛) 13.0 13.0 13.0 13.0 13.0 13.0 13.5 Porous coating layer loading amount (g / m) 2 )6.36.06.45.75.66.3Wet state thermal shrinkage @135℃ / 0.5h (TD(%))322691

[0135]

[0136] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Whether a coating layer is formed on the surface of an inorganic particle ○○×××× Thickness of the polydopamine coating layer (nm) 12---2 Type of polymer binder (weight ratio when mixed) Polyacrylate Polyurethane Polyacrylate Polymaleic acid Polyurethane Dextrin, PVdF-HFP (1:1) Thickness of the separation membrane (㎛) 13.0 13.0 13.0 13.0 13.0 13.0 Porous coating layer loading amount (g / m) 2 )6.26.36.36.16.15.2Wet state thermal shrinkage @135℃ / 0.5h (TD(%))102730282936

Claims

1. Comprising a porous polymer substrate and a porous coating layer formed on at least one surface of the porous polymer substrate, The above porous coating layer includes inorganic particles and a polymer binder, The above inorganic particles have a polymer coating layer containing an amine group formed on the surface of the above inorganic particles, A separator for an electrochemical device, wherein at least a portion of the polymer binder is crosslinked with a polymer containing an amine group.

2. In paragraph 1, A separator for an electrochemical device, wherein the polymer containing the above amine group is dopamine or a derivative thereof.

3. In paragraph 1, A separator for an electrochemical device, wherein the thickness of the coating layer is 2 nm to 20 nm.

4. In paragraph 1, The above polymer binder is, A separator for an electrochemical device, comprising at least one selected from the group consisting of dextrin, polyetheretherketone, polyethersulfone, and polyacrylamide.

5. In paragraph 1, The above polymer binder is, A separator for an electrochemical device, comprising a (co)polymer of a monomer selected from the group consisting of acrylate, acrylic acid, maleic acid, itaconic acid, methacrylic acid, and carboxyethyl acrylate.

6. In paragraph 1, A separator for an electrochemical device, wherein 60 to 80 wt% of the polymer binder is crosslinked with a polymer containing an amine group.

7. In paragraph 1, The loading amount of the porous coating layer per unit area of ​​the porous polymer substrate is 5.5 g / m 2 8 g / m 2 A separator for electrochemical devices.

8. In paragraph 1, The above porous coating layer is, A separator for an electrochemical device, comprising 90 to 95 wt% of the inorganic particles relative to the total weight of the porous coating layer.

9. In paragraph 1, It further includes a second polymer coating layer formed on the surface of the porous coating layer, The second polymer coating layer is, A separator for an electrochemical device, comprising a polymer containing the above amine group.

10. In paragraph 9, A separator for an electrochemical device, wherein at least a portion of the polymer containing the amine group of the second polymer coating layer is crosslinked with the polymer binder of the porous coating layer.

11. In paragraph 9, A separator for an electrochemical device, wherein the second polymer coating layer further comprises dextrin.

12. An electrochemical device comprising a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, The above separator is an electrochemical device, which is a separator for an electrochemical device according to claim 1.

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