A self-supporting ceramic seperator for an electrochemical device and an electrochemical device comprising the same

Abstract

The present invention relates to a self-supporting ceramic separator for an electrochemical device and an electrochemical device including the same. Specifically, by appropriately controlling the content and arrangement of plate-shaped first inorganic particles and second inorganic particles which are zeolite-based inorganic particles, the heat resistance of the separator is improved, electrical short circuits between electrodes are prevented to enhance the safety of the battery, and high cell life characteristics are exhibited. The invention relates to a self-supporting ceramic separator for an electrochemical device and an electrochemical device including the same.

Description

Technology Field

[0001] The present invention relates to a self-supporting ceramic separator for an electrochemical device and an electrochemical device including the same. Specifically, it relates to a self-supporting ceramic separator for an electrochemical device that includes a first inorganic particle and a second inorganic particle, which exhibits improved heat resistance and high cell lifespan characteristics, and an electrochemical device including the same. Background Technology

[0002] Among the components of an electrochemical device, the separator comprises a porous polymer substrate located between the anode and cathode. It serves to isolate the anode and cathode, prevent electrical short circuits between the two electrodes, and allow the passage of electrolytes and ions. Although the separator itself does not participate in electrochemical reactions, its physical properties, such as wettability to the electrolyte, degree of porosity, and thermal shrinkage rate, affect the performance and safety of the electrochemical device.

[0003] Accordingly, various methods are being attempted to modify the physical properties of a coating layer by adding a coating layer to a porous polymer substrate to enhance the physical properties of the separation membrane, and by adding various materials to the coating layer. For example, inorganic materials may be added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic materials or hydrates may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0004] The separator can be bonded to the electrode through a lamination process, and to ensure adhesion between the electrode and the separator, a polymer binder can be added to the coating layer composition of the separator.

[0005] Meanwhile, polyolefin resins, which are widely used as porous polymer substrates for electrochemical devices, had a problem in that shrinkage occurred upon exposure to high temperatures, causing the anode and cathode to come into contact and resulting in an electrical short circuit between the two electrodes, and heat generation caused thermal runaway due to the decomposition reaction of the electrolyte and active material.

[0006] Therefore, research was needed on a self-supporting ceramic separator capable of improving heat resistance and durability by appropriately combining inorganic particles without a porous polymer substrate such as a polyolefin resin, and enhancing battery safety and lifespan characteristics by preventing electrical short circuits between electrodes. The problem to be solved

[0007] The technical problem to be solved by the present invention is to provide a self-supporting ceramic separator for an electrochemical device and an electrochemical device including the same, which can improve heat resistance and durability and enhance the stability and lifespan characteristics of a battery by comprising a first inorganic particle capable of preventing transition metals leached from the anode from moving to the cathode face by forming a plate-like, dense stacked structure, and a second inorganic particle capable of adsorbing gas and transition metals having a high specific surface area, while having a configuration without a porous polymer substrate.

[0008] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0009] One embodiment of the present invention provides a self-supporting ceramic separator for an electrochemical device comprising a first inorganic particle, a second inorganic particle, and a polymer binder, wherein the first inorganic particle is plate-shaped and the aspect ratio of the first inorganic particle is 10 or more and 300 or less.

[0010] According to one embodiment of the present invention, one surface of the first inorganic particle and one surface of the separation membrane may be arranged to face each other.

[0011] According to one embodiment of the present invention, the invention may comprise: a first layer in which the weight containing the first inorganic particle is greater than the weight containing the second inorganic particle; and a second layer provided on one surface of the first layer in which the weight containing the second inorganic particle is greater than the weight containing the first inorganic particle.

[0012] According to one embodiment of the present invention, the opposite side of one side of the first layer may be provided to face the cathode.

[0013] According to one embodiment of the present invention, the first inorganic particle may comprise one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof.

[0014] According to one embodiment of the present invention, the second inorganic particle is a zeolite-based inorganic material, and the second inorganic particle includes pores having a diameter of 0.5 nm or more and 0.9 nm or less, and the pores of the second inorganic particle may be substituted with metal ions.

[0015] According to one embodiment of the present invention, the average particle size (D50) of the second inorganic particle may be 1 μm or less.

[0016] According to one embodiment of the present invention, the thickness of the second layer may be 1 μm or more and 3 μm or less.

[0017] According to one embodiment of the present invention, the content of the first inorganic particle may be 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the coating layer.

[0018] According to one embodiment of the present invention, the polymer binder may be an acrylic binder, a polyvinylidene binder, or a combination thereof.

[0019] According to one embodiment of the present invention, the thickness of the separator may be 7 μm or more and 15 μm or less.

[0020] According to one embodiment of the present invention, the air permeability of the separator may be 170 sec / 100cc or less.

[0021] According to one embodiment of the present invention, the resistance of the separator may be 0.6 Ω or more and 1.2 Ω or less.

[0022] One embodiment of the present invention provides an electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode. Effects of the invention

[0023] In one embodiment of the present invention, a self-supporting ceramic separator for an electrochemical device can suppress thermal shrinkage at high temperatures.

[0024] A self-supporting ceramic separator for an electrochemical device according to one embodiment of the present invention can improve the stability and lifespan characteristics of a battery by preventing transition metals eluted from the anode from moving to the negative electrode surface. Brief explanation of the drawing

[0025] FIG. 1 is a schematic diagram of a self-supporting ceramic separator for an electrochemical device according to one embodiment of the present invention. FIG. 2 is a schematic diagram of an electrochemical element according to one embodiment of the present invention. Specific details for implementing the invention

[0026] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0027] In this specification, "A and / or B" means "A and B, or A or B".

[0028] In this specification, when a component is described as being "on" one component, this means that, unless specifically stated otherwise, other components may be placed in between, without excluding the placement of other components.

[0029] In this specification, the characteristic of "having pores" means that a subject includes a plurality of pores and, through a structure in which said pores are interconnected, gaseous and / or liquid fluids can pass from one side of the subject to the other.

[0030] In this specification, the separator has porous characteristics including a plurality of pores and acts as a porous ion-conducting barrier that blocks electrical contact between the cathode and the anode in an electrochemical device while allowing ions to pass through.

[0032] The present invention will be described in more detail below.

[0034] One embodiment of the present invention provides a self-supporting ceramic separator for an electrochemical device comprising a first inorganic particle, a second inorganic particle, and a polymer binder, wherein the first inorganic particle is plate-shaped and the aspect ratio of the first inorganic particle is 10 or more and 300 or less.

[0035] A self-supporting ceramic separator for an electrochemical device according to one embodiment of the present invention can suppress thermal shrinkage at high temperatures. In addition, a self-supporting ceramic separator for an electrochemical device according to one embodiment of the present invention can prevent transition metals leached from the anode from moving to the negative electrode surface, thereby improving the stability and battery life characteristics of the battery.

[0036] FIG. 1 is a schematic diagram of a self-standing ceramic separator for an electrochemical device according to one embodiment of the present invention. With reference to FIG. 1, a self-standing ceramic separator for an electrochemical device according to one embodiment of the present invention will be described in detail. FIG. 2 is a schematic diagram of an electrochemical device according to one embodiment of the present invention. With reference to FIG. 2, an electrochemical device according to one embodiment of the present invention will be described in detail.

[0037] According to one embodiment of the present invention, the self-supporting ceramic separator (100) for the electrochemical device does not include a porous polymer substrate. By not including the porous polymer substrate, the heat resistance of the separator is improved, and the separator shrinks at high temperatures, thereby preventing an electrical short circuit from occurring in the electrode.

[0038] According to one embodiment of the present invention, the separator (100) comprises a first inorganic particle, a second inorganic particle, and a polymer binder. As described above, by including the first inorganic particle, the second inorganic particle, and the polymer binder in the separator, the heat resistance of the separator is improved, and the separator shrinking at high temperatures can prevent an electrical short circuit from occurring in the electrode. Furthermore, pores can be formed inside the separator.

[0039] According to one embodiment of the present invention, the separator (100) may include a plurality of pores. Specifically, the separator may be a porous separator that includes a plurality of pores inside. As described above, by including a plurality of pores in the separator, it is possible to physically block the negative electrode and the positive electrode while allowing lithium ions to pass through and current to flow.

[0040] According to one embodiment of the present invention, the separator (100) may be formed by inorganic particles being bound by a polymer binder and accumulated within the membrane. The pores within the separator may originate from the interstitial volume, which is the empty space between the inorganic particles. Specifically, as described below, there may be differences in the structure and size of the pores depending on the difference in the shape and combination of the first inorganic particles and the second inorganic particles. Furthermore, depending on the difference in the structure and size of the pores, it may be possible to prevent transition metals leached from the anode from moving to the cathode face.

[0041] According to one embodiment of the present invention, the inorganic particles may comprise a first inorganic particle and a second inorganic particle. Non-limiting examples of the inorganic particles include BaTiO3, Pb(Zr,Ti)O3 (PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1, 0<y<1), Pb(Mg 1 / 3 Nb 2 / 3 Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc-tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), zeolite A, zeolite X, zeolite Y, etc., and may include one or more of these. Meanwhile, in addition to this, one or more plate-shaped inorganic particles selected from boron nitride (BN), boehmite, and kaolin may be included.

[0042] According to one embodiment of the present invention, the first inorganic particle is plate-shaped. As described above, since the first inorganic particle is plate-shaped, it is possible to form a dense laminated structure, thereby improving the durability of the separation membrane.

[0043] According to one embodiment of the present invention, the aspect ratio of the first inorganic particle is 10 or more and 300 or less. As described above, the first inorganic particle may be a plate-shaped inorganic particle with an aspect ratio of 10 or more and 300 or less. More specifically, the first inorganic particle may be a plate-shaped inorganic particle with an aspect ratio of 20 or more and 290 or less, 30 or more and 280 or less, 40 or more and 270 or less, 50 or more and 260 or less, 60 or more and 250 or less, 70 or more and 240 or less, 80 or more and 230 or less, 90 or more and 220 or less, 100 or more and 210 or less, 110 or more and 200 or less, 120 or more and 190 or less, 130 or more and 180 or less, 140 or more and 170 or less, or 150 or more and 160 or less. In this specification, the aspect ratio may be defined as [length in the major axis direction] / [width in the direction perpendicular to the major axis direction] of the plate-shaped inorganic particle. By controlling the aspect ratio of the first inorganic particles within the aforementioned range, the thickness of the coating layer can be made thin, and a dense stacked structure can be formed, thereby improving the durability of the separation membrane.

[0044] According to one embodiment of the present invention, one surface of the first inorganic particle and one surface of the separator may be arranged to face each other. As described above, since the first inorganic particle is a plate-shaped inorganic particle with an elongated shape in the long axis direction, the long axis direction is arranged to face one surface of the separator to form a dense stacked structure, thereby improving the durability of the separator. In addition, by forming a complex pore structure, the transition metal leached from the anode can be suppressed from moving to the cathode face.

[0045] According to one embodiment of the present invention, the structure may comprise: a first layer (110) in which the weight containing the first inorganic particle is greater than the weight containing the second inorganic particle; and a second layer (130) provided on one surface of the first layer, in which the weight containing the second inorganic particle is greater than the weight containing the first inorganic particle. Specifically, the first layer and the second layer may contain a mixture of the first inorganic particle and the second inorganic particle, but may be stacked by being divided into a first layer containing the first inorganic particle with a greater weight and a second layer containing the second inorganic particle with a greater weight. By stacking the first layer and the second layer as described above, the second layer adsorbs gas and transition metal, and the first layer prevents the transition metal adsorbed in the second layer from moving to the negative electrode face, thereby suppressing the occurrence of a battery short circuit.

[0046] According to one embodiment of the present invention, the opposite side of one surface of the first layer may be provided to face the cathode (300). FIG. 2 is a schematic diagram of an electrochemical element according to one embodiment of the present invention. Referring to FIG. 2, a first layer containing an excess amount of first inorganic particles or containing only first inorganic particles may be formed in contact with the cathode. As described above, the second layer is provided on one surface of the first layer, and the opposite side of one surface of the first layer is provided to face the cathode, thereby preventing the first layer from moving to the cathode face when a transition metal leached from the anode passes through the second layer without being adsorbed, thereby suppressing the occurrence of a battery short circuit.

[0047] According to one embodiment of the present invention, the first inorganic particle may comprise one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof. As described above, the first inorganic particle may be a plate-shaped inorganic particle. Specifically, boron nitride (BN) with a hexagonal crystal structure, boehmite (AlOOH) with a hexagonal crystal structure, and kaolin (Al2O2) 3· 2SiO 2· By including plate-shaped clay powder such as 2H2O, the first layer containing the first inorganic particles in a larger weight can be arranged to face one side of the separator to form a dense stacked structure. Furthermore, by forming a complex pore structure between the plate-shaped inorganic particles through the dense stacked structure, the transition metal leached from the anode can be suppressed from passing through the separator to the cathode face.

[0048] According to one embodiment of the present invention, the second inorganic particle may be a zeolite-based inorganic material. Specifically, the zeolite-based inorganic material may include one selected from the group consisting of zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5, beta-zeolite, ZSM-8, ZSM-11, and combinations thereof. The zeolite-based inorganic material may have a high specific surface area, and preferably, the zeolite-based inorganic material may be zeolite Y. As described above, by using a zeolite-based inorganic material as the second inorganic particle, the ability to adsorb gases and transition metals may be improved.

[0049] According to one embodiment of the present invention, the second inorganic particle may include a pore having a diameter of 0.5 nm or more and 0.9 nm or less. Specifically, the second inorganic particle may include a space inside the particle, and the diameter of the internal space may be 0.5 nm or more and 0.9 nm or less. Furthermore, the diameter of the pore may refer to the longest of the two points where a straight line passing through the interior of the pore meets the surface of the pore. More specifically, the pore of the second inorganic particle may have a diameter of 0.55 nm or more and 0.85 nm or less, 0.6 nm or more and 0.8 nm or less, or 0.65 nm or more and 0.75 nm or less. By controlling the diameter of the pore within the above-described range, the ability to adsorb gases generated in a lithium-ion battery, such as carbon monoxide (CO) or carbon dioxide (CO2), may be improved.

[0050] According to one embodiment of the present invention, the pores of the second inorganic particle may be substituted with metal ions. Specifically, the metal ions may be metal ions having an electronegativity equal to or lower than that of lithium ions. More specifically, the metal ions may be alkali metal ions. Preferably, the metal ions may be one selected from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and combinations thereof. By substituting the metal ions selected from the above into the pores of the second inorganic particle, the manganese ions contained in excess as a positive electrode active material are adsorbed, and the substituted lithium ions are leached into the electrolyte, thereby maintaining the electrical conductivity of the battery and reducing lithium tentrite, which is formed when manganese, a transition metal moving from the positive electrode to the negative electrode, accumulates on the negative electrode.

[0051] According to one embodiment of the present invention, the average particle size (D50) of the second inorganic particles may be 0.3 μm or more and 1 μm or less. Specifically, the average particle size (D50) of the second inorganic particles may be 0.4 μm or more and 0.9 μm or less, 0.5 μm or more and 0.8 μm or less, or 0.6 μm or more and 0.7 μm or less. By controlling the average particle size (D50) of the second inorganic particles within the above-described range, the phase separation rate and phase separation efficiency between the polymer binder and the second inorganic particles in a coating layer slurry, which is an emulsion containing the polymer binder dispersed in water, can be improved. Furthermore, if it is less than 0.3 μm, the dispersibility of the second inorganic particles in the slurry prepared for manufacturing the separation membrane may be reduced, and if it exceeds 1 μm, the thickness of the separation membrane formed may increase.

[0052] In this specification, "D50 particle size" refers to the particle size at the 50% point of the cumulative distribution of particle numbers according to particle size. The particle size can be measured using a laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to measure the difference in diffraction patterns according to particle size as the particles pass through a laser beam, thereby calculating the particle size distribution. The D50 particle size can be measured by calculating the particle diameter at the point that is 50% of the cumulative distribution of particle numbers according to particle size in the measuring device.

[0053] According to one embodiment of the present invention, the inorganic particles usable in the separator may be electrochemically stable. That is, the inorganic particles usable in one embodiment of the present invention are within the operating voltage range of the applied electrochemical element (e.g., Li / Li). + Oxidation and / or reduction reactions may not occur at a standard of 0 V to 5 V.

[0054] According to one embodiment of the present invention, the second layer may have a thickness of 1 μm or more and 3 μm or less. Specifically, the thickness of the second layer may be 1.1 μm or more and 2.9 μm or less, 1.2 μm or more and 2.8 μm or less, 1.3 μm or more and 2.7 μm or less, 1.4 μm or more and 2.6 μm or less, 1.5 μm or more and 2.5 μm or less, 1.6 μm or more and 2.4 μm or less, 1.7 μm or more and 2.3 μm or less, 1.8 μm or more and 2.2 μm or less, or 1.9 μm or more and 2.1 μm or less. As described above, since the average particle size (D50) of the second inorganic particles constituting the second layer is 1 μm or less, the thickness of the second layer can be controlled within the above-described range.

[0055] According to one embodiment of the present invention, the content of the first inorganic particles may be 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the separation membrane. Specifically, the content of the first inorganic particles may be 6 parts by weight or more and 9 parts by weight or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separation membrane. By controlling the content of the first inorganic particles within the above-described range, the heat resistance of the separation membrane can be improved, and the durability of the coating layer can be improved.

[0056] According to one embodiment of the present invention, the content of the second inorganic particles may be 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the separation membrane. Specifically, the content of the second inorganic particles may be 6 parts by weight or more and 9 parts by weight or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separation membrane. By controlling the content of the second inorganic particles within the above-described range, the heat resistance of the separation membrane can be improved, and the adsorption rate of gases and transition metals can be improved.

[0057] According to one embodiment of the present invention, the content of the polymer binder may be 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the separator. Specifically, the content of the polymer binder may be 6 parts by weight or more and 9 parts by weight or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separator. By controlling the content of the polymer binder within the above-described range, the porosity of the separator can be maintained, and the adhesive strength can be maintained even if the coating layer is wet by the electrolyte after the activation of the battery.

[0058] According to one embodiment of the present invention, the polymer binder may be in a particulate or non-particulate form. Specifically, as described below, the polymer binder may maintain a particulate shape without being dissolved by a dispersion medium or solvent, or the polymer binder may be dissolved by a dispersion medium or solvent and not maintain a particulate shape. As described above, by selecting the polymer binder to be in a particulate or non-particulate form, the mechanical properties and porosity of the coating layer can be controlled.

[0059] According to one embodiment of the present invention, the average particle size (D50) of the particulate polymer binder is 1.0 μm or less. Specifically, the average particle size (D50) of the particulate polymer binder particles may be 0.10 μm or more and 0.90 μm or less, 0.15 μm or more and 0.85 μm or less, 0.20 μm or more and 0.70 μm or less, 0.25 μm or more and 0.65 μm or less, 0.30 μm or more and 0.60 μm or less, 0.35 μm or more and 0.55 μm or less, or 0.40 μm or more and 0.50 μm or less. By controlling the average particle size (D50) of the particulate polymer binder within the range described above, the phase separation rate and phase separation efficiency between the particulate polymer binder and the inorganic particles in an inorganic slurry, which is an emulsion containing the particulate polymer binder dispersed in water, can be improved.

[0060] According to one embodiment of the present invention, the polymer binder may be an acrylic binder, a polyvinylidene binder, or a combination thereof.

[0061] According to one embodiment of the present invention, the polymer binder may comprise two or more types of polymer binders. As described above, by including two or more types of polymer binders in the polymer binder, the adhesion of the separator membrane can be improved, the porosity of the separator membrane can be improved, and the dry adhesion before the injection of the electrolyte and the wet adhesion after the injection of the electrolyte can be simultaneously improved.

[0062] According to one embodiment of the present invention, the polymer binder may include an acrylic binder. By using the acrylic binder, the porosity of the separator can be maintained, the adhesion between the electrode and the separator can be improved during the lamination process of the battery, thereby improving the ease of battery manufacturing and enabling a stable stacking process.

[0063] According to one embodiment of the present invention, the acrylic binder may be a polymer comprising a carboxylic acid ester as a repeating unit, preferably a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0064] According to one embodiment of the present invention, specific examples of the (meth)acrylic acid ester include: methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, ethylene glycol (meth)acrylate, di(meth)acrylate ethylene glycol, di(meth)acrylate propylene glycol. Examples include tri(meth)acrylate trimethylolpropane, tetra(meth)acrylate pentaerythritol, hexa(meth)acrylate dipentaerythritol, (meth)acrylate allyl, di(meth)acrylate ethylene, etc., and one or more selected from these may be used. Among these, it is preferable that one or more selected from (meth)acrylate methyl, (meth)acrylate ethyl, and (meth)acrylate 2-ethylhexyl, and it is particularly preferable that it be (meth)acrylate methyl.

[0065] According to one embodiment of the present invention, the acrylic-styrene copolymer may include an acrylic binder, and the acrylic binder may be of the polyacrylate type. For example, the binder may be one or more selected from the group consisting of styrene-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate-based polymers, and more specifically, may be a copolymer containing acrylate.

[0066] According to one embodiment of the present invention, the polymer binder may include a polyvinylidene-based binder. Specifically, according to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene. As described above, by selecting the polymer binder to be a polyvinylidene-based binder, the porosity of the separator can be maintained, and adhesion can be maintained even if the coating layer is wetted by the electrolyte after activation of the battery. Furthermore, the stiffness of the battery can be improved, and banding of the separator can be prevented.

[0067] According to one embodiment of the present invention, the polyvinylidene-based binder may be a water-based binder. Specifically, by selecting the polyvinylidene-based binder as a water-based binder, the manufacturing cost of the battery can be reduced by minimizing pollutants emitted during the manufacturing process of the separator.

[0068] According to one embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene-based binder having a hexafluoropropylene content of 1 weight% or more and 50 weight% or less. As described above, by selecting the second polymer binder particles as a polyvinylidene-based binder having a hexafluoropropylene content of 1 weight% or more and 50 weight% or less, the porosity of the separator can be maintained, and the adhesive strength can be maintained even if the coating layer is wet by the electrolyte after activation of the battery.

[0069] According to one embodiment of the present invention, the thickness of the separator may be 7 μm or more and 15 μm or less, but is not specifically limited thereto. Specifically, the thickness of the separator may be 8 μm or more and 14 μm or less, 9 μm or more and 13 μm or less, or 10 μm or more and 12 μm or less. The thickness can be adjusted to an appropriate range by a person skilled in the art in terms of heat resistance or electrical resistance. As described above, the plate-shaped first inorganic particles constituting the separator are arranged to face one surface of the separator to form a dense laminated structure, and since the average particle size (D50) of the second inorganic particles is 1 μm or less, the thickness of the separator can be adjusted to an appropriate range within the above-described range.

[0070] According to one embodiment of the present invention, the thickness of the second layer and / or the separator, etc., can be measured by applying a contact-type thickness gauge. For example, the VL-50S-B of Mitutoyo can be used as the contact-type thickness gauge.

[0071] According to one embodiment of the present invention, the air permeability of the separation membrane may be 170 sec / 100cc or less. Specifically, the air permeability of the separation membrane may be 100 sec / 100cc or more and 170 sec / 100cc or less, 110 sec / 100cc or more and 160 sec / 100cc or less, 120 sec / 100cc or more and 150 sec / 100cc or less, or 130 sec / 100cc or more and 140 sec / 100cc or less. As described above, excellent air permeability may be exhibited because the inorganic particles are plate-shaped or have a small average particle size (D50).

[0072] According to one embodiment of the present invention, the resistance of the separator may be 0.6 Ω or more and 1.2 Ω or less. Specifically, the resistance of the separator may be 0.7 Ω or more and 1.1 Ω or less, or 0.8 Ω or more and 1.0 Ω or less. As described above, it is believed that the resistance value of the separator is low because the inorganic particles are plate-shaped or have a small average particle size (D50).

[0073] According to one embodiment of the present invention, the dielectric breakdown voltage of the separator may be 3700V or higher. Specifically, the dielectric breakdown voltage of the separator may be 3700V or higher and 5000V or lower, 3800V or higher and 4900V or lower, 3900V or higher and 4800V or lower, 4000V or higher and 4700V or lower, 4100V or higher and 4600V or lower, 4200V or higher and 4500V or lower, or 4300V or higher and 4400V or lower. As described above, since the inorganic particles are plate-shaped or have a small average particle size (D50), the dielectric breakdown voltage of the separator is high, and it can be seen that the dielectric breakdown voltage is excellent.

[0074] According to one embodiment of the present invention, the porosity of the separator may be 30 volume% or more. Specifically, the porosity of the separator may be 30 volume% or more and 70 volume% or less, 32 volume% or more and 68 volume% or less, 34 volume% or more and 66 volume% or less, 36 volume% or more and 64 volume% or less, 38 volume% or more and 62 volume% or less, 40 volume% or more and 60 volume% or less, 42 volume% or more and 58 volume% or less, 44 volume% or more and 56 volume% or less, 46 volume% or more and 54 volume% or less, or 48 volume% or more and 52 volume% or less. By controlling the porosity of the separator within the above-described range, the movement of ions in the separator can be maintained, and an increase in the resistance of the separator can be prevented. Specifically, if the porosity is 70 volume% or less, mechanical properties capable of withstanding the press process for bonding with the electrode can be secured, and the surface opening ratio does not become too high, making it suitable for securing adhesion. Meanwhile, if the porosity is 30 volume% or more, it is advantageous in terms of ion permeability.

[0075] In this specification, “porosity” refers to the ratio of the volume occupied by pores to the total volume, and is expressed in volume % as a unit; it may be used interchangeably with terms such as porosity and porosity.

[0076] In this specification, porosity corresponds to a value obtained by subtracting the volume converted into weight and density of each component of the separation membrane from the volume calculated in terms of the thickness, width, and length of the separation membrane.

[0077] In one embodiment of the present invention, the porosity and pore size of the separation membrane can be measured by the BET 6-point method using the nitrogen gas adsorption flow method with scanning electron microscope (SEM) images, a mercury porosimeter, a capillary flow pore distribution analyzer, or a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini). In this case, it may be advantageous to use a capillary flow pore distribution analyzer.

[0078] According to one embodiment of the present invention, the method for forming the separation membrane is as follows. First, a polymer solution or polymer emulsion is prepared by dissolving a polymer binder in a suitable solvent or dispersing it in a dispersion medium. It is preferable that the solvent or dispersion medium has a solubility index similar to that of the polymer binder to be used and has a low boiling point. This is to facilitate uniform mixing and subsequent removal of the solvent or dispersion medium. Non-limiting examples of usable solvents or dispersion media include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0079] Next, a first inorganic particle is added and dispersed in the first polymer solution or first polymer emulsion prepared to prepare a first inorganic slurry. According to one embodiment of the present invention, the content ratio of the first inorganic particle to the polymer binder is as described above and is appropriately adjusted considering the thickness, pore size, and porosity of the separation membrane of the present invention finally prepared.

[0080] Next, the first inorganic slurry prepared above is applied to at least one side of the prepared PET release film and dried. The method of applying the first inorganic slurry to the surface of the PET release film is not specifically limited to any one method, and conventional methods known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, or a combination thereof may be used.

[0081] Next, a second inorganic particle is added and dispersed into a second polymer solution or a second polymer emulsion prepared in the same manner to prepare a second inorganic slurry. According to one embodiment of the present invention, the content ratio of the second inorganic particle to the polymer binder is as described above and is appropriately adjusted considering the thickness, pore size, and porosity of the separation membrane of the present invention finally prepared.

[0082] Next, the second inorganic slurry prepared above is applied onto a first layer containing the first inorganic particles applied above and dried. The method of applying the second inorganic slurry to the surface of the first layer is not specifically limited to any one method, and conventional methods known in the art may be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, or a combination thereof may be used.

[0083] The above drying process appropriately sets temperature and time conditions to minimize the occurrence of surface defects in the separator. During the drying, drying auxiliary devices such as a drying oven or hot air may be used within an appropriate range.

[0084] After the above drying process, the PET release film can be removed to manufacture the separator.

[0085] According to one embodiment of the present invention, a polymer binder, namely a first polymer binder and a second polymer binder, may be dispersed in water, which is a suitable dispersion medium, together with a wetting agent to prepare a polymer emulsion, thereby providing a first and / or second inorganic slurry. The wetting agent may be present in the first and / or second inorganic slurry as one or more wetting agents in an amount of 0 to 5 parts, preferably 0 to 3 parts, per 100 parts of water. A surfactant may be provided as the wetting agent, but the wetting agent may also include a non-surfactant. In some embodiments, the wetting agent may be an organic solvent. When any wetting agent is present, the powder material(s) are uniformly dispersed in an aqueous dispersion of a polyvinylidene-based binder. Useful wetting agents include, but are not limited to, ionic and nonionic surfactants such as the TRITON series (Dow) and PLURONIC series (BASF), BYK-346 (BYK Additives), and NMP, DMSO, and acetone, and include but are not limited to organic liquids compatible with aqueous dispersions. As described above, by dispersing a polymer binder together with a wetting agent in water, which is a suitable dispersion medium, to prepare a polymer emulsion and thereby providing a first and / or second inorganic slurry, contaminants generated during the manufacturing process can be minimized.

[0086] According to one embodiment of the present invention, the separator (100) is interposed between the cathode (300) and the anode (500) and is manufactured into an electrochemical device by a lamination process in which heat and / or pressure is applied to bond them. In one embodiment of the present invention, the lamination process may be performed by a roll press device comprising a pair of pressure rollers. That is, the cathode, the separator, and the anode may be sequentially stacked and placed between the pressure rollers to achieve interlayer bonding. At this time, the lamination process may be performed by a hot pressing method.

[0088] One embodiment of the present invention provides an electrochemical device comprising: an anode (300); a cathode (500); and a separator (100) interposed between the anode and the cathode.

[0089] An electrochemical device according to one embodiment of the present invention comprises a first inorganic particle capable of preventing transition metals leached from the anode from moving to the cathode face by forming a plate-like, dense stacked structure, and a second inorganic particle capable of adsorbing gas and transition metals having a high specific surface area, and by including a separator without a porous polymer substrate, heat resistance and durability are improved, and the stability and lifespan characteristics of the battery can be improved.

[0090] In the present invention, the electrochemical device is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept that encompasses primary batteries and secondary batteries. In this specification, the secondary battery is capable of charging and discharging and refers to a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. The lithium secondary battery uses lithium ions as an ion conductor, and examples include a non-aqueous electrolyte secondary battery containing a liquid electrolyte, an all-solid-state battery containing a solid electrolyte, a lithium polymer battery containing a gel polymer electrolyte, and a lithium metal battery using lithium metal as a negative electrode, but are not limited thereto.

[0091] According to one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer comprising a positive electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. The positive electrode active material is a layered compound such as a lithium manganese complex oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-xLithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 ~ 0.3); chemical formula LiMn 1-x It may include a lithium manganese complex oxide represented by MxO2 (where M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which some of the Li in the chemical formula is substituted with alkaline earth metal ions; a disulfide compound; and one or more of Fe2(MoO4)3.

[0092] According to one embodiment of the present invention, the cathode comprises a cathode current collector and a cathode active material layer comprising a cathode active material, a conductive material, and a binder resin on at least one surface of the current collector. The cathode comprises, as the cathode active material, carbon such as lithium metal oxide, non-graphitizable carbon, and graphite-based carbon; Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1), Sn x Me 1-x Me y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; 리튬 금속; 리튬 합금; 규소계 합금; 주석계 합금; SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, 및 Bi2O5등의 금속 산화물; 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료; 티타늄 산화물 중 선택된 1종 또는 2종 이상의 혼합물을 포함할 수 있다.

[0093] According to one embodiment of the present invention, the conductive material may be, for example, any one selected from the group consisting of graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whiskers, conductive metal oxide, activated carbon, and polyphenylene derivative, or a mixture of two or more of these conductive materials. More specifically, it may be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, Denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more of these conductive materials.

[0094] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used.

[0095] According to one embodiment of the present invention, the binder resin may be a polymer commonly used in the industry for electrodes. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include acetatepropionate), cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose, but are not limited thereto.

[0096] According to one embodiment of the present invention, the anode slurry for manufacturing the anode active material layer may include a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (N-methylpyrrolidone, ADC-01, LG Chem).

[0097] According to one embodiment of the present invention, the content of the dispersant included in the anode slurry may be greater than 0 parts by weight and less than or equal to 0.5 parts by weight per 100 parts by weight of the anode slurry. Specifically, the content of the dispersant included in the anode slurry may be greater than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of the anode slurry.

[0098] According to one embodiment of the present invention, the cathode slurry for manufacturing the cathode active material layer may include a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei Corporation, Japan).

[0099] According to one embodiment of the present invention, the content of the dispersant included in the cathode slurry may be greater than 0 parts by weight and less than or equal to 0.5 parts by weight per 100 parts by weight of the cathode slurry. Specifically, the content of the dispersant included in the cathode slurry may be greater than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of the cathode slurry.

[0100] According to one embodiment of the present invention, an electrochemical element prepared as above can be placed in a suitable case and an electrolyte injected to manufacture a battery.

[0101] According to one embodiment of the present invention, the electrolyte is A + B - As a salt with a structure similar to that of, A + is Li + , Na + , K +It includes alkali metal cations such as or ions composed of combinations thereof, and B - is PF6 - , BF4 - , Cl - , Br - , I - , ClO4 - , AsF6 - , CH3CO2 - , CF3SO3 - , N(CF3SO2) 2- , C(CF2SO2) 3- Salts containing anions such as or combinations thereof are dissolved or dissociated in organic solvents composed 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), ethylmethyl carbonate (EMC), gamma butyrolactone (γ-butyrolactone), or mixtures thereof, but are not limited thereto.

[0102] One embodiment of the present invention provides a battery module including a battery including the electrochemical element as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool that moves by receiving power from a battery motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0103] Hereinafter, the present invention will be described in detail with reference to examples to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention is not to be interpreted as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those with average knowledge in the art.

[0105] <Example 1>

[0106] Hexagonal boron nitride (hBN), synthesized with an aspect ratio of 50 as a plate-shaped first inorganic particle, and polyacrylic acid (PAA), a dispersant, were added to NMP (N-Methyl-2-pyrrolidone), a solvent, and dispersed with a sonicator for about 30 minutes to prepare an oil-based slurry.

[0107] A first polymer binder solution comprising an acrylic water-dispersible emulsion (Toyo Ink, CSB130) and a surfactant (FC-4430, Kemis) as polymer binders was added to the above oil-based slurry and dispersed with a sonicator for about 30 minutes to prepare a first inorganic slurry.

[0108] Subsequently, the first inorganic slurry was applied to one side of a PET release film and dried. The weight ratio of the first inorganic particles to the polymer binder was set to 9:1.

[0109] Zeolite Y (SAR, Silicon Aluminum ratio 1.5 or higher) was added to water and dispersed as a second inorganic particle, and basket milling was performed at 1400 rpm and 1800 rpm for 10 minutes and 50 minutes, respectively, to prepare an aqueous slurry with reduced particle size (D50: 1 μm or less).

[0110] A second polymer binder solution comprising an acrylic water-dispersible emulsion (Toyo Ink, CSB140) and a surfactant (BYK, BYK348) as polymer binders was added to the above water-based slurry 1 hour before coating, and a second inorganic slurry was prepared after 30 minutes of sonication.

[0111] Subsequently, the second inorganic slurry was applied to the surface of the first layer containing the first inorganic particles and dried. The weight ratio of the second inorganic particles to the polymer binder was set to 92:8.

[0112] The dispersion was applied to the surface of the second layer containing the second inorganic particles using a doctor blade by a bar coating method and dried with a heat gun at 50°C.

[0113] Afterwards, the above PET release film was removed to manufacture a separator with a total thickness of 13 μm.

[0115] <Example 2>

[0116] A separation membrane was prepared in the same manner as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particle in Example 1 was 200.

[0118] <Comparative Example 1>

[0119] A separation membrane with a thickness of 14 μm was prepared in the same manner as in Example 1, except that a first layer containing plate-shaped first inorganic particles was omitted and a second inorganic particle, zeolite Y, was added to prepare it as a single layer.

[0121] <Comparative Example 2>

[0122] A separation membrane with a thickness of 11 μm was prepared in the same manner as in Example 1, except that hexagonal boron nitride (hBN), which is a plate-shaped first inorganic particle, was added to prepare a single layer without a second layer containing a second inorganic particle in Example 1.

[0124] <Comparative Example 3>

[0125] A separation membrane with a thickness of 14 μm was prepared in the same manner as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particle in Example 1 was less than 10.

[0127] <Comparative Example 4>

[0128] A separation membrane with a thickness of 12 μm was prepared in the same manner as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particle in Example 1 was greater than 300.

[0130] Manufacture of Electrochemical Devices

[0131] 1) Manufacture of the anode

[0132] Cathode active material (LiNi 0.8 Mn 0.1 Co 0.1 O2), a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chem), and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for an anode active material layer with a concentration of 50 wt% of the components excluding water. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to manufacture an anode having an anode active material layer (thickness 120 μm).

[0133] 2) Preparation of the cathode

[0134] Graphite (a blend of natural graphite and artificial graphite), a conductive material (carbon black), a dispersant (Polyvinylpyrrolidone, Junsei, Japan), and a binder resin (a mixture of PVDF-HFP and PVDF) were mixed with water in a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a negative electrode active material layer with a concentration of 50 wt% of the components excluding water. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to manufacture a negative electrode having a negative electrode active material layer (thickness 120 μm).

[0135] 3) Lamination Process

[0136] An electrode assembly was obtained by interposing the separator of the example and comparative example between the cathode and anode manufactured above, laminating them, and performing a lamination process. The lamination process was performed using a hot press for 10 seconds under conditions of 70°C and 5.2 MPa.

[0138] <Experimental Example 1: Air Permeability of Separator>

[0139] The air permeability (air time, Gurley) of the membranes in the examples and comparative examples was measured according to the ASTM D-2873 method. The Gurley value was measured using a Toyoseiki Gurley-type Densometer (No. 158) in accordance with the Japanese Industrial Standard Gurley (JIS Gurlye) measurement method. The air permeability value was obtained when 100 ml of air entered the membrane at a pressure of 12.2 in H2O, 1 in 2 It was expressed as the time (in seconds) taken to pass through the cross-section, i.e., the air passage time.

[0141] <Experimental Example 2: Resistance of the Separator>

[0142] A coin cell was manufactured by interposing the separator of the example and comparative example between SUS materials. As the electrolyte for the coin cell, ethylene carbonate and ethyl methyl carbonate were mixed in a 1:2 (volume ratio), and LiPF6 was added at a concentration of 1 M. For each coin cell, the resistance was measured using an analysis device (VMP3, Bio logic science instrument) through electrochemical impedance spectroscopic analysis results at 25 ℃ under conditions of amplitude 10 mV and scan range 0.1 Hz to 1 MHz.

[0144] <Experimental Example 3: Dielectric Breakdown Voltage of Separator>

[0145] Separator samples of the prepared examples and comparative examples were placed between aluminum jigs (upper jig diameter 30 mm, lower jig 50x100 mm), and the voltage at which a short circuit occurred was measured using a Hi-pot tester. At this time, the measurement conditions were set to DC, current 0.5 mA, and voltage step-up 100 V / s (up to 3 kV).

[0147] <Experimental Example 4: Performance Retention Rate of Electrochemical Devices>

[0148] In order to evaluate the lifespan of electrochemical devices manufactured including the separators of the examples and comparative examples, each electrochemical device was charged to 4.35V at 0.33C and discharged to 2.0V at 0.33C for 500 cycles, and the initial capacity and remaining capacity were measured.

[0150] <Experimental Example 5: Gas Generation Amount of Electrochemical Device>

[0151] To measure the amount of gas generated by electrochemical devices manufactured including the separators of the examples and comparative examples, each electrochemical device was charged and discharged once at 25°C under 0.1C / 0.1C conditions to proceed with formation, and the amount of gas generated was measured. To measure the amount of gas generated by the degraded cell, the cell evaluated up to 500 cycles as in Experimental Example 4 was completely discharged to 2.0V at 0.33C, and then the amount of gas was measured.

[0153] <Experimental Example 6: Transition Metal Elution Amount from Electrochemical Device>

[0154] To measure the amount of cathode transition metal leaching from electrochemical devices manufactured including the separators of the examples and comparative examples, a charge-discharge test was performed 500 times by forming the devices to an SOC of 30%, discharging them under conditions of a discharge current density of 0.33C and a discharge voltage of 2.0V, and charging them under conditions of a charge current density of 0.33C, a charge voltage of 4.35V, and CC-CV (Constant Current-Constant Voltage). After 500 cycles, the amount of transition metal leached to the cathode surface was measured.

[0156] Membrane properties Evaluation of electrochemical devices Thickness (μm) Air per 100cc Resistance (Ω) Dielectric breakdown voltage (V) Performance retention rate (% / 0.33C 500 cycles) Gas generation amount (μl) Cathode-facing ICP analysis (ppm / 500 cycle) Ni Co Mn Comparative Example 1 14 120 0.9 3650 85 120 70 <5 510 Comparative Example 2 11 140 1.4 1670 73 550 170 <5 860 Comparative Example 3 14 125 1.0 3430 80 230 100 <5 680 Comparative Example 4 12 140 1.7 2150 74 210 35 <5 290 Example 1 13 130 1.0 4360 83 220 53 <5 460 Example 2 13 133 1.1 4120 89 215 42 <5 340

[0157] Referring to Table 1 above, in Examples 1 and 2 according to one embodiment of the present invention, by-products that were not adsorbed by the functional inorganic particles of the second layer passed through the plate-shaped inorganic layer of the first layer and did not reach the cathode surface, and it was confirmed that the amount of transition metal leaching was significantly reduced on the cathode surface of the electrochemical device degraded by 500 cycle discharges. With the same effect, the performance retention rate of the electrochemical device and the amount of gas generated were also confirmed.

[0159] In this regard, Comparative Example 1 is a self-supporting ceramic separator composed solely of second inorganic particles capable of adsorbing by-products generated during the degradation of an electrochemical device. When discharged for 500 cycles, it shows a result in which the amount of transition metal leaching from the cathode surface of the degraded electrochemical device is reduced compared to a general separator. Comparative Example 2 is a separator composed solely of plate-shaped inorganic particles, which are the first inorganic particles. Although it was expected that the more dense assembly of inorganic particles would complicate the pathways of transition metal ions and reduce by-products accumulating on the cathode surface, it is inferior to Comparative Example 1. As in Comparative Example 3, when the aspect ratio of the plate-shaped inorganic particles is too low (AR < 10), the expected effect of using plate-shaped inorganic particles is negligible, and it exhibited inferior properties in terms of the amount of transition metal leaching from the cathode surface, the performance retention rate of the electrochemical device, and the amount of gas generated. As in Comparative Example 4, when the aspect ratio of plate-shaped inorganic particles is too large (AR > 300), it was confirmed that the plate-shaped inorganic particles have a strong tendency to hinder the durability of the separator, resulting in a significantly lower dielectric breakdown voltage and a low level of performance retention rate for the electrochemical device.

[0161] A self-supporting ceramic separator for an electrochemical device according to one embodiment of the present invention includes a functional inorganic material and a plate-shaped inorganic material, thereby preventing gas adsorption and the accumulation of by-products on the cathode surface during the degradation of the electrochemical device, and thus improving the performance of the electrochemical device. Explanation of the symbols

[0163] 100: Self-supporting ceramic separator for electrochemical devices 110: 1st floor 130: 2nd floor 300: Cathode 500: Anode

Claims

Claim 1 A self-supporting ceramic separator for an electrochemical device comprising a first inorganic particle, a second inorganic particle, and a polymer binder, wherein the first inorganic particle is plate-shaped, the second inorganic particle is a zeolite-based inorganic, the aspect ratio of the first inorganic particle is 10 or more and 300 or less, the second inorganic particle includes pores having a diameter of 0.5 nm or more and 0.9 nm or less, and the pores of the second inorganic particle are substituted with metal ions, and a first layer in which the weight containing the first inorganic particle is greater than the weight containing the second inorganic particle; and a second layer provided on one surface of the first layer, wherein the weight containing the second inorganic particle is greater than the weight containing the first inorganic particle. Claim 2 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein one surface of the first inorganic particle and one surface of the separator are arranged to face each other. Claim 3 delete Claim 4 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the opposite side of one side of the first layer is provided to face the cathode. Claim 5 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the first inorganic particle comprises one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof. Claim 6 delete Claim 7 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the average particle size (D50) of the second inorganic particle is 1 μm or less. Claim 8 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the thickness of the second layer is 1 μm or more and 3 μm or less. Claim 9 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the content of the first inorganic particle is 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the separator. Claim 10 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the polymer binder is an acrylic binder, a polyvinylidene binder, or a combination thereof. Claim 11 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the thickness of the separator is 7 μm or more and 15 μm or less. Claim 12 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the air permeability of the separator is 170 sec / 100cc or less. Claim 13 A self-supporting ceramic separator for an electrochemical device according to claim 1, wherein the resistance of the separator is 0.6 Ω or more and 1.2 Ω or less. Claim 14 An electrochemical device comprising: an anode; a cathode; and a separator interposed between the anode and the cathode, wherein the separator is any one of claims 1, 2, 4, 5 and 7 to 13.

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