Self-supporting ceramic separation membrane for electrochemical elements, and electrochemical elements containing the same

Abstract

The present invention relates to a self-supporting ceramic separation membrane for an electrochemical element and an electrochemical element including the same. Specifically, by appropriately adjusting the content and arrangement of plate-shaped first inorganic particles and second inorganic particles which are zeolite-based inorganic substances, the heat resistance of the separation membrane is improved, electrical short circuit between electrodes is prevented to improve the safety of the battery, and the present invention relates to a self-supporting ceramic separation membrane for an electrochemical element exhibiting high cell life characteristics and an electrochemical element including the same.

Description

[Technical Field]

[0001] This application claims the benefits as of the filing date of Patent Application No. 10-2023-0051554, filed with the Korean Intellectual Property Office on April 19, 2023, and all of its contents are included in this application.

[0002] The present invention relates to a self-supporting ceramic separation membrane for electrochemical elements and an electrochemical element containing the same. Specifically, it relates to a self-supporting ceramic separation membrane for electrochemical elements that exhibits improved heat resistance and high cell lifetime characteristics by containing first inorganic particles and second inorganic particles, and an electrochemical element containing the same. [Background technology]

[0003] Among the components of an electrochemical element, the separation membrane is located between the positive and negative electrodes and contains a porous polymer substrate. Its role is to isolate the positive and negative electrodes, prevent electrical short circuits between the two electrodes, and allow electrolytes and ions to pass through. Although the separation membrane itself does not participate in the electrochemical reaction, its physical properties, such as wettability to the electrolyte, degree of porosity, and thermal shrinkage rate, affect the performance and safety of the electrochemical element.

[0004] Therefore, in order to enhance the physical properties of the separation membrane, various methods have been attempted to change the physical properties of the coating layer by adding a coating layer to a porous polymer substrate and adding various substances to the coating layer. For example, inorganic substances may be added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic substances or hydrates may be added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0005] The separation membrane can be bonded to the electrode through a lamination process, and a polymer binder can be added to the coating layer composition of the separation membrane to ensure adhesion between the electrode and the separation membrane.

[0006] On the other hand, polyolefin resins, which are widely used as porous polymer substrates for electrochemical elements, have a problem in that when exposed to high temperatures, they shrink, causing the positive and negative electrodes to come into contact, resulting in an electrical short circuit between the two electrodes, generating heat, and causing thermal runaway due to the decomposition reaction between the electrolyte and the active material.

[0007] Therefore, there was a need for research on self-supporting ceramic separator membranes that could improve heat resistance and durability, prevent electrical short circuits between electrodes, and enhance battery safety and battery life characteristics by appropriately combining inorganic particles without the need for polyolefin-based resins, which are porous polymer substrates. [Overview of the project] [Problems that the invention aims to solve]

[0008] The technical problem that the present invention aims to solve is to provide a self-supporting ceramic separation membrane for an electrochemical element, and an electrochemical element containing the same, which includes first inorganic particles that form a plate-like, dense laminated structure to prevent transition metals eluted from the positive electrode from moving to the negative electrode surface, and second inorganic particles that have a high specific surface area and are capable of gas adsorption and transition metal adsorption, while also providing improved heat resistance and durability, and improved battery stability and battery life characteristics, due to a configuration without a porous polymer substrate.

[0009] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0010] One embodiment of the present invention provides a self-supporting ceramic separation membrane for an electrochemical element, comprising first inorganic particles, second inorganic particles, and a polymer binder, wherein the first inorganic particles are plate-shaped and the aspect ratio of the first inorganic particles is between 10 and 300.

[0011] According to one embodiment of the present invention, the separation membrane can be arranged such that one surface of the first inorganic particles faces one surface of the separation membrane.

[0012] According to one embodiment of the present invention, the separation membrane may include a first layer in which the weight of the first inorganic particles is higher than the weight of the second inorganic particles; and a second layer provided on one surface of the first layer, in which the weight of the second inorganic particles is higher than the weight of the first inorganic particles.

[0013] According to one embodiment of the present invention, the opposite surface of one surface of the first layer can be configured to face the negative electrode.

[0014] According to one embodiment of the present invention, the first inorganic particles may include one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof.

[0015] According to one embodiment of the present invention, the second inorganic particles are zeolite-based inorganic substances, the second inorganic particles include voids having a diameter of 0.5 nm or more and 0.9 nm or less, and the voids of the second inorganic particles can be substituted with metal ions.

[0016] According to one embodiment of the present invention, the average particle diameter (D50) of the second inorganic particles can be 1 μm or less.

[0017] According to one embodiment of the present invention, the thickness of the second layer can be 1 μm or more and 3 μm or less.

[0018] According to one embodiment of the present invention, the content of the first inorganic particles can be 5 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the coating layer.

[0019] According to one embodiment of the present invention, the polymer binder can be an acrylic binder, a polyvinylidene binder, or a combination thereof.

[0020] According to one embodiment of the present invention, the thickness of the separation membrane can be 7 μm or more and 15 μm or less.

[0021] According to one embodiment of the present invention, the permeability of the separation membrane may be 170 sec / 100 cc or less.

[0022] According to one embodiment of the present invention, the resistance of the separation membrane may be 0.6 Ω or more and 1.2 Ω or less.

[0023] One embodiment of the present invention provides an electrochemical element comprising a positive electrode; a negative electrode; and a separation membrane interposed between the positive electrode and the negative electrode. [Effects of the Invention]

[0024] A self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention can suppress thermal shrinkage at high temperatures.

[0025] A self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention can prevent transition metals eluted from the positive electrode from moving to the negative electrode surface, thereby improving the stability and lifespan characteristics of the battery. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic diagram of a self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention.

[0027] [Figure 2] This is a schematic diagram of an electrochemical element according to one embodiment of the present invention. [Modes for carrying out the invention]

[0028] In this specification, when a part is said to "include" a component, unless otherwise stated, this means that it may include other components rather than excluding them.

[0029] In this specification, "A and / or B" means "A and B, or A or B."

[0030] In this specification, when we say that a component is "placed on top of" another component, this does not exclude the possibility of other components being placed in between, unless otherwise specified.

[0031] In this specification, the characteristic of "having pores" means that the object contains a plurality of pores, and the structure is such that gaseous and / or liquid fluids can pass from one side of the object to the other.

[0032] In this specification, the separation membrane has porous properties, including numerous pores, and plays the role of a porous ion-conducting barrier, allowing ions to pass through while blocking electrical contact between the negative and positive electrodes using an electrochemical element.

[0033] The present invention will be described in more detail below.

[0034] One embodiment of the present invention provides a self-supporting ceramic separation membrane for an electrochemical element, comprising first inorganic particles, second inorganic particles, and a polymer binder, wherein the first inorganic particles are plate-shaped and the aspect ratio of the first inorganic particles is between 10 and 300.

[0035] A self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention can suppress thermal shrinkage at high temperatures. Furthermore, a self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention can prevent transition metals eluted from the positive electrode from moving to the negative electrode surface, thereby improving the stability and battery life characteristics of the battery.

[0036] Figure 1 is a schematic diagram of a self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention. Referring to Figure 1, the self-supporting ceramic separation membrane for an electrochemical element, which is one embodiment of the present invention, will be described in detail. Figure 2 is a schematic diagram of an electrochemical element according to one embodiment of the present invention. Referring to Figure 2, the electrochemical element, which is one embodiment of the present invention, will be described in detail.

[0037] According to one embodiment of the present invention, the self-supporting ceramic separation membrane 100 for the electrochemical element does not contain a porous polymer substrate. By not including the porous polymer substrate in the self-supporting ceramic separation membrane for the electrochemical element, the heat resistance of the separation membrane can be improved, and it is possible to prevent the separation membrane from shrinking at high temperatures and causing an electrical short circuit between the electrodes.

[0038] According to one embodiment of the present invention, the separation membrane 100 includes first inorganic particles, second inorganic particles, and a polymer binder. As described above, by including first inorganic particles, second inorganic particles, and a polymer binder in the separation membrane, the heat resistance of the separation membrane can be improved, and it is possible to prevent the separation membrane from shrinking at high temperatures and causing an electrical short circuit between the electrodes. Furthermore, pores can be formed inside the separation membrane.

[0039] According to one embodiment of the present invention, the separation membrane 100 may include a plurality of pores. Specifically, the separation membrane may be a porous separation membrane containing a plurality of pores inside. As described above, by including a plurality of pores in the separation membrane, lithium ions can pass through and current can flow while physically separating the negative electrode and the positive electrode.

[0040] According to one embodiment of the present invention, the separation membrane 100 may be formed by inorganic particles being bound together by a polymer binder and accumulating within the membrane. The pores inside the separation membrane may be due to interstitial volume, which is the empty space between the inorganic particles. Specifically, as will be described later, there may be differences in the structure and size of the pores depending on the differences in the morphology and combination of the first inorganic particles and the second inorganic particles. Furthermore, the differences in the structure and size of the pores can prevent the transition metal eluted from the positive electrode from moving to the negative electrode side.

[0041] According to one embodiment of the present invention, the inorganic particles may include first inorganic particles and second inorganic particles. 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 one or more of these may be included. On the other hand, in addition to the above, one or more plate-shaped inorganic particles from boron nitride (BN), boehmite, and kaolin may be included.

[0042] According to one embodiment of the present invention, the first inorganic particles are plate-shaped. As described above, since the first inorganic particles are 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 to 300. As described above, the first inorganic particle is a plate-shaped inorganic particle, and its aspect ratio may be 10 to 300. More specifically, the first inorganic particle is a plate-shaped inorganic particle, and its aspect ratio may be 20 to 290, 30 to 280, 40 to 270, 50 to 260, 60 to 250, 70 to 240, 80 to 230, 90 to 220, 100 to 210, 110 to 200, 120 to 190, 130 to 180, 140 to 170, or 150 to 160. In this specification, the aspect ratio can be defined as the [length in the long axis direction] / [width in the direction perpendicular to the long axis direction] of the plate-shaped inorganic particle. By adjusting the aspect ratio of the first inorganic particle within the range described above, the thickness of the coating layer can be made thinner, enabling the formation of a dense laminated structure and improving the durability of the separation film.

[0044] According to one embodiment of the present invention, the separation membrane can be arranged such that one surface of the first inorganic particles faces one surface of the separation membrane. As described above, the first inorganic particles are plate-shaped inorganic particles and have a long shape in the longitudinal direction. By arranging them so that the longitudinal direction faces one surface of the separation membrane, a dense laminated structure can be formed, thereby improving the durability of the separation membrane. Furthermore, by forming a complex porous structure, it is possible to suppress the migration of transition metals eluted from the positive electrode to the negative electrode surface.

[0045] According to one embodiment of the present invention, the separation membrane may include a first layer 110 in which the weight containing the first inorganic particles is higher than the weight containing the second inorganic particles; and a second layer 130 provided on one surface of the first layer in which the weight containing the second inorganic particles is higher than the weight containing the first inorganic particles. Specifically, the first and second inorganic particles may be mixed in the first and second layers, but they may be laminated separately as a first layer containing a higher weight of the first inorganic particles and a second layer containing a higher weight of the second inorganic particles. As described above, by laminating the first and second layers separately, the second layer adsorbs gas and transition metals, and the first layer prevents the transition metals adsorbed in the second layer from moving to the negative electrode side, thereby suppressing the occurrence of battery short circuits.

[0046] According to one embodiment of the present invention, the opposite side of one surface of the first layer may be configured to face the negative electrode 300. Figure 2 is a schematic diagram of an electrochemical element according to one embodiment of the present invention. Referring to Figure 2, the separation membrane may be formed by a first layer containing an excess of first inorganic particles, or containing only first inorganic particles, in contact with the negative electrode. As described above, by providing the second layer on one surface of the first layer, and configuring the opposite side of one surface of the first layer to face the negative electrode, the first layer can prevent transition metals eluted from the positive electrode from moving to the negative electrode side when they pass through without being adsorbed by the second layer, thereby suppressing the occurrence of a battery short circuit.

[0047] According to one embodiment of the present invention, the first inorganic particles may include one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof. As described above, the first inorganic particles may be plate-type inorganic particles. Specifically, hexagonal crystalline boron nitride (BN), hexagonal crystalline boehmite (AlOOH), kaolin (Al2OOH) 3· 2SiO 2·By including plate-shaped clay powder such as 2H2O, the first layer containing the first inorganic particles in a higher weight can be positioned to face one surface of the separation membrane, thereby forming a dense laminated structure. Furthermore, by forming a complex pore structure between the plate-shaped inorganic particles through the dense laminated structure, it is possible to suppress the movement of transition metals eluted from the positive electrode through the separation membrane to the negative electrode side.

[0048] According to one embodiment of the present invention, the second inorganic particles 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 particles, the ability to adsorb gases and transition metals can be improved.

[0049] According to one embodiment of the present invention, the second inorganic particle may contain a void having a diameter of 0.5 nm or more and 0.9 nm or less. Specifically, the second inorganic particle contains 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 void may mean the longest of the lengths between two points where a straight line passing through the inside of the void intersects the surface of the void. More specifically, the void 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 adjusting the diameter of the void within the above range, the ability to adsorb gases generated from lithium-ion batteries, such as carbon monoxide (CO) or carbon dioxide (CO2), can be improved.

[0050] According to one embodiment of the present invention, the voids in the second inorganic particles can be replaced with metal ions. Specifically, the metal ions may be metal ions having the same or lower electronegativity as 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 replacing the voids in the second inorganic particles with metal ions selected from the above, the excess manganese ions contained in the positive electrode active material can be adsorbed, and the replaced lithium ions can dissolve into the electrolyte, thereby maintaining the electrical conductivity of the battery and reducing lithium dendrites that are generated when manganese, a transition metal that moves 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 adjusting the average particle size (D50) of the second inorganic particles within the above range, the phase separation rate and phase separation efficiency between the polymer binder and the second inorganic particles can be improved in a coating layer slurry which is an emulsion containing the polymer binder dispersed in water. Furthermore, if the average particle size is less than 0.3 μm, the dispersibility of the second inorganic particles may decrease in the slurry prepared for the production of a separation membrane, and if it exceeds 1 μm, the thickness of the formed separation membrane may increase.

[0052] In this specification, the "D50 particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the particle size. The particle size can be measured using the 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 (for example, Microtrac S3500). When the particles pass through the laser beam, the difference in the diffraction pattern according to the particle size is measured to calculate the particle size distribution. The D50 particle size can be measured by calculating the particle diameter at the point where the cumulative distribution of the number of particles according to the particle size in the measuring device reaches 50%.

[0053] According to one embodiment of the present invention, the inorganic particles that can be used for the separation membrane may be electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention do not undergo oxidation and / or reduction reactions within the operating voltage range of the applied electrochemical device (for example, 0V to 5V based on Li / Li + as a reference).

[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 adjusted 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 less, or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separation membrane. By adjusting the content of the first inorganic particles within the above 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 less, or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separation membrane. By adjusting the content of the second inorganic particles within the above 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 separation membrane. Specifically, the content of the polymer binder may be 6 parts by weight or more and 9 parts by weight or less, or 7 parts by weight or more and 8 parts by weight or less per 100 parts by weight of the separation membrane. By adjusting the content of the polymer binder within the above range, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated.

[0058] According to one embodiment of the present invention, the polymer binder may be particulate or non-particulate. Specifically, as will be described later, the polymer binder may maintain its particle shape without dissolving in the dispersion medium or solvent, or it may dissolve in the dispersion medium or solvent and not maintain its particle shape. As described above, the mechanical properties and porosity of the coating layer can be adjusted by selecting whether the polymer binder is particulate or non-particulate.

[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 adjusting the average particle size (D50) of the particulate polymer binder within the above range, the phase separation rate and phase separation efficiency between the particulate polymer binder and inorganic particles can be improved in an inorganic slurry which is an emulsion containing the particulate polymer binder dispersed in water.

[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 contain two or more polymer binders. As described above, by including two or more polymer binders in the polymer binder, the adhesive strength of the separation membrane can be improved, the porosity of the separation membrane can be improved, and both the dry adhesive strength (before electrolyte injection) and the wet adhesive strength (after electrolyte injection) 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 separation membrane can be maintained, the adhesion between the electrodes and the separation membrane can be improved in the battery lamination process, thereby improving the ease of battery manufacturing and enabling stable implementation of the stacking process.

[0063] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and is 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, and (meth)acrylate. Examples include decyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, ethylene glycol methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, allyl methacrylate, and ethyl dimethacrylate, and one or more of these can be selected. Of these, one or more selected from methyl methacrylate, ethyl methacrylate, and 2-ethylhexyl methacrylate is preferred, and methyl methacrylate is particularly preferred.

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

[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 a polyvinylidene-based binder as the polymer binder, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated. Furthermore, the stiffness of the battery can be improved, and banding of the separation membrane can be prevented.

[0067] According to one embodiment of the present invention, the polyvinylidene-based binder may be an aqueous binder. Specifically, by selecting an aqueous binder for the polyvinylidene-based binder, the amount of contaminants discharged from the manufacturing process of the separation membrane can be minimized, thereby reducing the manufacturing cost of the battery.

[0068] According to one embodiment of the present invention, the polyvinylidene binder may be a polyvinylidene binder having a hexafluoropropylene content of 1% to 50% by weight. As described above, by selecting a polyvinylidene binder having a hexafluoropropylene content of 1% to 50% by weight for the second polymer binder particles, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated.

[0069] According to one embodiment of the present invention, the thickness of the separation membrane may be 7 μm or more and 15 μm or less, but is not particularly limited thereto. Specifically, the thickness of the separation membrane 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 those skilled in the art from the standpoint of heat resistance and electrical resistance. As described above, the plate-shaped first inorganic particles constituting the separation membrane are arranged so as to face one surface of the separation membrane, forming a dense laminated structure, and the average particle size (D50) of the second inorganic particles is 1 μm or less, so the thickness of the separation membrane can be adjusted to an appropriate range within the above range.

[0070] According to one embodiment of the present invention, the thickness of the second layer and / or the separation membrane can be measured using a contact-type thickness measuring instrument. For example, the VL-50S-B from Mitutoyo can be used as the contact-type thickness measuring instrument.

[0071] According to one embodiment of the present invention, the permeability of the separation membrane may be 170 sec / 100 cc or less. Specifically, the permeability of the separation membrane may be 100 sec / 100 cc or more and 170 sec / 100 cc or less, 110 sec / 100 cc or more and 160 sec / 100 cc or less, 120 sec / 100 cc or more and 150 sec / 100 cc or less, or 130 sec / 100 cc or more and 140 sec / 100 cc or less. As described above, it can be confirmed that the permeability is excellent 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 separation membrane may be 0.6 Ω or more and 1.2 Ω or less. Specifically, the resistance of the separation membrane 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 thought that the resistance value of the separation membrane appears 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 separation membrane may be 3700V or higher. Specifically, the dielectric breakdown voltage of the separation membrane may be 3700V to 5000V, 3800V to 4900V, 3900V to 4800V, 4000V to 4700V, 4100V to 4600V, 4200V to 4500V, or 4300V to 4400V. As described above, because the inorganic particles are plate-shaped or have a small average particle size (D50), the dielectric breakdown voltage of the separation membrane is high, and it is clear that it has excellent dielectric strength.

[0074] According to one embodiment of the present invention, the porosity of the separation membrane may be 30 volume% or more. Specifically, the porosity of the separation membrane may be 30 volume% to 70 volume%, 32 volume% to 68 volume%, 34 volume% to 66 volume%, 36 volume% to 64 volume%, 38 volume% to 62 volume%, 40 volume% to 60 volume%, 42 volume% to 58 volume%, 44 volume% to 56 volume%, 46 volume% to 54 volume%, or 48 volume% to 52 volume%. By adjusting the porosity of the separation membrane within the above range, it is possible to maintain ion movement in the separation membrane and prevent an increase in the resistance of the separation membrane. Specifically, a porosity of 70 volume% or less ensures mechanical properties that can withstand the pressing process for bonding with electrodes, and is suitable for ensuring adhesive strength without the surface opening ratio becoming too high. On the other hand, a porosity of 30 volume% or more is advantageous from the viewpoint of ion permeability.

[0075] In this specification, "porosity" refers to the ratio of the volume occupied by pores to the total volume, and its unit is volume %. It can be used interchangeably with terms such as void ratio and porosity.

[0076] In this specification, porosity corresponds to the subtraction value obtained by subtracting the volume of each component of the separation membrane converted to weight and density from the volume calculated in terms of 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 BET6 method using nitrogen gas adsorption flow, employing scanning electron microscope (SEM) images, a mercury porosimeter, a capillary flow porometer, or a porosimetry analyzer (Bell Japan Inc., Belsorp-II mini). In this case, using a capillary flow porometer may be advantageous.

[0078] According to one embodiment of the present invention, a 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. The solvent or dispersion medium is preferably one that has a similar solubility index to the polymer binder to be used and 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 mediums include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof.

[0079] Next, the first inorganic particles are added to and dispersed in the manufactured first polymer solution or first polymer emulsion to produce the first inorganic slurry. According to one embodiment of the present invention, the content ratio of the first inorganic particles 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 that is finally produced.

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

[0081] Next, a second inorganic slurry is produced by adding and dispersing second inorganic particles into a second polymer solution or second polymer emulsion produced by the same method. According to one embodiment of the present invention, the content ratio of the second inorganic particles 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 that is finally produced.

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

[0083] The drying process involves appropriately setting temperature and time conditions to minimize the occurrence of surface defects in the separation membrane. Within an appropriate range, drying aids such as drying ovens or hot air can be used for the drying process.

[0084] After the drying process, the PET release film can be removed to produce the separation membrane.

[0085] According to one embodiment of the present invention, a polymeric binder, i.e., a first polymeric binder and a second polymeric binder, can be dispersed together with a wetting agent in water, which is a suitable dispersion medium, to produce a polymeric emulsion and provide a first and / or second inorganic slurry. The wetting agent is one or more wetting agents, preferably 0 to 3 parts per 100 parts of water. Surfactants can be provided as wetting agents, but wetting agents may also include non-surfactants. In some embodiments, the wetting agent may be an organic solvent. In the presence of any wetting agent, (multiple) powder materials are uniformly dispersed in an aqueous dispersion of polyvinylidene-based binders. Useful wetting agents include, but are not limited to, ionic and nonionic surfactants, e.g., the Triton series (Dow) and Pluronic series (BASF), BYK-346 (BYK Additives), and NMP, DMSO, and acetone, as well as 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 produce a polymer emulsion and providing a first and / or second inorganic slurry, the amount of contaminants generated from the manufacturing process can be minimized.

[0086] According to one embodiment of the present invention, the separation membrane 100 is interposed between the negative electrode 300 and the positive electrode 500 and manufactured as an electrochemical element by a lamination process in which heat and / or pressure is applied to bond them together. In one embodiment of the present invention, the lamination process can be carried out by a roll press device including a pair of pressure rollers. That is, the negative electrode, the separation membrane, and the positive electrode can be sequentially laminated and placed between the pressure rollers to achieve interlayer bonding. In this case, the lamination process can be carried out by a hot pressurization method.

[0087] One embodiment of the present invention provides an electrochemical element comprising a positive electrode 500; a negative electrode 300; and a separation membrane 100 interposed between the positive electrode and the negative electrode.

[0088] An electrochemical element according to one embodiment of the present invention includes first inorganic particles that form a plate-like, dense laminated structure to prevent transition metals eluted from the positive electrode from moving to the negative electrode surface, and second inorganic particles that have a high specific surface area and are capable of gas adsorption and transition metal adsorption. However, by including a separation membrane without a porous polymer substrate, heat resistance and durability are improved, and the stability and battery life characteristics of the battery can be improved.

[0089] In the present invention, the electrochemical element is a device that converts chemical energy into electrical energy by an electrochemical reaction, and comprises a primary battery and a secondary battery (Secondary This is a comprehensive concept encompassing batteries. In this specification, the term "secondary battery" means a rechargeable and dischargeable battery, such as a lithium secondary battery, nickel-cadmium battery, nickel-metal hydride battery, etc. The term "lithium secondary battery" uses lithium ions as an ion conductor and includes, but is not limited to, non-aqueous electrolyte secondary batteries containing a liquid electrolyte, all-solid-state batteries containing a solid electrolyte, lithium polymer batteries containing a gel polymer electrolyte, and lithium metal batteries using lithium metal as the negative electrode.

[0090] According to one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector, comprising a positive electrode active material, a conductive material, and a binder resin. The positive electrode active material is a layered compound such as lithium manganese composite oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented as O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 1-x M x Lithium manganese composite oxides represented as O2 (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 part of the Li in the chemical formula is replaced with an alkaline earth metal ion; disulfide compounds; and may contain one or more of the following mixtures: Fe2(MoO4)3.

[0091] According to one embodiment of the present invention, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer on at least one surface of the current collector, comprising a negative electrode active material, a conductive material, and a binder resin. The negative electrode comprises carbon such as lithium metal oxide, non-graphitizable carbon, and graphite-based carbon as the negative electrode active material; 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, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8), etc. metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; may include one or more mixtures selected from titanium oxides.

[0092] 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 whisker, 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 or a mixture of two or more of these conductive materials selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide.

[0093] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. For example, stainless steel, copper, aluminum, nickel, titanium, fired carbon, or those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used.

[0094] According to one embodiment of the present invention, the binder resin can be a polymer commonly used in electrodes in the industry. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include, but are not limited to, acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methylcellulose.

[0095] According to one embodiment of the present invention, the cathode slurry for producing the cathode active material layer may contain a dispersant, and the dispersant may be a pyrrolidone compound. Specifically, it may be N-methylpyrrolidone (ADC-01, LG Chemical Co., Ltd.).

[0096] According to one embodiment of the present invention, the content of the dispersant in the positive electrode slurry may be more than 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant in the positive electrode slurry may be more than 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the positive electrode slurry.

[0097] According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may contain a dispersant, and the dispersant may be a polypyrrolidone compound. Specifically, the dispersant may be polyvinylpyrrolidone (Junsei Corporation).

[0098] According to one embodiment of the present invention, the content of the dispersant contained in the negative electrode slurry may be more than 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the negative electrode slurry. Specifically, the content of the dispersant contained in the negative electrode slurry may be more than 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the negative electrode slurry.

[0099] According to one embodiment of the present invention, the electrochemical element prepared as described above can be placed in a suitable case and an electrolyte solution injected to manufacture a battery.

[0100] According to one embodiment of the present invention, the electrolyte is A + B - A salt with a structure like this, + is Li + kaNa + , K + It contains alkali metal cations such as, or ions consisting of combinations thereof, B - PF6 - BF4- Cl - , Br - , I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - , N(CF3SO2) 2- , C(CF2SO2) 3- Salts containing anions such as those listed above, or ions consisting of combinations thereof, may be dissolved or dissociated in organic solvents consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone (γ-butyrolactone), or mixtures thereof, but are not limited to these.

[0101] One embodiment of the present invention provides a battery module including a battery containing the electrochemical element as a unit battery, 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 powered by a battery-powered motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric motorcycles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems. [Examples]

[0102] The present invention will be described in detail below with reference to examples. However, the examples of the present invention can be modified into various different forms, and the scope of the present invention should not be construed as being limited to the examples described below. The examples herein are provided to give a more complete explanation of the present invention to a person of average skill in the art.

[0103] <Example 1> As the first inorganic particles, which are plate-like in shape, synthesized hexagonal boron nitride (hBN) with an aspect ratio of 50, and polyacrylic acid (PAA) as a dispersant were added to the solvent NMP (N-methyl-2-pyrrolidone) and dispersed with a sonicator for about 30 minutes to prepare an oil-based slurry.

[0104] A first polymer binder solution containing an acrylic water-dispersible emulsion (Toyo Ink, CSB130) and a surfactant (FC-4430, Kemis) was added to the oil-based slurry and dispersed in a sonicator for approximately 30 minutes to prepare a first inorganic slurry.

[0105] Subsequently, the first inorganic slurry was applied to one surface of the PET release film and dried. The weight ratio of the first inorganic particles to the polymer binder was 9:1.

[0106] As a second inorganic particle, zeolite Y (SAR, silicon-aluminum ratio of 1.5 or higher) was added to water and dispersed. Basket milling was then 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).

[0107] As a polymer binder, a second polymer binder solution containing an acrylic water-dispersible emulsion (Toyo Ink, CSB140) and a surfactant (BYK, BYK348) was added to the aqueous slurry one hour before coating, and sonication was performed for 30 minutes to prepare the second inorganic slurry.

[0108] 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 92:8.

[0109] 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 then dried with a heat gun at 50°C.

[0110] Subsequently, the PET release film was removed to produce a separation membrane with a total thickness of 13 μm.

[0111] <Example 2> In Example 1, the separation membrane was manufactured using the same method as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particles was 200.

[0112] <Comparative Example 1> In the above-mentioned Example 1, a separation membrane with a thickness of 14 μm was manufactured in the same manner as in Example 1, except that the first layer containing the plate-shaped first inorganic particles was omitted, and the second inorganic particle, zeolite Y, was added to form a single layer.

[0113] <Comparative Example 2> In the above-mentioned Example 1, a separation membrane with a thickness of 11 μm was manufactured using the same method as in Example 1, except that a plate-shaped first inorganic particle, hexagonal boron nitride (hBN), was added to form a single layer without the second layer containing the second inorganic particle.

[0114] <Comparative Example 3> In Example 1, a separation membrane with a thickness of 14 μm was manufactured using the same method as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particles was less than 10.

[0115] <Comparative Example 4> A separation membrane with a thickness of 12 μm was manufactured using the same method as in Example 1, except that the aspect ratio of the plate-shaped first inorganic particles was greater than 300.

[0116] <Manufacturing of electrochemical elements> 1) Manufacturing of the positive electrode Cathode active material (LiNi 0.8 Mn 0.1 Co 0.1 A slurry for the positive electrode active material layer was prepared by mixing O2), a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical Co., Ltd.), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and removing the water to obtain a slurry of the remaining components at a concentration of 50 wt%. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to produce a positive electrode having a positive electrode active material layer (thickness 120 μm).

[0117] 2) Manufacturing of the negative electrode A slurry for the negative electrode active material layer was prepared by mixing graphite (a blend of natural and artificial graphite), a conductive material (carbon black), a dispersant (polyvinylpyrrolidone, manufactured by Junsei Corporation), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and then removing the water to obtain a slurry of the remaining components at a concentration of 50 wt%. Next, the slurry was applied to the surface of a copper thin film (10 μm thick) and dried to produce a negative electrode having a negative electrode active material layer (120 μm thick).

[0118] 3) Lamination process The separation films of the examples and comparative examples were interposed between the manufactured negative electrode and positive electrode and laminated, and an electrode assembly was obtained by performing a lamination process. The lamination process was carried out using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0119] <Experimental Example 1: Air permeability of separation membrane> The permeability (permeability time, Gurley) of the separation membranes in the examples and comparative examples was measured according to the ASTM D-2873 method. The Gurley value was measured using a Gurley type densometer (No. 158) from Toyoseiki Co., Ltd., in accordance with the Japanese Industrial Standard (JIS) Gurley measurement method. The permeability value was calculated by passing 100 ml of air through the separation membrane at a pressure of 12.2 in H2O for 1 in 2 This is expressed as the time (in seconds) it takes for air to pass through the cross-section, i.e., the permeability time.

[0120] <Experimental Example 2: Resistance of Separation Membrane> Coin cells were manufactured by interposing the separation membranes of the examples and comparative examples between SUS (stainless steel) layers. The electrolyte for the coin cells was a mixture of ethylene carbonate and ethyl methyl carbonate in a 1:2 (volume ratio), with LiPF6 added at a concentration of 1 M. The resistance of each coin cell was measured using an analytical instrument (VMP3, Bio Logic Science Instrument) under conditions of 25°C, amplitude of 10 mV, and scan range of 0.1 Hz to 1 MHz, through electrochemical impedance spectroscopy.

[0121] <Experimental Example 3: Dielectric Breakdown Voltage of Separation Film> The prepared separation membrane samples for the examples and comparative examples were placed between aluminum fixtures (upper fixture diameter 30 mm, lower fixture 50 x 100 mm), and the voltage at which a short circuit occurred was measured using a Hi-pot tester. The measurement conditions were set to DC, current 0.5 mA, and voltage boost 100 V / s (maximum 3 kV).

[0122] <Experimental Example 4: Performance Retention Rate of Electrochemical Elements> To evaluate the lifespan of electrochemical elements manufactured with the separation films of the examples and comparative examples, each electrochemical element was charged to 4.35V at 0.33C and discharged to 2.0V at 0.33C for 500 cycles, and the initial and remaining capacities were measured.

[0123] <Experimental Example 5: Gas Generation Amount of Electrochemical Device> To measure the gas generation amount of electrochemical elements manufactured with the separation membranes of the examples and comparative examples, each electrochemical element was subjected to one charge-discharge cycle at 25°C under conditions of 0.1C / 0.1C, and the amount of gas generated was measured while undergoing formation. To measure the gas generation amount of degraded cells, cells evaluated up to 500 cycles as in Experimental Example 4 were completely discharged to 2.0V at 0.33C, and then the amount of gas was measured.

[0124] <Experimental Example 6: Transition Metal Leaching Amount from Electrochemical Devices> To measure the amount of transition metal leached from the negative electrode of electrochemical elements manufactured with the separation membranes of the examples and comparative examples, the elements were subjected to formation at 30% SOC. A charge-discharge test was then conducted 500 times, discharging at a discharge current density of 0.33C and a discharge voltage of 2.0V, and charging at a charge current density of 0.33C, a charge voltage of 4.35V, and CC-CV (constant current-constant voltage) conditions. After 500 cycles, the amount of transition metal leached onto the negative electrode surface was measured.

[0125] [Table 1]

[0126] Referring to Table 1, in Examples 1 and 2 according to one embodiment of the present invention, by-products that could not be adsorbed by the functional inorganic particles of the second layer also increasingly failed to reach the negative electrode surface through the plate-shaped inorganic layer, which is the first layer. As a result, a significant decrease in the amount of transition metal elution at the negative electrode surface of the electrochemical element that had deteriorated after 500 cycles of discharge was confirmed. The same effect was observed in the improved performance retention rate of the electrochemical element and the reduced amount of gas generated.

[0127] In contrast, Comparative Example 1 is a self-supporting ceramic separation membrane consisting only of second inorganic particles capable of adsorbing by-products generated during the degradation of an electrochemical element. It shows that the amount of transition metal elution on the negative electrode side of an electrochemical element that has been degraded by 500 cycles of discharge is reduced compared to a general separation membrane. Comparative Example 2 is a separation membrane consisting only of plate-shaped inorganic particles, which are the first inorganic particles. It was expected that a denser inorganic assembly would be possible, complicating the pathways of transition metal ions and reducing the amount of by-products accumulated on the negative electrode side, but it was at an inferior level compared 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 insufficient, and it showed inferior properties in terms of the amount of transition metal elution on the negative electrode side, the performance retention rate of the electrochemical element, and the amount of gas generated. As shown in Comparative Example 4, when the aspect ratio of the plate-shaped inorganic particles is too large (AR > 300), the plate-shaped inorganic particles strongly impede the durability of the separation membrane, resulting in a significantly lower dielectric breakdown voltage and a low performance retention rate for the electrochemical element.

[0128] A self-supporting ceramic separation membrane for an electrochemical element according to one embodiment of the present invention includes a functional inorganic material and a plate-type inorganic material, thereby preventing gas adsorption and the accumulation of by-products on the anode side during degradation of the electrochemical element, and thus improving the performance of the electrochemical element. [Explanation of Symbols]

[0129] 100: Self-supporting ceramic separation membrane for electrochemical elements 110: 1st layer 130: 2nd layer 300: Negative electrode 500: Positive electrode

Claims

1. It comprises first inorganic particles, second inorganic particles, and a polymer binder. The first inorganic particle is plate-shaped, The second inorganic particles are zeolite-based inorganic materials, and the second inorganic particles contain voids having a diameter of 0.5 nm or more and 0.9 nm or less. The voids in the second inorganic particle are replaced with metal ions. A self-supporting ceramic separation membrane for electrochemical elements, wherein the aspect ratio of the first inorganic particle is between 10 and 300.

2. A self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein one surface of the first inorganic particles and one surface of the separation membrane are arranged to face each other.

3. A first layer in which the weight of the first inorganic particles is higher than the weight of the second inorganic particles, A second layer provided on one surface of the first layer, wherein the weight of the second inorganic particles is higher than the weight of the first inorganic particles, A self-supporting ceramic separation membrane for an electrochemical element according to claim 1, comprising:

4. The self-supporting ceramic separator membrane for an electrochemical element according to claim 3, wherein the opposite side of one surface of the first layer is configured to face the negative electrode. 。

5. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the first inorganic particle comprises one selected from the group consisting of boron nitride, boehmite, kaolin, and combinations thereof.

6. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the average particle size (D50) of the second inorganic particles is 1 μm or less.

7. The self-supporting ceramic separation membrane for an electrochemical element according to claim 3, wherein the thickness of the second layer is 1 μm or more and 3 μm or less.

8. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the content of the first inorganic particles is 5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the separation membrane.

9. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the polymer binder is an acrylic binder, a polyvinylidene binder, or a combination thereof.

10. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the thickness of the separation membrane is 7 μm or more and 15 μm or less.

11. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the permeability of the separation membrane is 170 sec / 100 cc or less.

12. The self-supporting ceramic separation membrane for an electrochemical element according to claim 1, wherein the resistance of the separation membrane is 0.6 Ω or more and 1.2 Ω or less.

13. An electrochemical element comprising a positive electrode, a negative electrode, and a separation membrane according to any one of claims 1 to 12 interposed between the positive electrode and the negative electrode.

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