Separation membrane for electrochemical elements and electrochemical elements containing the same

Abstract

The present invention relates to a separation membrane for an electrochemical element and an electrochemical element including the same. Specifically, the present invention relates to a separation membrane for an electrochemical element and an electrochemical element including the same, in which heat resistance is improved and the resistance of a battery can be reduced by providing an adhesive layer containing a polyvinyl acetate-based resin on a coating layer.

Description

[Technical Field]

[0001] This application claims all the benefits of the filing date of Korean Patent Application No. 10-2023-0026495, filed with the Korean Intellectual Property Office on February 28, 2023, and the benefits of the filing date of Korean Patent Application No. 10-2024-0007842, filed with the Korean Intellectual Property Office on January 18, 2024, and the entire content thereof is included in this application. The present invention relates to a separation membrane for an electrochemical element and an electrochemical element including the same, and more specifically, to a separation membrane for an electrochemical element and an electrochemical element including the same, which can improve heat resistance and reduce battery resistance by providing an adhesive layer containing a polyvinyl acetate resin on a coating layer. [Background technology]

[0002] Among the components of an electrochemical element, the separation membrane is placed 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.

[0003] Therefore, in order to enhance the physical properties of the separation membrane, a coating layer is added to a porous polymer substrate, and various methods are being attempted to change the physical properties of the coating layer by adding various substances to the coating layer. For example, inorganic substances are added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic substances or hydrates are added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0004] The separation membrane can be bonded to the electrode by a lamination process, and a binder resin can be added to the slurry for the coating layer of the separation membrane to ensure adhesion between the electrode and the separation membrane.

[0005] On the other hand, existing separation membranes used in medium- and large-sized batteries such as EVs (Electric Vehicles) and ESSs (Energy Storage Systems) achieve adhesion through a coating method using humidified phase separation for the lamination and stacking assembly process. For this reason, a high content of PVdF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) is required. However, separation membranes containing a high content of PVdF-HFP have problems such as reduced heat resistance, an increase in particle size in the slurry containing the binder, making it difficult to thin the separation membrane and thus difficult to secure energy density. In addition, in the case of oil-based binders, since they are soluble in the electrolyte, if an excessive amount of binder is dissolved in the electrolyte, the viscosity of the electrolyte increases, the ionic conductivity decreases, resistance increases, and battery performance deteriorates.

[0006] In the case of a separation membrane with a coating layer containing a high concentration of inorganic particles, the high concentration of inorganic material provides excellent heat resistance, making it possible to thin the separation membrane. However, in the case of a separation membrane containing such a high concentration of inorganic material in the coating layer, there is no adhesive layer on the surface, which presents a problem in that lamination becomes difficult during the assembly process of manufacturing batteries.

[0007] Therefore, research was needed on separation films that could reduce resistance while maintaining adhesion and could be made into thin films. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The technical problem that this invention aims to solve is to overcome the problems of the prior art, to achieve a low viscosity of the electrolyte in a battery, improve battery performance, and to provide a separation membrane for an electrochemical element and an electrochemical element containing the same, by making the separation membrane thin, providing an adhesive layer containing a polyvinyl acetate resin on the coating layer, and adjusting the amount of binder dissolved in the electrolyte by adjusting the content of the polyvinyl acetate resin in the coating layer. This makes it possible to achieve a low viscosity of the electrolyte in the battery, improve battery performance, and make the separation membrane thinner.

[0009] However, the problems that this invention aims to solve are not limited to those mentioned above, and other problems not mentioned can 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 includes a porous polymer substrate; a coating layer provided on at least one surface of the porous polymer substrate and containing a first polymer binder and inorganic particles; and an adhesive layer provided on the coating layer and containing a second polymer binder containing a polyvinyl acetate resin, wherein the content of the second polymer binder per unit area of ​​the adhesive layer is 0 g / m². 2 Ultra, 1.5g / m 2 The following separation membrane for electrochemical elements is provided. Here, the area refers to the plane on the separation membrane as viewed from a viewpoint perpendicular to the substrate, the coating layer, and the adhesive layer.

[0011] According to one embodiment of the present invention, the content of the second polymer binder per unit area of ​​the adhesive layer is 0.1 g / m². 2 More than 1.4g / m 2 The following is also acceptable.

[0012] According to one embodiment of the present invention, the content of the inorganic particles in the coating layer may be 90 parts by weight or more per 100 parts by weight of the coating layer.

[0013] According to one embodiment of the present invention, the second polymer binder may be in the form of particles.

[0014] According to one embodiment of the present invention, the adhesive layer may further include a third polymer binder containing a polyvinylidene-based binder.

[0015] According to one embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene.

[0016] According to one embodiment of the present invention, the weight ratio of the second polymer binder to the third polymer binder in the adhesive layer may be 99:1 to 50:50.

[0017] According to one embodiment of the present invention, the thickness of the coating layer may be greater than 0 μm and less than or equal to 2.0 μm.

[0018] According to one embodiment of the present invention, the resistance of the separation film for the electrochemical element may be 0.8 Ω or less.

[0019] One embodiment of the present invention provides an electrochemical element comprising a positive electrode; a negative electrode; a separation membrane; and an electrolyte, wherein the separation membrane is the aforementioned separation membrane for an electrochemical element interposed between the positive electrode and the negative electrode.

[0020] According to one embodiment of the present invention, the solubility of the second polymer binder in the electrolyte may be 50 (w / w) or more and 80 (w / w) or less at room temperature. [Effects of the Invention]

[0021] An electrochemical element separation film according to one embodiment of the present invention can be made into a thin film to improve the energy density of the battery, and a coating layer containing a high content of inorganic particles, equipped with an adhesive layer, can achieve adhesive strength during the battery manufacturing process.

[0022] An electrochemical element according to one embodiment of the present invention can lower the viscosity of the electrolyte by adjusting the solubility of the polymer binder contained in the adhesive layer in the electrolyte, thereby improving the ionic conductivity of the battery while simultaneously lowering the surface resistance of the battery. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram of a separation membrane for an electrochemical device according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a separation membrane for an electrochemical device according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of a separation membrane for an electrochemical device according to one embodiment of the present invention. [Figure 4] This is a schematic diagram of a separation membrane for an electrochemical device according to one embodiment of the present invention. [Figure 5] This is a schematic diagram of an electrochemical element according to one embodiment of the present invention. [Modes for carrying out the invention]

[0024] Hereinafter, various embodiments of the present invention will be described in detail so that a person of ordinary skill in the art to which the present invention pertains can easily implement the present invention. However, these are merely examples provided for illustrative purposes and the scope of the present invention is not limited by the following.

[0025] Unless otherwise specified, detailed descriptions defining or embodying embodiments are applicable to all inventions and are not limited to descriptions of a particular invention. That is, this disclosure also represents combinations of embodiments disclosed separately. Furthermore, unless otherwise expressly stated, a singular form encompasses multiple forms across the detailed descriptions and appended claims.

[0026] In this specification, when a part is described as "containing" a component, this means, unless otherwise stated, that it may contain other components rather than excluding them. However, unless otherwise explicitly stated, terms such as "constituted" or "constituted" include "substantially constituted" and "constituted."

[0027] As used herein, the term "essentially contained" means "containing 70% or more," preferably "containing 80% or more," and most preferably "containing 90% or more." When referring to the amount of a component in a mixture of substances, the percentage is a weight percentage relative to the total weight of each component in the mixture. As an example, a substance that essentially contains polyethylene contains polyethylene in an amount of at least 70% by weight relative to the total weight of the substance.

[0028] Furthermore, the terms “about” and “substantially” as used herein are used when manufacturing and material tolerances inherent in the described circumstances are given, or are used in substantially the same sense, and are used to prevent misuse of this specification, which contains precise or absolute figures for understanding this specification.

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

[0030] In this specification, when a component is described as being "on top of" another component, unless otherwise specified, this does not preclude other components from being placed in between, but rather means that other components may be placed further on top of it. However, unless otherwise explicitly stated, "on top of" means "directly on top of," that is, it includes situations in which no other components are placed further on top of it.

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

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

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

[0034] One embodiment of the present invention comprises a porous polymer substrate 110; a coating layer 130 provided on at least one surface of the porous polymer substrate 110 and containing a first polymer binder 131 (not shown) and inorganic particles 133 (not shown); and an adhesive layer 150 provided on the coating layer 130 and containing a second polymer binder 151 containing a polyvinyl acetate (PVAc) resin, wherein the content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 is 0 g / m². 2 Super 1.5g / m 2 The following separation membrane 100 for electrochemical elements is provided.

[0035] The separation film 100 for electrochemical elements according to one embodiment of the present invention can be made into a thin film to improve the energy density of the battery, and by having an adhesive layer 150, the coating layer 130 containing a high content of inorganic particles can achieve adhesive strength during the battery manufacturing process.

[0036] Figure 1 is a schematic diagram of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. Figure 2 is a schematic diagram of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. Specifically, Figure 1 is a schematic diagram of a separation membrane 100 for an electrochemical element in which a coating layer 130 and an adhesive layer 150 are provided on one surface, and Figure 2 is a schematic diagram of a separation membrane 100 for an electrochemical element in which a coating layer 130 and an adhesive layer 150 are provided on both sides. The separation membrane 100 for an electrochemical element according to one embodiment of the present invention will be described in detail with reference to Figures 1 and 2.

[0037] According to one embodiment of the present invention, the separation membrane 100 for the electrochemical element includes a porous polymer substrate 110. As described above, by including the porous polymer substrate 110 in the separation membrane 100 for the electrochemical element, lithium ions can pass through while electrical contact is blocked, and a shutdown function can be realized at an appropriate temperature.

[0038] According to one embodiment of the present invention, the porous polymer substrate 110 may be manufactured using a polyolefin resin as the base resin. Examples of polyolefin resins include polyethylene, polypropylene, and polypentene, and one or more of these may be included. A porous separation membrane, i.e., one with numerous pores, manufactured using such a polyolefin resin as the base resin is advantageous in terms of providing a shutdown function at an appropriate temperature.

[0039] According to one embodiment of the present invention, the weight-average molecular weight of the polyolefin resin may be between 500,000 and 1,500,000. By adjusting the weight-average molecular weight of the polyolefin resin within the aforementioned range, the compressive resistance of the separation membrane can be improved. Furthermore, when different types of polyolefin resins are mixed and used, or when a separation membrane is formed with a multilayer structure made of different types of polyolefin resins, the weight-average molecular weight of the polyolefin resins can be calculated by adding the weight-average molecular weights based on the content ratio of each polyolefin resin.

[0040] In this specification, "weight-average molecular weight (Mw)" can be measured by gel permeation chromatography (GPC: PLGPC220, Agilent Technologies), and the measurement conditions can be set as follows: - Column: PL Olexis (Polymer Laboratories) - Solvent: TCB (Trichlorobenzene) -Flow rate: 1.0ml / min -Sample concentration: 1.0 mg / ml -Injection volume: 200μl - Column temperature: 160℃ -Detector:Agilent High Temperature RI detector -Standard: Polystyrene (corrected with a cubic function).

[0041] According to one embodiment of the present invention, the porous polymer substrate 110 may be manufactured by a method (wet method) in which a polyolefin resin is kneaded with a plasticizer (diluents) at a high temperature to form a single phase, the polyolefin resin and the plasticizer are separated during the cooling process, the plasticizer is extracted to form pores, and then stretching and heat-fixing treatment are performed.

[0042] According to one embodiment of the present invention, the average pore size and maximum pore size of the separation membrane 100 for electrochemical elements can be easily manufactured by a person skilled in the art to conform to the scope of the present invention by adjusting the mixing ratio of plasticizers, the stretching ratio, and the heat-fixing treatment temperature.

[0043] According to one embodiment of the present invention, the thickness of the porous polymer substrate 110 may be 1 μm or more and 50 μm or less. The thickness of the porous polymer substrate may be 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, or 8 μm or more. The thickness of the porous polymer substrate may be 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Specifically, the thickness of the porous polymer substrate may be 2 μm or more and 45 μm or less, 3 μm or more and 40 μm or less, 4 μm or more and 35 μm or less, 5 μm or more and 30 μm or less, 6 μm or more and 25 μm or less, 7 μm or more and 20 μm or less, or 8 μm or more and 15 μm or less. By adjusting the thickness of the porous polymer substrate within the above ranges, the energy density of the battery can be improved.

[0044] According to one embodiment of the present invention, the porosity of the porous polymer substrate 110 may be 10% by volume or more and 90% by volume or less. The porosity of the porous polymer substrate may be 10% by volume or more, 20% by volume or more, 30% by volume or more, or 40% by volume or more. The porosity of the porous polymer substrate may be 90% by volume or less, 80% by volume or less, 70% by volume or less, or 60% by volume or less. Specifically, the porosity of the porous polymer substrate may be 10% by volume or more and 90% by volume or less, 20% by volume or more and 80% by volume or less, 30% by volume or more and 70% by volume or less, or 40% by volume or more and 60% by volume or less. By adjusting the porosity of the porous polymer substrate within the above ranges, the permeability of the lithium ion separation membrane can be adjusted.

[0045] In this specification, porosity corresponds to the value obtained by subtracting (subtracting) the volume of each component of the porous polymer substrate 110 and / or coating layer 130 converted to weight and density from the volume calculated using the thickness, width, and length of the porous polymer substrate 110 and / or coating layer 130.

[0046] In this specification, the porosity and pore size of the porous polymer substrate 110 and / or coating layer 130 are determined by scanning electron microscope (SEM) images, a mercury porosimeter, a capillary flow porometer, or Porosimetry can be measured using the BET method via nitrogen gas adsorption flow using a porosimetry analyzer (Bell Japan Inc., Belsorp-II mini). Using a capillary flow porometer is advantageous in this case.

[0047] According to one embodiment of the present invention, the separation membrane 100 for an electrochemical element includes a coating layer 130 provided on at least one surface of a porous polymer substrate 110 (preferably directly provided). Specifically, the separation membrane 100 for an electrochemical element includes a coating layer 130 on one surface of the porous polymer substrate 110 (preferably directly provided) as shown in Figure 1, or includes a coating layer 130 provided on both sides of the porous polymer substrate 110 (preferably directly provided) as shown in Figure 2. As described above, by including a coating layer 130 provided on at least one surface of the porous polymer substrate 110 in the separation membrane 100, the heat resistance of the separation membrane is improved, the mechanical properties are improved, and the separation membrane can shrink at high temperatures to prevent electrical short circuits of the electrodes.

[0048] According to one embodiment of the present invention, the separation membrane 100 for an electrochemical element includes a coating layer 130 containing a first polymer binder 131 (not shown) and inorganic particles 133 (not shown). As described above, the inclusion of the first polymer binder 131 and inorganic particles 133 in the coating layer 130 improves the heat resistance of the separation membrane, improves its mechanical properties, allows the separation membrane to shrink at high temperatures to prevent electrical short circuits of the electrodes, and allows for the formation of pores inside the coating layer.

[0049] According to one embodiment of the present invention, the coating layer 130 may contain a plurality of pores. Specifically, the coating layer may be a porous coating layer. More specifically, the coating layer may be a porous coating layer containing a plurality of pores internally. As described above, by containing a plurality of pores in the coating layer, lithium ions can pass through and current can flow while physically separating the negative electrode and the positive electrode.

[0050] According to one embodiment of the present invention, the coating layer 130 can be formed by accumulating inorganic particles 133 bound together by a first polymer binder 131 within the coating layer. Pores inside the coating layer 130 may result from interstitial volume, which is the empty space between the inorganic particles 133.

[0051] According to one embodiment of the present invention, the first polymer binder 131 may be an acrylic binder, a polyvinylidene binder, or a combination thereof. Preferably, the first polymer binder 131 may be an acrylic binder. As described above, by selecting the first polymer binder 131 from the above, the heat resistance of the coating layer can be improved and the bonding strength of inorganic particles in the coating layer can be improved.

[0052] According to one embodiment of the present invention, the acrylic binder contained in the first polymer binder 131 is a polymer containing carboxylic acid esters as repeating units, and is preferably a (metho)acrylic acid ester or an acrylic-styrene copolymer.

[0053] According to one embodiment of the present invention, specific examples of the (metho)acrylate ester include methyl (metho)acrylate, ethyl (metho)acrylate, n-propyl (metho)acrylate, i-propyl (metho)acrylate, n-butyl (metho)acrylate, i-butyl (metho)acrylate, n-amyl (metho)acrylate, i-amyl (metho)acrylate, hexyl (metho)acrylate, cyclohexyl (metho)acrylate, 2-ethylhexyl (metho)acrylate, n-octyl (metho)acrylate, nonyl (metho)acrylate, (metho)acrylate Examples include decyl (t)acrylate, hydroxymethyl (metho)acrylate, hydroxyethyl (metho)acrylate, ethylene glycol (metho)acrylate, ethylene glycol di(metho)acrylate, propylene glycol di(metho)acrylate, trimethylolpropane tri(metho)acrylate, pentaerythritol tetra(metho)acrylate, dipentaerythritol hexa(metho)acrylate, aryl (metho)acrylate, and ethylene di(metho)acrylate, and one or more selected from these may be used. Of these, one or more selected from methyl (metho)acrylate, ethyl (metho)acrylate, and 2-ethylhexyl (metho)acrylate is preferred, and methyl (metho)acrylate is particularly preferred.

[0054] 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 acrylic binder may be one or more selected from the group consisting of styrene-butadiene rubber, nitril-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene rubber, and acrylate polymers, and more specifically, it may be a copolymer containing acrylate.

[0055] According to one embodiment of the present invention, the polyvinylidene binder contained in the first polymer binder 131 may be a polyvinylidene fluoride (PVdF) binder. As mentioned above, by selecting a polyvinylidene fluoride binder instead of a polyvinylidene binder, the resistance of the separation membrane can be reduced.

[0056] According to one embodiment of the present invention, the first polymer binder 131 may be in particle form or liquid form. By selecting the first polymer binder 131 from the above, the porosity and air permeability of the coating layer can be adjusted, the size of the pores in the coating layer can be adjusted, and the mechanical properties of the coating layer can be improved.

[0057] According to one embodiment of the present invention, the polyvinylidene (PVdF) binder contained in the first polymer binder 131 may have a hexafluoropropylene (HFP) content of 10% by weight or more. Specifically, the polyvinylidene binder contained in the first polymer binder 131 may have a hexafluoropropylene content of 10% to 80% by weight, 15% to 75% by weight, 20% to 70% by weight, 25% to 65% by weight, 30% to 60% by weight, 35% to 55% by weight, or 40% to 50% by weight. In the first polymer binder 131, the resistance of the separation membrane can be reduced by adjusting the hexafluoropropylene content contained in the polyvinylidene binder within the above ranges. In the polyvinylidene (PVdF) binder, the content of the hexafluoropropylene (HFP) monomer is 1 H-NMR and / or 19 It can be measured using F-NMR.

[0058] According to an embodiment of the present invention, the content of the first polymer binder 131 may be 10 parts by weight or less with respect to 100 parts by weight of the coating layer. The content of the first polymer binder 131 may exceed 0 parts by weight, be 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more with respect to 100 parts by weight of the coating layer. The content of the first polymer binder 131 may be 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, or 6 parts by weight or less with respect to 100 parts by weight of the coating layer. Specifically, the content of the first polymer binder 131 may exceed 0 parts by weight and be 10 parts by weight or less, be 1 part by weight or more and 9 parts by weight or less, be 2 parts by weight or more and 8 parts by weight or less, be 3 parts by weight or more and 7 parts by weight or less, or be 4 parts by weight or more and 6 parts by weight or less with respect to 100 parts by weight of the coating layer (130). By adjusting the content of the first polymer binder 131 within the above-mentioned range, the mechanical properties of the coating layer 130 can be improved, the porosity of the coating layer can be maintained, and the heat resistance can be improved. The content of the first polymer binder in the coating layer can be determined from the content of the first polymer binder in a composition such as a slurry for the coating layer.

[0059] According to an embodiment of the present invention, the average diameter (D 50 ) of the first polymer binder 131 is not particularly limited, but is preferably in the range of 0.1 μm or more and 1 μm or less for forming a coating layer 130 with a uniform thickness and an appropriate porosity. The average diameter (D 50 ) of the first polymer binder 131 may be 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more. The average diameter (D 50 ) of the first polymer binder 131 may be 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, or 0.6 μm or less. Specifically, the average diameter (D 50 ) of the first polymer binder 131 may be 0.2 μm or more and 0.9 μm or less, 0.3 μm or more and 0.8 μm or less, 0.4 μm or more and 0.7 μm or less, or 0.5 μm or more and 0.6 μm or less. The average diameter (D 50By adjusting the ), the dispersibility in the slurry prepared for the manufacture of the coating layer can be improved, and the thickness of the formed coating layer can be reduced. In this specification, "D 50 "Particle size" refers to the particle size at the 50% point of the cumulative particle number distribution by particle size. 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 analyzer (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam. By calculating the particle diameter at the point where the cumulative particle number distribution by particle size in the measuring device reaches 50%, the D50 particle size can be measured.

[0060] According to one embodiment of the present invention, the content of inorganic particles 133 in the coating layer 130 may be 90 parts by weight or more per 100 parts by weight of the coating layer (130). The content of inorganic particles 133 in the coating layer 130 may be 90 parts by weight or more, 91 parts by weight or more, 92 parts by weight or more, 93 parts by weight or more, or 94 parts by weight or more per 100 parts by weight of the coating layer (130). The content of inorganic particles 133 in the coating layer 130 may be less than 100 parts by weight, 99 parts by weight or less, 98 parts by weight or less, 97 parts by weight or less, or 96 parts by weight or less per 100 parts by weight of the coating layer (130). Specifically, the content of inorganic particles 133 in the coating layer 130 may be 90 parts by weight or more but less than 100 parts by weight, 91 parts by weight or more but 99 parts by weight or less, 92 parts by weight or more but 98 parts by weight or less, 93 parts by weight or more but 97 parts by weight or less, or 94 parts by weight or more but 96 parts by weight or less, per 100 parts by weight of the coating layer (130). By adjusting the content of inorganic particles 133 within the above ranges, the heat resistance and mechanical properties of the separation membrane can be improved. The content of inorganic particles in the coating layer can be determined from the content of inorganic particles in a composition such as a slurry for the coating layer.

[0061] According to one embodiment of the present invention, the inorganic particles 133 that can be used in the coating layer 130 are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are within the operating voltage range of the electrochemical element to which they are applied (e.g., Li / Li + There are no particular limitations as long as oxidation and / or reduction reactions do not occur at a reference voltage of 0V to 5V.

[0062] According to one embodiment of the present invention, when inorganic particles with a high dielectric constant are used, the inorganic particles contribute to increasing the dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte solution. For the reasons mentioned above, the inorganic particles may be inorganic particles with a dielectric constant of 5 or more, inorganic particles having lithium ion transport capability, or a mixture thereof.

[0063] According to one embodiment of the present invention, non-limiting examples of inorganic particles 133 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), and may contain one or more of these.

[0064] According to one embodiment of the present invention, the average diameter (D) of the inorganic particles 133 is 50 There are no special restrictions on the average diameter (D) of the inorganic particles 133, but it is preferable that it be in the range of 0.3 μm to 1 μm in order to form a coating layer of uniform thickness and appropriate porosity. For example, the average diameter (D) of the inorganic particles 13350 The particle size may be 0.5 μm or more, 0.7 μm or less, or 0.6 μm. Specifically, if it is less than 0.3 μm, the dispersibility of inorganic particles in the slurry prepared for coating layer production may decrease, and if it exceeds 1 μm, the thickness of the formed coating layer may increase.

[0065] In this specification, "D 50 "Particle size" refers to the particle size at the 50% point of the cumulative particle number distribution by particle size. 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 analyzer (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam. By calculating the particle diameter at the point where the cumulative particle number distribution by particle size in the measuring device reaches 50%, the D50 particle size can be measured.

[0066] According to one embodiment of the present invention, the separation membrane 100 for the electrochemical element includes an adhesive layer 150 provided on (preferably directly installed on) the coating layer 130. As described above, by including the adhesive layer 150 provided on the coating layer 130 in the separation membrane 100 for the electrochemical element, the adhesive strength between the electrode and the separation membrane during the lamination process of the separation membrane with the electrode can be ensured.

[0067] According to one embodiment of the present invention, the adhesive layer 150 includes a second polymer binder 151 containing a polyvinyl acetate resin. More specifically, the adhesive layer 150 may be polyvinyl acetate. As described above, by including a second polymer binder 151 containing a polyvinyl acetate resin in the adhesive layer 150, dry adhesion to the electrode can be ensured.

[0068] According to one embodiment of the present invention, the content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 is 0 g / m². 2 Super 1.5g / m 2The following applies: The content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 is 0.1 g / m². 2 More than 0.2g / m 2 More than 0.3g / m 2 More than 0.5g / m 2 More than 0.8g / m 2 More than 0.9g / m 2 The amount may be greater than or equal to the amount of the second polymer binder 151 per unit area of ​​the adhesive layer 150 is 1.4 g / m². 2 Below 1.3g / m 2 Below 1.2g / m 2 Below, 1.1g / m 2 Below 1.0g / m 2 The following may also apply. Specifically, the content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 is 0.1 g / m². 2 More than 1.5g / m 2 Below, 0.2g / m 2 More than 1.4g / m 2 Below 0.5g / m 2 More than 1.3g / m 2 Below, 0.8g / m 2 More than 1.2g / m 2 Below, 0.9g / m 2 More than 1.1g / m 2 The following may also apply. For example, the content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 may be 0.2 g / m². 2 More than 1.0g / m 2 The following is also possible. By adjusting the content of the second polymer binder 151 per unit area of ​​the adhesive layer 150 within the range described above, the amount of the second polymer binder 151 dissolved by the electrolyte can be reduced, thereby reducing the viscosity of the electrolyte, which in turn can reduce the resistance of the separation membrane and improve the adhesive strength. In the adhesive layer, the content of the second polymer binder can be determined from the content of the second polymer binder in a composition such as an adhesive layer slurry.

[0069] According to one embodiment of the present invention, the second polymer binder 151 may be in particle form. That is, it may consist of various second polymer binder 151 particles. As mentioned above, by selecting the second polymer binder 151 in particle form, the porosity of the separation membrane can be improved.

[0070] According to one embodiment of the present invention, there are no special restrictions on the average diameter (D50) of the second polymer binder 151 particles, but it is preferable that it be in the range of 0.1 μm to 1 μm in order to form an adhesive layer 150 of uniform thickness and an appropriate porosity. 50 The particle size may be 0.2 μm or larger, 0.3 μm or larger, 0.4 μm or larger, or 0.5 μm or larger. The average diameter (D) of the second polymer binder 151 particles. 50 The average diameter (D) of the second polymer binder 151 may be 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, or 0.6 μm or less. Specifically, the average diameter (D) of the second polymer binder 151 50 The average diameter (D) of the second polymer binder 151 within the above range may be 0.2 μm to 0.9 μm, 0.3 μm to 0.8 μm, 0.4 μm to 0.7 μm, or 0.5 μm to 0.6 μm. 50 By adjusting the particle size, dispersibility can be improved in the slurry prepared for adhesive layer production, and the thickness of the formed adhesive layer can be reduced. In this specification, "D50 particle size" refers to the particle size at the 50% point of the cumulative particle number distribution by 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 analyzer (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam. The D50 particle size can be measured by calculating the particle diameter at the point where the cumulative particle number distribution by particle size in the measuring device reaches 50%.

[0071] Figure 3 is a schematic diagram of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. Figure 4 is a schematic diagram of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. Specifically, Figure 3 is a schematic diagram of a separation membrane 100 for an electrochemical element in which a coating layer 130 and an adhesive layer 150 are provided on one surface, and the adhesive layer 150 includes a third polymer binder 153. Figure 4 is a schematic diagram of a separation membrane 100 for an electrochemical element in which a coating layer 130 and an adhesive layer 150 are provided on both sides, and the adhesive layer 150 includes a third polymer binder. The separation membrane 100 for an electrochemical element according to one embodiment of the present invention will be specifically described with reference to Figures 3 and 4.

[0072] According to one embodiment of the present invention, the adhesive layer 150 may further contain a third polymer binder 153 containing a polyvinylidene-based binder. As described above, by further including the third polymer binder 153 containing a polyvinylidene-based binder, the increase in resistance due to the electrolyte can be minimized and the wet adhesive strength can be improved.

[0073] According to one embodiment of the present invention, the polyvinylidene binder may have a hexafluoropropylene (HFP) content of 40% by weight or less. The polyvinylidene binder may have a hexafluoropropylene (HFP) content of more than 0% by weight, 5% or more by weight, 10% or more by weight, or 15% or more by weight. The polyvinylidene binder may have a hexafluoropropylene (HFP) content of 40% or less by weight, 35% or less by weight, 30% or less by weight, or 25% or less by weight.

[0074] Specifically, the polyvinylidene binder may contain hexafluoropropylene in amounts greater than 0% by weight and 40% by weight or less, 5% by weight or more and 35% by weight or less, 10% by weight or more and 30% by weight or less, or 15% by weight or more and 25% by weight or less. By adjusting the hexafluoropropylene content in the polyvinylidene binder within the aforementioned ranges, the porosity of the separation membrane can be maintained and the resistance of the separation membrane can be improved.

[0075] According to one embodiment of the present invention, the polyvinylidene binder may be a polyvinylidene fluoride (PVdF) binder. As mentioned above, by selecting a polyvinylidene fluoride binder such as polyvinylidene difluoride, the porosity of the separation membrane can be maintained and the resistance of the separation membrane can be improved.

[0076] According to one embodiment of the present invention, the polyvinylidene binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As mentioned above, by selecting a copolymer of polyvinylidene fluoride and hexafluoropropylene as the polyvinylidene binder, the dissolution of the third polymer binder by the electrolyte can be minimized, and the wet adhesion strength can be improved.

[0077] According to one embodiment of the present invention, the adhesive layer 150 may include a second polymer binder and a third polymer binder.

[0078] In an embodiment of the present invention, the weight ratio of the second polymer binder 151 to the third polymer binder 153 in the adhesive layer 150 may be 99:1 to 50:50. Specifically, the weight ratio of the second polymer binder 151 to the third polymer binder 153 in the adhesive layer 150 may be 95:5 to 55:45, 90:10 to 60:40, 85:15 to 65:35, or 80:20 to 70:30. Preferably, it may be 70:30. By adjusting the weight ratio of the second polymer binder 151 to the third polymer binder 153 in the adhesive layer 150 within the above range, it is possible to prevent the resistance of the separation membrane from increasing due to the electrolyte, while simultaneously improving the dry adhesion strength.

[0079] In this specification, dry adhesive strength refers to the value obtained when a separation membrane is cut to 70 mm (length) x 25 mm (width), a test specimen is prepared by laminating the prepared negative electrode and separation membrane using a press at 60°C, 6.5 MPa, and 1 sec, the prepared test specimen is then attached and fixed to a glass plate using double-sided tape, with the negative electrode facing the glass plate, and the separation membrane portion of the test specimen is peeled off at a 180° angle at a speed of 150 mm / min at 25°C, and the strength at this time is measured.

[0080] In this specification, wet adhesion strength refers to the value obtained when a test specimen is prepared by cutting the separation membrane to 70 mm (length) x 25 mm (width), laminating the prepared negative electrode and separation membrane using a press at 60°C, 6.5 MPa, and 1 sec, then placing the prepared test specimen in a battery case with the electrolyte, maintaining it for 4 hours to impregnate the test specimen in the electrolyte (a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 7:3, with LiPF6 at a concentration of 1 M), then removing the test specimen from the case, attaching and fixing it to a glass plate using double-sided tape, with the negative electrode facing the glass plate, and then peeling off the separation membrane portion of the test specimen at a 90° angle at a speed of 200 mm / min at 25°C, and measuring the strength at that time.

[0081] According to one embodiment of the present invention, the content of the second polymer binder 151 and the third polymer binder 153 per unit area of ​​the adhesive layer 150 is 0 g / m². 2 Super 1.5g / m 2 The following may also apply: The content of the second polymer binder 151 and the third polymer binder 153 per unit area of ​​the adhesive layer 150 is 0.1 g / m². 2 Below, 0.2g / m 2 Below, 0.3g / m 2 Below 0.5g / m 2 Below, 0.8g / m 2 Below, 0.9g / m 2 The following may also apply: The content of the second polymer binder 151 and the third polymer binder 153 per unit area of ​​the adhesive layer 150 is 1.4 g / m². 2 Below 1.3g / m2 Below 1.2g / m 2 Below, 1.1g / m 2 Below 1.0g / m 2 The following may also apply: Specifically, the total content of the second polymer binder 151 and the third polymer binder 153 per unit area of ​​the adhesive layer 150 is 0.1 g / m². 2 More than 1.5g / m 2 Below, 0.3g / m 2 More than 1.4g / m 2 Below 0.5g / m 2 More than 1.3g / m 2 Below, 0.7g / m 2 More than 1.2g / m 2 The following or 0.9g / m 2 More than 1.1g / m 2 The following may also apply. By adjusting the total content of the second polymer binder and the third polymer binder per unit area of ​​the adhesive layer within the aforementioned range, the amount of the second polymer binder dissolved by the electrolyte can be reduced, thereby decreasing the viscosity of the electrolyte, which in turn can reduce the resistance of the separation membrane and improve the adhesive strength. The content of the second polymer binder and the third polymer binder in the adhesive layer can be determined from the content of the second polymer binder and the third polymer binder in a composition such as an adhesive layer slurry.

[0082] According to one embodiment of the present invention, the thickness of the coating layer 130 on either of the porous polymer substrates 110 may be greater than 0 μm and less than or equal to 2.0 μm. The thickness of the coating layer 130 on either of the porous polymer substrates 110 may be 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, 1.0 μm or more, 1.1 μm or more, 1.2 μm or more, 1.3 μm or more, or 1.4 μm or more. The thickness of the coating layer 130 on either of the porous polymer substrates 110 may be 2.0 μm or less, 1.9 μm or less, 1.8 μm or less, 1.7 μm or less, or 1.6 μm or less. Specifically, the thickness of the coating layer 130 may be greater than 0 μm and less than or equal to 2.0 μm, 0.1 μm to 1.9 μm, 0.2 μm to 1.8 μm, 0.3 μm to 1.7 μm, 0.4 μm to 1.6 μm, 0.5 μm to 1.5 μm, 0.6 μm to 1.4 μm, 0.7 μm to 1.3 μm, 0.8 μm to 1.2 μm, or 0.9 μm to 1.1 μm. Preferably, it may be 1.5 μm. By adjusting the thickness of the coating layer 130 within the above range, the heat resistance of the separation membrane can be improved and the energy density of the separation membrane can be increased.

[0083] According to one embodiment of the present invention, the thickness of the adhesive layer 150 may be greater than 0 μm and less than or equal to 1.0 μm. The thickness of the adhesive layer 150 may be 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, or 0.4 μm or more. The thickness of the adhesive layer 150 may be 1.0 μm or less, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, or 0.6 μm or less. Specifically, the thickness of the coating layer 130 may be greater than 0 μm and less than or equal to 1.0 μm, 0.1 μm or more and less

[0084] In one embodiment of the present invention, the thickness of the polymer substrate and / or the coating layer and / or adhesive layer can be measured using a contact-type thickness gauge. For example, the VL-50S-B from Mitutoyo can be used as the contact-type thickness gauge.

[0085] According to one embodiment of the present invention, the separation film 100 for the electrochemical element may have a resistance of 0.85 Ω or less. The separation film 100 for the electrochemical element may have a resistance greater than 0 Ω, 0.10 Ω or more, 0.15 Ω or more, 0.20 Ω or more, 0.25 Ω or more, 0.30 Ω or more, 0.35 Ω or more, 0.40 Ω or more, or 0.50 Ω or more. The separation film 100 for the electrochemical element may have a resistance of 0.85 Ω or less, 0.80 Ω or less, 0.75 Ω or less, 0.70 Ω or less, 0.65 Ω or less, 0.60 Ω or less, 0.55 Ω or less, or 0.50 Ω or less. Specifically, the isolation film for the electrochemical element may have a resistance of greater than 0Ω and less than or equal to 0.90Ω, 0.05Ω to less than or equal to 0.85Ω, 0.10Ω to less than or equal to 0.80Ω, 0.15Ω to less than or equal to 0.75Ω, 0.20Ω to less than or equal to 0.70Ω, 0.25Ω to less than or equal to 0.65Ω, 0.30Ω to less than or equal to 0.60Ω, 0.35Ω to less than or equal to 0.55Ω, or 0.40Ω to less than or equal to 0.50Ω. By adjusting the resistance of the isolation film for the electrochemical element within the aforementioned ranges, battery performance can be improved.

[0086] In this specification, "resistance" may refer to the value obtained when a coin cell is fabricated by interposing a separation membrane between SUS materials and injecting an electrolyte solution prepared by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 3:7 ratio with LiPF6 at a concentration of 1 M, and then measuring the resistance (ER) by the EIS method. In this case, the frequency may be in the range of 100,000 to 10,000 Hz.

[0087] According to one embodiment of the present invention, the second polymer binder may be particle-type, dissolvable, or a combination thereof. In this specification, "particle-type" means that the second polymer binder maintains its particle shape because it is not dissolved by the electrolyte injected into the battery. In this specification, "dissolvable" means that the second polymer binder cannot maintain its particle shape because it is dissolved by the electrolyte injected into the battery. By selecting the second polymer binder from the above, the dry adhesion and wet adhesion to the electrode can be improved.

[0088] According to one embodiment of the present invention, an adhesive layer may be provided on a portion of the coating layer 130. Specifically, a second polymer binder may be provided on a portion of the coating layer 130. As described above, by providing an adhesive layer on a portion of the coating layer 130, the dry adhesion strength and wet adhesion strength with the electrode can be improved.

[0089] According to one embodiment of the present invention, the adhesive layer may be provided in an area greater than 0% but less than 100% of the total area of ​​the coating layer. Specifically, the second polymer binder may be provided in an area greater than 0% but less than 100% of the total area of ​​the coating layer. Specifically, the area on which the second polymer binder is provided on the coating layer may be 1% to 99%, 5% to 95%, 10% to 90%, 15% to 85%, 20% to 80%, 25% to 75%, 30% to 70%, 35% to 65%, 40% to 60%, or 45% to 55% of the total area of ​​the coating layer. By adjusting the area on which the second polymer binder is provided on the coating layer within the above ranges, the dry adhesion strength and wet adhesion strength with the electrode can be improved.

[0090] According to one embodiment of the present invention, the second polymer binder is provided on a portion of the coating layer by a spray method, bar coating, spin coating, or deep coating method. By selecting a method for providing the adhesive polymer binder from the above, the adhesive polymer binder can be easily placed on the coating layer. One embodiment of the present invention provides a method for manufacturing a separation membrane for an electrochemical element, comprising the steps of: applying a coating layer slurry containing a first polymer binder 131 and inorganic particles 135 onto at least one surface of a porous polymer substrate 110 for the formation of a coating layer; and applying an adhesive layer slurry containing a second polymer binder for the formation of an adhesive layer.

[0091] A method for manufacturing an electrochemical element according to one embodiment of the present invention can easily prevent an increase in the resistance of the separation membrane, and the energy density of the battery can be improved by manufacturing the separation membrane as a thin film. In the method for manufacturing a separation membrane for an electrochemical element according to one embodiment of the present invention, content that overlaps with the description of the separation membrane for an electrochemical element is omitted.

[0092] According to one embodiment of the present invention, a method for manufacturing an electrochemical element includes the step of applying a coating layer slurry containing a first polymer binder 131 and inorganic particles 135 onto at least one surface of a porous polymer substrate 110. As described above, by including the step of applying a coating layer slurry onto at least one surface of the porous polymer substrate, a coating layer can be formed in a single application, the heat resistance of the separation membrane is improved by the inorganic particles present in an appropriate amount in the coating layer slurry, and the solvent can be easily evaporated. That is, this refers to the solvent contained in the coating layer slurry other than the first polymer binder 131 and inorganic particles 135. The coating layer slurry may contain the first polymer binder 131, inorganic particles 135, and a solvent.

[0093] According to one embodiment of the present invention, prior to the step of applying the slurry for the coating layer, a first polymer binder is dispersed in a suitable dispersion medium to produce a polymer emulsion and obtain a slurry. The solvent is preferably one that has a similar solubility index to the binder polymer used and a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of usable solvents include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. In this specification, the dispersion medium may mean the solvent used in the process of producing the slurry.

[0094] According to one embodiment of the present invention, inorganic particles can be added to and dispersed in a polymer emulsion. The content ratio of inorganic particles to polymer binder particles is as described above and can be appropriately adjusted considering the thickness, pore size, and porosity of the coating layer produced by the final embodiment of the present invention.

[0095] According to one embodiment of the present invention, the slurry for the coating layer may be obtained by adding a first polymer binder and inorganic particles to water, which is a dispersion medium, and dispersing them.

[0096] According to one embodiment of the present invention, the slurry for the coating layer may further contain a dispersant. The slurry for the coating layer may contain a first polymer binder 131, inorganic particles 135, a solvent, and a dispersant. Specifically, the slurry for the coating layer may contain sodium carboxymethylcellulose (SG-L02, GLCHEM) as a dispersant. As described above, the dispersibility of the slurry for the coating layer can be improved by further containing a dispersant.

[0097] According to one embodiment of the present invention, in a slurry for a coating layer, the content of the dispersant may be 0.5 parts by weight or more and 2 parts by weight or less per 100 parts by weight of the total content of the first polymer binder, inorganic particles and dispersant. By adjusting the content of the dispersant within the above range, the dispersibility of the slurry for a coating layer can be improved.

[0098] According to one embodiment of the present invention, the inorganic particle content in the coating layer slurry may be 90 parts by weight or more per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. The inorganic particle content in the coating layer slurry may be 90 parts by weight or more, 91 parts by weight or more, 92 parts by weight or more, 93 parts by weight or more, or 94 parts by weight or more per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. The inorganic particle content in the coating layer slurry may be less than 100 parts by weight, 99 parts by weight or less, 98 parts by weight or less, 97 parts by weight or less, or 96 parts by weight or less per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. Specifically, the inorganic particle content in the coating layer slurry may be 90 parts by weight or more but less than 100 parts by weight, 91 parts by weight or more but 99 parts by weight or less, 92 parts by weight or more but 98 parts by weight or less, 93 parts by weight or more but 97 parts by weight or less, or 94 parts by weight or more but 96 parts by weight or less, per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. By adjusting the content of inorganic particles 133 within the above ranges, the heat resistance and mechanical properties of the separation membrane can be improved.

[0099] According to one embodiment of the present invention, the content of the first polymer binder in the coating layer slurry may be 10 parts by weight or less per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. The content of the first polymer binder in the coating layer slurry may be more than 0 parts by weight, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. The content of the first polymer binder in the coating layer slurry may be 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, or 6 parts by weight or less per 100 parts by weight of the total content of the first polymer binder, inorganic particles, and dispersant. Specifically, the content of the first polymer binder in the coating layer slurry may be more than 0 parts by weight and 10 parts by weight or less, 1 part by weight or more and 9 parts by weight or less, 2 parts by weight or more and 8 parts by weight or less, 3 parts by weight or more and 7 parts by weight or less, or 4 parts by weight or more and 6 parts by weight or less, based on 100 parts by weight of the total content of the first polymer binder, inorganic particles and dispersant. By adjusting the content of the first polymer binder 131 within the above ranges, the mechanical properties of the coating layer 130 can be improved, the porosity of the coating layer can be maintained, and the heat resistance can be improved.

[0100] According to one embodiment of the present invention, the method for applying the coating layer slurry to the surface of the porous polymer substrate 110 is not limited to any one of the methods, and conventional methods known in the art can be used. For example, a variety of methods can be used, such as deep coating, die coating, roll coating, comma coating, or a mixture thereof.

[0101] According to one embodiment of the present invention, a method for manufacturing an electrochemical element includes the step of applying an adhesive layer slurry containing a second polymer binder 151. As described above, by including the step of applying an adhesive layer slurry containing a second polymer binder 151, an adhesive layer can be easily formed, and the loading amount of the second polymer binder (the total weight of the second polymer binder and / or third polymer binder contained in the adhesive layer) can be easily adjusted.

[0102] According to one embodiment of the present invention, the method for applying the adhesive layer slurry to the surface of the porous polymer substrate 110 is not limited to any one of the methods, and conventional methods known in the art can be used. For example, a variety of methods can be used, such as deep coating, die coating, roll coating, comma coating, or a mixture thereof.

[0103] According to one embodiment of the present invention, the slurry for the adhesive layer may further contain a solvent, and the solvent may be water. As described above, by further containing a solvent in the slurry for the adhesive layer, the second polymer binder and the third polymer binder can be uniformly dispersed.

[0104] According to one embodiment of the present invention, the slurry for the adhesive layer may contain a second polymer binder and a solvent. According to one embodiment of the present invention, the slurry for the adhesive layer may contain a second polymer binder, a third polymer binder and a solvent.

[0105] According to one embodiment of the present invention, the content of the second polymer binder in the adhesive layer slurry may be 1 part by weight or more and 99 parts by weight or less per 100 parts by weight of the adhesive layer slurry. The content of the second polymer binder in the adhesive layer slurry may be 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, or 40 parts by weight or more per 100 parts by weight of the adhesive layer slurry. The content of the second polymer binder in the adhesive layer slurry may be 90 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, or 60 parts by weight or less per 100 parts by weight of the adhesive layer slurry. Specifically, the content of the second polymer binder in the adhesive layer slurry may be 10 parts by weight or more and 90 parts by weight or less, 20 parts by weight or more and 80 parts by weight or less, 30 parts by weight or more and 70 parts by weight or less, or 40 parts by weight or more and 60 parts by weight or less per 100 parts by weight of the adhesive layer slurry. By adjusting the content of the second polymer binder within the aforementioned range, the viscosity of the electrolyte can be reduced, thereby reducing the resistance of the separation membrane and improving adhesion.

[0106] According to one embodiment of the present invention, the solid content of the slurry for the adhesive layer may be 10% by weight or more and 30% by weight or less. The solid content of the slurry for the adhesive layer may be 11% by weight or more, 12% by weight or more, 13% by weight or more, 14% by weight or more, 15% by weight or more, 16% by weight or more, 17% by weight or more, 18% by weight or more, or 19% by weight or more. The solid content of the slurry for the adhesive layer may be 29% by weight or less, 28% by weight or less, 27% by weight or less, 26% by weight or less, 25% by weight or less, 24% by weight or less, 23% by weight or less, 22% by weight or less, or 21% by weight or less. Specifically, the solid content of the slurry for the adhesive layer may be 11% to 29% by weight, 12% to 28% by weight, 13% to 27% by weight, 14% to 26% by weight, 15% to 25% by weight, 16% to 24% by weight, 17% to 23% by weight, 18% to 22% by weight, or 19% to 21% by weight. By adjusting the solid content of the slurry for the adhesive layer within the aforementioned ranges, the second polymer binder and the third polymer binder to be placed on the coating layer can be easily applied, and the amount to be placed can be easily adjusted.

[0107] According to one embodiment of the present invention, a method for manufacturing an electrochemical element may include the step of drying a slurry for a coating layer to provide a coating layer. As described above, by including the step of drying a slurry for a coating layer to provide a coating layer, damage to the coating layer can be minimized and the solvent contained in the slurry can be easily removed.

[0108] According to one embodiment of the present invention, the temperature of the drying process for the coating layer may be 25°C to 75°C. Specifically, the temperature of the drying process for the coating layer may be 30°C to 70°C, 35°C to 65°C, 40°C to 60°C, or 45°C to 55°C. By adjusting the temperature of the drying process for the coating layer within the above ranges, modification of the porous polymer substrate can be prevented and the dispersion medium can be effectively removed.

[0109] According to one embodiment of the present invention, a method for manufacturing an electrochemical element may include the step of drying an adhesive layer slurry to provide an adhesive layer. As described above, by including the step of drying an adhesive layer slurry to provide an adhesive layer, damage to the adhesive layer can be minimized and the solvent contained in the slurry can be easily removed.

[0110] According to one embodiment of the present invention, the temperature of the drying process for the adhesive layer may be 25°C or more and 75°C or less. Specifically, the temperature of the drying process for the adhesive layer may be 30°C or more and 70°C or less, 35°C or more and 65°C or less, 40°C or more and 60°C or less, or 45°C or more and 55°C or less. By adjusting the temperature of the drying process for the adhesive layer within the above ranges, modification of the porous polymer substrate can be prevented and the solvent can be effectively removed.

[0111] According to one embodiment of the present invention, the method for manufacturing an electrochemical element may include the step of applying a slurry for the adhesive layer, and then drying the slurry for the coating layer and the slurry for the adhesive layer at the same time to provide a coating layer and an adhesive layer. As described above, by including the step of applying a slurry for the adhesive layer and then drying the slurry for the coating layer and the slurry for the adhesive layer at the same time to provide a coating layer and an adhesive layer in the method for manufacturing an electrochemical element, the coating layer and the adhesive layer can be easily formed.

[0112] According to one embodiment of the present invention, the drying process is configured to appropriately set time conditions so as to minimize the occurrence of surface defects in the coating layer. Drying aids such as drying ovens or hot air may be used in the drying process within an appropriate range.

[0113] According to one embodiment of the present invention, the separation membrane is interposed between the negative electrode and the positive electrode 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 may 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 stacked 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.

[0114] One embodiment of the present invention provides an electrochemical element 1000 comprising a positive electrode 300; a negative electrode 500; a separation membrane 100; and an electrolyte, wherein the separation membrane 100 is the aforementioned separation membrane for electrochemical elements interposed between the positive electrode 300 and the negative electrode 500.

[0115] An electrochemical element according to one embodiment of the present invention can lower the viscosity of the electrolyte by adjusting the solubility of the polymer binder contained in the adhesive layer in the electrolyte, thereby improving the ionic conductivity of the battery while simultaneously lowering the surface resistance of the battery.

[0116] Figure 5 is a schematic diagram of an electrochemical element 1000 according to one embodiment of the present invention. The electrochemical element 1000 according to one embodiment of the present invention will be described in detail with reference to Figure 5.

[0117] In one embodiment of the present invention, an electrochemical element is a device that converts chemical energy into electrical energy through an electrochemical reaction, and is a concept that encompasses both primary batteries and secondary batteries. In this specification, a secondary battery is capable of charging and discharging, and means lithium secondary batteries, nickel-cadmium batteries, nickel-metal hydride batteries, etc. In the lithium secondary battery, lithium ions are used as the ion conductor, and examples include, but are 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.

[0118] According to one embodiment of the present invention, the positive electrode has a positive electrode current collector and a positive electrode active material layer on at least one side surface of the positive electrode 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 substituted with an alkaline earth metal ion; disulfide compounds; and may contain one or more of the following mixtures: Fe2(MoO4)3.

[0119] According to one embodiment of the present invention, the negative electrode has a negative electrode current collector and a negative electrode active material layer on at least one side surface of the negative electrode current collector, comprising a negative electrode active material, a conductive material, and a binder resin. The negative electrode is made of carbon such as lithium metal oxide, non-graphitizable carbon, and graphite-based carbon as the negative electrode active material; LixFe2O3 (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; one or more mixtures selected from titanium oxides may be included.

[0120] According to an 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 conductive materials selected from the group consisting of natural graphite, artificial graphite, super P (super-p), acetylene black, ketjen black, channel black, furnace black, lamp black, summer black, denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide.

[0121] According to an embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without inducing chemical changes in the battery. For example, stainless steel, copper, aluminum, nickel, titanium, plastic carbon, or those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel may be used.

[0122] According to one embodiment of the present invention, a polymer commonly used in electrodes in the industry may be used as the binder resin. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include, but are not limited to, acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methylcellulose.

[0123] In the present invention, the positive electrode slurry for manufacturing the positive electrode active material layer may contain a dispersant, and the dispersant may be a pyrrolidone-based compound. Specifically, it may be N-methylpyrrolidone (N-methylpyrrolidone, ADC-01, LG Chem).

[0124] According to an embodiment of the present invention, the content of the dispersant contained in the positive electrode slurry may be more than 0 parts by weight and 0.5 parts by weight or less with respect to 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant contained in the positive electrode slurry may be more than 0.05 parts by weight and 0.4 parts by weight or less with respect to 100 parts by weight of the positive electrode slurry.

[0125] According to an embodiment of the present invention, the negative electrode slurry for manufacturing the negative electrode active material layer contains a dispersant, and the dispersant may be a polypyrrolidone-based compound. Specifically, the dispersant may be polyvinylpyrrolidone (Polyvinylpyrrolidone, Junsei, Japan).

[0126] According to an 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 with respect to 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 with respect to 100 parts by weight of the negative electrode slurry.

[0127] According to an embodiment of the present invention, the electrochemical device prepared as described above can be manufactured into a battery by being housed in a suitable case and injecting an electrolyte.

[0128] According to an embodiment of the present invention, the electrolyte is a salt having a structure such as A + B - where A + is an ion composed of an alkali metal cation such as Li + Na + K + or a combination thereof, and B - is PF6 - BF4 - Cl - Br- , I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, and tetrahydrofuran are examples of salts containing anions such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, and tetrahydrofuran. These may be dissolved or dissociated in organic solvents consisting of N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone (γ-butyrolactone), or mixtures thereof, but are not limited to these.

[0129] According to one embodiment of the present invention, the solubility of the second polymer binder in the electrolyte may be 50(w / w)% or more and 80(w / w) or less at room temperature (25°C). The solubility of the second polymer binder in the electrolyte refers to the amount of second polymer binder dissolved in 100g of electrolyte (solute = second polymer binder, solvent = electrolyte) at room temperature. The solubility of the second polymer binder in the electrolyte is 51(w / w)% or more, 52(w / w)% or more, 53(w / w)% or more, 54(w / w)% or more, 55(w / w)% or more, 56(w / w)% or more, 57(w / w)% or more, 58(w / w)% or more, and 59(w / w)% at room temperature (25°C). The solubility of the second polymer binder in the electrolyte may be 79% or less, 78% or less, 77% or less, 76% or less, 75% or less, 74% or less, 73% or less, 72% or less, 71% or less, 70% or less, 69% or less, 68% or less, 67% or less, or 66% or less at room temperature (25°C). Specifically, the solubility of the second polymer binder in the electrolyte at room temperature is 51(w / w)% to 79(w / w)%, 52(w / w)% to 78(w / w)%, 53(w / w)% to 77(w / w)%, 54(w / w)% to 76(w / w)%, 55(w / w)% to 75(w / w)%, 56(w / w)% to 74(w / w)%, and 57(w / w)% or less. The solubility of the second polymer binder in the electrolyte can be 73(w / w)% or less, 58(w / w)% to 72(w / w)%, 59(w / w)% to 71(w / w)%, 60(w / w)% to 70(w / w)%, 61(w / w)% to 69(w / w)%, 62(w / w)% to 68(w / w)%, 63(w / w)% to 67(w / w)%, or 64(w / w)% to 66(w / w)%. By adjusting the solubility of the second polymer binder in the electrolyte within the aforementioned range, it is possible to prevent the second polymer from dissolving in the electrolyte and increasing the viscosity of the electrolyte, thereby improving the resistance and ionic conductivity of the separation membrane.

[0130] According to one embodiment of the present invention, the solubility of the third polymer binder in the electrolyte may be 50(w / w)% or more and 80(w / w) or less at room temperature (25°C). The solubility of the third polymer binder in the electrolyte refers to the amount of third polymer binder dissolved in 100g of electrolyte (solute = third polymer binder, solvent = electrolyte) at room temperature. The solubility of the third polymer binder in the electrolyte is 51(w / w)% or more, 52(w / w)% or more, 53(w / w)% or more, 54(w / w)% or more, 55(w / w)% or more, 56(w / w)% or more, 57(w / w)% or more, 58(w / w)% or more, and 59(w / w)% at room temperature (25°C). The solubility of the third polymer binder in the electrolyte may be 79% or less, 78% or less, 77% or less, 76% or less, 75% or less, 74% or less, 73% or less, 72% or less, 71% or less, 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, or 66% or less at room temperature (25°C). Specifically, the solubility of the third polymer binder in the electrolyte at room temperature is 51(w / w)% to 79(w / w)%, 52(w / w)% to 78(w / w)%, 53(w / w)% to 77(w / w)%, 54(w / w)% to 76(w / w)%, 55(w / w)% to 75(w / w)%, 56(w / w)% to 74(w / w)%, and 57(w / w)% or less. The solubility of the third polymer binder in the electrolyte can be 73(w / w)% or less, 58(w / w)% to 72(w / w)%, 59(w / w)% to 71(w / w)%, 60(w / w)% to 70(w / w)%, 61(w / w)% to 69(w / w)%, 62(w / w)% to 68(w / w)%, 63(w / w)% to 67(w / w)%, or 64(w / w)% to 66(w / w)%. By adjusting the solubility of the third polymer binder in the electrolyte within the above range, it is possible to prevent the third polymer from dissolving in the electrolyte and increasing the viscosity of the electrolyte, thereby improving the resistance and ionic conductivity of the separation membrane.

[0131] One embodiment of the present invention provides a battery module including a battery containing an 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 powered by a battery motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; electric motorcycles including electric bicycles (E-bikes), electric scooters, etc.; electric golf carts; and power storage systems. [Examples]

[0132] 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.

[0133] <Example 1>

[0134] A porous polymer substrate (total thickness approximately 9 μm, porosity 40% by volume) was manufactured by extruding polyethylene resin (weight-average molecular weight 900,000) using a wet process.

[0135] As inorganic particles, D is 600 nm in size. 50 Al2O3 powder with specific particle sizes was prepared. An acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) was prepared as the first binder polymer, and sodium carboxymethylcellulose (CMC-Na) (SG-L02, GLCHEM Co., Ltd.) was prepared as the dispersant.

[0136] The inorganic particles, first binder polymer, and dispersant prepared above were added to water, which is the dispersion medium, in a weight ratio of 97:2:1. After that, the inorganic particles were crushed and dispersed to produce a slurry for the coating layer.

[0137] A coating slurry was applied to both sides of a porous polymer substrate, and the mixture was dried to form a coating layer.

[0138] A slurry for the adhesive layer was prepared by adding polyvinyl acetate, used as the second polymer binder, to water, the solvent, and dispersing it so that the solid content was 20% by weight.

[0139] The adhesive slurry is applied to the coating layer, with a loading amount of polyvinyl acetate (average particle size (D50): 500 nm) of 1.0 g / m². 2 After applying the coating using a bar coating method, it was dried to form an adhesive layer, and a separation film for electrochemical elements was manufactured.

[0140] <Example 2>

[0141] In Example 1, the loading amount of polyvinyl acetate was 0.5 g / m². 2 A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that it was coated with a bar coating and then dried to form an adhesive layer.

[0142] <Example 3>

[0143] In Example 1, the loading amount of polyvinyl acetate was 0.2 g / m². 2 A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that it was applied by spray coating and then dried to form an adhesive layer.

[0144] <Example 4>

[0145] In Example 1, a copolymer of polyvinylidene acetate (PVAc), a second polymer binder, and a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP) (BG4430 of Arkema company), a third polymer binder, were mixed in a weight ratio of 70:30 and added to water, a solvent, to produce the slurry for the adhesive layer. The total loading amount of the copolymer of polyvinylidene acetate (PVAc), polyvinylidene fluoride, and hexafluoropropylene (PVdF-HFP) was 0.5 g / m². 2 A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that it was coated with a bar coating and then dried to form an adhesive layer.

[0146] <Example 5>

[0147] An electrochemical element separation membrane was manufactured in the same manner as in Example 1, except that the adhesive layer slurry was used to form an adhesive layer so that the adhesive polymer binder was provided to 50% of the surface area of ​​the coating layer.

[0148] <Comparative Example 1>

[0149] A porous polymer substrate (total thickness approximately 9 μm) was manufactured by extruding polyethylene resin (weight-average molecular weight 900,000) using a wet process.

[0150] As inorganic particles, Al2O3 powder with a D50 particle size of 600 nm was prepared. As a binder polymer, a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (Solvay, Solef21510) was prepared, and as a dispersant, sodium carboxymethylcellulose (CMC-Na) (SG-L02, GLCHEM) was prepared.

[0151] The inorganic particles, binder polymer, and dispersant prepared above were added to acetone in a weight ratio of 78:20:2, and then the binder polymer was dissolved to produce a slurry for the coating layer.

[0152] A coating slurry was loaded onto both sides of a porous polymer substrate at a loading rate of 3.2 g / m². 2 After applying the material in the desired state, a coating layer was formed using a humidified phase separation method to manufacture a separation membrane for electrochemical elements.

[0153] <Comparative Example 2>

[0154] A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that acrylic resin (LGC, ADS11) was used as the second polymer binder.

[0155] <Comparative Example 3>

[0156] A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that only a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (Arkema, LBG4430LX) was used as the second polymer binder.

[0157] <Comparative Example 4>

[0158] A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that an acrylic resin, acrylate (LGC, ADS11), and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (Arkema, LBG4430LX), were mixed in a weight ratio of 5:5 as the second polymer binder.

[0159] <Comparative Example 5>

[0160] A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that polyolefin wax (Mitsui Chemicals, ChemiPearl W700) was used as the second polymer binder.

[0161] <Comparative Example 6>

[0162] In Example 1, the loading amount of polyvinyl acetate was 1.5 g / m². 2 A separation membrane for an electrochemical element was manufactured in the same manner as in Example 1, except that it was coated with a bar coating and then dried to form an adhesive layer.

[0163] <Manufacturing of electrochemical elements>

[0164] 1) Manufacturing of the positive electrode

[0165] 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 Chem), 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, the remaining components had 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).

[0166] 2) Manufacturing of the negative electrode

[0167] 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, Junsei Co., Ltd., Japan), 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, the remaining components had 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).

[0168] 3) Lamination process

[0169] The separation films of the examples and comparative examples were interposed between the manufactured negative and positive electrodes and laminated, and a lamination process was performed to obtain an electrode assembly. The lamination process was carried out using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0170] <Experimental Example 1: Measurement of thermal shrinkage rate at 180°C>

[0171] The separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut into 50 mm (length) x 50 mm (width) pieces to prepare test specimens. These were then kept in an oven heated to 180°C for 30 minutes, after which the test specimens were collected and subjected to machine-directed (machine) analysis. The length changes with respect to the direction (MD) and the perpendicular direction (TD) were measured, and the thermal shrinkage rate was calculated using the following formula 1 and summarized in Table 1 below. (Math 1) Thermal shrinkage rate at 180°C (%) = {(Dimensions before shrinkage - Dimensions after shrinkage) / Dimensions before shrinkage} × 100

[0172] <Experimental Example 2: Dry Adhesion Measurement>

[0173] The separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut to 70 mm (length) x 25 mm (width), and the prepared negative electrodes and separation membranes were laminated using a press at 60°C, 6.5 MPa, and 1 sec to produce test specimens. The prepared test specimens were attached to a glass plate using double-sided tape, with the negative electrode facing the glass plate. The separation membrane portion of the test specimen was peeled off at a speed of 150 mm / min at 25°C at an angle of 180°, and the strength at this time was measured and summarized in Table 1 below.

[0174] <Experiment Example 3: Wet Adhesion Measurement>

[0175] The separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut to 70 mm (length) x 25 mm (width), and the negative electrodes and separation membranes were laminated using a press at 60°C, 6.5 MPa, and 1 sec to prepare test specimens. The prepared test specimens were placed in a battery case with the electrolyte and maintained for 4 hours to allow the specimens to be impregnated with the electrolyte. The electrolyte used was a mixture of ethylene carbonate and ethyl methyl carbonate in a volume ratio of 7:3, with LiPF6 at a concentration of 1 M. After removing the test specimens from the case, they were attached and fixed to a glass plate using double-sided tape, with the negative electrode facing the glass plate. The separation membrane portion of the test specimen was peeled off at a 90° angle at a speed of 200 mm / min at 25°C, and the strength at this time was measured and summarized in Table 1 below.

[0176] <Experimental Example 4: Measurement of Electrolyte Viscosity>

[0177] The viscosity of the electrolyte in the electrode assemblies containing the separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 was measured at 25°C using a Brookfield LVDV-II+Pro Viscometer (cone-plate type, torque 90%, spindle #42, sample loading volume 1 mL), and the results are summarized in Table 1 below.

[0178] <Experimental Example 5: Measurement of Ionic Conductivity>

[0179] The ionic conductivity of the electrolyte in the electrode assemblies containing the separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 was measured at 25°C using a Mettler Toledo Multiparameter, and the results are summarized in Table 1 below.

[0180] <Experimental Example 6: Measurement of Resistance of Separation Membrane>

[0181] Coin cells were fabricated by interposing each separation membrane between SUS (stainless steel) layers and injecting the electrolyte. The resistance (ER) was measured using the EIS (Electron Inspection System) method and summarized in Table 1 below. The frequency range was set to 100,000 to 10,000 Hz. The electrolyte was a non-aqueous solvent consisting of ethylene carbonate and ethyl methyl carbonate mixed in a 3:7 ratio, to which LiPF6 was added at a concentration of 1 M.

[0182] <Experimental Example 7: Measurement of Room Temperature Cycle Capacity Maintenance Rate>

[0183] The electrochemical elements utilizing the separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were charged and discharged once at 0.1C in the voltage range of 3.0V to 4.4V in a 25°C chamber using an electrochemical charger / discharger. After that, the life characteristics were measured for 200 cycles of charging at 1.0C and discharging at 1.0C. At this time, the life characteristics were expressed as the capacity retention rate calculated using Equation 2 below, by comparing the discharge capacity after 200 cycles to the discharge capacity after the first discharge, and summarized in Table 1 below.

[0184] The capacity retention rate was calculated using the following formula 2. (Math 2) Capacity retention rate (%) = (Discharge capacity after 200 cycles / Discharge capacity after 1 cycle) × 100

[0185] [Table 1]

[0186] Referring to Table 1 above, the adhesive layer contains a polyvinyl acetate resin, and the content of the second polymer binder per unit area of ​​the adhesive layer is 0 g / m². 2 Super 1.2g / m 2 In the following Examples 1 to 4, a separation membrane resistance of 0.75 Ω or less was achieved, and it was confirmed that the room-temperature cycle capacity retention rate was 80% or higher in all cases.

[0187] In contrast, Comparative Example 1, a separation membrane using a humidified phase separation method without another adhesive layer, showed a high thermal shrinkage rate. Comparative Example 2, which contained only an acrylic resin in the adhesive layer, Comparative Example 3, which contained only a copolymer of polyvinylidene fluoride and hexafluoropropylene in the adhesive layer, and Comparative Example 4, which contained both an acrylic resin and a copolymer of polyvinylidene fluoride and hexafluoropropylene, showed increased resistance of the separation membrane and decreased room-temperature cycle capacity retention.

[0188] Furthermore, in Comparative Example 5, which contained polyolefin wax in the adhesive layer, both dry and wet adhesive strengths decreased, and in Comparative Example 6, which contained an excessive amount of polyvinyl acetate resin, separation membrane resistance increased and the room temperature cycle capacity retention rate decreased.

[0189] In summary, the separation membrane for an electrochemical element according to one embodiment of the present invention contains a polyvinyl acetate resin in the adhesive layer, and by adjusting the content of the polyvinyl acetate resin, the separation membrane resistance can be reduced, the room temperature cycle capacity retention rate can be increased, and the battery performance can be improved. [Explanation of symbols]

[0190] 100: Separation membrane for electrochemical elements 110: Porous polymer base material 130: Coating layer 131: First Polymer Binder 133: Inorganic particles 150: Adhesive layer 151: Second Polymer Binder 300: Positive electrode 500: Negative electrode 1000: Electrochemical elements

Claims

1. Porous polymer base material; A coating layer provided on at least one surface of the porous polymer substrate, comprising a first polymer binder and inorganic particles; and An adhesive layer provided on the coating layer, comprising a second polymer binder containing a polyvinyl acetate resin; Includes, The content of the second polymer binder per unit area of ​​the adhesive layer is 0 g / m². ２ Super, 1.5g / m ２ The following: A separation membrane for an electrochemical element, wherein the content of the inorganic particles in the coating layer is 90 parts by weight or more per 100 parts by weight of the coating layer.

2. The content of the second polymer binder per unit area of ​​the adhesive layer is 0.1 g / m². ２ 1.4g / m or more ２ The separation membrane for an electrochemical element according to claim 1 is as follows:

3. The separation membrane for an electrochemical element according to claim 1, wherein the second polymer binder is in the form of particles.

4. The separation membrane for an electrochemical element according to claim 1, wherein the adhesive layer further comprises a third polymer binder containing a polyvinylidene-based binder.

5. The separation membrane for an electrochemical element according to claim 4, wherein the polyvinylidene-based binder is a copolymer of polyvinylidene fluoride and hexafluoropropylene.

6. The separation membrane for an electrochemical element according to claim 4, wherein the weight ratio of the second polymer binder to the third polymer binder in the adhesive layer is 99:1 to 50:

50.

7. The separation membrane for an electrochemical element according to claim 1, wherein the thickness of the coating layer is greater than 0 μm and 2.0 μm or less.

8. It includes a positive electrode; a negative electrode; a separation membrane; and an electrolyte. The separation membrane is interposed between the positive electrode and the negative electrode and is an electrochemical element as described in any one of claims 1 to 7.

9. The electrochemical element according to claim 8, wherein the solubility of the second polymer binder in the electrolyte is 50 (w / w) or more and 80 (w / w) or less at room temperature.

Images