Separation membrane for electrochemical element and electrochemical element including 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 the benefit 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 benefit 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 incorporated herein by reference. The present invention relates to a separator for an electrochemical device and an electrochemical device including the same, and more particularly, to a separator for an electrochemical device and an electrochemical device including the same, which can improve heat resistance and reduce the resistance of a battery by providing an adhesive layer containing a polyvinyl acetate-based resin on a coating layer.

Background Art

[0002] Among the components of an electrochemical device, the separator is disposed between the positive electrode and the negative electrode, includes a polymer substrate having a porous structure, separates the positive electrode and the negative electrode, and serves to prevent an electrical short circuit between the two electrodes and to allow the electrolyte and ions to pass through. The separator itself does not participate in the electrochemical reaction, but physical properties such as wettability with respect to the electrolyte, degree of porosity, and thermal shrinkage rate affect the performance and safety of the electrochemical device.

[0003] Accordingly, various methods have been attempted to add a coating layer to the porous polymer substrate to enhance the physical properties of the separator and to change the physical properties of the coating layer by adding various substances to the coating layer. As an example, an inorganic substance is added to the coating layer to improve the mechanical strength of the separator, or an inorganic substance or hydrate is provided to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0004] The separator can be adhered to the electrode by a lamination process, and a binder resin can be added to the slurry for the coating layer of the separator to ensure the adhesive force between the electrode and the separator.

[0005] On the one hand, existing separator membranes used in medium and large-sized batteries such as EV (Electric Vehicle) and ESS (Energy Storage System) achieve adhesion through a coating method by humid phase separation for the assembly processes of lamination and stacking. Therefore, a high content of PVdF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) is required. However, separator membranes containing a high content of the PVdF-HFP have problems such as a decrease in heat resistance, an increase in particle size in the slurry containing the binder, making it difficult to thin the separator membrane, and it is difficult to ensure the energy density. In addition, in the case of an oil-based binder, since it is soluble in the electrolyte, when an excessive amount of the binder is dissolved in the electrolyte, there are problems such as an increase in the viscosity of the electrolyte, a decrease in ionic conductivity, an increase in resistance, and a decrease in battery performance.

[0006] In the case of a separator membrane containing a high content of inorganic particles in the coating layer, it has the characteristic of excellent heat resistance due to the high content of inorganic substances, and it is possible to thin the separator membrane. However, in the case of a separator membrane containing such a coating layer with a high content of inorganic substances, since there is no adhesive layer on the surface, there is a problem that lamination becomes difficult in the assembly process of manufacturing the battery.

[0007] Therefore, there was a need for research on a separator membrane that can reduce resistance while ensuring adhesiveness and can be thinned.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The technical problem to be solved by the present invention is to overcome the problems of the prior art, achieve a low viscosity of the electrolyte in the battery, improve the performance of the battery, and provide a separator for an electrochemical device by making the separator film thinner, providing an adhesive layer containing a polyvinyl acetate resin on the coating layer, and adjusting the content of the polyvinyl acetate resin provided in the coating layer to adjust the amount of the binder dissolved in the electrolyte. Thereby, while realizing a low viscosity of the electrolyte in the battery, the performance of the battery can be improved and the separator film can be made thinner.

[0009] However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

Means for Solving the Problems

[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. The content of the second polymer binder per unit area of the adhesive layer is more than 0 g / m 2 super, 1.5 g / m 2 The following provides a separator for an electrochemical device. Here, the area means a plane on the separator film viewed from a perspective 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 area of the adhesive layer may be 0.1 g / m 2 or more and 1.4 g / m 2 or less.

[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 with respect to 100 parts by weight of the coating layer.

[0013] According to an embodiment of the present invention, the second polymer binder may be in a particulate form.

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

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

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

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

[0018] According to an embodiment of the present invention, the resistance of the separator for the electrochemical device may be 0.8 Ω or less.

[0019] An embodiment of the present invention provides an electrochemical device including a positive electrode; a negative electrode; a separator; and an electrolyte, wherein the separator is the aforementioned separator for an electrochemical device interposed between the positive electrode and the negative electrode.

[0020] According to an 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.

Advantages of the Invention

[0021] The separator for an electrochemical device according to an embodiment of the present invention can be made thinner to improve the energy density of the battery, and the coating layer including a high content of inorganic particles with an adhesive layer can achieve adhesive strength during the process of manufacturing the battery.

[0022] According to one embodiment of the present invention, an electrochemical element can adjust the solubility of a polymer binder contained in an adhesive layer in an electrolytic solution to reduce the viscosity of the electrolytic solution, improve the ionic conductivity of the battery, and at the same time reduce the surface resistance of the battery.

Brief Description of the Drawings

[0023]

Figure 1

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Embodiments for Carrying Out the Invention

[0024] Hereinafter, various embodiments of the present invention will be described in detail so that an ordinary technician in the technical field 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 content.

[0025] Unless otherwise particularly limited, all detailed descriptions defining or embodying the embodiments are applicable to all inventions and are not limited to the description of a specific invention. That is, the present disclosure also represents combinations of separately disclosed embodiments. Further, unless otherwise expressly stated, throughout the detailed description and the appended claims, the singular forms include the plural forms.

[0026] In this specification, when a part is described as "including" a certain component, this means that, unless otherwise stated to the contrary, it does not exclude other components but can further include other components. However, unless explicitly stated otherwise, terms such as "consisting of" or "including" include "substantially consisting of" and "consisting of".

[0027] As used herein, the term "essentially included" has the meaning of "including 70% or more", preferably "including 80% or more", and most preferably "including 90% or more". When referring to the amount of a component in a mixture of substances, % is the weight % based on the total weight of each mixture. As an example, a substance essentially including polyethylene includes polyethylene in an amount of at least 70% by weight based on 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 situation are given, or are used in substantially the same meaning, and are used to prevent improper use of this specification in which exact or absolute numerical values for the understanding of this specification are described.

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

[0030] In this specification, when it is said that one component is "provided on" another component, this does not exclude the possibility that other components are disposed in between, but rather means that other components can be further disposed, unless otherwise stated to the contrary. However, unless explicitly stated otherwise, "on" means "directly on", that is, it includes the situation where no other components are further disposed in between.

[0031] In this specification, the characteristic of "having pores" means that the object includes a plurality of pores, and a fluid in a gas phase and / or a liquid phase can pass from one side surface to the other side surface of the object through a structure connected between the pores.

[0032] In this specification, the separation membrane has a porous property including a large number of pores, and serves as a porous ion-conducting barrier that allows ions to pass through while blocking electrical contact between the negative electrode and the positive electrode in an electrochemical element.

[0033] Hereinafter, the present invention will be described in more detail.

[0034] One embodiment of the present invention includes a porous polymer substrate 110; a coating layer 130 provided on at least one surface of the porous polymer substrate 110 and including 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 including a second polymer binder 151 containing a polyvinyl acetate (PVAc) resin. The content of the second polymer binder 151 per unit area of the adhesive layer 150 is 0 g / m 2 exceeding 1.5 g / m 2 The separation membrane 100 for an electrochemical element is provided as follows.

[0035] The separation membrane 100 for an electrochemical element according to one embodiment of the present invention can be thinned to improve the energy density of the battery. By having the adhesive layer 150, the coating layer 130 containing a high content of inorganic particles can achieve adhesion during the battery manufacturing process.

[0036] FIG. 1 is a schematic view of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. FIG. 2 is a schematic view of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. Specifically, FIG. 1 is a schematic view of a separation membrane 100 for an electrochemical element provided with a coating layer 130 and an adhesive layer 150 on one surface, and FIG. 2 is a schematic view of a separation membrane 100 for an electrochemical element provided with a coating layer 130 and an adhesive layer 150 on each of both surfaces. With reference to FIGS. 1 and 2, the separation membrane 100 for an electrochemical element according to one embodiment of the present invention will be specifically described.

[0037] According to one embodiment of the present invention, the separation membrane 100 for an electrochemical element includes a porous polymer substrate 110. As described above, since the separation membrane 100 for an electrochemical element includes the porous polymer substrate 110, 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-based resin as a base resin. Examples of polyolefin-based resins include polyethylene, polypropylene, polypentene, etc., and one or more of these may be included. A separation membrane having such porosity, that is, having a large number of pores, manufactured using a polyolefin-based resin as a base resin is advantageous from the viewpoint of imparting a shutdown function at an appropriate temperature.

[0039] According to one embodiment of the present invention, the weight average molecular weight of the polyolefin-based resin may be 500,000 or more and 1,500,000 or less. By adjusting the weight average molecular weight of the polyolefin resin within the above range, the compression resistance of the separation membrane can be improved. Further, when mixing and using different polyolefin-based resins or forming a separation membrane with a multilayer structure composed of different polyolefin-based resins, the weight average molecular weight of the polyolefin-based resin can be calculated by adding the weight average molecular weights according to the content ratios of the respective polyolefin-based resins.

[0040] In this specification, the "weight average molecular weight (Mw)" can be measured by gel permeation chromatography (GPC: gel permeation chromatography, PLGPC220, Agilent Technologies), and the measurement conditions can be set as follows: - Column: PL Olexis (Polymer Laboratories) - Solvent: TCB (Trichlorobenzene) - Flow rate: 1.0 ml / min - Sample concentration: 1.0 mg / ml - Injection volume: 200 μl - Column temperature: 160 °C -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-based resin is kneaded with diluents at a high temperature to form a single phase, the polyolefin-based resin and the diluent are phase-separated during the cooling process, the diluent is extracted to form pores, and then stretching and heat setting treatments are performed.

[0042] According to one embodiment of the present invention, the average pore size and the maximum pore size of the pores of the separation membrane 100 for an electrochemical element can be easily manufactured by those skilled in the art to conform to the scope of the present invention by adjusting the mixing ratio of the diluent, the stretching ratio, the heat setting treatment temperature, and the like.

[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, 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, 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 range, the energy density of the battery can be improved.

[0044] According to an 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-mentioned range, the separation membrane permeability of lithium ions can be adjusted.

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

[0046] In this specification, the porosity and pore size of the porous polymer substrate 110 and / or the coating layer 130 can be measured by the BET point method by the nitrogen gas adsorption flow method using a scanning electron microscope (SEM) image, a mercury porosimeter, a capillary flow porometer, or a porosimetry analyzer (Porosimetry analyzer; Bell Japan Inc, Belsorp-II mini). At this time, it is advantageous to use a capillary flow porometer.

[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 the porous polymer substrate 110 (preferably provided directly). Specifically, the separation membrane 100 for an electrochemical element includes a coating layer 130 provided on one surface of the porous polymer substrate 110 (preferably installed directly) as shown in FIG. 1, or includes a coating layer 130 provided on both surfaces of the porous polymer substrate 110 (preferably installed directly) as shown in FIG. 2. As described above, since the separation membrane 100 for an electrochemical element includes the coating layer 130 provided on at least one surface of the porous polymer substrate 110, the heat resistance of the separation membrane is improved, the mechanical properties are improved, and the separation membrane can be prevented from shrinking at high temperature to cause an electrical short circuit of the electrode.

[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, since the coating layer 130 contains the first polymer binder 131 and the inorganic particles 133, the heat resistance of the separation membrane is improved, the mechanical properties are improved, the separation membrane is prevented from shrinking at high temperature to cause an electrical short circuit of the electrode, and pores can be formed inside the coating layer.

[0049] According to one embodiment of the present invention, the coating layer 130 may include 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 inside. As described above, since the coating layer contains a plurality of pores, lithium ions can pass through while physically blocking the negative electrode and the positive electrode so that an electric current can flow.

[0050] According to one embodiment of the present invention, the coating layer 130 can be formed by the inorganic particles 133 being bound by the first polymer binder 131 and being integrated in the coating layer. The pores inside the coating layer 130 may be caused by the interstitial volume, which is the empty space between the inorganic particles 133.

[0051] According to an 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 foregoing, the heat resistance of the coating layer can be improved, and the bonding strength of the inorganic particles in the coating layer can be improved.

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

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

[0054] According to an embodiment of the present invention, the acrylic-styrene copolymer may contain an acrylic binder, and the acrylic binder may be a polyacrylate type. 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-styrene rubber, and acrylate polymers, and specifically may be a copolymer containing acrylate.

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

[0056] According to an embodiment of the present invention, the first polymer binder 131 may be of a particle type or a liquid type. By selecting the first polymer binder 131 from the foregoing, 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 an embodiment of the present invention, the polyvinylidene (PVdF) - based binder contained in the first polymer binder 131 may have a hexafluoropropylene (HFP) content of 10 wt% or more. Specifically, the polyvinylidene-based binder contained in the first polymer binder 131 may have a hexafluoropropylene content of 10 wt% or more and 80 wt% or less, 15 wt% or more and 75 wt% or less, 20 wt% or more and 70 wt% or less, 25 wt% or more and 65 wt% or less, 30 wt% or more and 60 wt% or less, 35 wt% or more and 55 wt% or less, or 40 wt% or more and 50 wt% or less. By adjusting the content of hexafluoropropylene contained in the polyvinylidene-based binder within the above range in the first polymer binder 131, the resistance of the separation membrane can be reduced. In the polyvinylidene (PVdF) - based binder, the content of the hexafluoropropylene (HFP) monomer is 1 measurable by H - NMR and / or 19 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 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, 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, 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 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 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 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. In the coating layer, the content of the first polymer binder 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 having 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, 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, 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 [[ID=]], the dispersibility in the slurry prepared for the production 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" means 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 (for example, Microtrac S3500). When the particles pass through the laser beam, the difference in the diffraction pattern due to the particle size is measured to calculate the particle size distribution. The D50 particle size can be measured by calculating the particle size at the point where the cumulative particle number distribution by particle size in the measuring device reaches 50%.

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

[0061] According to an embodiment of the present invention, the inorganic particles 133 that can be used for 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 an embodiment of the present invention are not particularly limited as long as oxidation and / or reduction reactions do not occur within the operating voltage range of the applied electrochemical device (e.g., 0 V to 5 V based on Li / Li + reference).

[0062] According to an embodiment of the present invention, when using inorganic particles with a high dielectric constant, the inorganic particles can contribute to an increase in the dissociation of electrolyte salts, such as lithium salts, in the liquid electrolyte and improve the ionic conductivity of the electrolyte solution. For the reasons described above, the inorganic particles may be inorganic particles with a dielectric constant of 5 or more, inorganic particles having lithium ion transport ability, or a mixture thereof.

[0063] According to an embodiment of the present invention, non-limiting examples of the inorganic particles 133 include BaTiO3, Pb(Zr,Ti)O3 (PZT), 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 )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), etc., and one or more of these may be included.

[0064] According to an embodiment of the present invention, there is no particular limitation on the average diameter (D 50 ) of the inorganic particles 133, but it is preferably in the range of 0.3 μm or more and 1 μm or less for forming a coating layer with a uniform thickness and an appropriate porosity. For example, the average diameter (D50 ) may be 0.5 μm or more and 0.7 μm or less, or may be 0.6 μm. Specifically, when it is less than 0.3 μm, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer may decrease, and when it exceeds 1 μm, the thickness of the formed coating layer may increase.

[0065] In this specification, "D 50 particle size" means the particle size at the 50% point of the particle number cumulative 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 measuring device (for example, Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern due to the particle size is measured to calculate the particle size distribution. By calculating the particle size at the point where the particle number cumulative distribution by particle size in the measuring device reaches 50%, the D50 particle size can be measured.

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

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

[0068] According to an embodiment of the present invention, the content of the second polymer binder 151 per unit area of the adhesive layer 150 is 0 g / m 2 exceeding 1.5 g / m 2The following is the case. The content of the second polymer binder 151 per unit area of the adhesive layer 150 is 0.1 g / m 2 or more, 0.2 g / m 2 or more, 0.3 g / m 2 or more, 0.5 g / m 2 or more, 0.8 g / m 2 or more, 0.9 g / m 2 or more may be sufficient. The content of the second polymer binder 151 per unit area of the adhesive layer 150 is 1.4 g / m 2 or less, 1.3 g / m 2 or less, 1.2 g / m 2 or less, 1.1 g / m 2 or less, 1.0 g / m 2 or less may be sufficient. Specifically, the content of the second polymer binder 151 per unit area of the adhesive layer 150 is 0.1 g / m 2 or more and 1.5 g / m 2 or less, 0.2 g / m 2 or more and 1.4 g / m 2 or less, 0.5 g / m 2 or more and 1.3 g / m 2 or less, 0.8 g / m 2 or more and 1.2 g / m 2 or less, 0.9 g / m 2 or more and 1.1 g / m 2 or less may be sufficient. For example, the content of the second polymer binder 151 per area of the adhesive layer 150 may be 0.2 g / m 2 or more and 1.0 g / m 2 or less. By adjusting the content of the second polymer binder 151 per unit area of the adhesive layer 150 within the above-mentioned range, the dissolution amount of the second polymer binder 151 in the electrolytic solution can be reduced, the viscosity of the electrolytic solution can be reduced, thereby the resistance of the separation membrane can be reduced, and the adhesive force can be improved. 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 the slurry for the adhesive layer.

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

[0070] According to an embodiment of the present invention, there is no special limitation on the average diameter (D50) of the second polymer binder 151 particles, but for the formation of the adhesive layer 150 with a uniform thickness and an appropriate porosity, it is preferably in the range of 0.1 μm or more and 1 μm or less. The average diameter (D 50 ) of the second polymer binder 151 particles 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 second polymer binder 151 particles 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 second polymer binder 151 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. By adjusting the average diameter (D 50 ) of the second polymer binder 151 within the above range, the dispersibility in the slurry prepared for the production of the adhesive layer can be improved, and the thickness of the formed adhesive layer can be reduced. In this specification, the "D50 particle size" means the particle size at the 50% point of the cumulative particle number distribution according to the particle size. The particle size can be measured using the laser diffraction method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (for example, Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern due to the particle size is measured to calculate the particle size distribution. The D50 particle size can be measured by calculating the particle size at the point where the cumulative particle number distribution according to the particle size in the measuring device reaches 50%.

[0071] FIG. 3 is a schematic view of the separation membrane 100 for an electrochemical element according to an embodiment of the present invention. FIG. 4 is a schematic view of the separation membrane 100 for an electrochemical element according to an embodiment of the present invention. Specifically, FIG. 3 is a schematic view of the separation membrane 100 for an electrochemical element provided with a coating layer 130 and an adhesive layer 150 on one surface, and the adhesive layer 150 includes a third polymer binder 153. FIG. 4 is a schematic view of the separation membrane 100 for an electrochemical element provided with a coating layer 130 and an adhesive layer 150 on each of both surfaces, and the adhesive layer 150 includes a third polymer binder. With reference to FIGS. 3 and 4, the separation membrane 100 for an electrochemical element according to an embodiment of the present invention will be specifically described.

[0072] According to an embodiment of the present invention, the adhesive layer 150 may further include a third polymer binder 153 including a polyvinylidene-based binder. As described above, by further including the third polymer binder 153 including a polyvinylidene-based binder, it is possible to minimize an increase in resistance due to an electrolytic solution and improve wet adhesive strength.

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

[0074] Specifically, the polyvinylidene-based binder may have a hexafluoropropylene content of more 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 content of hexafluoropropylene contained in the polyvinylidene-based binder within the above range, it is possible to maintain the porosity of the separation membrane and improve the resistance of the separation membrane.

[0075] According to an embodiment of the present invention, the polyvinylidene-based binder may be a polyvinylidene fluoride (PVdF)-based binder. As described above, by selecting the polyvinylidene-based binder as a polyvinylidene fluoride-based 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 an embodiment of the present invention, the polyvinylidene-based binder may be a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-co-HFP, Poly(vinylidene fluoride-co-hexafluoropropylene)). As described above, by selecting the polyvinylidene-based binder as a copolymer of polyvinylidene fluoride and hexafluoropropylene, dissolution of the third polymer binder by the electrolytic solution can be minimized and the wet adhesive force can be improved.

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

[0078] According to an implementation state of the present invention, the weight ratio of the second polymer binder 151 and the third polymer binder 153 in the adhesive layer 150 may be from 99:1 to 50:50. Specifically, the weight ratio of the second polymer binder 151 and the third polymer binder 153 in the adhesive layer 150 may be from 95:5 to 55:45, from 90:10 to 60:40, from 85:15 to 65:35, or from 80:20 to 70:30. Preferably, it may be 70:30. By adjusting the weight ratio of the second polymer binder 151 and the third polymer binder 153 in the adhesive layer 150 within the above range, it is possible to prevent an increase in the resistance of the separation membrane due to the electrolytic solution and at the same time improve the dry adhesive force.

[0079] In this specification, the dry adhesive force means the value measured when a separation film is cut into a size of 70 mm (length) × 25 mm (width), a prepared negative electrode and the separation film are laminated under the conditions of 60°C, 6.5 MPa, and 1 second using a press to produce a test piece, the prepared test piece is adhered and fixed to a glass plate using double-sided tape, and at this time, after arranging the negative electrode to face the glass plate, the separation film portion of the test piece is peeled at an angle of 180° at a speed of 150 mm / min at 25°C, and the strength at this time is measured.

[0080] In this specification, the wet adhesive force means the value measured when a separation film is cut into a size of 70 mm (length) × 25 mm (width), a prepared negative electrode and the separation film are laminated under the conditions of 60°C, 6.5 MPa, and 1 second using a press to produce a test piece, the prepared test piece is placed in a battery case together with an electrolytic solution, maintained for 4 hours to impregnate the test piece with the electrolytic solution (a mixture of ethylene carbonate and ethyl methyl carbonate mixed at a volume ratio of 7:3 and prepared with a concentration of 1 M of LiPF6), and then, after taking out the test piece from the case, it is adhered and fixed to a glass plate using double-sided tape, and at this time, after arranging the negative electrode to face the glass plate, the separation film portion of the test piece is peeled at an angle of 90° at a speed of 200 mm / min at 25°C, and the strength at this time is measured.

[0081] According to an 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 / m 2 more than 1.5 g / m 2 may be as follows. 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 / m 2 or less, 0.2 g / m 2 or less, 0.3 g / m 2 or less, 0.5 g / m 2 or less, 0.8 g / m 2 or less, 0.9 g / m 2 may be as follows. 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 / m 2 or less, 1.3 g / m2 Less than or equal to 1.2 g / m 2 Less than or equal to 1.1 g / m 2 Less than or equal to 1.0 g / m 2 It may also be the following. 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 / m 2 Greater than or equal to 1.5 g / m 2 Less than or equal to 0.3 g / m 2 Greater than or equal to 1.4 g / m 2 Less than or equal to 0.5 g / m 2 Greater than or equal to 1.3 g / m 2 Less than or equal to 0.7 g / m 2 Greater than or equal to 1.2 g / m 2 Less than or equal to or 0.9 g / m 2 Greater than or equal to 1.1 g / m 2 It may also be the following. By adjusting the total content of the second polymer binder and the third polymer binder per unit area of the adhesive layer within the above range, the dissolution amount of the second polymer binder in the electrolytic solution can be reduced, the viscosity of the electrolytic solution can be reduced, thereby the resistance of the separation membrane can be reduced, and the adhesive force can be improved. 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 the slurry for the adhesive layer.

[0082] According to one embodiment of the present invention, the thickness of the coating layer 130 on either one of the porous polymer substrates 110 may be more than 0 μm and 2.0 μm or less. The thickness of the coating layer 130 on either one 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, 1.4 μm or more. The thickness of the coating layer 130 on either one 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, 1.6 μm or less. Specifically, the thickness of the coating layer 130 may be more than 0 μm and 2.0 μm or less, 0.1 μm or more and 1.9 μm or less, 0.2 μm or more and 1.8 μm or less, 0.3 μm or more and 1.7 μm or less, 0.4 μm or more and 1.6 μm or less, 0.5 μm or more and 1.5 μm or less, 0.6 μm or more and 1.4 μm or less, 0.7 μm or more and 1.3 μm or less, 0.8 μm or more and 1.2 μm or less, 0.9 μm or more and 1.1 μm or less. 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 more than 0 μm and 1.0 μm or less. The thickness of the adhesive layer 150 may be 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 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, 0.6 μm or less. Specifically, the thickness of the coating layer 130 may be more than 0 μm and 1.0 μm or less, 0.1 μm or more and 0.9 μm or less, 0.2 μm or more and 0.8 μm or less, 0.3 μm or more and 0.7 μm or less, 0.4 μm or more and 0.6 μm or less. Preferably, it may be 0.5 μm.

[0084] In one embodiment of the present invention, the thickness of the polymer substrate and / or the coating layer and / or the adhesive layer, etc. can be measured by applying a contact thickness measuring instrument. As the contact thickness measuring instrument, for example, VL-50S-B manufactured by Mitutoyo can be used.

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

[0086] In this specification, "resistance" may be a value obtained when a separation membrane is interposed between SUSs, an electrolyte solution in which LiPF6 is mixed at a concentration of 1 M in a non-aqueous solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a ratio of 3:7 is injected, a coin cell is fabricated, and the resistance (ER) is measured by the EIS method. At this time, the frequency may be in the range of 100000 to 10000 Hz.

[0087] According to an embodiment of the present invention, the second polymer binder may be of a particulate type, a soluble type, or a combination thereof. As used herein, "particulate type" means that the second polymer binder maintains the shape of particles because it is not dissolved by the electrolyte injected into the battery. As used herein, "soluble type" means that the second polymer binder cannot maintain the shape of particles because it is dissolved by the electrolyte injected into the battery. By selecting the second polymer binder from the foregoing, the dry adhesion and wet adhesion to the electrode can be improved.

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

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

[0090] According to an embodiment of the present invention, the second polymer binder is provided on a part of the coating layer by a spraying method, bar coating, spin coating, or dip coating method for the coating layer. By selecting a method for providing the adhesive polymer binder from the above-mentioned ones, the adhesive polymer binder can be easily disposed on the coating layer. An embodiment of the present invention includes a step of applying a slurry for a coating layer containing a first polymer binder 131 and inorganic particles 135 on at least one surface of a porous polymer substrate 110 for forming a coating layer; and a step of applying a slurry for an adhesive layer containing a second polymer binder for forming an adhesive layer; and provides a method for manufacturing a separator for an electrochemical element.

[0091] The method for manufacturing an electrochemical element according to an embodiment of the present invention can easily prevent an increase in the resistance of the separator, and can manufacture the separator as a thin film to improve the energy density of the battery. In the method for manufacturing a separator for an electrochemical element according to an embodiment of the present invention, the content overlapping with the description of the separator for an electrochemical element is omitted.

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

[0093] According to an embodiment of the present invention, before 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 a slurry is obtained. As the solvent, those having a solubility index similar to the binder polymer used and a low boiling point are preferable. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of solvents that can be used include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or a mixture thereof. In the present specification, the dispersion medium may mean a solvent as that used in the process of producing the slurry.

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

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

[0096] According to an 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 carboxymethyl cellulose (SG-L02, GLCHEM) as a dispersant. As described above, by further containing a dispersant in the slurry for the coating layer, the dispersibility of the slurry for the coating layer can be improved.

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

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

[0099] According to an embodiment of the present invention, the content of the first polymer binder in the slurry for the coating layer may be 10 parts by weight or less with respect to 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 slurry for the coating layer may be more than 0 part 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 with respect to 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 slurry for the coating layer 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 with respect to 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 slurry for the coating layer may be more than 0 part 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 with respect to 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-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.

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

[0101] According to an embodiment of the present invention, a method for manufacturing an electrochemical device includes a step of applying a slurry for an adhesive layer containing a second polymer binder 151. As described above, by including the step of applying a slurry for an adhesive layer containing the 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 the third polymer binder contained in the adhesive layer) can be easily adjusted.

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

[0103] According to an 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 the slurry for the adhesive layer further containing a solvent, the second polymer binder and the third polymer binder can be uniformly dispersed.

[0104] According to an embodiment of the present invention, the slurry for the adhesive layer may contain a second polymer binder and a solvent. According to an 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 an embodiment of the present invention, the content of the second polymer binder in the slurry for the adhesive layer may be 1 part by weight or more and 99 parts by weight or less with respect to 100 parts by weight of the slurry for the adhesive layer. The content of the second polymer binder in the slurry for the adhesive layer 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 with respect to 100 parts by weight of the slurry for the adhesive layer. The content of the second polymer binder in the slurry for the adhesive layer 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 with respect to 100 parts by weight of the slurry for the adhesive layer. Specifically, the content of the second polymer binder in the slurry for the adhesive layer 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 with respect to 100 parts by weight of the slurry for the adhesive layer. By adjusting the content of the second polymer binder within the above-mentioned range, the viscosity of the electrolytic solution can be reduced, whereby the resistance of the separation membrane can be reduced and the adhesive force can be improved.

[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% by weight or more and 29% by weight or less, 12% by weight or more and 28% by weight or less, 13% by weight or more and 27% by weight or less, 14% by weight or more and 26% by weight or less, 15% by weight or more and 25% by weight or less, 16% by weight or more and 24% by weight or less, 17% by weight or more and 23% by weight or less, 18% by weight or more and 22% by weight or less, or 19% by weight or more and 21% by weight or less. By adjusting the solid content of the slurry for the adhesive layer within the above range, the second polymer binder and the third polymer binder disposed on the coating layer can be easily applied, and the amount to be disposed can be easily adjusted.

[0107] According to one embodiment of the present invention, the method for manufacturing an electrochemical device may include a step of drying the slurry for the coating layer to provide the coating layer. As described above, by including the step of drying the slurry for the coating layer to provide the 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 of the coating layer may be 25°C or more and 75°C or less. Specifically, the temperature of the drying process of the coating 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 of the coating layer within the above range, denaturation of the porous polymer substrate can be prevented, and the dispersion medium can be effectively removed.

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

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

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

[0112] According to an embodiment of the present invention, the drying process appropriately sets the time conditions so as to minimize the occurrence of surface defects in the coating layer. A drying auxiliary device such as a drying oven or hot air may be used within an appropriate range in the drying process.

[0113] According to an embodiment of the present invention, the separator is interposed between the negative electrode and the positive electrode and is manufactured as an electrochemical element by a lamination process in which heat and / or pressure is applied to bond them. In an embodiment of the present invention, the lamination process may be performed by a roll press device including a pair of pressure rollers. That is, the negative electrode, the separator, and the positive electrode can be sequentially laminated and introduced between the pressure rollers to achieve interlayer bonding. At this time, the lamination process can be performed by a hot pressing method.

[0114] An embodiment of the present invention provides an electrochemical element 1000 including a positive electrode 300; a negative electrode 500; a separator 100; and an electrolyte, wherein the separator 100 is the separator 100 for the electrochemical element interposed between the positive electrode 300 and the negative electrode 500.

[0115] The electrochemical element according to an embodiment of the present invention can adjust the solubility of the polymer binder contained in the adhesive layer in the electrolyte to lower the viscosity of the electrolyte, improve the ionic conductivity of the battery, and at the same time lower the surface resistance of the battery.

[0116] FIG. 5 is a schematic diagram of an electrochemical element 1000 according to an embodiment of the present invention. With reference to FIG. 5, the electrochemical element 1000 according to an embodiment of the present invention will be specifically described.

[0117] In an embodiment of the present invention, an electrochemical element is a device that converts chemical energy into electrical energy by an electrochemical reaction, and is a concept including a primary battery and a secondary battery. In this specification, a secondary battery can be charged and discharged, and means a lithium secondary battery, a nickel-cadmium battery, a nickel-hydrogen battery, etc. In the lithium secondary battery, lithium ions are used as an ion conductor, and examples include a non-aqueous electrolyte secondary battery including a liquid electrolyte, an all-solid battery including a solid electrolyte, a lithium polymer battery including a gel polymer electrolyte, and a lithium metal battery using lithium metal as a negative electrode, but are not limited thereto.

[0118] According to one embodiment of the present invention, the positive electrode has a positive electrode active material layer including a positive electrode current collector and a positive electrode active material, a conductive material, and a binder resin on at least one surface of the positive electrode current collector. The positive electrode active material may include 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 O4 (where x is 0 to 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; scientific formula LiNi 1-x M x O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga, and x = 0.01 to 0.3), Ni-site type lithium nickel oxide represented by; chemical formula LiMn 1-x M x O2 (where M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1) or lithium manganese composite oxide represented by 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 compound; one or a mixture of two or more of Fe2(MoO4)3 may be included.

[0119] According to one embodiment of the present invention, the negative electrode has a negative electrode active material layer including a negative electrode current collector and a negative electrode active material, a conductive material, and a binder resin on at least one surface of the negative electrode current collector. The negative electrode includes carbon such as lithium metal oxide, graphitizable carbon, 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; may contain one or a mixture of two or more selected from titanium oxides.

[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 selected from the group consisting of natural graphite, artificial graphite, 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 a chemical change 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, as the binder resin, a polymer commonly used for electrodes in the art may be used. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-cotrichloroethylene, polymethylmethacrylate, polyetylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylprrolidone, pollyvinylacetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, cellulose acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose, etc., and is not limited thereto.

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

[0125] According to one 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 Chemical Co., Ltd., Japan).

[0126] According to one embodiment of the present invention, the content of the dispersant contained in the negative electrode slurry may be more than 0 part by weight and 0.5 part 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 part by weight and 0.4 part by weight or less with respect to 100 parts by weight of the negative electrode slurry.

[0127] According to one embodiment of the present invention, the electrochemical element prepared as described above can be housed in an appropriate case and an electrolytic solution can be injected to manufacture a battery.

[0128] According to one embodiment of the present invention, the electrolytic solution 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 these or combinations thereof are dissolved or dissociated in an organic solvent consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran , N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone (γ-butyrolactone) or mixtures thereof, but are not limited thereto.

[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 means the amount of the second polymer binder dissolved in 100 g of the electrolyte at room temperature (solute = second polymer binder, solvent = electrolyte). 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, 59 (w / w)% It may be 60 (w / w)% or more, 61 (w / w)% or more, 62 (w / w)% or more, 63 (w / w)% or more, 64 (w / w)% or more. The solubility of the second polymer binder in the electrolyte may be 79 (w / w)% or less, 78 (w / w)% or less, 77 (w / w)% or less, 76 (w / w)% or less, 75 (w / w)% or less, 74 (w / w)% or less, 73 (w / w)% or less, 72 (w / w)% or less, 71 (w / w)% or less, 70 (w / w)% or less, 69 (w / w)% or less, 68 (w / w)% or less, 67 (w / w)% or less, 66 (w / w)% or less at room temperature (25°C). Specifically, the solubility of the second polymer binder in the electrolyte may be 51 (w / w)% or more and 79 (w / w)% or less, 52 (w / w)% or more and 78 (w / w)% or less, 53 (w / w)% or more and 77 (w / w)% or less, 54 (w / w)% or more and 76 (w / w)% or less, 55 (w / w)% or more and 75 (w / w)% or less, 56 (w / w)% or more and 74 (w / w)% or less, 57 (w / w)% or more and 73 (w / w)% or less, 58 (w / w)% or more and 72 (w / w)% or less, 59 (w / w)% or more and 71 (w / w)% or less, 60 (w / w)% or more and 70 (w / w)% or less, 61 (w / w)% or more and 69 (w / w)% or less, 62 (w / w)% or more and 68 (w / w)% or less, 63 (w / w)% or more and 67 (w / w)% or less, 64 (w / w)% or more and 66 (w / w)% or less. By adjusting the solubility of the second polymer binder in the electrolyte within the above range, it is possible to prevent the second polymer from being dissolved in the electrolyte and increasing the viscosity of the electrolyte, and to improve the resistance increase of the separation membrane and the ionic conductivity.

[0130] According to an 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 means the amount of the third polymer binder dissolved in 100 g of the electrolyte at room temperature (solute = third polymer binder, solvent = electrolyte). 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, 59 (w / w)% or more, 60 (w / w)% or more, 61 (w / w)% or more, 62 (w / w)% or more, 63 (w / w)% or more, 64 (w / w)% or more at room temperature (25 °C). The solubility of the third polymer binder in the electrolyte is 79 (w / w)% or less, 78 (w / w)% or less, 77 (w / w)% or less, 76 (w / w)% or less, 75 (w / w)% or less, 74 (w / w)% or less, 73 (w / w)% or less, 72 (w / w)% or less, 71 (w / w)% or less, 70 (w / w)% or less, 69 (w / w)% or less, 68 (w / w)% or less, 67 (w / w)% or less, 66 (w / w)% or less at room temperature (25 °C). Specifically, the solubility of the third polymer binder in the electrolyte is 51 (w / w)% or more and 79 (w / w)% or less, 52 (w / w)% or more and 78 (w / w)% or less, 53 (w / w)% or more and 77 (w / w)% or less, 54 (w / w)% or more and 76 (w / w)% or less, 55 (w / w)% or more and 75 (w / w)% or less, 56 (w / w)% or more and 74 (w / w)% or less, 57 (w / w)% or more and 73 (w / w)% or less, 58 (w / w)% or more and 72 (w / w)% or less, 59 (w / w)% or more and 71 (w / w)% or less, 60 (w / w)% or more and 70 (w / w)% or less, 61 (w / w)% or more and 69 (w / w)% or less, 62 (w / w)% or more and 68 (w / w)% or less, 63 (w / w)% or more and 67 (w / w)% or less, 64 (w / w)% or more and 66 (w / w)% or less at room temperature. By adjusting the solubility of the third polymer binder in the electrolyte within the above-mentioned range, it is possible to prevent the third polymer from being dissolved in the electrolyte and increasing the viscosity of the electrolyte, and to improve the resistance increase and ion conductivity of the separation membrane.

[0131] One embodiment of the present invention provides a battery module including 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 a power tool powered by a battery motor; an electric vehicle including an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), a Plug-in Hybrid Electric Vehicle (PHEV), etc.; an electric two-wheeler including an electric bicycle (E-bike), an electric scooter (E-scooter), etc., an electric golf cart, a power storage system, etc., but are not limited thereto.

Example

[0132] Hereinafter, examples will be given for a specific description of the present invention. However, the examples according to the present invention can be deformed into various different forms, and the scope of the present invention is not construed as being limited to the examples described later. The examples in this specification are provided to more fully explain the present invention to those with average knowledge in the industry.

[0133] <Example 1>

[0134] Polyethylene resin (weight average molecular weight 9 million) was extruded to produce a porous polymer substrate (total thickness of about 9 μm, porosity of 40% by volume) by a wet method.

[0135] As inorganic particles, Al2O3 powder having a particle size of 600 nm was prepared. As the first binder polymer, an acrylic emulsion (CSB-130, Toyo Ink Co., Ltd.) was prepared, and as a dispersant, sodium carboxymethyl cellulose (CMC-Na) (SG-L02, GLCHEM Co., Ltd.) was prepared. 50

[0136] ​The prepared inorganic particles, the first binder polymer, and the dispersant were added to water as the dispersion medium at a weight ratio of 97:2:1, and then the inorganic particles were crushed and dispersed to produce a slurry for the coating layer.

[0137] The slurry for the coating layer was coated on each of the two sides of the porous polymer substrate and dried to form a coating layer.

[0138] Polyvinyl acetate as the second polymer binder was added to water as the solvent and dispersed so that the solid content was 20% by weight to produce a slurry for the adhesive layer.

[0139] The slurry for the adhesive layer was applied onto the coating layer by bar coating so that the loading amount of polyvinyl acetate (average particle diameter (D50) of the particles: 500 nm) was 1.0 g / m 2 and then dried to form an adhesive layer, thereby producing a separation membrane for an electrochemical device.

[0140] <Example 2>

[0141] In Example 1, a separation membrane for an electrochemical device was produced in the same manner as in Example 1, except that after applying by bar coating so that the loading amount of polyvinyl acetate was 0.5 g / m 2 it was dried to form an adhesive layer.

[0142] <Example 3>

[0143] In Example 1, a separation membrane for an electrochemical device was produced in the same manner as in Example 1, except that after applying by spray coating so that the loading amount of polyvinyl acetate was 0.2 g / m 2 it was dried to form an adhesive layer.

[0144] <Example 4>

[0145] In Example 1, polyvinyl acetate (PVAc), which is the second polymer binder, and a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP) (BG4430 of Arkema company), which is the third polymer binder, were mixed at a weight ratio of 70:30 and added to water as a solvent to produce the slurry for the adhesive layer. After that, except that the total loading amount of the copolymer of polyvinylidene acetate (PVAc), polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) became 0.5 g / m 2 An electrochemical element separation membrane was produced in the same manner as in Example 1, except that after coating by bar coating so as to obtain this, and drying to form an adhesive layer.

[0146] <Example 5>

[0147] An electrochemical element separation membrane was produced in the same manner as in Example 1, except that in Example 1, an adhesive layer was formed so that an adhesive polymer binder was provided in an area of 50% on the coating layer to produce an electrochemical element separation membrane.

[0148] <Comparative Example 1>

[0149] A polyethylene resin (weight average molecular weight: 900,000) was extruded to produce a porous polymer base material (total thickness: about 9 μm) by a wet method.

[0150] As inorganic particles, Al2O3 powder having 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 carboxymethyl cellulose (CMC-Na) (SG-L02, GLCHEM) was prepared.

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

[0152] A coating layer slurry was applied to both sides of the porous polymer substrate so that the loading amount was 3.2 g / m 2 After that, a coating layer was formed using the humidification phase separation method to produce a separation membrane for an electrochemical device.

[0153] <Comparative Example 2>

[0154] In Example 1, a separation membrane for an electrochemical device was produced in the same manner as in Example 1, except that acrylate (LGC, ADS11), which is an acrylic resin, was used as the second polymer binder.

[0155] <Comparative Example 3>

[0156] In Example 1, a separation membrane for an electrochemical device was produced 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] In Example 1, a separation membrane for an electrochemical device was produced in the same manner as in Example 1, except that acrylate (LGC, ADS11), which is an acrylic resin, and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP) (Arkema, LBG4430LX) were mixed and used at a weight ratio of 5:5 as the second polymer binder.

[0159] <Comparative Example 5>

[0160] In Example 1, a separation membrane for an electrochemical device was produced in the same manner as in Example 1, except that polyolefin wax (Mitsui Chemicals, Chemipar W700) was used as the second polymer binder.

[0161] <Comparative Example 6>

[0162] In Example 1, except that after coating by bar coating so that the loading amount of polyvinyl acetate becomes 1.5 g / m 2 and then drying to form an adhesive layer, a separation membrane for an electrochemical device was produced in the same manner as in Example 1.

[0163] <Manufacture of Electrochemical Device>

[0164] 1) Manufacture of positive electrode

[0165] A positive electrode active material (LiNi 0.8 Mn 0.1 Co 0.1 O2), a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chem), and a binder resin (mixture of PVdF-HFP and PVDF) were mixed with water at a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a positive electrode active material layer with the remaining components excluding water having 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) Manufacture of negative electrode

[0167] Graphite (mixture of natural graphite and artificial graphite), a conductive material (carbon black), a dispersant (Polyvinylpyrrolidone, Junsei, Japan), and a binder resin (mixture of PVdF-HFP and PVDF) were mixed with water at a weight ratio of 97.5:0.7:0.14:1.66 to prepare a slurry for a negative electrode active material layer with the remaining components excluding water having a concentration of 50 wt%. Next, the slurry was applied to the surface of a copper thin film (thickness 10 μm) and dried to produce a negative electrode having a negative electrode active material layer (thickness 120 μm).

[0168] 3) Lamination process

[0169] The separator membranes of the examples and comparative examples were interposed between the manufactured negative electrode and positive electrode and laminated, and a lamination process was carried out to obtain an electrode assembly. The lamination process was carried out for 10 seconds under the conditions of 70 °C and 5.2 MPa using hot pressing.

[0170] <Experimental Example 1: Measurement of Thermal Shrinkage Rate at 180 °C>

[0171] The separator membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut into a size of 50 mm (length) × 50 mm (width) to prepare test pieces, which were maintained in an oven heated to 180 °C for 30 minutes. Thereafter, the test pieces were recovered, and the lengths changed in the machine direction (MD) and the transverse direction (TD) were measured, and the thermal shrinkage rate was calculated by the following formula (1) and summarized in Table 1 below. The lengths changed in the machine direction (MD) and the transverse direction (TD) were measured, and the thermal shrinkage rate was calculated by the following formula (1) and summarized in Table 1 below. (Equation 1) Thermal shrinkage rate at 180 °C (%) = {(dimension before shrinkage - dimension after shrinkage) / dimension before shrinkage} × 100

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

[0173] The separator membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut into 70 mm (length) × 25 mm (width), and the prepared negative electrode and the separator membrane were laminated using pressing under the conditions of 60 °C, 6.5 MPa, and 1 second to produce test pieces. The prepared test pieces were attached and fixed to a glass plate using double-sided tape. At this time, the negative electrode was arranged so as to face the glass plate. The separator membrane portion of the test piece was peeled at an angle of 180° at a speed of 150 mm / min at 25 °C, and the strength at this time was measured and summarized in Table 1 below.

[0174] <Experimental Example 3: Measurement of Wet Adhesion Strength>

[0175] The separator membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were cut into pieces of 70 mm (length) × 25 mm (width), and the prepared negative electrode and the separator membrane were laminated at 60 °C, 6.5 MPa, and for 1 second using pressing to fabricate test pieces. The prepared test pieces were placed in a battery case together with an electrolytic solution and maintained for 4 hours to impregnate the test pieces with the electrolytic solution. As the electrolytic solution, ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 7:3, and a solution prepared with a concentration of 1 M LiPF6 was used. Then, after the test pieces were taken out of the case, they were attached and fixed to a glass plate using double-sided tape. At this time, the negative electrodes were arranged so as to face the glass plate. The separator membrane portion of the test piece was peeled at an angle of 90° 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 Viscosity of Electrolytic Solution>

[0177] In the electrode assemblies including the separator membranes of Examples 1 to 5 and Comparative Examples 1 to 5, the viscosity of the electrolytic solution was measured at 25 °C using a Brookfield LVDV-II+Pro Viscometer (cone-plate type), torque 90%, spindle #42, and sample loading amount of 1 mL, and then summarized in Table 1 below.

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

[0179] In the electrode assemblies including the separator membranes of Examples 1 to 5 and Comparative Examples 1 to 5, the ionic conductivities of the electrolytic solutions were measured at 25 °C using a Mettler Toledo Multiparameter equipment, respectively, and then summarized in Table 1 below.

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

[0181] Each separation membrane was interposed between SUS, and an electrolytic solution was injected to fabricate a coin cell. The resistance (ER) was measured by the EIS method and summarized in Table 1 below. At that time, the frequency was in the range of 100,000 to 10,000 Hz. The electrolytic solution is a non-aqueous solvent in which ethylene carbonate and ethyl methyl carbonate are mixed at a ratio of 3:7, and LiPF6 is mixed at a concentration of 1 M.

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

[0183] The electrochemical elements using the separation membranes of Examples 1 to 5 and Comparative Examples 1 to 5 were charged and discharged once at 0.1 C in the voltage range of 3.0 V to 4.4 V in a 25 °C chamber using an electrochemical charger / discharger, and then the life characteristics were measured while performing 1.0 C charging and 1.0 C discharging for 200 cycles. At this time, the life characteristics were shown as the ratio of the discharge capacity after 200 cycles to the discharge capacity after the first cycle by the calculation of the following formula 2, and summarized in Table 1 below.

[0184] The capacity retention rate was calculated by the following formula 2. (Equation 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-based resin, and the content of the second polymer binder per unit area of the adhesive layer is 0 g / m 2 exceeding 1.2 g / m 2 In Examples 1 to 4 below, it was confirmed that the separation membrane resistance was 0.75 Ω or less, and the room temperature cycle capacity retention rates were all 80% or more.

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

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

[0189] In summary, the separation membrane for an electrochemical device according to an embodiment of the present invention contains a polyvinyl acetate-based resin in the adhesive layer. By adjusting the content of the polyvinyl acetate-based resin, the separation membrane resistance decreases, the normal temperature cycle capacity retention rate increases, and the battery performance can be improved.

Explanation of symbols

[0190] 100: Separation membrane for electrochemical device 110: Porous polymer substrate 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 device

Claims

1. A porous polymer substrate; A coating layer provided on at least one surface of the porous polymer substrate, the coating layer containing a first polymer binder and inorganic particles; and An adhesive layer provided on the coating layer, the adhesive layer containing a second polymer binder containing a polyvinyl acetate-based resin; comprising The content of the second polymer binder per unit area of the adhesive layer is more than 0 g / m ２ 2 and less than or equal to 1.5 g / m ２ 2. The separation membrane for an electrochemical device is as follows.

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

3. The content of the inorganic particles in the coating layer is 90 parts by weight or more with respect to 100 parts by weight of the coating layer. The separation membrane for an electrochemical element according to Claim 1.

4. The second polymer binder is of a particulate type. The separation membrane for an electrochemical element according to Claim 1.

5. The adhesive layer further contains a third polymer binder containing a polyvinylidene-based binder. The separation membrane for an electrochemical element according to Claim 1.

6. The polyvinylidene-based binder is a copolymer of polyvinylidene fluoride and hexafluoropropylene. The separation membrane for an electrochemical element according to Claim 5.

7. The weight ratio of the second polymer binder to the third polymer binder in the adhesive layer is from 99:1 to 50:

50. The separation membrane for an electrochemical element according to Claim 5.

8. The thickness of the coating layer is more than 0 μm and 2.0 μm or less. The separation membrane for an electrochemical element according to Claim 1.

9. The resistance of the separation membrane for an electrochemical element is 0.80 Ω or less. The separation membrane for an electrochemical element according to Claim 1.

10. Comprising a positive electrode; a negative electrode; a separation membrane; and an electrolytic solution, The separation membrane is interposed between the positive electrode and the negative electrode and is the separation membrane for an electrochemical element according to any one of Claims 1 to 9. An electrochemical element.

11. The solubility of the second polymer binder in the electrolytic solution is 50 (w / w)% or more and 80 (w / w)% or less at room temperature. The electrochemical element according to Claim 10.

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