Separation membrane for electrochemical elements, and electrochemical elements containing the same

Abstract

The present invention relates to a separation membrane for electrochemical elements and an electrochemical element containing the same. Specifically, by including a plate-type silicate composition in the coating layer, the dispersibility of the slurry for the coating layer can be improved, and the uniformity of the coating layer can be enhanced.

Description

[Technical Field]

[0001] This invention claims the benefits as of the filing date of Korean Patent Application No. 10-2023-0088117, filed with the Korean Intellectual Property Office on July 7, 2023, and all of its contents are included in this invention.

[0002] The present invention relates to a separation membrane for an electrochemical element and an electrochemical element containing the same, and more specifically, to a separation membrane for an electrochemical element that can improve the dispersibility of the coating layer slurry and improve the uniformity of the coating layer by including a plate-type silicate composition in the coating layer, and an electrochemical element containing the same. [Background technology]

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

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

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

[0006] On the other hand, the slurry for the coating layer produced during the manufacturing process of the separation membrane has low viscosity, and when left or stored at room temperature, inorganic substances precipitate. In order to uniformly disperse the precipitated inorganic substances again in the coating layer slurry, further stirring is required, which presents a problem.

[0007] Therefore, rather than the viscosity of the coating layer slurry increasing under both low and high shear conditions, there was a need for a separation membrane in which the viscosity of the coating layer slurry increased mainly under low shear conditions, thereby improving phase stability when stored at room temperature. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The technical problem that the present invention aims to solve is to provide a separation membrane for an electrochemical element, and an electrochemical element containing the same, in which the uniformity of the separation membrane can be improved by adjusting the components and content of the plate-type silicate composition contained in the coating layer of the separation membrane.

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

[0010] One embodiment of the present invention provides a separation membrane for an electrochemical element, comprising a porous polymer substrate and a coating layer provided on at least one surface of the porous polymer substrate, the coating layer comprising a plate-type silicate composition, polymer binder particles, and inorganic particles, wherein the plate-type silicate composition comprises one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof.

[0011] According to one embodiment of the present invention, the plate-type silicate composition may contain SiO2 in an amount of 50% by weight or more and 60% by weight or less.

[0012] According to one embodiment of the present invention, the plate-type silicate composition may contain MgO in an amount of 22% by weight or more and 28% by weight or less.

[0013] According to one embodiment of the present invention, the plate-type silicate composition may contain Li2O in an amount of 0.5% by weight or more and 2.0% by weight or less.

[0014] According to one embodiment of the present invention, the plate-type silicate composition may contain Na2O in an amount of 2.0% by weight or more and 8.0% by weight or less.

[0015] According to one embodiment of the present invention, in the plate-type silicate composition, the SiO2 may be contained in an amount of 65% to 80% by weight, the MgO in an amount of 10% to 20% by weight, the Li2O in an amount of 0.5% to 2.0% by weight, and the Na2O in an amount of 9% to 20% by weight.

[0016] According to one embodiment of the present invention, in the plate-type silicate composition, the SiO2 may be contained in an amount of 70% to 75% by weight, the MgO in an amount of 13% to 18% by weight, the Li2O in an amount of 1.0% to 1.5% by weight, and the Na2O in an amount of 12.0% to 18.0% by weight.

[0017] According to one embodiment of the present invention, in the plate-type silicate composition, the SiO2 may be contained in an amount of 71% to 74% by weight, the MgO in an amount of 13% to 16% by weight, the Li2O in an amount of 1.1% to 1.4% by weight, and the Na2O in an amount of 14.0% to 16.0% by weight.

[0018] According to one embodiment of the present invention, the content of the plate-type silicate composition may be 0.1 parts by weight or more and 1.0 part by weight or less per 100 parts by weight of the coating layer.

[0019] According to one embodiment of the present invention, the specific surface area of ​​the plate-type silicate composition is 250 m². 2 / g or more 400m 2 It may be less than / g.

[0020] According to one embodiment of the present invention, the density of the plate-type silicate composition is 900 kg / m³. 3 ~1050 kg / m 3 It is possible.

[0021] According to one embodiment of the present invention, the pH of an aqueous suspension containing 2% by weight of the plate-type silicate composition may be 8.0 or higher and 12.0 or lower.

[0022] According to one embodiment of the present invention, the plate-type silicate composition may further include one selected from the group consisting of P2O5, F, and combinations thereof.

[0023] According to one embodiment of the present invention, the plate-like silicate composition may be laponite.

[0024] One embodiment of the present invention provides an electrochemical element comprising a positive electrode, a negative electrode, and a separation membrane for the electrochemical element interposed between the positive electrode and the negative electrode. [Effects of the Invention]

[0025] A separation membrane for an electrochemical element according to one embodiment of the present invention can prevent the non-uniform distribution of components contained in the coating layer and improve the uniformity of the separation membrane.

[0026] An electrochemical element according to one embodiment of the present invention can improve the uniformity of the coating layer and enhance the performance of the battery. [Brief explanation of the drawing]

[0027] [Figure 1]This is a schematic diagram of a separation membrane for an electrochemical element according to one embodiment of the present invention. (a) is a schematic diagram of a separation membrane for an electrochemical element having a coating layer on one surface, and (b) is a schematic diagram of a separation membrane for an electrochemical element having coating layers on both sides. [Figure 2] This is a schematic diagram of an electrochemical element relating to one embodiment of the present invention. [Modes for carrying out the invention]

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

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

[0030] In this specification, when we say that a component is "placed on top of" another component, this means that, unless otherwise stated, other components may be placed in between, rather than excluding the possibility of other components being placed in between.

[0031] In this specification, the characteristic of "having pores" means that the object contains multiple pores, and that a gaseous and / or liquid fluid can pass from one side of the object to the other through a structure in which the pores are interconnected.

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

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

[0034] One embodiment of the present invention provides a separation membrane 100 for an electrochemical element, comprising a porous polymer substrate 110 and a coating layer 130 provided on at least one surface of the porous polymer substrate 110, the coating layer comprising a plate-type silicate composition, polymer binder particles, and inorganic particles, wherein the plate-type silicate composition comprises one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof.

[0035] The separation membrane 100 for an electrochemical element according to one embodiment of the present invention can prevent the components contained in the coating layer 130 from being unevenly distributed, thereby improving the uniformity of the separation membrane.

[0036] Figures 1a and 1b are schematic diagrams of an electrochemical element separation membrane 100 according to one embodiment of the present invention. Specifically, Figure 1a is a schematic diagram of an electrochemical element separation membrane 100 having a coating layer on one surface, and Figure 1b is a schematic diagram of an electrochemical element separation membrane 100 having coating layers on both sides. An electrochemical element separation membrane 100 according to one embodiment of the present invention will be specifically described with reference to Figure 1.

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

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

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

[0040] In this specification, weight-average molecular weight (Mw) can be measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies), and the measurement conditions can be set as follows.

[0041] - Column: PL Olexis (Polymer Laboratories Inc.) - Solvent: TCB (Trichlorobenzene) -Flow rate: 1.0ml / min -Sample concentration: 1.0 mg / ml -Injection volume: 200μl - Column temperature: 160℃ -Detector: Agilent High Temperature RI detector - Standard: Polystyrene (corrected with a cubic function) In this specification, the glass transition temperature can be measured using a differential scanning calorimetry (DSC). Specifically, the glass transition temperature can be measured using a differential scanning calorimetry at a heating rate of 10°C (-50°C to 250°C). For example, the glass transition temperature can be measured using a DSC250 (TA Corporation).

[0042] According to one embodiment of the present invention, the porous polymer substrate 110 may be manufactured by a method (wet method) in which a polyolefin resin is kneaded with a plasticizer (diluents) at a high temperature to form a single phase, the polymer material and the plasticizer are separated during the cooling process, the plasticizer is extracted to form pores, and then stretching and heat-fixing treatment are performed. Furthermore, the porous polymer substrate using a polyolefin resin may comprise a core portion which is a mixture of polyethylene and polypropylene, and polyethylene skin portions which are laminated on both sides of the core portion.

[0043] According to one embodiment of the present invention, the average size and maximum size of the pores of the porous polymer substrate 110 can be easily manufactured to suit the scope of the present invention by adjusting the mixing ratio of the plasticizer, the stretching ratio, and the heat-setting treatment temperature, etc., for the benefit of those skilled in the art.

[0044] 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. 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.

[0045] According to one embodiment of the present invention, the porosity of the porous polymer substrate 110 may be 10% by volume or more and 90% by volume or less. 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 range, the permeability of the lithium ion separation membrane can be adjusted.

[0046] According to one embodiment of the present invention, the coating layer 130 is provided on at least one surface of the porous polymer substrate 110. Specifically, as shown in Figure 1a, the separation membrane 100 for the electrochemical element may include a coating layer 130 provided on one surface of the porous polymer substrate 110. Also, as shown in Figure 1b, the separation membrane 100 for the electrochemical element may include a coating layer 130 provided on both sides of the porous polymer substrate 110. As described above, by including a coating layer 130 provided on at least one surface of the porous polymer substrate 110 in the separation membrane 100, the heat resistance of the separation membrane can be improved, its mechanical properties can be improved, and the occurrence of electrical short circuits of electrodes due to shrinkage of the separation membrane at high temperatures can be prevented.

[0047] According to one embodiment of the present invention, the content of the inorganic particles in the coating layer 130 may be 60 parts by weight or more and 99 parts by weight or less per 100 parts by weight of the coating layer 130. Specifically, the content of the inorganic particles in the coating layer 130 may be 61 to 98 parts by weight, 62 to 97 parts by weight, 63 to 96 parts by weight, 64 to 95 parts by weight, 65 to 94 parts by weight, 66 to 93 parts by weight, 67 to 92 parts by weight, 68 to 91 parts by weight, 69 to 90 parts by weight, 70 to 89 parts by weight, 71 to 88 parts by weight, 72 to 87 parts by weight, 73 to 86 parts by weight, 74 to 85 parts by weight, 75 to 84 parts by weight, 76 to 83 parts by weight, 77 to 82 parts by weight, 78 to 81 parts by weight, or 79 to 80 parts by weight per 100 parts by weight of the coating layer 130. By adjusting the amount of inorganic particles contained in the coating layer 130 within the range described above, phase separation of the polymer binder and inorganic particles can be realized within the coating layer. This allows for different amounts of inorganic particles and / or polymer binder in the coating layer, or by providing an excess of polymer binder in the surface portion of the coating layer compared to the other portion, thereby improving adhesion to the electrodes. Furthermore, by improving the heat resistance of the separation membrane, the safety of the battery can be ensured.

[0048] According to one embodiment of the present invention, the coating layer 130 comprises a plate-type silicate composition, polymer binder particles, and inorganic particles. As described above, by comprising a plate-type silicate composition, polymer binder particles, and inorganic particles in the coating layer, the dispersibility of the polymer binder particles and the inorganic particles can be improved, thereby forming a coating layer with a uniform surface.

[0049] According to one embodiment of the present invention, the plate-type silicate composition comprises one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof. In this specification, the plate-type silicate composition may mean one in which the silicate has a plate-like structure. As described above, by comprising one selected from the group consisting of SiO2, MgO, Li2O, Na2O, and combinations thereof in the plate-type silicate composition, the uniformity of the coating layer can be improved, the surface of the separation film can be uniformly realized, and the dielectric breakdown voltage can be improved.

[0050] According to one embodiment of the present invention, the plate-type silicate composition may contain SiO2 in an amount of 50% to 60% by weight. Specifically, the SiO2 content in the plate-type silicate composition may be 51% to 59% by weight, 52% to 58% by weight, 53% to 57% by weight, or 54% to 56% by weight. By adjusting the SiO2 content within the above ranges, the dispersibility of the coating layer slurry can be improved and phase separation can be prevented.

[0051] According to one embodiment of the present invention, the plate-type silicate composition may contain MgO in an amount of 22% to 28% by weight. Specifically, the MgO content in the plate-type silicate composition may be 23% to 27% by weight, or 24% to 26% by weight. By adjusting the MgO content within the above range, the dispersibility of the coating layer slurry can be improved and phase separation can be prevented.

[0052] According to one embodiment of the present invention, the plate-type silicate composition may contain Li2O in an amount of 0.5% by weight or more and 2.0% by weight or less. Specifically, the Li2O content in the plate-type silicate composition may be 0.6% by weight or more and 1.9% by weight or less, 0.7% by weight or more and 1.8% by weight or less, 0.8% by weight or more and 1.7% by weight or less, 0.9% by weight or more and 1.6% by weight or less, 1.0% by weight or more and 1.5% by weight or less, 1.1% by weight or more and 1.4% by weight or less, or 1.2% by weight or more and 1.3% by weight or less. By adjusting the Li2O content within the above range, the dispersibility of the coating layer slurry can be improved and phase separation can be prevented.

[0053] According to one embodiment of the present invention, the plate-type silicate composition may contain Na2O in an amount of 2.0% to 8.0% by weight. Specifically, the Na2O content in the plate-type silicate composition may be 3.0% to 7.0% by weight, or 4.0% to 6.0% by weight. By adjusting the Na2O content within the above range, the dispersibility of the coating layer slurry can be improved and phase separation can be prevented.

[0054] According to one embodiment of the present invention, the plate-type silicate composition may contain SiO2 in an amount of 65% to 80% by weight, MgO in an amount of 10% to 20% by weight, Li2O in an amount of 0.5% to 2.0% by weight, and Na2O in an amount of 9% to 20% by weight. Specifically, the plate-type silicate composition may contain SiO2 in an amount of 70% to 75% by weight, MgO in an amount of 13% to 18% by weight, Li2O in an amount of 1.0% to 1.5% by weight, and Na2O in an amount of 12.0% to 18.0% by weight. More specifically, according to one embodiment of the present invention, the plate-type silicate composition may contain SiO2 in an amount of 71% to 74% by weight, MgO in an amount of 13% to 16% by weight, Li2O in an amount of 1.1% to 1.4% by weight, and Na2O in an amount of 14.0% to 16.0% by weight. By adjusting the respective contents of SiO2, MgO, Li2O, and Na2O in the plate-type silicate composition within the above range, the dispersibility of the coating layer slurry can be improved and phase separation can be prevented.

[0055] According to one embodiment of the present invention, the content of the plate-type silicate composition may be 0.1 parts by weight or more and 1.0 part by weight or less per 100 parts by weight of the coating layer. Specifically, the content of the plate-type silicate composition may be 0.2 parts by weight or more and 0.9 parts by weight or less, 0.3 parts by weight or more and 0.8 parts by weight or less, 0.4 parts by weight or more and 0.7 parts by weight or less, or 0.5 parts by weight or more and 0.6 parts by weight or less per 100 parts by weight of the coating layer. By adjusting the content of the plate-type silicate composition within the above range, the dispersibility of the slurry for the coating layer can be improved and phase separation can be prevented.

[0056] According to one embodiment of the present invention, the specific surface area of ​​the plate-type silicate composition is 250 m². 2 / g or more 400m 2It may be below / g. Specifically, the specific surface area of the plate-shaped silicate-based composition is 260 m 2 / g or more and 390 m 2 / g or less, 270 m 2 / g or more and 380 m 2 / g or less, 280 m 2 / g or more and 370 m 2 / g or less, 290 m 2 / g or more and 360 m 2 / g or less, 300 m 2 / g or more and 350 m 2 / g or less, 310 m 2 / g or more and 340 m 2 / g or less, or 20 m 2 / g or more and 330 m 2 / g or less. By adjusting the specific surface area of the plate-shaped silicate-based composition within the above-described range, the dispersibility of the plate-shaped silicate-based composition itself can be improved, and the uniformity of the coating layer can be increased.

[0057] In this specification, the "specific surface area" may be the BET surface area calculated using the Brunauer-Emmett-Teller model (BET) from the measured N2 adsorption isotherm when the adsorption isotherm is measured up to 1 bar at -196 °C using a BET-specific surface area analyzer (BEL, Microtrac).

[0058] According to one embodiment of the present invention, the density of the plate-shaped silicate-based composition may be 900 kg / m 3 ~1050 kg / m 3 The density of the plate-shaped silicate-based composition may be from 910 kg / m 3 ~1040 kg / m 3 from 920 kg / m 3 ~1030 kg / m 3 from 930 kg / m 3 ~1020 kg / m 3 from 940 kg / m 3 ~1,010 kg / m 3 from 950 kg / m 3 ~1000 kg / m 3, 960 kg / m 3 ~990 kg / m 3 , or 970 kg / m 3 ~980 kg / m 3 This is possible. By adjusting the density of the plate-type silicate composition within the range described above, the weight of the coating layer can be reduced, and the energy density of the separation membrane can be improved.

[0059] According to one embodiment of the present invention, the pH of an aqueous suspension containing 1% to 3% by weight of the plate-shaped silicate composition may be between 8.0 and 12.0. Specifically, the pH of an aqueous suspension containing 2% by weight of the plate-shaped silicate composition may be between 8.0 and 12.0. In this specification, an aqueous suspension may mean a solution in which particles are dispersed using water as the dispersion medium. An aqueous suspension containing 2% by weight of the plate-shaped silicate composition may mean a solution obtained by mixing and dispersing 98% by weight of water, which is the dispersion medium, with 2% by weight of the plate-shaped silicate composition, which is the particle. Specifically, the pH of an aqueous suspension containing 2% by weight of the plate-shaped silicate composition may be between 8.5 and 10.5, or between 9.0 and 10.0. By adjusting the pH of an aqueous suspension containing 2% by weight of the plate-shaped silicate composition within the above range, it is possible to prevent the degradation of the polymer binder particles contained in the coating layer slurry.

[0060] According to one embodiment of the present invention, the plate-type silicate composition may further include one selected from the group consisting of P2O5, F, and combinations thereof. As described above, by further including one selected from the group consisting of P2O5, F, and combinations thereof in the plate-type silicate composition, the uniformity of the coating layer can be improved, the surface of the separation film can be uniformly realized, and the dielectric breakdown voltage can be improved.

[0061] According to one embodiment of the present invention, the plate-type silicate composition may be laponite. As described above, by selecting laponite as the plate-type silicate composition, the uniformity of the coating layer can be improved, the surface of the separation film can be uniformly realized, and the dielectric breakdown voltage can be improved.

[0062] According to one embodiment of the present invention, the coating layer 130 may contain a plurality of pores. Specifically, the coating layer may be a porous coating layer. More specifically, the coating layer may be a porous coating layer containing a plurality of pores inside. As described above, by the coating layer containing a plurality of pores, lithium ions can pass through and current can flow while physically separating the negative electrode and the positive electrode.

[0063] According to one embodiment of the present invention, the coating layer 130 may be formed by inorganic particles being bound together by polymer binder particles and accumulating within the coating layer. Pores inside the coating layer 130 may be due to interstitial volume, which is the empty space between the inorganic particles.

[0064] According to one embodiment of the present invention, the thickness of the coating layer 130 can be formed with a thickness of 1 μm to 20 μm on either of the porous polymer substrates 110. By adjusting the thickness of the coating layer 130 within the above range, the heat resistance and electrical resistance of the separation membrane can be adjusted to an appropriate range.

[0065] In one embodiment of the present invention, the thickness of the porous polymer substrate 110 and / or the coating layer 130 can be measured using a contact-type thickness gauge. For example, the VL-50S-B from Mitutoyo can be used as the contact-type thickness gauge.

[0066] According to one embodiment of the present invention, the polymer binder particles 133 may be one selected from the group consisting of acrylic binders, polyvinylidene binders, and combinations thereof. The combination of the acrylic binder and the polyvinylidene binder may be a mixture of the acrylic binder and the polyvinylidene binder, a copolymer containing the acrylic repeating units and the polyvinylidene repeating units, or a hybrid of the acrylic binder and the polyvinylidene binder. The polyvinylidene binder may be a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP). By selecting the polymer binder particles from the above, the porosity of the separation membrane can be maintained, the adhesion between the electrodes and the separation membrane can be improved in the battery lamination process, making it easier to manufacture batteries and enabling stable implementation of the stacking process. Furthermore, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated. In addition, the stiffness of the battery can be improved, and bending of the separation membrane can be prevented.

[0067] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, and is preferably a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0068] According to one embodiment of the present invention, specific examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylate Examples include decyl acrylate, hydroxymethyl methacrylate, hydroxyethyl methacrylate, ethylene glycol methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, allyl methacrylate, and ethylene dimethacrylate, and one or more of these can be selected. Of these, one or more selected from methyl methacrylate, ethyl methacrylate, and 2-ethylhexyl methacrylate is preferred, and methyl methacrylate is particularly preferred.

[0069] According to one embodiment of the present invention, the acrylic-styrene copolymer may contain an acrylic binder, and the acrylic binder may be polyacrylate-based. For example, the acrylic binder may be one or more selected from the group consisting of styrene-butyl acrylate, styrene-butadiene rubber, nitril-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, it may be a copolymer containing acrylate.

[0070] According to one embodiment of the present invention, the glass transition temperature (Tg) of the polymer binder particles 133 may be 20°C or more and 60°C or less. Specifically, the glass transition temperature (Tg) of the polymer binder particles may be 22°C or more and 58°C or less, 24°C or more and 56°C or less, 26°C or more and 54°C or less, 28°C or more and 52°C or less, 30°C or more and 50°C or less, 32°C or more and 48°C or less, 34°C or more and 46°C or less, 36°C or more and 44°C or less, or 38°C or more and 42°C or less. By adjusting the glass transition temperature (Tg) of the polymer binder particles within the above range, the viscosity of the slurry for manufacturing the coating layer can be adjusted, thereby improving the convenience of battery manufacturing.

[0071] In this specification, the glass transition temperature can be measured using a differential scanning calorimetry (DSC). Specifically, the glass transition temperature can be measured using a differential scanning calorimetry at a heating rate of 10°C (-50°C to 250°C). For example, the glass transition temperature can be measured using a DSC250 (TA Corporation).

[0072] According to one embodiment of the present invention, the average diameter (D) of the polymer binder particles 133 is 50 There are no particular restrictions on the average diameter (D) of the polymer binder particles 135, but it is preferable that it be in the range of 0.1 μm to 1 μm in order to form a coating layer 130 of uniform thickness and to have an appropriate porosity. Specifically, the average diameter (D) of the polymer binder particles 135 is 50 The average diameter (D) of the polymer binder particles 133 within the above range may be 0.2 μm to 0.9 μm, 0.3 μm to 0.8 μm, 0.4 μm to 0.7 μm, or 0.5 μm to 0.6 μm. 50 By adjusting the ), the dispersibility of the slurry prepared for manufacturing the coating layer can be improved, and the thickness of the formed coating layer can be reduced.

[0073] According to one embodiment of the present invention, the sphericity of the polymer binder particles 133 may be 0.90 or more and 0.99 or less. Specifically, the sphericity of the polymer binder particles 133 may be 0.94 or more and 0.96 or less. In this specification, sphericity may be the ratio of the shortest distance to the longest distance among two points where a straight line passing through the particle intersects the surface of the particle. By adjusting the sphericity of the polymer binder particles within the above range, the dispersion of the polymer binder particles in the slurry within the coating layer can be improved, the size of the polymer binder particles can be adjusted to uniformly realize the surface of the coating layer, reduce roughness, and prevent pressure from concentrating only in specific parts of the coating layer.

[0074] According to one embodiment of the present invention, the density of the polymer binder particles 133 is 1.0 g / cm³. 3 More than 2.0g / cm 3 The following is possible. Specifically, the density of the polymer binder particles 133 is 1.3 g / cm³. 3 More than 1.7g / cm 3 The following is possible: By adjusting the density of the polymer binder particles 133 within the range described above, the layer separation effect between the polymer binder particles and the inorganic particles can be improved, and the adhesion to the electrode can be improved as the polymer binder particles are positioned in excess on the surface of the coating layer compared to the inorganic particles.

[0075] According to one embodiment of the present invention, the polyvinylidene binder may be a polyvinylidene binder having a hexafluoropropylene (HFP) content of 1% to 50% by weight. Specifically, the hexafluoropropylene (HFP) content in the polyvinylidene binder may be 1% to 50% by weight, 2% to 45% by weight, 3% to 40% by weight, 4% to 35% by weight, 5% to 30% by weight, 7% to 25% by weight, or 10% to 20% by weight. As described above, by selecting a polyvinylidene binder having a hexafluoropropylene content of 1% to 50% by weight, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated. In this specification, the degree of substitution of a polyvinylidene-based binder may mean the weight ratio containing hexafluoropropylene.

[0076] According to one embodiment of the present invention, the content of the polymer binder particles may be 1 part by weight or more and 40 parts by weight or less per 100 parts by weight of the coating layer 130. Specifically, the content of the polymer binder particles may be 2 to 39 parts by weight, 3 to 38 parts by weight, 4 to 37 parts by weight, 5 to 36 parts by weight, 6 to 35 parts by weight, 7 to 34 parts by weight, 8 to 33 parts by weight, 9 to 32 parts by weight, 10 to 31 parts by weight, 11 to 30 parts by weight, 12 to 29 parts by weight, 13 to 28 parts by weight, 14 to 27 parts by weight, 15 to 26 parts by weight, 16 to 25 parts by weight, 17 to 24 parts by weight, 18 to 23 parts by weight, 19 to 22 parts by weight, or 20 to 21 parts by weight, per 100 parts by weight of the coating layer 130. By adjusting the content of the polymer binder particles within the range described above, the ease of assembly in the electrode assembly process can be improved.

[0077] According to one embodiment of the present invention, the weight ratio of the acrylic binder and the polyvinylidene binder in the coating layer 130 can be 9:1 to 1:9. Specifically, when the acrylic binder and the polyvinylidene binder are combined in the coating layer 130, the weight ratio can be 8:1 to 1:8, 7:1 to 1:7, 6:1 to 1:6, 5:1 to 1:5, 4:1 to 1:4, 3:1 to 1:3, or 2:1 to 1:2. By adjusting the weight ratio of the acrylic binder and the polyvinylidene binder within the above range, the wet and dry adhesive strength of the separation membrane for the electrochemical element can be improved simultaneously.

[0078] According to one embodiment of the present invention, the inorganic particles that can be used in the coating layer 130 are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are within the operating voltage range of the electrochemical element to which they are applied (e.g., Li / Li + There are no particular restrictions as long as oxidation and / or reduction reactions do not occur between 0V and 5V (based on the specified voltage).

[0079] According to one embodiment of the present invention, non-limiting examples of the inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3 Examples include O3-PbTiO3 (PMN-PT), hafnia (HfO2), SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, ZrO2, SiO2, Y2O3, Al2O3, SiC, Al(OH)3, TiO2, aluminum peroxide, zinc-tin hydroxide (ZnSn(OH)6), tin-zinc oxide (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), and one or more of these may be included.

[0080] According to one embodiment of the present invention, the average diameter (D) of inorganic particles 50 There are no particular restrictions on the average diameter (D) of the inorganic particles, but it is preferable that it be in the range of 0.3 μm to 1 μm in order to form a coating layer 130 of uniform thickness and to have an appropriate porosity. Specifically, the average diameter (D) of the inorganic particles 50 The particle size may be between 0.2 μm and 0.9 μm, between 0.3 μm and 0.8 μm, between 0.4 μm and 0.7 μm, or between 0.5 μm and 0.6 μm. Specifically, if it is less than 0.3 μm, the dispersibility of inorganic particles in the slurry prepared for manufacturing the coating layer may decrease, and if it exceeds 1 μm, the thickness of the formed coating layer may increase.

[0081] In this specification, "D 50 "Particle size" refers to the particle size at the 50% point of the cumulative distribution of particle numbers corresponding to the particle size. The particle size can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in diffraction patterns according to the particle size as the particles pass through the laser beam. By calculating the particle diameter at the point where the cumulative distribution of particle numbers corresponding to the particle size in the measuring device reaches 50%, D 50 It is possible to measure particle size.

[0082] According to one embodiment of the present invention, the porosity of the coating layer 130 may be 30 volume% or more. Specifically, the porosity of the coating layer 130 may be 30 volume% to 70 volume%, 32 volume% to 68 volume%, 34 volume% to 66 volume%, 36 volume% to 64 volume%, 38 volume% to 62 volume%, 40 volume% to 60 volume%, 42 volume% to 58 volume%, 44 volume% to 56 volume%, 46 volume% to 54 volume%, or 48 volume% to 52 volume%. By adjusting the porosity of the coating layer 130 within the above range, it is possible to maintain ion movement in the separation membrane and prevent an increase in the resistance of the separation membrane. Specifically, when the porosity is 70 volume% or less, it is possible to ensure mechanical properties that can withstand the pressing process for bonding with electrodes, and the surface opening ratio does not become too high, which is suitable for ensuring adhesive strength. On the other hand, a porosity of 30% by volume or more is advantageous from the viewpoint of ion permeability.

[0083] In this specification, "porosity" refers to the ratio of the volume occupied by pores to the total volume, and is expressed in units of volume %. It can be used interchangeably with terms such as void ratio and porosity.

[0084] In this specification, porosity may correspond to the subtraction value obtained by subtracting the volume of each component of the porous polymer substrate 110 and / or coating layer 130 converted to weight and density from the volume calculated in terms of thickness, width, and length of the porous polymer substrate 110 and / or coating layer 130.

[0085] In one embodiment of the present invention, the porosity and pore size of the porous polymer substrate 110 and / or the coating layer 130 can be measured by the BET 6-point method using a scanning electron microscope (SEM) image, a mercury porosimeter, a capillary flow porometer, or a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini) by nitrogen gas adsorption flow method. In this case, using a capillary flow porometer may be advantageous.

[0086] One embodiment of the present invention provides a method for producing a separation membrane for an electrochemical element, comprising the steps of: mixing a slurry for a coating layer 130 containing a plate-type silicate composition, polymer binder particles, and inorganic particles (S10); applying the slurry for the coating layer onto at least one surface of a porous polymer substrate 110 (S30); and drying the slurry for the coating layer to form a coating layer 130 (S50).

[0087] A method for manufacturing a separation membrane for an electrochemical element according to one embodiment of the present invention can maintain adhesion during the lamination process with the electrode, improve stiffness by maintaining adhesion after battery activation, and prevent bending of pouch-type cells. Furthermore, it can improve the insulating and thermal conductivity characteristics of the separation membrane and improve the uniformity of the coating layer. In addition, it can improve the dispersibility of particles dispersed in the slurry for the coating layer, preventing phase separation even when stored or left unattended for a long time.

[0088] According to one embodiment of the present invention, the method for manufacturing the separation membrane 100 for the electrochemical element includes a step (S10) of mixing a slurry for a coating layer containing a plate-type silicate composition, polymer binder particles, and inorganic particles. As described above, by including the step (S10) of mixing a slurry for a coating layer containing a plate-type silicate composition, polymer binder particles, and inorganic particles, a coating layer can be easily formed on the separation membrane.

[0089] According to one embodiment of the present invention, a polymer emulsion may be produced by dispersing polymer binder particles in water, which is a suitable dispersion medium, to provide a slurry for the coating layer. As described above, by producing a polymer emulsion by dispersing polymer binder particles in water, which is a suitable dispersion medium, to provide a slurry for the coating layer, contaminants generated during the manufacturing process can be minimized. In this specification, the dispersion medium is used in the process of producing the slurry and may mean a solvent or a dispersion medium.

[0090] According to one embodiment of the present invention, inorganic particles can be added to and dispersed in the polymer emulsion. The content ratio of inorganic particles to polymer binder particles is as described above and is appropriately adjusted considering the thickness, pore size, and porosity of the coating layer produced by the final embodiment of the present invention.

[0091] According to one embodiment of the present invention, the plate-type silicate composition can be further added to a polymer emulsion in which inorganic particles and polymer binder particles are dispersed. As described above, by further adding the plate-type silicate composition to a polymer emulsion in which inorganic particles and polymer binder particles are dispersed, the dispersibility of the polymer binder particles and inorganic particles in the polymer emulsion can be improved, thereby preventing phase separation of the coating layer slurry and improving storage stability.

[0092] According to one embodiment of the present invention, the inorganic emulsion may further contain a dispersant. Specifically, the dispersant may be a polyacrylic acid-based dispersant. As described above, by further including a polyacrylic acid-based dispersant in the inorganic emulsion, the degree of dispersion of inorganic particles dispersed in the inorganic emulsion can be improved, the dispersed inorganic particles are not contained in specific parts, the resistance of the separation film is reduced, and the uniformity of the coating layer can be improved.

[0093] According to one embodiment of the present invention, the dispersant may be more than 0% by weight and 5% by weight or less in the inorganic emulsion. Specifically, the dispersant may be 1% by weight or more and 2% by weight or less in the inorganic emulsion. By adjusting the content of the dispersant within the above range, it is possible to prevent the coating layer from being altered by the dispersant and to improve the degree of dispersion of the inorganic particles.

[0094] According to one embodiment of the present invention, a slurry for a coating layer can be produced by dispersing the plate-type silicate composition, polymer binder particles, and inorganic particles in water, which is a dispersion medium. Specifically, the slurry for a coating layer may be produced by adding an aqueous suspension containing the plate-type silicate composition to the inorganic emulsion.

[0095] According to one embodiment of the present invention, the inorganic particles may be present in the inorganic emulsion at a concentration of 10% to 50% by weight. Specifically, the inorganic particles may be present in the inorganic emulsion at a concentration of 20% to 35% by weight. By adjusting the inorganic particle content within the above range, the heat resistance of the separation membrane can be improved, thereby ensuring the safety of the battery.

[0096] According to one embodiment of the present invention, the content of the dispersion medium may be 30% by weight or more and 70% by weight or less in the inorganic emulsion. Specifically, the content of water, which is the dispersion medium, may be 40% by weight or more and 60% by weight or less in the inorganic emulsion. By adjusting the content of the dispersion medium within the above range, the viscosity of the coating layer slurry can be adjusted to maintain a specific shape and thickness when applying the coating layer.

[0097] According to one embodiment of the present invention, the solid content of the inorganic emulsion may be 10% by weight or more and 50% by weight or less. Specifically, the solid content of the inorganic emulsion may be 15% by weight or more and 40% by weight or less, 20% by weight or more and 35% by weight or less, or 15% by weight or more and 40% by weight or less. By adjusting the solid content of the inorganic emulsion within the above range, the workability of the manufacturing process of the coating layer can be improved.

[0098] According to one embodiment of the present invention, the content of the polymer binder particles may be 10% by weight or more and 30% by weight or less in the inorganic emulsion. Specifically, the content of the polymer binder particles may be 15% by weight or more and 25% by weight or less in the inorganic emulsion. By adjusting the content of the polymer binder particles within the above range, the ease of assembly in the electrode assembly process can be improved, and the binding force between the inorganic particles can be improved, thereby improving the physical rigidity of the coating layer.

[0099] According to one embodiment of the present invention, the content of the surfactant may be 0.1% by weight or more and 2% by weight or less of the inorganic emulsion. Specifically, the content of the surfactant may be 0.1% by weight or more and 1% by weight or less of the inorganic emulsion. By adjusting the content of the surfactant within the above range, each component in the coating layer slurry can be uniformly mixed.

[0100] According to one embodiment of the present invention, in the slurry for the coating layer, the plate-type silicate composition can be added as an aqueous suspension containing 2% by weight of the plate-type silicate composition. Furthermore, in the slurry for the coating layer, the content of the aqueous suspension containing 2% by weight of the plate-type silicate composition may be 10 to 20 parts by weight per 100 parts by weight of the inorganic emulsion. Specifically, in the slurry for the coating layer, the content of the aqueous suspension containing 2% by weight of the plate-type silicate composition may be 13 to 17 parts by weight per 100 parts by weight of the inorganic emulsion. By adjusting the content of the aqueous suspension containing 2% by weight of the plate-type silicate composition in the slurry for the coating layer within the above range, the surface of the separation membrane can be uniformly realized and the dielectric breakdown voltage can be improved.

[0101] According to one embodiment of the present invention, the method for manufacturing the separation membrane 100 for the electrochemical element includes the step (S30) of applying the coating layer slurry onto at least one surface of the porous polymer substrate 110. As described above, by including the step of applying the coating layer slurry onto at least one surface of the porous polymer substrate 110, the coating layer 130 can be formed in a single application. Due to the separation of inorganic particles and polymer binder particles in the coating layer slurry, the portion of the material far from the porous polymer substrate 110, compared to the portion close to the porous polymer substrate 110, has an excess of polymer binder particles 133, which can improve adhesion to the electrode and improve the porosity of the separation membrane. In this specification, the portion close to the porous polymer substrate 110 (part of the coating layer) and the portion far from it (other parts of the coating layer) may be distinguished based on a hypothetical surface that occupies half the thickness of the coating layer.

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

[0103] According to one embodiment of the present invention, the method for manufacturing the separation membrane 100 for the electrochemical element includes the step (S50) of drying the slurry for the coating layer to provide the coating layer 130. As described above, by including the step (S50) of drying the slurry for the coating layer to provide the coating layer 130, damage to the coating layer can be minimized and the dispersion medium contained in the slurry can be easily removed.

[0104] According to one embodiment of the present invention, the temperature of the drying process may be 25°C or more and 75°C or less. Specifically, the temperature of the drying process 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 within the above ranges, modification of the porous polymer substrate can be prevented and the dispersion medium can be effectively removed.

[0105] According to one embodiment of the present invention, the drying process is configured to appropriately set time conditions in order to minimize the occurrence of surface defects in the coating layer 130. The drying can be performed using drying aids such as a drying oven or hot air within an appropriate range.

[0106] According to one embodiment of the present invention, the separation membrane 100 is interposed between the positive electrode 300 and the negative electrode 500 and manufactured as an electrochemical element 1000 by a lamination process in which heat and / or pressure is applied to bond them together. In one embodiment of the present invention, the lamination process can be carried out by a roll press device including a pair of pressure rollers. That is, the negative electrode 500, the separation membrane 100 and the positive electrode 300 can be sequentially laminated and placed between the pressure rollers to achieve interlayer bonding. In this case, the lamination process can be carried out by a hot pressurization method.

[0107] One embodiment of the present invention provides an electrochemical element 1000 comprising a positive electrode 300; a negative electrode 500; and a separation membrane 100 interposed between the positive electrode 300 and the negative electrode 500.

[0108] An electrochemical element 1000 according to one embodiment of the present invention can improve the performance of a battery by improving the uniformity of the coating layer 130.

[0109] Figure 2 is a schematic diagram of an electrochemical element 1000 according to one embodiment of the present invention. The electrochemical element 1000 according to one embodiment of the present invention will be described in detail with reference to Figure 2.

[0110] In one embodiment of the present invention, the electrochemical element is a device that converts chemical energy into electrical energy by an electrochemical reaction, and comprises a primary battery and a secondary battery (Secondary This is a comprehensive concept encompassing batteries. In this specification, the secondary battery is a rechargeable and dischargeable battery, and means lithium secondary batteries, nickel-cadmium batteries, nickel-metal hydride batteries, etc. The lithium secondary battery uses lithium ions as an ion conductor and is not limited to, but includes, non-aqueous electrolyte secondary batteries containing a liquid electrolyte, all-solid-state batteries containing a solid electrolyte, lithium polymer batteries containing a gel polymer electrolyte, and lithium metal batteries using lithium metal as the negative electrode.

[0111] According to one embodiment of the present invention, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer on at least one surface of the current collector, comprising a positive electrode active material, a conductive material, and a binder resin. The positive electrode active material is a layered compound such as lithium manganese composite oxide (LiMn2O4, LiMnO2, etc.), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented as O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and x = 0.01 to 0.3); chemical formula LiMn 1-x M x Lithium manganese composite oxides represented as O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and x = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; and mixtures of one or more of Fe2(MoO4)3 may be included.

[0112] According to one embodiment of the present invention, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer on at least one surface of the current collector, comprising a negative electrode active material, a conductive material, and a binder resin. The negative electrode comprises carbon such as lithium metal oxide, non-graphitizable carbon, and graphite-based carbon as the negative electrode active material; Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2(0≦x≦1), Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8), etc. metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; and one or more mixtures selected from titanium oxides can be included.

[0113] According to an embodiment of the present invention, the conductive material can 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 can be one selected from the group consisting of natural graphite, artificial graphite, super-p, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, denka black, aluminum powder, nickel powder, zinc oxide, potassium titanate, and titanium oxide, or a mixture of two or more of these conductive materials.

[0114] According to an embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery. For example, stainless steel, copper, aluminum, nickel, titanium, fired carbon, or those surface-treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used.

[0115] According to one embodiment of the present invention, the binder resin can be a polymer commonly used in electrodes in the industry. Non-limiting examples of such binder resins include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethyl methacrylate, polyethylhexyl acrylate, polybutyl acrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyethylene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Examples include, but are not limited to, acetatepropionate, cyanoethylpullulan, cyanoethylpolyvinyl alcohol, cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methylcellulose.

[0116] According to one embodiment of the present invention, the cathode slurry for producing the cathode active material layer may contain a dispersant, and the dispersant may be a pyrrolidone compound. Specifically, it may be N-methylpyrrolidone (ADC-01, LG Chemicals).

[0117] According to one embodiment of the present invention, the content of the dispersant in the positive electrode slurry may be more than 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the positive electrode slurry. Specifically, the content of the dispersant in the positive electrode slurry may be more than 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the positive electrode slurry.

[0118] According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may contain a dispersant, and the dispersant may be a polypyrrolidone compound. Specifically, the dispersant may be polyvinylpyrrolidone (Junsei Corporation).

[0119] According to one embodiment of the present invention, the content of the dispersant contained in the negative electrode slurry may be more than 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the negative electrode slurry. Specifically, the content of the dispersant contained in the negative electrode slurry may be more than 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the negative electrode slurry.

[0120] According to one embodiment of the present invention, the electrochemical element prepared as described above can be placed in a suitable case and an electrolyte solution injected to manufacture a battery.

[0121] According to one embodiment of the present invention, the electrolyte is A + B - A salt with a structure like this, + Li + na + , K + It contains alkali metal cations such as, or ions consisting of combinations thereof, B - PF6- BF4 - Cl - , Br - , I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as those listed above, or ions consisting of combinations thereof, may be dissolved or dissociated in organic solvents consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone (γ-butyrolactone), or mixtures thereof, but are not limited to these.

[0122] One embodiment of the present invention provides a battery module including a battery containing the electrochemical element as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to, a power tool powered by a battery motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems. [Examples]

[0123] The present invention will be described in detail below with reference to examples. However, the examples of the present invention can be modified into various different forms, and the scope of the present invention should not be construed as being limited to the examples described below. The examples herein are provided to give a more complete explanation of the present invention to a person of average skill in the art.

[0124] <Example 1> A mixture (solid content 20% by weight) was prepared by dispersing inorganic particles (Al2O3, particle size: 430 nm) and a dispersant (polyacrylic acid-based dispersant, Lubrizol, CK-7058) in water. Subsequently, styrene-butyl acrylate (styrene-butyl acrylate) with a particle size of 350 nm (glass transition temperature 40°C, sphericity 0.95, density 1.5 g / cm³) was added to the mixture as a polymer binder particle. 3 An inorganic emulsion was prepared by adding a surfactant (BYK, BYK-346) and stirring at a speed of 800 rpm to 1000 rpm for 10 minutes. The inorganic emulsion prepared contained 24% by weight of inorganic particles, 1.4% by weight of the dispersant, 17% by weight of the polymer binder particles, 0.1% by weight of the surfactant, and 57.5% by weight of water.

[0125] Separately, a laponite (density: 1000 kg / m³) containing SiO2, 59.5% by weight, MgO, 27.5% by weight, Li2O, 0.8% by weight, and Na2O, as a plate-type silicate composition. 3 , specific surface area: 370m 2 A small amount of the substance ( / g, pH (on a 2 wt% aqueous suspension) = 9.8) was added to the water used as the dispersion medium, and a 2 wt% aqueous suspension was prepared at 1500 rpm until clear.

[0126] After passing the aqueous suspension through a filter having a 400 mesh size, 15 parts by weight of the aqueous suspension was added to 100 parts by weight of the inorganic emulsion containing the polymer binder particles and the surfactant, and the mixture was stirred at a speed of 800 rpm to 1000 rpm for 10 minutes to produce a slurry for the coating layer.

[0127] <Example 2> In Example 1 above, as the plate-shaped silicate-based composition, laponite containing SiO2, 55.0 wt%, MgO, 27.0 wt%, Li2O, 1.4 wt%, Na2O, 3.8 wt%, and F, 5.6 wt% (density: 1000 kg / m 3 , specific surface area: 330 m 2 / g, pH (on a 2 wt% aqueous suspension) = 9.4) was gradually added to water as the dispersion medium, and a slurry for the coating layer was produced in the same manner as in Example 1 except that a 2 wt% aqueous suspension was used until it became transparent at 1500 rpm.

[0128] <Example 3> In Example 1 above, as the plate-shaped silicate-based composition, laponite containing SiO2, 50.2 wt%, MgO, 22.2 wt%, Li2O, 1.2 wt%, Na2O, 7.5 wt%, P2O5, 5.4 wt%, and F, 4.8 wt% (density: 950 kg / m 3 , specific surface area: 300 m 2 / g, pH (on a 2 wt% aqueous suspension) = 10.0) was gradually added to water as the dispersion medium, and a slurry for the coating layer was produced in the same manner as in Example 1 except that a 2 wt% aqueous suspension was used until it became transparent at 1500 rpm.

[0129] <Example 4> In Example 1 above, as the plate-shaped silicate-based composition, laponite containing SiO2, 59.5 wt%, MgO, 27.5 wt%, Li2O, 0.8 wt%, Na2O, 1.8 wt% (density: 1000 kg / m 3 , specific surface area: 370 m 2A coating layer slurry was produced in the same manner as in Example 1, except that / g, pH (on a 2 wt% aqueous suspension) = 9.8) was used.

[0130] <Example 5> In Example 1, as the plate-like silicate-based composition, laponite containing 59.5 wt% SiO2, 27.5 wt% MgO, 0.8 wt% Li2O, 8.5 wt% Na2O (density: 1000 kg / m 3 , specific surface area: 370 m 2 / g, pH (on a 2 wt% aqueous suspension) = 9.8) was used. A coating layer slurry was produced in the same manner as in Example 1, except for this.

[0131] <Example 6> In Example 1, as the plate-like silicate-based composition, laponite containing 73.2 wt% SiO2, 13.7 wt% MgO, 0.8 wt% Li2O, 2.8 wt% Na2O (density: 1000 kg / m 3 , specific surface area: 370 m 2 / g, pH (on a 2 wt% aqueous suspension) = 9.8) was used. A coating layer slurry was produced in the same manner as in Example 1, except for this.

[0132] <Example 7> In Example 1, as the plate-like silicate-based composition, laponite containing 45.8 wt% SiO2, 41.2 wt% MgO, 0.8 wt% Li2O, 2.8 wt% Na2O (density: 1000 kg / m 3 , specific surface area: 370 m 2 / g, pH (on a 2 wt% aqueous suspension) = 9.8) was used. A coating layer slurry was produced in the same manner as in Example 1, except for this.

[0133] <Comparative Example 1> A mixture (solid content 20% by weight) was prepared by dispersing inorganic particles (Al2O3, particle size: 430 nm) and a dispersant (polyacrylic acid-based dispersant, Lubrizol, CK-7058) in water. Subsequently, styrene-butyl acrylate (styrene-butyl acrylate) with a particle size of 350 nm (glass transition temperature 40°C, sphericity 0.95, density 1.5 g / cm³) was added to the mixture as a polymer binder particle. 3 An inorganic emulsion was prepared by adding a surfactant (BYK, BYK-346) and stirring at a speed of 800 rpm to 1000 rpm for 10 minutes. The inorganic emulsion prepared contained 24% by weight of inorganic particles, 1.4% by weight of the dispersant, 17% by weight of the polymer binder particles, 0.1% by weight of the surfactant, and 57.5% by weight of water.

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

[0135] The coating layer slurries for Examples 1-3 and Comparative Example 1 were applied to both sides of the porous polymer substrate using a doctor blade in a bar coating method, and dried with a heat gun at 50°C to form a 3 μm thick coating layer on each side, thereby producing a separation film with a total thickness of 15 μm.

[0136] <Manufacturing of electrochemical elements> 1) Manufacturing of the positive electrode Cathode active material (LiNi 0.8 Mn 0.1 CO 0.1A slurry for the positive electrode active material layer was prepared by mixing O2, a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical Co.), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and removing the water to obtain a slurry of the remaining components at a concentration of 50 wt%. Next, the slurry was applied to the surface of an aluminum thin film (thickness 10 μm) and dried to produce a positive electrode having a positive electrode active material layer (thickness 120 μm).

[0137] 2) Manufacturing of the negative electrode A slurry for the negative electrode active material layer was prepared by mixing graphite (a blend of natural and artificial graphite), a conductive material (carbon black), a dispersant (polyvinylpyrrolidone, manufactured by Junsei Corporation), and a binder resin (a mixture of PVDF-HFP and PVDF) with water in a weight ratio of 97.5:0.7:0.14:1.66, and then removing the water to obtain a slurry of the remaining components at a concentration of 50 wt%. Next, the slurry was applied to the surface of a copper thin film (10 μm thick) and dried to produce a negative electrode having a negative electrode active material layer (120 μm thick).

[0138] 3) Lamination process The separation film of the example was interposed between the manufactured negative electrode and positive electrode and laminated, and an electrochemical element was obtained by performing a lamination process. The lamination process was carried out using a hot press at 70°C and 5.2 MPa for 10 seconds.

[0139] <Experimental Example 1: Confirmation of whether or not phase separation occurs> The coating layer slurries of Examples 1 to 7 and Comparative Example 1 were placed in 250 ml containers at room temperature (20°C to 25°C), and the containers were placed on a level surface. The presence or absence of phase separation (layer separation) was checked over time and summarized in Table 1 below.

[0140] <Experimental Example 2: Measurement of Dielectric Breakdown Voltage> For the separation membranes having a coating layer formed in Examples 1 to 7 and Comparative Example 1, which have a thickness of 12 μm, a pressure of 8 MPa at 70°C was applied, and the voltage was measured at 0.5 mA and over 3 seconds while the pressure was increased at a rate of 100 mV / s. The results are summarized in Table 1 below.

[0141] <Experimental Example 3: Measurement of Thermal Shrinkage Rate> Separation membranes produced from the slurries of Examples 1 to 7 and Comparative Example 1 were prepared as test specimens measuring 5 cm x 5 cm. After storage at 150°C for 30 minutes, the mechanical direction (MD) and transverse direction (TD) of each test specimen were measured, and the thermal shrinkage rate was calculated using the following formula 1, which is summarized in Table 1 below.

[0142]

number

[0143] <Experimental Example 5: Measurement of Peel Strength> Separation membranes produced from the slurries of Examples 1-7 and Comparative Example 1 were prepared as test specimens measuring 1.5 cm x 7 cm. After attaching the coating layer and a slide glass to the test specimen, the specimen was measured by applying force at a rate of 300 mm / min and pulling it at 180° using a UTM instrument (LLOYD Instrument LF Plus).

[0144] [Table 1] Referring to Table 1 above, it was confirmed that in Examples 1 to 7, which included the plate-type silicate composition, no phase separation occurred in the slurry even after being left standing for a period of time after the slurry was manufactured. In contrast, it was confirmed that in Comparative Example 1, which did not include the plate-type silicate composition, phase separation occurred in the slurry after being left standing for 3 days.

[0145] Furthermore, it was confirmed that Examples 1 to 7, which include the plate-type silicate composition, exhibit dielectric breakdown voltage, air permeability, and peel strength similar to those of Comparative Example 1, even when containing the plate-type silicate composition.

[0146] Furthermore, in Examples 1 to 7, the inclusion of the plate-type silicate composition in the slurry increased the internal cohesion within the coating layer, resulting in increased peel strength. In contrast, Comparative Example 1, which did not contain the plate-type silicate composition in the slurry, showed a decrease in peel strength.

[0147] The separation membrane for electrochemical elements according to one embodiment of the present invention, by including a plate-type silicate composition in the coating layer, can prevent phase separation of the slurry while maintaining the physical properties of conventional separation membranes, thereby improving storage safety and improving the peel strength of the coating layer. [Explanation of Symbols]

[0148] 100: Separation membrane for electrochemical elements 110: Porous polymer base material 130: Coating layer 300: Positive electrode 500: Negative electrode 1000: Electrochemical elements

Claims

1. Porous polymer substrate and The porous polymer substrate is provided with a coating layer comprising a plate-type silicate composition, polymer binder particles, and inorganic particles on at least one surface, The plate-shaped silicate composition is SiO ２ , MgO, Li ２ O, Na ２ A separation membrane for an electrochemical device, comprising O and one selected from the group consisting of combinations thereof.

2. The plate-shaped silicate composition is the SiO ２ A separation membrane for an electrochemical element according to claim 1, comprising 50% by weight or more and 60% by weight or less of the above.

3. The plate-shaped silicate composition contains 22% by weight or more and 28% by weight or less of the MgO, wherein the separation membrane for an electrochemical element is as described in claim 1.

4. The plate-shaped silicate composition, the Li ２ A separation membrane for an electrochemical element according to claim 1, comprising 0.5% by weight or more and 2.0% by weight or less of oxygen.

5. The aforementioned plate-shaped silicate composition, Na ２ A separation membrane for an electrochemical element according to claim 1, comprising 2.0% by weight or more and 8.0% by weight or less of oxygen.

6. In the aforementioned plate-type silicate composition, The SiO ２ It is included in an amount of 65% to 80% by weight. The aforementioned MgO is contained in an amount of 10% by weight or more and 20% by weight or less. The Li ２ O is present in an amount of 0.5% to 2.0% by weight. The Na ２ O is contained at 9% by weight or more and 20% by weight or less, and the separation membrane for an electrochemical element according to claim 1.

7. In the aforementioned plate-type silicate composition, The SiO ２ It is included in an amount of 70% to 75% by weight. The aforementioned MgO is contained in an amount of 13% by weight or more and 18% by weight or less. The Li ２ O is present in an amount of 1.0% to 1.5% by weight. The Na ２ The separation membrane for an electrochemical element according to claim 1, wherein O is contained in an amount of 12.0% by weight or more and 18.0% by weight or less.

8. In the aforementioned plate-type silicate composition, The SiO ２ It is included in an amount of 71% to 74% by weight. The aforementioned MgO is contained in an amount of 13% by weight or more and 16% by weight or less. The Li ２ O is present in an amount of 1.1% to 1.4% by weight. The Na ２ The separation membrane for an electrochemical element according to claim 1, wherein O is contained in an amount of 14.0% by weight or more and 16.0% by weight or less.

9. The content of the plate-shaped silicate composition is 0.1 parts by weight or more and 1.0 part by weight or less per 100 parts by weight of the coating layer, wherein the separation membrane for an electrochemical element according to claim 1.

10. The specific surface area of ​​the plate-type silicate composition is 250 m². ２ / g or more 400m ２ A separation membrane for an electrochemical element according to claim 1, wherein the amount is less than or equal to / g.

11. The density of the plate-type silicate composition is 900 kg / m³. ３ ~1050 kg / m ３ The separation membrane for an electrochemical element according to claim 1.

12. The separation membrane for an electrochemical element according to claim 1, wherein the pH of an aqueous suspension containing the plate-type silicate composition in an amount of 1% by weight or more and 3% by weight or less is 8.0 or more and 12.0 or less.

13. The aforementioned plate-shaped silicate composition, P ２ O ５ The separation membrane for an electrochemical element according to claim 1, further comprising one selected from the group consisting of F and combinations thereof.

14. The separation membrane for an electrochemical element according to claim 1, wherein the plate-shaped silicate composition is laponite.

15. An electrochemical element comprising a positive electrode, a negative electrode, and a separation membrane for an electrochemical element according to any one of claims 1 to 14, interposed between the positive electrode and the negative electrode.

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