Separation membrane for electrochemical elements having a polymer binder layer, electrochemical element containing the same, and method for manufacturing the same.

Abstract

The separation membrane for the electrochemical element comprises 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, wherein the first polymer binder is in solution form, and the content of the first polymer binder in the portion of the coating layer adjacent to the porous polymer substrate is greater than the content of the first polymer binder in the other portion separated from and facing the porous polymer substrate.

Description

[Technical Field]

[0001] This invention claims the benefit as of the filing date of Korean Patent Application No. 10-2023-0068198, filed with the Korean Intellectual Property Office on May 26, 2023, and all of its contents are included in this invention. This invention relates to a separation membrane for an electrochemical element, an electrochemical element containing the same, and a method for manufacturing the same, and further relates to electrodes, separation membranes, and secondary batteries manufactured using the same. [Background technology]

[0002] Among the components of an electrochemical element, the separation membrane includes a polymer substrate with a porous structure located between the positive and negative electrodes. Its roles are to isolate the positive and negative electrodes, prevent electrical short circuits between the two electrodes, and allow electrolytes and ions to pass through.

[0003] On the other hand, in order to improve the performance and safety of secondary batteries employing electrochemical elements, improvements have been made to the characteristics of the positive electrode, negative electrode, electrolyte, and separation membrane. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention provides a separation membrane for an electrochemical element, an electrochemical element containing the same, and a method for manufacturing the same, which improves the adhesion between the coating layer and the porous polymer substrate and improves the dispersibility of inorganic particles contained in the coating layer slurry, by arranging the polymer binder contained in the adhesive layer slurry at the interface between the coating layer and the porous polymer substrate.

[0005] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0006] According to an embodiment of the present invention, there is provided a separation membrane for an electrochemical device, comprising: 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. The first polymer binder is in solution form, and the content of the first polymer binder contained in a part of the coating layer adjacent to the porous polymer substrate is greater than the content of the first polymer binder contained in another part of the coating layer spaced apart from and facing the porous polymer substrate.

[0007] According to an embodiment of the present invention, the solubility of the second polymer binder in water is smaller than the solubility of the first polymer binder in water.

[0008] According to an embodiment of the present invention, the first polymer binder is selected from the group consisting of polyacrylic acid, polyurethane, polyacrylonitrile, polyethylene glycol, polyacrylamide, polyvinyl alcohol, and combinations thereof.

[0009] According to an embodiment of the present invention, the second polymer binder is in particle form.

[0010] An embodiment of the present invention provides a method for manufacturing the separation membrane for an electrochemical device, the method comprising: applying a slurry for a coating layer containing a first polymer binder and inorganic particles onto at least one surface of a porous polymer substrate to form a coating layer; and applying a slurry for an adhesive layer containing a first polymer binder and a second polymer binder onto the coating layer to form an adhesive layer. The first polymer binder is in solution form, and the solubility of the second polymer binder in water is smaller than the solubility of the first polymer binder in water.

[0011] According to an embodiment of the present invention, the method further comprises drying steps after the steps of forming the coating layer and the adhesive layer, respectively.

[0012] According to an embodiment of the present invention, the content of the first polymer binder dissolved in the solvent in the slurry for the coating layer is about 0.1 wt% or more and 10 wt% or less.

[0013] According to an embodiment of the present invention, the content of the second polymer binder dissolved in the solvent in the slurry for the adhesive layer is about 5 wt% or more and 40 wt% or less.

[0014] According to an embodiment of the present invention, the average particle size (D 90 ) of the particles contained in the slurry for the coating layer is about 0.01 μm or more and 10.0 μm or less.

[0015] An embodiment of the present invention provides an electrochemical element including a positive electrode; a negative electrode; and a separation membrane for the electrochemical element interposed between the positive electrode and the negative electrode, wherein the adhesive force between the porous polymer substrate and the coating layer is about 30 gf / 25 mm or more.

[0016] According to an embodiment of the present invention, the adhesive force between the porous polymer substrate and the coating layer is about 5 gf / 25 mm or more greater than the adhesive force between either one of the positive electrode or the negative electrode and the adhesive layer.

[0017] An embodiment of the present invention provides an electrochemical element including a positive electrode; a negative electrode; and a separation membrane interposed between the positive electrode and the negative electrode, the separation membrane including 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, wherein the second polymer binder is a solution type, and the adhesive force between the porous polymer substrate and the coating layer is greater than the adhesive force between either one of the positive electrode or the negative electrode and the adhesive layer.

Effect of the Invention

[0018] An electrochemical element separation membrane according to one embodiment of the present invention improves the adhesion between the coating layer and the porous polymer substrate.

[0019] A method for manufacturing an electrochemical element according to one embodiment of the present invention maintains a low viscosity of the slurry for the coating layer, thereby improving the dispersibility of inorganic particles and polymer binders.

[0020] An electrochemical element according to one embodiment of the present invention improves the adhesion between the coating layer and the porous polymer substrate, and improves the adhesion between the separation membrane and the electrode. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic diagram of a separation membrane for an electrochemical element according to one embodiment of the present invention. [Figure 2] This is a flowchart of a method for manufacturing a separation membrane for an electrochemical element according to one embodiment of the present invention. [Figure 3] This is a schematic diagram of an electrochemical element according to one embodiment of the present invention. [Modes for carrying out the invention]

[0022] In some of the attached drawings, corresponding components are given the same reference numerals. Those skilled in the art will understand that these drawings illustrate elements simply and clearly, and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements shown in the drawings may be exaggerated compared to others. Also, elements of known technology that are useful or essential in commercially viable embodiments may often be omitted so as not to detract from the spirit of the various embodiments of the present invention.

[0023] 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.

[0024] The terms used herein are for illustrative purposes only and are not intended to limit the invention; singular terms herein also include plural terms unless otherwise specified.

[0025] In this specification, "A and / or B" means "A and B, or A or B".

[0026] 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.

[0027] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0028] As used herein, “about,” “approximately,” and “substantially” are used to mean within or near the range of numerical values ​​or degrees, taking into account inherent manufacturing and material tolerances, and are used to prevent infringers from unfairly exploiting the content of disclosures that refer to precise or absolute numerical values ​​provided to aid in understanding the invention.

[0029] 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.

[0030] In this specification, the separation membrane has porous properties including numerous pores and acts 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.

[0031] While 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.

[0032] Therefore, in order to enhance the physical properties of the separation membrane, a coating layer is added to a porous polymer substrate. As one example of various methods for changing the physical properties of the coating layer by adding various substances to the coating layer, inorganic substances are added to the coating layer to improve the mechanical strength of the separation membrane, or inorganic substances or hydrates are added to the coating layer to improve the flame retardancy and heat resistance of the polymer substrate.

[0033] The separation membrane can be bonded to the electrode through a lamination process, and a polymer binder is added to the coating layer composition of the separation membrane to ensure adhesion between the electrode and the separation membrane.

[0034] On the other hand, when electrodes and a separation membrane are bonded together in the battery manufacturing process, battery manufacturing becomes easier, the battery thickness is uniformly realized, and the stiffness of the battery is improved. Therefore, multilayer separation membrane technology has been developed in which a first coating layer and a second coating layer are formed on the separation membrane. The adhesive strength between the electrode and the separation membrane is affected by the adhesion between the adhesive binder and the electrode, the adhesion between the adhesive binder and the inorganic coating layer, and the adhesion between the inorganic coating layer and the porous substrate. When the solvent used for the first coating layer and the second coating layer is the same in the manufacturing process of the multilayer separation membrane, there is a problem that the adhesive strength between the first coating layer and the porous polymer substrate weakens during the manufacturing process of the second coating layer. To solve this problem, a solution-type binder is added to the slurry for manufacturing the first coating layer to improve the adhesive strength between the porous polymer substrate and the first coating layer. However, the slurry for manufacturing the first coating layer has the problem that its viscosity increases due to the solution-type binder, reducing its dispersibility.

[0035] In order to prevent such problems, the present invention provides a separation membrane that can improve the adhesion between a porous polymer substrate and a coating layer, while simultaneously preventing a decrease in the dispersibility of inorganic substances contained in the coating layer.

[0036] The present invention will be described in more detail below.

[0037] Figure 1 is a schematic diagram of a separation membrane 100 for an electrochemical element according to one embodiment of the present invention. The separation membrane 100 for an electrochemical element, which is one embodiment of the present invention, will be described with reference to Figure 1.

[0038] One embodiment of the present invention provides a separation membrane 100 for an electrochemical element, comprising: a porous polymer substrate 110; a coating layer 130 provided on at least one surface of the porous polymer substrate 110 and containing a first polymer binder 131 and inorganic particles 133; and an adhesive layer 150 provided on the coating layer 130 and containing a second polymer binder 151, wherein the first polymer binder 131 is in solution form, and the content of the first polymer binder 131 in a portion of the coating layer 130 adjacent to the porous polymer substrate 110 is greater than the content of the first polymer binder 131 in another portion separated from and facing the porous polymer substrate 110.

[0039] An electrochemical element separation membrane 100 according to one embodiment of the present invention improves the adhesion between the coating layer 130 and the porous polymer substrate 110.

[0040] 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 are allowed to pass through while blocking electrical contact, thereby realizing a shutdown function at an appropriate temperature.

[0041] According to one embodiment of the present invention, the porous polymer substrate 110 is manufactured using a polyolefin resin as the base resin. Examples of polyolefin resins include polyethylene, polypropylene, and polypentene, and the substrate may contain one or more of these. The porous separation membrane, i.e., having a large number of pores, manufactured using the polyolefin resin as the base resin, provides a shutdown function at an appropriate temperature.

[0042] According to one embodiment of the present invention, the weight-average molecular weight of the polyolefin resin is approximately 500,000 to 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 is 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 is calculated by adding up the weight-average molecular weights according to the content ratio of each polyolefin resin.

[0043] In this specification, "weight-average molecular weight (Mw)" is measured by gel permeation chromatography (GPC, PL GPC220, Agilent Technologies), and the measurement conditions are as follows.

[0044] - 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)

[0045] According to one embodiment of the present invention, the porous polymer substrate 110 is 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 comprises 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.

[0046] According to one embodiment of the present invention, the average pore size and maximum pore size of the separation membrane 100 can be easily manufactured by a person skilled in the art to conform to the scope of the present invention by adjusting the mixing ratio of the plasticizer, the stretching ratio, and the heat-fixing treatment temperature.

[0047] According to one embodiment of the present invention, the separation membrane 100 for the electrochemical element includes a coating layer 130 provided on at least one surface of the porous polymer substrate 110. As described above, by including the coating layer 130 provided on at least one surface of the porous polymer substrate 110 in the separation membrane 100 for the electrochemical element, the heat resistance of the separation membrane is improved, the mechanical properties are improved, and electrical short circuits of the electrodes due to shrinkage of the separation membrane at high temperatures are prevented.

[0048] According to one embodiment of the present invention, the coating layer 130 includes a first polymer binder 131 and inorganic particles 133. As described above, the inclusion of the first polymer binder 131 and the inorganic particles 133 in the coating layer 130 improves the heat resistance of the separation membrane, improves its mechanical properties, prevents electrical short circuits of the electrodes due to shrinkage of the separation membrane at high temperatures, forms pores inside the coating layer, and improves the adhesion between the porous polymer substrate and the coating layer.

[0049] In one embodiment of the present invention, the adhesive strength between the porous polymer substrate and the coating layer refers to the bonding strength between the porous polymer substrate and the coating layer. For example, the adhesive strength between the porous polymer substrate and the coating layer is measured by applying a separation membrane and adhesive tape to a universal testing machine (UTM) and then measuring the peel strength when peeling them off. Alternatively, a test piece of separation membrane, prepared by cutting it to 70 mm (length) x 25 mm (width), is attached to a glass plate using double-sided tape and fixed in place. The separation membrane portion of the test piece is then peeled off at a speed of 150 mm / min at 25°C at an angle of 180°, and the strength at this time is measured.

[0050] According to one embodiment of the present invention, the coating layer 130 includes a plurality of pores. For example, the coating layer 130 is a porous coating layer. Alternatively, the coating layer 130 is a porous coating layer containing a plurality of pores internally. As described above, the inclusion of a plurality of pores in the coating layer 130 allows lithium ions to pass through and current to flow while physically blocking contact between the negative electrode and the positive electrode.

[0051] According to one embodiment of the present invention, the coating layer 130 is formed by the binding and accumulation of inorganic particles 133 by a first polymer binder 131. The pores inside the coating layer 130 are due to interstitial volume, which is the empty space between the inorganic particles.

[0052] According to one embodiment of the present invention, the first polymer binder 131 is in solution form. For example, the first polymer binder 131 is dissolved in a solvent and provided in the pores of the coating layer. For example, the first polymer binder 131 is dissolved in a solvent contained in the coating layer slurry and / or adhesive layer slurry described later and provided in the pores of the coating layer. As described above, by selecting the first polymer binder 131 to be in solution form, the adhesion between the porous polymer substrate and the coating layer is improved.

[0053] In one embodiment of the present invention, "solution type" means a substance that dissolves in 100 g of solvent at room temperature (20°C) and 1 atmosphere at a concentration of 50% by weight or more relative to 100% by weight of the substance to be dissolved.

[0054] According to one embodiment of the present invention, the thickness of the coating layer 130 is formed to a thickness of about 1 μm to 20 μm on either of the porous polymer substrates 110, but is not particularly limited thereto. The thickness can be adjusted to an appropriate range by those skilled in the art from the standpoint of heat resistance and electrical resistance.

[0055] In one embodiment of the present invention, the thickness of the porous polymer substrate, the coating layer, and / or the adhesive layer described later is measured using a contact-type thickness gauge. For example, the VL-50S-B from Mitutoyo is used as the contact-type thickness gauge.

[0056] According to one embodiment of the present invention, the adhesive layer 150 is provided on the coating layer 130. As described above, by providing the adhesive layer 150 on the coating layer 130, the adhesive strength between the electrode and the separation membrane is improved, and at the same time, the heat resistance of the separation membrane is improved.

[0057] According to one embodiment of the present invention, the adhesive layer 150 contains a second polymer binder 151. As described above, by including the second polymer binder 151 in the adhesive layer 150, the uniformity of the inorganic particles in the coating layer is improved, increasing the uniformity of the thickness of the separation film, and improving the adhesion of the separation film to the electrode.

[0058] According to one embodiment of the present invention, the amount of the first polymer binder 131 contained in a portion of the coating layer 130 adjacent to the porous polymer substrate 110 is greater than the amount of the first polymer binder 131 contained in another portion that is separated from and opposite the porous polymer substrate 110. As described above, by making the amount of the first polymer binder 131 contained in a portion of the coating layer 130 adjacent to the porous polymer substrate 110 greater than the amount of the first polymer binder 131 contained in another portion that is separated from and opposite the porous polymer substrate 110, the first polymer binder 131 is excessively distributed in the portion of the coating layer 130 adjacent to the porous polymer substrate 110, thereby improving the adhesion between the coating layer 130 and the porous polymer substrate 110. Furthermore, by relatively reducing the content of the first polymer binder 131 in the coating layer slurry described later, it is possible to suppress the increase in viscosity of the coating layer slurry and realize a lower particle size, thereby improving the dispersibility of the inorganic particles 133 within the coating layer slurry.

[0059] According to one embodiment of the present invention, the solubility of the second polymer binder 151 in water is less than that of the first polymer binder 131 in water. As described above, by making the solubility of the second polymer binder 151 in water less than that of the first polymer binder 131 in water, the second polymer binder (151) does not dissolve in the solvent of the adhesive layer slurry, and the second polymer binder 151 remains in the adhesive layer 150, improving the adhesion strength of the adhesive layer 150 to the electrode.

[0060] According to one embodiment of the present invention, the first polymer binder 131 is one selected from the group consisting of polyacrylic acid, polyurethane, polyacrylonitrile, polyethylene glycol, polyacrylamide, polyvinyl alcohol, and combinations thereof. As described above, by selecting the first polymer binder 131 to be one selected from the group consisting of polyacrylic acid, polyurethane, polyacrylonitrile, polyethylene glycol, polyacrylamide, polyvinyl alcohol, and combinations thereof, the binding force of the inorganic particles 133 within the coating layer 130 is improved, and the adhesion between the coating layer and the porous polymer substrate 110 is improved.

[0061] According to one embodiment of the present invention, the second polymer binder 151 is in solution form. For example, the second polymer binder 151 is dissolved in a solvent and provided in the pores of the coating layer 131 and / or the porous polymer substrate 110.

[0062] Alternatively, the second polymer binder 151 is dissolved in a solvent contained in the slurry for the adhesive layer, as described later, and provided in the pores of the coating layer 130 and / or the porous polymer substrate 110. As described above, by selecting the second polymer binder 151 to be in solution form, the first polymer binder 131 improves the adhesion between the porous polymer substrate 110 and the coating layer (130), while selecting either a solution form or a particle form.

[0063] According to one embodiment of the present invention, the second polymer binder 151 is in the form of particles. As described above, by selecting the second polymer binder 151 to be in the form of particles, the uniformity of the inorganic particles in the coating layer is improved, and the adhesion between the separation membrane and the electrode is improved.

[0064] According to one embodiment of the present invention, the second polymer binder 151 is an acrylic binder, a polyvinylidene binder, or a combination thereof. By selecting the second polymer binder from the above, the adhesion between the electrodes and the separation membrane can be improved in the battery lamination process, making it possible to easily manufacture batteries and stably implement the stacking process.

[0065] According to one embodiment of the present invention, the acrylic binder is a polymer containing a carboxylic acid ester as a repeating unit, for example, a (meth)acrylic acid ester or an acrylic-styrene copolymer.

[0066] According to one embodiment of the present invention, examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-amyl (meth)acrylate, i-amyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, and (meth)acrylate. Examples include decyl acrylate, hydroxymethyl (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, allyl (meth)acrylate, ethylene di(meth)acrylate, and one or more selected from these. Of these, one or more may be selected from methyl (meth)acrylate, ethyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, or it may be methyl (meth)acrylate.

[0067] According to one embodiment of the present invention, the acrylic-styrene copolymer comprises an acrylic binder, the acrylic binder being polyacrylate-based. For example, the acrylic binder is one or more selected from the group consisting of styrene-butadiene rubber, nitril-butadiene rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, and acrylate polymers, and more specifically, it is a copolymer containing acrylate.

[0068] According to one embodiment of the present invention, the polyvinylidene-based binder is a copolymer of polyvinylidene fluoride (PVdF) and hexafluoropropylene (HFP). As described above, by selecting a polyvinylidene-based binder, the porosity of the separation membrane can be maintained, and the adhesive strength can be maintained even if the coating layer is wetted by the electrolyte after the battery is activated. Furthermore, the stiffness of the battery can be improved, and bending of the separation membrane can be prevented.

[0069] According to one embodiment of the present invention, the polyvinylidene binder is a polyvinylidene binder having a hexafluoropropylene (HFP) content of about 1% to 50% by weight. For example, the hexafluoropropylene (HFP) content in the polyvinylidene binder is about 1% to 50% by weight, about 2% to 45% by weight, about 3% to 40% by weight, about 4% to 35% by weight, about 5% to 30% by weight, about 7% to 25% by weight, or about 10% to 20% by weight. As described above, by selecting a polyvinylidene binder having a hexafluoropropylene content of about 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 one embodiment of the present invention, the degree of substitution of the polyvinylidene-based binder refers to the weight ratio containing hexafluoropropylene.

[0070] According to one embodiment of the present invention, the content of the first polymer binder 131 in the coating layer is about 25 parts by weight or less per 100 parts by weight of the coating layer 130. For example, the total content of the first polymer binder 131 is about 0 parts by weight and 25 parts by weight or less, about 1 part by weight or more and 24 parts by weight or less, about 2 parts by weight or more and 23 parts by weight or less, about 3 parts by weight or more and 22 parts by weight or less, about 4 parts by weight or more and 21 parts by weight or less, about 5 parts by weight or more and 20 parts by weight or less, about 6 parts by weight or more and 19 parts by weight or less, about 7 parts by weight or more and 18 parts by weight or less, about 8 parts by weight or more and 17 parts by weight or less, about 9 parts by weight or more and 16 parts by weight or less, about 10 parts by weight or more and 15 parts by weight or less, about 11 parts by weight or more and 14 parts by weight or less, or about 12 parts by weight or more and 13 parts by weight or less per 100 parts by weight of the coating layer 130. By adjusting the content of the first polymer binder 131 within the range described above, the ease of assembly in the electrode assembly process is improved.

[0071] According to one embodiment of the present invention, the content of the inorganic particles 133 is about 75 parts by weight more than 100 parts by weight of the coating layer 130. For example, the content of the inorganic particles 133 is about 75 parts by weight more than 100 parts by weight, about 76 parts by weight or more and 99 parts by weight or less, about 77 parts by weight or more and 98 parts by weight or less, about 78 parts by weight or more and 97 parts by weight or less, about 79 parts by weight or more and 96 parts by weight or less, about 80 parts by weight or more and 95 parts by weight or less, about 81 parts by weight or more and 94 parts by weight or less, about 82 parts by weight or more and 93 parts by weight or less, about 83 parts by weight or more and 92 parts by weight or less, about 84 parts by weight or more and 91 parts by weight or less, about 85 parts by weight or more and 90 parts by weight or less, about 86 parts by weight or more and 89 parts by weight or less, or about 87 parts by weight or more and 88 parts by weight or less, relative to 100 parts by weight of the coating layer 130. By adjusting the content of the inorganic particles 133 within the range described above, the heat resistance of the separation membrane is improved.

[0072] According to one embodiment of the present invention, the inorganic particles 133 that can be used in the coating layer 130 are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles that can be used in one embodiment of the present invention are within the operating voltage range of the electrochemical element to which they are applied (for example, Li / Li + There are no particular restrictions as long as oxidation and / or reduction reactions do not occur at approximately 0V to 5V (based on the reference voltage).

[0073] According to one embodiment of the present invention, non-limiting examples of the inorganic particles 133 include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT, 0 <x<1、0<y<1)、Pb(Mg 1 / 3 Nb 2 / 3)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 oxides (Zn2SnO4, ZnSnO3), antimony trioxide (Sb2O3), antimony tetroxide (Sb2O4), antimony pentoxide (Sb2O5), etc. are present, and one or more of these are included.

[0074] According to one embodiment of the present invention, the average diameter (D 50 ) of the inorganic particles 133 is not particularly limited, but is preferably in the range of about 0.3 μm or more and 1 μm or less for the formation of a coating layer 130 having a uniform thickness and an appropriate porosity. For example, when it is less than about 0.3 μm, the dispersibility of the inorganic particles in the slurry prepared for manufacturing the coating layer decreases, and when it exceeds about 1 μm, the surface of the formed coating layer becomes non-uniform or the thickness of the coating layer increases.

[0075] In one embodiment of the present invention, "D 50 particle size" means the particle size at the 50% point of the cumulative distribution of the number of particles according to the particle size. The particle size is measured using the laser diffraction method. For example, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), and when the particles pass through the laser beam, the difference in the diffraction pattern according to the particle size is measured to calculate the particle size distribution. By calculating the particle diameter at the point where the cumulative distribution of the number of particles according to the particle size in the measuring device reaches 50%, D 50 particle size is measured.

[0076] According to one embodiment of the present invention, the porosity of the coating layer 130 may be about 30 volume% or more. For example, the porosity of the coating layer 130 may be about 30 volume% to 70 volume%, about 32 volume% to 68 volume%, about 34 volume% to 66 volume%, about 36 volume% to 64 volume%, about 38 volume% to 62 volume%, about 40 volume% to 60 volume%, about 42 volume% to 58 volume%, about 44 volume% to 56 volume%, about 46 volume% to 54 volume%, or about 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. For example, if the porosity is about 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 approximately 30% by volume or more is advantageous from the viewpoint of ion permeability.

[0077] In one embodiment of the present invention, "porosity" refers to the ratio of the volume occupied by pores to the total volume, and is used as the unit of volume %. It can be used interchangeably with terms such as void ratio and porosity.

[0078] In one embodiment of the present invention, the "porosity" corresponds to the subtraction value obtained by subtracting the volume of each component of the coating layer 130 converted to weight and density from the volume calculated in terms of thickness, width, and length of the coating layer 130.

[0079] In one embodiment of the present invention, the porosity and pore size of the coating layer 130 are measured by the BET 6-point method using nitrogen gas adsorption flow method with scanning electron microscope (SEM) images, a mercury porosimeter, a capillary flow porometer, or a porosimetry analyzer (Bell Japan Inc, Belsorp-II mini). In this case, it is advantageous to use a capillary flow porometer.

[0080] One embodiment of the present invention provides a method for manufacturing the separation membrane 100 for an electrochemical element, comprising the steps of: applying a coating layer slurry containing a first polymer binder 131 and inorganic particles 133 to at least one surface of a porous polymer substrate 110 to form a coating layer 130 (S10); and applying an adhesive layer slurry containing a first polymer binder 131 and a second polymer binder 151 onto the coating layer 130 to form an adhesive layer 150 (S30).

[0081] A method for manufacturing a separation membrane 100 for an electrochemical element according to one embodiment of the present invention maintains a low viscosity of the slurry for the coating layer and improves the dispersibility of inorganic particles and polymer binders.

[0082] Figure 2 is a flowchart of the method for manufacturing the separation membrane 100 for an electrochemical element according to one embodiment of the present invention. The method for manufacturing the separation membrane 100 for an electrochemical element according to one embodiment of the present invention will be explained with reference to Figure 2. In the explanation of the method for manufacturing the separation membrane 100 for an electrochemical element according to one embodiment of the present invention, content that overlaps with the explanation of the separation membrane for an electrochemical element described above will be omitted.

[0083] According to one embodiment of the present invention, the step of preparing a slurry for the coating layer containing a first polymer binder 131 and inorganic particles 133 is performed before the step of providing the coating layer 130 (S20). As described above, in the step of preparing the slurry for the coating layer (S10), the viscosity of the slurry for the coating layer can be made low, thereby improving the dispersibility of the inorganic particles in the slurry and improving the uniformity of the coating layer.

[0084] According to one embodiment of the present invention, the process includes a step (S20) of applying a coating layer slurry containing a first polymer binder 131 and inorganic particles 133 to at least one surface of a porous polymer substrate 110 to form a coating layer 130. As described above, by including the step (S20) of applying a coating layer slurry containing a first polymer binder 131 and inorganic particles 133 to at least one surface of a porous polymer substrate 110 to form a coating layer 130, the coating layer 130 can be formed in a single application, and the inorganic particles are uniformly dispersed in the coating layer slurry, improving the uniformity of the coating layer.

[0085] According to one embodiment of the present invention, the step of preparing an adhesive layer slurry containing a first polymer binder 131 and a second polymer binder 151 is included before the step of providing the adhesive layer 150 (S50) (S40). As described above, by including the step of preparing an adhesive layer slurry containing a first polymer binder 131 and a second polymer binder 151 (S40) before the step of providing the adhesive layer 150 (S50), the first polymer binder can be included in the coating layer slurry at a low content (10% by weight or less), the viscosity of the coating layer slurry can be reduced, and the dispersibility of the inorganic particles in the coating layer slurry can be improved.

[0086] According to one embodiment of the present invention, the process includes the step (S50) of applying an adhesive layer slurry containing a first polymer binder 131 and a second polymer binder 151 onto the coating layer 130 to form an adhesive layer 150. The adhesive layer 150 can be formed in a single application, and the first polymer binder, which is a liquid dissolved in the adhesive layer slurry, moves into the pores of the coating layer, thereby embodying the first polymer binder in excess on the porous polymer substrate.

[0087] 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, and / or the method for applying the adhesive layer slurry to the surface of the coating layer 130, is not limited to either one method, and conventional methods known in the art can be used. For example, various methods such as dip coating, die coating, roll coating, comma coating, gravure, or mixtures thereof can be used.

[0088] According to one embodiment of the present invention, the process further includes drying steps (S30, S60) after the step of providing the coating layer 130 (S20) and the step of providing the adhesive layer 150 (S50). As described above, by further including drying steps (S30, S60) after the step of providing the coating layer 130 (S20) and the step of providing the adhesive layer 150 (S50), damage to the coating layer can be minimized and the solvent contained in the slurry can be easily removed.

[0089] On the other hand, the procedure for manufacturing the electrochemical element separation film 100 described above can be appropriately modified and carried out. For example, the preparation step for the adhesive layer slurry (S40) can be carried out in the same way as the preparation step for the coating layer slurry (S10).

[0090] According to one embodiment of the present invention, the drying step is performed by appropriately setting time conditions to minimize the occurrence of surface defects in the coating layer 130 and / or the adhesive layer 150. The drying can be performed using drying aids such as a drying oven or hot air within an appropriate range.

[0091] According to one embodiment of the present invention, the first polymer binder 131 and the inorganic particles 133 are dissolved and dispersed in a solvent to produce a slurry for a coating layer. The solvent is preferably one that has a similar solubility index to the binder polymer to be used and a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of usable solvents include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. For example, the solvent is water. The content ratio of the inorganic particles to the polymer binder particles is as described later and is appropriately adjusted considering the thickness, pore size, and porosity of the coating layer ultimately produced according to one embodiment of the present invention.

[0092] According to one embodiment of the present invention, a polymer binder resin, i.e., a first polymer binder particle 131 and a second polymer binder 151, is dispersed and dissolved in a suitable solvent to provide a slurry for the adhesive layer. The solvent is preferably one that has a solubility index similar to that of the binder polymer to be used and has a low boiling point. This is to facilitate uniform mixing and subsequent solvent removal. Non-limiting examples of usable solvents include acetone, tetrahydrofuran, methylene chloride, chloroform, dimethylformamide, N-methyl-2-pyrrolidone (NMP), cyclohexane, water, or mixtures thereof. Alternatively, the solvent may be water.

[0093] According to one embodiment of the present invention, the content of the first polymer binder 131 dissolved in the solvent in the coating layer slurry is about 0.1% by weight or more and 10% by weight or less. For example, the content of the first polymer binder 131 dissolved in the solvent in the coating layer slurry is about 0.2% by weight or more and 9.9% by weight or less, about 0.3% by weight or more and 9.8% by weight or less, about 0.4% by weight or more and 9.7% by weight or less, about 0.5% by weight or more and 9.6% by weight or less, about 0.6% by weight or more and 9.5% by weight or less, about 0.7% by weight or more and 9.4% by weight or less, about 0.8% by weight or more and 9.3% by weight or less, about 0.9% by weight or more and 9.2% by weight or less, about 1.0% by weight or more and 9.1% by weight or less, about 1.1% to 9.0% by weight, approximately 1.2% to 8.9% by weight, approximately 1.3% to 8.8% by weight, approximately 1.4% to 8.7% by weight, approximately 1.5% to 8.6% by weight, approximately 1.6% to 8.5% by weight , about 1.7% to 8.4% by weight, about 1.8% to 8.3% by weight, about 1.9% to 8.2% by weight, about 2.0% to 8.1% by weight, about 2.1% to 8.0% by weight, about 2.2% to 7.9% by weight About 2.3% to 7.8% by weight, about 2.4% to 7.7% by weight, about 2.5% to 7.6% by weight, about 2.6% to 7.5% by weight, about 2.7% to 7.4% by weight, about 2.8% to 7.3 Weight% or less, approximately 2.9% to 7.2% by weight, approximately 3.0% to 7.1% by weight, approximately 3.1% to 7.0% by weight, approximately 3.2% to 6.9% by weight, approximately 3.3% to 6.8% by weight, approximately 3.4% by weight to 6 It is 0.7% by weight or less, approximately 3.5% by weight or more and 6.6% by weight or less, approximately 3.6% by weight or more and 6.5% by weight or less, approximately 3.7% by weight or more and 6.4% by weight or less, approximately 3.8% by weight or more and 6.3% by weight or less, approximately 3.9% by weight or more and 6.2% by weight or less, approximately 4.0% by weight or more and 6.1% by weight or less, approximately 4.1% by weight or more and 6.0% by weight or less, approximately 5.2% by weight or more and 5.9% by weight or less, approximately 5.3% by weight or more and 5.8% by weight or less, approximately 5.4% by weight or more and 5.7% by weight or less, or approximately 5.5% by weight or more and 5.6% by weight or less.Within the range described above, the binding strength of the coating layer is improved by adjusting the content of the first polymer binder 131 dissolved in the solvent in the slurry for the coating layer.

[0094] According to one embodiment of the present invention, the slurry for the coating layer further contains a dispersant. For example, the dispersant is sodium carboxymethylcellulose. As described above, the further inclusion of a dispersant in the slurry for the coating layer improves the degree of dispersion of inorganic particles contained in the slurry for the coating layer.

[0095] According to one embodiment of the present invention, the content of the dispersant is about 1% by weight or more and 5% by weight or less of the total content of the coating layer slurry excluding the solvent. By adjusting the content of the dispersant in the coating layer slurry within the above range, the degree of dispersion of inorganic particles contained in the coating layer slurry is improved.

[0096] According to one embodiment of the present invention, the content of the first polymer binder 131 dissolved in the solvent in the slurry for the adhesive layer is about 5% by weight or more and 40% by weight or less. For example, the content of the first polymer binder 131 dissolved in the solvent in the slurry for the adhesive layer is about 6% by weight or more and 39% by weight or less, about 7% by weight or more and 38% by weight or less, about 9% by weight or more and 37% by weight or less, about 10% by weight or more and 36% by weight or less, about 11% by weight or more and 35% by weight or less, about 12% by weight or more and 34% by weight or less, about 13% by weight or more and 32% by weight or less, about 14% by weight or more and 31% by weight or less, about 15% by weight or more and 30% by weight or less, about 16% by weight or more and 29% by weight or less, about 17% by weight or more and 28% by weight or less, about 19% by weight or more and 27% by weight or less, about 20% by weight or more and 26% by weight or less, about 21% by weight or more and 25% by weight or less, and about 22% by weight or more and 24% by weight or less. By adjusting the content of the first polymer binder 131 dissolved in the solvent in the slurry for the adhesive layer within the range described above, the adhesive strength between the porous polymer substrate and the coating layer is improved.

[0097] According to one embodiment of the present invention, the content of the second polymer binder 151 in the slurry for the adhesive layer is about 30% by weight or more and 95% by weight or less. For example, the content of the second polymer binder 151 in the slurry for the adhesive layer is about 35% by weight or more and 90% by weight or less, about 40% by weight or more and 85% by weight or less, about 45% by weight or more and 80% by weight or less, about 50% by weight or more and 75% by weight or less, about 55% by weight or more and 70% by weight or less, or about 60% by weight or more and 65% by weight or less. By adjusting the content of the second polymer binder 151 in the slurry for the adhesive layer within the above range, the adhesion between the electrode and the separation membrane is improved.

[0098] According to one embodiment of the present invention, the viscosity of the coating layer slurry may be about 20 cp to 40 cp. For example, the viscosity of the coating layer slurry may be about 21 cp to 39 cp, about 22 cp to 38 cp, about 23 cp to 37 cp, about 24 cp to 36 cp, about 25 cp to 35 cp, about 26 cp to 34 cp, about 27 cp to 33 cp, about 28 cp to 32 cp, or about 29 cp to 31 cp. By adjusting the viscosity of the coating layer slurry within the above range, the dispersibility of inorganic particles in the coating layer slurry can be improved, and the uniformity of the coating layer can be improved.

[0099] According to one embodiment of the present invention, the average particle size (D) of the particles contained in the slurry for the coating layer 90 The average particle size (D) of the particles contained in the coating layer slurry within the above range is approximately 0.01 μm to 10.0 μm. 90 By adjusting the above, the thickness of the coating layer can be reduced, and the dispersibility of the slurry for the coating layer is improved.

[0100] In one embodiment of the present invention, "D 90"Particle size" refers to the particle size at the 90% point of the cumulative distribution of particle numbers corresponding to the particle size. The particle size is measured using the laser diffraction method. For example, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac S3500), and the difference in diffraction patterns corresponding to the particle size is measured as the particles pass through the laser beam to calculate the particle size distribution. 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 90%, D 90 Measure the particle size.

[0101] According to one embodiment of the present invention, the separation membrane 100 is interposed between the negative electrode and the positive electrode and manufactured as an electrochemical element by a lamination process in which heat and / or pressure are applied to bond them together. In one embodiment of the present invention, the lamination process is carried out by a roll press apparatus including a pair of pressure rollers. That is, the negative electrode, the separation membrane, and the positive electrode are sequentially laminated and placed between the pressure rollers to achieve interlayer bonding. In this case, the lamination process is carried out by a hot pressurization method.

[0102] Figure 3 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 with reference to Figures 1 and 3.

[0103] 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 for the electrochemical element interposed between the positive electrode 300 and the negative electrode 500, wherein the adhesive strength between the porous polymer substrate 110 and the coating layer 130 is approximately 30 gf / 25 mm or more.

[0104] An electrochemical element 1000 according to one embodiment of the present invention improves the adhesion between the coating layer 130 and the porous polymer substrate 110, and improves the adhesion between the separation membrane 100 and the electrode.

[0105] According to one embodiment of the present invention, the electrochemical element 1000 includes a positive electrode 300; a negative electrode 500; and a separation membrane 100 for the electrochemical element interposed between the positive electrode 300 and the negative electrode 500. As described above, by including the positive electrode 300; the negative electrode 500; and the separation membrane 100 for the electrochemical element interposed between the positive electrode 300 and the negative electrode, the uniformity of the coating layer is improved and the adhesion between the coating layer and the porous polymer substrate is improved.

[0106] According to one embodiment of the present invention, the adhesive strength between the porous polymer substrate 110 and the coating layer 130 is approximately 30 gf / 25 mm or more. For example, the adhesive strength between the porous polymer substrate 110 and the coating layer 130 is approximately 30 gf / 25 mm to 100 gf / 25 mm, approximately 35 gf / 25 mm to 95 gf / 25 mm, approximately 40 gf / 25 mm to 90 gf / 25 mm, approximately 45 gf / 25 mm to 85 gf / 25 mm, approximately 50 gf / 25 mm to 80 gf / 25 mm, approximately 55 gf / 25 mm to 75 gf / 25 mm, or approximately 60 gf / 25 mm to 70 gf / 25 mm. Alternatively, the adhesive strength refers to the dry adhesive strength. By adjusting the adhesive strength between the porous polymer substrate 110 and the coating layer 130 within the range described above, the ease of assembly in the electrode assembly process is improved.

[0107] In one embodiment of the present invention, the "adhesion force" is measured by first bonding the electrode and the separation membrane at 60°C and 6.5MPa to create a half-cell, and then using a UTM device, applying force to the half-cell at 180°C and a measuring speed of 300 mm / min to measure the force required to separate the electrode and the separation membrane.

[0108] According to one embodiment of the present invention, the adhesive strength between the porous polymer substrate 110 and the coating layer 130 is approximately 5 gf / 25 mm or more greater than the adhesive strength between either the positive electrode 300 or the negative electrode 500 and the adhesive layer 150. For example, the adhesive strength between the porous polymer substrate 110 and the coating layer 130 is approximately 5 gf / 25 mm to 100 gf / 25 mm, approximately 10 gf / 25 mm to 95 gf / 25 mm, approximately 15 gf / 25 mm to 90 gf / 25 mm, and approximately 20 gf / 25 mm or more greater than the adhesive strength between either the positive electrode 300 or the negative electrode 500 and the adhesive layer 150. The adhesion strength between the porous polymer substrate 110 and the coating layer 130 is greater than or equal to 85gf / 25mm, approximately 25gf / 25mm to 80gf / 25mm, approximately 30gf / 25mm to 75gf / 25mm, approximately 35gf / 25mm to 70gf / 25mm, approximately 40gf / 25mm to 65gf / 25mm, approximately 45gf / 25mm to 60gf / 25mm, or approximately 50gf / 25mm to 55gf / 25mm. Within the above range, the adhesion strength between the porous polymer substrate 110 and the coating layer 130 is improved by adjusting the difference in adhesion strength between either the positive electrode 300 or the negative electrode 500 and the adhesive layer 150, thereby improving the adhesion strength between the separation membrane 100 and the electrode.

[0109] According to one embodiment of the present invention, the positive electrode 300 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 xNi-site type lithium nickel oxide represented by 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 oxide represented by 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 Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compound; contains one or more mixtures of Fe2(MoO4)3.

[0110] According to an embodiment of the present invention, the negative electrode 500 includes a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material, a conductive material, and a binder resin on at least one surface of the current collector. As the negative electrode active material, the negative electrode includes carbon such as lithium metal oxide, graphitized carbon, and graphite-based carbon; Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, Group 1, 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; contains one or more mixtures selected from titanium oxides.

[0111] According to one embodiment of the present invention, the conductive material is, for example, one selected from the group consisting of graphite, carbon black, carbon fibers or metal fibers, metal powder, conductive whiskers, conductive metal oxides, activated carbon, and polyphenylene derivatives, or a mixture of two or more conductive materials from this group. For example, it is 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 conductive materials from this group.

[0112] According to one embodiment of the present invention, the current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, for example, stainless steel, copper, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc. can be used.

[0113] According to one embodiment of the present invention, the binder resin is 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.

[0114] According to one embodiment of the present invention, the cathode slurry for producing the cathode active material layer contains a dispersant, and the dispersant is a pyrrolidone compound. Alternatively, the dispersant is N-methylpyrrolidone (ADC-01, LG Chemical Co., Ltd.).

[0115] According to one embodiment of the present invention, the amount of dispersant contained in the positive electrode slurry may be about 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the positive electrode slurry. For example, the amount of dispersant contained in the positive electrode slurry may be about 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the positive electrode slurry.

[0116] According to one embodiment of the present invention, the negative electrode slurry for producing the negative electrode active material layer may contain a dispersant, the dispersant being a polypyrrolidone compound. For example, the dispersant is polyvinylpyrrolidone (Junsei Corporation).

[0117] According to one embodiment of the present invention, the amount of dispersant contained in the negative electrode slurry is approximately 0 parts by weight and 0.5 parts by weight or less per 100 parts by weight of the negative electrode slurry. For example, the amount of dispersant contained in the negative electrode slurry is approximately 0.05 parts by weight and 0.4 parts by weight or less per 100 parts by weight of the negative electrode slurry.

[0118] According to one embodiment of the present invention, the electrochemical element prepared as described above is placed in a suitable case and an electrolyte is injected to manufacture a battery.

[0119] According to one embodiment of the present invention, the electrolyte is A + B - A salt with a structure like this, + is Li + kaNa + , K + It contains alkali metal cations such as, or ions consisting of combinations thereof, B - PF6 - BF4 - Cl- , Br - , I - ClO4 - AsF6 - CH3CO2 - CF3SO3 - , N(CF3SO2)2 - , C(CF2SO2)3 - Salts containing anions such as those listed above, or ions consisting of combinations thereof, may be dissolved or dissociated in organic solvents consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), gamma-butyrolactone (γ-butyrolactone), or mixtures thereof, but are not limited to these.

[0120] In one embodiment of the present invention, the electrochemical element separation membrane of the present invention can be similarly applied to lithium secondary batteries or sodium secondary batteries manufactured using lithium ions or sodium ions as the positive electrode active material, which includes the electrochemical element separation membrane.

[0121] Furthermore, unlike the lithium secondary batteries described above, another embodiment of the present invention is an all-solid-state battery.

[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. Examples of the device include 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.

[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 of the present invention are provided to give a more complete explanation of the present invention to a person of average skill in the art. [Examples]

[0124] 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.

[0125] As inorganic particles, D is 600 nm in size. 50 Al2O3 powder with specific particle sizes was prepared. Polyacrylic acid (K-702, Lubrizol) was used as the first binder polymer, and sodium carboxymethylcellulose (CMC-Na) (SG-L02, GLchem) was used as the dispersant.

[0126] The inorganic particles, first binder polymer, and dispersant prepared above were added to water in a weight ratio of 92:5:3. After that, the inorganic particles were crushed and dispersed to produce a slurry for the coating layer.

[0127] The coating layer slurry was applied to both sides of the porous polymer substrate using a doctor blade in a bar coating manner, and the coating layer was formed by drying it with a heat gun at 50°C.

[0128] A slurry for adhesive layers (solids content: 5% by weight) was prepared by adding and dispersing polyacrylic acid (K-702, Lubrizol), a polyacrylate copolymer, as the first polymer binder and an acrylic emulsion (BM-2510M, Zeon), a second polymer binder, in a weight ratio of 90:10 in water, the solvent.

[0129] The aforementioned adhesive layer slurry was applied to the coating layer by bar coating, and then dried to form an adhesive layer, thereby manufacturing a separation membrane for an electrochemical element.

[0130] A separation film for an electrochemical element was manufactured by applying the slurry for the adhesive layer to both sides of the surface of the coating layer using a doctor blade in a bar coating method, and then drying it with a heat gun using 50°C air to form an adhesive layer.

[0131] <Comparative Example 1> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that the slurry for the coating layer was prepared by mixing the inorganic particles, the first polymer binder, and the dispersant in a weight ratio of 85:12:3.

[0132] <Comparative Example 2> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that the slurry for the coating layer was prepared by mixing the inorganic particles, the first polymer binder, and the dispersant in a weight ratio of 97:0:3.

[0133] <Comparative Example 3> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that the slurry for the adhesive layer was prepared by mixing the first polymer binder and the second polymer binder in a weight ratio of 3:97.

[0134] <Comparative Example 4> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that an adhesive layer was not formed.

[0135] <Comparative Example 5> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that the slurry for the adhesive layer was prepared to contain only the second polymer binder.

[0136] <Comparative Example 6> In the separation membrane for the electrochemical element of Example 1, the separation membrane was manufactured in the same manner as in Example 1, except that the slurry for the adhesive layer was prepared to contain only the first polymer binder.

[0137] <Manufacturing of electrochemical elements> 1) Manufacturing of the positive electrode Cathode active material (LiNi 0.8 Mn 0.1 CO 0.1 A slurry for the positive electrode active material layer was prepared by mixing O2, a conductive material (carbon black), a dispersant (N-methylpyrrolidone, ADC-01, LG Chemical Co.), 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).

[0138] 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).

[0139] 3) Lamination process The separation films of the examples and comparative examples were interposed between the manufactured negative electrode and positive electrode and laminated, and an electrode assembly was obtained by performing a lamination process. The lamination process was performed using a hot press at 60°C and 6.5 MPa for 1 second.

[0140] <Experimental Example 1: Measurement of adhesive strength between electrode and separation membrane> The separation membranes from Example 1 and Comparative Examples 1-6 were cut to 70 mm (length) x 25 mm (width), and the negative electrodes and separation membranes were laminated using a press at 60°C, 6.5 MPa, and 1 second to prepare test specimens. The prepared test specimens were attached to a glass plate using double-sided tape, with the negative electrode facing the glass plate. The separation membrane portion of the test specimen was peeled off at a speed of 150 mm / min at 25°C at an angle of 180°, and the strength at this time was measured and summarized in Table 1 below.

[0141] <Experimental Example 2: Measurement of Adhesion Strength Between Porous Polymer Substrate and Coating Layer> The separation membranes from Example 1 and Comparative Examples 1-6 were cut to 70 mm (length) x 25 mm (width), and these prepared separation membranes were attached to a glass plate using double-sided tape. The separation membrane portion of the test specimen was peeled off at a speed of 150 mm / min at 25°C at an angle of 180°, and the strength at this time was measured and summarized in Table 1 below.

[0142] <Experimental Example 3: Measurement of particle size in coating layer slurry> The coating layer slurries produced during the manufacturing process of the separation membranes in Example 1 and Comparative Examples 1-6 were dispersed in a dispersion medium. These slurries were then introduced into a laser diffraction particle size analyzer (Microtrac S3500) to measure the difference in diffraction patterns corresponding to particle size as the particles passed through the laser beam. The particle size distribution was calculated and summarized in Table 1 below.

[0143] <Experimental Example 4: Measurement of Viscosity of Coating Layer Slurry> The viscosity of the coating layer slurries produced during the manufacturing process of the separation membranes in Example 1 and Comparative Examples 1-6 was measured at 25°C using a Brookfield LVDV-II+PRO Viscometer (cone-plate type, torque 90%, spindle #42, sample loading volume 1 mL) and the results are summarized in Table 1 below.

[0144] <Experimental Example 5: Measurement of the Number of Defects> The separation membranes of Example 1 and Comparative Examples 1-6 were cut into 0.5m x 0.5m sections, and the number of defects larger than 1μm was counted using an optical microscope to determine the number of defects per square meter. 2 After conversion, the results are summarized in Table 1 below.

[0145] [Table 1] Referring to Table 1, Example 1, an embodiment of the present invention, contained the first polymer binder in an appropriate amount in the coating layer, resulting in improved adhesion between the electrode and the separation membrane, and between the porous polymer substrate and the coating layer, with zero defects. In contrast, Comparative Example 1 contained an excessive amount of the first polymer binder in the coating layer, resulting in a rapid increase in the number of defects and an increase in the viscosity of the slurry for the coating layer. Comparative Example 2 did not contain the first polymer binder in the coating layer, resulting in a decrease in both the adhesion between the electrode and the separation membrane, and between the porous polymer substrate and the coating layer. Comparative Example 3 contained a small amount of the first polymer binder and an excessive amount of the second polymer binder in the adhesive layer, resulting in a decrease in both the adhesion between the electrode and the separation membrane, and between the adhesion between the porous polymer substrate and the coating layer. Comparative Example 4 did not contain an adhesive layer, resulting in a rapid decrease in the adhesion between the electrode and the separation membrane. Comparative Example 5, which contained only the second polymer binder in the adhesive layer, showed a decrease in both the adhesive strength between the electrode and the separation membrane, and the adhesive strength between the porous polymer substrate and the coating layer. Furthermore, Comparative Example 6, which contained only the first polymer binder in the adhesive layer, showed a rapid decrease in the adhesive strength between the electrode and the separation membrane.

[0146] Therefore, the separation membrane for an electrochemical element according to one embodiment of the present invention, and the electrochemical element containing the same, improve both the adhesion between the electrode and the separation membrane and the adhesion between the porous polymer substrate and the coating layer by adjusting the type and content of the polymer binder contained in the coating layer and the adhesive layer to reduce the number of defects, and by including it, improve the adhesion between the electrode and the separation membrane and the adhesion between the porous polymer substrate and the coating layer, thereby realizing a lower viscosity of the slurry during the manufacturing process and improving workability.

[0147] One embodiment of the present invention provides a separation membrane for an electrochemical element, comprising: 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, wherein the first polymer binder is in solution form, and the content of the first polymer binder in a portion of the coating layer adjacent to the porous polymer substrate is greater than the content of the first polymer binder in another portion separated from and facing the porous polymer substrate.

[0148] According to one embodiment of the present invention, the solubility of the second polymer binder in water may be less than the solubility of the first polymer binder in water.

[0149] According to one embodiment of the present invention, the first polymer binder may be one selected from the group consisting of polyacrylic acid, polyurethane, polyacrylonitrile, polyethylene glycol, polyacrylamide, polyvinyl alcohol, and combinations thereof.

[0150] According to one embodiment of the present invention, the second polymer binder may be in the form of particles.

[0151] One embodiment of the present invention provides a method for manufacturing a separation membrane for an electrochemical element, comprising the steps of: applying a coating layer slurry containing a first polymer binder and inorganic particles to at least one surface of a porous polymer substrate to form a coating layer; and applying an adhesive layer slurry containing a first polymer binder and a second polymer binder onto the coating layer to form an adhesive layer.

[0152] According to one embodiment of the present invention, the step of providing the coating layer and the step of providing the adhesive layer may further include drying steps.

[0153] According to one embodiment of the present invention, the content of the first polymer binder dissolved in the solvent in the coating layer slurry may be 0.1% by weight or more and 10% by weight or less.

[0154] According to one embodiment of the present invention, the content of the second polymer binder dissolved in the solvent in the slurry for the adhesive layer may be 5% by weight or more and 40% by weight or less.

[0155] According to one embodiment of the present invention, the average particle size (D) of the particles contained in the slurry for the coating layer 90 ) may be between 0.01 μm and 10.0 μm.

[0156] 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, wherein the adhesive strength between the porous polymer substrate and the coating layer is 30 gf / 25 mm or more.

[0157] According to one embodiment of the present invention, the adhesive strength between the porous polymer substrate and the coating layer may be about 5 gf / 25 mm or more greater than the adhesive strength between either the positive electrode or the negative electrode and the adhesive layer.

[0158] While preferred embodiments of the present invention have been described above with reference to the present invention, a person skilled in the art or a person with ordinary knowledge of the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and technical domain of the invention as described in the claims below. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the claims. [Explanation of Symbols]

[0159] 100: Separation membrane for electrochemical elements 110: Porous polymer base material 130: Coating layer 131: First Polymer Binder 133: Inorganic particles 150: Adhesive layer 151: Second Polymer Binder 300: Positive electrode 500: Negative electrode 1000: Electrochemical elements

Claims

1. Porous polymer base material; A coating layer comprising a first polymer binder and inorganic particles, provided on at least one surface of the porous polymer substrate; and The coating layer is provided and includes an adhesive layer containing a second polymer binder, The first polymer binder is in solution form, A separation membrane for an electrochemical element, wherein the amount of the first polymer binder contained in a portion of the coating layer adjacent to the porous polymer substrate is greater than the amount of the first polymer binder contained in other portions separated from and facing the porous polymer substrate.

2. The separation membrane for an electrochemical element according to claim 1, wherein the solubility of the second polymer binder in water is less than the solubility of the first polymer binder in water.

3. The separation membrane for an electrochemical element according to claim 1, wherein the first polymer binder is one selected from the group consisting of polyacrylic acid, polyurethane, polyacrylonitrile, polyethylene glycol, polyacrylamide, polyvinyl alcohol, and combinations thereof.

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

5. A manufacturing method for producing a separation membrane for an electrochemical element according to any one of claims 1 to 4, A step of applying a coating layer slurry containing a first polymer binder and inorganic particles to at least one surface of a porous polymer substrate to provide a coating layer; and A method for manufacturing a separation membrane for an electrochemical element, comprising the step of applying an adhesive layer slurry containing a first polymer binder and a second polymer binder onto the coating layer to form an adhesive layer.

6. The method for producing a separation membrane for an electrochemical element according to claim 5, further comprising the steps of drying after the step of providing the coating layer and the step of providing the adhesive layer.

7. The method for producing a separation membrane for an electrochemical element according to claim 5, wherein the content of the first polymer binder dissolved in the solvent in the slurry for the coating layer is 0.1% by weight or more and 10% by weight or less.

8. The method for producing a separation membrane for an electrochemical element according to claim 5, wherein the content of the first polymer binder dissolved in the solvent in the slurry for the adhesive layer is 5% by weight or more and 40% by weight or less.

9. The average particle size (D) of the inorganic particles contained in the slurry for the coating layer ９０ The method for producing a separation membrane for an electrochemical element according to claim 5, wherein the thickness of the membrane is 0.01 μm or more and 10.0 μm or less.

10. The device comprises a positive electrode; a negative electrode; and a separation membrane for an electrochemical element according to any one of claims 1 to 4, interposed between the positive electrode and the negative electrode. An electrochemical element having an adhesive strength of 30 gf / 25 mm or more between the porous polymer substrate and the coating layer.

11. The electrochemical element according to claim 10, wherein the adhesive strength between the porous polymer substrate and the coating layer is 5 gf / 25 mm or greater than the adhesive strength between either the positive electrode or the negative electrode and the adhesive layer.

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