Method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries

Abstract

The present invention relates to a method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries. According to the present invention, a method for manufacturing an electrode-integrated separation membrane is provided that has excellent interlayer bonding durability and can minimize defects such as pinholes.

Description

[Technical Field]

[0001] Mutual citation with related applications This application claims priority rights based on Korean Patent Application No. 10-2023-0142205 dated October 23, 2023, and Korean Patent Application No. 10-2024-0143124 dated October 18, 2024, and all content disclosed in the documents of said Korean Patent Applications is included herein as part of this specification.

[0002] This invention relates to a method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries. [Background technology]

[0003] The increasing sophistication of mobile phones, laptops, tablet computers, power banks, electric vehicles, and personal mobility devices is driving a growing demand for rechargeable batteries used as their power sources. In particular, lithium-ion batteries, which have high operating voltages and high energy density per unit weight, are the most widely used.

[0004] Lithium-ion batteries generally have a structure in which a chargeable and dischargeable electrode assembly, consisting of a positive electrode, a separator membrane, and a negative electrode structure, is mounted in a battery case. The positive and negative electrodes are manufactured by applying a slurry containing electrode active material to one or both sides of a metal current collector, followed by drying and rolling.

[0005] The separation membrane is one of the crucial factors determining the lifespan of a secondary battery, electrically insulating the positive and negative electrodes. The separation membrane requires ion permeability and mechanical strength to allow the electrolyte to pass through smoothly. As the applications of high-energy lithium-ion secondary batteries expand, the demands for safety of the separation membrane at high temperatures are also increasing.

[0006] Typically, separation membranes consisting of a substrate and an inorganic coating layer do not have sufficient adhesion to electrodes due to their material properties. This leads to problems such as partial lifting or wrinkling at the interface between the electrode and the separation membrane. Furthermore, polyolefins, which are commonly used as the substrate, have problems with thermal stability, such as melting at high temperatures.

[0007] To address these problems, a method has been proposed in which the substrate is removed and the separation membrane is constructed solely from an inorganic coating film. However, such a separation membrane still lacks sufficient adhesion to the electrode and has significantly low insulation properties, making it vulnerable to internal short circuits when applied to electrochemical elements. Such a separation membrane has a fatal drawback: its low tensile strength and elongation allow it to easily rupture, causing minute short circuits within the electrode assembly. Furthermore, the condition of the electrode substrate (e.g., porosity and surface roughness of the electrode active material layer) can lead to non-uniformity of the separation membrane coating and resulting defects. [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention provides a method for manufacturing an electrode-integrated separation membrane that offers excellent interlayer bonding durability and minimizes defects such as pinholes. [Means for solving the problem]

[0009] According to one embodiment of the present invention, The steps include applying a binder solution containing a first polymer binder onto an electrode substrate to form a binder coating layer, and The process includes the step of applying a slurry containing a second polymer binder and inorganic fine particles onto the binder coating layer to form a porous layer; The binder solution has a viscosity of 1000 cP to 9500 cP at 25°C. A method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries is provided.

[0010] The method for manufacturing the electrode-integrated separation membrane for lithium secondary batteries according to the embodiment of the present invention will be described in more detail below.

[0011] The terms and words used herein and in the claims shall not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best describe their inventions.

[0012] In this specification, unless otherwise defined, all technical and scientific terms have the same meaning as those generally understood by an ordinary person skilled in the art to which the present invention belongs. The terms used in the description of the present invention are solely for the purpose of effectively describing certain specific examples and are not intended to limit the present invention.

[0013] In this specification, the singular form used includes the plural form unless the text explicitly indicates the opposite.

[0014] In this specification, the meaning of “including” embodies a particular characteristic, domain, integer, step, operation, element and / or component, and does not exclude the presence or addition of other particular characteristics, domains, integers, steps, operations, elements, components and / or groups.

[0015] The present invention can be modified in various ways and may take many forms; therefore, specific embodiments are illustrated and described in detail below. However, this should not be understood as limiting the invention to any particular form of disclosure, but rather as including all modifications, equivalents, or substitutions that fall within the aforementioned concept and technical scope.

[0016] In this specification, when the positional relationship between two parts is described using expressions such as "on top," "at the top," "below," or "to the side," unless the expression "directly" or "directly" is used, one or more other parts may be located between the two parts.

[0017] In this specification, when temporal relationships are described using expressions such as "after," "following," "next," or "before," non-continuous cases can be included unless the expressions "immediately" or "directly" are used.

[0018] In this specification, the term “at least one” should be understood to include all possible combinations of one or more related items.

[0019] In this specification, the term "a layer is bonded to another layer via another layer" means that the layer and the other layer are laminated and bonded by the other layer interposed in at least a portion of the area between the layer and the other layer.

[0020] Furthermore, in this specification, terms including ordinal numbers, such as "first" and "second," are used for the purpose of distinguishing one component from another, and are not limited by such ordinal numbers. For example, within the scope of the rights of this invention, the first component may also be named the second component, and similarly, the second component may also be named the first component.

[0021] As explained in the background art of this invention, separation membranes composed solely of inorganic coating films have low mechanical properties, which limits their ability to be manufactured in the form of free-standing thin films.

[0022] Due to these limitations, a method has been proposed for manufacturing an electrode-integrated separation membrane by coating an inorganic coating composition onto an electrode. However, this method may result in non-uniformity of the separation membrane coating and resulting defects depending on the condition of the electrode (e.g., porosity and surface roughness).

[0023] As a result of the inventors' ongoing research, it has been confirmed that an electrode-integrated separation membrane can be provided that exhibits excellent interlayer bonding durability and minimizes defects such as pinholes using the following manufacturing method.

[0024] According to one embodiment of the present invention, The steps include applying a binder solution containing a first polymer binder onto an electrode substrate to form a binder coating layer, and The process includes the step of applying a slurry containing a second polymer binder and inorganic fine particles onto the binder coating layer to form a porous layer; The binder solution has a viscosity of 1000 cP to 9500 cP at 25°C. A method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries is provided.

[0025] The manufacturing method provides an electrode-integrated separation membrane for lithium secondary batteries by sequentially forming the binder coating layer and the porous layer on the electrode substrate.

[0026] By bonding the electrode substrate and the porous layer via the binder coating layer, superior interlayer bonding durability can be ensured compared to a manufacturing method in which the porous layer is directly formed on the electrode substrate.

[0027] When forming the porous layer directly on the electrode substrate, the coating properties of the slurry used to form the porous layer may become uneven depending on the porosity and surface roughness of the electrode substrate, and serious defects such as pinholes may occur during the coating process.

[0028] However, the above manufacturing method allows for the uniform and flat formation of the porous layer on the binder coating layer by sequentially forming the binder coating layer and the porous layer on the electrode substrate, thereby minimizing defects such as pinholes.

[0029] In order to exhibit the above-mentioned properties, the binder solution preferably has a viscosity of 1000 cP to 10000 cP at 25°C.

[0030] Specifically, the binder solution may have a viscosity of 1000 cP or more, or 3500 cP or more, or 5000 cP or more, or 5500 cP or more at 25°C; and 9500 cP or less, or 9000 cP or less, or 8500 cP or less, or 8000 cP or less.

[0031] In the step of coating the electrode substrate with the binder solution, in order to prevent the occurrence of pinholes due to the diffusion of solvent and air bubbles, the binder solution is preferably 1000 cP or more, or 3500 cP or more, or 5000 cP or more at 25°C. However, if the viscosity of the binder solution is excessively high, the coating properties of the binder solution may decrease, making it difficult to achieve the desired properties of the binder coating layer. Therefore, it is preferable that the binder solution has a viscosity of 9500 cP or less, or 9000 cP or less, or 8500 cP or less, or 8000 cP or less at 25°C.

[0032] Preferably, the binder solution may have a viscosity of 1000 cP to 9500 cP, or 3500 cP to 9500 cP, or 5000 cP to 9500 cP, or 5500 cP to 9500 cP, or 5500 cP to 9000 cP, or 5500 cP to 8500 cP, or 5500 cP to 8000 cP at 25°C.

[0033] The viscosity of the binder solution may be measured using a viscometer and a rheometer and conventional equipment. For example, the viscosity may be measured using a Brookfield viscometer (RV, #5, 50 rpm, 25°C) according to the ASTM D 2196 test method.

[0034] According to one embodiment, the process involves applying a binder solution containing a first polymer binder onto an electrode substrate to form a binder coating layer.

[0035] The electrode substrate may be an electrode substrate for a negative electrode or a positive electrode. The electrode substrate includes an electrode active material layer laminated on an electrode current collector layer.

[0036] The electrode current collector layer can be made of an electrode current collector known to be conductive in the art to which the present invention belongs without causing a chemical change in the lithium secondary battery. For example, the electrode current collector may be made of stainless steel; aluminum; nickel; titanium; calcined carbon; or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc.

[0037] Preferably, the electrode current collector may have a thickness of 3 μm to 500 μm. To enhance adhesion to the electrode material, the electrode current collector may have fine irregularities formed on its surface. The electrode current collector can take various forms, such as film, sheet, foil, net, porous body, foam, or nonwoven fabric.

[0038] The electrode active material layer comprises an electrode material composition which is a mixture of an electrode active material, a conductive material, and a binder.

[0039] The conductive material can be used to impart electronic conductivity to the electrode.

[0040] The conductive material can be any material that has electronic conductivity without causing a chemical change in the lithium secondary battery, without any special limitations. Non-limiting examples of the conductive material include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; graphite such as natural graphite or artificial graphite; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One or more of the above-mentioned examples may be used as the conductive material.

[0041] The content of the conductive material may be adjusted to exhibit an appropriate level of conductivity without causing a decrease in the capacity of the lithium secondary battery. Preferably, the content of the conductive material may be 1% to 10% by weight or 1% to 5% by weight relative to the total weight of the electrode material composition.

[0042] The binder is used to ensure that the electrode material composition adheres well to the electrode current collector.

[0043] As non-limiting examples, the binder may be polyvinyl alcohol, polyacrylate, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic styrene-butadiene rubber, epoxy resin, nylon resin, etc. One or a mixture of two or more of the above-mentioned examples may be used as the binder.

[0044] The content of the binder may be adjusted within a range that exhibits an appropriate level of adhesiveness and does not cause a reduction in the capacity of the lithium secondary battery. Preferably, the content of the binder may be 1% to 10% or 1% to 5% by weight based on the total weight of the electrode material composition.

[0045] When the electrode substrate is the positive electrode portion, as the positive electrode active material, any material capable of reversible insertion and desorption of lithium ions can be used without particular limitation.

[0046] As an example, the positive electrode active material may be a composite oxide or phosphate containing lithium and a metal such as cobalt, manganese, nickel, iron, or a combination thereof.

[0047] As another example, the positive electrode active material may be a compound represented by any one of the following chemical formulas: Li a A 1-b R b D2(0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5); Li a E 1-b R b O 2-c D c (0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); LiE 2-b R b O 4-c D c (0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); Li a Ni 1-b-c Co b R c D d (0.9 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 < d ≦ 2); Li a Ni 1-b-c Co b R c O 2-d Z d (0.9 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 < d < 2); Li a Ni 1-b-c Co b R c O 2-dZ2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni 1-b-c Mn b R c D d (0.90≦a≦1.8,0≦b≦0.5,0≦c≦0.05,0 <d≦2);Li a Ni 1-b-c Mn b R c O 2-d Z d (0.90≦a≦1.8,0≦b≦0.5,0≦c≦0.05,0 <d<2);Li a Ni 1-b-c Mn b R c O 2-d Z2(0.90≦a≦1.8、0≦b≦0.5、0≦c≦0.05、0 <d<2);Li a Ni b E c G d O2(0.90≦a≦1.8;0≦b≦0.9;0≦c≦0.5;0.001≦d≦0.1.);Li a Ni b Co. Co c Mn d G e O2(0.90≦a≦1.8、0≦b≦0.9、0≦c≦0.5、0≦d≦0.5、0.001≦e≦0.1);Li a NiG b O2(0.90≦a≦1.8;0.001≦b≦0.1);Li a CoG b O2(0.90≦a≦1.8;0.001≦b≦0.1);Li a MnG b O2(0.90≦a≦1.8;0.001≦b≦0.1);Li a Mn2G b O4(0.90≦a≦1.8、0.001≦b≦0.1);QO2;QS2;LiQS2;V2O5;LiV2O5;LiTO2;LiNiVO4;Li (3-f) J2(PO4)3(0≦f≦2);Li (3-f) Fe2(PO4)3(0≦f≦2);

[0048] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0049] A positive electrode active material having a coating layer on its surface can also be used, or a mixture of the positive electrode active material and a positive electrode active material having a coating layer can be used. The coating elements included in the coating layer may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof.

[0050] According to one embodiment, the positive electrode active material may be present in an amount of 80% to 95% by weight relative to the total weight of the electrode material composition. Preferably, the content of the positive electrode active material may be 82% to 95% by weight, or 82% to 93% by weight, or 85% to 93% by weight, or 85% to 90% by weight relative to the total weight of the electrode material composition.

[0051] When the electrode substrate is the negative electrode portion, the negative electrode active material may include a substance capable of reversibly intercalating and deintercalating lithium ions, lithium metal, an alloy of lithium metal, a substance capable of doping and dedoping lithium, and a transition metal oxide.

[0052] Examples of materials capable of reversibly intercalating and deintercalating lithium ions include crystalline carbon, amorphous carbon, or mixtures thereof as carbonaceous materials. Specifically, the carbonaceous material may be natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitches, mesophase pitch-based carbon fiber, meso-carbon microbeads, petroleum or coal tar pitch-derived cokes, soft carbon, and hard carbon.

[0053] The lithium metal alloy may be an alloy of lithium with a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, Bi, Ga, and Cd.

[0054] The substances capable of being doped and undoped with lithium may be Si, Si-C composite, SiOx (0 < x < 2), Si-Q alloy (where Q is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Si is excluded), Sn, SnO2, Sn-R alloy (where R is an element selected from the group consisting of alkali metals, alkaline earth metals, group 13 elements, group 14 elements, group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof; provided that Sn is excluded), etc. And as the substances capable of being doped and undoped with lithium, at least one of the above examples and SiO2 can be mixed and used. Q and R may be Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, etc.

[0055] And the transition metal oxide may be vanadium oxide, lithium vanadium oxide, lithium titanium oxide, etc.

[0056] Preferably, the negative electrode active material can contain one or more compounds selected from the group consisting of carbonaceous substances and silicon compounds. Here, the carbonaceous substance is one or more substances selected from the group consisting of the exemplified natural graphite, artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch, mesophase pitch-based carbon fiber, carbon microspheres, petroleum or coal-based coke, softened carbon, and hardened carbon. And the silicon compound may be a compound containing Si exemplified above, that is, Si, Si-C composite, SiOx (0 < x < 2), the Si-Q alloy, a mixture thereof, or a mixture of at least one of these and SiO2.

[0057] According to one embodiment, the negative electrode active material may be present in an amount of 85% to 98% by weight relative to the total weight of the electrode material composition. Preferably, the content of the negative electrode active material may be 85% to 97% by weight, or 87% to 97% by weight, or 87% to 95% by weight, or 90% to 95% by weight, relative to the total weight of the negative electrode material.

[0058] According to one embodiment, the thickness of the electrode active material layer is preferably adjusted to a range of 5 μm to 500 μm, 5 μm to 450 μm, or 10 μm to 450 μm in order to achieve appropriate performance.

[0059] On the other hand, the binder solution containing the first polymer binder is applied to the electrode substrate, preferably to the electrode active material layer. The binder solution is applied to the entire surface of one side of the electrode substrate.

[0060] The binder solution contains a first polymer binder as a solute. The first polymer binder may gel upon liquid electrolyte impregnation, exhibiting a high degree of electrolyte impregnation (degree of swelling). The electrolyte injected after the lithium secondary battery is assembled penetrates the first polymer binder, and the first polymer binder, which holds the absorbed electrolyte, acquires electrolyte ion conducting ability.

[0061] According to one example, the first polymer binder is polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), spandex, butyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyimide, polyetherimide, ethyl It is one or more compounds selected from the group consisting of vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethylcellulose, cyanoethyl sucrose, pullulan, carboxymethylcellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluororubber.

[0062] According to one example, the binder solution may contain, as a solvent, one or more selected from the group consisting of acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, dimethylformamide, 1,3-dioxolane, and sulfolane.

[0063] According to one embodiment, the binder solution preferably contains 3.5% to 7.0% by weight of the first polymer binder based on the total weight of the solution.

[0064] Specifically, the binder solution may contain the first polymer binder in an amount of 3.5% or more by weight, or 3.6% or more by weight, or 3.7% or more by weight, or 3.8% or more by weight, or 3.9% or more by weight, or 4.0% or more by weight; and 7.0% or less by weight, or 6.9% or less by weight, or 6.8% or less by weight, 6.7% or less by weight, or 6.6% or less by weight, based on the total weight of the solution.

[0065] In the step of coating the electrode substrate with the binder solution, in order to prevent the occurrence of pinholes due to the diffusion of solvent and bubbles, the binder solution preferably contains 3.5% by weight or more, or 3.6% by weight or more, or 3.7% by weight or more, or 3.8% by weight or more, or 3.9% by weight or more, or 4.0% by weight or more of the first polymer binder. However, in order to prevent the viscosity of the binder solution from becoming excessively high, the binder solution preferably contains 7.0% by weight or less, or 6.9% by weight or less, or 6.8% by weight or less, 6.7% by weight or less, or 6.6% by weight or less of the first polymer binder.

[0066] Preferably, the binder solution may contain 3.5% to 7.0% by weight, or 3.6% to 7.0% by weight, or 3.6% to 6.9% by weight, or 3.7% to 6.9% by weight, or 3.7% to 6.8% by weight, or 3.8% to 6.8% by weight, or 3.8% to 6.7% by weight, or 3.9% to 6.7% by weight, or 3.9% to 6.6% by weight, or 4.0% to 6.6% by weight of the first polymer binder.

[0067] According to one embodiment, a conventional coating method known in the art to which the present invention belongs can be applied to the electrode substrate. For example, the application of the binder solution may be done by spin coating, dip coating, die coating, roll coating, comma coating, gravure coating, bar coating, curtain coating, screen printing, inkjet printing, doctor blade, or a mixture thereof.

[0068] According to one embodiment, in the step of forming the binder coating layer, the binder solution is preferably applied to the electrode substrate to a thickness of 10 μm to 50 μm (wet film thickness). Within this thickness range, a binder coating layer with excellent peel strength can be formed without increasing electrical resistance.

[0069] Specifically, the binder solution may be applied to the electrode substrate to a thickness of 10 μm or more or 15 μm or more; and 50 μm or less or 45 μm or less.

[0070] In order to enable the aforementioned properties to be exhibited in the binder coating layer, it is preferable that the binder solution be applied to the electrode substrate to a thickness of 10 μm or more or 15 μm or more. However, if the thickness of the binder coating layer is excessively thick, the electrical resistance may increase, potentially degrading the performance of the lithium secondary battery. Therefore, it is preferable that the binder solution be applied to the electrode substrate to a thickness of 50 μm or less or 45 μm or less.

[0071] Preferably, the binder solution may be applied to the electrode substrate to a thickness of 10 μm to 50 μm, 15 μm to 50 μm, or 15 μm to 45 μm.

[0072] According to one embodiment, the binder coating layer is formed by applying the binder solution to the electrode substrate and drying it. The drying is preferably carried out at a temperature of 50°C to 150°C, 60°C to 150°C, 60°C to 120°C, or 65°C to 110°C. If the drying temperature does not meet the above range, the drying efficiency may decrease or changes in the morphology of each layer may occur, potentially causing defects.

[0073] The binder coating layer formed through the above steps may have a thickness of 0.3 μm or more, or 0.5 μm or more; and 5 μm or less, or 3 μm or less, in order to exhibit the aforementioned properties. Preferably, the binder coating layer may have a thickness of 0.3 μm to 5 μm, or 0.5 μm to 5 μm, or 0.5 μm to 3 μm.

[0074] Following the step of forming the binder coating layer, a step is performed in which a slurry containing a second polymer binder and inorganic fine particles is applied onto the binder coating layer to form a porous layer.

[0075] The porous layer is formed by applying a slurry containing the second polymer binder and inorganic fine particles onto the binder coating layer. The porous layer has appropriate porosity and insulating properties and can function as a separation film layer in a lithium secondary battery.

[0076] The slurry applied to form the porous layer includes the second polymer binder and inorganic fine particles.

[0077] The second polymer binder may gel upon liquid electrolyte impregnation, exhibiting a high degree of electrolyte penetration (degree of swelling). The electrolyte injected after the lithium secondary battery is assembled penetrates the second polymer binder, and the second polymer binder, which holds the absorbed electrolyte, acquires electrolyte ion conductivity.

[0078] According to one example, the second polymer binder is polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), spandex, butyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyimide, polyetherimide, ethyl It is one or more compounds selected from the group consisting of vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethylcellulose, cyanoethyl sucrose, pullulan, carboxymethylcellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluororubber.

[0079] According to one embodiment, the slurry applied to form the porous layer may contain, as a solvent, one or more selected from the group consisting of acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, dimethylformamide, 1,3-dioxolane, and sulfolane.

[0080] The inorganic fine particles contained in the slurry form fine pores due to the empty spaces between the particles, maintain their physical form at high temperatures, and are electrochemically stable.

[0081] It is preferable that the inorganic fine particles do not undergo oxidation and / or reduction reactions within the operating voltage range of the secondary battery (for example, 0 to 5V relative to Li / Li+). It is preferable that the inorganic fine particles have a high electrolyte ion transfer capacity. It is preferable that the inorganic fine particles have as low a density as possible so that they can be well dispersed in the polymer binder. Furthermore, it is preferable that the inorganic fine particles have a high dielectric constant so that they can contribute to increasing the degree of dissociation of the electrolyte salt in the electrolyte.

[0082] Preferably, the inorganic fine particles may be one or more selected from the group consisting of inorganic particles having a dielectric constant of 1 or more, piezoelectric inorganic particles, and inorganic particles having lithium ion transport capability.

[0083] As an example, inorganic particles such as SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, boehmite (AlO(OH)), Al(OH)3, TiO2, and SiC have a dielectric constant of 1 or more and can be suitably applied to the inorganic fine particles.

[0084] As another example, the piezoelectric inorganic particles are insulators at normal pressure, but become conductive due to a change in their internal structure when a certain pressure is applied. The piezoelectric inorganic particles have a high dielectric constant, with a dielectric constant of 100 or more. Furthermore, when a certain pressure is applied to the piezoelectric inorganic particles for tension or compression, an electric charge is generated, causing one side to become positively (+) charged and the other side negatively (-), resulting in a potential difference between the two sides. Due to the properties of the piezoelectric inorganic particles, when an internal short circuit occurs in the electrodes of a secondary battery due to external shock, direct contact between the positive and negative electrodes can be prevented, leading to a gradual decrease in voltage and improved safety. Examples of the piezoelectric inorganic particles include BaTiO3, Pb(Zr,Ti)O3(PZT), and Pb 1-x La x Zr 1-y Ti y O3(PLZT), Pb(Mg 1 / 3 Nb 2 / 3Inorganic particles such as O3-PbTiO3 (PMN-PT) and HfO2 can be preferably applied.

[0085] As another example, the inorganic particles having the lithium ion transfer ability refer to inorganic particles that contain lithium element, do not occlude lithium, and have the function of moving lithium ions. The inorganic particles having the lithium ion transfer ability can improve the conductivity of lithium ions in the battery. Examples of such inorganic particles include Li3PO4, Li x Ti y (PO4)3 (0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3 (0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y (0 < x < 4, 0 < y < 13), Li x La y TiO3 (0 < x < 2, 0 < y < 3), Li x Ge y P z S w (0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), Li x N y (0 < x < 4, 0 < y < 2), Li x Si y S z (0 < x < 3, 0 < y < 2, 0 < z < 4), and Li x P y S z (0 < x < 3, 0 < y < 3, 0 < z < 7) and the like of inorganic particles can be cited as examples.

[0086] Preferably, the inorganic fine particles are SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, AlO(OH), Al(OH)3, TiO2, SiC, BaTiO3, Pb(Zr,Ti)O3, Pb 1-x La x Zr 1-y Ti y O3, Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3, HfO2, Li3PO4, Lix Ti y (PO4)3(0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3(0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP)<​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​According to one embodiment, the slurry preferably has a solid content of 30% to 80% by weight.

[0090] If the solid content of the slurry is excessively high, it may cause an increase in viscosity and reduce the coating properties of the slurry. However, if the solid content of the slurry is excessively low, pinholes may occur during coating with the slurry, which may reduce the drying efficiency of the slurry coating.

[0091] Specifically, the solid content of the slurry may be 30% by weight or more, or 35% by weight or more; and 80% by weight or less, or 75% by weight or less. Preferably, the solid content of the slurry may be 30% by weight to 80% by weight, or 35% by weight to 80% by weight, or 35% by weight to 75% by weight.

[0092] According to one embodiment, a conventional coating method known in the art to which the present invention belongs can be applied to the method of applying the slurry onto the binder coating layer. For example, the application of the slurry may be done by spin coating, dip coating, die coating, roll coating, comma coating, gravure coating, bar coating, curtain coating, screen printing, inkjet printing, doctor blade, or a mixture thereof.

[0093] The thickness of the slurry formed on the binder coating layer may be adjusted considering the composition of the slurry and the thickness of the porous layer to be ultimately formed. The thickness of the porous layer is preferably adjusted to a range of 10 μm to 100 μm, 10 μm to 80 μm, or 10 μm to 50 μm for the achievement of appropriate performance.

[0094] According to one embodiment, the porous layer is formed by applying the slurry onto the binder coating layer and drying it. The drying is preferably carried out at a temperature of 50°C to 150°C, 60°C to 150°C, 60°C to 120°C, or 65°C to 110°C. If the drying temperature does not meet the above range, the drying efficiency may decrease or changes in the morphology of each layer may occur, potentially causing defects.

[0095] According to one embodiment, the porous layer formed by the method may contain 1 to 90% by weight of the polymer binder and 10 to 99% by weight of the inorganic fine particles. It is preferable that the inorganic fine particles are present in an amount of 10% by weight or more so that the porous layer is given appropriate porosity and insulating properties. However, if the inorganic fine particles are present in excess, the mechanical properties of the porous layer may deteriorate due to weakened adhesive strength. Therefore, it is preferable that the inorganic fine particles are present in an amount of 99% by weight or less.

[0096] According to one embodiment, it is preferable that the porous layer has a porosity within an appropriate range for the characteristics of the porous layer to be expressed. If the porosity of the porous layer is excessively high, an internal short circuit may occur during charging and discharging of the lithium secondary battery. Therefore, it is preferable that the porosity of the porous layer 30 is 60% or less.

[0097] According to another embodiment of the present invention, a lithium secondary battery is provided that includes an electrode-integrated separator membrane for lithium secondary batteries manufactured by the method described above.

[0098] As an example, the lithium secondary battery may include an electrode assembly comprising a relative electrode disposed on the porous layer of the electrode-integrated separation membrane; an electrolyte impregnated in the electrode assembly; and a battery case that seals and houses the electrode assembly and the electrolyte.

[0099] The lithium secondary battery, by incorporating the electrode assembly described above, can exhibit excellent durability and stable performance.

[0100] The lithium secondary battery can have various forms, such as prismatic, cylindrical, and pouch-type.

[0101] The lithium secondary battery can be used as an energy source with improved performance and safety in the field of portable electronic devices such as mobile phones, laptops, tablet computers, mobile batteries, and digital cameras; and in the field of transportation such as electric vehicles, electric motorcycles, and personal mobility devices.

[0102] According to one embodiment, the electrolyte can be any electrolyte known to be applicable to lithium secondary batteries in the art to which the present invention belongs, without any special limitations. For example, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, or the like.

[0103] Specifically, the electrolyte may include a non-aqueous organic solvent and a lithium salt.

[0104] The non-aqueous organic solvent may be used without any particular restrictions, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0105] Specifically, the non-aqueous organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether and tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, which can include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; and sulfolanes, etc.

[0106] Among the above examples, carbonate-based solvents can be preferably used as the non-aqueous organic solvent.

[0107] In particular, considering the battery's charge / discharge performance and compatibility with the positive electrode material, a mixture of a cyclic carbonate (e.g., ethylene carbonate, propylene carbonate) having high ionic conductivity and high dielectric constant and a low-viscosity linear carbonate (e.g., ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate) can be preferably used as the non-aqueous organic solvent. In this case, mixing the cyclic carbonate and the linear carbonate in a volume ratio of 1:1 to 1:9 may be advantageous for achieving the aforementioned performance.

[0108] Furthermore, as the non-aqueous organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 1:2 to 1:10; or a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1 to 3:1 to 9:1 can be preferably used.

[0109] The lithium salt contained in the electrolyte dissolves in the non-aqueous organic solvent and acts as a source of lithium ions within the battery, enabling the basic operation of a lithium secondary battery and promoting the movement of lithium ions between the positive and negative electrodes.

[0110] Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiFSI, LiTFSI, LiCl, LiI, and LiB(C2O4)2, etc. Preferably, the lithium salt may be LiPF6, LiFSI, LiTFSI, and mixtures thereof.

[0111] The lithium salt may be included in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt included within this concentration range imparts appropriate conductivity and viscosity to the electrolyte, thereby enabling it to exhibit excellent electrolyte performance.

[0112] The electrolyte may selectively contain additives intended to improve battery life characteristics, suppress battery capacity reduction, and improve battery discharge capacity.

[0113] For example, the additive may be a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethyl phosphate, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. The additive may be present in an amount of 0.1% to 5% by weight relative to the total weight of the electrolyte. [Effects of the Invention]

[0114] According to the present invention, a method for manufacturing an electrode-integrated separation membrane is provided that offers excellent interlayer bonding durability and minimizes defects such as pinholes. [Modes for carrying out the invention]

[0115] The operation and effects of the present invention will be described in more detail below through specific embodiments of the present invention. However, these are presented as examples for understanding the present invention. It is not intended that the scope of the present invention is limited in any sense through the following embodiments, and it will be obvious to an ordinary person that various changes and modifications are possible within the scope and technical concept of the present invention. [Examples]

[0116] Example 1 An electrode material composition was prepared consisting of 95.6% by weight of an active material composed of 90% by weight of graphite active material and 10% by weight of SiO2, which is a mixture of artificial graphite and natural graphite in a ratio of 3:7; 1% by weight of acetylene black as a conductive material; and 1.1% by weight of carboxymethylcellulose (CMC) and 2.3% by weight of styrene-butadiene rubber (SBR) as binders. Using a comma coater, the electrode material composition was applied to one side of a copper current collector with a thickness of 8 μm. This was dried and rolled at 130°C to prepare a negative electrode plate with a laminated negative electrode active material layer. The negative electrode active material layer was formed with a porosity of 24% and a thickness of 90 μm.

[0117] A binder solution was prepared by dissolving 6% by weight of the polymeric binder poly(vinylidene fluoride-co-hexafluoropropylene) in N-methyl-2-pyrrolidone (NMP) based on the total weight of the solution. Using a comma coater, the binder solution was applied to a thickness of 15 μm onto the negative electrode active material layer of the negative electrode plate. This was dried at a temperature of 100°C to form a binder coating layer with a thickness of 2.4 μm on the negative electrode active material layer.

[0118] An inorganic fine particle dispersion with a solid content of 40% was prepared by mixing inorganic fine particles, AlO(OH), with N-methyl-2-pyrrolidone (NMP). At this time, the particle size D50 of the inorganic fine particles, measured with a particle size analyzer, was analyzed to be 300 nm. A polymer solution was prepared by dissolving 5 wt% of the polymer binder, poly(vinylidene fluoride-co-hexafluoropropylene), in N-methyl-2-pyrrolidone (NMP). Using a homogenizer mixer, the inorganic fine particle dispersion and the polymer solution were uniformly mixed to obtain a slurry with a solid content of 40 wt%. Using a comma coater, the slurry was applied to the binder coating layer to a thickness of 40 μm. This was dried at a temperature of 130°C to form a porous layer with a thickness of 14 μm on the binder coating layer.

[0119] The negative electrode plate, on which the binder coating layer and the porous layer were formed, was punched out to a size of 31 × 43 mm using a die punching machine to prepare the negative electrode portion (electrode-integrated separation membrane).

[0120] A slurry was prepared by placing a mixture consisting of 94 wt% LiNiCoMnO2 (Ni:Co:Mn=8:1:1) as the positive electrode active material, 3 wt% conductive carbon black (Super P; IMERYS Graphite & Carbon) as the conductive material, and 3 wt% polyvinylidene fluoride as the binder into an NMP and dispersing it uniformly. The slurry was applied to one side of an aluminum current collector, and this was dried and rolled to prepare a positive electrode plate with a laminated positive electrode active material layer. The positive electrode plate was punched out to a size of 30 × 42 mm using a die punching machine to prepare the positive electrode portion.

[0121] An electrode opposing body was formed by placing the positive electrode active material layer of the positive electrode portion in contact with the porous layer of the negative electrode portion, and the electrode assembly was manufactured by pressure lamination at 90°C.

[0122] The electrode assembly was placed in a pouch to form a small cell, and an electrolyte solution was injected into the pouch to manufacture five lithium secondary batteries.

[0123] In this case, the electrolyte used was a non-aqueous organic solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:7, in which 0.5 M LiFSI, 0.7 M LiPF6, and 2% by weight of vinylene carbonate (VC) were dissolved.

[0124] Example 2 An electrode-integrated separation membrane for a lithium secondary battery and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the binder solution was applied to the negative electrode active material layer of the negative electrode plate to a thickness of 40 μm using a comma coater.

[0125] Example 3 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene), a polymer binder, was dissolved in NMP at a concentration of 6.6% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0126] Example 4 An electrode-integrated separation membrane for a lithium secondary battery and a lithium secondary battery were manufactured in the same manner as in Example 3, except that the binder solution was applied to the negative electrode active material layer of the negative electrode plate to a thickness of 40 μm using a comma coater.

[0127] Example 5 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene), a polymer binder, was dissolved in NMP at a concentration of 4.0% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0128] Example 6 An electrode-integrated separation membrane for a lithium secondary battery and a lithium secondary battery were manufactured in the same manner as in Example 5, except that the binder solution was applied to the negative electrode active material layer of the negative electrode plate to a thickness of 40 μm using a comma coater.

[0129] Comparative Example 1 An electrode-integrated separation membrane for a lithium secondary battery and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the binder coating layer was not formed on the negative electrode active material layer.

[0130] Comparative Example 2 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene) was dissolved in NMP at a concentration of 1.0% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0131] Comparative Example 3 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene) was dissolved in NMP at a concentration of 3.0% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0132] Reference example 1 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene) was dissolved in NMP at a concentration of 12% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0133] Reference example 2 An electrode-integrated separation membrane for a lithium secondary battery and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the binder solution was applied to the negative electrode active material layer of the negative electrode plate to a thickness of 70 μm using a comma coater.

[0134] Reference example 3 A lithium secondary battery electrode-integrated separation membrane and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a binder solution was used in which poly(vinylidene fluoride-co-hexafluoropropylene) was dissolved in NMP at a concentration of 8% by weight based on the total weight of the solution, instead of the aforementioned binder solution.

[0135] Experimental Example 1 The viscosity of the binder solutions applied to the above examples and comparative examples was measured using a Discovery HR-2 rheometer manufactured by TA Instrument Corporation under conditions of 25°C and a shear rate of 1.0.

[0136] Experimental Example 2 In the binder coating layer and porous layer formation steps according to the above examples and comparative examples, the appearance of the binder coating layer and porous layer was visually observed to confirm the presence or absence of bubbles (O, X).

[0137] Experimental Example 3 The electrode-integrated separation membranes (5 samples each) manufactured in the above examples and comparative examples were subjected to a 180-degree peel strength test using a TA-XT2 plus system from Stable Micro Systems, in accordance with the ASTM D3330 (2018) test method.

[0138] After fixing the sample (electrode-integrated separation membrane) vertically to the ground, a tape (3M Scotch Tape, 18 mm wide) was attached in a U-shape to the porous layer. One end of the tape was placed on the grip of the device and pulled vertically to the ground (measurement speed 300 mm / min, measurement distance 5 cm). The strength of the force applied to the grip was measured when the tape was peeled off at 180 degrees. The above test was performed on five samples, and the average value of the 180-degree peel-off force was calculated.

[0139] Experimental Example 4 The binder coating layer and the porous layer according to the above examples and comparative examples were subjected to an alternating current at a frequency of 0.5 ohms at 200,000 ohms, and their impedance and resistance (ohms) were measured.

[0140] [Table 1]

[0141] Based on the results of the aforementioned experimental example, the manufacturing method according to the above example showed good coating properties without the generation of bubbles in the binder coating layer and porous layer formation steps. Furthermore, the electrode-integrated separation membrane manufactured by the method according to the above example showed high peel strength without an increase in electrical resistance due to the binder coating layer and the porous layer.

[0142] In the manufacturing method described above, a large number of bubbles were generated during the formation steps of the binder coating layer and the porous layer, resulting in degraded coating properties. Furthermore, the electrode-integrated separation membrane manufactured by the method described above had the problem of low peel strength.

[0143] In the manufacturing method described in the above reference example, no bubbles were generated during the formation steps of the binder coating layer and the porous layer, and high peel strength was observed, but there was a problem of a significant increase in electrical resistance.

[0144] Although the present invention has been described above by limited embodiments, it goes without saying that the present invention is not limited thereto, and that a wide range of modifications and variations are possible within the equivalent scope of the technical concept of the present invention and the claims described below by persons with ordinary skill in the art to which the present invention pertains.

Claims

1. The steps include applying a binder solution containing a first polymer binder onto an electrode substrate to form a binder coating layer, and The process includes the step of applying a slurry containing a second polymer binder and inorganic fine particles onto the binder coating layer to form a porous layer; The binder solution has a viscosity of 1000 cP to 9500 cP at 25°C. A method for manufacturing an electrode-integrated separation membrane for lithium secondary batteries.

2. The method for producing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the binder solution has a viscosity of 5500 cP to 9500 cP at 25°C.

3. The first and second polymer binders are, independently of each other, polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-chlorotrifluoroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), spandex, butyl acrylate, polymethyl methacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl acetate, polyimide, polyetherimide, and ethylene vinyl acetate copolymers. A method for producing an electrode-integrated separation membrane for lithium secondary batteries according to claim 1, wherein the compound is one or more compounds selected from the group consisting of polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethylcellulose, cyanoethyl sucrose, pullulan, carboxymethylcellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluororubber.

4. The method for producing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the binder solution contains 3.5% to 7.0% by weight of the first polymer binder based on the total weight of the solution.

5. The method for manufacturing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the binder solution is applied to the electrode substrate to a thickness of 10 μm to 50 μm.

6. The inorganic fine particles are SrTiO ｚ , ｚ , ｘ , ｙ , SnO ２ , CeO ２ , MgO, NiO, CaO, ZnO, ZrO ２ , Y ２ O ３ , Al ２ O ３ , boehmite (AlO(OH)), Al(OH) ３ , TiO ２ , SiC, BaTiO ３ , Pb(Zr,Ti)O ３ , Pb １－ｘ La ｘ Zr １－ｙ Ti ｙ O ３ , Pb(Mg １／３ Nb ２／３ )O ３ - PbTiO ３ , HfO ２ , Li ３ PO ４ , Li ｘ Ti ｙ (PO ４ ) ３ (0 < x < 2, 0 < y < 3), Li ｘ Al ｙ Ti ｚ (PO ４ ) ３ (0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) ｘ O ｙ (0 < x < 4, 0 < y < 13), Li ｘ La ｙ TiO ３ (0 < x < 2, 0 < y < 3), Li ｘ Ge ｙ P ｚ [ S ｗ (0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), Li ｘ N ｙ (0 < x < 4, 0 < y < 2), Li ｘ Si ｙ S ｚ (0 < x < 3, 0 < y < 2, 0 < z < 4), and Li ｘ P ｙ S ｚ A method for manufacturing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein one or more of the following are selected from the group consisting of (0 < x < 3, 0 < y < 3, 0 < z < 7).

7. The method for manufacturing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the inorganic fine particles have a particle size of 0.001 μm to 10 μm.

8. The method for producing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the binder solution and the slurry each independently contain one or more solvents selected from the group consisting of acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, N-methyl-2-pyrrolidone, methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone, dibutyl ether, tetrahydrofuran, cyclohexanone, benzene, fluorobenzene, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, dimethylformamide, 1,3-dioxolane, and sulfolane.

9. The method for manufacturing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the slurry has a solid content of 30% to 80% by weight.

10. The method for manufacturing an electrode-integrated separation membrane for a lithium secondary battery according to claim 1, wherein the electrode substrate includes an electrode active material layer laminated on an electrode current collector layer.

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