Battery separator, electrolyte membrane, battery, method for manufacturing battery separator, and method for manufacturing electrolyte membrane

Abstract

The present invention relates to a battery separator, an electrolyte membrane, a battery, a method for manufacturing a battery separator, and an electrolyte membrane. The battery separator of the present invention can exhibit high liquid electrolyte impregnability. The electrolyte membrane of the present invention can exhibit excellent mechanical stability and thermal properties. The battery of the present invention is safe and can exhibit excellent performance. The method for manufacturing a battery separator of the present invention can improve the liquid electrolyte impregnability of the battery separator. The method for manufacturing an electrolyte membrane of the present invention can enhance the mechanical stability and thermal properties of the electrolyte membrane.

Description

Battery separator, electrolyte membrane, battery, method of manufacturing a battery separator, and method of manufacturing an electrolyte membrane

[0001] This document claims the benefit of the priority date of Application No. 10-2024-0193082 filed with the Korean Intellectual Property Office on December 20, 2024, and incorporates the entire contents thereof by reference.

[0002] The present invention is a battery separator.

[0003] The present invention is an electrolyte membrane.

[0004] The present invention is a battery.

[0005] The present invention is a method for manufacturing a battery separator.

[0006] The present invention is a method for manufacturing an electrolyte membrane.

[0007] Inorganic coated separators are one of the technologies for suppressing the risk of battery ignition associated with the use of liquid electrolytes. Inorganic coated separators may comprise a porous substrate layer and inorganic particles coating the outside thereof. The inorganic particles can form a dense pore structure based on interstitial volume. The pore structure of the separator may vary depending on the amount of liquid electrolyte impregnated.

[0008] Inorganic coated separators exhibit low liquid electrolyte impregnation. Consequently, residual liquid electrolyte can rapidly vaporize. Furthermore, the residual liquid electrolyte may react with the electrodes. The rapid vaporization of the liquid electrolyte reduces battery safety. The adverse reactions of the liquid electrolyte lower battery performance.

[0009] One embodiment (Embodiment) of the present invention is a battery separator comprising: a substrate layer; and a composite layer located on one or both sides of the substrate layer and comprising a binder, a crosslinking agent, and inorganic particles, wherein the binder content (weight%) of the composite layer is in the range of 10 to 40 and the porosity (%) of the composite layer is in the range of 40 to 62.

[0010] The above binder may include a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound.

[0011] The weight average molecular weight (g / mol) of the binder may be in the range of 150,000 to 600,000, and the second unit content (weight%) of the binder may be in the range of 10 to 25.

[0012] The number of crosslinkable functional groups of the above crosslinking agent may be 2 or more.

[0013] The crosslinking agent may include a di(meth)acrylate compound, a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof.

[0014] The above crosslinking agent may include a monomeric compound, a polymeric compound, or a combination thereof.

[0015] The above crosslinking agent is trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, erythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, It may include dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, poly(ethylene oxide-propylene oxide) di(meth)acrylate, polyurethane di(meth)acrylate, polycarbonate di(meth)acrylate, or a combination thereof.

[0016] The above composite layer may contain the binder in a greater weight than the crosslinking agent.

[0017] The above inorganic particles may include a first inorganic particle capable of lithium ion transfer, a second inorganic particle capable of piezoelectricity, a third inorganic particle capable of flame retardancy, or a combination thereof.

[0018] Another embodiment of the present invention is an electrolyte membrane comprising: a substrate layer; and an electrolyte layer located on one or both sides of the substrate layer and comprising a polymer matrix and a liquid electrolyte impregnated in the polymer matrix; wherein the electrolyte membrane exhibits a first decomposition peak and a second decomposition peak, respectively, at a first temperature and a second temperature higher than the first temperature during differential thermal gravimetry (DTG), and wherein the first temperature (°C) is 200 or higher and the second temperature (°C) is within the range of 90 to 150.

[0019] The first temperature (°C) above may be in the range of 200 to 250.

[0020] The polymer matrix may include binder-derived components and crosslinking agent-derived components.

[0021] The above liquid electrolyte may include a non-aqueous solvent and a lithium salt.

[0022] The above electrolyte layer may contain a linear carbonate compound in a larger volume than a cyclic carbonate compound.

[0023] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0024] The above linear carbonate-based compound may be liquid at room temperature.

[0025] The above-mentioned cyclic carbonate compounds may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0026] The above cyclic carbonate compound may be solid at room temperature.

[0027] The volume (volume%) of the linear carbonate-based compound in the above electrolyte layer may be in the range of 55 to 95.

[0028] Another embodiment of the present invention comprises a positive electrode, a negative electrode, and an electrolyte membrane located between the positive electrode and the negative electrode, wherein the electrolyte membrane comprises a substrate layer; and an electrolyte layer located on one or both sides of the substrate layer and comprising a polymer matrix and a liquid electrolyte impregnated in the polymer matrix; wherein the electrolyte membrane exhibits a first decomposition peak and a second decomposition peak, respectively, at a first temperature and a second temperature higher than the first temperature during differential thermal gravitational analysis (DTG), and wherein the first temperature (°C) is 200 or higher and the second temperature (°C) is within the range of 90 to 150.

[0029] Another embodiment of the present invention is a method for manufacturing a battery separator comprising: preparing a slurry comprising a binder, a crosslinking agent, inorganic particles, and a first solvent; manufacturing a coating structure by coating the slurry on one or both sides of a substrate layer; immersing the coating structure in a first bath comprising the first solvent and a second solvent; immersing the coating structure in a second bath comprising the second solvent; and applying light to the coating structure, wherein the binder dissolves better in the first solvent than in the second solvent at room temperature.

[0030] Immersion in the above-mentioned second section may involve immersing the coating structure immersed in the above-mentioned first section into the above-mentioned second section.

[0031] It may further include drying the coating structure immersed in the above Article 2.

[0032] The above light can be applied to the dried coating structure.

[0033] The first solvent above may contain NMP, and the second solvent may contain water.

[0034] Another embodiment of the present invention is a method for manufacturing an electrolyte membrane comprising: preparing a slurry comprising a binder, a crosslinking agent, inorganic particles, and a first solvent; preparing a coating structure by coating the slurry on one or both sides of a substrate layer; immersing the coating structure in a first bath comprising the first solvent and a second solvent; immersing the coating structure in a second bath comprising the second solvent; applying light to the coating structure; and immersing the coating structure in a liquid electrolyte; wherein the binder dissolves better in the first solvent than in the second solvent at room temperature.

[0035] Immersion in the above liquid electrolyte may involve immersing the coating structure, to which light is applied, in the above liquid electrolyte.

[0036] The battery separator of the present invention can exhibit high liquid electrolyte impregnation.

[0037] The electrolyte membrane of the present invention can exhibit excellent mechanical stability and thermal properties.

[0038] The battery of the present invention is safe and can exhibit excellent performance.

[0039] The method for manufacturing a battery separator according to the present invention can increase the liquid electrolyte impregnation of the battery separator.

[0040] The method for manufacturing an electrolyte membrane according to the present invention can improve the mechanical stability and thermal properties of the electrolyte membrane.

[0041] Figure 1 shows the results of the DTG behavior analysis of the example and comparative example.

[0042] This document may use ordinal numbers such as “first” and “second” when referring to multiple components. There is no priority among the components.

[0043] In this document, if a specific commercially available product is used as an ingredient, the characteristics of that ingredient may refer to the characteristics listed in the product's Technical Data Sheet (TDS) or Certification of Analysis (COA).

[0044] In this document, if the physical properties of a specific material vary depending on temperature and pressure, the measurement standards for those properties may be room temperature (25 ℃) and atmospheric pressure (101.325 kPa). This is in accordance with the Standard Ambient Temperature and Pressure (SATP) defined in the CRC Chemical and Physical Handbook.

[0045] In this document, the numerical range “within the range of A to B” means “A or greater and B or less.”

[0046] The numbers mentioned in this document are rounded values. For example, 1.5 is a number within the range of 1.45 to 1.54.

[0047] The present document describes the invention in more detail below.

[0048] One embodiment (Embodiment) of the present invention is a battery separator.

[0049] In this document, a battery may include any element that performs an electrochemical reaction.

[0050] The above battery may refer to any type of primary battery, secondary battery, fuel battery, solar battery, or capacitor, etc. The above battery may refer to a lithium secondary battery. The above lithium secondary battery may include a lithium metal secondary battery, a lithium polymer secondary battery, a lithium ion polymer secondary battery, or a lithium ion secondary battery, etc.

[0051] The battery separator may be located between the electrodes in the battery. The battery separator may be located between the positive and negative electrodes in the battery. The battery separator may prevent physical contact (short circuit) between the positive and negative electrodes in the battery. A charge carrier (e.g., lithium ions) may move through the battery separator between the electrodes.

[0052] The battery separator of the present invention comprises a substrate layer; and a composite layer.

[0053] The above substrate layer can cause a fluid to move from one side of the substrate layer to another side.

[0054] The composite layer is located on one or both sides of the substrate layer. Specifically, the composite layer may be located on a first side of the substrate layer, or on a second side facing the first side. When the composite layer is located on both the first side and the second side, the composition and thickness of each composite layer may be the same or different.

[0055] The above composite layer can provide a path for charge carriers to move to the battery separator.

[0056] The above composite layer includes a binder, a crosslinking agent, and inorganic particles.

[0057] The binder forms a polymer matrix alone or together with the crosslinking agent. The binder may serve as a mechanical support for the polymer matrix.

[0058] The crosslinking agent forms a polymer matrix alone or together with the binder. The crosslinking agent can connect the binders and / or the crosslinking agents in the polymer matrix.

[0059] The above inorganic particles can impart specific properties to the battery separator. For example, the above inorganic particles can impart lithium ion mobility performance to the battery separator, impart piezoelectricity, and / or impart thermal properties (heat resistance, flame retardancy, etc.).

[0060] The above inorganic particles can be dispersed in the polymer matrix.

[0061] The battery separator of the present invention can exhibit high liquid electrolyte impregnation and excellent mechanical and thermal properties by controlling the characteristics of the composite layer.

[0062] The binder content (weight%) of the above composite layer is within the range of 10 to 40.

[0063] The binder content of the composite layer may affect the porosity of the composite layer in conjunction with the inorganic particles and the manufacturing method of the composite layer described below. Additionally, the binder content of the composite layer may affect the physical strength, thermal properties, and electrochemical performance of the battery separator in conjunction with the crosslinking agent. Specifically, when the binder content of the composite layer is within the above range, the structure of the polymer matrix resulting from the crosslinking of the binder and the crosslinking agent can be appropriately realized, and such a structure can improve the physical strength, thermal properties, and electrochemical performance of the composite layer.

[0064] If the binder content (weight%) of the composite layer is less than 10, the cross-linking structure of the polymer matrix and the resulting pore distribution are not sufficiently formed in the composite layer. The insufficient cross-linking structure and lack of porosity degrade the heat resistance, ion conductivity, and long-term durability of the battery separator.

[0065] If the binder content (weight%) of the composite layer exceeds 40, the cross-linking structure of the polymer matrix may not be formed, or the binder may remain in the composite layer without undergoing a cross-linking reaction. The residual binder may interfere with the effect of the cross-linking structure. The residual binder degrades the heat resistance and durability of the battery separator. In addition, the inorganic particle content of the composite layer decreases at this time, which lowers the mechanical or structural stability of the battery separator.

[0066] Preferably, the binder content (weight%) of the composite layer may be 15 or more, 20 or more, or 25 or more. The binder content (weight%) of the composite layer may be 35 or less, 30 or less, or 25 or less.

[0067] The binder content of the above composite layer may refer to the ratio (B / A) of the weight of the binder (B) to the total solid weight (A) of the above composite layer.

[0068] The binder content of the above composite layer can be controlled by the amount of binder in the composition used to form the above composite layer.

[0069] The porosity (%) of the above composite layer is within the range of 40 to 62.

[0070] The porosity of the composite layer can affect the liquid electrolyte impregnation of the battery separator. Liquid electrolyte impregnation can directly affect the safety and performance of the battery. When the porosity of the composite layer is within the above range, the liquid electrolyte impregnation of the battery separator can be maximized, while simultaneously, the structural stability of the battery separator can also be sufficiently ensured.

[0071] If the porosity (%) of the above composite layer is less than 40, the liquid electrolyte cannot be sufficiently impregnated into the battery separator. Insufficient liquid electrolyte impregnation reduces heat resistance, ion conductivity, and long-term durability.

[0072] If the porosity (%) of the above composite layer exceeds 62, the liquid electrolyte is over-impregnated into the battery separator. An excess amount of liquid electrolyte remains in the battery separator. The residual liquid electrolyte is susceptible to thermal stimulation, which reduces heat resistance and long-term durability.

[0073] Preferably, the porosity (%) of the composite layer may be 45 or more, 50 or more, or 55 or more. The porosity (%) of the composite layer may be 61 or less, 60 or less, or 55 or less.

[0074] The porosity (%) of the above composite layer may be the average porosity. The average porosity may refer to the average value based on the number of measurements of the porosity measurements of the above composite layer.

[0075] The porosity of the composite layer may be a value measured based on length. Specifically, the porosity of the composite layer is the loading (g / m²) per unit area of ​​the composition used to form the composite layer. 2), can be calculated by considering the solid density of the above composition. When the composition used to form the above composite layer is referred to as 'Composition A', the porosity (%) of the above composite layer can be defined as "(Coating thickness of Composition A - (Loading per unit area of ​​Composition A) / (Solid density of Composition A)) / (Coating thickness of Composition A) X 100 (%)".

[0076] In addition, the porosity of the above composite layer can be measured, for example, in accordance with ISO 15901-1:2016.

[0077] The manner in which the above composite layer exhibits the aforementioned porosity is not particularly limited. For example, the type and content of each component of the composition used to form the above composite layer, including a binder, a crosslinking agent, and inorganic particles, may affect the porosity. Furthermore, the method of forming the above composite layer, that is, the method of creating the composite layer using the above composition, such as conditions during UV curing, may also affect the porosity of the above composite layer.

[0078] Below, this document describes in more detail other configurations included in the battery separator.

[0079] The above substrate layer may include a polyolefin-based film. Specifically, the above substrate layer may include a porous polyolefin-based film.

[0080] Here, a polyolefin-based porous film refers to a porous film containing a polyolefin-based resin as a main component.

[0081] The above polyolefin-based porous film may contain the polyolefin-based resin in an amount of 50 volume% or more, 90 volume% or more, or 95 volume% or more of the total material constituting the polyolefin-based porous film.

[0082] The weight average molecular weight of the component included in the above polyolefin resin is 3×10 5 Up to 15×10 6It may be possible. If the weight average molecular weight of the component included in the above polyolefin resin is 1 million or more, the strength of the separator including the above polyolefin porous film may be improved.

[0083] The above polyolefin resin may include a thermoplastic resin. The above thermoplastic resin may include a homopolymer (e.g., polyethylene, polypropylene, polybutene) or copolymer (e.g., ethylene-propylene copolymer) formed by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and 1-hexene.

[0084] The above polyolefin-based porous film may be a layer comprising only these polyolefin-based resins, or a layer comprising two or more of these polyolefin-based resins. Among these, polyethylene and high molecular weight polyethylene having ethylene as a main backbone can stop (shut down) the flow of excessive current at a lower temperature. In addition, the polyolefin-based porous film may additionally include components other than polyolefin-based resins that do not impair the function of the film.

[0085] The binder can form the framework of the polymer matrix. The binder has appropriate crystallinity to increase the ion conductivity of the battery separator. The polar portion of the binder can bond with the crosslinking agent. The binder can form a crosslinked structure with the crosslinking agent.

[0086] The above binder may include a fluorine-based binder. The above fluorine-based binder may refer to a binder whose constituent unit contains fluorine as part or all. The above fluorine-based binder may include a PVDF-based binder.

[0087] The above binder is a battery separator comprising a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound.

[0088] The above PVDF-based binder may be a homopolymer or copolymer comprising a polymerization unit derived from vinylidene fluoride. The above fluorine-based binder may comprise a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound. The above PVDF-based binder may be a block copolymer or a random copolymer comprising the first unit and the second unit. Preferably, the above PVDF-based binder may be a random copolymer comprising the first unit and the second unit.

[0089] The above fluorine-containing alkyl vinyl compound is C n H (2n+1-y) F y It may mean a compound in which at least one fluorine-containing alkyl group represented by is bonded to a vinyl group. However, vinylidene fluoride is excluded.

[0090] The fluorine-containing alkyl vinyl compound may include one or more selected from the group consisting of vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, and hexafluoropropylene. Preferably, the fluorine-containing alkyl vinyl compound may include one or more selected from the group consisting of hexafluoropropylene, tetrafluoroethylene, and chlorotrifluoroethylene. More preferably, the fluorine-containing alkyl vinyl compound may include hexafluoropropylene.

[0091] The second unit content of the above-mentioned fluorine-based binder can be adjusted. The second unit content of the above-mentioned fluorine-based binder may affect the crystallinity of the above-mentioned fluorine-based binder, the ionic conductivity of the above-mentioned battery separator, and the mechanical strength.

[0092] The second unit content (weight%) of the above fluorine-based binder may be in the range of 10 to 25. Preferably, the second unit content (weight%) of the above fluorine-based binder may be 15 or more, 16 or more, 17 or more, or 18 or more. The second unit content (weight%) of the above fluorine-based binder may be 23 or less, 21 or less, 20 or less, or 19 or less.

[0093] The first and second unit contents of the above fluorine-based binder are relative to the above fluorine-based binder 19 It can be measured by F-NMR analysis.

[0094] The weight-average molecular weight of the fluorine-based binder can also be controlled. The weight-average molecular weight (g / mol) of the fluorine-based binder may be in the range of 150,000 to 600,000. Preferably, the weight-average molecular weight (g / mol) of the fluorine-based binder may be 200,000 or more, 250,000 or more, 300,000 or more, or 350,000 or more. The weight-average molecular weight (g / mol) of the fluorine-based binder may be 550,000 or less, 500,000 or less, 450,000 or less, 400,000 or less, or 350,000 or less.

[0095] The weight average molecular weight of the above fluorine-based binder can be measured by gel permeation chromatography.

[0096] The melting point of the above fluorine-based binder can also be controlled. The melting point (°C) of the above fluorine-based binder may be in the range of 100 to 140. Preferably, the melting point (°C) of the above fluorine-based binder may be 110 or higher, or 115 or higher. The melting point (°C) of the above fluorine-based binder may be 135 or lower, 130 or lower, or 125 or lower.

[0097] The number of crosslinkable functional groups of the crosslinking agent may be two or more. Here, the number of crosslinkable functional groups of the crosslinking agent may refer to the number of crosslinkable functional groups per molecule of the crosslinking agent. The crosslinkable functional groups may be functional groups that act to connect binders and / or crosslinking agents in the polymer matrix.

[0098] Preferably, the number of crosslinkable functional groups of the crosslinking agent may be 3 or more, or 4 or more. The number of crosslinkable functional groups of the crosslinking agent may be 6 or less, or 5 or less.

[0099] The above-mentioned crosslinking functional group may include a photoreactive functional group. Specifically, the above-mentioned crosslinking functional group may include a (meth)acryloyl group as a photoreactive functional group. The above-mentioned crosslinking agent may include a polyfunctional (meth)acrylate-based compound. Preferably, from the viewpoint of preventing deterioration of electrochemical properties due to the rate of the crosslinking reaction and the stiffness of the polymer network, the above-mentioned crosslinking functional group may include an acryloyl group as a photoreactive functional group.

[0100] Accordingly, the crosslinking agent may include a di(meth)acrylate compound, a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof.

[0101] Specifically, the crosslinking agent may include a diacrylate compound, a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, a hexaacrylate compound, or a combination thereof.

[0102] More specifically, the crosslinking agent may include a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, or a combination thereof.

[0103] More specifically, the crosslinking agent may include a triacrylate-based compound.

[0104] The above-mentioned crosslinking agent may include a monomeric compound, a polymeric compound, or a combination thereof. The above-mentioned monomeric crosslinking agent may mean that the remaining moiety, excluding the crosslinking functional group, is of monomer origin. The above-mentioned polymeric crosslinking agent may mean that the remaining moiety, excluding the crosslinking functional group, is of polymer origin.

[0105] Specifically, the crosslinking agent may include a monomeric compound.

[0106] The above crosslinking agent is trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, erythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, It may include dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, poly(ethylene oxide-propylene oxide) di(meth)acrylate, polyurethane di(meth)acrylate, polycarbonate di(meth)acrylate, or a combination thereof.

[0107] Specifically, the crosslinking agent is trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, erythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, It may include dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, or a combination thereof.

[0108] More specifically, the crosslinking agent is trimethylolethane triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, glycerol triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, erythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated dipentaerythritol pentaacrylate, sorbitol pentaacrylate, dipentaerythritol It may include hexaacrylate, ethoxylated dipentaerythritol hexaacrylate, sorbitol hexaacrylate, or a combination thereof.

[0109] More specifically, the crosslinking agent may include trimethylolethane triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, glycerol triacrylate, ethoxylated glycerol triacrylate, propoxylated glycerol triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, or a combination thereof.

[0110] Not only the porosity of the composite layer, but also the size of the pores contained in the composite layer can be controlled. The average size (㎛) of the pores in the composite layer may be in the range of 0.1 to 1.

[0111] Preferably, the average size (μm) of the pores in the composite layer may be 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more. The average size (μm) of the pores in the composite layer may be 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less.

[0112] In terms of ensuring the heat resistance of the battery separator and delaying its vaporization even after impregnation with the liquid electrolyte, the inorganic particles may be included in the composite layer in greater quantities than the binder. That is, among the inorganic particles, binder, and crosslinking agent included in the composite layer, excluding the crosslinking agent, the inorganic particles may be included in the composite layer in greater quantities than the binder. Specifically, the composite layer may contain the inorganic particles by a greater weight than the binder.

[0113] The inorganic particle content of the above composite layer (parts by weight, relative to 100 parts by weight of the binder) may be in the range of 150 to 1000.

[0114] Preferably, the inorganic particle content (parts by weight, relative to 100 parts by weight of the binder) of the composite layer may be 200 or more, 217 or more, 250 or more, 300 or more, 325 or more, 350 or more, 400 or more, 450 or more, or 500 or more. The inorganic particle content (parts by weight, relative to 100 parts by weight of the binder) of the composite layer may be 950 or less, 900 or less, 850 or less, 800 or less, 750 or less, 700 or less, 650 or less, 600 or less, 550 or less, or 500 or less.

[0115] The content of the binder and the crosslinking agent in the composite layer can also be controlled in terms of forming an appropriate crosslinking structure within the composite layer.

[0116] That is, among the inorganic particles, binder, and crosslinking agent included in the composite layer, excluding the inorganic particles, the binder may be included in the composite layer in a greater amount than the crosslinking agent. Specifically, the composite layer may contain the inorganic particles in a greater weight than the binder.

[0117] The crosslinking agent content of the above composite layer (parts by weight, relative to 100 parts by weight of the binder) may be in the range of 1 to 99.

[0118] Preferably, the crosslinking agent content (parts by weight, relative to 100 parts by weight of the binder) of the composite layer may be 10 or more, 16 or more, 20 or more, 30 or more, 40 or more, or 50 or more. The crosslinking agent content (parts by weight, relative to 100 parts by weight of the binder) of the composite layer may be 90 or less, 80 or less, 74 or less, 70 or less, 60 or less, or 50 or less.

[0119] The type of the above-mentioned inorganic particles may vary depending on the characteristics that the above-mentioned inorganic particles impart to the battery separator.

[0120] The above inorganic particles may include a first inorganic particle capable of lithium ion transfer, a second inorganic particle capable of piezoelectricity, a third inorganic particle capable of flame retardancy, or a combination thereof. Preferably, the inorganic particles may include a first inorganic particle capable of lithium ion transfer, a third inorganic particle capable of flame retardancy, or a combination thereof. More preferably, the inorganic particles may include a third inorganic particle capable of flame retardancy.

[0121] Lithium ion-transporting inorganic particles contain lithium but can perform the function of transporting lithium ions without storing lithium. There may be a type of defect inside the lithium ion-transporting inorganic particles. Charge carriers, such as lithium ions, can move by utilizing said defects. Therefore, the lithium ion-transporting inorganic particles can improve the lithium ion conductivity within the battery. As a result, the performance of the battery can also be improved.

[0122] The above first inorganic particle is 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), Li x La y TiO3(0 <x<2, 0<y<3), Li 6+x La3Zr 2-y M y O 12-z (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2), or a combination thereof may be included.

[0123] Piezoelectric inorganic particles are materials that exhibit different electrical conductivity depending on the applied pressure. Specifically, piezoelectric inorganic particles are insulators at atmospheric pressure and become electrical conductors when a certain pressure is applied. The dielectric constant of the piezoelectric inorganic particles is relatively high. The dielectric constant of the piezoelectric inorganic particles may be 100 or higher. When the piezoelectric inorganic particles are stretched or compressed by a certain pressure, an electric charge may be generated. One side of the piezoelectric inorganic particles may be positively charged and the other side negatively charged, thereby creating a potential difference within the piezoelectric inorganic particles. If a short circuit occurs inside the anode and cathode due to an external impact, the piezoelectric inorganic particles placed in the separator can prevent physical contact between the anode and cathode. This potential difference can apply a microcurrent between the anode and cathode. This microcurrent can improve the safety of the battery by gradually lowering the voltage of the battery in the event of a short circuit.

[0124] The above second inorganic particles are BaTiO3, BaSO4, 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 It may include )O3-PbTiO3(PMN-PT), HfO2(Hafnia), or a combination thereof.

[0125] Flame-retardant inorganic particles can add flame-retardant properties to battery separators and prevent a rapid rise in the internal temperature of the battery.

[0126] The third inorganic particle may include SrTiO3, SnO2, CeO2, MgO, Mg(OH)2, NiO, CaO, ZnO, Zn2SnO4, ZnSnO3, ZnSn(OH)6, ZrO2, Y2O3, Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof. Preferably, the third inorganic particle may include ZrO2, Y2O3, Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof. More preferably, the third inorganic particle may include Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof.

[0127] The battery separator of the present invention can further control the characteristics of the inorganic particles.

[0128] Specifically, the above-mentioned inorganic particles may include flame-retardant third inorganic particles. In this case, the characteristics of the inorganic particles can be further controlled to increase electrolyte impregnation while simultaneously maintaining thermal stability.

[0129] The D50 (nm) of the above inorganic particle may be in the range of 100 to 1000. The D50 (nm) of the above inorganic particle may be 150 or more, 200 or more, 250 or more, 300 or more, 350 or more, or 400 or more. The D50 (nm) of the above inorganic particle may be 900 or less, 800 or less, 700 or less, 600 or less, 500 or less, or 400 or less.

[0130] BET specific surface area (m²) of the above inorganic particles 2 The value ( / g) may be in the range of 5 to 20. The BET specific surface area (m²) of the inorganic particles 2 The value ( / g) may be 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 12 or more. The BET specific surface area (m²) of the inorganic particle is 2 / g) may be 18 or less, 16 or less, 15 or less, 14 or less, or 12 or less.

[0131] The above composite layer may further include an initiator.

[0132] When a predetermined stimulus is applied, the initiator can initiate a reaction in which the binder forms a polymer matrix.

[0133] The above initiator may include a thermal polymerization initiator, a photopolymerization initiator, or a combination thereof. Preferably, the initiator may include a photopolymerization initiator.

[0134] The above photopolymerization initiator may include a short-wavelength photopolymerization initiator, a long-wavelength photopolymerization initiator, or a combination thereof. Preferably, the photopolymerization initiator may include a long-wavelength photopolymerization initiator.

[0135] The above short-wavelength photopolymerization initiator may include IRGACURE 127 (1,1'-(Methylene-di-4,1-phenylene)bis[2-hydroxy-2-methyl-1-propanone]), IRGACURE 1173 (2-Hydroxy-2-methylpropiophenone, HMPP), DMPA (2,2-dimethoxy-2-phenylacetonephenone), HOMPP (2-hydroxy-2-methylpropipphenone), LAP (Lithium phenyl-2,4,6-trimethylbenzoylphosphinate), or a combination thereof.

[0136] The above long-wavelength photopolymerization initiator may include one or more selected from the group consisting of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide and Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate. Preferably, the above long-wavelength photopolymerization initiator may include Ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L).

[0137] The initiator content of the composite layer can also be appropriately controlled in order to appropriately control the crosslinking reaction between the binder and the crosslinking agent. The composite layer may contain the crosslinking agent in a greater weight than the initiator.

[0138] The initiator content of the composite layer (parts by weight, relative to 100 parts by weight of the crosslinking agent) may be in the range of 1 to 10. Preferably, the initiator content of the composite layer (parts by weight, relative to 100 parts by weight of the crosslinking agent) may be 1.1 or more, 1.3 or more, 1.5 or more, 1.7 or more, 1.9 or more, or 2.0 or more. The initiator content of the composite layer (parts by weight, relative to 100 parts by weight of the crosslinking agent) may be 9 or less, 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, 3 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, or 2.1 or less.

[0139] Another embodiment of the present invention is an electrolyte membrane.

[0140] Specifically, the electrolyte membrane of the present invention can be manufactured by immersing the aforementioned battery separator in a liquid electrolyte. The composite layer of the aforementioned battery separator can exhibit electrolyte performance when impregnated with a liquid electrolyte. This can be represented as an electrolyte layer.

[0141] In addition, while describing the electrolyte membrane of this embodiment, the description of the battery separator of the aforementioned embodiment may be applied as is.

[0142] The electrolyte membrane of this embodiment includes a substrate layer; and an electrolyte layer.

[0143] The above electrolyte layer can provide a path for charge carriers to move in the above electrolyte membrane.

[0144] The electrolyte layer is located on one or both sides of the substrate layer. Specifically, the electrolyte layer may be located on a first side of the substrate layer, or on a second side facing the first side. When the electrolyte layer is located on both the first side and the second side, the composition and thickness of each electrolyte layer may be the same or different.

[0145] The above electrolyte layer includes a gel polymer electrolyte.

[0146] In this document, the gel polymer electrolyte is an electrolyte in the gel phase. The gel polymer electrolyte comprises a polymer matrix and a liquid electrolyte. The liquid electrolyte may be impregnated into the polymer matrix. Here, the polymer matrix may physically support the gel polymer electrolyte. The liquid electrolyte may impart ionic conductivity to the gel polymer electrolyte.

[0147] This electrolyte membrane exhibits specific behavior during differential thermal gravimetry. Specifically, the electrolyte membrane exhibits peaks at two different temperatures during differential thermal gravimetry (DTG). The peaks exhibited by the electrolyte membrane represent the decomposition peaks of the electrolyte membrane. These peaks may represent local minima of the temperature versus weight change rate curve plotted during DTG of the electrolyte membrane.

[0148] Specifically, the electrolyte membrane exhibits a first decomposition peak at a first temperature (T1) during DTG and a second decomposition peak at a second temperature (T2) higher than the first temperature. The fact that the electrolyte membrane exhibits at least two decomposition peaks during DTG means that the electrolyte membrane decomposes in at least two temperature ranges. Furthermore, the fact that there are two or more temperature ranges in which decomposition peaks appear means that the electrolyte membrane contains two or more materials with different thermal properties.

[0149] The present invention controls the first temperature and the second temperature. Through this, the electrolyte membrane of the present invention can simultaneously exhibit a suitable liquid electrolyte impregnation amount, increased ion conductivity, and heat resistance.

[0150] The decomposition peak of the electrolyte membrane and the temperature at which the decomposition peak appears are determined according to the thermal characteristics of the components included in the electrolyte membrane. Specifically, the number of decomposition peaks and the temperature at which the peaks appear during DTG of the electrolyte membrane can be determined by the number and type of components included in the electrolyte membrane.

[0151] The above second temperature (°C) is 200 or higher.

[0152] The fact that the second temperature (°C) is 200°C or higher means that among the at least two decomposition peaks appearing during DTG of the electrolyte membrane, the peak appearing at the higher temperature is observed at the said temperature. Additionally, this may mean that the electrolyte layer of the electrolyte membrane has impregnated an appropriate amount of liquid electrolyte to reduce the amount of residual liquid electrolyte. Furthermore, this may mean that the liquid electrolyte contains a significant amount of a non-aqueous solvent with a boiling point higher than the said second temperature. This also means that the electrolyte membrane exhibits excellent heat resistance.

[0153] If the second temperature (°C) is less than 200°C, it means that the electrolyte membrane is thermally decomposed at that low temperature. This means that the amount of liquid electrolyte remaining in the electrolyte membrane is large.

[0154] Preferably, the second temperature (°C) may be 205 or higher, 210 or higher, 215 or higher, 217 or higher, 220 or higher, or 225 or higher. The second temperature (°C) may be 250 or lower, 245 or lower, 240 or lower, 235 or lower, 230 or lower, or 225 or lower.

[0155] The first temperature (°C) above is within the range of 90 to 150.

[0156] The first temperature and the second temperature mentioned above may be derived from the composition of the liquid electrolyte and the thermal properties of the polymer matrix, etc. Accordingly, the first temperature may also impart an appropriate amount of the liquid electrolyte to the polymer matrix and reduce the amount of residual liquid electrolyte in the electrolyte membrane. Furthermore, this may imply that the liquid electrolyte contains an appropriate amount of a non-aqueous solvent having a boiling point similar to that of the first temperature. Accordingly, the electrolyte membrane exhibits excellent heat resistance.

[0157] Preferably, the first temperature (°C) may be 95 or higher, 100 or higher, 105 or higher, 110 or higher, 115 or higher, or 120 or higher. The first temperature (°C) may be 145 or lower, 140 or lower, 135 or lower, 130 or lower, 125 or lower, or 120 or lower.

[0158] The second temperature and the first temperature may be more significant when the ratio of the intensity of the first decomposition peak and the intensity of the second decomposition peak is within a specific range. The intensity of each decomposition peak may be related to the amount of decomposition of the component decomposed at each decomposition peak. That is, the ratio may be determined according to the composition of the component contained in the electrolyte layer.

[0159] In addition, the DTG behavior of the battery separator may vary depending on the method of manufacturing the above electrolyte membrane, specifically, the method of forming the polymer matrix and impregnating the liquid electrolyte.

[0160] The ratio of the intensity of the first decomposition peak and the intensity of the second decomposition peak may be a numerical value reflecting the composition of the component included in the liquid electrolyte. The ratio (IP2 / IP1) of the intensity of the first decomposition peak (IP1) and the intensity of the second decomposition peak (IP2) may be, for example, 0.5 or higher. The ratio (IP2 / IP1) may be 0.55 or higher, 0.6 or higher, 0.65 or higher, or 0.7 or higher. The ratio may be 10 or lower, 9 or lower, 8 or lower, 7 or lower, 6 or lower, 5 or lower, 4 or lower, 3 or lower, 2 or lower, 1 or lower, 0.9 or lower, or 0.85 or lower.

[0161] The composition of the electrolyte layer in the electrolyte membrane of the present invention can be controlled. This allows the electrolyte membrane to exhibit specific thermal behavior. Accordingly, the electrolyte membrane can simultaneously exhibit a suitable liquid electrolyte impregnation amount, high ion conductivity, heat resistance, and long-term durability.

[0162] The polymer matrix described above may be formed by the reaction of a binder and a crosslinking agent included in the aforementioned composite layer. That is, the polymer matrix may include a binder-derived component and a crosslinking agent-derived component.

[0163] As described above, the composite layer may further include an initiator. Therefore, the polymer matrix may further include an initiator-derived component.

[0164] The above liquid electrolyte may include a non-aqueous solvent and a lithium salt. The lithium salt may be dissolved in the non-aqueous solvent.

[0165] The decomposition peak of the electrolyte membrane and the temperature at which this decomposition peak appears may be determined according to the thermal characteristics of the components included in the electrolyte membrane, specifically the electrolyte layer. Specifically, the number of decomposition peaks of the electrolyte membrane and the temperature at which the decomposition peak appears may be determined by the number of non-aqueous solvent species included in the liquid electrolyte. The liquid electrolyte may include two or more types of non-aqueous solvents. The liquid electrolyte may include two or more types of non-aqueous solvents with different boiling points. This may affect the DTG results of the electrolyte membrane.

[0166] The first temperature and the second temperature, the intensity of the first decomposition peak, and the intensity of the second decomposition peak can be determined by the composition of the liquid electrolyte impregnated in the polymer matrix. Specifically, the type of non-aqueous solvent included in the liquid electrolyte may affect the thermal behavior of the electrolyte membrane.

[0167] The above-mentioned non-aqueous solvent may refer to an organic solvent that does not contain water or contains a trace amount of water. The above-mentioned non-aqueous solvent may include carbonate compounds, ether compounds, ester compounds, compounds containing polar functional groups, or mixtures thereof. Preferably, the above-mentioned non-aqueous solvent may include carbonate compounds.

[0168] The above ether-based compound may include dimethoxyethane, diethoxyethane, tetrahydrofuran, or a combination thereof.

[0169] The above ester compound may include N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (γ-butyrolactone), or a combination thereof.

[0170] The above-mentioned polar functional group-containing compound may include dimethyl sulfoxide, acetonitrile, or a combination thereof.

[0171] The above carbonate-based compound may include a linear carbonate-based compound, a cyclic carbonate-based compound, or a combination thereof. Preferably, the carbonate-based compound may include a linear carbonate-based compound and a cyclic carbonate-based compound.

[0172] The above electrolyte layer may contain a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound. In this case, the miscibility of the binder with respect to the liquid electrolyte is increased, and an abnormal increase in viscosity of the electrolyte layer can be prevented.

[0173] In this document, linear carbonate compounds refer to open double esters of carbonic acid. Specifically, linear carbonate compounds include structures in which the two hydroxyl groups of carbonic acid are esterified to different alcohols, and the entire molecule does not form a ring.

[0174] In this document, cyclic carbonate compounds refer to internal esters in which the -O-CO-O- backbone of carbonate groups is contained within a ring structure. Specifically, cyclic carbonate compounds include a structure in which the two ends of two hydroxyl groups within a molecule form ester bonds with the same carbonate group, thereby containing the -O-CO-O- backbone within a ring.

[0175] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0176] Specifically, the linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0177] More specifically, the linear carbonate-based compound may include ethylmethyl carbonate.

[0178] The above linear carbonate-based compound may be liquid at room temperature.

[0179] The above-mentioned cyclic carbonate compounds may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0180] Specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0181] More specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

[0182] From the perspective of the miscibility of the aforementioned binder and liquid electrolyte, the control of the viscosity of the electrolyte layer, and the safety of the battery, it may be desirable for the phases of the linear carbonate-based compound and the cyclic carbonate-based compound to be combined differently.

[0183] The above cyclic carbonate-based compound may be solid at room temperature. Specifically, the above cyclic carbonate-based compound may include ethylene carbonate.

[0184] The amount of the above-mentioned linear carbonate compounds and cyclic carbonate compounds can also be appropriately controlled within a range that satisfies the above conditions.

[0185] The volume (volume%) of the linear carbonate-based compound in the above electrolyte layer may be in the range of 55 to 95.

[0186] Preferably, the volume (volume%) of the linear carbonate-based compound in the electrolyte layer may be 60 or more, 65 or more, or 70 or more. The volume (volume%) of the linear carbonate-based compound in the electrolyte layer may be 90 or less, 85 or less, 80 or less, or 75 or less.

[0187] The volume (volume%) of the cyclic carbonate-based compound in the electrolyte layer may be in the range of 5 to 45. Preferably, the volume (volume%) of the cyclic carbonate-based compound in the electrolyte layer may be 10 or more, 15 or more, 20 or more, or 25 or more. The volume (volume%) of the cyclic carbonate-based compound in the electrolyte layer may be 40 or less, 35 or less, or 30 or less.

[0188] The above lithium salt may be soluble in the above non-aqueous solvent. The above lithium salt may refer to a material that decomposes into lithium cations and anions upon dissociation.

[0189] The lithium salt may include LiPF6, LiBF4, LiCl, LiBr, LiI, LiClO4, LiAsF6, LiCH3CO2, LiCF3SO3, LiN(CF3SO2)2, LiN(FSO2)2, LiC(CF2SO2)3, or a combination thereof. Preferably, the lithium salt may include LiPF6.

[0190] The above liquid electrolyte may further include additives.

[0191] The above additive may refer to a substance applied in small amounts to a liquid electrolyte for the purpose of stabilizing the electrode interface, improving electrochemical stability, controlling conductivity characteristics, improving temperature characteristics, suppressing gas generation, etc.

[0192] The above additive may include vinylene carbonate, 1,3-propane sulfone, 1,3-propene sulfone, lithium difluorophosphate, lithium tetrafluoro(oxaleto)phosphate, lithium bis(fluorosulfonyl)imide, fluoroethylene carbonate, vinyl ethylene carbonate, or a combination thereof. Preferably, the above additive may include vinylene carbonate.

[0193] Since the liquid electrolyte is impregnated into the binder or the polymer matrix formed by the binder in the electrolyte layer, the thickness of the electrolyte layer may generally be thick. Specifically, the electrolyte layer may be thicker than the substrate layer.

[0194] Another embodiment of the present invention is a battery.

[0195] The battery may include a first electrode, a second electrode, a separator, and an electrolyte. The separator may be disposed between the first electrode and the second electrode. The polarity of the first electrode may be opposite to the polarity of the second electrode. If the first electrode is a positive electrode (negative electrode), the second electrode may be a negative electrode (positive electrode).

[0196] The system comprising the separator and electrolyte of the above-described battery may be the electrolyte membrane of the present invention. Accordingly, the description regarding the separator and electrolyte in the description of the battery may be entirely replaced by the aforementioned electrolyte membrane.

[0197] The positive electrode may be an electrode that undergoes a reduction reaction during discharge. The negative electrode may be an electrode that undergoes an oxidation reaction during discharge.

[0198] The electrode of the above battery may include an electrode active material attached to an electrode current collector. Specifically, the electrode may include an electrode current collector and an electrode active material layer disposed on one or both sides of the electrode current collector and comprising an electrode active material.

[0199] Among the electrode active materials, the positive electrode active material may include a lithium intercalation material. The lithium intercalation material may include a lithium transition metal oxide. The lithium intercalation material may include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide and lithium iron oxide, lithium nickel-manganese oxide, lithium nickel-cobalt oxide, lithium nickel-manganese-cobalt oxide, or a combination thereof. Preferably, the positive electrode active material may include lithium nickel-manganese-cobalt oxide.

[0200] Among the above electrode active materials, the negative electrode active material may include a lithium adsorption material. The lithium adsorption material may include a lithium-based metal including lithium metal and lithium alloy; a carbon-based compound including carbon, petroleum coke, activated carbon, and graphite; or a combination thereof.

[0201] The anode current collector may be a foil of a metal comprising aluminum, nickel, or a combination thereof. Preferably, the anode current collector may be an aluminum foil.

[0202] The above-mentioned negative current collector may be a foil of a metal comprising copper, gold, nickel, or a combination thereof. Preferably, the above-mentioned negative current collector may be a copper foil.

[0203] Another embodiment of the present invention is a method for manufacturing a battery separator.

[0204] The above manufacturing method can manufacture the battery separator by forming a composite layer on one or both sides of the substrate layer.

[0205] The above manufacturing method includes preparing a slurry.

[0206] The above slurry comprises a binder, a crosslinking agent, inorganic particles, and a first solvent.

[0207] The above slurry can be directly manufactured or obtained as a product designed and manufactured with the corresponding composition and applied to the present invention.

[0208] This document describes the above binder, crosslinking agent, and inorganic particles, and the same content mentioned in the above battery separator can be applied.

[0209] The above inorganic particles can be dispersed in the first solvent.

[0210] The above slurry may contain the above inorganic particles in greater weight than the binder.

[0211] The above inorganic particles can be dispersed in the first solvent. The binder can be dissolved in the first solvent.

[0212] The method for manufacturing a battery separator according to the present invention comprises coating the slurry on one or both sides of a substrate layer to manufacture a coating structure. The coating structure is a structure comprising a substrate layer and a slurry applied thereto.

[0213] The method for manufacturing a battery separator according to the present invention immerses the coating structure in a specific order in drums of different compositions. As a result, the method of the present invention can manufacture a battery separator capable of simultaneously exhibiting a suitable liquid electrolyte impregnation amount, high ion conductivity, and heat resistance.

[0214] The method for manufacturing a battery separator of the present invention may include immersing the coating structure in a first tank and immersing the coating structure in a second tank.

[0215] The method for manufacturing a battery separator according to the present invention may immerse the coating structure in a first tank, remove the coating structure from the first tank, and then immerse the removed coating structure in a second tank. Immersion in the second tank may involve immersing the coating structure immersed in the first tank into the second tank.

[0216] The method for manufacturing a battery separator of the present invention further comprises applying light to the coating structure. Specifically, the light may be ultraviolet light. Applying light to the coating structure may form a cross-linking structure between the binder and the cross-linking agent.

[0217] The method for manufacturing a battery separator according to the present invention may further include drying the coating structure immersed in the second step. During drying, a porous layer may be formed on one or both sides of the substrate layer.

[0218] The method for manufacturing a battery separator of the present invention may include drying the coating structure before applying light to the coating structure. That is, the method for manufacturing a battery separator of the present invention may remove the coating structure immersed in the second step, dry it, and then apply light to the dried coating structure.

[0219] The method for manufacturing a battery separator according to the present invention configures the types of solvents included in the first and second sections differently. The first section includes a first solvent and a second solvent. The second section includes the second solvent. Specifically, the second section may be composed of the second solvent.

[0220] The first solvent and the second solvent may contain different types of compounds. For example, the criterion for distinguishing the first solvent and the second solvent is the solubility of the binder in each of the solvents. Specifically, the solubility of the binder in the first solvent is higher than the solubility of the binder in the second solvent. More specifically, the binder dissolves better in the first solvent than in the second solvent at room temperature.

[0221] The above Article 1 may include specific components as a first solvent and a second solvent. The first solvent may include NMP (N-methyl-2-pyrrolidone). The second solvent may include water. In this case, the above Article 2 may consist of water.

[0222] The drying, holding temperature and immersion time of the first and second steps, etc., may vary depending on the composition of the slurry and the ratio of the second solvent of the first step, etc. For example, the solid content (weight%) of the slurry may be in the range of 10 to 50. The ratio of the second solvent of the first step (volume%, based on the total volume of the first solvent and the second solvent) may be in the range of 60 to 80.

[0223] Another embodiment of the present invention is a method for manufacturing an electrolyte membrane.

[0224] The above method for manufacturing the electrolyte membrane further includes impregnating the polymer matrix of the composite layer of the battery separator described above with a liquid electrolyte. That is, the method for manufacturing the electrolyte membrane of the present invention may further include immersing the product of the battery separator manufacturing method of the above-described embodiment in a liquid electrolyte.

[0225] That is, the method for manufacturing an electrolyte membrane of the present invention comprises: preparing a slurry comprising a binder, a crosslinking agent, inorganic particles, and a first solvent; preparing a coating structure by coating the slurry on one or both sides of a substrate layer; immersing the coating structure in a first bath comprising the first solvent and a second solvent; immersing the coating structure in a second bath comprising the second solvent; applying light to the coating structure; and immersing the coating structure in a liquid electrolyte.

[0226] Immersion in the above liquid electrolyte may involve immersing the coating structure immersed in Article 2 into the liquid electrolyte. The liquid electrolyte may impregnate the polymer matrix containing the composite layer. As a result, an electrolyte film comprising an electrolyte layer located on one or both sides of the substrate layer may be manufactured.

[0227] Here, immersion in the liquid electrolyte may involve immersing the coating structure irradiated with light into the liquid electrolyte. Specifically, immersion in the liquid electrolyte may involve drying the coating structure immersed in the second step, applying light to the dried coating structure, and then immersing the coating structure to which light has been applied into the liquid electrolyte.

[0228] The present invention is described in more detail below through examples and comparative examples. However, the present invention is not limited to the examples.

[0229] [Preparation Example]

[0230] Example 1. Battery separator and electrolyte membrane

[0231] The battery separator and electrolyte membrane were manufactured according to the following process.

[0232] (1) 30 g of binder, 4.9 g of crosslinking agent, 0.1 g of photopolymerization initiator, and 65 g of inorganic particles were mixed with NMP (N-methyl-2-pyrrolidone) to obtain 2.30 g / cm³ 3Prepare a density slurry. The binder is Arkema's Kynar 2501-20 (PVDF-HFP; weight average molecular weight: 350,000 g / mol; HFP substitution rate: 18.6 wt%). The crosslinking agent is Miwon Specialty Chemical's M340 (Pentaerythritol Triacrylate; PETA). The photopolymerization initiator is IGM's Omnirad TPO-L (Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate). The inorganic particle is Sasol's D60 (Boehmite; D50: 400 nm; BET: 10–12 m 2 / g) is.

[0233] (2) To manufacture a coating structure by coating the above slurry on both sides of the substrate layer with a thickness of 10 μm per layer. The substrate layer is Horizon’s HK09G (PE film, thickness: 9 μm).

[0234] (3) Immerse the coating structure in the first tank. The first tank contains 40 volume% NMP and 60 volume% water. The temperature of the first tank is 20 ℃. The immersion time is 40 seconds.

[0235] (4) After removing the coating structure from the first step, immerse it in the second step. The second step contains 100 volume% of water. The temperature of the second step is 20°C. The immersion time is 60 seconds.

[0236] (5) After removing the coating structure from Article 2 above, dry it in a vacuum oven to form a composite layer located on both sides of the substrate layer. The drying temperature is 80°C. The drying time is 2 minutes. The average porosity per layer of the composite layer is 60%.

[0237] (6) Apply UV light to the composite layer to manufacture a battery separator in which a cross-linked structure of the polymer matrix within the composite layer is formed.

[0238] (7) Prepare an electrolyte membrane by immersing the battery separator in a liquid electrolyte. The liquid electrolyte is a non-aqueous solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7, in which 1 M concentration of LiPF6 is dissolved and 2% of the total weight of vinylene carbonate (VC) is added.

[0239] Example 2. Battery separator and electrolyte membrane

[0240] In (1) above, 30 g of binder, 4.9 g of crosslinking agent, 0.1 g of photopolymerization initiator, and 65 g of inorganic particles were mixed with NMP (N-methyl-2-pyrrolidone) to obtain 2.30 g / cm² 3 A battery separator and an electrolyte membrane were prepared by repeating the same process as in Example 1, except for preparing a density slurry. In (5) above, a composite layer was formed located on both sides of the substrate layer. The average porosity per layer of the composite layer is 50%.

[0241] Comparative Example 1. Battery separator and electrolyte membrane

[0242] In the above (1), 35 g of binder and 65 g of inorganic particles were mixed with NMP (N-methyl-2-pyrrolidone) to obtain 2.40 g / cm³ 3 A battery separator and an electrolyte membrane were manufactured by preparing a slurry of density and repeating the same process as in Example 1, except that the above (6) process was omitted. In (5), a composite layer was formed located on both sides of the substrate layer. The average porosity per layer of the composite layer is 65%.

[0243] Comparative Example 2. Battery separator and electrolyte membrane

[0244] In (1) above, 5 g of binder, 28.5 g of crosslinking agent, 1.5 g of photopolymerization initiator, and 65 g of inorganic particles were mixed with NMP (N-methyl-2-pyrrolidone) to obtain 1.93 g / cm² 3A battery separator and an electrolyte membrane were prepared by repeating the same process as in Example 1, except for preparing a density slurry. In (5) above, a composite layer was formed located on both sides of the substrate layer. The average porosity per layer of the composite layer is 30%.

[0245] [Evaluation Method]

[0246] Experimental Example 1. Porosity of the composite layer

[0247] The porosity of the composite layer was measured through the following process.

[0248] (1) Measuring the density, content, coating thickness, and weight of the composite layer of the slurry,

[0249] (2) Calculate by substituting the above measurement values ​​into the following formula:

[0250] The porosity (%) of the composite layer can be defined as "(slurry coating thickness - (slurry loading per unit area) / (slurry solid density)) / (slurry coating thickness) X 100 (%)".

[0251] Experimental Example 2. Ionic Conductivity

[0252] The ionic conductivity of the electrolyte membrane was evaluated according to the following process.

[0253] (1) Fabricate a coin cell in which the electrolyte membranes of the example and comparative example are positioned between SUS plates. The coin cell is of the 2016 type, and the area of ​​the electrolyte membrane is 2.83 cm² 2 (19pi)

[0254] (2) Calculate the resistance and ionic conductivity of the coin cell by applying electrochemical impedance spectroscopy (EIS) to the electrical resistance measurement and converting using the Nyquist plot method. The electrical resistance measurement is performed under AC voltage conditions of an amplitude of 10 mV and a frequency of 1,000,000 to 1,000 Hz.

[0255] Experimental Example 3. Liquid electrolyte impregnation amount

[0256] The weight change rate (%) of the battery separator and electrolyte membrane of the examples and comparative examples was calculated as the liquid electrolyte impregnation amount according to the following process.

[0257] (1) Cut a battery separator to a size of 20 mm x 60 mm to prepare a specimen, and measure its weight (W1).

[0258] (2) Fabricate an electrolyte membrane specimen of the same size as the battery separator specimen.

[0259] (3) Place tissues on both sides of the electrolyte membrane specimen, insert it into an aluminum pouch (100 mm X 80 mm), and seal it.

[0260] (3) Apply pressure to the above pouch with a press set to room temperature, 1 minute, and 1.6 MPa pressure.

[0261] (4) Open the pouch and take out the electrolyte membrane sample and measure its weight (W2).

[0262] (5) The weight ratio (W2 / W1) is converted into a percentage to determine the amount of liquid electrolyte impregnation.

[0263] Experimental Example 4. Differential Thermal Gravimetry (DTG) of Electrolyte Membrane

[0264] The DTG of the electrolyte membrane proceeded as follows.

[0265] (1) Prepare a specimen by cutting the electrolyte membrane to a size of 20 mm x 60 mm and attaching PET release films to the top and bottom thereof. The specimen is stored at 25 ℃.

[0266] (2) Prepare a specimen by applying pressure to the cut electrolyte membrane with a press (1.6 MPa, maintained for 1 minute) to remove residual liquid electrolyte from the electrolyte membrane.

[0267] (3) Introduce 10 mg of the above specimen into a thermogravimetric analyzer (PerkinElmer, TGA 4000).

[0268] (3) Conduct thermogravimetric analysis of the sample under conditions of a nitrogen (N2) atmosphere, a measurement temperature in the range of 30 ℃ to 600 ℃, a heating rate of 10 ℃ / min, and natural cooling to room temperature after reaching 600 ℃ to obtain a thermogravimetric analysis graph.

[0269] Experimental Example 5. High-temperature thermal shrinkage rate of electrolyte membrane

[0270] The high-temperature thermal shrinkage rate of the electrolyte membrane was measured through the following process.

[0271] (1) Prepare a specimen by cutting the electrolyte membrane to a size of 5 cm x 5 cm.

[0272] (2) Draw four cross-shaped dots on the surface of the Psalm. The four dots are spaced 1.5 cm apart from the center point in all directions (up, down, left, and right).

[0273] (3) Place the specimen on a glass plate and heat it in a 150°C oven for 30 minutes.

[0274] (4) Remove the specimen from the oven after heating and measure its length shrinkage rate. The shrinkage rate is calculated as a percentage of the distance to the center of the four points relative to the initial distance.

[0275] (5) The average shrinkage rate according to the measurement direction (length direction and width direction) is determined as the thermal shrinkage rate of the electrolyte membrane.

[0276] Experimental Example 6. Battery Life Characteristics

[0277] The discharge capacity and capacity retention rate of the battery manufactured with the electrolyte membrane were measured through the following process.

[0278] (1) Cut the electrolyte membrane into 32 mm x 44 mm pieces.

[0279] (2) bipolar

[0280] 1) To prepare a slurry in which a mixture comprising 94 wt% of LiNiCoMnO2 (Ni:Co:Mn=8:1:1) as the positive active material, 3 wt% of conductive carbon black (Super P; IMERYS Graphite & Carbon) as the conductive material, and 3 wt% of polyvinylidene fluoride with a weight-average molecular weight of about 800,000 as the binder is uniformly dispersed in NMP.

[0281] 2) Apply the above slurry to one side of an aluminum current collector, and then dry and roll to manufacture an anode plate having a laminated anode active material layer.

[0282] 3) Die the above anode plate into a size of 30 mm x 42 mm.

[0283] (2) Cathode

[0284] 1) To prepare a cathode material composition comprising: 95.6 wt% of a material consisting of 90 wt% of a graphite-based material in which artificial graphite and natural graphite are mixed in a weight ratio of 3:7 and 10 wt% of SiO₂ as the cathode active material; 1 wt% of acetylene black as the conductive material; 1.1 wt% of carboxymethyl cellulose (CMC) as the first binder; and 2.3 wt% of styrene butadiene rubber (SBR) as the second binder.

[0285] 2) Apply the above cathode material composition to one side of a copper current collector with a thickness of 8 μm using a comma coater, and then dry and roll to manufacture a cathode plate with a stacked cathode active material layer. The porosity and thickness of the cathode active material layer were 24% and 44 μm, respectively.

[0286] 3) Die the above cathode plate into a size of 31 mm x 43 mm.

[0287] (3) Assembly

[0288] 1) To manufacture an electrode assembly having a structure in which the positive active material layer of the positive plate and the negative active material layer of the negative plate are arranged to face each other, and the electrolyte membrane is arranged between the positive active material layer and the negative active material layer.

[0289] 2) Complete the battery by housing this electrode assembly in a pouch. The electrolyte is the same as that used in the preparation of the gel polymer electrolyte precursor composition. Five battery samples were prepared. The performance of the battery is the arithmetic mean of the five samples.

[0290] (4) Perform charge and discharge cycles of the battery. The conditions for the repeated charge and discharge test are room temperature, 2.5 to 4.2 V, and 0.1 C-rate.

[0291] (5) Repeat the charge / discharge cycle 10 times to measure the capacity retention rate. The charge capacity, discharge capacity, and discharge capacity retention rate of the battery are determined by this capacity retention rate.

[0292] [Results and Discussion]

[0293] Figure 1 shows the results of the DTG behavior analysis of the composite electrolytes of the examples and comparative examples. In Figure 1, the local minimum of each sample is identified as a decomposition peak.

[0294] Table 1 below shows the test results of the examples and comparative examples.

[0295] Battery Separator Electrolyte Membrane Composite Layer Binder Content Composite Layer Porosity Thermal Shrinkage Rate @150℃ Ionic Conductivity Electrolyte Impregnation Amount DTG 1st Peak DTG 2nd Peak Life Characteristic Weight %%%mS / cm%℃℃(100 Cycle) Example 1 30608 1.32 105952 17922 20502 1.1592 1002 2591 Comparative Example 1 356530 1.451 107918882 2530 150.2140892 1069

Claims

Substrate layer; and A composite layer located on one or both sides of the above-mentioned substrate layer and comprising a binder, a crosslinking agent, and inorganic particles; Includes, The binder content (weight%) of the above composite layer is in the range of 10 to 40, and A battery separator having a porosity (%) of the above composite layer within the range of 40 to 62. In Article 1, The above binder is a battery separator comprising a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound. In Article 1, The weight-average molecular weight (g / mol) of the above binder is in the range of 150,000 to 600,000, and A battery separator in which the second unit content (weight%) of the above binder is within the range of 10 to 25. In Article 1, A battery separator having two or more crosslinkable functional groups of the above-mentioned crosslinking agent. In Article 1, The above-mentioned crosslinking agent comprises a di(meth)acrylate compound, a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof, for a battery separator. In Article 1, The above-mentioned crosslinking agent comprises a monomeric compound, a polymeric compound, or a combination thereof, for a battery separator. In Article 1, The above crosslinking agent is trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, ethoxylated glycerol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, erythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, A battery separator comprising dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol penta(meth)acrylate, sorbitol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, polyethylene glycol di(meth)acrylate, poly(ethylene oxide-propylene oxide) di(meth)acrylate, polyurethane di(meth)acrylate, polycarbonate di(meth)acrylate, or a combination thereof. In Article 1, The above composite layer is a battery separator containing the binder in a greater weight than the crosslinking agent. In Article 1, The above-mentioned inorganic particles comprise a first inorganic particle capable of lithium ion transfer, a second inorganic particle capable of piezoelectricity, a third inorganic particle capable of flame retardancy, or a combination thereof, in a battery separator. An electrolyte membrane comprising: a substrate layer; and an electrolyte layer located on one or both sides of the substrate layer and comprising a polymer matrix and a liquid electrolyte impregnated in the polymer matrix. The above electrolyte membrane exhibits a first decomposition peak and a second decomposition peak, respectively, at a first temperature and a second temperature higher than the first temperature during differential thermal gravimetry (DTG), and The above first temperature (°C) is 200 or higher, and The above second temperature (°C) is an electrolyte membrane within the range of 90 to 150. In Article 10, The above first temperature (°C) is an electrolyte membrane within the range of 200 to 250. In Article 10, The above polymer matrix is ​​an electrolyte membrane comprising a binder-derived component and a crosslinking agent-derived component. In Article 10, The above liquid electrolyte is an electrolyte membrane comprising a non-aqueous solvent and a lithium salt. In Article 13, The above electrolyte layer is an electrolyte membrane containing a linear carbonate compound in a larger volume than a cyclic carbonate compound. In Article 14, The above linear carbonate-based compound is an electrolyte membrane comprising dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof. In Article 14, The above linear carbonate-based compound is an electrolyte membrane that is liquid at room temperature. In Article 14, The above-mentioned cyclic carbonate compound is an electrolyte membrane comprising vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof. In Article 14, The above-mentioned cyclic carbonate compound is an electrolyte membrane that is solid at room temperature. In Article 14, An electrolyte membrane in which the volume (volume%) of the linear carbonate-based compound in the above electrolyte layer is within the range of 55 to 95. It includes an anode, a cathode, and an electrolyte membrane located between the anode and the cathode, The above electrolyte membrane comprises: a substrate layer; and an electrolyte layer located on one or both sides of the substrate layer and comprising a polymer matrix and a liquid electrolyte impregnated in the polymer matrix. The above electrolyte membrane exhibits a first decomposition peak and a second decomposition peak, respectively, at a first temperature and a second temperature higher than the first temperature during differential thermal gravimetry (DTG), and The above first temperature (°C) is 200 or higher, and The battery, wherein the second temperature (°C) is within the range of 90 to 150. Preparing a slurry comprising a binder, a crosslinking agent, inorganic particles, and a first solvent; To manufacture a coating structure by coating the slurry on one or both sides of a substrate layer; Immersing the coating structure in a first mixture comprising the first solvent and the second solvent; Immersing the coating structure in a second mixture containing the second solvent; and Applying light to the above coating structure; Includes, A method for manufacturing a battery separator in which the above binder dissolves better in the first solvent than in the second solvent at room temperature. In Article 21, Immersion in the above second section is a method for manufacturing a battery separator in which the coating structure immersed in the above first section is immersed in the above second section. In Article 21, A method for manufacturing a battery separator, further comprising drying the coating structure immersed in the above-mentioned second clause. In Article 23, A method for manufacturing a battery separator by applying light to the dried coating structure. In Article 21, The first solvent above includes NMP, and The above second solvent is a method for manufacturing a battery separator containing water. Preparing a slurry comprising a binder, a crosslinking agent, inorganic particles, and a first solvent; To manufacture a coating structure by coating the slurry on one or both sides of a substrate layer; Immersing the coating structure in a first mixture comprising the first solvent and the second solvent; Immersing the coating structure in a second mixture containing the second solvent; Applying light to the above coating structure; and Immersing the coating structure in a liquid electrolyte; Includes, A method for manufacturing an electrolyte membrane in which the binder above dissolves better in the first solvent than in the second solvent at room temperature. In Article 26, Immersion in the above liquid electrolyte is a method for manufacturing an electrolyte film by immersing the above coating structure, to which light is applied, in the above liquid electrolyte.

Images