Battery

Abstract

A battery of the present invention comprises: an anode including lithium metal; a cathode including a cathode active material; and a separator positioned between the cathode and the anode. The separator includes: a base layer; a first electrolyte layer, which is positioned between the base layer and the cathode and includes a first electrolyte composition; and inorganic particles, wherein the first electrolyte composition includes a first binder, a first liquid electrolyte and a first crosslinking agent, the first crosslinking agent including a 1-1 crosslinking agent and a 1-2 crosslinking agent, and the number of crosslinkable functional groups of the 1-1 crosslinking agent can be greater than the number of crosslinkable functional groups of the 1-2 crosslinking agent.

Description

battery

[0001] This document claims the benefit of the priority date of Application No. 10-2024-0189029 filed with the Korean Intellectual Property Office on December 17, 2024, and incorporates the entire contents thereof by reference.

[0002] The present invention is a battery.

[0003] Gel polymer electrolytes (GPEs) may include a binder and a liquid electrolyte. Gel polymer electrolytes are typically incorporated into electrodes in batteries and can be combined with electrode active materials. In this case, a polyolefin-based film may be positioned between the electrodes (positive and negative electrodes) to act as a separator that prevents physical short circuits between the electrodes.

[0004] A lithium metal battery is a battery that contains lithium metal as the negative electrode active material.

[0005] The negative electrode of a lithium metal battery can expand during the charging and discharging process. This expanded negative electrode can cause cracks in the positive electrode. Cracks in the positive electrode can adversely affect battery performance. Excellent battery performance can be ensured by suppressing the expansion of the negative electrode, or by preventing cracks in the positive electrode even if the negative electrode expands.

[0006] One embodiment of the present invention comprises a negative electrode comprising lithium metal; a positive electrode comprising a positive active material; and a separator positioned between the positive electrode and the negative electrode; wherein the separator comprises a substrate layer; a first electrolyte layer positioned between the substrate layer and the positive electrode and comprising a first electrolyte composition; and inorganic particles; wherein the first electrolyte composition comprises a first binder, a first liquid electrolyte, and a first crosslinking agent, and the first crosslinking agent comprises a first-1 crosslinking agent and a first-2 crosslinking agent, and the number of crosslinkable functional groups of the first-1 crosslinking agent is greater than the number of crosslinkable functional groups of the first-2 crosslinking agent.

[0007] The number of crosslinkable functional groups of the above 1-1 crosslinking agent may be 3 or more.

[0008] The above-mentioned 1-1 crosslinking agent may include a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof.

[0009] The above-mentioned 1-1 crosslinking agent may include a monomeric compound.

[0010] The above 1-1 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.

[0011] The number of functional groups of the above 1st and 2nd crosslinking agents may be 2.

[0012] The above first and second crosslinking agents may include di(meth)acrylate-based compounds.

[0013] The above first and second crosslinking agents may include polymeric compounds.

[0014] The above first and second crosslinking agents may include 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.

[0015] The first electrolyte layer may contain a greater weight of the first-1 crosslinking agent than the first-2 crosslinking agent.

[0016] The above inorganic particles may be located in the first electrolyte layer.

[0017] The above separator further comprises a first inorganic layer located between the substrate layer and the first electrolyte layer; and the inorganic particles may be located in the first inorganic layer.

[0018] The above substrate layer can come into contact with the above cathode.

[0019] The first electrolyte layer may include a cyclic carbonate compound, a linear carbonate compound, or a combination thereof.

[0020] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0021] The above linear carbonate-based compound may be liquid at room temperature.

[0022] 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.

[0023] The above cyclic carbonate compound may be solid at room temperature.

[0024] The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer may be in the range of 5 to 95.

[0025] The above substrate layer may include a polyolefin-based film.

[0026] The first electrolyte layer may include a cured product of the first electrolyte composition.

[0027] The above separator may further include a second electrolyte layer located between the substrate layer and the cathode and comprising a second electrolyte composition.

[0028] The above inorganic particles may be located in each of the first electrolyte layer and the second electrolyte layer.

[0029] The above separator further comprises a first inorganic layer located between the substrate layer and the first electrolyte layer; and a second inorganic layer located between the substrate layer and the second electrolyte layer; and the inorganic particles may be located in each of the first inorganic layer and the second inorganic layer.

[0030] The above inorganic particles include a first inorganic particle that is flame-retardant and a second inorganic particle that is lithium ion-transmitting, and the first inorganic particle may be located in the first inorganic layer and the second inorganic particle may be located in the second inorganic layer.

[0031] The first inorganic particle above 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.

[0032] The above second inorganic particle is Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Aly 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.

[0033] The first binder above may include a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound.

[0034] 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.

[0035] The battery of the present invention can protect the positive electrode even when the negative electrode expands, and at the same time, can exhibit excellent electrical performance.

[0036] This document may use ordinal numbers such as “first” and “second” when referring to multiple components. There is no priority among the components.

[0037] 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).

[0038] 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.

[0039] In this document, the numerical range “within the range of A to B” means “A or greater and B or less.”

[0040] 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.

[0041] The present document describes the invention in more detail below.

[0042] One embodiment (Embodiment) of the present invention is a battery.

[0043] In this document, a battery may include any element that performs an electrochemical reaction.

[0044] 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.

[0045] 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).

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] The battery of the present invention is a lithium metal battery. That is, the negative electrode comprises lithium metal. Specifically, the negative electrode may comprise lithium metal as a negative electrode active material. More specifically, the negative electrode may comprise copper foil as a negative electrode current collector and may comprise lithium metal as a negative electrode active material. The negative electrode may comprise lithium metal as a main component (e.g., content of 90 weight% or more) as the negative electrode active material.

[0053] The separator is located between the anode and the cathode. Specifically, the separator may be located between the anode active material layer and the cathode active material layer facing each other. The separator can prevent physical contact (short circuit) between the anode and the cathode in the battery. A charge carrier (e.g., lithium ions) can move through the separator between the electrodes.

[0054] The battery of the present invention includes a separator of a specific structure.

[0055] The above separator comprises a substrate layer; a first electrolyte layer; and inorganic particles. The above separator may further comprise a second electrolyte layer. The second electrolyte layer is described later.

[0056] The above substrate layer can cause a fluid to move from one side of the substrate layer to another side.

[0057] The first electrolyte layer is located on one surface of the substrate layer. Specifically, the first electrolyte layer is located between one surface of the substrate layer and the anode. More specifically, the first electrolyte layer is located between one surface of the substrate layer and the anode active material layer. Even more specifically, the first electrolyte layer is located between one surface of the substrate layer and the anode active material layer in a state facing each other.

[0058] The first electrolyte layer above can provide a path for a charge carrier to move to the separator.

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

[0060] The above electrolyte layer comprises an electrolyte composition. The composition included in the first electrolyte layer is the first electrolyte composition. The composition included in the second electrolyte layer is the second electrolyte composition. The above electrolyte composition may be a composition of a gel polymer electrolyte.

[0061] In this document, the gel polymer electrolyte is an electrolyte in the gel phase and comprises a polymer matrix and a liquid electrolyte impregnated therein. Here, the polymer matrix can physically support the gel polymer electrolyte. The liquid electrolyte can impart ion conductivity to the gel polymer electrolyte.

[0062] In this document, an electrolyte composition refers to a composition that can become an electrolyte either by itself or through a specific reaction.

[0063] The first electrolyte composition comprises a first binder, a first liquid electrolyte, and a first crosslinking agent.

[0064] The first binder can form a polymer matrix alone or together with the first crosslinking agents.

[0065] The first liquid electrolyte can be impregnated into the polymer matrix formed by the first binder. The first liquid electrolyte can impart ion conductivity to the gel polymer electrolyte.

[0066] The first crosslinking agent may form a polymer matrix in the gel polymer electrolyte alone or together with the binder. The first crosslinking agent may link the binders and / or crosslinking agents in the polymer matrix.

[0067] The first crosslinking agent comprises multiple types of crosslinking agents. Specifically, the first crosslinking agent comprises a first-1 crosslinking agent and a first-2 crosslinking agent having different numbers of crosslinkable functional groups.

[0068] The number of crosslinkable functional groups of the first-1 crosslinking agent is greater than the number of crosslinkable functional groups of the first-2 crosslinking agent. 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 group may be a functional group that acts to connect binders and / or crosslinking agents in the polymer matrix.

[0069] If the first electrolyte composition includes a 1-1 crosslinking agent and a 1-2 crosslinking agent having different numbers of crosslinkable functional groups, the first electrolyte layer can be formed at a rapid crosslinking rate and can exhibit high crosslinking density and appropriate flexibility.

[0070] Although not limited to theory, it is believed that the excellent characteristics of the first electrolyte layer, such as the crosslinking rate, crosslinking density, and flexibility, are due to the fact that the first-1 crosslinking agent can form a dense crosslinking structure and the first-2 crosslinking agent can provide a space for the liquid electrolyte to be impregnated.

[0071] If the first electrolyte composition contains one type of crosslinking agent, or if the first electrolyte composition contains multiple crosslinking agents having the same number of crosslinkable functional groups, only a hard electrolyte layer is formed, or only a soft electrolyte layer with a slow rate is formed, making it difficult to simultaneously improve ion conductivity and leakage characteristics.

[0072] Below, this document explains the above-mentioned battery in more detail.

[0073] The number of crosslinkable functional groups of the above-mentioned 1-1 crosslinking agent may be 3 or more. In this case, the above-mentioned 1-1 crosslinking agent may form a dense crosslinking structure. Specifically, the number of crosslinkable functional groups of the above-mentioned 1-1 crosslinking agent may be 6 or less, 5 or less, or 4 or less.

[0074] 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 first-1 crosslinking agent and the above-mentioned first-2 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.

[0075] Accordingly, the above-mentioned 1-1 crosslinking agent may include a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof.

[0076] Specifically, the 1-1 crosslinking agent may include a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, a hexaacrylate compound, or a combination thereof.

[0077] More specifically, the first-1 crosslinking agent may include a triacrylate-based compound, a tetraacrylate-based compound, or a combination thereof.

[0078] More specifically, the above-mentioned 1-1 crosslinking agent may include a triacrylate-based compound.

[0079] The above-mentioned 1-1 crosslinking agent may include a monomeric compound. The monomeric crosslinking agent may mean that the remaining moiety, excluding the crosslinking functional group, is of monomer origin.

[0080] The above 1-1 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.

[0081] Specifically, the 1-1 crosslinking agent comprises 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, It may include dipentaerythritol hexaacrylate, ethoxylated dipentaerythritol hexaacrylate, sorbitol hexaacrylate, or a combination thereof.

[0082] More specifically, the 1-1 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, pentaerythritol tetraacrylate, ethoxylated pentaerythritol tetraacrylate, propoxylated pentaerythritol tetraacrylate, erythritol tetraacrylate, ditrimethylolpropane tetraacrylate, or a combination thereof.

[0083] More specifically, the 1-1 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.

[0084] The number of crosslinkable functional groups of the first-2 crosslinking agent may be less than the number of crosslinkable functional groups of the first-1 crosslinking agent. If the number of crosslinkable functional groups of the first-1 crosslinking agent is 3, the number of crosslinkable functional groups of the first-2 crosslinking agent may be 2. If the number of crosslinkable functional groups of the first-1 crosslinking agent is 4, the number of crosslinkable functional groups of the first-2 crosslinking agent may be 2 or 3. If the number of crosslinkable functional groups of the first-1 crosslinking agent is 5, the number of crosslinkable functional groups of the first-2 crosslinking agent may be 2, 3, or 4. If the number of crosslinkable functional groups of the first-1 crosslinking agent is 6, the number of crosslinkable functional groups of the first-2 crosslinking agent may be 2, 3, 4, or 5.

[0085] Specifically, apart from the number of crosslinkable functional groups of the first-1 crosslinking agent, the number of crosslinkable functional groups of the first-2 crosslinking agent may be 2. When the number of crosslinkable functional groups of the first-2 crosslinking agent is as small as possible, the first-2 crosslinking agent may provide a space for the liquid electrolyte to be impregnated.

[0086] The first crosslinking agent may include a photoreactive functional group, specifically a (meth)acryloyl group, and since the number of functional groups of the first and second crosslinking agents may be 2, the first and second crosslinking agents may include a di(meth)acrylate-based compound.

[0087] In addition, since it is preferable that the photoreactive functional group includes an acryloyl group, the first and second crosslinking agents may include a diacrylate-based compound.

[0088] The above-mentioned first and second crosslinking agents may include polymeric compounds. The above-mentioned polymeric crosslinking agent may mean that the remaining moiety, excluding the crosslinking functional group, is of polymeric origin.

[0089] Preferably, the first-1 crosslinking agent comprises a monomeric compound, and the first-2 crosslinking agent may comprise a polymeric compound. That is, when the crosslinking agent with a greater number of functional groups is monomeric and the crosslinking agent with a smaller number of functional groups is polymeric, excellent properties such as the crosslinking rate, crosslinking density, and flexibility of the electrolyte layer can be more appropriately exhibited.

[0090] The above first and second crosslinking agents may include 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.

[0091] Specifically, the first and second crosslinking agents may include polyethylene glycol diacrylate, poly(ethylene oxide-propylene oxide) diacrylate, polyurethane diacrylate, polycarbonate diacrylate, or a combination thereof.

[0092] More specifically, the first and second crosslinking agents may include polyethylene glycol diacrylate, polyurethane diacrylate, or a combination thereof.

[0093] More specifically, the first and second crosslinking agents may include polyurethane diacrylate.

[0094] When the first and second crosslinking agents include a polymeric compound, the molecular weight of the polymeric compound may also be controlled. The first and second crosslinking agents may include polyethylene glycol diacrylate with a molecular weight in the range of 400 g / mol to 700 g / mol, polyurethane diacrylate with a molecular weight in the range of 1400 g / mol to 2100 g / mol, or a combination thereof. Specifically, the first and second crosslinking agents may include polyurethane diacrylate with a molecular weight in the range of 1400 g / mol to 2100 g / mol.

[0095] The mixing ratio of the above-mentioned 1-1 crosslinking agent and the above-mentioned 1-2 crosslinking agent can also be appropriately adjusted.

[0096] The ratio (C1-1:C1-2) of the weight of the first-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the first-2 crosslinking agent (C1-2) of the first electrolyte layer may be in the range of 1:9 to 9:1.

[0097] Preferably, the ratio (C1-1:C1-2) of the weight of the first-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the first-2 crosslinking agent (C1-2) of the first electrolyte layer may be 1.5:8.5 or higher, 2:8 or higher, 2.5:7:5 or higher, 3:7 or higher, 3.5:6.5 or higher, 4:6 or higher, or 4.5:5.5 or higher. The ratio (C1-1:C1-2) of the weight of the first-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the first-2 crosslinking agent (C1-2) of the first electrolyte layer may be 8.5:1.5 or lower, 8:2 or lower, 7.5:2.5 or lower, 7:3 or lower, 6.5:3.5 or lower, 6:4 or lower, or 5.5:4.5 or lower.

[0098] Meanwhile, the first electrolyte layer may contain a greater weight of the first-1 crosslinking agent than the first-2 crosslinking agent. The molecular weight of a crosslinking agent with fewer crosslinkable functional groups is higher than that of a crosslinking agent with more crosslinkable functional groups. For this reason, the number of crosslinking bonds per unit volume or unit mass of a crosslinking agent with fewer crosslinkable functional groups is lower compared to a crosslinking agent with more crosslinkable functional groups. Therefore, a crosslinking agent with fewer crosslinkable functional groups may be disadvantageous for smooth crosslinking progress. Consequently, it may be more advantageous for the first electrolyte layer to contain the first-1 crosslinking agent in a greater weight than the first-2 crosslinking agent. Furthermore, at this time, the elasticity of the battery, specifically the electrolyte layer, and more specifically the first electrolyte layer, may be increased.

[0099] The weight of the 1-1 crosslinking agent of the first electrolyte layer and the weight of the 1-2 crosslinking agent of the first electrolyte layer can be controlled by the weight of the 1-1 crosslinking agent of the first electrolyte composition and the weight of the 1-2 crosslinking agent of the first electrolyte composition.

[0100] The above-mentioned inorganic particles may exist in various forms in the battery.

[0101] The inorganic particles may be located in the first electrolyte layer. Specifically, the first electrolyte composition may further include the inorganic particles. When the first electrolyte composition is cured, the inorganic particles may be located in the first electrolyte layer. At this time, the first electrolyte layer may be in direct contact with the substrate layer. There may not be a separate layer between the first electrolyte layer and the substrate layer.

[0102] The above inorganic particles may exist as a separate layer from the substrate layer and the first electrolyte layer in the battery.

[0103] The above separator may further include a first inorganic layer located between the substrate layer and the first electrolyte layer. In this case, the inorganic particles may be located in the first inorganic layer. In this case, the first electrolyte layer or the first electrolyte composition may not contain inorganic particles.

[0104] In addition, at this time, the substrate layer may come into contact with the cathode. Specifically, the substrate layer may come into direct contact with the cathode. More specifically, the substrate layer may come into direct contact with the cathode active material layer. During the charging process of the battery, the cathode may expand due to lithium dendrites, and as a result, the anode may be damaged; however, if the substrate layer comes into contact with the cathode, damage to the anode can be minimized.

[0105] The type of the inorganic particles may vary depending on the characteristics imparted by the inorganic particles to the battery separator. Specifically, the inorganic particles may include a combination of multiple types of inorganic particles capable of imparting different characteristics to the battery separator. If the battery separator includes multiple types of inorganic particles, it may exhibit improved mechanical properties, thermal properties, and ion conductivity.

[0106] The liquid electrolyte may be impregnated into the binder, specifically the polymer matrix formed by the binder. The liquid electrolyte may further comprise a non-aqueous solvent, a lithium salt, and an additive. The lithium salt may be dissolved in the non-aqueous solvent.

[0107] The above-mentioned non-aqueous solvent may refer to an organic solvent that does not contain water or, even if water is included, contains only trace amounts. 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.

[0108] The above ether-based compound may include dimethoxyethane, diethoxyethane, tetrahydrofuran, or a combination thereof.

[0109] The above ester compound may include N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (γ-butyrolactone), or a combination thereof.

[0110] The above-mentioned polar functional group-containing compound may include dimethyl sulfoxide, acetonitrile, or a combination thereof.

[0111] The 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. That is, the first electrolyte layer may include a cyclic carbonate-based compound, a linear carbonate-based compound, or a combination thereof. Preferably, the first electrolyte layer may include a linear carbonate-based compound and a cyclic carbonate-based compound.

[0112] The volume of the carbonate-based compound in the above electrolyte layer can be controlled by the volume of the carbonate-based compound in the above electrolyte composition.

[0113] In this document, linear carbonate compounds refer to open diesters 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.

[0114] 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.

[0115] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0116] Specifically, the linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0117] More specifically, the linear carbonate-based compound may include ethylmethyl carbonate.

[0118] The above linear carbonate-based compound may be liquid at room temperature.

[0119] 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.

[0120] Specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0121] More specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

[0122] From the perspective of the miscibility of the aforementioned binder and liquid electrolyte, the control of the viscosity of the gel polymer composition, 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.

[0123] The above cyclic carbonate-based compound may be solid at room temperature. Specifically, the above cyclic carbonate-based compound may include ethylene carbonate.

[0124] 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.

[0125] 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.

[0126] The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer may be in the range of 5 to 95.

[0127] Preferably, the volume (volume%) of the linear carbonate-based compound in the first electrolyte layer may be 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, or 75 or more. The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer may be 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or 25 or less.

[0128] The volume (volume%) of the cyclic carbonate-based compound in the first electrolyte layer may be in the range of 5 to 95.

[0129] Preferably, the volume (volume%) of the cyclic carbonate-based compound of the first electrolyte layer may be 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, or 75 or more. The volume (volume%) of the cyclic carbonate-based compound of the first electrolyte layer may be 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or 25 or less.

[0130] The above lithium salt may refer to a material that decomposes into lithium cations and anions upon dissociation.

[0131] The above 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 LiN(CF3SO2)2.

[0132] 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.

[0133] 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.

[0134] 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 first electrolyte layer may be thicker than the substrate layer.

[0135] The above substrate layer may include a polyolefin-based film. Specifically, the above substrate layer may include a porous polyolefin-based film.

[0136] Here, a polyolefin-based porous film refers to a porous film containing a polyolefin-based resin as a main component.

[0137] 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.

[0138] The weight average molecular weight of the component included in the above polyolefin resin is 3×10 5 Up to 15×10 6 It 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.

[0139] 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.

[0140] 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.

[0141] The above electrolyte layer may be formed by curing the above electrolyte composition. The above electrolyte layer may include a cured product of the above electrolyte composition. Specifically, the first electrolyte layer may include a cured product of the first electrolyte composition.

[0142] The above curing method may include, for example, thermal curing, photocuring, and thermal-photo dual curing. Preferably, the curing method may be photocuring.

[0143] A cured product of a composition may refer to a composition that has undergone a chemical process in which it hardens or solidifies as the structure of the components contained in the composition changes due to chemical reactions between those components. This curing may differ from drying, which is a physical process in which a portion of the composition dries or hardens as some of the components contained in the composition (e.g., solvents such as water, volatile components) evaporate.

[0144] The first electrolyte layer may further include an initiator. Specifically, the first electrolyte composition may further include an initiator.

[0145] When a predetermined stimulus is applied, the initiator can initiate a reaction in which the binder forms a polymer matrix.

[0146] The above initiator may include a thermal polymerization initiator, a photopolymerization initiator, or a combination thereof. Preferably, the initiator may include a photopolymerization initiator.

[0147] 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.

[0148] 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.

[0149] 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).

[0150] In addition, the electrolyte composition may be impregnated into the pores of the substrate layer. Accordingly, at least a portion of the electrolyte layer containing a cured product of the electrolyte composition may be impregnated into the pores of the substrate layer.

[0151] A UV curing method may be applied to form the electrolyte layer on the above substrate layer. The UV curing method is a method of forming cross-linked structures between binders, between binders and crosslinking agents, or between crosslinking agents using an external force. According to the UV curing method, the process of the binder forming a polymer matrix, the process of the binder and inorganic particles dispersing, and the process of the liquid electrolyte impregnating can proceed in the same step.

[0152] The above UV curing method may include the following steps. The number of each step does not indicate the order of the steps:

[0153] (1) Prepare the above electrolyte composition;

[0154] (2) Applying the electrolyte composition to one or both sides of the substrate layer; and

[0155] (3) Irradiate the above electrolyte composition with UV.

[0156] In the above (1) process, the preparation of the electrolyte composition may include directly manufacturing the electrolyte composition or applying a previously manufactured electrolyte composition.

[0157] Conditions such as the application method and thickness of the above electrolyte composition are not particularly limited.

[0158] The conditions of UV irradiation on the above electrolyte composition are not particularly limited.

[0159] As described below, the separator may further include a second electrolyte layer. Specifically, the separator may further include a second electrolyte layer located between the substrate layer and the cathode and comprising a second electrolyte composition.

[0160] The second electrolyte layer may be located on the other side of the substrate layer. Specifically, the second electrolyte layer may be located between the other side of the substrate layer and the cathode. More specifically, the second electrolyte layer may be located between the other side of the substrate layer and the cathode active material layer. Even more specifically, the second electrolyte layer may be located between the other side of the substrate layer and the cathode active material layer in a state where they face each other.

[0161] The second electrolyte layer may also include an electrolyte composition. The second electrolyte layer may include a second electrolyte composition. The second electrolyte composition may include a second binder, a second liquid electrolyte, and a second crosslinking agent.

[0162] Unless otherwise specifically stated, the description of the first electrolyte layer may be applied to the description of the second electrolyte layer.

[0163] The first electrolyte layer and the second electrolyte layer may exhibit different physical properties. Therefore, in the battery of the present invention in which the positive and negative electrodes exhibit different characteristics, the separator can balance the positive and negative electrodes.

[0164] Specifically, the first electrolyte layer may exhibit a harder characteristic than the second electrolyte layer. The second electrolyte layer may exhibit a softer characteristic than the first electrolyte layer.

[0165] In contrast, the stiffness of the electrolyte layer may exhibit an inverse relationship with ionic conductivity. That is, the ionic conductivity of the first electrolyte layer may be lower than that of the second electrolyte layer. The ionic conductivity of the second electrolyte layer may be higher than that of the first electrolyte layer. Although not limited to theory, this is thought to be because the second electrolyte layer contains a larger amount of liquid electrolyte compared to the first electrolyte layer. Additionally, this is also thought to be because the contactability of the second electrolyte layer with respect to adjacent electrodes is superior to that of the first electrolyte.

[0166] The stiffness and ionic conductivity of the above electrolyte layer may vary depending on the solid content of the electrolyte composition included in each layer. An electrolyte composition with a higher solid content may result in a harder electrolyte layer, and an electrolyte composition with a lower solid content may increase the ionic conductivity of the electrolyte layer.

[0167] Accordingly, the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

[0168] One side of the separator, in which two electrolyte layers with opposite characteristics are arranged to face each other in the substrate layer, can buffer external physical stimuli, while the other side can increase the ion conductivity of the battery.

[0169] The battery of the present invention is a lithium metal battery comprising lithium metal as the negative electrode. The negative electrode may expand during the charging and discharging process, thereby causing cracks in the positive electrode. Here, the first electrolyte layer of the battery separator of the present invention may be located on the positive electrode side, and the second electrolyte layer may be located on the negative electrode side. During the charging process of the battery, the negative electrode may expand due to a side reaction between the second electrolyte layer and the negative electrode (lithium metal), and as a result, the positive electrode may be damaged; however, if the second electrolyte layer, which is relatively soft, is located on the negative electrode side, damage to the positive electrode can be minimized.

[0170] The solid content of the above electrolyte composition may be a value converted into a percentage by dividing the weight of the dried product of the electrolyte composition itself by the weight before drying. This document discusses the method for measuring the solid content of the above electrolyte composition in more detail in the Examples section.

[0171] The solid content of the above electrolyte composition may be determined according to the content of the liquid electrolyte included in the electrolyte composition, the number of crosslinks that may occur in the electrolyte layer, etc. That is, the solid content of the electrolyte composition may increase when a crosslinker with a greater number of functional groups participating in the crosslinking reaction between the binder and the crosslinker, or between the crosslinkers, is used in larger quantities, or when the crosslinker content of the electrolyte composition is higher.

[0172] The solid content (SC1, weight%) of the first electrolyte composition above may be in the range of 30 to 60.

[0173] The solid content (SC2, weight%) of the second electrolyte composition above may be in the range of 10 to 50.

[0174] The difference between the solid content of the first electrolyte composition and the solid content of the second electrolyte composition can be determined by considering the margin of error. In the present invention, even if the ratio (SC1 / SC2) of the solid content of the first electrolyte composition (SC1, weight%) and the solid content of the second electrolyte composition (SC2, weight%) is not 1 in itself, if the ratio is less than 1.05, the solid content of the first electrolyte composition and the solid content of the second electrolyte composition can be considered to be the same.

[0175] Accordingly, the ratio (SC1 / SC2) of the solid content (SC1, weight%) of the first electrolyte composition and the solid content (SC2, weight%) of the second electrolyte composition may be 1.05 or higher.

[0176] As described above, one method of designing the solid content of the first electrolyte composition to be greater than the solid content of the second electrolyte composition is to introduce a difference in the liquid electrolyte content. Specifically, the first liquid electrolyte content (weight%) of the first electrolyte composition may be less than the second liquid electrolyte content (weight%) of the second electrolyte composition.

[0177] The liquid electrolyte content (weight%) of the first electrolyte layer may be in the range of 40 to 70.

[0178] The liquid electrolyte content (weight%) of the second electrolyte layer above may be in the range of 50 to 90.

[0179] The solid content of the above electrolyte composition can be determined according to the number of crosslinks that may occur in the electrolyte composition. That is, the solid content of the electrolyte composition may increase when a crosslinking agent with a greater number of functional groups participating in crosslinking is included in larger quantities, or when the total crosslinking agent content of the electrolyte composition is high.

[0180] For example, the content of the 1-1 crosslinking agent of the first electrolyte composition may be greater than the content of the 1-2 crosslinking agent of the second electrolyte composition. This may mean that the total crosslinking agent content of the first electrolyte composition is greater than the total crosslinking agent content of the second electrolyte composition.

[0181] When the above-mentioned inorganic particles are located in the electrolyte layer, the above-mentioned inorganic particles may be located in each of the first electrolyte layer and the second electrolyte layer.

[0182] When the above-mentioned inorganic particles are located in a layer separate from the electrolyte layer, their arrangement can be determined more specifically.

[0183] The above separator may further include a first inorganic layer located between the substrate layer and the first electrolyte layer; and a second inorganic layer located between the substrate layer and the second electrolyte layer.

[0184] The above inorganic particles may be located in each of the first inorganic layer and the second inorganic layer.

[0185] The above inorganic particles may include a first inorganic particle and a second inorganic particle. The first inorganic particle and the second inorganic particle may differ in imparted characteristics, particle size, shape, density, etc. Specifically, the inorganic particles may include a flame-retardant first inorganic particle and a lithium ion-transmitting second inorganic particle.

[0186] The first inorganic particle may be located closer to the anode. The first inorganic particle may be located in the first inorganic layer.

[0187] The second inorganic particle may be located closer to the cathode. The second inorganic particle may be located in the second inorganic layer.

[0188] The above flame-retardant inorganic particles can add flame-retardant properties to the battery separator and prevent a rapid rise in the internal temperature of the battery.

[0189] The first 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 first inorganic particle may include ZrO2, Y2O3, Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof. More preferably, the first inorganic particle may include Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof.

[0190] 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.

[0191] The above second 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 It may include (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2), or a combination thereof. Preferably, the second inorganic particle is Li 6+x La3Zr 2-y M y O 12-z It may include (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2).

[0192] The binder can form a framework in the electrolyte layer formed by the gel polymer electrolyte composition. The binder has appropriate crystallinity and polarity to increase the ion conductivity of the battery separator. In particular, the polar portion of the binder can combine with the crosslinking agent. At this time, the binder can form a crosslinked structure in the electrolyte layer.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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 can affect the crystallinity of the above-mentioned fluorine-based binder, the ionic conductivity of the above-mentioned composite electrolyte, and the mechanical strength.

[0198] 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.

[0199] 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.

[0200] 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.

[0201] The weight average molecular weight of the above fluorine-based binder can be measured by gel permeation chromatography.

[0202] 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.

[0203] Hereinafter, the present invention is described in more detail through examples and comparative examples. However, the present invention is not limited to the examples.

[0204] [Preparation Example]

[0205] Example 1. Battery

[0206] The battery was manufactured according to the following process.

[0207] (1) Prepare a dispersion by dispersing 10 g of inorganic particles in 20 g of deionized water. The inorganic particles are ALK-L1 (polygonal alumina; average size: 300 nm; true density: 3.95 g / cm³) of Daehan Ceramics. 3 )am.

[0208] (2) 0.1 g of thickener and 1 g of dispersant are added to the above dispersion and stirred with a homogenizer to prepare a slurry. The thickener is WEALTHY’s CMC2020 (carboxymethyl cellulose; substitution rate: 1.00; viscosity: 15 mPa.s). The dispersant is Toyochem’s CSB-400 (acrylic copolymer; glass transition temperature: -25 ℃; viscosity: 30 cP; solid content: 40 wt%).

[0209] (3) Apply the above slurry only to the upper surface of the substrate layer using a slot die and dry it to produce a structure with a total thickness of 9 μm in which an inorganic layer is located on one surface of the substrate layer. The substrate layer is Asahi Kasei ND408A (PE film; thickness: 8 μm; porosity: 38%).

[0210] (4) Prepare a solution by adding 4.28 g of binder, 8.56 g of 1-1 crosslinking agent, and 2.14 g of 1-2 crosslinking agent to 85 g of liquid electrolyte, and then mix the solution with a homogenizer, and then add 0.2 g of photopolymerization initiator to the solution to prepare a first electrolyte composition. The binder is Arkema’s Kynar 2501-20 (polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP); weight average molecular weight: 350,000 g / mol; HFP substitution rate: 18.6 wt%). The first crosslinking agent is Miwon Specialty Chemical’s M340 (pentaerythritol triacrylate; PETA). The second crosslinking agent is Miwon Specialty Chemical’s Miramer PU2100 (polyurethane diacrylate, weight average molecular weight: 1400). The above photopolymerization initiator is IGM's Omnirad TPO-L (Ethyl (2,4,6-trimethylbenzoyl) phenyl phosphinate). The above 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 LiTFSI is dissolved, and 2% of vinylene carbonate (VC) is added by weight.

[0211] (5) Apply the first electrolyte composition to the inorganic layer of the structure on which the inorganic layer is located using a slot die, and cure it with UV irradiation to produce a battery separator with a total thickness of 30 μm.

[0212] (6) bipolar

[0213] 1) To prepare a slurry in which a mixture comprising 94 wt% of LiNiCoMnO2 (Ni:Co:Mn=8:1:1) as a positive active material, 3 wt% of conductive carbon black (Super P; IMERYS Graphite & Carbon) as a conductive material, and 3 wt% of polyvinylidene fluoride with a weight-average molecular weight of about 800,000 as a binder is uniformly dispersed in NMP (N-methyl-2-pyrrolidone).

[0214] 2) The above slurry is applied to one side of a 20 µm thick aluminum current collector at 4.0 mAh / cm 2 Applying a loading amount, followed by drying and rolling to manufacture an anode plate with a laminated anode active material layer.

[0215] 3) The above anode plate is 1.54 cm 2 Stamping into (14 pi) size.

[0216] (7) Cathode

[0217] 1) Fabricate a cathode plate with a total thickness of 100 μm by rolling lithium metal (cathode active material layer) onto a copper plate with a thickness of 10 μm.

[0218] 2) The above cathode plate is 1.76 cm 2 Stamping to a size of (15 pi).

[0219] (8) Assembly

[0220] 1) 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 2.83 cm 2 Manufacturing an electrode assembly having a structure in which the battery separator cut to a size of (19 pi) is placed between the positive active material layer and the negative active material layer.

[0221] 2) Complete the battery by housing this electrode assembly in a pouch. Five battery samples were prepared. The performance of the above battery is the arithmetic mean of the five samples.

[0222] Example 2. Battery

[0223] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that 5 g of the first-1 crosslinking agent and 5 g of the first-2 crosslinking agent were added.

[0224] Example 3. Battery

[0225] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that 2 g of the first-1 crosslinking agent and 8 g of the first-2 crosslinking agent were added.

[0226] Example 4. Battery

[0227] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that Miwon Specialty Chemical’s M300 (trimethylolpropane triacrylate) was added as the first-1 crosslinking agent.

[0228] Example 5. Battery

[0229] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that Miwon Specialty Chemical’s M300 (trimethylolpropane triacrylate) was used as the first-1 crosslinking agent, and 5 g of the first-1 crosslinking agent and 5 g of the first-2 crosslinking agent were added.

[0230] Example 6. Battery

[0231] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that the non-aqueous solvent was changed to a non-aqueous solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 7:3.

[0232] Example 7. Battery

[0233] A battery was manufactured by repeating the same process as in Example 1, except that in (4) above, the non-aqueous solvent was changed to a non-aqueous solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 7:3, and M300 (trimethylolpropane triacrylate) of Miwon Specialty Chemicals was added as the first-1 crosslinking agent.

[0234] Comparative Example 1. Battery

[0235] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that 10 g of the first-1 crosslinking agent was added and the first-2 crosslinking agent was not added.

[0236] Comparative Example 2. Battery

[0237] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that 10 g of Miwon Specialty Chemical’s M300 (trimethylolpropane triacrylate) was added as the first-1 crosslinking agent, and the first-2 crosslinking agent was not added.

[0238] Comparative Example 3. Battery

[0239] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that 5 g of Miwon Specialty Chemical’s M340 (pentaerythritol triacrylate; PETA) and 5 g of Miwon Specialty Chemical’s M300 (trimethylolpropane triacrylate) were added as crosslinking agents.

[0240] Comparative Example 4. Battery

[0241] In the above (4), a battery was manufactured by repeating the same process as in Example 1, except that the first-1 crosslinking agent was not added and 10 g of the first-2 crosslinking agent was added.

[0242] [evaluation]

[0243] Experimental Example 1. Ionic Conductivity

[0244] The resistance and ionic conductivity of the battery separator were evaluated according to the following process.

[0245] (1) Fabricating a coin cell in which the battery separator of the example and comparative example is positioned between SUS plates. The coin cell is of the 2016 type, and the area of ​​the battery separator is 2.83 cm² 2 (19pi)

[0246] (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.

[0247] Experimental Example 2. Battery Performance

[0248] The discharge capacity and capacity retention rate of the batteries in the examples and comparative examples were measured by the following process.

[0249] (1) Prepare an electrochemical analysis device (Toyo, Toscat-3100).

[0250] (2) Charge the battery using the CC-CV method under conditions of 0.2 C, 4.3 V, and cut-off 0.05 C, and discharge the battery under conditions of 0.5 C, 3.0 V, and cut-off 0.05 C.

[0251] (3) Measure the initial (1 cycle) charge and discharge capacity.

[0252] (4) Measure the charge and discharge capacity after repeating 50 cycles.

[0253] [Results and Discussion]

[0254] Table 1 below shows the test results of the examples and comparative examples.

[0255] Classification Unit Preliminary Comparative Example 1 2 3 4 5 6 7 1 2 3 4 Resistance (Ohm) 1.4 2 1.3 9 1.2 1 1.3 6 1.3 8 1.2 8 1.2 5 1.5 8 1.5 3 1.5 4 X Ion Conductivity (mS / cm) 1.2 2 1.3 5 1.4 5 1.3 9 1.3 9 1.3 1 1.3 5 1.0 6 1.1 3 1.0 8 X Cycles Performance 1st (Charging) mAh 44.8 42.8 39.2 41.1 42.1 44.2 44.6 40.2 41.8 40.9X 1st (Discharging) mAh 44.2 41.9 38.4 40.2 41.8 43.2 43.5 39.5 40.6 40.1X 50th (Discharging) mAh 43.3 39.1 35.1 37.6 38.8 42.6 42.7 35.5 37.0 36.8X Retention Rate % 98.0 93.3 91.4 93.5 92.8 98.5 98.2 89.9 92.6 91.7XX: Physical properties cannot be measured due to non-formation of gel

[0256] Referring to Table 1, it is confirmed that an embodiment of the present invention, in which the electrolyte layer of the battery separator contains multiple crosslinking agents with different numbers of functional groups and the electrolyte layer is located on the positive side, has superior resistance and ion conductivity characteristics and battery cycle performance compared to a comparative example that does not.

[0257] In addition, by referring to the comparison between Example 1 and Example 6, and the comparison between Example 4 and Example 7, it is confirmed that battery separators (Examples 6 and 7) in which a non-aqueous solvent containing a higher proportion of cyclic carbonate compounds than linear carbonate compounds exhibit lower resistance and higher ionic conductivity than expected. This is thought to be because the boiling point of cyclic carbonate compounds is generally higher than that of linear carbonate compounds, resulting in a lower proportion of components volatilizing at room temperature.

Claims

A cathode containing lithium metal; Anode comprising a positive electrode active material; and A separator located between the anode and the cathode; Includes, The above separator is Base layer; A first electrolyte layer located between the above substrate layer and the above anode, comprising a first electrolyte composition; and Inorganic particles; Includes, The first electrolyte composition comprises a first binder, a first liquid electrolyte, and a first crosslinking agent, and The above-mentioned first crosslinking agent comprises a first-1 crosslinking agent and a first-2 crosslinking agent, and A battery in which the number of crosslinkable functional groups of the above 1-1 crosslinking agent is greater than the number of crosslinkable functional groups of the above 1-2 crosslinking agent. In Article 1, A battery having 3 or more crosslinkable functional groups of the above-mentioned 1-1 crosslinking agent. In Article 1, The above-mentioned 1-1 crosslinking agent comprises a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof. In Article 1, The above-mentioned 1-1 crosslinking agent is a battery comprising a monomeric compound. In Article 1, The above 1-1 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 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, or a combination thereof. In Article 1, A battery in which the number of functional groups of the above 1-2 crosslinking agents is 2. In Article 1, The above-mentioned first and second crosslinking agents are batteries comprising di(meth)acrylate-based compounds. In Article 1, The above-mentioned first and second crosslinking agents are a battery comprising a polymeric compound. In Article 1, The above-mentioned first and second crosslinking agents comprise 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, A battery in which the first electrolyte layer contains a 1-1 crosslinking agent in a greater weight than a 1-2 crosslinking agent. In Article 1, The above-mentioned inorganic particles are located in the first electrolyte layer of the battery. In Article 1, The above separator further comprises a first inorganic layer located between the substrate layer and the first electrolyte layer, and The above inorganic particles are a battery located in the above first inorganic layer. In Article 12, The above substrate layer is a battery in contact with the above negative electrode. In Article 1, The first electrolyte layer comprises a cyclic carbonate compound, a linear carbonate compound, or a combination thereof. In Article 14, The above linear carbonate-based compound comprises a battery 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 a battery that is liquid at room temperature. In Article 14, The above-mentioned cyclic carbonate compound comprises 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 a battery that is solid at room temperature. In Article 14, A battery in which the volume (volume%) of the linear carbonate-based compound in the first electrolyte layer is within the range of 5 to 95. In Article 1, The above substrate layer is a battery comprising a polyolefin-based film. In Article 1, The first electrolyte layer comprises a cured product of the first electrolyte composition. In Article 1, A battery further comprising: a second electrolyte layer comprising a second electrolyte composition, wherein the separator is located between the substrate layer and the cathode. In Article 22, The above-mentioned inorganic particles are located in each of the first electrolyte layer and the second electrolyte layer of the battery. In Article 22, The above separator further comprises: a first inorganic layer located between the substrate layer and the first electrolyte layer; and a second inorganic layer located between the substrate layer and the second electrolyte layer. The above inorganic particles are batteries located in each of the first inorganic layer and the second inorganic layer. In Article 24, The above inorganic particles include a first inorganic particle that is flame-retardant and a second inorganic particle that is lithium ion-transmitting, and The first inorganic particle is located in the first inorganic layer, and The above second inorganic particle is a battery located in the above second inorganic layer. In Article 25, The first inorganic particle comprises 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. In Article 25, The above second 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 A battery comprising (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2), or a combination thereof. In Article 1, The above-mentioned first binder comprises a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound. In Article 28, The weight-average molecular weight (g / mol) of the above binder is in the range of 150,000 to 600,000, and A battery in which the second unit content (weight%) of the above binder is within the range of 10 to 25.