Battery separator and battery

Abstract

A battery separator and a battery of the present invention comprise: a substrate layer; an electrolyte layer positioned on one surface or both surfaces of the substrate layer and comprising an electrolyte composition; and inorganic particles, wherein the electrolyte composition contains a binder, a liquid electrolyte, a first crosslinking agent, and a second crosslinking agent, the number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second crosslinking agent, and the electrolyte layer may contain a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound.

Description

Battery separator, and battery

[0001] This document claims the benefit of the priority date of Application No. 10-2024-0188593 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 separator.

[0003] The present invention is a battery.

[0004] 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.

[0005] In some cases, the binder in the gel polymer electrolyte does not dissolve well in the liquid electrolyte. Additionally, the viscosity of the gel polymer electrolyte may increase rapidly during processing. The miscibility between the binder and the liquid electrolyte, as well as the viscosity of the gel polymer electrolyte, can affect the performance of batteries containing the gel polymer electrolyte.

[0006] If a gel polymer electrolyte is included in the electrode active material and the electrode, the wettability to the separator may be reduced.

[0007] To increase the wettability of the separator, a gel polymer electrolyte and a separator can be combined. However, in this case, the gel polymer electrolyte may not be well retained in the polyolefin film. In addition, the interfacial resistance of the gel polymer electrolyte to the adjacent electrode may increase.

[0008] One embodiment of the present invention comprises: a substrate layer; an electrolyte layer located on one or both sides of the substrate layer and comprising an electrolyte composition; and inorganic particles; wherein the electrolyte composition comprises a binder, a liquid electrolyte, a first crosslinking agent, and a second crosslinking agent, the number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second crosslinking agent, and the electrolyte layer comprises a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound.

[0009] The number of crosslinkable functional groups of the first crosslinking agent may be 3 or more.

[0010] The first 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.

[0011] The first crosslinking agent may include a monomeric compound.

[0012] The above-mentioned first 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.

[0013] The number of functional groups of the second crosslinking agent above may be 2.

[0014] The second crosslinking agent may include a di(meth)acrylate-based compound.

[0015] The second crosslinking agent may include a polymeric compound.

[0016] The second crosslinking agent 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.

[0017] The ratio (C1:C2) of the weight of the first crosslinking agent (C1) of the electrolyte layer and the second crosslinking agent (C2) of the electrolyte layer may be in the range of 1:9 to 9:1.

[0018] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0019] The above linear carbonate-based compound may be liquid at room temperature.

[0020] 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.

[0021] The above cyclic carbonate compound may be solid at room temperature.

[0022] The volume (volume%) of the linear carbonate-based compound in the above electrolyte layer may be in the range of 55 to 95.

[0023] The above substrate layer may include a polyolefin-based film.

[0024] The above electrolyte layer may include a cured product of the above electrolyte composition.

[0025] The above inorganic particles may be located in the above electrolyte layer.

[0026] The battery separator further comprises an inorganic layer located between the substrate layer and the electrolyte layer, and the inorganic particles may be located in the inorganic layer.

[0027] The above inorganic particles may include a first inorganic particle capable of lithium ion transfer and a second inorganic particle capable of flame retardancy.

[0028] The above first inorganic particle is Li x Ti y (PO4)3(0 <x<2, 0<y<3), Lix 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.

[0029] The first inorganic particle is a polygonal inorganic particle, and the average size (nm) of the first inorganic particle may be in the range of 100 to 500.

[0030] The second 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.

[0031] The second inorganic particle mentioned above may be a needle-shaped or plate-shaped inorganic particle.

[0032] The second inorganic particle is a needle-shaped inorganic particle, and the average longitudinal length (nm) of the second inorganic particle may be in the range of 300 to 1000, and the average transverse length (nm) of the second inorganic particle may be in the range of 25 to 60.

[0033] The true density of the first inorganic particle is smaller than the true density of the second inorganic particle, the green density of the first inorganic particle is larger than the green density of the second inorganic particle, and the battery separator may contain the first inorganic particle by a greater weight than the second inorganic particle.

[0034] The above binder may include a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound.

[0035] 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.

[0036] The above liquid electrolyte comprises a lithium salt and an additive, wherein the lithium salt comprises LiPF6, LiBF4, LiCl, LiBr, LiI, LiClO4, LiAsF6, LiCH3CO2, LiCF3SO3, LiN(CF3SO2)2, LiN(FSO2)2, LiC(CF2SO2)3, or a combination thereof, and the additive may comprise vinylene carbonate, 1,3-propane sulfone, 1,3-propene sulfone, lithium difluorophosphate, lithium tetrafluoro(oxaleto)phosphate, lithium bis(fluorosulfonylmide), fluoroethylene carbonate, vinyl ethylene carbonate, or a combination thereof.

[0037] Another embodiment of the present invention comprises a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the separator comprises a substrate layer; an electrolyte layer located on one or both sides of the substrate layer and comprising an electrolyte composition; and inorganic particles; wherein the electrolyte composition comprises a binder, a liquid electrolyte, a first crosslinking agent, and a second crosslinking agent, wherein the number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second crosslinking agent, and the electrolyte layer comprises a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound.

[0038] The battery separator of the present invention can maintain the shape of the electrolyte well, increase the wettability of the electrolyte, and lower the resistance to adjacent electrodes.

[0039] The battery of the present invention can simultaneously secure stability and excellent electrochemical performance.

[0040] This document may use ordinal numbers such as "first" and "second" when referring to multiple components. There is no priority among the components.

[0041] 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).

[0042] 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.

[0043] In this document, the numerical range "within the range of A to B" means "A or greater and B or less."

[0044] 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.

[0045] The present document describes the invention in more detail below.

[0046] One embodiment (Embodiment) of the present invention is a battery separator.

[0047] In this document, a battery may include any element that performs an electrochemical reaction.

[0048] 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.

[0049] 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.

[0050] The battery separator of the present invention comprises a substrate layer; an electrolyte layer; and inorganic particles.

[0051] The above substrate layer can cause the fluid to move from one side of the substrate layer to the other.

[0052] 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.

[0053] The above electrolyte layer can provide a path for charge carriers to move to the battery separator.

[0054] 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, and / or impart thermal properties (heat resistance, flame retardancy, etc.).

[0055] The above electrolyte layer comprises an electrolyte composition. The above electrolyte composition may be a composition of a gel polymer electrolyte.

[0056] In this document, the gel polymer electrolyte is an electrolyte in the gel phase and comprises a polymer matrix and a liquid electrolyte impregnated in the polymer matrix. Here, the polymer matrix can physically support the gel polymer electrolyte. The liquid electrolyte can impart ion conductivity to the gel polymer electrolyte.

[0057] In this document, an electrolyte composition refers to a composition that can become an electrolyte either by itself or through a specific reaction.

[0058] The above electrolyte composition includes a binder, a liquid electrolyte, and a crosslinking agent.

[0059] The above binder can form a polymer matrix alone or together with the above crosslinking agents.

[0060] The liquid electrolyte can be impregnated into the polymer matrix formed by the binder. The liquid electrolyte can impart ion conductivity to the gel polymer electrolyte.

[0061] The above crosslinking agents may form a polymer matrix in the gel polymer electrolyte alone or together with the binder. The crosslinking agents may link the binders and / or the crosslinking agents in the polymer matrix.

[0062] The above-mentioned crosslinking agent comprises multiple types of crosslinking agents. Specifically, the above-mentioned crosslinking agent comprises a first crosslinking agent and a second crosslinking agent having different numbers of crosslinkable functional groups. The number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second 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 groups may be functional groups that act to connect binders and / or crosslinking agents in the polymer matrix.

[0063] If the above electrolyte composition includes multiple crosslinking agents having different numbers of crosslinkable functional groups, the electrolyte layer can be formed at a rapid crosslinking rate and can exhibit high crosslinking density and appropriate flexibility.

[0064] Although not limited to theory, it is believed that the excellent characteristics of the above electrolyte layer, such as crosslinking rate, crosslinking density, and flexibility, are due to the fact that the first crosslinking agent can form a dense crosslinking structure and the second crosslinking agent can provide a space for the liquid electrolyte to be impregnated.

[0065] The above liquid electrolyte comprises a non-aqueous solvent. Specifically, the above liquid electrolyte comprises a carbonate compound. More specifically, the above liquid electrolyte comprises a linear carbonate compound and a cyclic carbonate compound.

[0066] 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.

[0067] 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.

[0068] In the above electrolyte composition, the miscibility of the binder with respect to the liquid electrolyte, specifically the miscibility of the binder with respect to the non-aqueous solvent, can affect the processability and structural stability of the battery separator. In addition, it is important that the viscosity of the electrolyte composition is maintained stably, which can be determined by the composition of the non-aqueous solvent.

[0069] In the present invention, the electrolyte layer contains a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound. Specifically, the electrolyte composition contains a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound. Accordingly, the miscibility of the binder with respect to the liquid electrolyte is increased, and an abnormal increase in the viscosity of the electrolyte composition can be prevented.

[0070] Although not limited to theory, it is believed that this is because adjusting the balance between the linear carbonate compound that lowers the viscosity of the composition and the cyclic carbonate compound that raises the viscosity of the composition as described above maintains the viscosity of the composition at an appropriate level while simultaneously ensuring miscibility between the solvent and the binder.

[0071] If the above electrolyte layer contains a linear carbonate-based compound in a volume less than or equal to that of a cyclic carbonate-based compound, the viscosity of the composition increases sharply, and the miscibility between the solvent and the binder also decreases.

[0072] The battery separator of the present invention, comprising a plurality of crosslinking agents with different numbers of crosslinking functional groups and an electrolyte layer comprising a linear carbonate compound in a larger volume than a cyclic carbonate compound, can maintain the shape of the electrolyte well, increase the wettability of the electrolyte, and lower the resistance to adjacent electrodes.

[0073] The above battery separator is described in more detail below.

[0074] The number of crosslinkable functional groups of the first crosslinking agent may be 3 or more. In this case, the first crosslinking agent may form a dense crosslinking structure. Specifically, the number of crosslinkable functional groups of the first crosslinking agent may be 6 or less, 5 or less, or 4 or less.

[0075] 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 crosslinking agent and the above-mentioned second 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.

[0076] Accordingly, the first 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.

[0077] Specifically, the first crosslinking agent may include a triacrylate compound, a tetraacrylate compound, a pentaacrylate compound, a hexaacrylate compound, or a combination thereof.

[0078] More specifically, the first crosslinking agent may include a triacrylate-based compound, a tetraacrylate-based compound, or a combination thereof.

[0079] More specifically, the first crosslinking agent may include a triacrylate-based compound.

[0080] The first 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.

[0081] The above-mentioned first 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.

[0082] Specifically, the first 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, and dipentaerythritol. It may include hexaacrylate, ethoxylated dipentaerythritol hexaacrylate, sorbitol hexaacrylate, or a combination thereof.

[0083] More specifically, the first 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.

[0084] More specifically, the first 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.

[0085] The number of functional groups of the second crosslinking agent may be less than the number of functional groups of the first crosslinking agent. If the number of functional groups of the first crosslinking agent is 3, the number of functional groups of the second crosslinking agent may be 2. If the number of functional groups of the first crosslinking agent is 4, the number of functional groups of the second crosslinking agent may be 2 or 3. If the number of functional groups of the first crosslinking agent is 5, the number of functional groups of the second crosslinking agent may be 2, 3, or 4. If the number of functional groups of the first crosslinking agent is 6, the number of functional groups of the second crosslinking agent may be 2, 3, 4, or 5.

[0086] Specifically, apart from the number of functional groups of the first crosslinking agent, the number of functional groups of the second crosslinking agent may be 2. When the number of functional groups of the second crosslinking agent is as small as possible, the second crosslinking agent may provide a space for the liquid electrolyte to be impregnated.

[0087] The above crosslinking agent may include a photoreactive functional group, specifically a (meth)acryloyl group, and since the number of functional groups of the second crosslinking agent may be 2, the second crosslinking agent may include a di(meth)acrylate-based compound.

[0088] In addition, since it is preferable that the photoreactive functional group includes an acryloyl group, the second crosslinking agent may include a diacrylate-based compound.

[0089] The second crosslinking agent may include a polymeric compound. The polymeric crosslinking agent may mean that the remaining moiety, excluding the crosslinking functional group, is of polymeric origin.

[0090] Preferably, the first crosslinking agent comprises a monomeric compound, and the second 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, superior properties such as the crosslinking rate, crosslinking density, and flexibility of the electrolyte layer can be more appropriately exhibited.

[0091] The second crosslinking agent 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.

[0092] Specifically, the second crosslinking agent may include polyethylene glycol diacrylate, poly(ethylene oxide-propylene oxide) diacrylate, polyurethane diacrylate, polycarbonate diacrylate, or a combination thereof.

[0093] More specifically, the second crosslinking agent may include polyethylene glycol diacrylate, polyurethane diacrylate, or a combination thereof.

[0094] More specifically, the second crosslinking agent may include polyurethane diacrylate.

[0095] When the second crosslinking agent comprises a polymeric compound, the molecular weight of the polymeric compound may also be controlled. The second crosslinking agent may comprise 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 second crosslinking agent may comprise polyurethane diacrylate with a molecular weight in the range of 1400 g / mol to 2100 g / mol.

[0096] The mixing ratio of the first crosslinking agent and the second crosslinking agent can also be appropriately adjusted.

[0097] The ratio (C1:C2) of the weight of the first crosslinking agent (C1) of the electrolyte layer and the second crosslinking agent (C2) of the electrolyte layer may be in the range of 1:9 to 9:1.

[0098] Preferably, the ratio (C1:C2) of the weight of the first crosslinking agent (C1) of the electrolyte layer and the weight of the second crosslinking agent (C2) of the 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:C2) of the weight of the first crosslinking agent (C1) of the electrolyte layer and the second crosslinking agent (C2) of the 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.

[0099] The weight of the crosslinking agent in the above electrolyte layer can be controlled by the weight of the crosslinking agent in the above electrolyte composition.

[0100] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0101] Specifically, the linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0102] More specifically, the linear carbonate-based compound may include ethylmethyl carbonate.

[0103] The above linear carbonate-based compound may be liquid at room temperature.

[0104] 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.

[0105] Specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0106] More specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

[0107] From the perspective of the miscibility of the aforementioned binder and liquid electrolyte, the control of the viscosity of the electrolyte 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.

[0108] The above cyclic carbonate-based compound may be solid at room temperature. Specifically, the above cyclic carbonate-based compound may include ethylene carbonate.

[0109] 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.

[0110] The volume (volume%) of the linear carbonate-based compound in the above electrolyte layer may be in the range of 55 to 95.

[0111] 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.

[0112] The volume (volume%) of the cyclic carbonate-based compound in the above electrolyte layer may be in the range of 5 to 45.

[0113] 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.

[0114] The volume of the linear carbonate-based compound and the volume of the cyclic carbonate-based compound in the electrolyte layer can be controlled to the volume of the linear carbonate-based compound and the volume of the cyclic carbonate-based compound of the electrolyte composition.

[0115] The above substrate layer may include a polyolefin-based film. Specifically, the above substrate layer may include a porous polyolefin-based film.

[0116] Here, a polyolefin-based porous film refers to a porous film containing a polyolefin-based resin as a main component.

[0117] 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.

[0118] The weight average molecular weight of the component included in the above polyolefin resin is 3×10 5 Up to 15X10 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] The above curing method may include, for example, thermal curing, photocuring, and thermal-photo dual curing. Preferably, the curing method may be photocuring.

[0123] 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.

[0124] The above-mentioned inorganic particles may exist in various forms in the battery separator.

[0125] The inorganic particles may be located in the electrolyte layer. Specifically, the electrolyte composition may further include the inorganic particles. When the electrolyte composition is cured, the inorganic particles may be located in the electrolyte layer. At this time, the electrolyte layer may come into direct contact with the substrate layer. There may not be a separate layer between the electrolyte layer and the substrate layer.

[0126] The above inorganic particles may exist as a separate layer from the substrate layer and the electrolyte layer in the battery separator.

[0127] The battery separator may further include an inorganic layer located between the substrate layer and the electrolyte layer. In this case, the inorganic particles may be located in the inorganic layer. In this case, the electrolyte layer or the electrolyte composition may not contain inorganic particles.

[0128] 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.

[0129] 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 first inorganic particle capable of lithium ion transfer and a second inorganic particle capable of flame retardancy.

[0130] 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.

[0131] 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 It may include (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2), or a combination thereof. Preferably, the first inorganic particle is Li xAl y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3)를 포함할 수 있다.

[0132] The first inorganic particle mentioned above may be a polygonal inorganic particle.

[0133] In this document, a polygonal particle may refer to a polyhedral particle whose outer edge is composed of several straight lines. When the maximum length, maximum width, and maximum thickness of the polygonal particle are L, W, and T, respectively, L / W and W / T may each be within the range of 1 to 3. The shape of the polyhedron constituting the polygonal particle is not particularly limited. The polygonal particle may be a particle having a polyhedral shape that satisfies the conditions of L, W, and T described above.

[0134] The average size (nm) of the first inorganic particle may be in the range of 100 to 500. Preferably, the average size (nm) of the first inorganic particle may be 150 or more, 200 or more, 250 or more, 300 or more, 310 or more, 320 or more, 324 or more, or 330 or more. The average size (nm) of the first inorganic particle may be 450 or less, 400 or less, 350 or less, or 340 or less.

[0135] The average size of the first inorganic particles may refer to the average of the maximum lengths of each particle. The average size of the first inorganic particles may be measured using known particle size analysis equipment. Additionally, the average size of the first inorganic particles may be measured using electron microscope images of the first inorganic particles. The average of the number of inorganic particles with maximum lengths identified in the electron microscope images may be the average size of the first inorganic particles.

[0136] 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.

[0137] The second 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 second inorganic particle may include ZrO2, Y2O3, Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof. More preferably, the second inorganic particle may include Al2O3, AlOOH, Al(OH)3, TiO2, or a combination thereof.

[0138] The second inorganic particle may be a polygonal inorganic particle, an acicular inorganic particle, or a plate-shaped inorganic particle. Preferably, the second inorganic particle may be an acicular inorganic particle or a plate-shaped inorganic particle.

[0139] In this document, needle-shaped particles may refer to particles that are long and thin like needles or fibers, with a length that is very long compared to their thickness or width. When the maximum length, maximum width, and maximum thickness of the needle-shaped particles are L, W, and T, respectively, L / W or L / T may be 3 or greater.

[0140] In this document, plate-shaped particles may refer to particles that are flat like a plate because their thickness is very thin compared to their length or width. When the maximum length, maximum width, and maximum thickness of the plate-shaped particles are L, W, and T, respectively, L / T or W / T may be 3 or greater.

[0141] Preferably, the second inorganic particle is a needle-shaped particle, and the transverse length and longitudinal length of the second inorganic particle can each be adjusted. The longitudinal length of the second inorganic particle may be longer than the transverse length of the second inorganic particle.

[0142] The average longitudinal length (nm) of the second inorganic particle may be in the range of 300 to 1000. The average transverse length (nm) of the second inorganic particle may be in the range of 25 to 60.

[0143] Preferably, the average longitudinal length (nm) of the second inorganic particle may be 350 or more, 400 or more, 450 or more, 500 or more, 550 or more, 597 or more, or 600 or more. The average longitudinal length (nm) of the second inorganic particle may be 900 or less, 800 or less, 700 or less, 650 or less, or 600 or less.

[0144] Preferably, the average transverse length (nm) of the second inorganic particle may be 30 or more, 35 or more, 40 or more, 45 or more, or 49 or more. The average transverse length (nm) of the second inorganic particle may be 55 or less, 51 or less, or 50 or less.

[0145] The longitudinal length of the second inorganic particle may refer to the maximum length of the second inorganic particle. The transverse length of the second inorganic particle may refer to the longer length among the dimensions measured in a direction orthogonal to the longitudinal direction.

[0146] The average longitudinal length of the second inorganic particle can be measured using an electron microscope image of the second inorganic particle. The average of the number of inorganic particles with the maximum length of each second inorganic particle identified in the electron microscope image may be the average longitudinal length of the second inorganic particle. Additionally, the average of the number of inorganic particles with a length perpendicular to the maximum length of each second inorganic particle measured in the electron microscope image may be the average transverse length of the second inorganic particle.

[0147] The true density of the first inorganic particle may be lower than the true density of the second inorganic particle. The inorganic particles can improve the mechanical and thermal properties of the battery separator by imparting rigidity and heat resistance to the battery separator. If the battery separator contains multiple inorganic particles with different densities, the heavier particles can form a framework at the bottom, while the lighter particles can fill the gaps formed by the heavier particles or at the top; in this process, a uniform pore structure can be formed inside the battery separator. A uniform pore structure can increase the electrolyte impregnation and ion conductivity of the battery separator.

[0148] In this document, a uniform pore structure may refer to a structure in which the average size, shape, and density of the pores are nearly constant regardless of the position of the layer, thereby maintaining a constant material transport path within it. A uniform pore structure may refer to a state in which the variation in the size distribution and spatial distribution of the pores is small throughout the battery separator containing the pores, the pores are continuously connected to one another, and the pores are not localized in a specific direction or position.

[0149] In this document, the true density of a particle may refer to the density calculated solely from the mass and volume of the particle itself, excluding voids within the particle. The true density of the inorganic particle may be a known value for the inorganic particle or a value measured according to known methods. The true density of the inorganic particle may be determined by the chemical composition of the inorganic particle.

[0150] True density (g / cm²) of the first inorganic particle above 3 ) may be in the range of 1 to 3. Preferably, the true density (g / cm³) of the first inorganic particle is 3 ) may be 1.3 or more, 1.5 or more, 2.0 or more, or 2.3 or more. The true density (g / cm³) of the first inorganic particle above. 3) may be 2.7 or less, 2.5 or less, or 2.4 or less.

[0151] True density (g / cm²) of the above second inorganic particle 3 ) may be in the range of 2 to 5. The true density (g / cm³) of the second inorganic particle is 3 ) may be 2.3 or higher, 2.5 or higher, 2.7 or higher, or 3.0 or higher. The true density (g / cm³) of the second inorganic particle above. 3 ) may be 4.7 or less, 4.5 or less, 4.0 or less, 3.5 or less, or 3.1 or less.

[0152] The green density of the first inorganic particle may be greater than the green density of the second inorganic particle.

[0153] In this document, the green density of the particles (compact density) may refer to the density of the particles in a state where they have been processed into a compact of a predetermined shape. The green density is a density that reflects not only the density of the particles themselves but also the voids between the particles. The method for measuring the green density of the inorganic particles is described in detail in the examples.

[0154] That is, in the battery separator, heavier inorganic particles can be arranged less densely, and lighter inorganic particles can be arranged more densely. As a result, a structure can be formed in which the heavier inorganic particles fill the pores formed by the lighter inorganic particles. When pores with a uniform distribution are formed in the battery separator, the amount of electrolyte impregnated into the battery separator can be increased. As a result, the ion conductivity of the battery separator can be increased.

[0155] Green density (g / cm³) of the first inorganic particle above 3 ) may be in the range of 1 to 3. Preferably, the green density (g / cm³) of the first inorganic particle is green. 3 ) may be 1.1 or higher, 1.2 or higher, 1.3 or higher, or 1.4 or higher. The green density (g / cm³) of the first inorganic particle above. 3) may be 2.5 or less, 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, or 1.5 or less.

[0156] Green density (g / cm²) of the above second inorganic particle 3 ) may be in the range of 1 to 3. Preferably, the green density (g / cm³) of the second inorganic particle is green. 3 ) may be 1.05 or higher, 1.10 or higher, or 1.15 or higher. Green density (g / cm³) of the second inorganic particle. 3 ) may be 2.5 or less, 2.0 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, or 1.17 or less.

[0157] The content ratio of the first inorganic particle and the second inorganic particle in the battery separator can be determined by considering the role of each particle. The battery separator may contain the first inorganic particle in a greater weight than the second inorganic particle.

[0158] The content of the second inorganic particle of the battery separator (weight%) based on the total sum of the first inorganic particle and the second inorganic particle may be 5 or more. The content of the second inorganic particle of the battery separator (weight%) based on the total sum of the first inorganic particle and the second inorganic particle may be 10 or more, 15 or more, 20 or more, 25 or more, or 30 or more. The content of the second inorganic particle of the battery separator (weight%) based on the total sum of the first inorganic particle and the second inorganic particle may be 50 or less, 45 or less, 40 or less, 35 or less, or 30 or less.

[0159] The relationship between the true density of the first inorganic particle and the second inorganic particle can be determined according to the chemical composition of the compounds constituting the first inorganic particle and the second inorganic particle.

[0160] The green density relationship between the first inorganic particle and the second inorganic particle can be determined according to the shape and size of the first inorganic particle and the second inorganic particle, respectively. As previously mentioned, the shape of the first inorganic particle may differ from the shape of the second inorganic particle.

[0161] The binder can form a framework in the electrolyte layer formed by the 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] The weight average molecular weight of the above fluorine-based binder can be measured by gel permeation chromatography.

[0171] 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.

[0172] The liquid electrolyte may be impregnated into the binder, specifically the polymer matrix formed by the binder. The liquid electrolyte may further include a lithium salt and an additive. The lithium salt may be dissolved in the non-aqueous solvent.

[0173] The above lithium salt may refer to a material that decomposes into lithium cations and anions upon dissociation.

[0174] 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.

[0175] 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.

[0176] 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.

[0177] 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. When the electrolyte layer is located on both sides of the substrate layer, the thickness of the electrolyte layer refers to the thickness per layer.

[0178] The above electrolyte composition may further include an initiator.

[0179] When a predetermined stimulus is applied, the initiator can initiate a reaction in which the binder forms a polymer matrix.

[0180] The above initiator may include a thermal polymerization initiator, a photopolymerization initiator, or a combination thereof. Preferably, the initiator may include a photopolymerization initiator.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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 stage.

[0186] The above UV curing method may include the following steps. The number of each step does not indicate the order of the steps:

[0187] (1) Prepare the above electrolyte composition;

[0188] (2) Applying the electrolyte composition to one or both sides of the substrate layer; and

[0189] (3) Irradiate the above electrolyte composition with UV.

[0190] 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.

[0191] Conditions such as the application method and thickness of the above electrolyte composition are not particularly limited.

[0192] The conditions of UV irradiation on the above electrolyte composition are not particularly limited.

[0193] Another embodiment of the present invention is a battery.

[0194] 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).

[0195] The system comprising the separator and electrolyte of the above-mentioned battery may be the battery separator of the present invention. Accordingly, the description regarding the separator and electrolyte in the description of the battery can be entirely replaced by the aforementioned battery separator.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] Among the 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. Preferably, the negative electrode active material may include a carbon-based compound.

[0200] 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.

[0201] 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.

[0202] The present invention is described in more detail below through examples and comparative examples. However, the present invention is not limited to the examples.

[0203] [manufacturing]

[0204] Example 1. Battery separator

[0205] A battery separator was manufactured according to the following process.

[0206] (1) Prepare a dispersion by dispersing a mixture of 7 g of first inorganic particles and 3 g of second inorganic particles in 20 g of water. The first inorganic particles are LATP 300 from Zhejinag Fun Lithium New Energy Technology (polygonal Li 1.3 Al 0.3 Ti 1.7 P3O 12 True density: 2.3 g / cm³ 3 Green density: 1.42 g / cm³ 3 ; Average size: 324 nm). The second inorganic particle is Aramis' NNB (acicular boehmite; true density: 3.03 g / cm³). 3 Green density: 1.15 g / cm³ 3 ; Average longitudinal length: 597 nm; Average longitudinal length: 49 nm)

[0207] (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%).

[0208] (3) Apply the above slurry to the upper and lower surfaces of the substrate layer using a dual slot die and dry it to produce a structure with a total thickness of 10 μm, in which inorganic layers are located on both sides of the substrate layer. The substrate layer is Asahi Kasei ND408A (PE film; thickness: 8 μm; porosity: 38%).

[0209] (4) Prepare a solution by adding 5 g of binder, 8 g of first crosslinking agent, and 2 g of second crosslinking agent to 85 g of liquid electrolyte, and then mix the solution with a homogenizer, and then add 0.02 g of photopolymerization initiator to the solution to prepare an electrolyte composition with a solid content of 15 wt%. 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 M300 (trimethylolpropane triacrylate). 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 LiPF6 is dissolved, and 2% of vinylene carbonate (VC) is added by weight.

[0210] (5) Apply the electrolyte composition to the upper and lower surfaces of the structure on which the above-mentioned inorganic layer is located using a dual slot die and cure it with UV irradiation to produce a battery separator with a total thickness of 50 μm.

[0211] Example 2. Battery separator

[0212] A battery separator was prepared by repeating the same process as in Example 1, except that 6 g of the first crosslinking agent and 4 g of the second crosslinking agent were added in (4) above.

[0213] Example 3. Battery separator

[0214] A battery separator was prepared by repeating the same process as in Example 1, except that 4 g of the first crosslinking agent and 6 g of the second crosslinking agent were added in (4) above.

[0215] Example 4. Battery separator

[0216] A battery separator was manufactured by repeating the same process as in Example 1, except that PU5000 (polyurethane diacrylate; weight average molecular weight: 1800) from Miwon Specialty Chemicals was used as the second crosslinking agent in (4) above.

[0217] Example 5. Battery separator

[0218] A battery separator was manufactured by repeating the same process as in Example 1, except that M340 (pentaerythritol triacrylate; PETA) from Miwon Specialty Chemicals was used as the first crosslinking agent in (4) above.

[0219] Comparative Example 1. Battery separator

[0220] A battery separator was prepared by repeating the same process as in Example 1, except that 10 g of the first crosslinking agent was added in (4) above and the second crosslinking agent was not added.

[0221] Comparative Example 2. Battery Separator

[0222] A battery separator was prepared by repeating the same process as in Example 1, except that 10 g of the second crosslinking agent was added in (4) above and the first crosslinking agent was not added.

[0223] Comparative Example 3. Battery Separator

[0224] A battery separator was prepared by repeating the same process as in Example 1, except that 5 g of the first crosslinking agent and 5 g of the second crosslinking agent were added in (4) above, and M340 (pentaerythritol triacrylate; PETA) from Miwon Specialty Chemical was used as the second crosslinking agent.

[0225] Comparative Example 4. Battery Separator

[0226] A battery separator was prepared by repeating the same process as in Example 1, except that 5 g of the first crosslinking agent and 5 g of the second crosslinking agent were added in (4) above, and Miramer M284 (polyethylene glycol diacrylate; weight average molecular weight: 408 g / mol) from Miwon Specialty Chemicals was used as the first crosslinking agent.

[0227] [evaluation]

[0228] Experimental Example 1. Shape of inorganic particles

[0229] The shape and size of the inorganic particles used in the examples and comparative examples were confirmed by SEM images. The capture of the SEM images was carried out through the following process.

[0230] (1) Prepare a dispersion by dispersing inorganic particles at a concentration of 5 wt% in ethanol by ultrasonic treatment (using Lab Companion’s UCP-10, 300 W, 40 kHz, 10 min, 25 ℃).

[0231] (2) Apply 1 mL of dispersion onto a substrate film (36 μm PET) using a dropper and dry it in a convection oven (no nitrogen or vacuum treatment, 80 ℃, 10 min).

[0232] (3) Attach the dried film to the holder of the SEM equipment (FESEM-JSM7610F-plus, JEOL) using carbon tape (T01-215-015 of NISSHIN EM Co., Ltd).

[0233] (4) Take a photograph with SEM equipment (acceleration voltage: 5 kV, working distance: 8.3~8.5 mm, SEM mode, magnification: 30,000 or 50,000).

[0234] (5) Determine the shape of the inorganic particles identified in the acquired SEM images using IMAGE J software in the following way. 50 inorganic particles are selected per SEM image.

[0235] 1) Acicular particles: Those where L / W or L / T is 3 or greater, given that the maximum length, maximum width, and maximum thickness are L, W, and T, respectively.

[0236] 2) Plate-shaped particles: When the maximum length, maximum width, and maximum thickness of the particles are L, W, and T, respectively, L / T or W / T is 3 or greater.

[0237] 3) Polygonal particle: When the maximum length, maximum width, and maximum thickness are L, W, and T, respectively, L / W and W / T are each within the range of 1 to 3.

[0238] (6) Measure the size of inorganic particles identified in the acquired SEM images using IMAGE J software in the following manner. 50 inorganic particles are selected per SEM image.

[0239] 1) Needle-shaped or plate-shaped particles: The average longitudinal length is determined as the average of the number of inorganic particles with the maximum length of each inorganic particle. The average transverse length is determined as the average of the number of inorganic particles with the length in the direction perpendicular to the maximum length of each inorganic particle.

[0240] 2) Polygonal particles: The average size is determined by the average of the number of inorganic particles with the maximum length of each inorganic particle.

[0241] Experimental Example 2. Green density of inorganic particles

[0242] The green density of inorganic particles was measured according to the following process.

[0243] (1) Pre-treat inorganic particles by vacuum drying (80 ℃, 6 hours) followed by aging (25 ℃, 7 days).

[0244] (2) Place 1 g of pretreated inorganic particles into a cylindrical mold with a diameter of 16 mm.

[0245] (3) Next, in the above cylindrical mold, 1 ton / cm under the following conditions 2To produce a specimen in the form of a compacted pellet (green pellet) by applying pressure.

[0246] Pressure application equipment: Carver hydraulic press 4386,

[0247] Applying load holding time: 30 seconds

[0248] Compression count: 1 time

[0249] (4) Measure the thickness of the center of the specimen three times using Mitutoyo’s CD-15APX and determine the volume of the specimen using the average value.

[0250] (5) Calculate the green density of the inorganic particles using the volume of the specimen and the weight (1 g) of the specimen measured in (4) above.

[0251] Experimental Example 3. Resistance and Ionic Conductivity

[0252] The resistance and ionic conductivity of the battery separator were evaluated according to the following process.

[0253] (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)

[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 4. Battery Performance

[0256] The discharge capacity and capacity retention rate of the battery manufactured using the battery separator were measured through the following process.

[0257] (1) The battery separator is stamped to a size of 32 mm x 44 mm.

[0258] (2) bipolar

[0259] 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).

[0260] 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.

[0261] 3) Die the above anode plate into a size of 30 mm x 42 mm.

[0262] (2) Negative electrode

[0263] 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.

[0264] 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.

[0265] 3) Die the above cathode plate into a size of 31 mm x 43 mm.

[0266] (3) Assembly

[0267] 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 composite electrolyte is placed between the positive active material layer and the negative active material layer.

[0268] 2) Place this electrode assembly in a pouch and inject an electrolyte into it to complete the battery. The electrolyte is the same as that used in the preparation of the electrolyte composition. Five battery samples were prepared. The performance of the battery is the arithmetic mean of the five samples.

[0269] (4) Perform charge and discharge cycles of the battery. The conditions for the repeated charge and discharge test are room temperature, 2.5°C, and 0.1°C-rate.

[0270] (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.

[0271] [Results and Discussion]

[0272] Table 1 below shows the test results of the examples and comparative examples.

[0273] Example Comparative Example 1 2345 1234 Resistance Ohm 1.03 1.01 0.96 1.00 1.08 1.53 1.1 1.67 X Ionic Conductivity mS / cm 2.4 1 2.46 2.59 2.36 2.31 1.66 2.26 1.49 X Charge / Discharge Cycle Test 1st Cycle Charge Capacity mAh / g 42.64 1.73 8.94 2.34 2.53 8.83 5.24 0.1 X Discharge Capacity mAh / g 42.94 2.14 2.24 0.94 1.44 1.64 1.13 4.8 X 10th Cycle Cycle Charge Capacity mAh / g 42.0 40.7 37.5 42.0 42.3 36.3 32.0 36.5X Discharge Capacity mAh / g 42.4 41.8 40.9 40.6 41.2 39.5 35.9 31.7X Discharge Capacity Retention Rate % 98.6 97.6 96.4 96.7 97.4 93.6 90.9 86.8XX: Physical properties cannot be measured due to non-formation of gel

Claims

Base layer; An electrolyte layer located on one or both sides of the above substrate layer and comprising an electrolyte composition; and Inorganic particles; Includes, The above electrolyte composition comprises a binder, a liquid electrolyte, a first crosslinking agent, and a second crosslinking agent, and The number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second crosslinking agent, and The above electrolyte layer is a battery separator containing a linear carbonate compound in a larger volume than a cyclic carbonate compound. In Article 1, A battery separator having three or more crosslinkable functional groups of the first crosslinking agent. In Article 1, The above-mentioned first 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, for a battery separator. In Article 1, The above first crosslinking agent is a battery separator comprising a monomeric compound. In Article 1, The above-mentioned first 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, or a combination thereof. In Article 1, A battery separator having 2 functional groups of the second crosslinking agent. In Article 1, The above second crosslinking agent is a battery separator comprising a di(meth)acrylate-based compound. In Article 1, The above second crosslinking agent is a battery separator comprising a polymeric compound. In Article 1, The above second crosslinking agent comprises a battery separator comprising 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 separator in which the ratio (C1:C2) of the weight of the first crosslinking agent (C1) of the electrolyte layer and the second crosslinking agent (C2) of the electrolyte layer is within the range of 1:9 to 9:

1. In Article 1, The above linear carbonate-based compound is a battery separator comprising dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof. In Article 1, The above linear carbonate-based compound is a battery separator that is liquid at room temperature. In Article 1, The above-mentioned cyclic carbonate compound is a battery separator 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 1, The above-mentioned cyclic carbonate-based compound is a battery separator that is solid at room temperature. In Article 1, A battery separator in which the volume (volume%) of the linear carbonate-based compound in the above electrolyte layer is within the range of 55 to 95. In Article 1, The above substrate layer is a battery separator comprising a polyolefin-based film. In Article 1, The above electrolyte layer is a battery separator comprising a cured product of the above electrolyte composition. In Article 1, The above-mentioned inorganic particles are a battery separator located in the above-mentioned electrolyte layer. In Article 1, Further comprising an inorganic layer located between the above substrate layer and the above electrolyte layer, The above inorganic particles are a battery separator located in the above inorganic layer. In Article 1, The above-mentioned inorganic particles are a battery separator comprising a first inorganic particle capable of lithium ion transfer and a second inorganic particle capable of flame retardancy. In Article 20, 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 A battery separator comprising (0≤x≤1, 0≤y≤0.5, 0≤z≤0.2), or a combination thereof. In Article 20, The first inorganic particle mentioned above is a polygonal inorganic particle, and A battery separator in which the average size (nm) of the first inorganic particles is within the range of 100 to 500. In Article 20, The above second inorganic particle comprises a battery separator comprising 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 20, The above second inorganic particle is a battery separator that is a needle-shaped or plate-shaped inorganic particle. In paragraph 20, The above-mentioned second inorganic particle is a needle-shaped inorganic particle, and The average longitudinal length (nm) of the second inorganic particle is in the range of 300 to 1000, and A battery separator in which the average transverse length (nm) of the second inorganic particle is within the range of 25 to 60. In Article 20, The true density of the first inorganic particle is smaller than the true density of the second inorganic particle, and The green density of the first inorganic particle is greater than the green density of the second inorganic particle, and The above battery separator is a battery separator containing a first inorganic particle by a greater weight than a second inorganic particle. 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 27, 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 27, The above liquid electrolyte includes a lithium salt and an additive, and The above lithium salt includes LiPF6, LiBF4, LiCl, LiBr, LiI, LiClO4, LiAsF6, LiCH3CO2, LiCF3SO3, LiN(CF3SO2)2, LiN(FSO2)2, LiC(CF2SO2)3, or a combination thereof, and The above additive is a battery separator comprising 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. It includes an anode, a cathode, and a separator located between the anode and the cathode, and The above separator comprises: a substrate layer; an electrolyte layer located on one or both sides of the substrate layer and comprising an electrolyte composition; and inorganic particles. The above electrolyte composition comprises a binder, a liquid electrolyte, a first crosslinking agent, and a second crosslinking agent, and The number of crosslinkable functional groups of the first crosslinking agent is greater than the number of crosslinkable functional groups of the second crosslinking agent, and The above electrolyte layer is a battery containing a linear carbonate compound in a larger volume than a cyclic carbonate compound.