Battery separator and battery

Abstract

A battery separator and a battery of the present invention comprise: a substrate layer; a first electrolyte layer disposed on one surface of the substrate layer and including a first electrolyte composition; a second electrolyte layer disposed on the other surface of the substrate layer and including a second electrolyte composition; and inorganic particles, wherein the solid content (wt%) of the first electrolyte composition may be greater than the solid content (wt%) of the second electrolyte composition.

Description

Battery separator, and battery

[0001] This document claims the benefit of the priority date of Application No. 10-2024-0188592 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] A lithium metal battery is a battery that contains lithium metal as the negative electrode active material.

[0006] 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.

[0007] One embodiment of the present invention is a battery separator comprising: a substrate layer; a first electrolyte layer located on one side of the substrate layer and comprising a first electrolyte composition; a second electrolyte layer located on the other side of the substrate layer and comprising a second electrolyte composition; and inorganic particles, wherein the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

[0008] 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.

[0009] The first electrolyte composition comprises a first binder, a first liquid electrolyte, and a first crosslinking agent, and the second electrolyte composition comprises a second binder, a second liquid electrolyte, and a second crosslinking agent, and the content of the first liquid electrolyte (weight%) of the first electrolyte composition may be less than the content of the second liquid electrolyte (weight%) of the second electrolyte composition.

[0010] The first binder and the second binder may each independently comprise a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound.

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

[0012] The first liquid electrolyte and the second liquid electrolyte may each independently include a non-aqueous solvent, a lithium salt, and an additive.

[0013] The first crosslinking agent comprises a first-1 crosslinking agent and a first-2 crosslinking agent, and the second crosslinking agent comprises a second-1 crosslinking agent and a second-2 crosslinking agent, wherein 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, and the number of crosslinkable functional groups of the second-1 crosslinking agent may be greater than the number of crosslinkable functional groups of the second-2 crosslinking agent.

[0014] The above-mentioned 1-1 crosslinking agent and the above-mentioned 2-1 crosslinking agent may each independently include a monomeric compound.

[0015] The number of crosslinkable functional groups of the above 1-1 crosslinking agent and the number of crosslinkable functional groups of the above 2-1 crosslinking agent may each be independently 3 or more.

[0016] The above 1-1 crosslinking agent and the above 2-1 crosslinking agent may each independently 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.

[0017] The above 1-1 crosslinking agent and the above 2-1 crosslinking agent are each independently 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, It may include ditrimethylolpropane tetra(meth)acrylate, 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.

[0018] The above first-2 crosslinking agent and the above second-2 crosslinking agent may each independently include a polymeric compound.

[0019] The number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may be 2.

[0020] The above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent may each independently include a di(meth)acrylate-based compound.

[0021] The above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent may each independently 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.

[0022] The ratio (C1-1:C1-2) of the weight of the 1-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the 1-2 crosslinking agent (C1-2) of the first electrolyte layer, and the ratio (C2-1:C2-2) of the weight of the 2-1 crosslinking agent (C2-1) of the second electrolyte layer and the weight of the 2-2 crosslinking agent (C2-2) of the second electrolyte layer, may each independently be within the range of 1:9 to 9:1.

[0023] The first electrolyte layer and the second electrolyte layer may each independently contain a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound.

[0024] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0025] The above linear carbonate-based compound may be liquid at room temperature.

[0026] 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.

[0027] The above cyclic carbonate compound may be solid at room temperature.

[0028] The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer and the volume (volume%) of the linear carbonate-based compound in the second electrolyte layer may each independently be within the range of 55 to 95.

[0029] The above substrate layer may include a polyolefin-based film.

[0030] The first electrolyte layer comprises a cured product of the first electrolyte composition, and the second electrolyte layer may comprise a cured product of the second electrolyte composition.

[0031] The above inorganic particles may be located in the first electrolyte layer and the second electrolyte layer.

[0032] It further includes 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; wherein the inorganic particles may be located in the first inorganic layer and the second inorganic layer.

[0033] The above inorganic particles may include a first inorganic particle capable of lithium ion transfer and a second inorganic particle capable of flame retardancy.

[0034] The above first inorganic particle is Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Tiz (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.

[0035] 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.

[0036] 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.

[0037] The second inorganic particle mentioned above may be a needle-shaped or plate-shaped inorganic particle.

[0038] 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.

[0039] 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.

[0040] 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; a first electrolyte layer located on one side of the substrate layer and comprising a first electrolyte composition; a second electrolyte layer located on the other side of the substrate layer and comprising a second electrolyte composition; and inorganic particles; wherein the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

[0041] The above-mentioned cathode comprises lithium metal, the first electrolyte layer may be located adjacent to the cathode, and the second electrolyte layer may be located adjacent to the anode.

[0042] One side of the battery separator of the present invention can buffer external physical stimuli, and the other side can increase ion conductivity.

[0043] 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.

[0044] This document may use ordinal numbers such as "first" and "second" when referring to multiple components. There is no priority among the components.

[0045] 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).

[0046] 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.

[0047] In this document, the numerical range "within the range of A to B" means "A or greater and B or less."

[0048] 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.

[0049] The present document describes the invention in more detail below.

[0050] One embodiment (Embodiment) of the present invention is a battery separator.

[0051] In this document, a battery may include any element that performs an electrochemical reaction.

[0052] 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.

[0053] 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.

[0054] The battery separator of the present invention comprises a substrate layer, a first electrolyte layer, a second electrolyte layer; and inorganic particles.

[0055] The above substrate layer can cause the fluid to move from one side of the substrate layer to the other.

[0056] The first electrolyte layer is located on one side of the substrate layer. The second electrolyte layer is located on the other side of the substrate layer facing the one side. Specifically, the first electrolyte layer may be located on the first side of the substrate layer, and the second electrolyte layer may be located on the first side of the substrate layer and on the second side facing the first side. The composition and thickness of the first electrolyte layer and the second electrolyte layer may be the same or different.

[0057] The first electrolyte layer and the second electrolyte layer can provide a path for a charge carrier to move to the battery separator.

[0058] 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.).

[0059] 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.

[0060] 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.

[0061] In this document, an electrolyte composition refers to a composition that can become an electrolyte either by itself or through a specific reaction.

[0062] In the present invention, the first electrolyte layer and the second electrolyte layer exhibit different physical properties. Through this, the battery separator of the present invention can balance the positive and negative electrodes, particularly in batteries where the positive and negative electrodes exhibit different characteristics.

[0063] 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.

[0064] In contrast, the stiffness of the electrolyte layer may exhibit a relationship opposite to that of the 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.

[0065] Although not limited to theory, it is believed that this is because the second electrolyte layer contains a larger amount of liquid electrolyte compared to the first electrolyte layer. Additionally, it is also believed that this is because the contactability of the second electrolyte layer with respect to adjacent electrodes is superior to that of the first electrolyte.

[0066] 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.

[0067] Accordingly, the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

[0068] One side of the battery separator of the present invention, in which two electrolyte layers with opposite characteristics are arranged to face each other in a substrate layer, can buffer external physical stimuli, and the other side can increase the ion conductivity of the battery. Therefore, the battery separator of the present invention may be particularly suitable for batteries requiring opposite characteristics for the positive and negative electrodes.

[0069] For example, the negative electrode of a lithium metal battery containing lithium metal as the negative electrode may expand during the charging and discharging process, potentially causing cracks in the positive electrode. In this case, the first electrolyte layer of the battery separator of the present invention may be located on the negative electrode side, and the second electrolyte layer may be located on the positive electrode side. The expansion of the negative electrode by the first electrolyte layer can be suppressed, and even if the negative electrode expands, the resulting problems can be mitigated due to the buffering properties of the first electrolyte layer. Furthermore, since the second electrolyte layer is positioned adjacent to the positive electrode to further increase ion conductivity, the decrease in ion conductivity caused by cracks in the positive electrode due to the expansion of the negative electrode can be reduced.

[0070] The solid content of the above electrolyte composition may refer to the ratio of the total weight of the remaining components, excluding the liquid electrolyte, to the weight of the composition. Specifically, the solid content of the above electrolyte composition may be a value converted into a percentage by dividing the weight of the dried 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.

[0071] 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.

[0072] Hereinafter, this document describes the battery separator of the present invention in more detail.

[0073] The solid content (SC1, weight%) of the first electrolyte composition may be in the range of 30 to 60. Preferably, the solid content (SC1, weight%) of the first electrolyte composition may be 35 or more, 37.4 or more, 38.4 or more, 38.6 or more, 40 or more, or 41.2 or more. The solid content (SC1, weight%) of the first electrolyte composition may be 55 or less, 50 or less, 45 or less, or 42 or less.

[0074] The solid content (SC2, weight%) of the second electrolyte composition may be in the range of 10 to 50. Preferably, the solid content (SC2, weight%) of the second electrolyte composition may be 15 or more, 20 or more, 24.2 or more, 25 or more, 27.5 or more, 28.1 or more, or 30 or more. The solid content (SC2, weight%) of the second electrolyte composition may be 45 or less, 40 or less, 35 or less, or 31 or less.

[0075] 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 electrolyte composition and the solid content of the second electrolyte composition can be considered the same.

[0076] 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.

[0077] Preferably, 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 1.1 or more, 1.15 or more, 1.20 or more, 1.25 or more, 1.30 or more, 1.33 or more, 1.35 or more, 1.40 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.58 or more, or 1.6. 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 5 or less, 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.5 or less, or 2 or less.

[0078] The above electrolyte composition comprises a binder, a liquid electrolyte, and a crosslinking agent. The first electrolyte composition may comprise a first binder, a first liquid electrolyte, and a first crosslinking agent. The second electrolyte composition may comprise a second binder, a second liquid electrolyte, and a second crosslinking agent.

[0079] The above binder can form a polymer matrix alone or together with the above crosslinking agents.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] The liquid electrolyte content (weight%) of the first electrolyte layer may be in the range of 40 to 70. Preferably, the liquid electrolyte content (weight%) of the first electrolyte layer may be 45 or more, 50 or more, 55 or more, or 58.8 or more. The liquid electrolyte content (weight%) of the first electrolyte layer may be 65 or less, 62.6 or less, 61.6 or less, 61.4 or less, or 60 or less.

[0084] The liquid electrolyte content (weight%) of the second electrolyte layer may be in the range of 50 to 90. The liquid electrolyte content (weight%) of the second electrolyte layer may be 55 or more, 60 or more, 65 or more, 69.1 or more, 70 or more, 71.9 or more, or 72.5 or more. The liquid electrolyte content (weight%) of the second electrolyte layer may be 85 or less, 80 or less, 75.8 or less, or 75 or less.

[0085] 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.

[0086] The first binder is a binder included in the first electrolyte layer, and the second binder is a binder included in the second electrolyte layer.

[0087] The first binder and the second binder may each independently include a fluorine-based binder. The fluorine-based binder may refer to a binder whose constituent unit includes fluorine as part or all. The fluorine-based binder may include a PVDF-based binder.

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

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

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

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

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

[0093] The first unit and second unit content of each of the first binder and the second binder are for the fluorine-based binder 19 It can be measured by F-NMR analysis.

[0094] The weight-average molecular weight of the first binder and the second binder can also be controlled. The weight-average molecular weight (g / mol) of the first binder and the second binder may each independently be in the range of 150,000 to 600,000. Preferably, the weight-average molecular weight (g / mol) of the first binder and the second binder may each independently 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 first binder and the second binder may each independently be 550,000 or less, 500,000 or less, 450,000 or less, 400,000 or less, or 350,000 or less.

[0095] The weight average molecular weight of the first binder and the second binder can be measured by gel permeation chromatography.

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

[0097] 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.

[0098] The above-mentioned non-aqueous solvent may refer to an organic solvent that does not contain water or contains a trace amount of water. The above-mentioned non-aqueous solvent may include carbonate compounds, ether compounds, ester compounds, compounds containing polar functional groups, or mixtures thereof. Preferably, the above-mentioned non-aqueous solvent may include carbonate compounds.

[0099] The above ether-based compound may include dimethoxyethane, diethoxyethane, tetrahydrofuran, or a combination thereof.

[0100] The above ester compound may include N-methyl-2-pyrrolidone (NMP), gamma-butyrolactone (γ-butyrolactone), or a combination thereof.

[0101] The above-mentioned polar functional group-containing compound may include dimethyl sulfoxide, acetonitrile, or a combination thereof.

[0102] The above carbonate-based compound may include a linear carbonate-based compound, a cyclic carbonate-based compound, or a combination thereof. Preferably, the carbonate-based compound may include a linear carbonate-based compound and a cyclic carbonate-based compound.

[0103] In the present invention, the electrolyte layer may contain a linear carbonate compound in a larger volume than a cyclic carbonate compound. Specifically, the electrolyte composition may contain a linear carbonate compound in a larger volume than a cyclic carbonate compound. The first electrolyte layer and the second electrolyte layer may each independently contain a linear carbonate compound in a larger volume than a cyclic carbonate compound. Specifically, the first electrolyte composition and the second electrolyte composition may each independently contain a linear carbonate compound in a larger volume than a cyclic carbonate compound. In this case, the miscibility of the binder with respect to the liquid electrolyte is increased, and an abnormal increase in viscosity of the electrolyte composition can be prevented.

[0104] 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.

[0105] 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.

[0106] The above linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0107] Specifically, the linear carbonate-based compound may include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, or a combination thereof.

[0108] More specifically, the linear carbonate-based compound may include ethylmethyl carbonate.

[0109] The above linear carbonate-based compound may be liquid at room temperature.

[0110] 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.

[0111] Specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, butylene carbonate, or a combination thereof.

[0112] More specifically, the cyclic carbonate compound may include vinylethylene carbonate, vinylene carbonate, ethylene carbonate, propylene carbonate, or a combination thereof.

[0113] 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.

[0114] The above cyclic carbonate-based compound may be solid at room temperature. Specifically, the above cyclic carbonate-based compound may include ethylene carbonate.

[0115] 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.

[0116] The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer and the volume (volume%) of the linear carbonate-based compound in the second electrolyte layer may each independently be within the range of 55 to 95.

[0117] Preferably, the volume (volume%) of the linear carbonate-based compound in the first electrolyte layer and the volume (volume%) of the linear carbonate-based compound in the second electrolyte layer may each independently be 60 or more, 65 or more, or 70 or more. The volume (volume%) of the linear carbonate-based compound in the first electrolyte layer and the volume (volume%) of the linear carbonate-based compound in the second electrolyte layer may each independently be 90 or less, 85 or less, 80 or less, or 75 or less.

[0118] The volume (volume%) of the cyclic carbonate-based compound in the first electrolyte layer and the volume (volume%) of the cyclic carbonate-based compound in the second electrolyte layer may each independently be within a range of 5 to 45. Preferably, the volume (volume%) of the cyclic carbonate-based compound in the first electrolyte layer and the volume (volume%) of the cyclic carbonate-based compound in the second electrolyte layer may each independently 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 first electrolyte layer and the volume (volume%) of the cyclic carbonate-based compound in the second electrolyte layer may each independently be 40 or less, 35 or less, or 30 or less.

[0119] 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.

[0120] The above lithium salt may refer to a material that decomposes into lithium cations and anions upon dissociation.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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. More specifically, the first electrolyte layer and the second electrolyte layer may each independently be thicker than the substrate layer.

[0125] The above crosslinking agent may include multiple types of crosslinking agents. Specifically, the above crosslinking agent includes crosslinking agents having different numbers of crosslinkable functional groups. The above first crosslinking agent may include a 1-1 crosslinking agent and a 1-2 crosslinking agent. The above second crosslinking agent may include a 2-1 crosslinking agent and a 2-2 crosslinking agent. The number of crosslinkable functional groups of the 1-1 crosslinking agent may be greater than the number of crosslinkable functional groups of the 1-2 crosslinking agent. The number of crosslinkable functional groups of the 2-1 crosslinking agent may be greater than the number of crosslinkable functional groups of the 2-2 crosslinking agent.

[0126] In this document, the number of crosslinkable functional groups of a crosslinking agent (or compound) may refer to the number of crosslinkable functional groups per molecule of the crosslinking agent (compound). The said crosslinkable functional groups may be functional groups that act to link binders and / or crosslinking agents in the polymer matrix.

[0127] 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. This is believed to be because the first-1 crosslinking agent and the second-1 crosslinking agent can form a dense crosslinking structure, and the first-2 crosslinking agent and the second-2 crosslinking agent can provide a space for the liquid electrolyte to be impregnated.

[0128] The above crosslinking agent may include a plurality of crosslinking agents, each independently distinguished from one another according to the molecular form of the central moiety. The above crosslinking agent may include monomeric compounds and polymeric compounds.

[0129] The above-mentioned 1-1 crosslinking agent and the above-mentioned 2-1 crosslinking agent may each independently comprise a monomeric compound. The above-mentioned 1-2 crosslinking agent and the above-mentioned 2-2 crosslinking agent may each independently comprise a polymeric compound.

[0130] The above monomeric compound may mean that the remaining moiety, excluding the crosslinking functional group, is of monomer origin. The above polymeric compound may mean that the remaining moiety, excluding the crosslinking functional group, is of polymer origin. When a crosslinking agent with a greater number of functional groups is monomeric and a 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.

[0131] 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.

[0132] For example, the content of the first crosslinking agent in the first electrolyte composition may be greater than the content of the second crosslinking agent in 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.

[0133] The number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent may each be independently 3 or more. In this case, the first-1 crosslinking agent and the second-1 crosslinking agent may form a dense crosslinked structure. Specifically, the number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent may each be independently 6 or less, 5 or less, or 4 or less.

[0134] The above-mentioned crosslinking functional group may include a photoreactive functional group. Specifically, the above-mentioned crosslinking functional group may include a (meth)acryloyl group as a photoreactive functional group. The above-mentioned crosslinking agent may include a polyfunctional (meth)acrylate-based compound. Preferably, from the viewpoint of preventing deterioration of electrochemical properties due to the rate of the crosslinking reaction and the stiffness of the polymer network, the above-mentioned crosslinking functional group may include an acryloyl group as a photoreactive functional group.

[0135] Accordingly, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently 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.

[0136] Specifically, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently include a triacrylate-based compound, a tetraacrylate-based compound, a pentaacrylate-based compound, a hexaacrylate-based compound, or a combination thereof.

[0137] More specifically, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently include a triacrylate-based compound, a tetraacrylate-based compound, or a combination thereof.

[0138] More specifically, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently comprise a triacrylate-based compound.

[0139] The above 1-1 crosslinking agent and the above 2-1 crosslinking agent are each independently 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, It may include ditrimethylolpropane tetra(meth)acrylate, 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.

[0140] Specifically, the 1-1 crosslinking agent and the 2-1 crosslinking agent are each independently 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, and sorbitol It may include pentaacrylate, dipentaerythritol hexaacrylate, ethoxylated dipentaerythritol hexaacrylate, sorbitol hexaacrylate, or a combination thereof.

[0141] More specifically, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently comprise 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.

[0142] More specifically, the first-1 crosslinking agent and the second-1 crosslinking agent may each independently comprise 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.

[0143] The number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may each be independently less than the number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent. If the number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent are each independently 3, the number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may each be independently 2. If the number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent are each independently 4, the number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may each be independently 2 or 3. If the number of crosslinkable functional groups of the 1-1 crosslinking agent and the number of crosslinkable functional groups of the 2-1 crosslinking agent are each independently 5, the number of crosslinkable functional groups of the 1-2 crosslinking agent and the number of crosslinkable functional groups of the 2-2 crosslinking agent may each independently be 2, 3, or 4. If the number of crosslinkable functional groups of the 1-1 crosslinking agent and the number of crosslinkable functional groups of the 2-1 crosslinking agent are each independently 6, the number of crosslinkable functional groups of the 1-2 crosslinking agent and the number of crosslinkable functional groups of the 2-2 crosslinking agent may each independently be 2, 3, 4, or 5.

[0144] Specifically, apart from the number of crosslinkable functional groups of the first-1 crosslinking agent and the number of crosslinkable functional groups of the second-1 crosslinking agent, the number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may each be independently 2. When the number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent are as small as possible, the crosslinking agent with fewer crosslinkable functional groups can more smoothly provide a space for the liquid electrolyte to be impregnated.

[0145] The above crosslinking agent may include a photoreactive functional group, specifically a (meth)acryloyl group, and since the number of crosslinkable functional groups of the first-2 crosslinking agent and the number of crosslinkable functional groups of the second-2 crosslinking agent may be 2, the first-2 crosslinking agent and the second-2 crosslinking agent may each independently include a di(meth)acrylate-based compound.

[0146] In addition, since it is preferable that the photoreactive functional group includes an acryloyl group, the first-2 crosslinking agent and the second-2 crosslinking agent may each independently include a diacrylate-based compound.

[0147] The above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent may each independently 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.

[0148] Specifically, the first-2 crosslinking agent and the second-2 crosslinking agent may each independently include polyethylene glycol diacrylate, poly(ethylene oxide-propylene oxide) diacrylate, polyurethane diacrylate, polycarbonate diacrylate, or a combination thereof.

[0149] More specifically, the first-2 crosslinking agent and the second-2 crosslinking agent may each independently include polyethylene glycol diacrylate, polyurethane diacrylate, or a combination thereof.

[0150] More specifically, the first-2 crosslinking agent and the second-2 crosslinking agent may each independently include polyurethane diacrylate.

[0151] When the first-2 crosslinking agent and the second-2 crosslinking agent each independently include a polymeric compound, the molecular weight of the polymeric compound can also be controlled. The first-2 crosslinking agent and the second-2 crosslinking agent may each independently 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-2 crosslinking agent and the second-2 crosslinking agent may each independently include polyurethane diacrylate with a molecular weight in the range of 1400 g / mol to 2100 g / mol.

[0152] The mixing ratio of the monomeric compound and the polymeric compound can also be appropriately adjusted.

[0153] The ratio (C1-1:C1-2) of the weight of the 1-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the 1-2 crosslinking agent (C1-2) of the first electrolyte layer, and the ratio (C2-1:C2-2) of the weight of the 2-1 crosslinking agent (C2-1) of the second electrolyte layer and the weight of the 2-2 crosslinking agent (C2-2) of the second electrolyte layer, may each independently be within the range of 1:9 to 9:1.

[0154] Preferably, the ratio (C1-1:C1-2) of the weight of the 1-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the 1-2 crosslinking agent (C1-2) of the first electrolyte layer, and the ratio (C2-1:C2-2) of the weight of the 2-1 crosslinking agent (C2-1) of the second electrolyte layer and the weight of the 2-2 crosslinking agent (C2-2) of the second electrolyte layer, may each be independently 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 1-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the 1-2 crosslinking agent (C1-2) of the first electrolyte layer, and the ratio (C2-1:C2-2) of the weight of the 2-1 crosslinking agent (C2-1) of the second electrolyte layer and the weight of the 2-2 crosslinking agent (C2-2) of the second electrolyte layer, may each be independently 8.5:1.5 or less, 8:2 or less, 7.5:2.5 or less, 7:3 or less, 6.5:3.5 or less, 6:4 or less, or 5.5:4.5 or less.

[0155] The weight ratio of the first crosslinking agent and the second crosslinking agent of the above electrolyte layer can be controlled by the content of the first crosslinking agent and the second crosslinking agent of each electrolyte composition.

[0156] The above electrolyte composition may further include an initiator. That is, the above first electrolyte composition may further include a first initiator. The above second electrolyte composition may further include a second initiator.

[0157] When a predetermined stimulus is applied, the initiator can initiate a reaction in which the binder forms a polymer matrix.

[0158] The first initiator and the second initiator may each independently include a thermal polymerization initiator, a photopolymerization initiator, or a combination thereof. Preferably, the first initiator and the second initiator may each independently include a photopolymerization initiator.

[0159] The first initiator and the second initiator may each independently comprise a short-wavelength photopolymerization initiator, a long-wavelength photopolymerization initiator, or a combination thereof. Preferably, the photopolymerization initiator may comprise a long-wavelength photopolymerization initiator.

[0160] 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.

[0161] 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).

[0162] The above substrate layer may include a polyolefin-based film. Specifically, the above substrate layer may include a porous polyolefin-based film.

[0163] Here, a polyolefin-based porous film refers to a porous film containing a polyolefin-based resin as a main component.

[0164] 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.

[0165] 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.

[0166] 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.

[0167] 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.

[0168] 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. The above first electrolyte layer may include a cured product of the above first electrolyte composition. The above second electrolyte layer may include a cured product of the above second electrolyte composition.

[0169] The above curing method may include, for example, thermal curing, photocuring, and thermal-photo dual curing. Preferably, the curing method may be photocuring.

[0170] 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.

[0171] The above-mentioned inorganic particles may exist in various forms in the battery separator.

[0172] The inorganic particles may be located in the electrolyte layer. That is, the inorganic particles may be located in the first electrolyte layer and the second electrolyte layer. Specifically, the first electrolyte composition and the second 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. When the second electrolyte composition is cured, the inorganic particles may be located in the second electrolyte layer. At this time, the first electrolyte layer and the second 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, and between the second electrolyte layer and the substrate layer.

[0173] The above inorganic particles may exist as a separate layer from the substrate layer, the first electrolyte layer, and the second electrolyte layer in the battery separator.

[0174] The battery separator may further include an inorganic layer located between the substrate layer and the electrolyte layer. Specifically, the battery 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. The inorganic particles may be located in the first inorganic layer and the second inorganic layer. In this case, the first electrolyte layer, the second electrolyte layer, the first electrolyte composition, or the second electrolyte composition may not include the inorganic particles.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] 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 x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3)를 포함할 수 있다.

[0179] The first inorganic particle mentioned above may be a polygonal inorganic particle.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] 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.

[0199] The green density of the first inorganic particle may be greater than the green density of the second inorganic particle.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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.

[0204] 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.

[0205] 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.

[0206] 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.

[0207] 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.

[0208] Additionally, the electrolyte composition may be impregnated into the pores of the substrate layer. That is, the first electrolyte composition and the second electrolyte composition may be impregnated into the pores of the substrate layer. Accordingly, at least a portion of the first electrolyte layer containing a cured product of the first electrolyte composition, and / or at least a portion of the second electrolyte layer containing a cured product of the second electrolyte composition may be impregnated into the pores of the substrate layer.

[0209] A UV curing method may be applied in such a way that the first electrolyte layer and the second electrolyte layer are formed on the 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 being dispersed, and the process of the liquid electrolyte being impregnated may proceed in the same stage.

[0210] The above UV curing method may include the following steps. The number of each step does not indicate the order of the steps:

[0211] (1) Prepare the first electrolyte composition and the second electrolyte composition;

[0212] (2) Applying the first electrolyte composition to one surface of the substrate layer;

[0213] (3) Applying the second electrolyte composition to the other surface of the above substrate layer; and

[0214] (4) Irradiating UV light onto the first electrolyte composition and the second electrolyte composition.

[0215] 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.

[0216] Conditions such as the application method and thickness of the first electrolyte composition and the second electrolyte composition are not particularly limited.

[0217] The conditions of UV irradiation applied to the first electrolyte composition and the second electrolyte composition are not particularly limited.

[0218] Another embodiment of the present invention is a battery.

[0219] 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).

[0220] 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.

[0221] 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.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] 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.

[0226] 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.

[0227] The battery separator of the present invention may be more suitable when the battery is a lithium metal battery. That is, the negative electrode may include lithium metal. Specifically, the negative electrode may include copper as a negative electrode current collector and lithium metal as a negative electrode active material. In particular, the negative electrode may include lithium metal as a main component (e.g., a content of 90 weight% or more) as the negative electrode active material.

[0228] When the above battery is a lithium metal battery, the first electrolyte layer may be located between the substrate layer and the negative electrode. Specifically, the first electrolyte layer may be located adjacent to the negative electrode. The second electrolyte layer may be located between the substrate layer and the positive electrode. Specifically, the second electrolyte layer may be located adjacent to the positive electrode.

[0229] Accordingly, problems caused by the expansion of the negative electrode during the charging and discharging process of the above lithium metal battery can be reduced, and the performance of the battery can be improved.

[0230] The present invention is described in more detail below through examples and comparative examples. However, the present invention is not limited to the examples.

[0231] [manufacturing]

[0232] Example 1. Battery separator

[0233] A battery separator was manufactured according to the following process.

[0234] (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 (polygonal Li) of Ganfeng Lithium. 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)

[0235] (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%).

[0236] (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%).

[0237] (4) Prepare a solution by adding 5 g of binder, 8 g of monomeric crosslinking agent, and 2 g of polymeric 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 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 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.

[0238] (5) Prepare a solution by adding 1.67 g of binder, 2.67 g of monomeric crosslinking agent, and 0.67 g of polymeric crosslinking agent to 95 g of liquid electrolyte, stir the solution with a homogenizer, and then add 0.07 g of photopolymerization initiator to the solution to prepare a second electrolyte composition.

[0239] (6) Apply the first electrolyte composition to the upper surface of the structure on which the above-mentioned inorganic layer is located, apply the second electrolyte composition to the lower surface, and cure with UV irradiation to produce a battery separator with a total thickness of 50 μm.

[0240] Example 2. Battery separator

[0241] A battery separator was prepared by repeating the same process as in Example 1, except that 6 g of monomeric crosslinking agent and 4 g of polymeric crosslinking agent were added in (4) above to prepare the first electrolyte composition.

[0242] Example 3. Battery separator

[0243] A battery separator was prepared by repeating the same process as in Example 1, except that a second electrolyte composition was prepared by adding 2 g of monomeric crosslinking agent and 1.34 g of polymeric crosslinking agent in (5) above.

[0244] Example 4. Battery separator

[0245] A battery separator was prepared by repeating the same process as in Example 1, except that in (4) a first electrolyte composition was prepared by adding 5 g of binder, 12 g of monomeric crosslinking agent, and 3 g of polymeric crosslinking agent to 80 g of liquid electrolyte, and in (5) a second electrolyte composition was prepared by adding 1.67 g of binder, 4.66 g of monomeric crosslinking agent, and 1.17 g of polymeric crosslinking agent to 92.5 g of liquid electrolyte.

[0246] Comparative Example 1. Battery separator

[0247] A battery separator was manufactured by repeating the same process as in Example 1, except that the process of (5) above is not carried out and the first electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0248] Comparative Example 2. Battery Separator

[0249] A battery separator was manufactured by repeating the same process as in Example 2, except that the process of (5) above is not carried out and the first electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0250] Comparative Example 3. Battery Separator

[0251] A battery separator was manufactured by repeating the same process as in Example 1, except that the process of (4) above is not carried out and the second electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0252] Comparative Example 4. Battery Separator

[0253] A battery separator was manufactured by repeating the same process as in Example 3, except that the process of (4) above is not carried out and the second electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0254] Comparative Example 5. Battery Separator

[0255] A battery separator was manufactured by repeating the same process as in Example 4, except that the process of (5) above is not carried out and the first electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0256] Comparative Example 6. Battery Separator

[0257] A battery separator was manufactured by repeating the same process as in Example 4, except that the process of (4) above is not carried out and the second electrolyte composition is applied to the upper and lower surfaces of the structure where the inorganic layer is located in (6) above.

[0258] [evaluation]

[0259] Experimental Example 1. Shape of inorganic particles

[0260] 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.

[0261] (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 ℃).

[0262] (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).

[0263] (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).

[0264] (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).

[0265] (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.

[0266] 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.

[0267] 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.

[0268] 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.

[0269] (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.

[0270] 1) Needle-shaped or plate-shaped particles: The average longitudinal length is determined by the average of the number of inorganic particles with the maximum length of each inorganic particle. The average transverse length is determined by the average of the number of inorganic particles with the length in the direction perpendicular to the maximum length of each inorganic particle.

[0271] 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.

[0272] Experimental Example 2. Green density of inorganic particles

[0273] The green density of inorganic particles was measured according to the following process.

[0274] (1) Pre-treat inorganic particles by vacuum drying (80 ℃, 6 hours) followed by aging (25 ℃, 7 days).

[0275] (2) Place 1 g of pretreated inorganic particles into a cylindrical mold with a diameter of 16 mm.

[0276] (3) Next, in the above cylindrical mold, 1 ton / cm under the following conditions 2 To produce a specimen in the form of a compacted pellet (green pellet) by applying pressure.

[0277] Pressure application equipment: Carver hydraulic press 4386,

[0278] Applying load holding time: 30 seconds

[0279] Compression count: 1 time

[0280] (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.

[0281] (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.

[0282] Experimental Example 3. Electrical Resistance and Ionic Conductivity

[0283] The resistance and ion conductivity of the battery separator were evaluated according to the following process.

[0284] (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)

[0285] (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.

[0286] Experimental Example 4. Gel content of electrolyte composition

[0287] The gel content of the electrolyte composition was measured by the following process.

[0288] (1) Measure the content (A) of the electrolyte composition sample.

[0289] (2) Dry the sample in a convection oven at 200°C for 24 hours.

[0290] (3) Measure the weight (B) of the dried object.

[0291] (4) The process of converting the weight ratio (B / A) of the electrolyte composition sample before (A) and after (B) drying into % is performed 3 times, and the average of the number of times is determined as the gel content.

[0292] Experimental Example 5. Battery Performance

[0293] The discharge capacity and capacity retention rate of the battery manufactured using the battery separator were measured through the following process.

[0294] (1) Prepare a slurry in which a mixture of 94 wt% LiNiCoMnO2 (Ni:Co:Mn=8:1:1) as a positive active material, 3 wt% conductive carbon black (Super P; IMERYS Graphite & Carbon) as a conductive material, and 3 wt% polyvinylidene fluoride with a weight-average molecular weight of about 800,000 as a binder is uniformly dispersed in NMP (N-methyl-2-pyrrolidone).

[0295] (2) The above slurry is applied to one side of a 20 μm thick aluminum current collector at a pressure of 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.

[0296] (3) The above positive plate is 1.54 cm 2 Stamping into (14 pi) size.

[0297] (4) Produce a cathode plate with a total thickness of 100 μm by rolling lithium metal (negative active material layer) onto a copper plate with a thickness of 10 μm.

[0298] (5) The above cathode plate is 1.76 cm 2 Stamping to a size of (15 pi).

[0299] (6) 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.

[0300] (7) Complete the battery by placing 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.

[0301] Prepare the electrochemical analyzer (Toyo, Toscat-3100).

[0302] (8) Charge the battery using the CC-CV method under conditions of 0.2 C, 4.3 V, cut-off 0.05 C, and discharge the battery under conditions of 0.5 C, 3.0 V, cut-off 0.05 C.

[0303] (9) Measure the initial (1 cycle) charge and discharge capacity.

[0304] (10) Measure the charge and discharge capacity after repeating 50 cycles.

[0305] [Results and Discussion]

[0306] Table 1 below shows the test results of the examples and comparative examples.

[0307] Example Comparative Example 1 2341 23456 Solid content (1) Weight % 38.6 37.4 38.4 41.2 38.6 37.4 27.5 24.2 41.2 30.9 Solid content (2) Weight % 27.5 28.1 24.2 30.9 38.6 37.4 27.5 24.2 41.2 30.9 Resistance Ohm 1.2 41.0 9 1.0 11.4 21.6 91.5 80.8 90.8 42.7 71.01 Ionic conductivity mS / cm 2.8 13.1 93.4 52.4 52.0 62.2 3.9 14.1 41.2 63.45 Charge / discharge cycle test 1st Cycle Charge Capacity mAh / g 41.9 42.5 42.1 40.7 38.8 39.4 40.1 40.6 31.7 38.6 Discharge Capacity mAh / g 42.9 42.8 42.9 42.6 40.5 39.9 40.9 41.0 31.9 40.1 10 Cycle Charge Capacity mAh / g 41.5 40.4 39.6 38.9 34.1 33.7 29.1 27.5 20.2 28.9 Discharge Capacity mAh / g 42.4 41.8 40.9 40.9 39.5 34.3 37.8 28.7 21.1 29.7 Discharge Capacity Retention Rate % 98.1 95.1 94.1 95.6 87.9 85.9 72.6 69.9 66.2 74.0 Solid Content (1): First Electrolyte Solid content of the composition Solid content (2): Solid content of the second electrolyte composition

Claims

1. Record layer; A first electrolyte layer located on one surface of the above-mentioned substrate layer and comprising a first electrolyte composition; A second electrolyte layer located on the other side of the above substrate layer and comprising a second electrolyte composition; and Inorganic particles; Includes, A battery separator in which the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

2. In Paragraph 1, A battery separator in which 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 is 1.05 or higher.

3. In Paragraph 1, The above first electrolyte composition comprises a first binder, a first liquid electrolyte, and a first crosslinking agent, and The second electrolyte composition comprises a second binder, a second liquid electrolyte, and a second crosslinking agent, and A battery separator in which the first liquid electrolyte content (weight%) of the first electrolyte composition is less than the second liquid electrolyte content (weight%) of the second electrolyte composition.

4. In Paragraph 3, The first binder and the second binder each independently comprise a first unit of vinylidene fluoride and a second unit of a fluorine-containing alkyl vinyl compound, forming a battery separator.

5. In Paragraph 4, The weight average molecular weight (g / mol) of the first binder and the second binder is independently within the range of 150,000 to 600,000, and A battery separator in which the second unit content (weight%) of the first binder and the second binder is independently within the range of 10 to 25.

6. In Paragraph 3, The first liquid electrolyte and the second liquid electrolyte each independently comprise a battery separator comprising a non-aqueous solvent, a lithium salt, and an additive.

7. In Paragraph 3, The above-mentioned first crosslinking agent comprises a first-1 crosslinking agent and a first-2 crosslinking agent, and The above second crosslinking agent comprises a 2-1 crosslinking agent and a 2-2 crosslinking agent, and The number of crosslinkable functional groups of the above-mentioned 1-1 crosslinking agent is greater than the number of crosslinkable functional groups of the above-mentioned 1-2 crosslinking agent, and A battery separator having more crosslinkable functional groups than the number of crosslinkable functional groups of the above 2-1 crosslinking agent.

8. In Paragraph 7, The above-mentioned 1-1 crosslinking agent and the above-mentioned 2-1 crosslinking agent each independently comprise a monomeric compound in a battery separator.

9. In Paragraph 7, A battery separator in which the number of crosslinkable functional groups of the above 1-1 crosslinking agent and the number of crosslinkable functional groups of the above 2-1 crosslinking agent are each independently 3 or more.

10. In Paragraph 7, A battery separator comprising, respectively, a tri(meth)acrylate compound, a tetra(meth)acrylate compound, a penta(meth)acrylate compound, a hexa(meth)acrylate compound, or a combination thereof.

11. In Paragraph 7, The above 1-1 crosslinking agent and the above 2-1 crosslinking agent are each independently 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, A battery separator comprising ditrimethylolpropane tetra(meth)acrylate, 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.

12. In Paragraph 7, The above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent each independently comprise a polymeric compound in a battery separator.

13. In Paragraph 7, A battery separator having 2 crosslinkable functional groups of the first-2 crosslinking agent and 2 crosslinkable functional groups of the second-2 crosslinking agent.

14. In Paragraph 7, The above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent each independently comprise a battery separator comprising a di(meth)acrylate-based compound.

15. In Paragraph 7, A battery separator comprising the above-mentioned first-2 crosslinking agent and the above-mentioned second-2 crosslinking agent, each independently 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.

16. In Paragraph 7, A battery separator in which the ratio (C1-1:C1-2) of the weight of the 1-1 crosslinking agent (C1-1) of the first electrolyte layer and the weight of the 1-2 crosslinking agent (C1-2) of the first electrolyte layer, and the ratio (C2-1:C2-2) of the weight of the 2-1 crosslinking agent (C2-1) of the second electrolyte layer and the weight of the 2-2 crosslinking agent (C2-2) of the second electrolyte layer are each independently within the range of 1:9 to 9:

1.

17. In Paragraph 6, A battery separator in which the first electrolyte layer and the second electrolyte layer each independently contain a linear carbonate-based compound in a larger volume than a cyclic carbonate-based compound.

18. In Paragraph 17, 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.

19. In Paragraph 17, The above linear carbonate-based compound is a battery separator that is liquid at room temperature.

20. In Paragraph 17, 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.

21. In Paragraph 17, The above-mentioned cyclic carbonate-based compound is a battery separator that is solid at room temperature.

22. In Paragraph 17, A battery separator in which the volume (volume%) of the linear carbonate-based compound of the first electrolyte layer and the volume (volume%) of the linear carbonate-based compound of the second electrolyte layer are each independently within the range of 55 to 95.

23. In Paragraph 1, The above substrate layer is a battery separator comprising a polyolefin-based film.

24. In Paragraph 1, The first electrolyte layer comprises a cured product of the first electrolyte composition, and The above second electrolyte layer is a battery separator comprising a cured product of the above second electrolyte composition.

25. In Paragraph 1, The above inorganic particles are battery separators located in the first electrolyte layer and the second electrolyte layer.

26. In Paragraph 1, A first inorganic layer located between the above substrate layer and the above first electrolyte layer; and It further includes a second inorganic layer located between the above substrate layer and the above second electrolyte layer, and The above inorganic particles are battery separators located in the first inorganic layer and the second inorganic layer.

27. In Paragraph 1, The above-mentioned inorganic particles comprise a first inorganic particle capable of lithium ion transfer and a second inorganic particle capable of flame retardancy, forming a battery separator.

28. In Paragraph 27, 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.

29. In Paragraph 27, 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.

30. In Paragraph 27, 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.

31. In Paragraph 27, The above second inorganic particle is a battery separator that is a needle-shaped or plate-shaped inorganic particle.

32. In Paragraph 27, 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.

33. In Paragraph 27, 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.

34. A positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, and The above separator comprises: a substrate layer; a first electrolyte layer located on one side of the substrate layer and comprising a first electrolyte composition; a second electrolyte layer located on the other side of the substrate layer and comprising a second electrolyte composition; and inorganic particles. A battery in which the solid content (weight%) of the first electrolyte composition is greater than the solid content (weight%) of the second electrolyte composition.

35. In Paragraph 34, The above cathode includes lithium metal, and The first electrolyte layer is located adjacent to the cathode, and The above second electrolyte layer is a battery located adjacent to the above positive electrode.