Separator for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The present disclosure relates to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the same. The separator includes a porous substrate, a coating layer on at least one surface of the porous substrate, and an adhesive layer on one surface of the coating layer. The coating layer includes a crosslinking product of a binder, a crosslinking agent and a carboxyalkyl cellulose or a salt thereof, and a filler. The binder includes a (meth) acrylic binder including a first structural unit derived from (meth) acrylamide and a second structural unit derived from (meth) acrylamide sulfonic acid or a salt thereof. The cross-linking agent includes an aziridine-based cross-linking agent, and the adhesive layer includes a (meth) acrylic adhesive.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0125491, filed on September 13, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to a separator for a rechargeable lithium battery and a rechargeable lithium battery including the separator. Background Technology

[0003] With the increasing prevalence of battery-powered electronic devices (such as mobile phones, laptops, and electric vehicles), the demand for rechargeable batteries with high energy density and high capacity is growing. Therefore, improving the performance of rechargeable lithium batteries can be beneficial.

[0004] A rechargeable lithium battery typically includes a positive electrode and a negative electrode, as well as an electrolyte. The positive and negative electrodes contain active materials capable of inserting and deintercalating lithium ions, and the rechargeable lithium battery generates electrical energy through redox reactions during the insertion and deintercalation of lithium ions into and from the positive and negative electrodes.

[0005] Rechargeable lithium-ion batteries may include a separator between the positive and negative electrodes. The separator may be immersed in an electrolyte. To improve battery safety, it may be desirable for the separator to retain its original shape and not shrink due to heat in the electrolyte. Summary of the Invention

[0006] This disclosure describes a separator for a rechargeable lithium battery that provides the battery with desired or improved safety when exposed to heat.

[0007] This disclosure describes a rechargeable lithium battery including the separator.

[0008] One aspect of this disclosure includes a separator for rechargeable lithium batteries.

[0009] A separator for a rechargeable lithium-ion battery includes a porous substrate, a coating layer on at least one surface of the porous substrate, and an adhesive layer on one surface of the coating layer. The coating layer includes a binder, a crosslinking agent, and a crosslinking product of carboxyalkyl cellulose or its salts, as well as a filler. The binder includes a (meth)acrylic binder comprising a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or its salts. The crosslinking agent includes an aziridine crosslinking agent, and the adhesive layer includes a (meth)acrylic adhesive.

[0010] Another aspect of this disclosure includes a rechargeable lithium battery.

[0011] A rechargeable lithium battery includes a positive electrode, a negative electrode, and a separator for the rechargeable lithium battery, with the separator located between the positive and negative electrodes.

[0012] According to one aspect, a separator for rechargeable lithium batteries can enable batteries with desired or improved safety when exposed to heat, thereby improving battery reliability. Attached Figure Description

[0013] The above and other objects, features, and advantages of this disclosure will become more apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0014] Figure 1 This is a cross-sectional view of a separator for a rechargeable lithium battery according to an example embodiment;

[0015] Figure 2 This is a conceptual diagram of a stacked electrode assembly according to an example embodiment;

[0016] Figures 3 to 6 This is a schematic cross-sectional view of a rechargeable lithium battery according to an example embodiment;

[0017] Figure 7 This is a conceptual diagram of the jelly roll used to measure dry bending strength.

[0018] Figure 8 This is a conceptual diagram of the three-point bending test for measuring dry bending strength; and

[0019] Figure 9 This is a conceptual diagram of a hot tip test. Detailed Implementation

[0020] Hereinafter, exemplary embodiments of the present disclosure are described in detail. However, the embodiments are presented by way of example, and the present disclosure is not limited thereto, and is limited only by the scope of the appended claims.

[0021] Unless otherwise stated herein, when a component such as a layer, membrane, region, plate, etc. is described as being disposed "on" another component, it includes not only the case where the component is "directly on" another component, but also the case where there are one or more other components between them.

[0022] Unless otherwise stated herein, the singular may also include the plural. Furthermore, unless otherwise stated, the term "A or B" may mean "including A, including B, or including both A and B".

[0023] In this disclosure, “combination of them” can mean a mixture, stack, complex, copolymer, alloy, blend or reaction product of the components.

[0024] Unless otherwise defined herein, “particle size D100” can refer to the size of particles that constitute 100% of the cumulative volume in a particle size distribution. Particle size distribution can be measured by methods known to those skilled in the art. For example, particle size distribution can be measured using a particle size analyzer, transmission electron microscopy (TEM) images, or scanning electron microscopy (SEM) images. Alternatively, particle size distribution can be obtained by measuring particle size using a measuring device that utilizes dynamic light scattering, performing data analysis to count the number of particles in each particle size range, and then calculating the particle size D100 from this data. Optionally, particle size distribution can be measured using laser diffraction. When measuring particle size distribution by laser diffraction, for example, the particle size D100 can be calculated based on 100% of the particle size distribution in the measuring device by dispersing the particles to be measured in a dispersion medium, introducing the dispersion medium into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT3000), and irradiating the dispersion medium with ultrasound at an output of approximately 60 W at approximately 28 kHz.

[0025] Unless otherwise defined herein, “particle size D50” may refer to the size of particles that constitute 50% of the cumulative volume in the particle size distribution. The particle size distribution can be obtained from methods describing particle size D100.

[0026] According to one example embodiment, the size can be the diameter.

[0027] In this disclosure, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0028] In the following text, unless otherwise defined, “substitution” means that hydrogen in a compound is replaced by a substituent, such as or including C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 alkylaryl, C1 to C30 alkoxy, C1 to C30 heteroalkyl, C3 to C30 heteroalkylaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C30 cycloalkynyl, C2 to C30 heterocycloalkyl, halogen (F, Cl, Br or I), hydroxyl (-OH), nitro (-NO2), cyano (-CN), amino (-NRR') (here, R and R' are both independently hydrogen or C1 to C6 alkyl), sulfobetaine (-RR'N) + (CH2) n SO3 - (where n is a natural number from 1 to 10) (here, R and R′ are both independently C1 to C20 alkyl groups), carboxybenzene group (-RR'N) + (CH2) n COO -(where n is a natural number from 1 to 10) (where R and R' are both independently C1 to C20 alkyl), azide (-N3), amidine (-C(=NH)NH2)), hydrazine (-NHNH2), hydrazone (=N(NH2)), carbamoyl (-C(O)NH2), thiol (-SH), acyl (-C(=O)R, where R represents hydrogen, C1 to C6 alkyl, C1 to C6 alkoxy or C6 to C12 aryl), carboxyl (-COOH) or a salt thereof (-C(=O)OM, where M represents an organic or inorganic cation), sulfonic acid (-SO3H) or a salt thereof (-SO3M, where M represents an organic or inorganic cation), phosphate (-PO3H2) or a salt thereof (-PO3MH or -PO3M2, where M represents an organic or inorganic cation) and at least one combination thereof.

[0029] In the following text, C1 to C3 alkyl groups may be or include methyl, ethyl, or propyl. C1 to C10 alkylene groups may be, for example, C1 to C6 alkylene groups, C1 to C5 alkylene groups, or C1 to C3 alkylene groups, and may be, for example, methylene, ethylene, or propylene. C3 to C20 cycloalkylene groups may be, for example, C3 to C10 cycloalkylene groups or C5 to C10 cycloalkylene groups (e.g., cyclohexylene). C6 to C20 arylene groups may be, for example, C6 to C10 arylene groups (e.g., phenylene). C3 to C20 heterocyclic groups may be, for example, C3 to C10 heterocyclic groups (e.g., pyridyl).

[0030] In the following text, “heterogeneous” means including one or more heteroatoms (such as being or including at least one of N, O, S, Si and P).

[0031] Additionally, in chemical formulas, the symbol * indicates a portion connected to the same or different atoms, groups, or structural units. Unless otherwise stated in the chemical formulas described herein, it can be assumed that hydrogen bonds are present in the structure of the chemical formula.

[0032] In the following text, "alkali metals" refers to elements belonging to Group 1 of the periodic table (such as lithium, sodium, potassium, rubidium, cesium, or francium) that can exist in either a cation or a neutral state.

[0033] In this disclosure, when describing a range of values, “X to Y” means “X or greater and Y or less (greater than or equal to X and less than or equal to Y)”.

[0034] When the terms “about” or “basic” are used in conjunction with numerical values ​​in this specification, it means that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0035] A separator for a rechargeable lithium-ion battery according to an example embodiment includes a porous substrate, a coating layer on at least one surface of the porous substrate, and an adhesive layer on one surface of the coating layer. The coating layer includes a binder, a crosslinking agent, and a crosslinking product of carboxyalkyl cellulose or a salt thereof, as well as a filler. The binder includes a (meth)acrylic binder comprising a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or a salt thereof. The crosslinking agent includes an aziridine crosslinking agent, and the adhesive layer includes a (meth)acrylic adhesive.

[0036] According to one example embodiment, the coating layer may be formed from a composition for the coating layer, the composition for the coating layer including (meth)acrylic binders, aziridine crosslinking agents, carboxyalkyl cellulose or salts thereof, and fillers.

[0037] According to one example embodiment, the crosslinking product may be or include a thermally crosslinked product.

[0038] The separator may include a coating layer and an adhesive layer located (e.g., sequentially located) on a porous substrate, thereby providing desired or improved safety for batteries exposed to heat. In this regard, the separator can provide desired or improved safety for batteries exposed to heat by offering low dry shrinkage, low shrinkage in the electrolyte, high bonding strength between the porous substrate and the coating layer, and high dry flexural strength of the electrode plates. The excellent safety of the aforementioned batteries under heat exposure can be confirmed by shrinkage in the electrolyte and hot tip (HOT-TIP) evaluation tests.

[0039] According to one example embodiment, the dry shrinkage rate of the diaphragm may be about 5% or less in each of the longitudinal (MD) and transverse (TD) directions, and the shrinkage rate in the electrolyte may be about 15% or less in each of the MD and TD directions (e.g., 10% or less or 5% or less). Here, "MD" and "TD" are the same directions as the MD and TD of the porous substrate.

[0040] According to one example embodiment, the diaphragm may have a coating strength of about 1.8 N or greater with the porous substrate.

[0041] According to one example embodiment, the diaphragm may have a dry bending strength of about 95 N or greater relative to the electrode plate. This dry bending strength can be advantageous for the stacked electrode assembly described below.

[0042] Separators with only a coating layer and no adhesive layer on a porous substrate may struggle to provide the desired or improved safety for batteries exposed to heat. Similarly, separators with adhesive binders in the coating layer but without the coating and adhesive layers being formed or sequentially formed on the porous substrate may also struggle to provide the desired or improved safety for batteries exposed to heat.

[0043] A membrane having a coating formed from such a composition for coating may be difficult to provide the desired or improved safety for a battery exposed to heat, the composition for coating including (meth)acrylic binders but excluding aziridine crosslinkers as crosslinkers or including crosslinkers other than aziridine crosslinkers.

[0044] According to one example embodiment, in the composition used for the coating layer, the content of the aziridine crosslinking agent may be about 95 wt% or more of the total crosslinking agent (e.g., 98 wt% to 100 wt%, or 100 wt%).

[0045] A diaphragm having a coating formed from such a composition for coating may not reach the range of dry shrinkage and shrinkage in the electrolyte, the composition for coating comprising an aziridine crosslinking agent and filler, but excluding (meth)acrylic binders or containing binders other than (meth)acrylic binders. According to an example embodiment, in the composition for coating, the content of (meth)acrylic binder may be about 95 wt% or more of the total binder (e.g., 98 wt% to 100 wt%, or 100 wt%).

[0046] Membranes with coatings formed from compositions that do not include carboxyl cellulose or its salts may be difficult to provide the desired or improved safety for batteries exposed to heat.

[0047] Coating layer

[0048] The coating is a heat-resistant layer, and the adhesive includes a (meth)acrylic adhesive, which includes a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or a salt thereof.

[0049] According to one example embodiment, the total content of the first and second structural units may be about 95 mol% or more (e.g., 95 mol% to 100 mol%, or 100 mol%) relative to 100 mol% of (meth)acrylic adhesive.

[0050] (Meth)acrylic adhesives may also include a third structural unit derived from (meth)acrylic acid or (meth)acrylate.

[0051] According to one example embodiment, the total content of the first structural unit, the second structural unit, and the third structural unit may be 95 mol% or greater (e.g., 95 mol% to 100 mol%, or 100 mol%) relative to 100 mol% of the (meth)acrylic adhesive.

[0052] (Meth)acrylic binders are or include water-based heat-resistant binders that can fix fillers to porous substrates and provide adhesion, allowing the coating to adhere to the porous substrate and electrodes, and can help improve the heat resistance, permeability and oxidation resistance of the diaphragm.

[0053] The first structural unit derived from (meth)acrylamide has an amide functional group (-(C=O)-NH2) in the structural unit. The (-(C=O)-NH2) functional group can improve the adhesion between the porous substrate and the electrode, and can also more firmly fix inorganic particles in the coating layer by forming hydrogen bonds with the -OH functional group of the filler, thereby enhancing the heat resistance of the membrane.

[0054] The second structural unit derived from (meth)acrylamide sulfonic acid or its salt can enhance the heat resistance of the membrane by reducing the mobility of binders containing bulk functional groups.

[0055] The third structural unit derived from (meth)acrylic acid or (meth)acrylate can immobilize the filler on the porous substrate and also provide adhesion, allowing the coating to adhere to the porous substrate and the electrode, and can help improve the heat resistance and permeability of the membrane. Furthermore, the structural unit derived from (meth)acrylic acid or (meth)acrylate can include a carboxyl functional group (-C(=O)O-) within the structural unit, thus helping to improve the dispersibility of the composition used for the coating.

[0056] The content of the first structural unit relative to 100 mol% of (meth)acrylic adhesive can be in the range of about 55 mol% to about 95 mol% (e.g., 70 mol% to 95 mol%, 75 mol% to 95 mol%, 80 mol% to 95 mol%, or 80 mol% to 90 mol%).

[0057] The total content of the second and third structural units relative to 100 mol% of (meth)acrylic adhesives can be in the range of about 5 mol% to 45 mol% (e.g., 5 mol% to 30 mol%, 5 mol% to 25 mol%, 5 mol% to 20 mol%, or 10 mol% to 20 mol%).

[0058] The content of the second structural unit relative to 100 mol% of (meth)acrylic adhesive can be in the range of about 0.1 mol% to about 45 mol% (e.g., 5 mol% to 45 mol%, 0.1 mol% to 30 mol%, 0.1 mol% to 20 mol%, 0.1 mol% to 10 mol%, or 1 mol% to 10 mol%).

[0059] The content of the third structural unit relative to 100 mol% of (meth)acrylic adhesive can be in the range of about 0 mol% to about 30 mol% (e.g., 1 mol% to 30 mol%, 1 mol% to 20 mol%, 1 mol% to 10 mol%, 5 mol% to 15 mol%, or 5 mol% to 20 mol%).

[0060] When the content of each structural unit is within the above range, the heat resistance and adhesion of the diaphragm can be further improved.

[0061] The first structural unit derived from (meth)acrylamide can be represented by the following chemical formula 1.

[0062] Chemical Formula 1:

[0063]

[0064] In chemical formula 1,

[0065] R 1 and R 2 Each is independently hydrogen or includes methyl.

[0066] The second structural unit derived from (meth)acrylamide sulfonic acid or its salt may be or include structural units derived from (meth)acrylamide sulfonic acid or (meth)acrylamide sulfonate, wherein (meth)acrylamide sulfonate may be or include a conjugate base of (meth)acrylamide sulfonic acid, (meth)acrylamide sulfonate, or derivatives thereof. The structural unit derived from (meth)acrylamide sulfonic acid or (meth)acrylamide sulfonate may be represented by any one of, for example, the following chemical formulas 2, 3, 4, and combinations thereof.

[0067] Chemical formula 2:

[0068]

[0069] Chemical formula 3:

[0070]

[0071] Chemical formula 4:

[0072]

[0073] In chemical formulas 2 to 4,

[0074] R 10 R 11 R 12 R 13 R 14 and R 15 Each is independently hydrogen or includes methyl.

[0075] L 1 L 2 and L 3 Each of these groups is independently or comprises a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C3 to C20 cycloalkylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C3 to C20 heterocyclic group.

[0076] a, b, and c are each an independent integer in the range of 0 to 2, and M is or includes an alkali metal, which may be or include at least one of lithium, sodium, potassium, rubidium, or cesium.

[0077] For example, in chemical formulas 2 to 4, L 1 L 2 and L 3 Each of them may be independently or include substituted or unsubstituted C1 to C10 alkylene groups, and a, b and c may each be equal to 1.

[0078] The structural units derived from (meth)acrylamide sulfonic acid or its salts may include structural units represented by chemical formula 2, chemical formula 3, or chemical formula 4, or two or more of these. In one example, the structural unit represented by chemical formula 2 may be included, and in another example, both structural units represented by chemical formula 2 and chemical formula 3 may be included.

[0079] When both structural units represented by chemical formula 2 and structural units represented by chemical formula 3 are included, the structural units represented by chemical formula 2 and structural units represented by chemical formula 3 may be included in a molar ratio in the range of about 10:1 to about 1:2 (e.g., 5:1 to 1:1, e.g., 3:1 to 1:1).

[0080] The sulfonate group in the structural unit derived from (meth)acrylamide sulfonic acid or its salt may be or include, for example, a functional group derived from at least one of vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, anisole sulfonic acid, acrylamide alkane sulfonic acid, alkyl sulfonyl (meth)acrylate, or their salts. Here, the alkane may be or include at least one of C1 to C20 alkanes, C1 to C10 alkanes, or C1 to C6 alkanes, and the alkyl group may be C1 to C20 alkyl, C1 to C10 alkyl, or C1 to C6 alkyl. The salt is a salt consisting of or including the aforementioned sulfonic acid and suitable ions. The ions may be or include, for example, alkali metal ions, and in this case, the salt may be or include an alkali metal sulfonate salt.

[0081] Acrylamide alkyl sulfonic acids can be or include, for example, 2-acrylamide-2-methylpropane sulfonic acid.

[0082] The third structural unit derived from (meth)acrylic acid or (meth)acrylate can be represented by any one of the following chemical formulas 5, 6, 7 and combinations thereof.

[0083] Chemical formula 5:

[0084]

[0085] Chemical formula 6:

[0086]

[0087] Chemical Formula 7:

[0088]

[0089] In chemical formulas 5 to 7

[0090] R 3 R 4 R 6 R 7 R 8 and R 9 Each is independently hydrogen or includes methyl.

[0091] R 5 It is or includes substituted or unsubstituted C1 to C20 alkyl groups, and

[0092] M is or includes alkali metals.

[0093] The structural unit derived from (meth)acrylates can be derived from at least one of alkyl (meth)acrylates, perfluoroalkyl (meth)acrylates, and (meth)acrylates having a functional group in the side chain (e.g., derived from (meth)acrylates). Furthermore, the number of carbon atoms in the alkyl or perfluoroalkyl group bonded to the non-carbonyl oxygen atom of the alkyl (meth)acrylate or perfluoroalkyl (meth)acrylate can, for example, range from 1 to 20 (or, for example, 1 to 10, or, for example, 1 to 5).

[0094] Examples of (meth)acrylate alkyl esters in which the number of carbon atoms of the alkyl or perfluoroalkyl group bonded to a non-carbonyl oxygen atom is in the range of 1 to 5 may include at least one of the following: alkyl acrylates, such as at least one of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and tert-butyl acrylate; 2-(perfluoroalkyl)ethyl acrylates, such as 2-(perfluorobutyl)ethyl acrylate and 2-(perfluoropentyl)ethyl acrylate; alkyl methacrylates, such as at least one of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and tert-butyl methacrylate; and 2-(perfluoroalkyl)ethyl methacrylates, such as at least one of 2-(perfluorobutyl)ethyl methacrylate, 2-(perfluoropentyl)ethyl methacrylate, and 2-(perfluoroalkyl)ethyl methacrylate.

[0095] Other (meth)acrylate alkyl esters may include: alkyl acrylates in which the alkyl group bonded to a non-carbonyl oxygen atom has a carbon number in the range of 6 to 18, such as n-hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, and isobornyl acrylate; alkyl methacrylates in which the alkyl group bonded to a non-carbonyl oxygen atom has a carbon number in the range of 6 to 18, such as n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecanyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, and cyclohexyl methacrylate; and 2-(perfluoroalkyl)ethyl acrylates in which the alkyl group bonded to a non-carbonyl oxygen atom has a carbon number in the range of 6 to 18, such as acrylic acid. 2-(perfluorohexyl)ethyl acrylate, 2-(perfluorooctyl)ethyl acrylate, 2-(perfluorononyl)ethyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluorododecyl)ethyl acrylate, 2-(perfluorotetradecyl)ethyl acrylate, 2-(perfluorohexadecyl)ethyl acrylate; and 2-(perfluoroalkyl)ethyl methacrylates wherein the alkyl group bonded to a non-carbonyl oxygen atom has a carbon number in the range of 6 to 18, such as 2-(perfluorohexyl)ethyl methacrylate, 2-(perfluorooctyl)ethyl methacrylate, 2-(perfluorononyl)ethyl methacrylate, 2-(perfluorodecyl)ethyl methacrylate, 2-(perfluorododecyl)ethyl methacrylate, 2-(perfluorotetradecyl)ethyl methacrylate, 2-(perfluorohexadecyl)ethyl methacrylate.

[0096] The structural units derived from (meth)acrylic acid or (meth)acrylate may include, independently or in combination, structural units represented by Formula 5, Formula 6, and Formula 7. When the above structural units are included, the total amount of the structural units represented by Formula 5, Formula 6, and Formula 7 may be included in a molar ratio in the range of about 10:1 to 1:1 (e.g., 6:1 to 1:1, e.g., 3:1 to 1:1).

[0097] (Meth)acrylic adhesives can be represented by, for example, the following chemical formula 8.

[0098] Chemical formula 8:

[0099]

[0100] In chemical formula 8,

[0101] R 1 R 2 R 12 R 13 R 16 and R 17Each is independently or includes hydrogen or methyl,

[0102] R 18 is or includes OR or O - [[ID=z]]M + , R is or includes hydrogen or a C1-C6 alkyl group, and M is or includes an alkali metal,

[0103] L 2 is or includes at least one of a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C6-C20 arylene group, or a substituted or unsubstituted C3-C20 heterocyclic group,

[0104] b is an integer within the range of 0 to z,

[0105] M is or includes an alkali metal,

[0106] l, m, and n represent the molar ratios of the respective units.

[0107] The alkali metal can be or include at least one of lithium, sodium, potassium, rubidium, or cesium.

[0108] For example, in Chemical Formula 8, l + m + n can be equal to 1. In addition, 0.05 ≤ (l + n) ≤ 0.45, 0.55 ≤ m ≤ 0.95; for example, 0.8 ≤ m ≤ 0.9, 0 < l ≤ 0.4, 0 < n ≤ 0.1; 0.8 ≤ m ≤ 0.9, 0 < l ≤ 0.1 and 0 < n ≤ 0.1; or 0.8 ≤ m ≤ 0.9, 0.01 ≤ l ≤ 0.1 and 0.01 ≤ n ≤ 0.

[0109] For example, in Chemical Formula 8, L 2 can be or include a substituted or unsubstituted C1-C10 alkylene group, and b can be or equal to 1.

[0110] In the (meth)acrylic binder, relative to 100 mol% of the total amount of (meth)acrylamide sulfonic acid structural units, the structural units substituted with an alkali metal (M + ) can be present in an amount within the range of about 50 mol% to about 100 mol% (for example, 60 mol% to 90 mol% or 70 mol% to 90 mol%). When the above range is satisfied, the (meth)acrylic binder and the separator including the (meth)acrylic binder can exhibit desired or improved adhesion, heat resistance, and oxidation resistance.

[0111] It should be noted that there is an unclear "z" in the original text in item . This translation is based on the existing content as accurately as possible. If there is an error in the original text, it may affect the accuracy of the translation.(Meth)acrylic adhesives may also include units other than those described above. For example, (meth)acrylic adhesives may also include units derived from alkyl (meth)acrylates, units derived from dienes, units derived from styrene, units containing esters, units containing carbonate groups, or combinations thereof.

[0112] (Meth)acrylic adhesives can take various forms, such as alternating polymers in which the above-mentioned units are alternately distributed, random polymers in which the above-mentioned units are randomly distributed, or graft polymers in which some of the structural units are grafted.

[0113] The weight-average molecular weight of (meth)acrylic adhesives can range from about 350,000 g / mol to about 970,000 g / mol (e.g., 450,000 g / mol to 970,000 g / mol or 450,000 g / mol to 700,000 g / mol). When the weight-average molecular weight of the (meth)acrylic adhesive meets the above range, the (meth)acrylic adhesive and the membrane comprising the (meth)acrylic adhesive can exhibit desired or improved adhesion, heat resistance, and air permeability. "Weight-average molecular weight" can be or includes the average molecular weight converted from polystyrene as measured using gel permeation chromatography.

[0114] (Meth)acrylic binders can be prepared by a variety of known methods, including emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization.

[0115] (Meth)acrylic adhesives can be prepared by solution polymerization.

[0116] According to one example embodiment, (meth)acrylic adhesives may be included in the coating layer of a diaphragm in the form of a film.

[0117] The content of (meth)acrylic binders can range from about 30 wt% to about 70 wt% (e.g., 30 wt% to 60 wt%, or 40 wt% to 60 wt%) of the total amount of (meth)acrylic binders, crosslinking agents, and carboxyl cellulose or their salts, for example, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, etc. of the total amount of (meth)acrylic binders, crosslinking agents, and carboxyl cellulose or their salts. 0wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt%. Within the above range, the diaphragm can exhibit improved heat resistance in the electrolyte.

[0118] Crosslinking agents include aziridine crosslinking agents.

[0119] Aziridine crosslinking agents can crosslink (meth)acrylic acid binders, and enable the diaphragm to achieve the dry shrinkage range and the shrinkage range in the electrolyte.

[0120] Aziridine crosslinking agents can be or include aziridine crosslinking agents with bifunctional or more functional groups. Here, "bifunctional or more functional groups" means that there are two or more aziridine groups in the molecule. According to an example embodiment, aziridine crosslinking agents can be or include aziridine crosslinking agents with bifunctional or trifunctional groups.

[0121] For example, aziridine crosslinking agents may include one or more of N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-(methylenedi-p-phenylene)bis(aziridine-1-carboxamide), triethylene melamine, 1,1-isophthaloylbis(2-methylaziridine), tri(1-aziridine)phosphine oxide, N,N-hexamethylene-bis(aziridinecarboxamide), trimethylolpropane tris(2-methyl-1-aziridine propionate), trimethylolpropane tris(β-N-aziridine) propionate, and pentaerythritol tris(3-(1-aziridine) propionate).

[0122] In contrast to adhesives such as (meth)acrylic adhesives and carboxyalkyl cellulose or its salts, crosslinking agents such as aziridine crosslinking agents may be included in appropriate amounts.

[0123] According to one example embodiment, the content of the crosslinking agent can be in the range of about 5 wt% to 30 wt%, for example, 10 wt% to 30 wt% or 10 wt% to 20 wt%, of the total amount of (meth)acrylic binder, crosslinking agent and carboxyl cellulose or salt thereof, such as 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%. Within the above range, the diaphragm can exhibit the effect of improved heat resistance in the electrolyte.

[0124] Compared to adhesives such as (meth)acrylic adhesives, crosslinking agents such as aziridine crosslinking agents may be included in appropriate amounts. For example, relative to 100 parts by weight of a (meth)acrylic adhesive, the content of the crosslinking agent can be in the range of about 5 parts by weight to about 50 parts by weight, for example, 10 parts by weight to 50 parts by weight or 10 parts by weight to 40 parts by weight, such as 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, etc. The amounts are: 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 37 parts by weight, 38 parts by weight, 39 parts by weight, 40 parts by weight, 41 parts by weight, 42 parts by weight, 43 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 47 parts by weight, 48 parts by weight, 49 parts by weight, and 50 parts by weight. Within the above range, the diaphragm can exhibit heat resistance.

[0125] Carboxyalkyl cellulose or its salts have a cyclic structure in the molecule and a carboxyl group in the molecule. This can react with crosslinking agents to increase the modulus of the coating, which can easily reduce the drying shrinkage and the shrinkage in the electrolyte.

[0126] Carboxyalkyl cellulose can be or includes, for example, carboxymethyl cellulose.

[0127] Salts of carboxyalkyl cellulose can be or include, for example, monovalent metal salts of carboxyalkyl cellulose, such as sodium salts of carboxyalkyl cellulose.

[0128] Carboxyalkyl cellulose or its salts may be included in appropriate amounts, relative to adhesives (e.g., (meth)acrylic adhesives) and crosslinking agents.

[0129] According to one example embodiment, the content of carboxyalkyl cellulose or its salt can be from about 20 wt% to about 70 wt% of the total amount of (meth)acrylic binder, crosslinker and carboxyalkyl cellulose or its salt, for example, in the range of 20 wt% to 65 wt%, 20 wt% to 60 wt%, 30 wt% to 70 wt%, 30 wt% to 60 wt% or 40 wt% to 60 wt%, for example, it can be 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt% of the total amount of (meth)acrylic binder, crosslinker and carboxyalkyl cellulose or its salt, for example, it can be 31 wt% to 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt% of the total amount of (meth)acrylic binder, crosslinker and carboxyalkyl cellulose or its salt, for example, it can be 31 wt%. The diaphragm can improve the heat resistance of the electrolyte within the ranges of t%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, and 70wt%.

[0130] The filler may include fillers having a particle size (D100) of about 0.7 μm or smaller. Within the aforementioned range, the dry shrinkage rate and the shrinkage rate in the electrolyte can be achieved in combinations of (meth)acrylic binders, crosslinking agents, carboxyalkyl cellulose, or salts thereof. For example, the filler may have a particle size (D100) in the range of about 0.1 μm to about 0.7 μm or 0.5 μm to 0.7 μm, such as about 0.01 μm, about 0.05 μm, about 0.1 μm, about 0.15 μm, about 0.2 μm, about 0.25 μm, about 0.3 μm, about 0.35 μm, about 0.4 μm, about 0.45 μm, about 0.5 μm, about 0.55 μm, about 0.6 μm, about 0.65 μm, and about 0.7 μm.

[0131] According to one example embodiment, the particle size (D50) of the filler can be about 0.4 μm or smaller, such as 0.35 μm or smaller, 0.3 μm or smaller, or 0.1 μm to 0.3 μm. Within the above range, the diaphragm can exhibit improved heat resistance.

[0132] According to one example embodiment, the content of fillers with a particle size (D100) of 0.7 μm or smaller can be about 95 wt% or more of the total filler in the coating, for example, 95 wt% to 100 wt%, 98 wt% to 100 wt%, or 100 wt%. Within the above range, the effect of a diaphragm can be easily achieved.

[0133] According to one example embodiment, the filler may not be surface modified.

[0134] The filler may be or includes, for example, inorganic fillers, organic fillers, organic / inorganic composite fillers, or combinations thereof. Inorganic fillers may be or include ceramic materials that can improve heat resistance. Inorganic fillers may include at least one of, for example, metal oxides, quasi-metal oxides, metal fluorides, metal hydroxides, or combinations thereof. Inorganic fillers may include at least one of, for example, Al₂O₃, SiO₂, TiO₂, SnO₂, CeO₂, MgO, NiO, CaO, GaO, ZnO, ZrO₂, Y₂O₃, SrTiO₃, BaTiO₃, Mg(OH)₂, boehmite, or combinations thereof, but this disclosure is not limited thereto. Organic fillers may include acrylic compounds, imide compounds, amide compounds, or combinations thereof, but this disclosure is not limited thereto. Organic fillers may have a core-shell structure, but this disclosure is not limited thereto. For example, the filler is or includes boehmite.

[0135] The filler can be spherical, plate-shaped, cubic, or amorphous. For example, the filler can be cubic and can have a significantly low shrinkage rate.

[0136] The filler may be included in an appropriate amount relative to the binder (e.g., a (meth)acrylic binder). According to an example embodiment, the mass ratio of (meth)acrylic binder to filler may be in the range of about 1:10 to about 1:50, for example, 1:20 to 1:30. Within the above range, the diaphragm may exhibit improved heat resistance in the electrolyte.

[0137] The filler content can range from approximately 50 wt% to 99 wt%, 70 wt% to 99 wt%, 75 wt% to 99 wt%, 80 wt% to 99 wt%, 85 wt% to 99 wt%, 90 wt% to 99 wt%, or 95 wt% to 99 wt% of the total amount of the coating. When the filler content is within the above range, desired or improved heat resistance, durability, oxidation resistance, and safety can be exhibited.

[0138] The thickness of the coating layer can be in the range of about 0.01 μm to 20 μm, and within the above range, the thickness of the coating layer can be 1 μm to 10 μm, 1 μm to 5 μm or 1 μm to 3 μm.

[0139] The ratio of the coating thickness to the porous substrate thickness can be from about 0.05 to about 0.5, for example, in the range of 0.05 to 0.4, 0.05 to 0.3, or 0.1 to 0.2. Within the above range, the membrane can exhibit desired or improved permeability, heat resistance, and adhesion. Here, when the coating is formed on only one surface of the porous substrate, "coating thickness" refers to the thickness of one coating layer, and when the coating is formed on both surfaces of the porous substrate, the thickness refers to the total thickness of the two coating layers.

[0140] Adhesive layer

[0141] The adhesive layer comprises a cross-linked (meth)acrylic adhesive. The cross-linked (meth)acrylic adhesive can reduce moisture content, thereby further reducing membrane shrinkage and providing the desired or improved safety for batteries exposed to heat.

[0142] Crosslinked (meth)acrylic adhesives can be highly crosslinked to improve heat resistance, thereby reducing or inhibiting the shrinkage of porous substrates at high temperatures. According to one example embodiment, the adhesive may include at least one of acrylate compounds or derivatives thereof, diallyl phthalate compounds or derivatives thereof, polyimide compounds or derivatives thereof, and polyurethane compounds or derivatives thereof.

[0143] For example, crosslinked (meth)acrylate adhesives may be or include crosslinked polymethyl methacrylate particles. Crosslinked (meth)acrylate adhesives can be prepared by conventional methods known in the art. Crosslinked polymer fillers can be prepared by adding a crosslinking agent during the monomer polymerization step.

[0144] Crosslinked (meth)acrylic adhesives can be particulate and can have a particle size (D50) of about 0.7 μm or smaller, such as 0.5 μm or smaller, or 0.2 μm to 0.7 μm. Within the above range, an adhesive layer with a substantially uniform thickness can be formed, thereby reducing the thickness of the separator and providing the desired or improved safety for batteries exposed to heat.

[0145] The adhesive can be applied at approximately 0.01 g / m³. 2 Up to 0.5g / m 2 For example, 0.06g / m 2 Up to 0.25g / m 2 Or 0.07g / m 2 Up to 0.21g / m 2 The loading amount is coated onto the surface of the negative electrode (e.g., the surface of the coating layer) within the range described above. When within the above range, the dry bending strength of the diaphragm can be easily improved.

[0146] Porous substrate

[0147] Porous substrates can be or include substrates having multiple pores and are commonly used in electrochemical devices. Porous substrates can be, but are not limited to, polymer films formed from or comprising any one polymer or copolymers or mixtures of two or more of them, such polymers being or including at least one of polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, glass fiber, Teflon, and polytetrafluoroethylene.

[0148] The porous substrate can be or includes, for example, a polyolefin substrate comprising polyolefins, and the polyolefin substrate contributes to improved battery safety due to desired or improved shutdown functionality. The polyolefin substrate can be or includes at least one of the following: for example, a polyethylene monolayer membrane, a polypropylene monolayer membrane, a polyethylene / polypropylene bilayer membrane, a polypropylene / polyethylene / polypropylene trilayer membrane, and a polyethylene / polypropylene / polyethylene trilayer membrane. Furthermore, the polyolefin resin can include non-olefin resins other than olefin resins or copolymers of olefin monomers and non-olefin monomers.

[0149] The porous substrate can have a thickness in the range of about 1 μm to about 40 μm, for example, 1 μm to 30 μm, 1 μm to 20 μm, or 5 μm to 15 μm.

[0150] A separator for a rechargeable lithium battery according to an example embodiment can exhibit desired or improved permeability, for example, less than about 200 sec / 100cc, 190 sec / 100cc or less, or 180 sec / 100cc or less. For example, the separator can have a permeability value of less than about 40 sec / 100cc·1μm per unit thickness, for example, 30 sec / 100cc·1μm or less, or 25 sec / 100cc·1μm or less. Here, permeability is the time (in seconds) it takes for 100cc of air to pass through a unit thickness of the separator. Permeability per unit thickness can be obtained by measuring the permeability of the total thickness of the separator and dividing the measured permeability by the thickness. Permeability can be measured by measuring the time (in seconds) required for 100cc of air to pass through using a permeability measuring device (Asahi Seiko, EG01-55-1MR).

[0151] A separator for a rechargeable battery according to an example embodiment can be formed by applying a composition for forming a coating layer to one or both surfaces of a porous substrate, and then drying and curing the resulting composition. Curing can be performed using conventional methods known to those skilled in the art.

[0152] Figure 1 This is a cross-sectional view of a separator for a rechargeable lithium battery according to an example embodiment. (Refer to...) Figure 1 The separator for a rechargeable lithium battery includes a porous substrate 1 and a laminate 2 consisting of a coating layer 5 and an adhesive layer 7 on two surfaces of the porous substrate 1. The laminate 2 may include: a coating layer (carboxyalkyl cellulose not shown) 5, comprising a filler 3 and a crosslinking product 4 of a (meth)acrylic binder and a crosslinking agent; and an adhesive layer 7, located on the coating layer 5, comprising an adhesive 6.

[0153] Rechargeable lithium batteries

[0154] According to one example embodiment, a rechargeable lithium battery includes a separator, a positive electrode, and a negative electrode for the rechargeable lithium battery.

[0155] The separator used in rechargeable lithium batteries is described above. The separator for rechargeable lithium batteries can be located between the positive and negative electrodes.

[0156] The positive electrode for a rechargeable lithium-ion battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer may include positive electrode active material and may also include a binder and / or a conductive material. For example, the positive electrode may also include additives capable of constituting a sacrificial positive electrode.

[0157] The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, at least one of lithium and a composite oxide of a metal such as or including at least one of cobalt, manganese, nickel and combinations thereof may be used.

[0158] The composite oxide can be or includes lithium transition metal composite oxides. Examples of composite oxides may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, or combinations thereof.

[0159] As an example, the following compounds, represented by any of the following chemical formulas, can be used. Li a A 1-b X b O 2- c D c(0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, and 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); or Li a FePO4 (0.90≤a≤1.8).

[0160] In the above chemical formulas, A is or includes at least one of Ni, Co, Mn, or combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or combinations thereof; D is or includes at least one of O, F, S, P, or combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; and L 1 It is or includes at least one of Mn, Al, or combinations thereof.

[0161] The positive electrode active material can be, or includes, for example, a high-nickel positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal complex oxide. The high-nickel positive electrode active material has a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be used in high-capacity, high-density rechargeable lithium batteries.

[0162] Based on a 100 wt% positive electrode active material layer, the amount of positive electrode active material can range from about 90 wt% to about 99.5 wt%. Based on a 100 wt% positive electrode active material layer, the amounts of binder and conductive material can each range from about 0.5 wt% to about 5 wt%.

[0163] The binder causes the positive electrode active material particles to adhere to each other and to adhere the positive electrode active material to the current collector. As a non-limiting example, examples of binders may include at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0164] Conductive materials can impart electrical conductivity (e.g., electroconductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in a battery. Examples of conductive materials can include: carbon-based materials, such as at least one of natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, comprising at least one of copper, nickel, aluminum, silver, etc., and in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0165] Al can be used as a current collector, but the current collector is not limited thereto.

[0166] The negative electrode for a rechargeable lithium battery may include a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer may include a negative electrode active material, and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0167] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of the negative electrode active material, from about 0.5 wt% to about 5 wt% of the binder, and from about 0 wt% to about 5 wt% of the conductive material.

[0168] The negative electrode active material may include at least one of a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, or a transition metal oxide.

[0169] The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Crystalline carbon may be graphite, such as natural graphite or artificial graphite that is amorphous, flaky, lamellar, spherical, or fibrous. Amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0170] The lithium metal alloy includes an alloy of lithium and a metal such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0171] The material capable of doping / de-doping lithium may be or include a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is or includes at least one of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and a combination thereof). The Sn-based negative electrode active material may include at least one of Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0172] Silicon-carbon composites can be or include composites of silicon and amorphous carbon. According to example embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) in which primary silicon particles are assembled, and an amorphous carbon coating layer (shell) on the surface of the secondary particles. Amorphous carbon may also be present between the primary silicon particles, and, for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed within an amorphous carbon matrix.

[0173] Silicon-carbon composites may also include crystalline carbon. For example, a silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer on the surface of the core.

[0174] Si-based or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0175] The binder can adhere the negative electrode active material particles to each other and also adhere the negative electrode active material to the current collector. The binder can include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0176] Non-aqueous adhesives may include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0177] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0178] When an aqueous binder is used as the negative electrode binder, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may include at least one of Na, K, or Li.

[0179] Dry adhesives can be or include fibrous polymeric materials. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0180] Conductive materials can impart electrical conductivity (e.g., electroconductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in a battery. Non-limiting examples of conductive materials may include: carbon-based materials, such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., and in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0181] The negative electrode current collector may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

[0182] Rechargeable lithium batteries may also include an electrolyte.

[0183] Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0184] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0185] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof.

[0186] Carbonate solvents may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0187] Ester solvents may include at least one of the following: methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0188] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include at least one of ethanol, isopropanol, etc. Aprotic solvents may include: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane; etc.

[0189] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0190] Furthermore, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0191] Lithium salts dissolved in organic solvents supply lithium ions in batteries, enabling rechargeable lithium batteries to operate and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are integers in the range of 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0192] According to one example embodiment, a positive electrode, a negative electrode, and a separator can be formed into a stacked electrode assembly. The stacked electrode assembly includes a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. The separator has a continuous sheet shape and can be folded in a first direction to surround the positive electrode and in a second direction opposite to the first direction to surround the negative electrode.

[0193] Figure 2 This is a conceptual diagram of a stacked electrode assembly according to an example embodiment.

[0194] Reference Figure 2 The stacked electrode assembly includes a positive electrode 110 with a positive electrode terminal 111, a negative electrode 120 with a negative electrode terminal 121, and a diaphragm 130 located between the positive electrode 110 and the negative electrode 120. (Refer to...) Figure 2 The diaphragm 130 has a continuous sheet shape and is folded alternately in a first direction and a second direction opposite to it. Therefore, the vertical cross-section of the diaphragm 130 in the stacked electrode assembly can have a cross shape or a Z-shaped shape.

[0195] Rechargeable lithium batteries can be classified according to their shape, such as cylindrical batteries, prismatic batteries, pouch batteries, or coin-shaped batteries. Figures 3 to 6This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 3 A cylindrical battery is shown. Figure 4 A prismatic battery is shown. Figure 5 and Figure 6 A pouch-type battery is shown. (See reference) Figures 3 to 6 The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode assembly 40 is housed within the housing 50. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 3 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. Figure 4 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative electrode terminal 22 connected to the negative electrode lead connector 21. For example... Figure 5 and Figure 6 As shown, the rechargeable lithium battery 100 may include Figure 6 The electrode terminal 70 shown may, for example, include... Figure 5 The positive electrode terminal 71 and negative electrode terminal 72 shown herein form an electrical path for guiding the current generated in the electrode assembly 40 to the outside of the rechargeable lithium battery 100.

[0196] As a non-limiting example, the rechargeable lithium battery according to the example embodiment can be used in, for example, automobiles, mobile phones and / or various types of electronic devices.

[0197] Examples and comparative examples of this disclosure are described below. However, the following examples are merely illustrative of this disclosure, and this disclosure is not limited thereto.

[0198] Preparation Example 1

[0199] Distilled water (6361 g), acrylic acid (1.0 mol), acrylamide (8.5 mol), potassium persulfate (0.01 mol), 2-acrylamido-2-methylpropanesulfonic acid (0.5 mol), and a 5 N aqueous solution of lithium hydroxide (total amount of 2-acrylamido-2-methylpropanesulfonic acid) were added to a 10 L four-necked flask equipped with a stirrer, thermometer, and condenser. The operation of reducing the internal pressure to 10 mmHg using a diaphragm pump and restoring the internal pressure to atmospheric pressure using nitrogen was repeated three times.

[0200] The reaction was carried out for 12 hours while maintaining the temperature of the reaction solution between 65°C and 70°C. After cooling to room temperature, the pH of the reaction solution was adjusted to between 7 and 8 using a 25% ammonia solution.

[0201] In this manner, poly(acrylic acid-co-lithium acrylate-co-acrylamide-co-2-acrylamido-2-methylpropanesulfonate lithium salt) was prepared. The molar ratio of acrylic acid + lithium acrylate, acrylamide, and 2-acrylamido-2-methylpropanesulfonate lithium salt was 10:85:5. After taking approximately 10 mL of the reaction solution (reaction product), the specific gravity (or proportion) of the non-volatile component was measured, and the result was 9.5 wt% (theoretical value: 10 wt%).

[0202] Preparation Example 2

[0203] Acrylic adhesives were prepared in the same manner as in Preparation Example 1, except that acrylamide and 2-acrylamido-2-methylpropanesulfonic acid were used instead of acrylic acid. The molar ratio of acrylamide to lithium 2-acrylamido-2-methylpropanesulfonic acid was 74:26. ​​The non-volatile component of the reaction solution was 9.0 wt% (theoretical value: 10 wt%).

[0204] Example 1

[0205] The acrylic binder prepared in Preparation Example 1 (in distilled water and 10 wt%) and boehmite (particle size (D100): 0.5 μm, particle size (D50): 0.2 μm, cubic type) as filler were mixed at an acrylic binder:filler mass ratio of 1:20 based on solid content, added to an aqueous solvent, and dispersed by grinding at 25°C for 30 minutes using a bead mill to prepare a dispersion.

[0206] Trimethylolpropane tris(2-methyl-1-aziridine propionate) (a trifunctional aziridine crosslinking agent) and carboxymethyl cellulose (CMC) were added to a dispersion, and water was added to bring the total solids content to 20 wt%, thereby preparing a composition for coating. Here, the content of acrylic binder:carboxymethyl cellulose:aziridine crosslinking agent was 45 parts by weight:45 parts by weight:10 parts by weight (total 100 parts by weight).

[0207] The two surfaces of a polyethylene-based membrane (thickness: 8 μm, SK, air permeability: 120 sec / 100 cc, needle penetration strength: 480 kgf) serving as a porous substrate were coated with a composition for forming a coating layer to a thickness of 1.5 μm using a molding method. The membrane was then dried in an oven at 80°C for 16 hours and aged to form the coating layer.

[0208] Both surfaces of the coating layer were coated with a cross-linked polymethyl methacrylate polymer (cross-linked PMMA, particle size (D50): 0.5 μm) as an adhesive to a thickness of 0.5 μm. The cross-linked polymethyl methacrylate polymer had been diluted to a solids content of 2 wt% and dried at 50°C for 10 minutes to form an adhesive layer with a total thickness of 1.0 μm (for the electrode plate, the loading rate (load per unit area) is 0.21 g / m²). 2 This allows for the manufacture of separators for rechargeable lithium batteries.

[0209] Examples 2 to 5

[0210] The diaphragm is manufactured in the same manner as in Example 1, except that the composition used for the coating layer and the loading of the adhesive layer are changed as shown in Table 1 below.

[0211] Example 6

[0212] The diaphragm was manufactured in the same manner as in Example 1, except that the adhesive used in Preparation Example 2 was used instead of the acrylic adhesive used in Preparation Example 1.

[0213] Comparison Example 1 to Comparison Example 3

[0214] The diaphragm is manufactured in the same manner as in Example 1, except that the composition used for the coating layer and the loading of the adhesive layer are changed as shown in Table 1 below.

[0215] Compare Example 4

[0216] The diaphragm is manufactured in the same manner as in Example 1, except that the composition used for the coating layer is changed as shown in Table 1 below, and no adhesive layer is formed.

[0217] Compare Example 5

[0218] The acrylic binder prepared in Preparation Example 1 (in distilled water and 10 wt%) and boehmite (particle size (D100): 0.5 μm, particle size (D50): 0.2 μm, cubic type) as filler were mixed at a solids content ratio of 1:20 (acrylic binder:filler) and placed in an aqueous solvent. The mixture was then dispersed by grinding at 25°C for 30 minutes using a bead mill to prepare a dispersion. Trimethylolpropane tris(2-methyl-1-aziridine propionate) and carboxymethyl cellulose (CMC) as aziridine crosslinking agents were added to the dispersion. Water was added to make the total solids content 20 wt%, and crosslinked polymethyl methacrylate polymer (crosslinked PMMA, particle size (D50): 0.5 μm) was included as a binder to prepare a composition for coating. Here, the content of acrylic binder:carboxymethyl cellulose:aziridine crosslinking agent was 45 parts by weight:45 parts by weight:10 parts by weight (total 100 parts by weight). Here, the content of cross-linked polymethyl methacrylate polymer in the composition used for the coating layer is 0.05 g / m² relative to the surface of the electrode plate. 2 .

[0219] A membrane is manufactured by coating two surfaces of a polyethylene-based membrane (thickness: 8 μm, SK, air permeability: 120 sec / 100 cc, needle penetration strength: 480 kgf) as a porous substrate with a composition for forming a coating layer to a thickness of 1.5 μm using a molding method. The membrane is then dried in an oven at 80 °C for 16 hours and aged to form the coating layer, thereby manufacturing a diaphragm.

[0220] Dry shrinkage rate (unit: %)

[0221] Samples were prepared by cutting the separators for rechargeable lithium batteries of the example and comparative examples into 8cm × 8cm dimensions. A 5cm × 5cm square was drawn on the surface of each sample. After placing the sample between paper or alumina powder, the sample was left to stand in an oven at 150°C for 1 hour. The shrinkage rate in each direction (MD and TD) was calculated by measuring the side dimensions of the drawn squares. The shrinkage rate was calculated according to Equation 1 below.

[0222] Equation 1:

[0223] Shrinkage rate = (L0-L1) / L0×100.

[0224] L0: Initial length of the diaphragm; L1: Length of the diaphragm after standing at 150°C for 1 hour.

[0225] Shrinkage rate in electrolyte (unit: %)

[0226] Samples were prepared by cutting the separators for rechargeable lithium batteries of the example and comparative examples into 8cm × 8cm dimensions. A 5cm × 5cm square was drawn on the surface of each sample.

[0227] A positive electrode slurry was prepared by mixing 97 wt% LiCoNiAl as the positive electrode active material, 1.5 wt% carbon nanotubes as the conductive material, and 1.5 wt% polyvinyl fluoride and adding water.

[0228] A positive electrode is manufactured by applying the prepared positive electrode paste onto an aluminum foil, drying it, and then rolling the prepared positive electrode paste under pressure.

[0229] A negative electrode active material slurry was prepared by mixing 97.4 wt% of a negative electrode active material, 1.0 wt% of carboxymethyl cellulose, 1.5 wt% of styrene-butadiene rubber, and 0.1 wt% of carbon nanotubes as a conductive material. A silicon-based negative electrode active material was used. The negative electrode was manufactured by coating the prepared negative electrode slurry onto copper foil and then drying and rolling it.

[0230] A sample was placed between the positive and negative electrodes to create three sets of positive electrode-sample-negative electrode stacks, which were then placed in a bag. The stacks were completely impregnated with 2g of electrolyte (containing 1.5M LiPF6 in ethylene carbonate, methyl ethyl carbonate, and dimethyl carbonate (volume ratio 30:50:20)), sealed, and then left to stand at 25°C for 12 hours. After the resulting product was left to stand in an oven at 150°C for 1 hour, the sample was removed to measure the side dimensions of a drawn square, and the shrinkage rate in each direction (MD and TD) was calculated. The shrinkage rate can be calculated according to Equation 1 above.

[0231] Dry bending strength (unit: N)

[0232] like Figure 7 As shown, the electrode core D is manufactured by sequentially stacking the positive electrode B, diaphragm A, negative electrode C, and diaphragm A in a zigzag pattern. Figure 8 As shown, the stacked electrode core D is placed between the upper clamp E and the lower clamp F, which are preheated to 75°C, and then pressed for 90 seconds using a hot press. The hot-pressed electrode core is then connected to the Nexygen Plus program and subjected to a 3-point bending test using a LloydUTM (Universal Testing Machine). Figure 8 As shown, the pole core D is placed on the lower clamps F located at the left and right ends, and the upper clamp E located in the middle is lowered at a specific speed to apply force. Then the force (N) at the break point of the pole core D is calculated.

[0233] Substrate cohesion (unit: N)

[0234] Tests were conducted according to Korean Industrial Standard KS-A-01107 (Test Methods for Adhesive Tapes and Sheets). Each diaphragm manufactured in the example and comparative examples was cut to a size of 3cm × 8cm (width × length). Adhesive tape (Nitto 31B) was placed on both surfaces of the diaphragm to form a sample. The sample was then pressed once using a compression roller with a 2kg load at a speed of 300mm / min via reciprocating motion. After pressing for 30 minutes, the sample was rotated 180° and peeled approximately 25mm. The diaphragm and the tape attached to one surface of the diaphragm were then fixed to the upper clamp of a tensile strength tester (Instron 1X / s Automated Material Tester-3343, Instron). The tape attached to the other surface of the diaphragm was fixed to the lower clamp, and a tensile test was performed at a tensile speed of 60mm / min. The pressure at which the adhesive layer and coating layer of the diaphragm peeled off from the porous substrate was measured.

[0235] Hot tip test (unit: mm)

[0236] like Figure 9 As shown, sample G is prepared by cutting the diaphragm into 5cm × 5cm dimensions, fixing the corners of sample G with magnet H, and placing the sample on fixture I. This will form a sample with a diameter... A rod J with a 2 mm tip is heated to 400 °C and penetrates the center of the sample surface. The diameter (mm) of the resulting hole is then measured.

[0237] Table 1:

[0238]

[0239] *CMC: Carboxymethyl cellulose

[0240] *Comparative Example 5: Acrylic adhesives are included in the coating layer.

[0241] As shown in Table 1 above, the example separator for lithium secondary batteries exhibits significantly low shrinkage in the electrolyte, as well as high dry flexural strength and substrate bonding strength. Furthermore, when tested in a hot tip test, the example separator demonstrates a significantly low pore diameter length, enabling it to provide the desired or improved safety in thermally exposed batteries. However, compared to the example described above, the separator of the comparative example did not provide the desired or improved performance.

[0242] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and various modifications may be made within the scope of the claims, detailed description and drawings, and these modifications are obviously also within the scope of the present disclosure.

[0243] Explanation of reference numerals in the attached figures:

[0244] 1: Diaphragm

[0245] 2: Porous substrate

[0246] 3: Packing material

[0247] 4: Crosslinking products of (meth)acrylic adhesives and crosslinking agents

[0248] 100: Rechargeable lithium battery

[0249] 10: Positive electrode

[0250] 11: Positive electrode lead connector

[0251] 12: Positive electrode terminal

[0252] 20: Negative electrode

[0253] 21: Negative electrode lead connector

[0254] 22: Negative electrode terminal

[0255] 30: Diaphragm

[0256] 40: Electrode assembly

[0257] 50: Casing

[0258] 60: Sealing component

[0259] 70: Electrode connector

[0260] 71: Positive electrode connector

[0261] 72: Negative electrode connector.

Claims

1. A separator for a rechargeable lithium battery, the separator comprising: Porous substrate; A coating layer on at least one surface of the porous substrate; as well as An adhesive layer is placed on one surface of the coating layer. The coating layer comprises: a binder, a crosslinking agent, a crosslinking product of carboxyalkyl cellulose or its salts; and a filler. The adhesive comprises a (meth)acrylic adhesive, wherein the (meth)acrylic adhesive comprises a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or a salt thereof. The crosslinking agent includes aziridine crosslinking agents, and The adhesive layer comprises (meth)acrylic adhesives.

2. The diaphragm according to claim 1, wherein, The coating layer comprises a composition containing the (meth)acrylic binder, the crosslinking agent, the carboxyl cellulose or a salt thereof, and the filler.

3. The diaphragm according to claim 1, wherein, The carboxyalkyl cellulose or its salts include carboxymethyl cellulose or its salts.

4. The diaphragm according to claim 1, wherein, The content of the carboxyalkyl cellulose or its salt is in the range of 20 wt% to 70 wt% of the total amount of the (meth)acrylic binder, the crosslinking agent and the carboxyalkyl cellulose or its salt.

5. The diaphragm according to claim 1, wherein, The aziridine crosslinking agents include one or more of N,N'-toluene-2,4-bis(1-aziridinecarboxamide), N,N'-(methylenedi-p-phenylene)bis(aziridine-1-carboxamide), triethylene melamine, 1,1-isophthaloylbis(2-methylaziridine), tri(1-aziridine)phosphine oxide, N,N-hexamethylene-bis(aziridinecarboxamide), trimethylolpropane tris(2-methyl-1-aziridine propionate), trimethylolpropane tris(β-N-aziridine) propionate, and pentaerythritol tris(3-(1-aziridine) propionate).

6. The diaphragm according to claim 1, wherein, The packing material includes packing material with a particle size D100 of 0.7 μm or smaller.

7. The diaphragm according to claim 1, wherein, The packing material is one of the following: spherical packing, plate packing, cubic packing, and amorphous packing.

8. The diaphragm according to claim 1, wherein, The mass ratio of the (meth)acrylic adhesive to the filler is in the range of 1:10 to 1:

50.

9. The diaphragm according to claim 1, wherein: Based on the total amount of the (meth)acrylic binder, the crosslinking agent, and the carboxyl cellulose or its salt, The content of the (meth)acrylic adhesive is in the range of 30 wt% to 70 wt%. The content of the crosslinking agent is in the range of 5 wt% to 30 wt%, and The content of the carboxyalkyl cellulose or its salt is in the range of 20 wt% to 70 wt%.

10. The diaphragm according to claim 1, wherein, The first structural unit is represented by chemical formula 1: Chemical Formula 1: In chemical formula 1, R 1 and R 2 Each independently includes either hydrogen or methyl, and The second structural unit is represented by at least one of chemical formulas 2, 3, 4, and combinations thereof: Chemical formula 2: Chemical formula 3: Chemical formula 4: Among them, in chemical formulas 2 to 4, R 10 R 11 R 12 R 13 R 14 and R 15 Each independently includes either hydrogen or methyl. L 1 L 2 and L 3 Each independently comprises a substituted or unsubstituted C1 to C10 alkylene group, a substituted or unsubstituted C3 to C20 cycloalkylene group, a substituted or unsubstituted C6 to C20 arylene group, or a substituted or unsubstituted C3 to C20 heterocyclic group. a, b, and c are all independent integers in the range of 0 to 2, and M includes alkali metals.

11. The diaphragm according to claim 1, wherein, The (meth)acrylic adhesive also includes a third structural unit derived from (meth)acrylic acid or (meth)acrylate.

12. The diaphragm according to claim 11, wherein, The third structural unit is represented by at least one of chemical formulas 5, 6, 7, and combinations thereof: Chemical formula 5: Chemical Formula 6: Chemical Formula 7: Among them, in chemical formulas 5 to 7, R 3 R 4 R 6 R 7 R 8 and R 9 Each independently includes either hydrogen or methyl. R 5 Including substituted or unsubstituted C1 to C20 alkyl groups, and M includes alkali metals.

13. The diaphragm according to claim 1, wherein, The adhesive is at a concentration of 0.01 g / m 2 Up to 0.5g / m 2 The load within the range is included on one of the surfaces of the coating.

14. The diaphragm according to claim 1, wherein, The adhesive comprises cross-linked polymethyl methacrylate particles having a particle size D50 of 0.7 μm or smaller.

15. A rechargeable lithium battery, said rechargeable lithium battery comprising: Positive electrode; negative electrode; as well as The separator for a rechargeable lithium battery according to any one of claims 1 to 14, between the positive electrode and the negative electrode.

16. The rechargeable lithium battery according to claim 15, wherein, The diaphragm has a continuous sheet shape, and the diaphragm is folded in a first direction to surround the positive electrode and in a second direction opposite to the first direction to surround the negative electrode.

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