Separator for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

Examples of the present disclosure include a separator for a rechargeable lithium battery and a rechargeable lithium battery including the same. A separator for a rechargeable lithium battery includes a porous substrate and a coating layer on at least one surface of the porous substrate. The coating 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) acryloyl-based binder including a first structural unit derived from (meth) acrylamide and a second structural unit derived from (meth) acrylamidosulfonic acid or a salt thereof. The cross-linking agent comprises one or more of an aziridine cross-linking agent and a carbodiimide cross-linking agent.

Description

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0058158, filed on April 30, 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 may be beneficial.

[0004] Rechargeable lithium batteries typically include positive and negative electrodes containing active materials capable of inserting and deintercalating lithium ions, and generate electrical energy through redox reactions during the insertion and deintercalation of lithium ions into and from the positive and negative electrodes.

[0005] Rechargeable lithium batteries may include a separator between the positive and negative electrodes. The separator is impregnated with an electrolyte. It may be advantageous to keep the separator in its original shape without subjecting it to thermal shrinkage in the electrolyte to ensure battery stability. Summary of the Invention

[0006] One example embodiment includes a separator for a rechargeable lithium battery that has low dry shrinkage and low shrinkage in the electrolyte, thereby increasing battery stability.

[0007] Another example embodiment includes a rechargeable lithium battery comprising a separator for a rechargeable lithium battery.

[0008] Example embodiments include a separator for rechargeable lithium batteries.

[0009] 1. A separator for a rechargeable lithium-ion battery, the separator comprising a porous substrate and a coating on at least one surface of the porous substrate. The coating comprises a binder, a crosslinking agent, and a crosslinking product of carboxyalkyl cellulose or a salt thereof, as well as a filler. The binder comprises a (meth)acryloyl-based binder comprising a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamidosulfonic acid or a salt thereof. The crosslinking agent comprises one or more of aziridine crosslinking agents and carbodiimide crosslinking agents.

[0010] 2. In 1, the coating is formed by or includes a composition comprising (meth)acryloyl-based binders, crosslinking agents, carboxyl cellulose or salts thereof, and fillers.

[0011] 3. In 1-2, wherein carboxyalkyl cellulose or its salts include carboxymethyl cellulose or its salts.

[0012] 4. In 1-3, wherein carboxyalkyl cellulose or its salts are included in an amount ranging from about 20 wt% to about 70 wt% of the total amount of (meth)acryloyl binders, crosslinking agents and carboxyalkyl cellulose or its salts.

[0013] 5. In 1-4, the aziridine crosslinking agent includes 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-aziridineyl)phosphine oxide, N,N-hexamethylene-bis(aziridinecarboxamide), trimethylolpropane tris(2-methyl-1-aziridine propionate), trimethylolpropane tris(β-N-aziridineyl)propionate, and pentaerythritol tris(3-(1-aziridineyl)propionate).

[0014] 6. In 1-5, the carbodiimide crosslinking agent includes one or more of monocarbodiimide compounds and polycarbodiimide compounds.

[0015] 7. In 1-6, the particle size D100 of the filler is about 1.0 μm or smaller.

[0016] 8. In 1-7, the packing material is generally spherical, generally plate-shaped, generally cubic, or amorphous.

[0017] 9. In 1-8, the filler is surface modified to have amino groups on its surface.

[0018] 10. In 1-9, the mass ratio of (meth)acryloyl binder to filler is in the range of about 1:10 to about 1:50.

[0019] 11. In 1-10, wherein, relative to the total amount of (meth)acryloyl binder, crosslinking agent and carboxyalkyl cellulose or salt thereof, the (meth)acryloyl binder is included in an amount ranging from about 30 wt% to about 70 wt%, the crosslinking agent is included in an amount ranging from about 5 wt% to about 30 wt%, and the carboxyalkyl cellulose or salt thereof is included in an amount ranging from about 20 wt% to about 65 wt%.

[0020] 12. In 1-11, the first structural unit is represented by the following chemical formula 1: Chemical Formula 1: .

[0021] In chemical formula 1, R 1 and R 2 Each is independently either hydrogen or methyl. The second structural unit is represented by any one of the following chemical formulas 2, 3, and 4, and combinations thereof: Chemical formula 2:

[0022] Chemical formula 3:

[0023] Chemical formula 4: , In chemical formulas 2 to 4, R 10 R 11 R 12 R 13 R 14 and R 15 Each is independently either hydrogen or methyl. L 1 L 2 and L 3 Each of these groups independently comprises or includes substituted or unsubstituted C1 to C10 alkylene groups, substituted or unsubstituted C3 to C20 cycloalkylene groups, substituted or unsubstituted C6 to C20 arylene groups, or substituted or unsubstituted C3 to C20 heterocyclic groups. a, b, and c are each an independent integer in the range of 0 to 2, and M is or includes alkali metals.

[0024] 13. In 1-12, wherein the (meth)acryloyl adhesive further comprises a third structural unit derived from (meth)acrylic acid or (meth)acrylate.

[0025] 14. In 1-13, the third structural unit is represented by any one or a combination of the following chemical formulas 5, 6, and 7: Chemical formula 5:

[0026] Chemical Formula 6:

[0027] Chemical Formula 7: .

[0028] In chemical formulas 5 to 7 R 3 R 4 R 6R 7 R 8 and R 9 Each is independently either hydrogen or methyl. R 5 It is or includes substituted or unsubstituted C1 to C20 alkyl groups, and M is or includes alkali metals.

[0029] 15. In 1-14, the coating has a thickness in the range of about 0.01 μm to about 20 μm.

[0030] Another example embodiment includes a rechargeable lithium battery.

[0031] A rechargeable lithium battery includes: a positive electrode; a negative electrode; and a separator for the rechargeable lithium battery, located between the positive and negative electrodes. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment.

[0033] Figures 2 to 5 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Detailed Implementation

[0034] 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.

[0035] Unless otherwise stated herein, when a component such as a layer, film, region, plate, etc., is described as being disposed "on" another component, it includes not only the case where the component is "directly" on the other component, but also the case where other components are present in between.

[0036] Unless otherwise stated herein, the singular may also include the plural. Additionally, unless otherwise stated, the term "A or B" may mean "including A, including B, or including both A and B".

[0037] In this specification, "combination thereof" may mean a mixture, stack, complex, copolymer, alloy, blend or reaction product of the components.

[0038] Unless otherwise defined herein, particle size may refer to average particle size. Alternatively, particle size refers to average particle size D100, which is the diameter of particles that constitute 100% of the total volume in a particle size distribution. Average particle size D100 can be measured by methods known to those skilled in the art, and can be measured, for example, using a particle size analyzer, transmission electron microscopy (TEM) images, or scanning electron microscopy (SEM) images. Alternatively, average particle size D100 can be obtained by the following steps: measuring particle size using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles in each particle size range, and then calculating the average particle size D100 from this data. Optionally, average particle size D100 can be measured using laser diffraction. When measuring average particle size by laser diffraction, for example, the average particle size D100 based on 100% particle size distribution in the measuring device can be calculated 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 MT 3000), and radiating ultrasound at approximately 28 kHz with an output power of 60 W.

[0039] In this specification, "particle size D50" refers to the particle size representing the diameter of particles that constitute 50% of the cumulative volume in the particle size distribution. This particle size distribution can be obtained by referring to the method described in "particle size D100" above.

[0040] In this specification, "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0041] In the following text, unless otherwise defined, “substitution” means that the hydrogen in a compound is substituted by at least one of the following substituents: 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 each independently hydrogen or C1 to C6 alkyl), thiobetaine (-RR'N) + (CH2) n SO3 - (where n is a natural number from 1 to 10) (where R and R' are each independently a C1 to C20 alkyl group), carboxybenzene group (-RR'N) + (CH2) n COO -(where n is a natural number from 1 to 10) (where R and R' are each independently C1 to C20 alkyl), azide (-N3), formamidinyl (-C(=NH)NH2), hydrazine (-NHNH2), hydrazine (-N(NH2)-), carbamoyl (-C(O)NH2), thiol (-SH), acyl (-C(=O)R, where R represents C1 to C6 alkyl, C1 to C6 alkoxy, or C6 to C12 aryl), carboxyl (-COOH) or its salt (-C(=O)OM, where M represents an organic or inorganic cation), sulfonic acid (-SO3H) or its salt (-SO3M, where M represents an organic or inorganic cation), phosphate (-PO3H2) or its salt (-PO3MH or -PO3M2, where M represents an organic or inorganic cation), and combinations thereof.

[0042] In the following description, C1 to C3 alkyl groups may be or include at least one of methyl, ethyl, or propyl. C1 to C10 alkylene groups may be or include at least one of, for example, C1 to C6 alkylene groups, C1 to C5 alkylene groups, or C1 to C3 alkylene groups, and may be or include at least one of, for example, methylene, ethylene, or propylene. C3 to C20 cycloalkylene groups may be or include at least one of, for example, C3 to C10 cycloalkylene groups or C5 to C10 cycloalkylene groups, for example, cyclohexylene. C6 to C20 arylene groups may be or include, for example, C6 to C10 arylene groups, for example, phenylene. C3 to C20 heterocyclic groups may be or include, for example, C3 to C10 heterocyclic groups, for example, pyridyl.

[0043] In the following text, “heterogeneous” means one or more heteroatoms including or containing at least one of N, O, S, Si and P.

[0044] In addition, in chemical formulas, symbols It refers to the part that is connected to the same or different atoms, groups or structural units.

[0045] 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, which can exist in either a cation or a neutral state.

[0046] In this specification, 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)”.

[0047] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it is intended 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%.

[0048] A separator for a rechargeable lithium battery according to an example embodiment includes: a porous substrate; and a coating located on at least one surface of the porous substrate, wherein the coating includes a binder, a crosslinking agent, and a crosslinking product of carboxyalkyl cellulose or a salt thereof, and a filler, the binder including a (meth)acryloyl-based binder comprising a first structural unit and a second structural unit, the first structural unit being derived from (meth)acrylamide, the second structural unit being derived from (meth)acrylamidosulfonic acid or a salt thereof, and the crosslinking agent including one or more of aziridine crosslinking agents and carbodiimide crosslinking agents.

[0049] According to one example embodiment, the coating may be formed by or comprise a composition including one or more of (meth)acryloyl binders, aziridine crosslinkers and carbodiimide crosslinkers, carboxyalkyl cellulose or a salt thereof, and fillers.

[0050] According to one example embodiment, the crosslinking product may be or include a thermally crosslinked product.

[0051] Because the coating comprises (meth)acryloyl-based binders, crosslinking agents, and crosslinking products of carboxyalkyl cellulose or their salts, as well as fillers, the separator for rechargeable lithium batteries can have significantly low dry shrinkage and electrolyte shrinkage. Specifically, a separator in which the coating is applied only to one surface of a porous substrate can also have significantly low dry shrinkage and electrolyte shrinkage.

[0052] According to one example embodiment, the dry shrinkage rate of the separator for a rechargeable lithium battery may be 5% or less in each of the longitudinal (MD) and transverse (TD) directions, and the shrinkage rate in the electrolyte in each of the MD and TD directions may be 15% or less, for example, 10% or less, or 5% or less.

[0053] According to one example embodiment, the separator for a rechargeable lithium-ion battery exhibits a significantly low shrinkage rate in the electrolyte. The shrinkage rate in the electrolyte can be determined by considering the application location of the separator in the rechargeable lithium-ion battery. The separator can be impregnated with the electrolyte. A separator with a low shrinkage rate in the electrolyte can increase battery stability by maintaining heat resistance without diminishing the mechanical properties of the (meth)acryloyl binder when the separator is impregnated with the electrolyte.

[0054] Membranes formed from or comprising compositions including (meth)acryloyl-based binders but excluding aziridine-based and carbodiimide-based crosslinking agents, or crosslinking agents other than aziridine-based and carbodiimide-based crosslinking agents, may not meet the shrinkage range in the electrolyte described above.

[0055] According to one example embodiment, one or more of aziridine crosslinking agents and carbodiimide crosslinking agents may be included in an amount of about 95 wt% or more of the total crosslinking agent in the composition, for example, in the range of 98 wt% to 100 wt%, or 100 wt%.

[0056] Membranes formed from or comprising a composition including aziridine crosslinking agents or carbodiimide crosslinking agents and fillers but excluding (meth)acryloyl binders, or including binders other than (meth)acryloyl binders, may not meet the above-mentioned dry shrinkage and electrolyte shrinkage ranges.

[0057] According to one example embodiment, (meth)acryloyl-based adhesives may be included in an amount of about 95 wt% or more of the total adhesive in the composition, for example, in the range of 98 wt% to 100 wt%, or in an amount of 100 wt%.

[0058] Membranes formed from or comprising compositions that do not include carboxyl cellulose or its salts may not meet the above-mentioned dry shrinkage and electrolyte shrinkage ranges.

[0059] coating The coating is or includes a heat-resistant layer and includes a (meth)acryloyl-based adhesive, which comprises a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or a salt thereof.

[0060] According to one example embodiment, in 100 mol% of (meth)acryloyl-based binders, the total amount of the first and second structural units can be about 95 mol% or more, for example, in the range of 95 mol% to 100 mol% or 100 mol%.

[0061] (Methacryl)acryloyl adhesives may also include a third structural unit derived from (meth)acrylic acid or (meth)acrylate.

[0062] According to one example embodiment, in 100 mol% of (meth)acryloyl-based binders, the total amount of the first structural unit, the second structural unit, and the third structural unit may be about 95 mol% or more, for example, in the range of 95 mol% to 100 mol% or may be 100 mol%.

[0063] (Methacrylamide)-based binders are or include water-based heat-resistant binders and can fix fillers to porous substrates, providing adhesive strength so that the coating adheres to the porous substrate and electrodes, and helping to increase the heat resistance, permeability and oxidation resistance of the diaphragm.

[0064] The first structural unit, derived from (meth)acrylamide, has an amide functional group (-(C=O)-NH2) within the structural unit. The -(C=O)-NH2 functional group can increase adhesion to porous substrates and electrodes, and further enhance the heat resistance of the membrane by forming hydrogen bonds with the -OH functional groups of the filler to more firmly fix the inorganic filler in the coating.

[0065] The second structural unit derived from (meth)acrylamide sulfonic acid or its salt may include bulky functional groups, thereby reducing the mobility of binders containing bulky functional groups and enhancing the heat resistance of the membrane.

[0066] The third structural unit, derived from (meth)acrylic acid or (meth)acrylate, can be configured to anchor the filler to the porous substrate and provide adhesive strength, enabling the coating to adhere to both the porous substrate and the electrode, and contributing to increased heat resistance and permeability of the diaphragm. Furthermore, the structural unit, derived from (meth)acrylic acid or (meth)acrylate, can include carboxyl functional groups (-C(=O)O-) within the structural unit, thereby contributing to improved dispersibility of the coating slurry.

[0067] In 100 mol% of (meth)acryloyl-based adhesives, the first structural unit is present at about 55 mol% to about 95 mol% (e.g., 55 mol%, 56 mol%, 57 mol%, 58 mol%, 59 mol%, 60 mol%, 61 mol%, 62 mol%, 63 mol%, 64 mol%, 65 mol%, 66 mol%, 67 mol%, 68 mol%, 69 mol%, 70 mol%, 71 mol%, 72 mol%, 73 mol%, 74 mol%, 75 mol%, 76 mol%, 77 mol%). The amounts included are within the ranges of 78 mol%, 79 mol%, 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, 85 mol%, 86 mol%, 87 mol%, 88 mol%, 89 mol%, 90 mol%, 91 mol%, 92 mol%, 93 mol%, 94 mol%, and 95 mol%), 70 mol% to 95 mol%, 75 mol% to 95 mol%, 80 mol% to 95 mol%, or 80 mol% to 90 mol%.

[0068] In a 100 mol% (meth)acryloyl-based binder, the second and third structural units may be present in an amount from about 5 mol% to about 45 mol% (e.g., 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%). The amounts included are within the ranges of 1%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, and 45 mol%, respectively; within the ranges of 5 mol% to 30 mol%, 5 mol% to 25 mol%, 5 mol% to 20 mol%, or 10 mol% to 20 mol%.

[0069] In 100 mol% (meth)acryloyl-based binders, the second structural unit may be present in an amount from about 0.1 mol% to about 45 mol% (e.g., 0.1 mol%, 0.5 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%). The amounts included are within the ranges of 1%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, and 45 mol%, respectively; within the ranges of 5 mol% to 45 mol%; within the ranges of 0.1 mol% to 30 mol%; within the ranges of 0.1 mol% to 20 mol%; within the ranges of 0.1 mol% to 10 mol%; or within the ranges of 1 mol% to 10 mol%.

[0070] In 100 mol% of (meth)acryloyl-based binders, the third structural unit may be included in an amount ranging from about 0 mol% to about 30 mol% (e.g., 0 mol%, 0.1 mol%, 0.5 mol%, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%), in the range of 1 mol% to 30 mol%, in the range of 1 mol% to 20 mol%, in the range of 1 mol% to 10 mol%, in the range of 5 mol% to 15 mol%, or in the range of 5 mol% to 20 mol%.

[0071] When the content of each structural unit is within the above range, the heat resistance and adhesive strength of the diaphragm can be further increased.

[0072] The first structural unit derived from (meth)acrylamide can be represented by the following chemical formula 1: Chemical Formula 1: .

[0073] In chemical formula 1, R 1 and R 2 Each is independently either hydrogen or methyl.

[0074] The second structural unit derived from (meth)acrylamidosulfonic acid or its salt may be or include structural units derived from (meth)acrylamidosulfonic acid or (meth)acrylamidosulfonate, and (meth)acrylamidosulfonate may be or include the conjugate base of (meth)acrylamidosulfonic acid, (meth)acrylamidosulfonate, or its derivatives. The structural unit derived from (meth)acrylamidosulfonic acid or (meth)acrylamidosulfonate may be represented, for example, by any one or more of the following chemical formulas 2, 3, 4, and combinations thereof: Chemical formula 2:

[0075] Chemical formula 3:

[0076] Chemical formula 4:

[0077] In chemical formulas 2 to 4, R 10 R 11 R 12 R 13 R 14 and R 15 Each is independently either hydrogen or methyl. L 1 L 2 and L 3 Each of these groups may independently be or include substituted or unsubstituted C1 to C10 alkylene groups, substituted or unsubstituted C3 to C20 cycloalkylene groups, substituted or unsubstituted C6 to C20 arylene groups, or substituted or unsubstituted C3 to C20 heterocyclic groups. a, b, and c can each be an integer in the range of 0 to 2. M can be or includes alkali metals, and Alkali metals may be or include at least one of, for example, lithium, sodium, potassium, rubidium or cesium.

[0078] As an example, in chemical formulas 2 to 4, L 1 L 2 and L 3 Each of them may be or include substituted or unsubstituted C1 to C10 alkylene groups, and a, b and c may each be equal to 1.

[0079] The structural units derived from (meth)acrylamide sulfonic acid or its salts may include one or more of the structural units represented by Chemical Formula 2, Chemical Formula 3, and Chemical Formula 4. As an example, the aforementioned structural units may include the structural units represented by Chemical Formula 2, and as another example, may include both structural units represented by Chemical Formula 2 and Chemical Formula 3.

[0080] When both structural units represented by chemical formula 2 and structural units represented by chemical formula 3 are included, the molar ratio of the structural unit represented by chemical formula 2 to the structural unit represented by chemical formula 3 may be in the range of about 10:1 to about 1:2, for example in the range of 5:1 to 1:1, or for example in the range of 3:1 to 1:1.

[0081] The sulfonic acid group in the structural unit derived from (meth)acrylamidosulfonic 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, sulfonyl alkyl (meth)acrylate, or its salt. 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 or include at least one of C1 to C20 alkyl groups, C1 to C10 alkyl groups, or C1 to C6 alkyl groups. The salt refers to a salt composed of the aforementioned sulfonic acid and a desired ion. The ion may be or include, for example, an alkali metal ion, and in this case, the salt may be or include an alkali metal sulfonic acid salt.

[0082] Acrylamidoalkyl sulfonic acid can be or includes, for example, 2-acrylamido-2-methylpropane sulfonic acid.

[0083] The third structural unit derived from (meth)acrylic acid or (meth)acrylate can be represented, for example, by any one or more of the following chemical formulas 5, 6, 7, and combinations thereof: Chemical formula 5:

[0084] Chemical Formula 6:

[0085] Chemical Formula 7: .

[0086] In chemical formulas 5 to 7 R 3 R 4 R 6 R 7 R 8 and R 9 Each is independently either hydrogen or methyl. R 5 It is or includes substituted or unsubstituted C1 to C20 alkyl groups, and M is or includes alkali metals.

[0087] 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, for example, derived from alkyl (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 be, for example, in the range of 1 to 20, for example, in the range of 1 to 10, for example, in the range of 1 to 5.

[0088] Examples of (meth)acrylate alkyl esters having one to five carbon atoms, wherein the alkyl or perfluoroalkyl group bonded to a non-carbonyl oxygen atom may include alkyl acrylates such as at least one of methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, or tert-butyl acrylate; 2-(perfluoroalkyl)ethyl acrylate, such as 2-(perfluorobutyl)ethyl acrylate or 2-(perfluoropentyl)ethyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and tert-butyl methacrylate; and 2-(perfluoroalkyl)ethyl methacrylate, such as 2-(perfluorobutyl)ethyl methacrylate or 2-(perfluoropentyl)ethyl methacrylate.

[0089] Examples of other (meth)acrylate alkyl esters may include: alkyl acrylates having 6 to 18 carbon atoms in an alkyl group bonded to a non-carbonyl oxygen atom, such as or including at least one of n-hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, or isobornyl acrylate; alkyl methacrylates having 6 to 18 carbon atoms in an alkyl group bonded to a non-carbonyl oxygen atom, such as or including at least one of n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecanyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, or cyclohexyl methacrylate; 2-(perfluoroalkyl)ethyl acrylate having 6 to 18 carbon atoms in a perfluoroalkyl group bonded to a non-carbonyl oxygen atom, such as or including 2-... At least one of the following: (perfluorohexyl)ethyl acrylate, 2-(perfluorooctyl)ethyl acrylate, 2-(perfluorocyano)ethyl acrylate, 2-(perfluorodecyl)ethyl acrylate, 2-(perfluorododecyl)ethyl acrylate, 2-(perfluorotetradecyl)ethyl acrylate, or 2-(perfluorohexadecyl)ethyl acrylate; and 2-(perfluoroalkyl)ethyl methacrylate having 6 to 18 carbon atoms in a perfluoroalkyl group bonded to a non-carbonyl oxygen atom, such as or including at least one of the following: 2-(perfluorohexyl)ethyl methacrylate, 2-(perfluorooctyl)ethyl methacrylate, 2-(perfluorononyl)ethyl methacrylate, 2-(perfluorodecyl)ethyl methacrylate, 2-(perfluorododecyl)ethyl methacrylate, 2-(perfluorotetradecyl)ethyl methacrylate, or 2-(perfluorohexadecyl)ethyl methacrylate.

[0090] The structural units derived from (meth)acrylic acid, (meth)acrylates or their salts may include one or all of the structural units represented by Formula 5, Formula 6 and Formula 7. When all are included, the structural units represented by Formula 5, Formula 6 and Formula 7 may be included in a molar ratio of about 10:1 to about 1:1, for example in the range of 6:1 to 1:1, for example in the range of 3:1 to 1:1.

[0091] (Meth)acryloyl adhesives can be represented, for example, by the following chemical formula 8: Chemical formula 8: .

[0092] In chemical formula 8, R 1 R 2 R 12 R 13 R 16 and R 17 Each is independently either hydrogen or methyl. R 18 Yes or includes OR or O - M + Wherein, R is or includes hydrogen or a C1 to C6 alkyl group, and M is an alkali metal. L 2 It includes, or comprises, substituted or unsubstituted C1 to C10 alkylene groups, substituted or unsubstituted C3 to C20 cycloalkylene groups, substituted or unsubstituted C6 to C20 arylene groups, or substituted or unsubstituted C3 to C20 heterocyclic groups. b is an integer in the range of 0 to 2. M is or includes alkali metals, and l, m, and n refer to the molar ratio of each unit.

[0093] Alkali metals may be or include at least one of, for example, lithium, sodium, potassium, rubidium or cesium.

[0094] As an example, in chemical formula 8, l + m + n = 1. Additionally, as an example, 0.05 ≤ (l + n) ≤ 0.45 and 0.55 ≤ m ≤ 0.95, for example, 0 ≤ l ≤ 0.4 and 0 ≤ n ≤ 0.1, for example, 0.8 ≤ m ≤ 0.9, 0 ≤ l ≤ 0.1 and 0 ≤ n ≤ 0.1, or for example, 0.8 ≤ m ≤ 0.9, 0.01 ≤ l ≤ 0.1 and 0.01 ≤ n ≤ 0.1.

[0095] As an example, in chemical formula 8, L 2 It may be or include substituted or unsubstituted C1 to C10 alkylene groups, and b may be equal to 1.

[0096] In (meth)acryloyl-based adhesives, relative to 100 mol% of the total (meth)acrylamide sulfonic acid structural units, the content is increased by alkali metals (M... + The substituted structural units may be present in amounts ranging from about 50 mol% to about 100 mol%, for example, from 60 mol% to 90 mol% or from 70 mol% to 90 mol%. When the above ranges are met, (meth)acryloyl binders and membranes including (meth)acryloyl binders may exhibit desired or improved adhesive strength, heat resistance, and oxidation resistance.

[0097] (Methacryl)acrylyl adhesives may also include other units besides those described above. For example, (meth)acrylyl adhesives may also include units derived from alkyl (meth)acrylates, units derived from diene adhesives, units derived from styrene adhesives, ester-containing units, carbonate-containing units, or combinations thereof.

[0098] (Methacrylamide) adhesives can take various forms, such as alternating polymers in which units are distributed alternately, random polymers in which units are distributed randomly, or grafted polymers in which some of the structural units are grafted.

[0099] The weight-average molecular weight of (meth)acryloyl-based adhesives can range from about 350,000 g / mol to about 970,000 g / mol, for example, from 450,000 g / mol to 970,000 g / mol or from 450,000 g / mol to 700,000 g / mol. When the weight-average molecular weight of (meth)acryloyl-based adhesives meets the above range, the (meth)acryloyl-based adhesives and the membranes including the (meth)acryloyl-based adhesives can exhibit desired or improved adhesive strength, heat resistance, and air permeability. The weight-average molecular weight can be the converted average molecular weight of polystyrene measured using gel permeation chromatography.

[0100] (Methacrylamide) binders can be prepared by various known methods, such as emulsion polymerization, suspension polymerization, bulk polymerization, or solution polymerization.

[0101] (Methacrylamide) adhesives can be prepared by solution polymerization.

[0102] According to one example embodiment, (meth)acryloyl-based adhesives may be included in the coating of a diaphragm in the form of a film.

[0103] (Methacryl)acryloyl binders may be included in amounts ranging from about 30 wt% to about 70 wt% (e.g., 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%), from 30 wt% to 60 wt%, or from 40 wt% to 60 wt% of the total amount of (meth)acryloyl binders, crosslinking agents, and carboxyalkyl cellulose or salts thereof. Within the above range, the heat resistance in the electrolyte can be improved.

[0104] Crosslinking agents may include one or more of aziridine crosslinking agents and carbodiimide crosslinking agents.

[0105] Aziridine and carbodiimide crosslinking agents can crosslink (meth)acryloyl binders and allow the diaphragm to easily meet the aforementioned dry shrinkage and electrolyte shrinkage ranges. For example, the crosslinking agent can be or includes aziridine crosslinking agents. Compared to carbodiimide crosslinking agents, aziridine crosslinking agents can further reduce the dry shrinkage and electrolyte shrinkage.

[0106] Aziridine crosslinking agents may be or include at least one of bifunctional or higher-functional aziridine crosslinking agents. Here, "bifunctional or higher-functional" means that there are two or more aziridine groups in the molecule. According to an example embodiment, aziridine crosslinking agents may be or include at least one of bifunctional or trifunctional aziridine crosslinking agents.

[0107] 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-aziridineyl)phosphine oxide, N,N-hexamethylene-bis(aziridinecarboxamide), trimethylolpropane tris(2-methyl-1-aziridine propionate), trimethylolpropane tris(β-N-aziridineyl)propionate, and pentaerythritol tris(3-(1-aziridineyl)propionate).

[0108] Carbodiimide crosslinking agents may include one or more of monocarbodiimide compounds and polycarbodiimide compounds.

[0109] According to one example embodiment, the carbodiimide crosslinking agent may be or includes a monocarbodiimide compound having the chemical formula RN=C=N-R' (where R and R' are each independently or include substituted or unsubstituted C1 to C5 alkyl or substituted or unsubstituted C5 to C10 cycloalkyl).

[0110] According to another example embodiment, the carbodiimide crosslinking agent may be or includes a polycarbodiimide compound prepared by subjecting a diisocyanate to a decarboxylation condensation reaction in the presence of a carbodiimide catalyst.

[0111] The diisocyanate included in the decarboxylation condensation reaction may include at least one of, for example, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylene diisocyanate.

[0112] Additionally, examples of carbodiimide catalysts that may be included in decarboxylation condensation reactions may include phosphine oxides, such as at least one of 1-phenyl-2-phosphine-1-oxide, 3-methyl-2-phosphine-1-oxide, 1-ethyl-3-methyl-2-phosphine-1-oxide, 1-ethyl-2-phosphine-1-oxide or a 3-phosphine isomer thereof.

[0113] One or more of the crosslinking agents (e.g., aziridine crosslinking agents and carbodiimide crosslinking agents) may be included in a desired amount relative to the binder (e.g., (meth)acryloyl binder and carboxyalkyl cellulose or its salts).

[0114] According to one example embodiment, the crosslinking agent may be included in an amount ranging from about 5 wt% to about 30 wt% (e.g., 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%), from 10 wt% to 30 wt%, or from 10 wt% to 20 wt% of the total amount of the (meth)acryloyl binder, the crosslinking agent, and carboxyalkyl cellulose or its salts. Within the above ranges, heat resistance in the electrolyte can be improved.

[0115] One or more of the crosslinking agents (e.g., aziridine crosslinking agents and carbodiimide crosslinking agents) may be included in a desired amount relative to the binder (e.g., (meth)acryloyl binder). For example, the crosslinking agent may be present in a range of about 5 wt% to about 50 wt% relative to the (meth)acryloyl binder (e.g., 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%). The amounts are included in the range of 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt%, 36wt%, 37wt%, 38wt%, 39wt%, 40wt%, 41wt%, 42wt%, 43wt%, 44wt%, 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, and 50wt%), for example, in the range of 10wt% to 50wt%, in the range of 20wt% to 50wt%, or in the range of 10wt% to 20wt%. Within the above ranges, heat resistance can be increased.

[0116] Carboxyalkyl cellulose or its salts can react with crosslinking agents by having a cyclic structure in the molecule and a carboxyl group in the molecule, thereby increasing the modulus of the coating and further reducing the dry shrinkage and shrinkage in the electrolyte.

[0117] Carboxyalkyl cellulose can be or includes, for example, carboxymethyl cellulose.

[0118] Salts of carboxyalkyl cellulose are salts of carboxyalkyl cellulose and may be or include, for example, monovalent metal salts of carboxyalkyl cellulose, such as sodium salts of carboxyalkyl cellulose.

[0119] Carboxyalkyl cellulose or its salts may be included in desired amounts, relative to binders (e.g., (meth)acryloyl-based binders) and crosslinking agents.

[0120] According to one example embodiment, carboxyalkyl cellulose or its salt may be present in an amount ranging from 20 wt% to 70 wt% of the total amount of (meth)acryloyl binder, crosslinking agent, and carboxyalkyl cellulose or its salt (e.g., 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%). The amounts include those ranging from 48wt%, 49wt%, 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, and 70wt%), from 20wt% to 65wt%, from 20wt% to 60wt%, from 30wt% to 70wt%, from 30wt% to 60wt%, or from 40wt% to 60wt%. Within the above ranges, the heat resistance in the electrolyte can be improved.

[0121] The filler may include fillers with a particle size D100 of about 1.0 μm or smaller. Within the above range, when the filler is combined with (meth)acryloyl binders, crosslinking agents, and carboxyalkyl cellulose or salts thereof, the dry shrinkage rate and the shrinkage rate in the electrolyte can be readily met. For example, the particle size D100 of the filler can be 1.0 μm or smaller (e.g., 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, 0.7 μm, 0.75 μm, 0.8 μm, 0.85 μm, 0.9 μm, 0.95 μm, 1.0 μm), 0.8 μm or smaller, 0.7 μm or smaller, in the range of 0.1 μm to 0.8 μm, in the range of 0.1 μm to 0.7 μm, or in the range of 0.5 μm to 0.8 μm.

[0122] According to one example embodiment, the particle size D50 of the filler can be about 0.4 μm or smaller (e.g., 0.05 μm, 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm), 0.35 μm or smaller, 0.3 μm or smaller, or in the range of 0.1 μm to 0.3 μm. Within the above range, heat resistance can be improved.

[0123] According to one example embodiment, fillers with a particle size D100 of about 1.0 μm or smaller may be included in an amount of about 95 wt% or greater of the total filler in the coating, for example, an amount in the range of 95 wt% to 100 wt%, an amount in the range of 98 wt% to 100 wt%, or an amount of 100 wt%. Within the above ranges, the effect of a diaphragm can be easily achieved.

[0124] According to one example embodiment, the filler may or may not be surface modified.

[0125] Surface modification can include modifying the surface of the filler to have an amino group. Here, "amino" can refer to... N(R 1 (R) 2 (Here, R) 1 and R 2 Each is or includes hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, and for example, refers to an -NH2 group. Such surface modification can broaden the particle size range of the filler required to provide the dry shrinkage and shrinkage in the electrolyte compared to the use of unmodified fillers.

[0126] According to one example embodiment, surface modification may include surface treatment of unmodified fillers with an aminosilane compound. The aminosilane compound may include a silane compound having one or more nitrogen atoms (e.g., 1 to 6 nitrogen atoms).

[0127] In one example embodiment, the aminosilane compound may include, but is not limited to, one or more compounds represented by the following chemical formulas 9, 10 and 11: Chemical formula 9:

[0128] Chemical Formula 10:

[0129] Chemical Formula 11: .

[0130] In chemical formulas 9 to 11, X 1 X2 and X 3 Each of these elements independently comprises or includes hydrogen, hydroxyl, substituted or unsubstituted C1 to C20 alkyl, substituted or unsubstituted C6 to C20 aryl, substituted or unsubstituted C3 to C20 cycloalkyl, substituted or unsubstituted C7 to C20 arylalkyl, substituted or unsubstituted C1 to C20 alkoxy, or substituted or unsubstituted C6 to C20 aryloxy. X 1 X 2 and X 3 At least one of them is or includes a hydroxyl group, a substituted or unsubstituted C1 to C20 alkoxy group, or a substituted or unsubstituted C6 to C20 aryloxy group. Y 1 Y 2 Y 3 Y 4 Y 5 and Y 6 Each is independently or includes a divalent C1 to C20 aliphatic hydrocarbon group, a divalent C5 to C20 alicyclic hydrocarbon group, or a divalent C6 to C20 aromatic hydrocarbon group, and R 15 R 16 R 17 R 18 R 19 R 20 R 21 R 22 and R 23 Each is independently or includes hydrogen, hydroxyl, a substituted or unsubstituted monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0131] For example, aminosilane compounds may include one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, aminoethylaminopropyltrimethoxysilane, aminoethylaminopropyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane, aminoethylaminomethyltriethoxysilane, aminoethylaminomethyldiethoxysilane, diethyltriaminopropyltrimethoxysilane, diethyltriaminopropyltriethoxysilane, diethyltriaminopropylmethyldimethoxysilane, or diethyltriaminomethyldiethoxysilane, but are not limited thereto.

[0132] According to one example embodiment, surface modification can be carried out using typical methods employing aminosilane compounds.

[0133] 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 increase heat resistance. Inorganic fillers may include, for example, at least one of metal oxides, quasi-metal oxides, metal fluorides, metal hydroxides, or combinations thereof. Inorganic fillers may include, for example, at least one of Al₂O₃, SiO₂, TiO₂, SnO₂, CeO₂, MgO, NiO, CaO, GaO, ZnO, ZrO₂, Y₂O₃, SrTiO₃, BaTiO₃, Mg(OH)₂, boehmite, or combinations thereof, but are not limited thereto. Organic fillers may include, but are not limited to, at least one of acrylic compounds, imide compounds, amide compounds, or combinations thereof. Organic fillers may have a core-shell structure, but are not limited thereto. For example, the filler may be boehmite.

[0134] The filler can be approximately spherical, approximately plate-shaped, approximately cubic, or amorphous. For example, the filler can be cubic, and the cubic shape can significantly reduce shrinkage.

[0135] The filler may be included in a desired amount relative to the binder (e.g., a (meth)acryloyl binder). According to one example embodiment, the (meth)acryloyl binder and filler may be in a ratio of 1:10 to 1:50 (e.g., 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:25, 1:26, 1:27, 1:50). The mass ratios range from 1:28, 1:29, 1:30, 1:31, 1:32, 1:33, 1:34, 1:35, 1:36, 1:37, 1:38, 1:39, 1:40, 1:41, 1:42, 1:43, 1:44, 1:45, 1:46, 1:47, 1:48, 1:49, and 1:50, for example, mass ratios from 1:20 to 1:30. Within the above ranges, the heat resistance in the electrolyte can be improved.

[0136] The filler may be included in an amount ranging from about 50 wt% to about 99 wt% of the total coating amount, for example, in the range of 70 wt% to 99 wt%, for example, in the range of 75 wt% to 99 wt%, for example, in the range of 80 wt% to 99 wt%, for example, in the range of 85 wt% to 99 wt%, for example, in the range of 90 wt% to 99 wt%, or for example, in the range of 95 wt% to 99 wt%. When the filler is included within the above ranges, the diaphragm may exhibit desired or improved heat resistance, durability, oxidation resistance, and stability.

[0137] Each coating may have a thickness in the range of about 0.01 μm to about 20 μm, and within the above range, it may have a thickness in the range of 1 μm to 10 μm, in the range of 1 μm to 5 μm, or in the range of 1 μm to 3 μm.

[0138] The ratio of coating thickness to the thickness of the porous substrate can range from about 0.05 to about 0.5, for example, from 0.05 to 0.4, from 0.05 to 0.3, or from 0.1 to 0.2. Within these ranges, the diaphragm can exhibit desired or improved permeability, heat resistance, adhesive strength, etc. Here, when the coating is formed on only one surface of the porous substrate, "coating thickness" refers to the thickness of one coating, and when the coating is formed on both surfaces of the porous substrate, "coating thickness" refers to the thickness of both coatings.

[0139] Porous substrate Porous substrates can be or include substrates having multiple pores and generally included in electrochemical devices. Porous substrates can be or include polymer membranes formed from or comprising any polymer, such as or including at least one of polyolefins (e.g., polyethylene or polypropylene), polyesters (e.g., polyethylene terephthalate or polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetheretherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon (polytetrafluoroethylene), or copolymers or mixtures of two or more types thereof.

[0140] The porous substrate can be or includes, for example, a polyolefin substrate comprising polyolefins, and the polyolefin substrate can have desired or improved shut-off functionality, thereby contributing to increased battery safety. The polyolefin substrate can be or includes at least one of, for example, a polyethylene monolayer, a polypropylene monolayer, a polyethylene / polypropylene bilayer, a polypropylene / polyethylene / polypropylene trilayer, and a polyethylene / polypropylene / polyethylene trilayer. For example, the polyolefin resin can include non-olefin resins other than olefin resins or copolymers comprising olefin and non-olefin monomers.

[0141] The porous substrate can have a thickness in the range of about 1 μm to about 40 μm, for example, in the range of 1 μm to 30 μm, in the range of 1 μm to 20 μm, or in the range of 5 μm to 15 μm.

[0142] A separator for a rechargeable lithium battery according to an example embodiment may have desired or improved adhesive strength. For example, the adhesive strength of the separator for a rechargeable lithium battery may be about 0.05 gf / mm or greater, for example, in the range of 0.05 gf / mm to 0.1 gf / mm, or for example, in the range of 0.05 gf / mm to 0.2 gf / mm. Adhesive strength can be measured by the following methods.

[0143] A separator for a rechargeable lithium battery was positioned between the positive and negative electrodes and bonded to them by passing it between rollers at a speed of 150 mm / sec and a pressure of 250 kgf in an 80°C chamber. Samples were prepared by cutting the separator bonded to the positive and negative electrodes into pieces 25 mm wide and 50 mm long. A universal testing machine (UTM) was used as the bonding strength measuring device. In the above samples, the separator was separated from the negative electrode plate by approximately 10 mm to 20 mm. The separator was then fixed to the upper clamp, and the negative electrode plate to the lower clamp, with a gap of 20 mm between the clamps. Peeling was then performed by pulling in a 180° direction. After starting peeling at a peeling speed of 20 mm / min, the force required to peel 40 mm was measured three times to obtain the average value. The average value was calculated as the average of the measured values.

[0144] A separator for a rechargeable lithium battery according to an example embodiment can exhibit desired or improved air permeability, and for example, an air permeability value of less than about 200 sec / 100 cc, such as 190 sec / 100 cc or less, or 180 sec / 100 cc or less. That is, the air permeability value per unit thickness of the separator can be less than 40 sec / 100 cc 1 μm, such as 30 sec / 100 cc 1 μm or less, or 25 sec / 100 cc 1 μm or less. Here, air permeability refers to the time (in seconds) required for 100 cc of air to pass through a unit thickness of the separator. Air permeability per unit thickness can be obtained by measuring the air permeability of the total thickness of the separator and dividing that air permeability by the thickness. Air permeability can be obtained by measuring the time required for 100 cc of air to pass through the separator using an air permeability measuring device (EG01-55-1MR, Asahi Seiko Ltd.).

[0145] A separator for a rechargeable lithium battery according to an example embodiment can be formed by applying a composition for forming a coating to one or both surfaces of a porous substrate, allowing it to dry, and then curing the composition on the porous substrate. Curing can be performed using, for example, typical methods known to those skilled in the art.

[0146] Figure 1This is a cross-sectional view showing 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 coatings 2 on two surfaces of the porous substrate 1. The coating 2 may include filler 3, a crosslinking product 4 of a (meth)acryloyl binder and a crosslinking agent, and carboxyl cellulose or a salt thereof (not shown).

[0147] Rechargeable lithium batteries According to one example embodiment, a rechargeable lithium battery includes a separator, a positive electrode, and a negative electrode for the rechargeable lithium battery.

[0148] 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.

[0149] positive electrode The positive electrode for a rechargeable lithium 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 a positive electrode active material and may further include a binder and / or a conductive material.

[0150] For example, the positive electrode may also include additives that can be configured to sacrifice the positive electrode.

[0151] Positive electrode active material The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, it may include 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.

[0152] 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.

[0153] As an example, it may include the following compounds represented by any of the following chemical formulas. 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 Ni1-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).

[0154] In the above chemical formula, A is or includes at least one of Ni, Co, Mn, or a combination thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D is or includes at least one of O, F, S, P, or a combination thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L 1 It is or includes at least one of Mn, Al, or combinations thereof.

[0155] 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 composite oxide, the nickel content of the high-nickel positive electrode active material is 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 applied to high-capacity, high-density rechargeable lithium batteries.

[0156] 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%.

[0157] The binder is configured to adhere the positive electrode active material particles to each other and is also configured to adhere the positive electrode active material to the current collector. As a non-limiting example, examples of the binder 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.

[0158] Conductive materials may be included to impart conductivity (e.g., electrical conductivity) to the 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 may be included in the battery. 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., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0159] Al can be included as a current collector, but is not limited to it.

[0160] negative electrode The negative electrode for a rechargeable lithium battery may include a current collector and a layer of negative electrode active material on the current collector. The negative electrode active material layer may include a negative electrode active material and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0161] For example, the negative electrode active material layer may include from about 90 wt% to about 99 wt% of a negative electrode active material, from about 0.5 wt% to about 5 wt% of a binder, and from about 0 wt% to about 5 wt% of a conductive material.

[0162] Negative electrode active material The negative electrode active material may include at least one of a material capable of reversibly inserting / extracting lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0163] The material capable of reversibly inserting / extracting lithium ions may include a carbon-based negative electrode active material, such as, for example, crystalline carbon, amorphous carbon, or a combination thereof. Crystalline carbon may be or include graphite, such as natural graphite or artificial graphite that is amorphous, substantially flaky, substantially lamellar, substantially spherical, or fibrous. Amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, and the like.

[0164] 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.

[0165] The material capable of doping / dedoping lithium may be or include at least one of 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 combinations thereof). The Sn-based negative electrode active material may include at least one of Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0166] The silicon-carbon composite may be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are assembled and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be between the primary silicon particles. For example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0167] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0168] Si-based or Sn-based negative electrode active materials can be combined with carbon-based negative electrode active materials.

[0169] The binder can be configured to adhere the negative electrode active material particles to each other, and is also configured to adhere the negative electrode active material to the current collector. The binder may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0170] 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.

[0171] 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.

[0172] When an aqueous binder is included as the negative electrode binder, a cellulose compound capable of imparting viscosity may be further included. 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.

[0173] Dry adhesives can be or include polymeric materials that can be fibrous. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0174] Conductive materials may be included to impart conductivity (e.g., electrical conductivity) to the 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 may be included in the 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., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0175] 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.

[0176] Rechargeable lithium batteries may also include an electrolyte.

[0177] electrolyte Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0178] Non-aqueous organic solvents can be configured as media for transporting ions that participate in the electrochemical reactions of a battery.

[0179] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents or alcohol solvents, aprotic solvents or combinations thereof.

[0180] 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).

[0181] 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.

[0182] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 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 at least one of the following compounds: 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.

[0183] Non-aqueous organic solvents may be included alone or in combination of two or more solvents.

[0184] In addition, 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 of about 1:1 to about 1:9.

[0185] Lithium salts dissolved in organic solvents are configured to supply lithium ions in batteries, enabling basic operation of rechargeable lithium batteries 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 At least one of the following: (SO2) (where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0186] Rechargeable lithium batteries can be classified according to their shape as cylindrical batteries, prismatic batteries, pouch batteries, or coin-shaped batteries, etc.

[0187] Figures 2 to 5 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown. Figure 4 and Figure 5 A pouch-type battery is shown. (See reference) Figures 2 to 5 The rechargeable lithium battery 100 may include an electrode assembly 40 comprising a separator 30 between a positive electrode 10 and a negative electrode 20, and a housing 50 therein housing the electrode assembly 40. The positive electrode 10, negative electrode 20, and separator 30 may be impregnated with an electrolyte (not shown). The rechargeable lithium battery 100 may include a sealing member 60 for sealing the housing 50, such as... Figure 2 As shown. In Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include Figure 5 The electrode terminal 70 shown, or for example Figure 4 The positive electrode terminal 71 and negative electrode terminal 72 shown form an electrical path for leading the current generated in the electrode assembly 40 to the outside of the battery 100.

[0188] 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 electrical devices.

[0189] Examples and comparative examples of this disclosure are described below. However, the following examples are merely exemplary embodiments of the invention, and this disclosure is not limited to these examples.

[0190] Preparation Example 1 In a 10L four-necked flask equipped with a stirrer, thermometer, and cooling tube, distilled water (6361g), acrylic acid (1.0mol), acrylamide (8.5mol), potassium persulfate (0.01mol), 2-acrylamido-2-methylpropanesulfonic acid (0.5mol), and a 5N lithium hydroxide aqueous solution (1.05 equivalents relative to the total amount of 2-acrylamido-2-methylpropanesulfonic acid) were added. The process was then repeated three times to reduce the internal pressure to 10mmHg using a diaphragm pump and to restore the internal pressure to atmospheric pressure using nitrogen.

[0191] The reaction was carried out for 12 hours, while the temperature of the reaction solution was maintained between 65°C and 70°C. After cooling to room temperature, the pH of the reaction solution was adjusted to 7 to 8 using a 25% ammonia solution.

[0192] Therefore, 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. The non-volatile component in approximately 10 mL of the reaction solution (reaction product) was measured, and the result was 9.5 wt% (theoretical value: 10 wt%).

[0193] Preparation Example 2 Acryloyl-based adhesives were prepared in the same manner as in Preparation Example 1, except that acrylic acid and acrylamide were used instead of 2-acrylamido-2-methylpropanesulfonic acid. The molar ratio of acrylic acid + lithium acrylate and acrylonitrile was 42:58. The non-volatile component of the reaction solution was 9.0 wt% (theoretical value: 10 wt%).

[0194] Preparation Example 3 Acryloyl-based adhesives were prepared in the same manner as in Preparation Example 1, except that acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid were used instead of acrylamide. The molar ratio of acrylic acid + lithium acrylate and 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%).

[0195] Preparation Example 4 Acryloyl-based 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%).

[0196] Example 1 A dispersion was prepared by mixing the acryloyl binder (10 wt% in distilled water) prepared in Preparation Example 1 with boehmite (particle size D100: 0.5 μm, particle size D50: 0.2 μm, cubic shape) as filler at a mass ratio of acryloyl binder: filler = 1:30 (based on solid content), adding the mixture to an aqueous solvent, and then grinding and dispersing the mixture at 25 °C for 30 minutes using a bead mill to prepare the dispersion.

[0197] A composition for forming a coating was prepared by adding trimethylolpropane tris(2-methyl-1-aziridine propionate) (a trifunctional aziridine crosslinking agent) and carboxyalkyl cellulose (CMC) as a aziridine crosslinking agent to a dispersion and adding water to make the total solid content 20 wt%. In this case, the ratio of acryloyl binder:carboxyalkyl cellulose:aziridine crosslinking agent was 45:45:10 (parts by weight) out of a total of 100 parts by weight.

[0198] A separator for rechargeable lithium batteries was manufactured by coating two surfaces of a polyethylene film (thickness: 8 μm, SK Corporation, air permeability: 120 sec / 100 cc, puncture strength: 480 kgf) serving as a porous substrate with a composition for forming the coating using a molding method, and then drying and aging the composition on the porous substrate in an oven at 80°C for 16 hours.

[0199] Examples 2 to 8 The separator for rechargeable lithium batteries is manufactured in the same manner as in Example 1, except that: in Example 1, as shown in Table 1 below, boehmite (cubic) is used as the filler, but D50 and D100 are changed, the mass ratio of acryloyl binder to filler is changed, and the contents of acryloyl binder, carboxyalkyl cellulose and aziridine crosslinker are changed.

[0200] Example 9 The separator for rechargeable lithium batteries is manufactured in the same manner as in Example 1, except that a carbodiimide crosslinking agent CARBODILITE V-05 (Nisshinbo Chemical) is used instead of an aziridine crosslinking agent.

[0201] Example 10 The separator for the rechargeable lithium battery is manufactured in the same manner as in Example 1, except that in Example 1, boehmite (particle size D100: 0.5 μm, particle size D50: 0.2 μm, plate-shaped) is used.

[0202] Example 11 Boehmite (D100: 0.5 μm, D50: 0.2 μm) surface-modified with 3-aminopropyltrimethoxysilane was prepared by adding 3-aminopropyltrimethoxysilane (particle size D100: 0.5 μm, particle size D50: 0.2 μm, cubic) of boehmite corresponding to 0.05 mmol per solids content to anhydrous toluene and refluxing at 80 °C. The surface-modified boehmite has amino groups (-NH2) on its outermost surface.

[0203] The prepared surface-modified boehmite was used to manufacture a separator for a rechargeable lithium battery in the same manner as in Example 1.

[0204] Examples 12 to 17 The separator for rechargeable lithium batteries was manufactured in the same manner as in Example 11, except that: in Example 1, as shown in Table 2 below, modified boehmite (cubic) was used as the filler, but D50 and D100 were changed, the mass ratio of acryloyl binder to filler was changed, and the contents of acryloyl binder, carboxyalkyl cellulose and aziridine crosslinker were changed.

[0205] Comparison Examples 1 to 8 The separator for rechargeable lithium batteries is manufactured in the same manner as in Example 1, except that: in Example 1, as shown in Table 1 below, boehmite (cubic) is used as the filler, but D50 and D100 are changed, the mass ratio of acryloyl binder to filler is changed, and the contents of acryloyl binder, carboxyalkyl cellulose and aziridine crosslinker are changed.

[0206] PVA is a homopolymer of polyvinyl alcohol.

[0207] The epoxy crosslinking agent is ethylene glycol diglycidyl ether.

[0208] PVDF stands for polyvinylidene fluoride.

[0209] SBR stands for styrene-butadiene rubber.

[0210] Dry shrinkage rate (unit: %) 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 the sample, and the sample was placed between pieces of paper or alumina powder. The sample was then placed in an oven at 150°C for 1 hour. After removing the sample, the side length of the drawn square was measured, and the shrinkage rate in each of the longitudinal (MD) and transverse (TD) directions was calculated. The shrinkage rate was calculated according to Equation 1 below.

[0211] Equation 1: Shrinkage rate = (L0-L1) / L0×100%.

[0212] L0 represents the initial length of the diaphragm, and L1 represents the length of the diaphragm after standing at 150°C for 1 hour.

[0213] Shrinkage rate in electrolyte (unit: %) Samples were fabricated by cutting the separators for rechargeable lithium batteries of the example and comparative examples into 8cm x 8cm dimensions. A 5cm x 5cm square was drawn on the surface of the sample.

[0214] A slurry of positive electrode active material was prepared by mixing 97 wt% LiCoNiAl as the positive electrode active material, 1.5 wt% carbon nanotubes and 1.5 wt% polyvinyl fluoride as the conductive material and adding water.

[0215] A positive electrode is manufactured by applying a prepared positive electrode active material slurry onto an aluminum foil, and then drying and rolling the prepared positive electrode active material slurry and the aluminum foil.

[0216] 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 agent. A silicon-based negative electrode active material was used as the negative electrode active material. The negative electrode was manufactured by coating the prepared negative electrode active material slurry onto a copper foil and then drying and rolling the slurry and copper foil.

[0217] A sample was positioned between the positive and negative electrodes to form three positive electrode-sample-negative electrode laminates, which were then placed in a bag. 2g of electrolyte (1.5M LiPF6 dissolved in ethylene carbonate, methyl ethyl carbonate, and dimethyl carbonate (volume ratio 30:50:20)) was injected to completely saturate the laminate, which was then sealed and allowed to stand at 25°C for 12 hours. The laminate was then dried in an oven at 150°C for 1 hour, the sample was removed, and the side length of the drawn square was measured to calculate the shrinkage rate in each direction of MD and TD. The shrinkage rate was calculated according to Equation 1.

[0218] Table 1:

[0219] Table 2:

[0220] As shown in Tables 1 and 2, the example separators for rechargeable lithium batteries exhibit significantly low dry shrinkage and electrolyte shrinkage, thereby increasing battery stability.

[0221] Therefore, the separator for a rechargeable lithium battery according to an example embodiment of the present disclosure can exhibit significantly low dry shrinkage and electrolyte shrinkage, thereby increasing battery stability.

[0222] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and modifications may be made in any form within the scope of the claims, the detailed description of the invention, and the drawings, and it is self-evident that such modifications also fall within the scope of the invention.

Claims

1. A separator for a rechargeable lithium battery, the separator comprising: Porous substrate; as well as A coating is applied to at least one surface of the porous substrate. The coating comprises an adhesive, a crosslinking agent, a crosslinking product of carboxyalkyl cellulose or its salt, and a filler. The adhesive comprises a (meth)acrylamide-based adhesive containing a first structural unit derived from (meth)acrylamide and a second structural unit derived from (meth)acrylamide sulfonic acid or a salt thereof, and The crosslinking agent includes one or more of aziridine crosslinking agents and carbodiimide crosslinking agents.

2. The diaphragm according to claim 1, wherein, The coating comprises a composition containing the (meth)acryloyl-based 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 carboxyalkyl cellulose or its salt is included in an amount ranging from 20 wt% to 70 wt% of the total amount of the (meth)acryloyl adhesive, 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 carbodiimide crosslinking agent includes one or more of monocarbodiimide compounds and polycarbodiimide compounds.

7. The diaphragm according to claim 1, wherein, The particle size D100 of the filler is 1.0 μm or smaller.

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

9. The diaphragm according to claim 1, wherein, The filler is surface modified to have amino groups on its surface.

10. The diaphragm according to claim 1, wherein, The mass ratio of the (meth)acryloyl-based binder to the filler is in the range of 1:10 to 1:

50.

11. The diaphragm according to claim 1, wherein, Relative to the total amount of the (meth)acryloyl adhesive, the crosslinking agent, and the carboxyl cellulose or its salt: The (meth)acryloyl-based adhesive comprises, in an amount ranging from 30 wt% to 70 wt%, The crosslinking agent is included in an amount ranging from 5 wt% to 30 wt%, and The carboxyalkyl cellulose or its salts are included in an amount ranging from 20 wt% to 65 wt%.

12. The diaphragm according to claim 1, wherein, The first structural unit is represented by the following chemical formula 1: Chemical Formula 1: ， In chemical formula 1, R 1 and R 2 Each independently includes either hydrogen or methyl. The second structural unit is represented by any one or more of chemical formulas 2, 3, and 4: Chemical formula 2: Chemical formula 3: Chemical formula 4: ， 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 includes substituted or unsubstituted C1 to C10 alkylene groups, substituted or unsubstituted C3 to C20 cycloalkylene groups, substituted or unsubstituted C6 to C20 arylene groups, or substituted or unsubstituted C3 to C20 heterocyclic groups. a, b, and c are each an independent integer in the range of 0 to 2, and M includes alkali metals.

13. The diaphragm according to claim 1, wherein, The (meth)acryloyl-based adhesives also include a third structural unit derived from (meth)acrylic acid or (meth)acrylate.

14. The diaphragm according to claim 13, wherein, The third structural unit is represented by any one or more of chemical formulas 5, 6, and 7: Chemical formula 5: Chemical Formula 6: Chemical Formula 7: ， 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.

15. The diaphragm according to claim 1, wherein, The coating has a thickness ranging from 0.01 μm to 20 μm.

16. 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 15, between the positive electrode and the negative electrode.

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