Separator for rechargeable battery and rechargeable battery including the same

Abstract

The present disclosure relates to a separator for a rechargeable battery and a rechargeable battery including the same. The separator includes a porous substrate, a first coating layer on a first surface of the porous substrate, and a second coating layer on a second surface of the porous substrate. The first coating layer includes a crosslinking product of a binder and a crosslinking agent, a filler, and an adhesive binder. The second coating layer includes a crosslinking product of a binder and a crosslinking agent, a filler, and an adhesive binder. The binder in the first coating layer and the binder in the second coating layer each comprise a (meth) acrylic binder. The (meth) acrylic binder includes a first structural unit derived from (meth) acrylic acid, a (meth) acrylate, or a salt thereof, a second structural unit derived from a hydroxyalkyl (meth) acrylate, and a third structural unit derived from a (meth) acrylamidosulfonic acid or a salt thereof.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0163677, filed on November 16, 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 battery and a rechargeable battery including the separator. Background Technology

[0003] With the increasing use 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 includes a positive electrode and a negative electrode containing active materials capable of inserting and deintercalating lithium ions, and generates electrical energy through oxidation and reduction reactions as lithium ions are deintercalated / intercalated from the positive electrode into the negative electrode and from the negative electrode into the positive electrode.

[0005] A rechargeable lithium battery may include a separator between the positive and negative electrodes. The separator is impregnated with an electrolyte and is bonded to either the positive or negative electrode. Summary of the Invention

[0006] One example embodiment includes a separator for a rechargeable battery that provides low thermal shrinkage, low film resistance, high adhesion to electrode plates, and high rate performance during charging and discharging.

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

[0008] One example embodiment includes a separator for a rechargeable battery.

[0009] The separator for a rechargeable battery includes a porous substrate, a first coating layer on a first surface of the porous substrate, and a second coating layer on a second surface of the porous substrate.

[0010] The first coating layer includes a crosslinking product of the adhesive and crosslinking agent, fillers, and an adhesive adhesive. The second coating layer includes a crosslinking product of the adhesive and crosslinking agent, fillers, and an adhesive adhesive.

[0011] The binder in both the first and second coating layers comprises a (meth)acrylic acid binder. The (meth)acrylic acid binder includes a first structural unit derived from (meth)acrylic acid, (meth)acrylate, or a salt thereof; a second structural unit derived from a hydroxyalkyl methacrylate; and a third structural unit derived from (meth)acrylamidosulfonic acid or a salt thereof. The crosslinking agent includes an aziridine crosslinking agent. The filler comprises a mixture of a first filler and a second filler, wherein the first filler is an inorganic filler, and the second filler has a metal-organic framework structure. The adhesive binder in the first coating layer is a (meth)acrylic acid adhesive binder. The adhesive binder in the second coating layer is a fluorinated adhesive binder with a carbonyl group (C=O).

[0012] Another example embodiment includes a rechargeable battery.

[0013] A rechargeable battery includes a positive electrode, a negative electrode, and the aforementioned separator for a rechargeable battery located between the positive and negative electrodes. Attached Figure Description

[0014] 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: Figure 1 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment; and Figures 2 to 5 This is a schematic cross-sectional view of a rechargeable lithium battery according to an example embodiment. Detailed Implementation

[0015] Hereinafter, exemplary embodiments of the present disclosure are described in detail. However, these embodiments are given by way of example, and the present disclosure is not limited thereto, and is limited only by the scope of the appended claims.

[0016] 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 there are other components between them.

[0017] 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".

[0018] In this specification, “these (or their) combinations” may mean a mixture, stack, complex, copolymer, alloy, blend or reaction product of the components.

[0019] Unless otherwise defined herein, “particle size D50” can refer to the size of particles that constitute 50% 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 D50 from it. Optionally, particle size distribution can be measured using laser diffraction. When measuring particle size distribution by laser diffraction, for example, the particle size D50 can be calculated based on 50% 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 radiating ultrasound at an output of 60 W at approximately 28 kHz.

[0020] If the particles are spherical (when the particles are spherical), then particle size can refer to the diameter of the particles.

[0021] In this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0022] In the following text, unless otherwise defined, “substitution” means that the hydrogen in a compound is substituted with a substituent (such as 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') (where R and R' are both independently hydrogen or C1 to C6 alkyl), sulfobetaine (-RR'N) + (CH2) n SO3 - (n is a natural number from 1 to 10), carboxybenzene base (-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).

[0023] In the following text, C1 to C3 alkyl groups may be or include methyl, ethyl, or propyl. C1 to C10 alkylene groups may be or include, for example, C1 to C6 alkylene groups, C1 to C5 alkylene groups, or C1 to C3 alkylene groups, and may be or include, for example, methylene, ethylene, or propylene. C3 to C20 cycloalkylene groups may be or include, for example, C3 to C10 cycloalkylene groups or C5 to C10 cycloalkylene groups (e.g., cyclohexylene). C6 to C20 arylene groups may be or include, for example, C6 to C10 arylene groups (e.g., phenylene). C3 to C20 divalent heterocyclic groups may be or include, for example, C3 to C10 divalent heterocyclic groups (e.g., pyridylene).

[0024] In the following text, “heterogeneous” means including one or more heteroatoms (such as at least one of N, O, S, Si and P).

[0025] Additionally, in chemical formulas, the symbol * indicates a part that is attached to the same or different atoms, groups, or structural units.

[0026] 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) and which can exist in either a cation or a neutral state.

[0027] In this specification, when describing a range of values, “X to Y” means “X or greater and Y or less (X ≤ and ≤ Y)”.

[0028] 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 it, such as increments of 0.1%.

[0029] The following describes in detail the separator for a rechargeable battery and the rechargeable battery including the separator.

[0030] In the following description, only rechargeable lithium batteries are described. However, in addition to rechargeable lithium batteries, this disclosure can also be applied to rechargeable batteries with different metal ions.

[0031] According to one example embodiment, a separator for a rechargeable lithium-ion battery includes a porous substrate, a first coating layer on a first surface of the porous substrate, and a second coating layer on a second surface of the porous substrate. The first coating layer includes a crosslinking product of an adhesive and a crosslinking agent, a filler, and an adhesive binder. The second coating layer includes a crosslinking product of an adhesive and a crosslinking agent, a filler, and an adhesive binder. Both the adhesive in the first and second coating layers include a (meth)acrylic acid adhesive, which includes a first structural unit derived from (meth)acrylic acid, (meth)acrylate, or a salt thereof, a second structural unit derived from a hydroxyalkyl ester of (meth)acrylic acid, and a third structural unit derived from (meth)acrylamidosulfonic acid or a salt thereof. The crosslinking agent includes an aziridine crosslinking agent. The filler includes a mixture of a first filler and a second filler, wherein the first filler is an inorganic filler and the second filler is a metal-organic framework (MOF) structure. The adhesive binder in the first coating layer is a (meth)acrylic acid adhesive binder, and the adhesive binder in the second coating layer is a fluorinated adhesive binder having a carbonyl group (C=O).

[0032] According to one example embodiment, the first coating layer may be positioned close to the negative electrode of the battery, and the second coating layer may be positioned close to the positive electrode of the battery.

[0033] According to one example embodiment, the crosslinking product may be or include a thermally crosslinked product.

[0034] According to one example embodiment, the first coating layer may be formed of a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and a (meth)acrylic adhesive, or a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and a (meth)acrylic adhesive. According to one example embodiment, the second coating layer may be formed of a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and a carbonyl-based fluorinated adhesive, or a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and a carbonyl-based fluorinated adhesive.

[0035] The diaphragm can provide low thermal shrinkage, high rate capability during charging and discharging, low membrane resistance, and high adhesion to the electrode plates.

[0036] In one example embodiment, the diaphragm may have a dry heat shrinkage rate of about 12% or less in the longitudinal direction (machine orientation, MD) and about 5% or less in the transverse direction (TD), and a membrane resistance of about 0.5 Ω or less. MD and TD are substantially the same orientation as the MD and TD of the porous substrate, respectively.

[0037] In one example embodiment, the diaphragm may have an adhesion of about 1.1 gf / mm or greater to the positive electrode and an adhesion of about 0.85 gf / mm or greater to the negative electrode.

[0038] A first coating layer comprising fillers (i.e., a mixture of a first filler and a second filler) may be insufficient to provide a diaphragm with the aforementioned dry heat shrinkage range. A diaphragm having a first coating layer and a second coating layer comprising fillers and a crosslinked product comprising a (meth)acrylic acid binder and an aziridine crosslinking agent can satisfy the aforementioned dry heat shrinkage range and the aforementioned membrane resistance range.

[0039] A separator having a coating formed from a composition for coating may reduce battery reliability due to the aforementioned increase in dry heat shrinkage. The composition for coating includes a (meth)acrylic acid binder but does not include aziridine crosslinking agents as crosslinking agents, or includes crosslinking agents other than aziridine crosslinking agents. According to one example embodiment, aziridine crosslinking agents may be included in the composition for coating in an amount of about 95 wt% or more (e.g., in the range of about 98 wt% to about 100 wt% or 100 wt%) of the total crosslinking agents.

[0040] A separator having a coating formed from a composition for coating has high membrane resistance and high permeability, which may pose challenges to battery capacity, lifespan, and safety. The composition for coating includes an aziridine crosslinking agent but does not include a (meth)acrylic acid binder, or includes binders other than a (meth)acrylic acid binder. According to one example embodiment, the (meth)acrylic acid binder may be included in the composition for coating in an amount of about 95 wt% or more of the total binder (e.g., in the range of about 98 wt% to about 100 wt% or 100 wt%).

[0041] The filler includes a mixture of a first filler and a second filler. A diaphragm formed from a composition for coating that includes only the first filler may have a high dry heat shrinkage rate. A diaphragm formed from a composition for coating that includes only the second filler may also have a high dry heat shrinkage rate. According to one example embodiment, a mixture of the first and second fillers may be included in the composition for coating in an amount of about 95 wt% or more of the total filler (e.g., in the range of about 98 wt% to about 100 wt% or 100 wt%).

[0042] First coating layer The adhesive includes a (meth)acrylic adhesive, which comprises a first structural unit derived from (meth)acrylic acid, (meth)acrylate or a salt thereof, a second structural unit derived from (meth)acrylic acid hydroxyalkyl ester or a third structural unit derived from (meth)acrylamidosulfonic acid or a salt thereof.

[0043] According to one example embodiment, the (meth)acrylic adhesive may be or include a non-adhesive adhesive.

[0044] According to one example embodiment, the (meth)acrylic acid binder may be or includes a salt binder, such as an alkali metal salt binder. Here, the alkali metal may be or includes at least one of lithium, sodium, potassium, rubidium, and cesium. In this case, it is possible to reduce the membrane resistance of the diaphragm.

[0045] (Meth)acrylic acid binders can fix fillers onto porous substrates, enabling the first coating layer to adhere to both the porous substrate and the electrodes, and contributing to improved heat resistance, permeability, and oxidation resistance of the membrane. Furthermore, (meth)acrylic acid binders can promote lithium-ion movement, thereby reducing membrane resistance and improving ionic conductivity, increasing the adhesion of the first coating layer to the porous substrate and electrodes, and increasing the dispersion of fillers within the coating layer. Additionally, (meth)acrylic acid binders can provide a membrane with low membrane resistance and low dry heat shrinkage in a first coating layer comprising the fillers described below.

[0046] Based on 100 mol% (meth)acrylic acid binder, the sum of the contents of the first, second, and third structural units can be about 95 mol% or greater (e.g., in the range of about 95 mol% to about 100 mol%, for example, 100 mol%). Within the above range, the above-mentioned membrane effect can be easily achieved.

[0047] The first structural unit is derived from (meth)acrylic acid, (meth)acrylate, or a salt thereof, and can fix the filler on a porous substrate while providing adhesion, allowing the coating to adhere to the porous substrate and the electrode, and can help improve the heat resistance and permeability of the diaphragm. Additionally, the first structural unit can improve the dispersibility of the composition used for the coating by having a carboxyl functional group (-C(=O)O-) within the structural unit.

[0048] The first structural unit can be represented by any one of the following chemical formulas 1 to 3: Chemical Formula 1: Chemical Formula 2: Chemical Formula 3: ; ; .

[0049] Based on a 100 mol% binder for rechargeable lithium batteries, the first structural unit can be in the form of about 20 mol% to about 75 mol% (e.g., 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 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%, 45 mol%, 46 mol%, 47 mol%, 48 mol%). The amounts included are within the range of 49 mol%, 50 mol%, 51 mol%, 52 mol%, 53 mol%, 54 mol%, 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%, from 25 mol% to 70 mol%, from 30 mol% to 65 mol%, from 30 mol% to 60 mol%, or from 40 mol% to 65 mol%. When the first structural unit is included within the above range, the diaphragm can exhibit low membrane resistance, desired or improved adhesion to porous substrates and electrodes, heat resistance, air permeability, and oxidation resistance.

[0050] According to an example embodiment, the first structural unit may include structural units represented by chemical formula 2 and structural units represented by chemical formula 3, wherein 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, about 10:1 to about 1:1 or about 5:1 to about 1:1.

[0051] According to another example embodiment, the first structural unit may consist only of structural units represented by chemical formula 2 or chemical formula 3.

[0052] The second structural unit is derived from hydroxyalkyl (meth)acrylate and can immobilize the filler onto the porous substrate while providing adhesion, allowing the coating to adhere to both the porous substrate and the electrode. Furthermore, the second structural unit can improve the dispersibility of the composition used for the coating by having a carboxyl functional group (-C(=O)O-) within the structural unit.

[0053] The second structural unit can be represented by the following chemical formula 4: Chemical formula 4: .

[0054] Based on 100 mol% of the binder for rechargeable lithium batteries, the second structural unit can be included in an amount ranging from about 1 mol% to about 20 mol% (e.g., 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%, 2 mol% to 15 mol%, 5 mol% to 15 mol%, or 5 mol% to 10 mol%). Within the above range, it is possible to increase the adhesion of the coating to the porous substrate and the electrode.

[0055] The second structural unit may be or include, for example, structural units derived from (meth)acrylate hydroxyalkyl esters. Here, alkyl may be or include C1 to C20 alkyl, C1 to C10 alkyl, or C1 to C6 alkyl.

[0056] Hydroxyalkyl methacrylates may include one or more of, for example, hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, and 6-hydroxyhexyl methacrylate.

[0057] The third structural unit derived from (meth)acrylamide sulfonic acid or its salt can reduce the membrane resistance of the separator by increasing the likelihood of lithium ion movement in the presence of the first and second structural units.

[0058] By including bulky functional groups derived from (meth)acrylamide sulfonic acid or its salts, the third structural unit can enhance the heat resistance of the membrane due to the increase in glass transition temperature. When the third structural unit includes a functional group derived from a salt of (meth)acrylamide sulfonic acid, the metal (M) can move through the third structural unit by substituting the sulfonic acid functional group containing the metal (M), thereby exhibiting the effect of reducing membrane resistance.

[0059] The third structural unit can be represented by the following chemical formulas 5, 6, 7, or combinations thereof: Chemical formula 5: Chemical formula 6: Chemical formula 7: ; ; .

[0060] The third structural unit may include only one type or two or more types of structural units represented by chemical formula 5, chemical formula 6, and chemical formula 7. For example, the third structural unit may include a structural unit represented by chemical formula 6, and as another example, the third structural unit may include structural units represented by chemical formula 6 and structural units represented by chemical formula 7.

[0061] The third structural unit may be or includes, for example, a structural unit derived from (meth)acrylamidoalkyl sulfonic acid or a salt thereof. Here, the alkane may be or includes C1 to C20 alkanes, C1 to C10 alkanes, or C1 to C6 alkanes, and the alkyl may be or includes C1 to C20 alkyl, C1 to C10 alkyl, or C1 to C6 alkyl. A salt is defined as a salt consisting of or including the aforementioned sulfonic acid and a desired ion. The ion may be, for example, an alkali metal ion, in which case the salt may be or includes an alkali metal salt of a sulfonic acid.

[0062] For example, (meth)acrylamidoalkane sulfonic acid can be 2-(meth)acrylamido-2-methylpropane sulfonic acid.

[0063] In (meth)acrylic acid binders, the third structural unit may be present in an amount from about 20 mol% to about 75 mol% (e.g., 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 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%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%). The amounts of the third structural unit are included in the range of 50 mol%, 51 mol%, 52 mol%, 53 mol%, 54 mol%, 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%, 25 mol% to 70 mol%, 20 mol% to 65 mol%, 30 mol% to 65 mol%, or 30 mol% to 60 mol%. When the third structural unit is included in the above range, the (meth)acrylic acid binder and the diaphragm including the (meth)acrylic acid binder can exhibit significantly low membrane resistance.

[0064] The descriptions of chemical formulas 1 to 7 are as follows.

[0065] R 1 To R 14 They can all be or include hydrogen or C1 to C10 alkyl groups independently. For example, R 1 To R 7 and R 9 To R 14 It can be all or include hydrogen or methyl, R 8 It can be or include methyl.

[0066] L 1 To L 4 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 divalent heterocyclic groups. For example, L 1 It may include or contain methylene or ethylene, and L 2 To L 4 They can all be independently * -C(CH3)2-CH2- * .

[0067] a, b, c, and d can each be an integer in the range of 0 to 2. For example, a, b, c, and d can all be equal to 1.

[0068] M can be or includes an alkali metal, which can be or includes lithium, sodium, potassium, rubidium, or cesium. For example, M can be lithium or sodium.

[0069] A representative example of a (meth)acrylic adhesive according to an exemplary embodiment is shown in the following chemical formula 8: Chemical formula 8: .

[0070] The description of the above chemical formula 8 is as follows.

[0071] R 15 To R 20 They can all be or include hydrogen or C1 to C10 alkyl groups independently. For example, R 15 To R 17 and R 19 and R 20 It can be all or include hydrogen or methyl, and R 18 It can be or include methyl.

[0072] L 5 and L 6Each 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 divalent heterocyclic groups. For example, L 5 It may include or contain methylene or ethylene, L 6 It can be or include * -C(CH3)2-CH2- * .

[0073] M can be or includes an alkali metal, which can be or includes lithium, sodium, potassium, rubidium, or cesium. For example, M can be lithium or sodium.

[0074] e and f can both be independent integers in the range of 0 to 2. For example, e and f can both be equal to 1.

[0075] l, m, and n can be the molar ratio of each unit, and l + m + n = 1. For example, 0.20 ≤ l ≤ 0.75, 0.01 ≤ m ≤ 0.2, and 0.2 ≤ n ≤ 0.75; or 0.25 ≤ l ≤ 0.70, 0.01 ≤ m ≤ 0.15, and 0.25 ≤ n ≤ 0.75; or 0.3 ≤ l ≤ 0.65, 0.05 ≤ m ≤ 0.15, and 0.3 ≤ n ≤ 0.65.

[0076] (Meth)acrylic binders may include alkali metals. Alkali metals can exist in cationic form, such as lithium, sodium, potassium, rubidium, or cesium. For example, alkali metals can exist as salts bound to the (meth)acrylic binder. Alkali metals can assist in the synthesis of (meth)acrylic binders in aqueous solvents, improve the adhesion of the coating, and enhance the heat resistance, permeability, and oxidation resistance of the membrane.

[0077] Alkali metals may be included in an amount ranging from about 1 wt% to about 40 wt% (e.g., 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 10 wt% to 20 wt%) of the alkali metal and (meth)acrylic binder. For example, the (meth)acrylic binder and alkali metals may be included in a weight ratio ranging from about 99:1 to about 60:40, or a weight ratio of 99:1 to 70:30 (e.g., a weight ratio of 99:1 to 80:20, or, for example, a weight ratio of 90:10 to 80:20).

[0078] Based on the total content of alkali metal and (meth)acrylic binder, the alkali metal may be included in an amount ranging from about 0.1 mol% to about 1.0 mol%. When the alkali metal is included within the above range, the coating may have desired or improved adhesion, and the diaphragm including the coating may exhibit desired or improved heat resistance, air permeability, and oxidation resistance.

[0079] (Meth)acrylic adhesives can take various forms, such as alternating polymers in which structural units are distributed alternately, random polymers in which structural units are distributed randomly, or grafted polymers in which some of the structural units are grafted.

[0080] The weight-average molecular weight of (meth)acrylic acid adhesives can range from about 100,000 g / mol to about 1,000,000 g / mol, 100,000 g / mol to 500,000 g / mol, 100,000 g / mol to 150,000 g / mol, 130,000 g / mol to 200,000 g / mol, or 300,000 g / mol to 900,000 g / mol. When the weight-average molecular weight of the (meth)acrylic acid adhesive meets the above ranges, the (meth)acrylic acid adhesive can exhibit desired or improved adhesion and low electrical resistance. The weight-average molecular weight can be or includes the average molecular weight converted from polystyrene as measured by gel permeation chromatography.

[0081] (Meth)acrylic acid binders can be prepared by solution polymerization.

[0082] According to one example embodiment, the (meth)acrylic adhesive may be included in the coating layer of the diaphragm in the form of a film.

[0083] Crosslinking agents include aziridine crosslinking agents.

[0084] Aziridine crosslinking agents can crosslink (meth)acrylic acid binders to promote the membrane to achieve the aforementioned thermal shrinkage rate range in the electrolyte. Additionally, aziridine crosslinking agents can crosslink (meth)acrylic acid binders to significantly reduce the membrane resistance. Furthermore, aziridine crosslinking agents can crosslink (meth)acrylic acid binders to increase adhesion to the electrodes.

[0085] 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 within the molecule. According to an example embodiment, aziridine crosslinking agents can be or include aziridine crosslinking agents with bifunctional or trifunctional groups.

[0086] For example, aziridine crosslinking agents may include at least one 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).

[0087] Crosslinking agents (e.g., aziridine crosslinking agents) may be included in a desired amount relative to the adhesive (e.g., (meth)acrylic acid adhesive). According to an example embodiment, based on 100 parts by weight of the (meth)acrylic acid adhesive, the crosslinking agent may be included in amounts from about 5 parts by weight to about 50 parts by weight (e.g., 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, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, etc.). The amounts are included in the range of 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, 50 parts by weight, 5 to 30 parts by weight, 5 to 25 parts by weight, or 5 to 20 parts by weight. Within the above ranges, the thermal shrinkage rate and membrane resistance of the diaphragm in the electrolyte can be significantly reduced.

[0088] The packing material includes a mixture of a first packing material and a second packing material, wherein the first packing material is an inorganic packing material and the second packing material is an MOF structure.

[0089] The first filler may have an average particle size D50 in the range of about 100 nm to about 200 nm (e.g., 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 120 nm to 180 nm or 150 nm). Within the above range, when the first filler is combined with the MOF described below, the above-mentioned dry heat shrinkage rate and wet heat shrinkage rate can be achieved.

[0090] The first filler may be or include ceramic materials as inorganic fillers. Inorganic fillers may include at least one of metal oxides, quasi-metal oxides, metal fluorides, metal hydroxides, and 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, and combinations thereof, but are not limited thereto. For example, the inorganic filler may be boehmite.

[0091] The first filler can be spherical, plate-shaped, cubic, or amorphous. Preferably, the first filler can be cubic, in which case the aforementioned heat shrinkage rate can be significantly reduced.

[0092] The second filler may include a compound in which a metal cation and a linker are coordinated and bonded. For example, the second filler may be or include a microporous crystal consisting of a metal or metal cluster and a linker that links the metal or metal cluster by coordination bonds, or a metal or metal cluster and a linker that links the metal or metal cluster by coordination bonds.

[0093] In one example embodiment, the second filler may include a metal ion (such as a zinc ion or a cobalt ion) linked by a coordination bond and an imidazole compound (or a derivative of an imidazole compound) as a linking group. The imidazole compound may be or include one or more of imidazole, methylimidazolium containing 2-methylimidazolium, and benzimidazole. The nitrogen atom of the imidazole compound may form a coordination bond with at least one of the metal ions.

[0094] The second filler may include zeolite imidazole ester skeleton (ZIF) compounds, such as ZIF-8.

[0095] The second filler may have an average particle size D50 in the range of about 100 nm to about 200 nm (e.g., 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 120 nm to 180 nm or 150 nm). Within the above range, when the second filler is combined with the first filler, the above-mentioned dry heat shrinkage rate and wet heat shrinkage rate can be achieved.

[0096] Based on 100 parts by weight of the mixture, the first filler and the second filler can be included in a weight ratio ranging from about 50:50 to about 95:5. Within this range, it is advantageous to reduce dry heat shrinkage and wet heat shrinkage. For example, the weight ratio can be in the range of 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, about 50:50 to about 90:10, or 80:20 to 90:10, and within this range, the rate characteristics can be further improved.

[0097] The filler (i.e., the mixture) and (meth)acrylic binder can be included in a (meth)acrylic binder:mixture mass ratio in the range of about 1:10 to about 1:50 (e.g., 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:10 to 1:40, or 1:20 to 1:30). Within the above range, it can have the effect of improving the heat resistance within the electrolyte.

[0098] The filler (i.e., the mixture) may be included in an amount ranging from about 50 wt% to about 99 wt% of the total amount of the coating (e.g., 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%, 95 wt% to 99 wt%). When the filler is included within the above range, desired or improved heat resistance, durability, oxidation resistance, and stability may be exhibited.

[0099] Adhesive binders are or include (meth)acrylic adhesive binders. (meth)acrylic adhesive binders can increase adhesion to the negative electrode. Adhesive binders can be granular and cross-linked.

[0100] (Meth)acrylate adhesives may include (meth)acrylate polymers or copolymers. According to one example embodiment, the adhesive may be or include crosslinked (meth)acrylate polymers or copolymers. For example, the adhesive may include crosslinked polymethyl methacrylate (PMMA) polymers.

[0101] To prepare the crosslinked (meth)acrylic acid polymer, a crosslinking agent can be further added during the polymerization step. The (meth)acrylic acid adhesive can have a glass transition temperature in the range of about 50°C to about 110°C (e.g., 50°C to 70°C). Within this range, not only is electrode adhesion desired or improved, but good ionic conductivity is also expected. The glass transition temperature can be measured using differential scanning calorimetry (DSC). For example, after placing 2 mg of the polymer in a pressure pan for DSC measurement, the temperature range is set to 25°C to 200°C, the heating rate is set to 10°C / min, and the glass transition temperature is obtained under a controlled atmosphere.

[0102] Based on 100 parts by weight of (meth)acrylic acid adhesive, the (meth)acrylic acid adhesive can be used in quantities from about 1 part by weight to about 100 parts by weight (e.g., 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 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, 22 parts by weight). Servings, 23 servings, 24 servings, 25 servings, 26 servings, 27 servings, 28 servings, 29 servings, 30 servings, 31 servings, 32 servings, 33 servings, 34 servings, 35 servings, 36 servings, 37 servings, 38 servings, 39 servings, 40 servings, 41 servings, 42 servings, 43 servings, 44 servings, 45 servings, 46 servings, 47 servings, 48 ​​servings, 49 servings, 50 servings, 51 servings 52 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight. The quantities included are within the range of 81 parts by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, 100 parts by weight, 1 to 50 parts by weight, 1 to 30 parts by weight, 5 to 30 parts by weight, or 5 to 20 parts by weight.

[0103] The first coating layer may have a thickness in the range of about 0.01 μm to about 20 μm, within which the thickness may be 0.01 μm to 7 μm, 0.1 μm to 5 μm, or 0.1 μm to 3 μm. For example, the first coating layer may have a thickness of 0.1 μm to 2 μm.

[0104] The ratio of the thickness of the first coating layer to the thickness of the porous substrate can be in the range of about 0.01 to about 0.7 (e.g., 0.01 to 0.5, 0.01 to 0.4, or 0.01 to 0.3). Within the above range, the diaphragm can exhibit desired or improved permeability, heat resistance, and adhesion.

[0105] Second coating layer The second coating layer may be formed from a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and an adhesive, or from a composition comprising a (meth)acrylic adhesive, an aziridine crosslinking agent, a filler, and an adhesive.

[0106] The detailed composition of each of the (meth)acrylic binder, aziridine crosslinking agent, and filler is substantially the same as that described in the first coating layer. Therefore, their detailed descriptions are omitted.

[0107] Adhesive binders are or include fluorinated adhesive binders having a carbonyl group (C=O). Fluorinated adhesive binders can be advantageous in providing high adhesion to the positive electrode.

[0108] Fluorinated adhesives are or include particulate aqueous adhesives, and may include at least one fluorinated adhesive having a carbonyl group (C=O) and a hydroxyl group (OH), such as polyvinylidene fluoride (PVDF) adhesives having both carbonyl and hydroxyl groups. Fluorinated adhesives having both carbonyl and hydroxyl groups can be advantageous in increasing adhesion to the positive electrode.

[0109] Polyvinylidene fluoride (PVDF) adhesives may include structural units derived from PVDF and structural units derived from monomers having at least one carbonyl and one hydroxyl group. Structural units derived from monomers having at least one carbonyl and one hydroxyl group can provide improved adhesion, durability, and breathability. Monomers having at least one carbonyl and one hydroxyl group may be or include at least one of (meth)acrylic acid, itaconic acid or derivatives thereof, maleic acid or derivatives thereof, and hydroxyalkyl allyl ethers.

[0110] Polyvinylidene fluoride (PVDF) adhesives may also include structural units derived from monomers that are copolymerizable with PVDF. The copolymerizable monomers may be, or include, at least one of trichloroethylene, chlorotrifluoroethylene, trifluoroethylene, hexafluoropropylene, tetrafluoroethylene, and ethylene monomers.

[0111] According to one example embodiment, a polyvinylidene fluoride-based adhesive is or includes a copolymer of vinylidene fluoride, a monomer having carbonyl and hydroxyl groups, and hexafluoropropylene, and may include structural units derived from vinylidene fluoride, structural units derived from monomers having carbonyl and hydroxyl groups, and structural units derived from hexafluoropropylene.

[0112] In one example embodiment, the polyvinylidene fluoride-based adhesive may include polyvinylidene fluoride repeating units ranging from about 65 mol% to about 99 mol% (e.g., 80 mol% to 99 mol% or 65 mol% to 85 mol%), hexafluoropropylene repeating units ranging from about 10 mol% to about 25 mol%, and repeating units derived from monomers having carbonyl and hydroxyl groups ranging from about 0.5 mol% to about 10 mol%.

[0113] In one example embodiment, based on a total amount of 100 mol% of vinylidene fluoride and hexafluoropropylene, the polyvinylidene fluoride-based adhesive comprises repeating units derived from vinylidene fluoride ranging from about 75 mol% to about 90 mol% and repeating units derived from hexafluoropropylene ranging from about 10 mol% to about 25 mol%, and may also include repeating units derived from monomers having carbonyl and hydroxyl groups.

[0114] Polyvinylidene fluoride (PVDF) adhesives can take various forms, such as alternating polymers in which structural units are distributed alternately, random polymers in which repeating units are distributed randomly, or grafted polymers in which some of the repeating units are grafted. Furthermore, PVDF adhesives can be or include linear polymers, branched polymers, or mixtures thereof.

[0115] The crystallinity of fluorinated adhesives can range from about 35% to about 65% (e.g., 40% to 60% or 40% to 55%). In this range, the fluorinated adhesive can exhibit desired or improved adhesion. Crystallinity can be measured using DSC. Crystallinity is measured by adding 2 mg of the fluorinated adhesive to a pressure pan for DSC measurement and then heating it at a temperature range of 25°C to 200°C and a heating rate of 10°C / min. The above experiment was performed in a controlled environment.

[0116] The melting point of fluorinated adhesives can be about 150°C or higher, for example, in the range of about 150°C to about 200°C. The melting point can be measured using DSC. The melting point is measured by adding 2 mg of the fluorinated adhesive to a pressure pan for DSC measurement and then heating it at a temperature range of 25°C to 200°C and a heating rate of 10°C / min. The above experiment was performed in a controlled environment.

[0117] Fluorinated adhesives can have a weight-average molecular weight in the range of about 100,000 g / mol to about 1,500,000 g / mol (e.g., 200,000 g / mol to 800,000 g / mol). The weight-average molecular weight can be obtained as a polystyrene equivalent by gel permeation chromatography.

[0118] Fluorine-based adhesive binders can have a swelling ratio of approximately 70% or greater. Within this range, by dispersing the stress accumulated in the negative electrode during charging and discharging processes via the expanded binder, electrode assembly deformation can be effectively reduced or prevented. The swelling ratio is calculated by measuring the volume of the binder before immersion in the electrolyte and comparing the measured volume with the volume after immersion in the electrolyte.

[0119] Fluorine-based adhesives can be prepared by various known methods, such as emulsion polymerization, suspension polymerization, bulk polymerization, or solution polymerization, and for example, by emulsion polymerization.

[0120] Based on 100 parts by weight of (meth)acrylic acid adhesive, fluorinated adhesives can be used in quantities from about 1 part by weight to about 100 parts by weight (e.g., 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 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, 22 parts by weight, 2...). 3 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, 50 parts by weight, 51 parts by weight, 5 2 parts by weight, 53 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 57 parts by weight, 58 parts by weight, 59 parts by weight, 60 parts by weight, 61 parts by weight, 62 parts by weight, 63 parts by weight, 64 parts by weight, 65 parts by weight, 66 parts by weight, 67 parts by weight, 68 parts by weight, 69 parts by weight, 70 parts by weight, 71 parts by weight, 72 parts by weight, 73 parts by weight, 74 parts by weight, 75 parts by weight, 76 parts by weight, 77 parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight, 8 The quantities included are within the range of 1 part by weight, 82 parts by weight, 83 parts by weight, 84 parts by weight, 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, 95 parts by weight, 96 parts by weight, 97 parts by weight, 98 parts by weight, 99 parts by weight, 100 parts by weight, 1 to 50 parts by weight, 1 to 30 parts by weight, 5 to 30 parts by weight, or 5 to 20 parts by weight.

[0121] Porous substrate Porous substrates have a large number of pores and may be or include substrates commonly used in electrochemical devices. Porous substrates may be, but are not limited to, polymer membranes formed from or comprising a polymer such as polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetheretherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfide, glass fibers, and polytetrafluoroethylene (such as Teflon), or copolymers or mixtures of two or more of these.

[0122] 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, and thus can contribute to improved battery safety. The polyolefin substrate can be or includes at least one of, for example, polyethylene monolayer membranes, polypropylene monolayer membranes, polyethylene / polypropylene bilayer membranes, polypropylene / polyethylene / polypropylene trilayer membranes, and polyethylene / polypropylene / polyethylene trilayer membranes. In addition to olefin resins, polyolefin resins can also include non-olefin resins, or can include copolymers of olefin and non-olefin monomers.

[0123] Porous substrates can have a thickness ranging from about 1 μm to about 40 μm (e.g., 1 μm to 30 μm, 1 μm to 20 μm, or 5 μm to 15 μm).

[0124] Porous substrates can have a permeability of less than about 200 sec / 100 cc (e.g., 190 sec / 100 cc or less, or 180 sec / 100 cc or less). Within the above range, porous substrates can be used in membranes.

[0125] A separator for a rechargeable lithium battery according to an example embodiment can be formed by applying a composition for forming a coating layer to one or both sides of a porous substrate and then drying the composition. Drying can be performed using conventional methods known to those skilled in the art.

[0126] Figure 1 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment.

[0127] Reference Figure 1 The separator for a rechargeable lithium battery includes a porous substrate 1, a first coating layer 2a located on a first surface of the porous substrate 1, and a second coating layer 2b located on a second surface of the porous substrate 1. The first coating layer 2a may include a crosslinking product 3 of a (meth)acrylic acid binder and an aziridine crosslinking agent, a first filler 4, a second filler 5, and a first adhesive binder 6. The second coating layer 2b may include the crosslinking product 3 of a (meth)acrylic acid binder and an aziridine crosslinking agent, the first filler 4, the second filler 5, and a second adhesive binder 7.

[0128] Rechargeable lithium batteries Another example embodiment includes a rechargeable lithium battery comprising a separator, a positive electrode, and a negative electrode according to an example embodiment.

[0129] The separator used in rechargeable lithium batteries is as described above. The separator used in rechargeable lithium batteries can be located between the positive electrode and the negative electrode.

[0130] 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 positive electrode active material and may also include a binder and / or conductive material. For example, the positive electrode may also include additives that can constitute a sacrificial positive electrode.

[0131] Positive electrode active material 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.

[0132] 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, and combinations thereof.

[0133] 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 eO2 (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).

[0134] In the above chemical formula, A is or includes at least one of Ni, Co, Mn, and combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is or includes at least one of O, F, S, P, and combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; and L 1 It is or includes at least one of Mn, Al and combinations thereof.

[0135] 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.

[0136] 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 amount of each of the binder and conductive material can each independently range from about 0.5 wt% to about 5 wt%.

[0137] 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.

[0138] Conductive materials can impart electrical conductivity (e.g., electroconductivity) to electrodes. Any material that does not cause chemical changes in the battery (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used. 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, 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.

[0139] Al can be used as a current collector, but current collectors are not limited to this.

[0140] 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).

[0141] For example, the negative electrode active material layer may include about 90 wt% to about 99 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder, and about 0 wt% to about 5 wt% of conductive material.

[0142] Negative electrode active material The negative electrode active material may include at least one of the following: materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium metal alloys, materials capable of doping / dedoping lithium, and transition metal oxides.

[0143] Materials capable of reversibly embedding / desorbing lithium ions may include carbonaceous negative electrode active materials, 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 in amorphous, flaky, lamellar, spherical, or fibrous form. Amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0144] Lithium metal alloys include alloys of lithium and metals (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).

[0145] Materials capable of doping / undoping lithium may be or include Si-based negative electrode active materials or Sn-based negative electrode active materials. Si-based negative electrode active materials may include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (where Q is or includes at least one of alkali metals, alkaline earth metals, group 13 elements, group 14 elements (except Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof). Sn-based negative electrode active materials may include at least one of Sn, SnO2, Sn-based alloys, and combinations thereof.

[0146] Silicon-carbon composites may be or include composites 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 layer (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.

[0147] The silicon-carbon composite may also include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core.

[0148] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used in combination with carbonaceous negative electrode active materials.

[0149] The binder may attach negative electrode active material particles to each other and may attach the negative electrode active material to the current collector. The binder may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0150] 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, and combinations thereof.

[0151] 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.

[0152] 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, and their alkali metal salts. The alkali metal may include at least one of Na, K, and Li.

[0153] Dry adhesives can be or include polymeric materials capable of being fibrous. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and combinations thereof.

[0154] Conductive materials can impart electrical conductivity (e.g., electroconductivity) to electrodes. Any material that does not cause chemical changes in the battery (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used. Non-limiting examples 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.

[0155] The negative electrode current collector may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with a conductive metal, and combinations thereof.

[0156] Rechargeable lithium batteries may also include an electrolyte.

[0157] electrolyte Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0158] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0159] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and combinations thereof.

[0160] 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).

[0161] 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.

[0162] 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. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc. Aprotic solvents may include at least one of the following: 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.

[0163] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0164] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed together, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0165] 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 F2y+1 At least one of the following: (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), lithium difluoro(oxalate)borate (LiDFOB), and lithium bis(oxalate)borate (LiBOB).

[0166] Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch, or coin-shaped batteries.

[0167] 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 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 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative terminal 22 connected to the negative electrode lead connector 21. 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 in the figure form an electrical path for guiding the current formed in the electrode assembly 40 to the outside of the rechargeable lithium battery 100.

[0168] 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.

[0169] Examples and comparative examples of this disclosure are described below. However, the following examples are merely examples of this disclosure, and this disclosure is not limited to these examples.

[0170] Preparation Example 1 Distilled water (1249.72 g), 20% lithium hydroxide aqueous solution (203.69 g), acrylic acid (AA, 0.3 mol), 2-hydroxyethyl methacrylate (HEMA, 0.10 mol), 2-acrylamido-2-methylpropanesulfonic acid (AMPS, 0.6 mol), and ammonium persulfate (0.2 g, 0.001 mol) were added to a 3L four-necked separable flask equipped with a stirrer, thermometer, and condenser. The internal pressure was then reduced to 10 mmHg using a diaphragm pump and restored to atmospheric pressure using nitrogen three times. The reaction was carried out for 12 hours while heating was controlled to stabilize the temperature of the reaction solution between 65°C and 70°C. After cooling to room temperature, approximately 10 mL of the reaction solution was taken and the content of non-volatile (NV) components was measured, which was 9.8 wt% (theoretical value: 10 wt%). In addition, in the obtained poly(lithium acrylate-co-hydroxyethyl methacrylate-co-2-acrylamido-2-methylpropanesulfonate lithium salt), the molar ratio of the first structural unit derived from lithium acrylate, the second structural unit derived from 2-hydroxyethyl methacrylate, and the third structural unit derived from 2-acrylamido-2-methylpropanesulfonate lithium salt is 30:10:60.

[0171] Preparation Example 2 In Preparation Example 1, the content of each monomer was varied to prepare poly(lithium acrylate-co-hydroxyethyl methacrylate-co-2-acrylamido-2-methylpropanesulfonate lithium salt). The molar ratio of the structural units derived from lithium acrylate, 2-hydroxyethyl methacrylate, and 2-acrylamido-2-methylpropanesulfonate lithium salt was 40:10:50. Approximately 10 mL of the reaction solution (reaction product) was taken, and the content of the non-volatile component was measured to be 9.0 wt% (theoretical value: 10 wt%).

[0172] Preparation Example 3 In Preparation Example 1, the content of each monomer was varied to prepare poly(lithium acrylate-co-hydroxyethyl methacrylate-co-2-acrylamido-2-methylpropanesulfonate lithium salt). The molar ratio of the structural units derived from lithium acrylate, 2-hydroxyethyl methacrylate, and 2-acrylamido-2-methylpropanesulfonate lithium salt was 65:5:30. Approximately 10 mL of the reaction solution (reaction product) was taken, and the content of the non-volatile component was measured to be 9.0 wt% (theoretical value: 10 wt%).

[0173] Preparation Example 4 In Preparation Example 1, the content of each monomer was varied to prepare poly(lithium acrylate-co-hydroxyethyl methacrylate-co-2-acrylamido-2-methylpropanesulfonate lithium salt). The molar ratio of the structural units derived from lithium acrylate, 2-hydroxyethyl methacrylate, and 2-acrylamido-2-methylpropanesulfonate lithium salt was 40:5:55. Approximately 10 mL of the reaction solution (reaction product) was taken, and the content of the non-volatile component was measured to be 9.0 wt% (theoretical value: 10 wt%).

[0174] Preparation Example 5 The acrylic copolymer was prepared in the same manner as in Preparation Example 1, except that 2-hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid were used and acrylic acid was not used. The molar ratio of the structural units derived from 2-hydroxyethyl methacrylate and lithium 2-acrylamido-2-methylpropanesulfonic acid, respectively, was 74:26. ​​The content of the non-volatile component in the reaction solution was 9.0 wt% (theoretical value: 10 wt%).

[0175] Preparation Example 6 The acrylic copolymer was prepared in the same manner as in Preparation Example 1, except that acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid were used and 2-hydroxyethyl methacrylate was not used. The molar ratio of the structural units derived from acrylic acid and lithium 2-acrylamido-2-methylpropanesulfonic acid salt was 74:26. ​​The content of the nonvolatile component in the reaction solution was 9.0 wt% (theoretical value: 10 wt%).

[0176] Preparation Example 7 The acrylic copolymer was prepared in the same manner as in Preparation Example 1, except that acrylic acid and 2-hydroxyethyl methacrylate were used and 2-acrylamido-2-methylpropanesulfonic acid was not used. The molar ratio of the structural units derived from lithium acrylate and 2-hydroxyethyl methacrylate, respectively, was 42:58. The content of the nonvolatile components in the reaction solution was 9.0 wt% (theoretical value: 10 wt%).

[0177] Example 1 (1) Based on a total of 100 parts by weight, boehmite (particle size D50: 150 nm, KB-01S of DAEJOO KC Ltd, cubic) as the first filler and ZIF-8 (particle size D50: 150 nm, which is MOF) as the second filler were mixed at a weight ratio of 90:10 to prepare a mixture.

[0178] The (meth)acrylic binder (10 wt% in distilled water) prepared in Preparation Example 1 and the mixture prepared above were mixed at a (meth)acrylic binder:filler mass ratio of 1:20, added to an aqueous solvent, and then ground and dispersed at 25°C for 30 minutes using a bead mill to prepare a dispersion.

[0179] Trimethylolpropane tris(2-methyl-1-aziridine propionate), a trifunctional aziridine crosslinking agent, was added to the dispersion, and water was added to make the total solid content 20 wt%. At this point, the aziridine crosslinking agent was included in an amount of 10 parts by weight based on 100 parts by weight of methacrylic acid binder.

[0180] Based on 100 parts by weight of methacrylic acid binder, 10 parts by weight of cross-linked polymethyl methacrylate (Tg: 60°C) as an adhesive binder were added to the resulting dispersion to prepare a composition for the first coating layer.

[0181] (2) Prepare a dispersion comprising the mixture of methacrylic acid binder, filler, and aziridine crosslinker prepared in Preparation Example 1 in the same manner as in (1). Add 10 parts by weight of polyvinylidene fluoride adhesive (75130, comprising a copolymer of vinylidene fluoride and hexafluoropropylene in a molar ratio of 90:10 and also comprising acrylic acid as a monomer, melting point: 154°C, crystallinity: 53%) based on 100 parts by weight of methacrylic acid binder to the above dispersion to prepare a composition for the second coating layer.

[0182] (3) The composition of the first coating layer is applied to the first surface of a polyethylene membrane (thickness: 5.5 μm, CZMZ, air permeability: 110 sec / 100 cc, puncture strength: 340 kgf) as a porous substrate using a molding method, and the composition for the second coating layer is applied to the second surface of the membrane using a molding method. The membrane is then dried and aged in an oven at 70°C for 16 hours to form the first coating layer (thickness: 1 μm) and the second coating layer (thickness: 1 μm), thereby manufacturing a separator for a rechargeable lithium battery.

[0183] Example 2 The diaphragm is prepared in the same manner as in Example 1, except that the weight ratio between the fillers in Example 1 is changed to 80:20.

[0184] Example 3 The diaphragm is prepared in the same manner as in Example 1, except that the weight ratio between the fillers in Example 1 is changed to 50:50.

[0185] Examples 4 to 6 Except for the type of binder as shown in Table 1 below, which is changed and used in place of the binder in Preparation Example 1, the membrane is prepared in the same manner as in Example 1.

[0186] Comparison Example 1 The diaphragm is prepared in the same manner as in Example 1, except that the first filler is not used in Example 1.

[0187] Comparison Example 2 The membrane was prepared in the same manner as in Example 1, except that a second filler was not used in Example 1.

[0188] Compare Example 3 The membrane was prepared in the same manner as in Example 1, except that no aziridine crosslinking agent was used in Example 1.

[0189] Compare Example 4 Except that a polyvinylidene fluoride-based adhesive is used as the adhesive in the first coating layer in Example 1, the diaphragm is prepared in the same manner as in Example 1.

[0190] Compare Example 5 The diaphragm was prepared in the same manner as in Example 1, except that cross-linked polymethyl methacrylate was used as the adhesive binder in the second coating layer in Example 1.

[0191] Comparison Examples 6 to 8 Except for the type of binder as shown in Table 1 below, which is changed and used in place of the binder in Preparation Example 1, the membrane is prepared in the same manner as in Example 1.

[0192] Compare Example 9 Except that ethylene glycol diglycidyl ether (an epoxy crosslinking agent) is used instead of the aziridine crosslinking agent in Example 1, the membrane is prepared in the same manner as in Example 1.

[0193] Compare Example 10 Except that CARBODILITE V-50 (Nisshinbo Chemical) was used as a carbodiimide (CDI) crosslinking agent instead of the aziridine crosslinking agent in Example 1, the membrane was prepared in the same manner as in Example 1.

[0194] Battery manufacturing Manufacturing of the negative electrode: The negative electrode is manufactured according to the following process.

[0195] A slurry of negative electrode active material was prepared by mixing 97 wt% graphite particles with an average particle size of 25 μm, 1.5 wt% styrene-butadiene rubber (SBR) binder, and 1.5 wt% carboxymethyl cellulose (CMC). The mixture was then added to distilled water and stirred using a mechanical stirrer for 60 minutes. The slurry was applied to a 10 μm thick copper current collector using a doctor blade, dried in a hot air dryer at 100°C for 0.5 hours, and then dried again under vacuum at 120°C for 4 hours. Finally, the mixture was rolled to fabricate the negative electrode.

[0196] Manufacturing of the positive electrode: The positive electrode is manufactured according to the following process.

[0197] A mixture of 97 wt% LiCoO2, 1.5 wt% carbon black powder as a conductive material, and 1.5 wt% polyvinylidene fluoride (PVDF) was added to an N-methyl-2-pyrrolidone solvent and stirred for 30 minutes using a mechanical stirrer to prepare a slurry for the positive electrode active material. The slurry was then applied to a 20 μm thick aluminum current collector using a doctor blade, dried in a hot air dryer at 100°C for 0.5 hours, and then dried again at 120°C under vacuum for 4 hours. Finally, the mixture was rolled to fabricate the positive electrode.

[0198] Electrode assembly core: Each diaphragm obtained according to the example and comparative example is placed between the positive and negative electrodes fabricated above, and then wound to prepare the electrode assembly core. The core is inserted into a bag, electrolyte is injected, and the bag is vacuum-sealed. As the electrolyte, 1.3M LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 3:5:2 is used.

[0199] The electrode core inserted into the bag was pressed at 80°C for 3 minutes, while applying 11.7 kgf / cm². 2 The pressure is to manufacture rechargeable lithium batteries.

[0200] Dry heat shrinkage rate (unit: %) Each separator for the example and comparative examples of rechargeable lithium batteries was cut into 8cm × 8cm dimensions to prepare samples. After drawing a 5cm × 5cm square on the surface of the sample, the sample was placed between paper or alumina powder and allowed to stand in an oven at 130°C for 1 hour. It was then removed, and the dimensions of the drawn squares were measured. The shrinkage rate in each of the longitudinal (MD) and transverse (TD) directions was calculated. The shrinkage rate was calculated according to Formula 1 below.

[0201] Mathematical formula 1: Shrinkage rate = (L0-L1) / L0×100.

[0202] L0 is the initial length of the diaphragm, and L1 is the length of the diaphragm after standing at 130°C for 1 hour.

[0203] Adhesion to the positive electrode (unit: gf / mm) The separator was attached to the positive electrode (manufactured in the same manner as in "Battery Manufacturing") with the second coating layer of the separator facing the positive electrode, and then inserted into a bag. An electrolyte (1.3 M LiPF6 in a 3 / 5 / 2 (volume ratio) mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / diethyl carbonate (DEC)) was injected, and the resulting assembly was allowed to stand for 12 hours at 10 kgf / cm². 2 Up to 20 kgf / cm 2 It was pressed under pressure, at a temperature of 70°C to 90°C, and for 5 to 20 seconds, and then disassembled. After removing the diaphragm and positive electrode from the bag, the positive electrode and diaphragm were unfolded 180°, and the force required to separate the positive electrode from the diaphragm was measured using a tension meter (Tinius Olsen, HT400).

[0204] Adhesion to the negative electrode (unit: gf / mm) The separator was attached to the negative electrode (manufactured in the same manner as in "Battery Manufacturing") with the first coating layer of the separator facing the negative electrode, and then inserted into a bag. An electrolyte (1.3 M LiPF6 in a 3 / 5 / 2 (volume ratio) mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / diethyl carbonate (DEC)) was injected, and the resulting assembly was allowed to stand for 12 hours at 10 kgf / cm². 2 Up to 20 kgf / cm 2 It was pressed under pressure, at a temperature of 70°C to 90°C, and for 5 to 20 seconds, and then disassembled. After removing the diaphragm and negative electrode from the bag, the negative electrode and diaphragm were unfolded 180°, and the force required to separate the negative electrode from the diaphragm was measured using a tension meter (Tinius Olsen, HT400).

[0205] Membrane resistance (unit: Ω) The membrane resistance was evaluated as electrochemical impedance spectroscopy (EIS) resistance. Membranes prepared in the example and comparative examples were impregnated with an electrolyte (1.5 M LiPF6 dissolved in a mixed solvent of ethylene carbonate, methyl ethyl carbonate, and dimethyl carbonate (volume ratio 2 / 1 / 7)), mounted onto aluminum foil electrodes with leaded terminals, and sealed in an aluminum cask to fabricate a test cell. The resistance (Ω) of this test cell was measured at 20°C using AC impedance spectroscopy (measurement frequency 100 kHz).

[0206] Ratio characteristics (unit: %) Manufacture a single coin-sized full-cell battery, measure the discharge capacity at 1C, 3C, and 5C, and set the 5C capacity of Example 1 to 100% for relative comparison.

[0207] Table 1:

[0208] Table 2:

[0209] (Table 2 continued)

[0210] As shown in Table 1 above, the example separator for rechargeable lithium batteries can provide low thermal shrinkage, low film resistance, high adhesion to the electrode plates, and high rate performance during charging and discharging, thereby improving battery reliability.

[0211] According to one example embodiment, a separator for a rechargeable battery can improve battery capacity, safety, and lifespan by providing low thermal shrinkage, low film resistance, high adhesion to electrode plates, and high rate performance during charging and discharging.

[0212] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the disclosure, and the drawings, which also fall within the scope of the present disclosure.

Claims

1. A separator for a rechargeable battery, the separator comprising: Porous substrate; A first coating layer is located on the first surface of the porous substrate; as well as The second coating layer is located on the second surface of the porous substrate. The first coating layer comprises: a crosslinking product of an adhesive and a crosslinking agent; a filler; and a first adhesive; and the second coating layer comprises: the crosslinking product of the adhesive and the crosslinking agent; the filler; and a second adhesive. Both the adhesive in the first coating layer and the adhesive in the second coating layer comprise (meth)acrylic acid adhesives, which include a first structural unit derived from (meth)acrylic acid, (meth)acrylates, or salts thereof, a second structural unit derived from (meth)acrylate hydroxyalkyl esters, and a third structural unit derived from (meth)acrylamidosulfonic acid or salts thereof. The crosslinking agent includes aziridine crosslinking agents. The packing material comprises a mixture of a first packing material and a second packing material, wherein the first packing material is an inorganic packing material, and the second packing material has a metal-organic framework structure. The first adhesive in the first coating layer is a (meth)acrylic adhesive, and the second adhesive in the second coating layer is a fluorinated adhesive having a carbonyl group.

2. The diaphragm according to claim 1, wherein, The (meth)acrylic adhesive includes salt-based adhesives.

3. The diaphragm according to claim 1, wherein, Based on 100 parts by weight of the mixture, the first filler and the second filler are included in a weight ratio in the range of 50:50 to 95:

5.

4. The diaphragm according to claim 1, wherein, The first filler has an average particle size D50 in the range of 100 nm to 200 nm.

5. The diaphragm according to claim 1, wherein, The second filler comprises zinc or cobalt ions and imidazole compounds linked by coordination bonds.

6. The diaphragm according to claim 1, wherein, The second filler has an average particle size D50 in the range of 100 nm to 200 nm.

7. The diaphragm according to claim 1, wherein, The (meth)acrylic adhesive and the mixture are included in a mass ratio ranging from 1:10 to 1:

40.

8. 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).

9. The diaphragm according to claim 1, wherein, Based on 100 parts by weight of the (meth)acrylic adhesive, the crosslinking agent is included in an amount ranging from 5 parts by weight to 50 parts by weight.

10. The diaphragm according to claim 1, wherein, The first structural unit is represented by at least one of chemical formula 1, chemical formula 2, chemical formula 3, and combinations thereof: Chemical Formula 1: Chemical Formula 2: Chemical Formula 3: ； ； ； The second structural unit is represented by chemical formula 4: Chemical formula 4: ,and 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, R 1 To R 14 Each independently includes hydrogen or C1 to C10 alkyl groups. L 1 To L 4 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 divalent heterocyclic group. a, b, c, and d 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 is represented by chemical formula 8: Chemical formula 8: ； In chemical formula 8, R 15 To R 20 Each independently includes hydrogen or C1 to C10 alkyl groups. L 5 and L 6 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 divalent heterocyclic group. M includes alkali metals. Both e and f are independent integers in the range of 0 to 2, and l, m, and n are the molar ratios of each unit, and l + m + n = 1.

12. The diaphragm according to claim 1, wherein: Based on 100 mol% of the (meth)acrylic acid binder, The first structural unit is included in an amount ranging from 20 mol% to 75 mol%. The second structural unit is included in an amount ranging from 1 mol% to 20 mol%; and The third structural unit is included in an amount ranging from 20 mol% to 75 mol%.

13. The diaphragm according to claim 1, wherein, Based on 100 mol% of the (meth)acrylic adhesive, the sum of the contents of the first structural unit, the second structural unit, and the third structural unit is 95 mol% or greater.

14. The diaphragm according to claim 1, wherein, The (meth)acrylic adhesive has a glass transition temperature in the range of 50°C to 110°C.

15. The diaphragm according to claim 1, wherein, The fluorinated adhesives include fluorinated adhesives having carbonyl and hydroxyl groups.

16. A rechargeable battery, said rechargeable battery comprising: Positive electrode; negative electrode; as well as The diaphragm according to any one of claims 1 to 15 is located between the positive electrode and the negative electrode.

Images