Separator for rechargeable battery and rechargeable battery comprising the same

Abstract

The present disclosure relates to a separator for a rechargeable battery and a rechargeable battery including the same. The separator for a rechargeable battery includes a porous substrate and a coating layer formed on at least one surface of the porous substrate. The coating layer includes a binding layer including a binding core-shell binder having a core and a shell surrounding the core, and the shell has a functional group containing a -S-S- group at one end portion.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2025-0017140, filed on February 11, 2025, 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 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 rapidly increasing. Therefore, improving the performance of rechargeable lithium batteries can be advantageous.

[0004] Rechargeable lithium batteries typically include a positive electrode and a negative electrode containing active materials capable of inserting and deintercalating lithium ions, and generate electrical energy through oxidation and reduction reactions when lithium ions are deintercalated from the positive electrode and inserted into the negative electrode, and deintercalated from the negative electrode and inserted into the positive electrode.

[0005] The diaphragm includes a porous substrate and a coating formed on at least one surface of the porous substrate. The coating may include an adhesive, thereby increasing adhesion to both the positive and negative electrodes. Among such adhesives, organic adhesives (e.g., polyvinylidene fluoride (PVDF) adhesives) have desired or improved wet adhesion to the positive electrode, but their wet adhesion to the negative electrode may be relatively low compared to their wet adhesion to the positive electrode.

[0006] Therefore, high wet adhesion to each of the positive and negative electrodes can be advantageous. However, when the content of the adhesive binder is increased to increase the wet adhesion to each of the positive and negative electrodes, the membrane resistance may increase, and the permeability may increase. Summary of the Invention

[0007] This disclosure is intended to describe a separator for a rechargeable battery in which the adhesion to each of the positive and negative electrodes is significantly increased.

[0008] This disclosure also aims to describe a separator for rechargeable batteries in which increased adhesion is achieved between a porous substrate, a heat-resistant layer, and an adhesive layer.

[0009] This disclosure also aims to describe a separator with low resistance for rechargeable batteries.

[0010] This disclosure also aims to describe a separator for rechargeable batteries comprising a binder capable of increasing the dissociation of lithium ions and forming ion transport channels.

[0011] This disclosure is also intended to describe rechargeable batteries including a separator for rechargeable batteries.

[0012] According to an aspect of this disclosure, a separator for a rechargeable battery includes a porous substrate and a coating formed on at least one surface of the porous substrate. The coating includes an adhesive layer comprising an adhesive core-shell adhesive having a core and a shell surrounding the core, and the shell having a functional group containing an -SS- group at one end thereof.

[0013] According to another aspect of this disclosure, the rechargeable battery includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. 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 and Figure 2 This is a cross-sectional view of a separator for a rechargeable lithium battery according to an example embodiment; and Figures 3 to 6 This is a schematic diagram illustrating 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 provided as examples, and the present disclosure is not limited thereto, and is limited only by the scope of the described claims.

[0016] Unless otherwise stated herein, when a component such as a layer, film, region, plate, etc., is described as being “on” another component, it includes not only the case where the component is “directly on” the other component, but also the case where there is another component in between.

[0017] Unless otherwise stated in this specification, anything indicated in the singular may also include the plural. Furthermore, unless otherwise stated, “A or B” may mean “including A, including B, or including both A and B”.

[0018] As used herein, the term "combination of components" can refer to mixtures, laminates, complexes, copolymers, alloys, blends, and reaction products of components.

[0019] Here, the term "particle size D50" refers to the average particle size, which is the diameter of the particles that constitute 50% of the total volume in the particle size distribution. The particle size distribution can be measured by methods known to those skilled in the art. For example, it can be measured using a particle size analyzer, transmission electron microscopy, or scanning electron microscopy. In another method, the D50 value can be obtained by measuring the 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 from that data. Alternatively, D50 can be measured using laser diffraction. For example, when measured by laser diffraction, after dispersing the particles to be measured in a dispersion medium, the particles can be introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound at approximately 28 kHz at an output of 60 W, and the D50 can be calculated based on the 50% volume particle size distribution in the measuring device.

[0020] In this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0021] Unless otherwise defined herein, “substitution” means that hydrogen in a compound is replaced by a substituent such as or including C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C7 to C30 alkylaryl, C1 to C30 alkoxy, C1 to C30 heteroalkyl, C3 to C30 heteroalkylaryl, C3 to C30 cycloalkyl, C3 to C15 cycloalkenyl, C6 to C30 cycloalkynyl, C2 to C30 heterocycloalkyl, halogen (F, Cl, Br or I), hydroxyl (-OH), nitro (-NO2), cyano (-CN), amino (-NRR') (wherein R and R' are both independently hydrogen or C1 to C6 alkyl), sulfobetaine (-RR'N) + (CH2) n SO3 - n is a natural number ranging from 1 to 10, and R and R' are both independently C1 to C20 alkyl groups, carboxybenzene groups (-RR'N). + (CH2) n COO -The following groups are used: n is a natural number from 1 to 10 (where R and R' are both independently C1 to C20 alkyl groups), at least one of the following groups: azide (-N3), amidine (-C(=NH)NH2), hydrazine (-NHNH2), hydrazone (=N(NH2)), carbamoyl (-C(=O)NH2), thiol (-SH), acyl (-C(=O)R, where R is 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 is an organic or inorganic cation), sulfonic acid (-SO3H) or a salt thereof (-SO3M, where M is an organic or inorganic cation), phosphate (-PO3H2) or a salt thereof (-PO3MH or -PO3M2, where M is an organic or inorganic cation), and combinations thereof.

[0022] In the following text, C1 to C3 alkyl means methyl, ethyl, or propyl. C1 to C10 alkylene can be or include, for example, C1 to C6 alkylene, C1 to C5 alkylene, or C1 to C3 alkylene, such as methylene, ethylene, or propylene. C3 to C20 cycloalkylene can be or include, for example, C3 to C10 cycloalkylene or C5 to C10 cycloalkylene, such as cyclohexylene. C6 to C20 arylene can be or include, for example, C6 to C10 arylene, such as phenylene. C3 to C20 heterocyclic can be or include, for example, C3 to C10 heterocyclic, such as pyridyl.

[0023] In the following text, “heterogeneous” means one or more heteroatoms that include or contain at least one of N, O, S, Si and P.

[0024] In chemical formulas, Symbols indicate parts that are attached to the same or different atoms, groups, or structural units. Unless otherwise specified in the chemical formulas described herein, hydrogen can be considered to be bonded to the structure of the chemical formula.

[0025] 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.

[0026] When describing numerical ranges in this specification, “X to Y” means “X or greater and Y or less (greater than or equal to X and less than or equal to Y)”.

[0027] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it means that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0028] This disclosure is described in detail below. In this description, only rechargeable lithium-ion batteries are described. However, in addition to rechargeable lithium-ion batteries, this disclosure can also be applied to rechargeable batteries using different metal ions.

[0029] Separator for rechargeable lithium batteries: According to one example embodiment, a separator for a rechargeable lithium battery includes a porous substrate and a coating formed on at least one surface of the porous substrate, wherein the coating includes an adhesive layer comprising an adhesive core-shell adhesive having a core and a shell surrounding the core, and the shell having a functional group containing an -SS- group at one end.

[0030] Functional groups containing -SS- group Functional groups containing -SS- groups allow for interconversion of bonds within and between functional groups at high temperatures, thereby improving adhesion retention even when external stress is applied to the separator. Furthermore, functional groups containing -SS- groups can reduce separator resistance, increase lithium-ion dissociation, form ion transport channels, and increase wet adhesion to each of the positive and negative electrodes. Therefore, the separator can increase battery life at both room temperature and high temperatures. Additionally, functional groups containing -SS- groups can undergo metathesis to further increase wet adhesion to each of the positive and negative electrodes and reduce membrane resistance.

[0031] According to one example embodiment, the wet adhesion of the diaphragm to the positive electrode can be about 0.85 gf / mm or greater.

[0032] According to one example embodiment, the wet adhesion of the diaphragm to the negative electrode can be about 0.77 gf / mm or greater.

[0033] According to one example embodiment, the diaphragm may have a membrane resistance of about 0.65 Ω or less.

[0034] In one example, the functional group containing the -SS- group can be or includes adhesive functional groups.

[0035] In one example, a functional group containing the -SS- group can be represented by the following chemical formula 1: Chemical Formula 1: .

[0036] In chemical formula 1, R 11 It is or includes substituted or unsubstituted C1 to C10 alkyl or substituted or unsubstituted C6 to C10 aryl.

[0037] In one example embodiment, R 11It may be or include C1 to C5 alkyl groups substituted with amino groups or C6 to C10 aryl groups substituted with amino groups.

[0038] In one example embodiment, the functional group containing the -SS- group can be -SS-CH2CH2-NH2 or -SS-C6H5-NH2.

[0039] Functional groups containing the -SS- group can be directly bound to the main chain of the shell, or they can be bound to the main chain of the shell through a linker.

[0040] For example, the linker can be represented by one of the following chemical formulas 2-1 to 2-12: Chemical formula 2-1: .

[0041] Chemical formula 2-2: .

[0042] Chemical formula 2-3: .

[0043] Chemical formula 2-4: .

[0044] Chemical formula 2-5: .

[0045] Chemical formula 2-6: .

[0046] Chemical formula 2-7: .

[0047] Chemical formula 2-8: .

[0048] Chemical formula 2-9: .

[0049] Chemical formula 2-10: .

[0050] Chemical formula 2-11: .

[0051] Chemical formula 2-12: .

[0052] In chemical formulas 2-1 to 2-12, Both n and m are integers greater than or equal to 0, and R a R b R c R d and R e Each is independently hydrogen or a substituted or unsubstituted C1 to C10 alkyl group.

[0053] The linker can be attached to the main chain of the shell and the functional group containing the -SS- group by typical methods known to those skilled in the art.

[0054] In one example, the shell may have structural units containing alkylene glycol groups and structural units containing cyano groups, and a functional group containing -SS- groups may be attached to one end of the structural unit containing alkylene glycol groups.

[0055] In this regard, the linker can be incorporated into the structural unit containing an alkylene glycol group using typical methods known to those skilled in the art. For example, the following scheme can be referenced: Reaction scheme 1: .

[0056] Reaction scheme 2: .

[0057] Reaction scheme 3: .

[0058] Reaction scheme 4: .

[0059] Reaction scheme 5: .

[0060] Reaction scheme 6: .

[0061] Reaction scheme 7: .

[0062] Reaction scheme 8: .

[0063] Reaction scheme 9: .

[0064] Reaction scheme 10: .

[0065] Reaction scheme 11: .

[0066] The structural units containing alkylene glycol groups and cyanide groups are described in more detail below.

[0067] Core-shell binder: Core-shell binders can provide low resistance, high lithium-ion dissociation, ion transport channels, and high wet adhesion to each of the positive and negative electrodes.

[0068] According to one example embodiment, the core-shell binder may be or include an aqueous adhesive. Therefore, the core-shell binder can be used in an aqueous solvent (e.g., water) to provide an aqueous coating, thereby allowing the fabrication of an environmentally friendly membrane.

[0069] According to one example embodiment, the core-shell binder may be or include a particulate binder. For example, the average particle size D50 of the particulate core-shell binder may be about 700 nm or less, such as 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, or 700 nm, falling within the range of about 200 nm to about 700 nm, 300 nm to 700 nm, or 300 nm to 600 nm. The core-shell binder may be included in the coating while providing an adhesive effect within the aforementioned ranges.

[0070] The average particle size D50 can be adjusted by controlling the reaction temperature and stirring speed during the preparation of the core-shell binder.

[0071] In the core-shell binder, the amount of core can range from about 40 wt% to about 90 wt% (e.g., 50 wt% to 70 wt%), and the amount of shell can range from about 10 wt% to about 60 wt% (e.g., 30 wt% to 50 wt%). Within the above ranges, the core-shell binder can have high mechanical strength, thereby increasing the strength of the diaphragm and providing the diaphragm's effect.

[0072] The core-shell binder can have a glass transition temperature in the range of about 50°C to about 70°C (e.g., 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, or 70°C). Within this range, the diaphragm incorporating the core-shell binder can be stable at room temperature and can exhibit adhesive properties after high-temperature pressing. The glass transition temperature of the core-shell binder can be achieved by adjusting the content of functional groups containing -SS- groups, the molar ratio of repeating units in the main chain of the shell, etc.

[0073] nuclear The core may be or include an organic core, and may include a first copolymer.

[0074] The first copolymer may be a copolymer of at least one or a combination of aromatic vinyl monomers, diene monomers, (meth)acrylate monomers, ester monomers, olefin monomers and carbamate monomers.

[0075] According to one example embodiment, the first copolymer may be or include a copolymer of at least one or a combination of aromatic vinyl monomers and (meth)acrylate monomers.

[0076] Aromatic vinyl monomers may be or include at least one of styrene, C1 to C10 alkyl-substituted styrene, halogen-substituted styrene, or combinations thereof. C1 to C10 alkyl-substituted styrene may include at least one of ethylstyrene, methylstyrene, etc.

[0077] (Meth)acrylate monomers may be or include (meth)acrylates having substituted or unsubstituted C1 to C10 alkyl groups in the ester moiety.

[0078] According to one example embodiment, the first copolymer may be or include a copolymer of diene monomers and aromatic vinyl monomers. The diene monomers may be or include conjugated diene monomers (such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, or chloroprene) or non-conjugated diene monomers (such as vinylnorbornene, dicyclopentadiene, or 1,4-hexadiene). The aromatic vinyl monomers are as described above.

[0079] According to one example embodiment, the first copolymer may be or include a rubber polymer. For example, the rubber polymer may be or include at least one of butadiene rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylic rubber, acrylonitrile-butadiene rubber, acrylonitrile-butadiene-styrene rubber, isoprene rubber, isobutylene-isoprene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, polyorganosiloxane-poly(meth)acrylate rubber, fluororubber, or combinations thereof.

[0080] The core may include either a cross-linked form of the first copolymer or a non-cross-linked form of the first copolymer.

[0081] shell The shell surrounds the surface of the core, and the shell includes a second copolymer attached to the surface of the core.

[0082] In one example, the second copolymer has alkylene glycol-containing structural units and cyano-containing structural units, and has a -SS- group-containing functional group at one end. The other end of the second copolymer may be bonded to the surface of the core. The alkylene glycol-containing structural units and the cyano-containing structural units may be present between the surface of the core and the -SS- group-containing functional group.

[0083] The structural unit containing alkylene glycol groups can be or includes lithium-ion conducting units, and can form lithium-ion transport channels and reduce the resistance of the separator, thereby improving the battery life at room temperature and high temperature.

[0084] The cyano-containing structural unit can be or includes a lithium-ion conducting unit, and can form a lithium-ion transport channel and reduce the resistance of the separator, thereby improving the battery life at room temperature and high temperature.

[0085] According to one example embodiment, the second copolymer may have alkylene glycol-containing structural units and cyano-containing structural units in the main chain of the second copolymer.

[0086] The structural unit containing an alkylene glycol group can be represented by the following chemical formula 3, and the second copolymer can include one or more structural units of the following chemical formula 3: Chemical formula 3: .

[0087] In chemical formula 3, n is 0 or 1, and R 1 It is a straight-chain or branched substituted or unsubstituted C1 to C10 alkylene group.

[0088] In one example, chemical formula 3 can be a combination of one or more of the following chemical formulas: chemical formula 3-1, chemical formula 3-2, and chemical formula 3-3: Chemical formula 3-1: .

[0089] Chemical formula 3-2: .

[0090] Chemical formula 3-3: .

[0091] In one example, the structural unit containing an alkylene glycol group may be derived from at least one of ethylene glycol, n-propylene glycol, and propylene carbonate. For example, the second copolymer may include units derived from at least one of polyethylene glycol, polypropylene glycol, and polypropylene carbonate.

[0092] Relative to 100 mol% of the repeating unit of the second copolymer, it can be in the range of about 15 mol% to about 85 mol% (15 mol% to 75 mol%, 25 mol% to 85 mol%, 25 mol% to 70 mol%, 30 mol% to 75 mol% or 30 mol% to 70 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%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 4 The amounts of 3 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 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%, 76 mol%, 77 mol%, 78 mol%, 79 mol%, 80 mol%, 81 mol%, 82 mol%, 83 mol%, 84 mol%, and 85 mol%) include structural units containing alkylene glycol groups. When structural units containing alkylene glycol groups are included within the above ranges, the membrane can ensure desired or improved oxidation resistance and can exhibit adhesion, heat resistance, and air permeability.

[0093] The cyano-containing structural unit can be represented by the following chemical formula 4, and the second copolymer can include one or more structural units of the following chemical formula 4: Chemical formula 4: .

[0094] In chemical formula 4, R 3 and R 4 Each is independently hydrogen or a C1 to C3 alkyl group. L 1 It is or includes -C(=O)-, -C(=O)O-, -OC(=O)-, -O-, or -C(=O)NH-, where x is an integer from 0 to 2. L2 It is 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, and y is an integer ranging from 0 to 2.

[0095] The cyano-containing structural unit can be derived from, for example, (meth)acrylonitrile, olefin nitrile, (meth)acrylic acid cyanoalkyl ester, or 2-(ethoxy)alkane nitrile. Here, the olefin can be or includes C2 to C20 olefins, C2 to C10 olefins, or C2 to C6 olefins, and the alkyl can be or includes C1 to C20 alkyl, C1 to C10 alkyl, or C1 to C6 alkyl. Additionally, the alkane can be or includes C1 to C20 alkanes, C1 to C10 alkanes, or C1 to C6 alkanes.

[0096] Olefin nitrile may be or include at least one of, for example, allyl cyanide, 4-pentenonitrile, 3-pentenonitrile, 2-pentenonitrile, or 5-hexenonitrile. (Meth)acrylate cyanoalkyl ester may be or include at least one of, for example, cyanomethyl (meth)acrylate, cyanoethyl (meth)acrylate, cyanopropyl (meth)acrylate, or cyanooctyl (meth)acrylate. 2-(ethoxy)alkane nitrile may be or include, for example, 2-(ethoxy)acetonitrile or 2-(ethoxy)propionitrile.

[0097] Relative to 100 mol% of the repeating units of the second copolymer, it can be in the range of about 15 mol% to about 80 mol% (e.g., 15 mol% to 70 mol%, 25 mol% to 80 mol%, 25 mol% to 65 mol%, 30 mol% to 70 mol%, or 30 mol% to 65 mol%) (e.g., 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%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%). The amounts of cyano-containing structural units (40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 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%, 76 mol%, 77 mol%, 78 mol%, 79 mol%, 80 mol%) include cyano-containing structural units. When cyano-containing structural units are included within the above ranges, the membrane can ensure desired or improved oxidation resistance and can exhibit adhesiveness, heat resistance, and air permeability.

[0098] According to one example embodiment, relative to 100 mol% of the repeating units of the second copolymer, the total amount of alkylene glycol-containing structural units and cyano-containing structural units can be included in an amount of about 95 mol% or greater (e.g., the range from about 95 mol% to about 100 mol%, or 100 mol%). Within the above range, the effects of the membrane described above can be easily achieved.

[0099] The second copolymer may also include structural units derived from (meth)acrylic acid or (meth)acrylate.

[0100] The second copolymer may include structural units derived from (meth)acrylic acid or (meth)acrylate in the main chain of the second copolymer.

[0101] For example, the second copolymer may include structural units derived from (meth)acrylic acid.

[0102] Structural units derived from (meth)acrylic acid or (meth)acrylates can include lithium cations in the unit structure, and thus lithium cations can be provided through the dissociation process of lithium cations. Therefore, the membrane can provide the effect of increasing lithium cation concentration and reducing resistance. Additionally, the membrane can have carboxyl functional groups to further increase adhesion. Furthermore, the membrane can further increase adhesion to ensure high adhesion to the electrode, and can provide desired or improved heat resistance, permeability, and oxidation resistance. Additionally, dispersibility in compositions for coatings including core-shell binders can be improved.

[0103] In structural units derived from (meth)acrylates or (meth)acrylic acid, the (meth)acrylate can be or include a conjugate base of (meth)acrylic acid, a (meth)acrylate salt, or a derivative thereof. Structural units derived from (meth)acrylates or (meth)acrylic acid can be represented, for example, by the following chemical formulas 5, 6, or 7, or combinations thereof: Chemical formula 5: .

[0104] Chemical formula 6: .

[0105] Chemical Formula 7: .

[0106] In chemical formulas 5 to 7 R 5 R 6 R 7 R 8 R 9 and R 10 Each is independently hydrogen or methyl, and in the above chemical formula 6, M is or includes an alkali metal.

[0107] Alkali metals can be, or include, for example, lithium, sodium, potassium, rubidium, or cesium. For example, an alkali metal can be lithium.

[0108] In the repeating units of the second copolymer, the content can be in the range of about 0 mol% to about 70 mol% (e.g., 0.1 mol% to 30 mol%, 0.1 mol% to 25 mol%, 1 mol% to 25 mol%, 1 mol% to 20 mol%, or 5 mol% to 20 mol%) (e.g., 0 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%). The amounts of 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%, 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%, and 70 mol%) include structural units derived from (meth)acrylates or (meth)acrylic acid. When structural units derived from (meth)acrylates or (meth)acrylic acid are included within the above ranges, the membrane can exhibit desired or improved adhesion, heat resistance, air permeability, and oxidation resistance.

[0109] As an example, structural units derived from (meth)acrylates or (meth)acrylic acid may include structural units represented by Chemical Formula 6 above and structural units represented by Chemical Formula 7 above, and in this case, structural units represented by Chemical Formula 6 above and structural units represented by Chemical Formula 7 above may be included in a molar ratio in the range of about 10:1 to about 1:2, 10:1 to 1:1 or 5:1 to 1:1.

[0110] According to one example embodiment, relative to 100 mol% of the repeating units of the second copolymer, the total amount of alkylene glycol-containing structural units, cyano-containing structural units, and structural units derived from (meth)acrylate or (meth)acrylic acid can be included in an amount of about 95 mol% or greater (e.g., the range from about 95 mol% to about 100 mol%, or about 100 mol%). Within the above range, the effects of the aforementioned diaphragm can be readily achieved.

[0111] The second copolymer can be provided in various forms, such as an alternating polymer in which structural units are distributed alternately, an irregular polymer in which structural units are distributed randomly, or a grafted polymer in which some of the structural units are grafted.

[0112] The shell has a functional group containing an -SS- group at one end.

[0113] The shell may include a second copolymer having functional groups containing the same -SS- group at one end, or may include a second copolymer having functional groups containing different types of -SS- groups at one end.

[0114] The second copolymer may have a functional group containing one type of -SS- group at one end, or it may have a functional group containing two or more different types of -SS- groups.

[0115] Functional groups containing -SS- groups can be incorporated into structural units containing alkylene glycol groups, cyano groups, or structural units derived from (meth)acrylates or (meth)acrylic acid.

[0116] In one example, a functional group containing an -SS- group can bind to a structural unit containing an alkylene glycol group. This is the same as described above.

[0117] The core-shell binder may be included in the adhesive layer in an amount of about 50 wt% or more (e.g., in the range of about 50 wt% to about 100 wt%). Within this range, the diaphragm effect can be easily achieved.

[0118] In one example, the second copolymer can be prepared by polymerizing a monomer that provides a cyano-containing structural unit (e.g., a monomer that provides a structural unit of Formula 2 above) and a monomer that provides an alkylene glycol-containing structural unit (e.g., a monomer that provides a structural unit of Formula 1 above), and then introducing adhesive functional groups at the ends.

[0119] In another example embodiment, the second copolymer may be or include a copolymer of monomer mixtures comprising (A) a prepolymer of alkylene glycol-containing structural units having adhesive functional groups at one end, and (B) monomers providing cyano-containing structural units. In this case, a mass ratio can be set such that out of a total of 100 parts by mass, approximately 10 to approximately 90 parts by mass (e.g., 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, 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, 52 parts by weight, etc.). 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 The amount includes (A) in the range of parts by weight, 78 parts by weight, 79 parts by weight, 80 parts by weight, 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, 20 to 80 parts by weight, 30 to 70 parts by weight, or 30 to 50 parts by weight, and is in the range of about 10 parts by weight to about 90 parts by weight (e.g.,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, 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, 52 parts by weight, 53 parts by weight, 54 parts by weight The quantities within the range of (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, 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, 20 to 80 parts by weight, 30 to 70 parts by weight, or 50 to 70 parts by weight) include (B).

[0120] In another example, the second copolymer may be or include a copolymer of monomer mixtures comprising (A) a prepolymer of an alkylene glycol-containing structural unit having an adhesive functional group at one end, (B) a monomer providing a cyano-containing structural unit, and (C) (meth)acrylate or (meth)acrylic acid. In this case, a mass ratio can be set such that out of a total of 100 parts by mass, approximately 10 parts by mass are distributed to approximately 80 parts by mass (e.g., 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, 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, 4...). The amounts included in the range of 7 parts by weight, 48 parts by weight, 49 parts by weight, 50 parts by weight, 51 parts by weight, 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, 20 to 70 parts by weight, 20 to 60 parts by weight, or 20 to 50 parts by weight include (A), to be in the range of about 10 parts by weight to about 80 parts by weight (e.g.,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, 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, 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, 6 The quantities included in (B) are in the range of 8 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, 20 to 70 parts by weight, 30 to 70 parts by weight, or 30 to 60 parts by weight, and are in the range of about 1 part by weight to about 30 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). The quantity within the range of 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, 28 parts by weight, 29 parts by weight, 30 parts by weight, or 5 to 30 parts by weight or 5 to 20 parts by weight includes (C).

[0121] The adhesive layer may also include a linear adhesive.

[0122] Linear adhesives may or may not have functional groups containing -SS- groups at one or both ends of the main chain of the linear adhesive.

[0123] In one example embodiment, the core-shell binder and the linear binder may have functional groups containing the same -SS- group. The functional groups at the ends containing the same -SS- group can interact with each other to increase the bonding strength between the core-shell binder and the linear binder, thereby increasing the wet adhesion of the coating to each of the positive and negative electrodes.

[0124] Functional groups containing -SS- groups can be represented by the above chemical formula 1.

[0125] According to one example embodiment, linear adhesives can relatively easily fill empty spaces in the coating compared to core-shell adhesives. Specifically, when the coating includes fillers as described below, linear adhesives can easily fill the empty spaces between the fillers. Therefore, the diaphragm can have high adhesion between the coating and the porous substrate. Additionally, when the coating includes a heat-resistant layer containing fillers as described below and an adhesive layer located on the heat-resistant layer, the diaphragm can provide high adhesion between the heat-resistant layer and the adhesive layer.

[0126] Linear adhesives can significantly increase wet adhesion to each of the positive and negative electrodes through interaction with core-shell adhesives, and can also increase the adhesion between the porous substrate, the heat-resistant layer, and the adhesive layer.

[0127] Linear adhesives can be or include water-based adhesives.

[0128] Linear binders may have a weight-average molecular weight in the range of about 500 g / mol to about 50,000 g / mol (e.g., 500 g / mol, 1000 g / mol, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, 5000 g / mol, 5500 g / mol, 6000 g / mol, 6500 g / mol, 7000 g / mol, 7500 g / mol, 8000 g / mol, 8500 g / mol, 9000 g / mol, 10000 g / mol, 20000 g / mol, 30000 g / mol, 40000 g / mol, 50000 g / mol, 1000 g / mol to 5000 g / mol). Within the above range, the empty spaces between fillers or the spaces between core-shell binders can be easily filled.

[0129] When a linear adhesive has a functional group containing a -SS- group at its end, there are no particular restrictions on the structural units included in the main chain of the adhesive.

[0130] According to one example embodiment, the backbone of the shell of the core-shell adhesive may be the same as or different from the backbone of the linear adhesive.

[0131] The main chain of a linear adhesive can be either straight or branched.

[0132] In one example embodiment, the main chain of the linear adhesive may include -O- , -BY 1 - , -NY 2 - , -(C=O)- , -C≡N、 -S- and -(O=S=O)- At least one or a combination thereof. Here, Y 1 and Y 2 They can all be hydrogen or substituted or unsubstituted C1 to C10 alkyl groups independently.

[0133] In one example, the backbone of the linear binder may have at least one of the following: alkylene glycol-containing structural units, cyano-containing structural units, and structural units derived from (meth)acrylate or (meth)acrylic acid.

[0134] For example, the backbone of a linear binder may have structural units containing alkylene glycol groups. These alkylene glycol-containing structural units are the same as those described in Formula 3 above and in Formulas 3-1 to 3-3 above.

[0135] In linear binders, functional groups containing -SS- groups can be directly attached to structural units containing alkylene glycol groups.

[0136] In linear binders, functional groups containing -SS- groups can be linked to structural units containing alkylene glycol groups via linker groups.

[0137] For example, the linker may be or include a functional group having at least one of carbon, oxygen, nitrogen and sulfur in the main chain.

[0138] The linker can be substantially the same as those described in Chemical Formulas 2-1 to 2-12 above.

[0139] For the method of incorporating the linker into the structural unit containing the alkylene glycol group, refer to reaction schemes 1 to 11 above.

[0140] In one example embodiment, the linear binder may have a structure represented by one of the following chemical formulas I, II, and III: Chemical Formula I: R 11 -SSY 1 -XY 2 -SSR 11 .

[0141] In chemical formula I, X is or includes one or a combination of structural units of chemical formula 3. Y 1 and Y 2 All of them are or include one or a combination of chemical formulas 2-1 to 2-12 above, and R 11 It is or includes substituted or unsubstituted C1 to C10 alkyl or substituted or unsubstituted C6 to C10 aryl.

[0142] Chemical Formula II: Y 3 -XY 1 -SSR 11 .

[0143] In chemical formula II, X is or includes one or a combination of structural units of chemical formula 3 above. Y 1 It is or includes one or a combination of chemical formulas 2-1 to 2-12 above. Y 3 It is hydrogen, hydroxyl, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 alkoxy, or substituted or unsubstituted C6 to C10 aryl, and R 11 It is or includes substituted or unsubstituted C1 to C10 alkyl or substituted or unsubstituted C6 to C10 aryl.

[0144] In one example embodiment, R 11 It may be or include C1 to C5 alkyl groups substituted with amino groups or C6 to C10 aryl groups substituted with amino groups.

[0145] In one example, -SSR 11 It may include or can include -SS-CH2CH2-NH2 or -SS-C6H5-NH2.

[0146] Chemical Formula III: Y 3 -XY 4 .

[0147] In chemical formula III, X is or includes one or a combination of structural units of the above chemical formula 3, and Y 3 and Y 4 Each of them is independently hydrogen, hydroxyl, substituted or unsubstituted C1 to C10 alkyl, substituted or unsubstituted C1 to C10 alkoxy or substituted or unsubstituted C6 to C10 aryl.

[0148] In the adhesive layer, core-shell binders and linear binders may be included in a weight ratio ranging from about 2:1 to about 20:1 (e.g., 5:1 to 15:1) (e.g., 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1). Within the above range, an effect of improving the wet adhesion force to each of the positive and negative electrodes can be expected or improved.

[0149] In addition to core-shell adhesives and linear adhesives, the adhesive layer may also include an adhesive bonding agent. For example, an adhesive bonding agent may include at least one of acrylate compounds or derivatives thereof, diallyl phthalate compounds or derivatives thereof, polyimide compounds or derivatives thereof, or polyurethane compounds or derivatives thereof.

[0150] For example, an adhesive could be cross-linked polymethyl methacrylate.

[0151] Heat-resistant layer: The coating may also include a heat-resistant layer.

[0152] In one example, the coating may include a heat-resistant layer and an adhesive layer formed (e.g., formed sequentially) on one or both surfaces of a porous substrate.

[0153] The heat-resistant layer may include a heat-resistant adhesive. The heat-resistant adhesive may be or include a non-core-shell adhesive and may not include a core-shell adhesive.

[0154] Heat-resistant adhesives may include (meth)acrylic adhesives comprising structural units containing sulfonic acid groups. (Methacrylamide) adhesives may also include at least one of structural units derived from (meth)acrylates or (meth)acrylic acid, cyano-containing structural units, and structural units derived from (meth)acrylamide.

[0155] The heat-resistant adhesive may be included in the coating in an amount ranging from about 1 wt% to about 25 wt% (e.g., 1 wt% to 20 wt%, 1 wt% to 15 wt%, or 2 wt% to 15 wt%).

[0156] The heat-resistant layer may also include fillers.

[0157] The filler may have a particle size D50 of about 0.4 μm or less (e.g., 0.35 μm or less, 0.3 μm or less, or in the range of about 0.1 μm to about 0.3 μm). Within the above range, it may have the effect of improving heat resistance.

[0158] The surface of the filler may or may not be modified.

[0159] The filler may be or include, for example, inorganic fillers, organic fillers, organic-inorganic composite fillers, or combinations thereof. Inorganic fillers may include ceramic materials capable of improving heat resistance. Inorganic fillers may include at least one of, for example, metal oxides, quasi-metal oxides, metal fluorides, metal hydroxides, or combinations thereof. Inorganic fillers may include at least one of, for example, Al₂O₃, SiO₂, TiO₂, SnO₂, CeO₂, MgO, NiO, CaO, GaO, ZnO, ZrO₂, Y₂O₃, SrTiO₃, BaTiO₃, Mg(OH)₂, boehmite, or combinations thereof, but this disclosure is not limited thereto. Organic fillers may include at least one of, acrylic compounds, imide compounds, amide compounds, or combinations thereof, but this disclosure is not limited thereto. Organic fillers may have a core-shell structure, but this disclosure is not limited thereto. For example, the filler may include boehmite.

[0160] The filler can be spherical, plate-shaped, cubic, or amorphous. Preferably, the filler can be cubic in shape, and cubic filler can have a significantly lower shrinkage rate.

[0161] The filler should be included in an appropriate amount relative to the heat-resistant binder. According to one example embodiment, the heat-resistant binder and filler can be included in a mass ratio ranging from about 1:10 to about 1:50 (e.g., a mass ratio of 1:20 to 1:30). Within the above range, it can have the effect of improving the heat resistance in the electrolyte.

[0162] In the heat-resistant layer, fillers may be included in an amount ranging from about 50 wt% to about 99 wt% (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%, or 95 wt% to 99 wt%). When fillers are included within the above range, desired or improved heat resistance, durability, oxidation resistance, and stability may be exhibited.

[0163] According to one example embodiment, the coating may include a heat-resistant layer and an adhesive layer, the heat-resistant layer comprising a heat-resistant adhesive and fillers, and the adhesive layer situated on the heat-resistant layer and comprising a core-shell adhesive and optionally a linear adhesive. The heat-resistant layer may be formed from or comprise a composition containing a heat-resistant adhesive and fillers.

[0164] The heat-resistant layer may have a thickness ranging from about 0.01 μm to about 20 μm, and within this range, it may have a thickness of 1 μm to 10 μm, 1 μm to 5 μm, or 1 μm to 3 μm.

[0165] The adhesive layer may have a thickness ranging from about 0.01 μm to about 20 μm, and within the above range, it may have a thickness of 0.1 μm to 10 μm, 0.1 μm to 5 μm, or 0.1 μm to 1 μm.

[0166] The coating is located on at least one surface of the porous substrate.

[0167] The ratio of the coating thickness to the porous substrate thickness can be in the range of about 0.05 to about 0.5 (e.g., 0.05 to 0.4, 0.05 to 0.3, or 0.1 to 0.2). Within this range, the diaphragm can exhibit desired or improved permeability, heat resistance, and adhesion. Here, "coating thickness" refers to the thickness of one coating when the coating is formed on only one surface of the porous substrate, and the total thickness of the two coatings when the coating is formed on both surfaces of the porous substrate.

[0168] porous substrate Porous substrates may be or include substrates having multiple pores and are typically used in electrochemical devices. Not limited thereto, porous substrates may be or include polymer membranes formed or comprising any one of the following polymers or copolymers or mixtures of two or more of them, such polymers being or including at least one of polyolefins (such as polyethylene or polypropylene), polyesters (such as 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, and polytetrafluoroethylene (e.g., Teflon).

[0169] The porous substrate can be or include, for example, a polyolefin substrate comprising polyolefins, and the polyolefin substrate can have a desired or improved shut-off function, thus contributing to improved battery safety. The polyolefin substrate can be or include at least one of, for example, polyethylene monolayer film, polypropylene monolayer film, polyethylene / polypropylene bilayer film, polypropylene / polyethylene / polypropylene trilayer film, and polyethylene / polypropylene / polyethylene trilayer film. Additionally, besides olefin resins, the porous substrate can also include non-olefin resins, or can include copolymers of olefin monomers and non-olefin monomers.

[0170] The porous substrate 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).

[0171] A separator for a rechargeable lithium battery according to an example embodiment of this disclosure can exhibit desired or improved air permeability and can have an air permeability value of, for example, less than about 200 seconds / 100cc, or, for example, 190 seconds / 100cc or less, or 180 seconds / 100cc or less. That is, the separator has an air permeability value of less than about 40 seconds / 100cc per μm of thickness (e.g., 30 seconds / 100cc or less per μm of thickness, or 25 seconds / 100cc or less per μm of thickness). Here, air permeability refers to the time (in seconds) required for 100cc of air to pass through a unit thickness of the separator. Air permeability per unit thickness can be obtained by measuring the air permeability over the entire thickness of the separator and dividing the measured air permeability by the thickness. Air permeability can be measured by measuring the time (in seconds) required for 100cc of air to pass through the separator using a measuring device (EG01-55-1MR manufactured by Asahi Seiko).

[0172] A separator for a rechargeable battery according to an example embodiment can be formed by coating one or both surfaces of a porous substrate with a composition for forming a coating, drying the composition, and then curing the composition. Curing can be performed using typical methods known to those skilled in the art.

[0173] Figure 1 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to an example embodiment.

[0174] Reference Figure 1 The separator for a rechargeable lithium battery includes a porous substrate 1 and a coating 2 located on each of two surfaces of the porous substrate 1. The coating 2 is a laminate of a heat-resistant layer 5 and an adhesive layer 7. The heat-resistant layer 5 may include a filler 3 and a heat-resistant adhesive 4. The adhesive layer 7 may be located on the heat-resistant layer 5 and may include an adhesive core-shell adhesive 6 and a linear adhesive 8.

[0175] Figure 2 This is a cross-sectional view showing a separator for a rechargeable lithium battery according to another example embodiment.

[0176] Reference Figure 2 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, heat-resistant adhesive 4, adhesive core-shell adhesive 6, and linear adhesive 8.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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 metal composite oxides may be used, wherein the metal is, or includes, at least one of cobalt, manganese, nickel, and combinations thereof.

[0181] 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.

[0182] 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 L1 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).

[0183] In the above chemical formulas, 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.

[0184] 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 of 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.

[0185] 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%.

[0186] The binder causes the positive electrode active material particles to adhere to each other and also causes the positive electrode active material to adhere 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 containing 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.

[0187] Conductive materials can impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in batteries. 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, in the form of metal powders or metal fibers, comprising at least one of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0188] Al can be used as a current collector, but current collectors are not limited to this.

[0189] 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).

[0190] For example, the negative electrode active material layer may include a negative electrode active material ranging from about 90 wt% to about 99 wt%, a binder ranging from about 0.5 wt% to about 5 wt%, and a conductive material ranging from about 0 wt% to about 5 wt%.

[0191] Negative electrode active material The negative electrode active material may include at least one of the following: a material that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0192] Materials capable of reversibly inserting / extracting 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 graphite, such as natural graphite or artificial graphite in an irregular shape, 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.

[0193] 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.

[0194] Materials capable of doping / dedoping 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 (excluding 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, or combinations thereof.

[0195] 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) assembled from primary silicon particles and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be between the primary silicon particles, and for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0196] 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 on the surface of the core.

[0197] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used in combination with carbonaceous negative electrode active materials.

[0198] The binder may adhere the negative electrode active material particles to each other and may also adhere the negative electrode active material to the current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0199] 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.

[0200] The waterborne adhesive may be or include at least one of the following: 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.

[0201] When an aqueous binder is used as the negative electrode binder, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may include at least one of Na, K, or Li.

[0202] Dry adhesives can be or include fibrous polymeric materials. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0203] Conductive materials can impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used 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, in the form of metal powders or metal fibers, including at least one of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0204] 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.

[0205] Rechargeable lithium batteries may also include an electrolyte.

[0206] electrolyte Electrolytes used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0207] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0208] 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.

[0209] 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).

[0210] 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.

[0211] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include 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 includes double bonds, aromatic rings, or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0212] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0213] For example, 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.

[0214] Lithium salts dissolved in organic solvents supply lithium ions in batteries, enabling rechargeable lithium batteries to operate and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1At 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).

[0215] Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch, or coin-shaped batteries.

[0216] Figures 3 to 6 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 3 A cylindrical battery is shown. Figure 4 A prismatic battery is shown. Figure 5 and Figure 6 A pouch-type battery is shown. (See reference) Figures 3 to 6 The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode assembly 40 is housed within the housing 50. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 3 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. Figure 4 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative electrode terminal 22 connected to the negative electrode lead connector 21. For example... Figure 5 and Figure 6 As shown, the rechargeable lithium battery 100 may include Figure 6 The electrode terminal 70 shown, or for example Figure 5 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.

[0217] 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.

[0218] 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.

[0219] Example 1 (1) Preparation of core-shell binder 800 mL of distilled water, 40 g of seed kernels (a copolymer of styrene and acrylate (methyl methacrylate)) powder, and 0.8 g of sodium dodecyl sulfate were added to a 3 L flask equipped with a stirrer, thermometer, and condenser, and the air inside the flask was purged with nitrogen. A solution containing the seed kernels was then prepared by stirring while heating the flask to 80 °C.

[0220] In addition, 41.7 g of divinylbenzene, 59.9 g of acrylonitrile, 50 g of sodium dodecyl sulfate, and 1,000 mL of distilled water were sequentially added to a 2 L beaker, and the mixture was then sonicated for 10 minutes at room temperature to prepare a preemulsion. After adding 14 mL of 3 wt% potassium persulfate to the preemulsion solution, the mixture was slowly and continuously added to the seed dispersion over 1.5 hours. The reaction was then maintained for 2 hours for polymerization to prepare the first solution.

[0221] In addition, 23.4 g of polyethylene glycol (maleimide-polyethylene glycol-SS-CH2CH2-NH2 (MAL-PEG-SS-CH2CH2-NH2) manufactured by CDBioparticles), 7.5 g of potassium persulfate, and 200 mL of distilled water were sequentially added to a 500 mL beaker and mixed at room temperature for 10 minutes. This mixture was then added to the first solution, and the reaction was maintained at room temperature for 24 hours to prepare a core-shell binder having a shell of chemical formula 8 below. The prepared core-shell binder was a particulate binder with an average particle size D50 of 500 nm and a glass transition temperature (Tg) of 66.2 °C.

[0222] Chemical formula 8: .

[0223] x and y are the number of moles in each unit.

[0224] (2) Manufacturing of the diaphragm An acrylic binder (10 wt% in distilled water) and boehmite (particle size D50: 0.2 μm, cubic) as filler were mixed at a mass ratio of 1:20 (acrylic binder: filler) based on solid content, added to an aqueous solvent, and ground and dispersed using a bead mill at 25°C for 30 minutes to prepare a dispersion.

[0225] Poly(acrylic acid-co-lithium acrylate-co-acrylamide-co-2-acrylamido-2-methylpropanesulfonate) with a molar ratio of acrylic acid + lithium acrylate, acrylamide and lithium 2-acrylamido-2-methylpropanesulfonate of 10:85:5 is used as an acrylic binder.

[0226] The dispersion was coated onto each of the two surfaces of a porous polyethylene fabric (12 μm thick, 120 sec / 100 cc breathability) to a thickness of up to 1.5 μm using a molding method, and then dried and aged in an oven at 80°C for 16 hours to form a heat-resistant layer.

[0227] The coating solution was prepared by mixing 90 parts by weight of deionized (DI) water and 10 parts by weight of the prepared core-shell binder.

[0228] The coating solution is applied to each of the two surfaces of the heat-resistant layer to a thickness of up to 0.5 μm using a bar coating method, and then stored in an oven at 50°C for 1 hour to form an adhesive layer, thereby manufacturing a separator for rechargeable lithium batteries.

[0229] Example 2 Except as in Example 1, when preparing the core-shell binder, the ratio of acrylonitrile to polyethylene glycol with adhesive functional groups at one end is changed in the total amount of acrylonitrile and polyethylene glycol with adhesive functional groups at one end, as shown in Table 1 below, the membrane is manufactured in the same manner as in Example 1.

[0230] Example 3 800 mL of distilled water, 40 g of seed kernels (a copolymer of styrene and acrylate) powder, and 0.8 g of sodium dodecyl sulfate were added to a 3 L flask equipped with a stirrer, thermometer, and condenser, and the air inside the flask was purged with nitrogen. A solution containing the seed kernels was then prepared by stirring while heating the flask to 80 °C.

[0231] Separately, 41.7 g of divinylbenzene, 44.2 g of acrylonitrile, 17.0 g of lithium acrylate, 50 g of sodium dodecyl sulfate, and 1,000 mL of distilled water were sequentially added to a 2 L beaker, and the mixture was then sonicated at room temperature for 10 minutes to prepare a pre-emulsion. After adding 14 mL of 3 wt% potassium persulfate to the pre-emulsion solution, the mixture was slowly and continuously added to the seed dispersion over 1.5 hours. The reaction was then maintained for 2 hours for polymerization to prepare the first solution.

[0232] In addition, 22.1 g of polyethylene glycol (MAL-PEG-SS-CH2CH2-NH2) with adhesive functional groups at one end, 7.5 g of potassium persulfate, and 200 mL of distilled water were sequentially added to a 500 mL beaker and mixed at room temperature for 10 minutes, then added to the first solution. The reaction was maintained for 24 hours to prepare a core-shell binder having a shell with the following chemical formula 9. The prepared core-shell binder was a particulate binder with an average particle size D50 of 500 nm and a Tg of 65.9 °C.

[0233] Chemical formula 9: .

[0234] x, y, and z are the number of moles in each unit.

[0235] Except for using the prepared core-shell binder, the diaphragm is manufactured in the same manner as in Example 1.

[0236] Example 4 Except as in Example 3, when preparing the core-shell binder, the ratio of acrylonitrile, polyethylene glycol with adhesive functional groups at one end, and lithium acrylate in the total amount of acrylonitrile, polyethylene glycol with adhesive functional groups at one end, and lithium acrylate is changed as shown in Table 1 below, the membrane is manufactured in the same manner as in Example 3.

[0237] Example 5 (1) Preparation of core-shell binder The core-shell binder was prepared in the same manner as in Example 1.

[0238] (2) Preparation of linear binder I The synthesis of linear binder I was carried out under a nitrogen atmosphere. 40 g of HOOC-CH2O-polyethylene glycol (PEG)-CH2-COOH (COOH-CH2O-(PEG)-CH2-COOH) (18.8 mmol) was dissolved in 1 L of dichloromethane (DCM) in a 3 L flask equipped with a stirrer, thermometer, and condenser. Then, 4.64 g of N,N'-dicyclohexylcarbodiimide (DCC, 22.56 mmol) and 2.6 g of N-hydroxysuccinimide (NHS, 22.56 mmol) were added at room temperature, followed by stirring for 12 hours. This solution was then slowly and continuously added to a solution of 28.64 g of cystamine (0.19 mol) dissolved in 200 mL of DCM in a 5 L flask, followed by stirring for 24 hours. The resulting mixture was cooled to 0 °C and then filtered to separate the precipitate. The filtrate was evaporated under vacuum, and the remaining residue was dissolved in 400 mL of DMSO. Impurities were then removed by dialysis in distilled water. Linear binder I was obtained by freeze-drying to remove residual water. Linear binder I is represented by the following chemical formula 10.

[0239] Linear adhesive I includes the components in chemical formula 8 above. .

[0240] Chemical Formula 10: .

[0241] n is the number of times each unit is repeated.

[0242] (3) Manufacturing of the diaphragm Acrylic binder (10 wt% in distilled water) and boehmite (particle size D50: 0.2 μm, cubic type) as filler were mixed at a mass ratio of 1:20 (acrylic binder: filler) based on solid content, added to an aqueous solvent, and ground and dispersed using a bead mill at 25°C for 30 minutes to prepare a dispersion.

[0243] Poly(acrylic acid-co-lithium acrylate-co-acrylamide-co-2-acrylamido-2-methylpropanesulfonate) with a molar ratio of acrylic acid + lithium acrylate, acrylamide and lithium 2-acrylamido-2-methylpropanesulfonate of 10:85:5 is used as an acrylic binder.

[0244] The dispersion was coated onto each of the two surfaces of a porous polyethylene fabric (12 μm thick, 120 sec / 100 cc breathability) to a thickness of up to 1.5 μm using a molding method, and then dried and aged in an oven at 80°C for 16 hours to form a heat-resistant layer.

[0245] The coating solution was prepared by mixing 90 parts by weight of DI water, 9 parts by weight of the prepared core-shell binder, and 1 part by weight of the prepared linear binder I.

[0246] The coating solution is applied to each of the two surfaces of the heat-resistant layer to a thickness of up to 0.5 μm using a bar coating method, and then stored in an oven at 50°C for 1 hour to form an adhesive layer, thereby manufacturing a separator for rechargeable lithium batteries.

[0247] Example 6 The entire process of synthesizing linear binder II was carried out under a nitrogen atmosphere.

[0248] 40g of mPEG-COOH (H3C-(OCH2CH2)) n -COOH (20 mmol) was dissolved in 1 L of DCM in a 3 L flask equipped with a stirrer, thermometer, and condenser. Then, 5 g of DCC (23.5 mmol) and 2.75 g of NHS (23.5 mmol) were added at room temperature, and the mixture was stirred for 5 hours. Next, this solution was slowly and continuously added to a solution of 47.5 g of cystamine (0.19 mol) dissolved in 1 L of DCM in a 5 L flask, and the mixture was stirred for 24 hours. The resulting mixture was cooled to 0 °C and then filtered to separate the precipitate. The filtrate was evaporated under vacuum, and the remaining residue was dissolved in 400 mL of DMSO and then dialyzed in distilled water to remove impurities. Linear binder II could be obtained by freeze-drying to remove the remaining water. Linear binder II is represented by the following chemical formula 11.

[0249] Chemical Formula 11: .

[0250] n is the number of times each unit is repeated.

[0251] Except for using the prepared linear binder II, the diaphragm is manufactured in the same manner as in Example 5.

[0252] Example 7 (1) Preparation of core-shell binder The core-shell binder was prepared in the same manner as in Example 1.

[0253] (2) Manufacturing of the diaphragm In addition to using polyethylene glycol dimethyl ester (H3CO-PEG-CH3, M) in Example 5, n =2,000)(Linear binder III) is used as an alternative to linear binder to manufacture the diaphragm in the same manner as in Example 5.

[0254] Comparison Example 1 Except as in Example 1, where polyethylene glycol without adhesive functional groups at one end is used instead of polyethylene glycol with adhesive functional groups at one end to produce a core-shell adhesive having a shell without adhesive functional groups at the end, the diaphragm is manufactured in the same manner as in Example 1.

[0255] Comparison Example 2 Except that, in Example 3, polyethylene glycol with adhesive functional groups at one end is not used, and a core-shell adhesive having a shell having structural units derived from acrylonitrile and lithium acrylate is used, the diaphragm is manufactured in the same manner as in Example 3.

[0256] Compare Example 3 Except that, in Example 3, polyethylene glycol without adhesive functional groups at one end is used instead of polyethylene glycol with adhesive functional groups at one end, and a core-shell adhesive with a shell without adhesive functional groups at the end is used, the diaphragm is manufactured in the same manner as in Example 3.

[0257] Compare Example 4 Except that, in Example 3, acrylonitrile is not used, and polyethylene glycol without adhesive functional groups at one end is used instead of polyethylene glycol with adhesive functional groups at one end, and a core-shell adhesive having a shell having units derived from polyethylene glycol and lithium acrylate is used, the diaphragm is manufactured in the same manner as in Example 3.

[0258] Compare Example 5 In addition to using polyethylene glycol without adhesive functional groups at one end as the core-shell adhesive in Example 5, the membrane is manufactured in the same manner as in Example 5, except that a core-shell adhesive having a shell without adhesive functional groups at one end is used instead of polyethylene glycol with adhesive functional groups at one end.

[0259] The physical properties listed in Table 1 below are evaluated for the diaphragms manufactured according to the example and comparative examples.

[0260] (1) Air permeability (unit: seconds / 100°C) For the diaphragms manufactured in the example and comparative examples, air permeability was measured by measuring the time (in seconds) required for 100cc of air to pass through the diaphragm using a measuring device (EG01-55-1MR manufactured by Asahi Seiko). The air permeability was measured twice to obtain an average value.

[0261] Air permeability measurement equipment setting conditions: Measured pressure: 0.5 kg / cm² 2 Cylinder pressure: 2.5 kg / cm² 2 Set time: 10 seconds.

[0262] (2) Wet adhesion force to the positive electrode and wet adhesion force to the negative electrode (unit: gf / mm) The separators for rechargeable lithium batteries in each example and comparative example were cut into 3cm × 8cm dimensions to prepare samples.

[0263] A positive electrode slurry was prepared by mixing 97 wt% LiCoNiAl as the positive electrode active material, 1.5 wt% carbon nanotubes as the conductive material, and 1.5 wt% polyvinyl fluoride and adding water.

[0264] The prepared positive electrode slurry is coated onto aluminum foil, dried, and rolled to manufacture the positive electrode.

[0265] A negative electrode slurry was prepared by mixing 97.4 wt% of graphite (a negative electrode active material), 1.0 wt% of carboxymethyl cellulose, 1.5 wt% of styrene-butadiene rubber, and 0.1 wt% of carbon nanotubes as a conductive material. The prepared negative electrode slurry was coated with copper foil, dried, and rolled to manufacture the negative electrode.

[0266] The diaphragm was adhered between the positive electrodes and then inserted into the bag. The electrolyte (1.3 M LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC) / methyl ethyl carbonate (EMC) / diethyl carbonate (DEC) at a volume ratio of 3 / 5 / 2) was injected into the bag and left to stand for 12 hours. Then, the solution was applied at 10 kgf / cm³. 2 Up to 20 kgf / cm 2 The bag was pressed under conditions ranging from a pressure within a certain range, a temperature within a range of 70°C to 90°C, and a duration within a range of 5 to 20 seconds, and then disassembled. The diaphragm and positive electrode were removed from the bag, and the diaphragm was separated from the positive electrode plate by a range of approximately 10 mm to approximately 20 mm. Then, the positive electrode and diaphragm were pulled and peeled off in opposite directions at an angle of 180°. The peeling speed was 100 mm / min, and the required force was measured three times in the 20 mm to 40 mm range after the start of peeling, and the average value was obtained. The average value was calculated as the average of the measured values.

[0267] The diaphragm was adhered between the negative electrodes and then inserted into the bag. The electrolyte (1.3 M LiPF6 dissolved in a mixed solvent with a volume ratio of 3 / 5 / 2 EC / EMC / DEC) was injected into the bag and left for 12 hours. Then, the bag was subjected to a pressure of 10 kgf / cm². 2 Up to 20 kgf / cm 2The bag was pressed under conditions ranging from 70°C to 90°C and from 5 to 20 seconds, and then disassembled. The diaphragm and negative electrode were removed from the bag, and the diaphragm was separated from the negative electrode plate by approximately 10 mm to approximately 20 mm. The negative electrode and diaphragm were then pulled and peeled off in opposite directions at an angle of 180°. The peeling speed was 100 mm / min, and the required force was measured three times in the 20 mm to 40 mm interval after the start of peeling, and the average value was obtained. The average value was calculated as the average of the measured values.

[0268] (3) EIS resistance of the diaphragm (unit: Ω) A coin cell for resistance measurement was fabricated using a separator and electrolyte (1.3M LiPF6 dissolved in a mixed solvent of EC / EMC / DEC in a volume ratio of 3 / 5 / 2). After stacking two separator sheets and cutting them into circles with a diameter of 19 mm, the separator was placed on a housing, a gasket was placed on the separator, and 10 drops of electrolyte were applied. A 1 mm thick spacer was placed on the separator. Next, a spring was placed on the resulting material to reduce or prevent gaps between the upper and lower ends inside the CR2032 coin cell, and the CR2032 coin cell was covered with a cap and sealed using a special clamp. CR2032 material manufactured by Hohsen was used when fabricating the CR2032 coin cell. The resistance Y of the coin cell was measured using electrochemical impedance spectroscopy (EIS).

[0269] Table 1:

[0270] Thickness: When the heat-resistant layer and the adhesive layer are each formed on each of the two surfaces of the porous substrate, only the thickness of one layer is described.

[0271] As shown in Table 1 above, the example separator for rechargeable lithium batteries exhibits significantly high wet adhesion and low resistance to each of the positive and negative electrodes.

[0272] However, as shown in Table 1 above, compared with the example, the diaphragm of the comparative example does not have a good effect on the wet adhesion and resistance of each of the positive and negative electrodes.

[0273] The separator for a rechargeable lithium battery according to an example embodiment has significantly high wet adhesion to each of the positive and negative electrodes, and also high wet adhesion between the porous substrate, the heat-resistant layer, and the adhesive layer. The separator for a rechargeable lithium battery according to an example embodiment can have low resistance, can increase the degree of lithium-ion dissociation, can form ion transport channels, and can increase battery life at both room temperature and high temperature.

[0274] 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 present disclosure, and the accompanying drawings, and such modifications also fall within the scope of the present disclosure.

Claims

1. A separator for a rechargeable battery, the separator comprising: porous substrate; as well as A coating is formed on at least one surface of the porous substrate. The coating includes an adhesive layer. The adhesive layer comprises an adhesive core-shell adhesive having a core and a shell surrounding the core, and The shell includes a functional group containing a -SS- group, which is located at one end of the shell.

2. The septum of claim 1, wherein, The functional group containing the -SS- group is represented by chemical formula 1: Chemical Formula 1: ； in: R 11 comprises a substituted or unsubstituted C1to C10alkyl group or a substituted or unsubstituted C6to C10aryl group.

3. The septum of claim 2, wherein, R 11 comprises a Ci to C5 alkyl group substituted with an amine group or a C6 to C10 aryl group substituted with an amine group.

4. The septum of claim 1, wherein, The functional groups containing -S-S- groups include -S-S-CH2CH2-NH2, and -S-S-C6H5-NH2.

5. The diaphragm according to claim 1, wherein, The functional group containing the -SS- group is directly bonded to the main chain of the shell or is bonded to the main chain of the shell through a linker.

6. The septum of claim 5, wherein, The linker is represented by any one of chemical formulas 2-1 to 2-12: Chemical formula 2-1: ； Chemical formula 2-2: ； Chemical formula 2-3: ； Chemical formula 2-4: ； Chemical formula 2-5: ； Chemical formula 2-6: ； Chemical formula 2-7: ； Chemical formula 2-8: ； Chemical formula 2-9: ； Chemical formula 2-10: ； Chemical formula 2-11: ； Chemical formula 2-12: ； in: Both n and m are integers greater than or equal to 0, and R a , R b , R c , R d , and R e are each independently hydrogen or substituted or unsubstituted Ci to C10 alkyl.

7. The septum of claim 1, wherein, The shell comprises a second copolymer; In 100 mol% of repeating units of the second copolymer, alkylene glycol-containing structural units are included in an amount ranging from 15 mol% to 85 mol%, and cyano-containing structural units are included in an amount ranging from 15 mol% to 80 mol%. The functional group containing the -SS- group is attached to one end of the structural unit containing the alkylene glycol group.

8. The septum of claim 1, wherein, The shell comprises a second copolymer; In 100 mol% of repeating units of the second copolymer, alkylene glycol-containing structural units are included in an amount ranging from 15 mol% to 85 mol%, cyano-containing structural units are included in an amount ranging from 15 mol% to 80 mol%, and structural units derived from (meth)acrylic acid or (meth)acrylates are included in an amount greater than 0 mol% and less than or equal to 70 mol%. The functional group containing the -SS- group is attached to one end of the structural unit containing the alkylene glycol group.

9. The septum of claim 1, wherein, The shell has one or more combinations of chemical formulas 8 and 9: Chemical formula 8: ； Chemical formula 9: ； Where x, y, and z are the number of moles in each unit.

10. The septum of claim 1, wherein, The core-shell binder has a glass transition temperature in the range of 50°C to 70°C.

11. The septum of claim 1, wherein, The core-shell binder is a particulate, water-based binder with an average particle size of 700 nm or less.

12. The septum of claim 1, wherein, The core-shell adhesive is included in the adhesive layer in an amount of 50 wt% or greater.

13. The septum of claim 1, wherein, The adhesive layer also includes a linear adhesive.

14. The septum of claim 13, wherein, The linear binder has or does not have a functional group containing -SS- at one or both ends of the main chain of the linear binder.

15. The septum of claim 14, wherein, The functional group containing the -SS- group in the linear binder is represented by the following chemical formula 1: Chemical Formula 1: ； in: R 11 comprises a substituted or unsubstituted C1to C10alkyl group or a substituted or unsubstituted C6to C10aryl group.

16. The septum of claim 14, wherein, The functional groups containing -SS- groups in the linear adhesive include -SS-CH2CH2-NH2 or -SS-C6H5-NH2.

17. The diaphragm according to claim 13, wherein, The main chain of the linear binder includes structural units containing alkylene glycol groups.

18. The septum of claim 13, wherein, The linear binder comprises one or more of the following chemical formulas 10 and 11, and dimethyl polyethylene glycol: Chemical Formula 10: ； Chemical Formula 11: ； Where n is the number of times each unit is repeated.

19. The septum of claim 13, wherein, The adhesive layer comprises the core-shell adhesive and the linear adhesive in a weight ratio ranging from 2:1 to 20:

1.

20. A rechargeable battery, said rechargeable battery comprising: Positive electrode; negative electrode; as well as The diaphragm according to any one of claims 1 to 19 is located between the positive electrode and the negative electrode.

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