Binder for rechargeable lithium battery, electrode comprising same, and rechargeable lithium battery comprising same

Abstract

Disclosed examples include a binder for a rechargeable lithium battery including a particulate binder of a core-shell structure and a linear binder, where at least one of the particulate binder of the core-shell structure and the linear binder includes a desired structural unit, and an electrode and a rechargeable lithium battery including the binder.

Description

Technical Field

[0001] A binder for rechargeable lithium batteries, as well as an electrode including the binder and a rechargeable lithium battery, are disclosed. Background Technology

[0002] With the increasing use of battery-powered electronic devices (such as mobile phones, laptops, and electric vehicles), the demand for small, lightweight, and relatively high-capacity rechargeable batteries is growing. Specifically, rechargeable lithium batteries are attracting attention as a power source for portable devices due to their light weight and high energy density.

[0003] A rechargeable lithium battery includes a positive electrode and a negative electrode containing active materials capable of inserting and deintercalating lithium ions, as well as an electrolyte, and generates electrical energy through a redox reaction when lithium ions are inserted and deintercalated from the positive electrode and the negative electrode.

[0004] Adhesives are included in the various components of these rechargeable lithium batteries. These adhesives can advantageously possess high adhesive strength, but adhesives with high adhesive strength typically have the disadvantage of high electrical resistance. Summary of the Invention

[0005] Some example embodiments include adhesives for rechargeable lithium batteries that have high adhesive strength and low resistance.

[0006] Some example embodiments include a binder for rechargeable lithium batteries, the binder comprising a core-shell structured particulate binder and a linear binder, wherein each or at least one of the core-shell structured particulate binder and the linear binder comprises a desired structural unit.

[0007] Some example embodiments include a negative electrode containing a binder for rechargeable lithium batteries.

[0008] Some example embodiments include rechargeable lithium batteries comprising a negative electrode, a positive electrode, and an electrolyte.

[0009] Some example embodiments of the adhesives for rechargeable lithium batteries have high adhesive strength and low resistance, which can help improve the performance of rechargeable lithium batteries. Attached Figure Description

[0010] Figures 1 to 4 This is a schematic diagram illustrating a rechargeable lithium battery according to some example embodiments. Detailed Implementation

[0011] Hereinafter, exemplary embodiments of the present disclosure are described in detail. However, these embodiments are exemplary, and the present disclosure is not limited thereto, and is defined by the scope of the claims.

[0012] As used herein, unless otherwise specifically defined, it is understood that when an element (such as a layer, film, region, or substrate) is referred to as being "on" another element, the element may be directly on the other element or there may be an intervening element.

[0013] As used herein, the singular may also include the plural unless otherwise specifically defined. Additionally, unless otherwise stated, “A or B” may mean “including A, including B, or including both A and B”.

[0014] As used herein, “combination of” can mean a mixture, stack, complex, copolymer, alloy, blend or reaction product of the components.

[0015] As used herein, unless otherwise defined, particle size can be the average particle size. This average particle size means the average particle size (D50) as the diameter of particles representing 50% of the cumulative volume in the particle size distribution. The average particle size (D50) can be measured by methods known to those skilled in the art, for example, by using a particle size analyzer, transmission electron microscope, or scanning electron microscope. Optionally, data analysis is performed using a dynamic light scattering measurement device, and the number of particles is counted for each particle size range. Thus, the average particle size (D50) value can be readily obtained by calculation. Laser diffraction can also be used. When measured by laser diffraction, more specifically, the particles to be measured are dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measurement device (e.g., the MT 3000 available from Microtrac Ltd.), using ultrasound at approximately 28 kHz, and after irradiation with an output of 60 W, the average particle size (D50) based on 50% of the particle size distribution in the measurement device can be calculated.

[0016] As used herein, unless otherwise specifically defined, “alkyl” means C1 to C20 alkyl, “alken” means C2 to C20 alken, “cycloalken” means C3 to C20 cycloalken, “heterocyclic alken” means C3 to C20 heterocyclic alken, “aryl” means C6 to C20 aryl, “arylalkyl” means C6 to C20 arylalkyl, “alkylene” means C1 to C20 alkylene, “arylene” means C6 to C20 arylene, “alkylarylene” means C6 to C20 alkylarylene, “heteroarylene” means C3 to C20 heteroarylene, and “alkoxide” means C1 to C20 alkoxide.

[0017] As used herein, unless otherwise specifically defined, “substituted” means that at least one hydrogen atom is replaced by a substituent such as or including a halogen atom (F, Cl, Br or I), hydroxyl, C1 to C20 alkoxy, nitro, cyano, amino, imino, azide, amido, hydrazine, hydrazone, carbonyl, carbamoyl, thiol, ester, ether, carboxyl or a salt thereof, sulfonic acid or a salt thereof, phosphate or a salt thereof, C1 to C20 alkyl, C2 to C20 alkenyl, C2 to C20 alkynyl, C6 to C20 aryl, C3 to C20 cycloalkyl, C3 to C20 cycloalkenyl, C3 to C20 cycloalkynyl, C2 to C20 heterocyclic alkyl, C2 to C20 heterocyclic alkenyl, C2 to C20 heterocyclic alkynyl, C3 to C20 heterocyclic aryl, and combinations thereof.

[0018] Additionally, as used herein, unless otherwise specifically defined, “heterogeneous” means a chemical formula containing at least one heteroatom of at least one of N, O, S, and P.

[0019] Additionally, as used herein, unless otherwise specifically defined, “(meth)acrylate” means both “acrylate” and “methacrylate”, and “(meth)acrylic acid” means both “acrylic acid” and “methacrylic acid”.

[0020] As used herein, unless otherwise specifically defined, “combination” means blend or copolymerization.

[0021] In the chemical formulas of this specification, unless otherwise specifically defined, when a chemical bond is not drawn at the position that should be given, hydrogen is bonded at that position.

[0022] In this specification, the weight-average molecular weight (Mw) can be a value measured using gel permeation chromatography (GPC).

[0023] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, it is intended that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0024] adhesive Some example embodiments include binders for rechargeable lithium-ion batteries, comprising core-shell structured particulate binders and linear binders, wherein each or at least one of the core-shell structured particulate binders and linear binders comprises a desired structural unit. A core-shell binder can refer to a particulate binder comprising a spherical core particle made of a polymer and a shell made of a polymer surrounding the surface of the core particle. A linear binder can refer to a linear polymer. A linear polymer is a class of polymers in which monomer units are linked together in long, continuous chains resembling a straight line. This structure is the opposite of branched or crosslinked polymers.

[0025] The particulate binder consists of a core-shell structure, and each or at least one of the core and shell may comprise an acrylic polymer. Compared to SBR (styrene-butadiene rubber) binders, this core-shell structured particulate binder can exhibit low resistance by including electrolyte-friendly functional groups, but may have the disadvantage of insufficient adhesive strength for use in rechargeable lithium batteries.

[0026] Linear binders have high adhesive strength, which makes them able to overcome the shortcomings of particulate binders with core-shell structures, and also have the advantages of desired or improved ionic conductivity and low resistance.

[0027] Therefore, some example embodiments of binders that simultaneously or concurrently include particulate binders and linear binders with core-shell structures have high adhesive strength and low resistance, which can thus help improve the performance of rechargeable lithium batteries.

[0028] The adhesive for rechargeable lithium batteries according to some example embodiments is described in detail below.

[0029] granular adhesive The core of a core-shell structured particulate binder may include a first structural unit derived from (meth)acrylate (C1-C20)alkyl or (C2-C20)alkenyl ester monomers (e.g., (meth)acrylate (C1-C10)alkyl ester monomers), a second structural unit derived from aromatic vinyl monomers, and a third structural unit derived from di(meth)acrylate monomers.

[0030] The first structural unit can be represented by chemical formula 1: Chemical Formula 1:

[0031] In chemical formula 1, R 1 It may be or include hydrogen atoms or C1 to C20 alkyl groups; and R 2 It may be or include substituted or unsubstituted C1 to C20 alkyl groups or substituted or unsubstituted C2 to C20 alkenyl groups.

[0032] For example, the first structural unit can be derived from 2-ethylhexyl acrylate. In this case, R 1 It can be or include hydrogen atoms, and R 2 It may include or contain 2-ethylhexyl.

[0033] The second structural unit can be represented by chemical formula 2: Chemical formula 2:

[0034] In chemical formula 2, R 3 It may be or include hydrogen atoms or C1 to C20 alkyl groups; and R 4 It may include or contain substituted or unsubstituted C6 to C20 aryl groups.

[0035] For example, the second structural unit can be derived from styrene. In this case, R 3 It can be or include hydrogen atoms, and R 4 It can be or include phenyl.

[0036] The third structural unit can be represented by chemical formula 3: Chemical formula 3:

[0037] In chemical formula 3, R 5 They may be the same or different, and may independently be or include hydrogen atoms or C1 to C20 alkyl groups; and m may be an integer in the range of 1 to 100.

[0038] For example, the third structural unit can be derived from diacrylates. In this case, all R 5 It can be a hydrogen atom, and m can be 1 or 2.

[0039] Based on a total amount of 100 wt% of the core, the first structural unit may be included in an amount ranging from about 35 wt% to about 60 wt%, about 38 wt% to about 55 wt%, or about 40 wt% to about 58 wt%; the second structural unit may be included in an amount ranging from about 35 wt% to about 60 wt%, about 38 wt% to about 55 wt%, or about 40 wt% to about 58 wt%; and the third structural unit may be included in an amount ranging from about 0.01 wt% to about 5 wt%, about 0.1 wt% to about 5 wt%, or about 0.3 wt% to about 2 wt%.

[0040] Within any of the above ranges, the first to third structural units are coordinated to exhibit low resistance.

[0041] The shell of a core-shell structured particulate binder may include a fourth structural unit derived from (meth)acrylic acid monomers or their salts, a fifth structural unit derived from (meth)acrylonitrile monomers, and a sixth structural unit derived from aromatic vinyl sulfonate monomers or their salts.

[0042] The fourth structural unit can be represented by chemical formula 4-1 or chemical formula 4-2: Chemical formula 4-1:

[0043] Chemical formula 4-2:

[0044] In chemical formulas 4-1 and 4-2, R 6 They can be the same or different, and can be independently composed of or include hydrogen atoms or C1 to C20 alkyl groups, and M1 can be an alkali metal.

[0045] For example, the fourth structural unit can be derived from acrylic acid. In this case, R 6 It can consist entirely of or include hydrogen atoms.

[0046] M1 can be derived from metal ions (e.g., lithium atoms) in the electrolyte.

[0047] The fifth structural unit can be represented by chemical formula 5: Chemical formula 5:

[0048] In chemical formula 5, R 7 It may be or include hydrogen atoms or C1 to C20 alkyl groups.

[0049] For example, the fifth structural unit can be derived from acrylonitrile. In this case, R 7 It can be or include hydrogen atoms.

[0050] The sixth structural unit can be represented by chemical formula 6-1 or chemical formula 6-2: Chemical formula 6-1:

[0051] Chemical formula 6-2:

[0052] In chemical formulas 6-1 and 6-2, R 8 They may be the same or different, and may independently be or include hydrogen atoms or C1 to C20 alkyl groups; L 1 They may be the same or different, and may independently be or include substituted or unsubstituted C6 to C20 arylene groups; and M2 may be or include alkali metals.

[0053] For example, the sixth structural unit can be derived from sodium styrene sulfonate. In this case, R 8 It can be or includes hydrogen atoms and L 1 It may include or contain phenylene.

[0054] M2 can be derived from metal ions (e.g., lithium atoms) in the electrolyte.

[0055] Based on a total shell content of 100 wt%, a fourth structural unit may be included in an amount ranging from about 25 wt% to about 60 wt%, about 30 wt% to about 60 wt%, or about 35 wt% to about 55 wt%; a fifth structural unit may be included in an amount ranging from about 25 wt% to about 47 wt%, about 28 wt% to about 47 wt%, or about 30 wt% to about 45 wt%; and a sixth structural unit may be included in an amount ranging from about 3 wt% to about 35 wt%, about 5 wt% to about 35 wt%, or about 10 wt% to about 30 wt%.

[0056] Within the above range, the fourth to sixth structural units are coordinated to exhibit low resistance.

[0057] The weight ratio of the core to the shell in a core-shell structured particulate binder can be in the range of about 100:0.1 to about 100:20, about 100:0.5 to about 100:10, or about 100:1 to about 100:5.

[0058] Within the above range, the core and shell can exhibit low resistance.

[0059] The core-shell structured particulate binder can be located in the matrix portion of the electrode active material layer, and the trade-off between adhesive strength and resistance can be controlled by adjusting the particle size during manufacturing.

[0060] For example, the average particle size (D50) of a core-shell structured particulate binder can be in the range of about 450 nm to about 1500 nm (e.g., about 450 nm to about 700 nm). This is larger than the average particle size (D50) of about 2 nm to about 300 nm of commonly used particulate binders and can exhibit low resistivity.

[0061] The core-shell structured particulate binder may have a weight-average molecular weight (Mw) in the range of about 20,000 g / mol to about 2,500,000 g / mol (e.g., about 50,000 g / mol to about 1,500,000 g / mol).

[0062] The above range is suitable for application in electrode active material layers. Here, the weight-average molecular weight can be expressed as a value calculated in polystyrene using gel permeation chromatography.

[0063] linear adhesive Linear binders may include a seventh structural unit derived from (meth)acrylic monomers or their salts, an eighth structural unit derived from (meth)acrylonitrile monomers, and a ninth structural unit derived from zwitterionic monomers.

[0064] The seventh structural unit can be represented by chemical formula 7-1 or chemical formula 7-2: Chemical formula 7-1:

[0065] Chemical formula 7-2:

[0066] In chemical formulas 7-1 and 7-2, R 9 They may be the same or different, and may be or include hydrogen atoms or C1 to C20 alkyl groups independently; and M3 may be an alkali metal.

[0067] For example, the seventh structural unit can be derived from acrylic acid, and all R 9 It can be or include hydrogen atoms.

[0068] M3 can be derived from metal ions (e.g., lithium atoms) in the electrolyte.

[0069] The eighth structural unit can be represented by the chemical formula 8: Chemical formula 8:

[0070] In chemical formula 8, R 10 It may be or include hydrogen atoms or C1 to C20 alkyl groups.

[0071] The eighth structural unit can be derived from acrylonitrile. In this case, R 10 It can be or include hydrogen atoms.

[0072] The ninth structural unit can be represented by chemical formula 9-1 or chemical formula 9-2: Chemical formula 9-1:

[0073] Chemical formula 9-2:

[0074] In chemical formulas 9-1 and 9-2, R 11 They may be the same or different, and may independently be or include hydrogen atoms or C1 to C20 alkyl groups; R 12 They may be the same or different, and may independently be or include hydrogen atoms or C1 to C20 alkyl groups; L 2 It can be *-(C=O)-NR 12 -CH2-* or *-(C=O)-O-*; and L 3 To L 5 It can be independently or include single bonds or C1 to C20 alkylene groups.

[0075] When the ninth structural unit is derived from sulfobetaine (SB) and represented by chemical formula 9-1, R 11 It may include or contain methyl; L 2 It can be or include *-(C=O)-NR 12 -CH2-* or *-(C=O)-O-*; and L 3 and L 4 Both can be or include ethylene.

[0076] When the ninth structural unit is derived from vinylimidazolium sulfonate (IMS) and represented by chemical formula 9-2, R 11 It can be or may include hydrogen atoms; and L 5 It can be or include butylene.

[0077] Based on the total amount of 100 wt% linear binder, a seventh structural unit may be included in an amount ranging from about 30 wt% to about 60 wt%, about 45 wt% to about 60 wt%, or about 45 wt% to about 55 wt%; an eighth structural unit may be included in an amount ranging from about 32 wt% to about 55 wt%, about 35 wt% to about 55 wt%, or about 35 wt% to about 50 wt%; and a ninth structural unit may be included in an amount ranging from about 1 wt% to about 15 wt%, about 3 wt% to about 15 wt%, or about 5 wt% to about 15 wt%.

[0078] Within the above range, the seventh to ninth structural units are coordinated to have high adhesive strength, which can compensate for the disadvantages of particulate binders in core-shell structures, while also having the advantages of desired or improved ionic conductivity and low resistance.

[0079] Linear binders may also include a tenth structural unit derived from (C1-C10) alkylene glycol monomers or their salts.

[0080] The tenth structural unit can be represented by chemical formula 10-1 or chemical formula 10-2: Chemical formula 10-1:

[0081] Chemical formula 10-2:

[0082] In chemical formula 10⁻¹ or chemical formula 10⁻², M₄ can be or include alkali metals, and n can be an integer in the range of 1 to 100.

[0083] For example, the tenth structural unit can be derived from ethylene glycol. In this case, n can be between 5 and 20 or between 5 and 10.

[0084] M4 can be derived from metal ions (e.g., lithium atoms) in the electrolyte.

[0085] Based on a total amount of 100 wt% linear binder, the tenth structural unit may be included in an amount ranging from about 0.1 wt% to about 15 wt%, about 1 wt% to about 15 wt%, or about 3 wt% to about 10 wt%.

[0086] In this case, the tenth structural unit can help further reduce resistance by increasing the ionic conductivity of the linear binder.

[0087] Linear binders can have a weight-average molecular weight (Mw) in the range of about 20,000 g / mol to about 2,500,000 g / mol (e.g., about 50,000 g / mol to about 1,500,000 g / mol).

[0088] Within the above range, linear binders can be coated onto the active material layer. Here, the weight-average molecular weight can be expressed as a value calculated in polystyrene using gel permeation chromatography.

[0089] Preparation methods for each type of adhesive Each or at least one of the above monomer mixtures can be polymerized using conventional methods known to those skilled in the art to prepare the binder.

[0090] Among these methods, a particulate binder for a core-shell structure can be provided by preparing a core comprising a first to a third structural unit from raw materials of the core and mixing raw materials of the shell therein to form a shell comprising a fourth to a sixth structural unit on the surface of the core.

[0091] Polymerization can be or includes at least one of emulsion polymerization, suspension polymerization, solution polymerization, etc.

[0092] Emulsifiers may be or include at least one or a combination of higher fatty acid alkali metal salts, N-acryloyl amino acid salts, alkyl ether carbonates, acylated peptides, alkyl sulfonates, alkylbenzene sulfonates, alkyl amino acid salts, alkylnaphthalene sulfonates, sulfosuccinates, sulfonated oils, alkyl sulfates, alkyl ether sulfates, alkyl aryl ether sulfates, alkylamide sulfates, alkyl phosphates, alkyl ethoxy phosphates, and alkyl aryl ether phosphates. Examples of emulsifiers may include sodium dodecylbenzene sulfonate. Alkyl groups may be or include alkyl groups having 1 to 20 carbon atoms.

[0093] The initiator may be or include an azo compound initiator (such as or include at least one of azobisisobutyronitrile, ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide and combinations thereof).

[0094] Based on the total content of 100 parts by weight of the monomer mixture, the emulsifier content can be in the range of about 0.1 parts by weight to about 3 parts by weight or about 0.1 parts by weight to about 2 parts by weight. When the emulsifier content is within the above range, the adhesive strength can be further improved, and an adhesive with the desired size can be obtained, resulting in good dispersion.

[0095] Based on the total content of 100 parts by weight of the monomer mixture, the content of the initiator can be in the range of about 0.1 parts by weight to about 3 parts by weight, or it can be about 0.1 parts by weight to about 2 parts by weight.

[0096] The mixing ratio of core-shell structured particulate binders to linear binders The core-shell structured particulate binder and linear binder can be mixed in a weight ratio ranging from about 100:1 to about 1:1, about 50:1 to about 1:1, or about 8:1 to about 1:1. Within these ranges, the complementary effect of the core-shell structured particulate binder and linear binder can be most desirable or most improved.

[0097] electrode Some example embodiments include electrodes for rechargeable lithium batteries, the electrodes comprising: the binder described above according to some example embodiments; and electrode active material.

[0098] The electrode can be or may include a negative electrode or a positive electrode. Even when the binder is included in the negative electrode, which undergoes large volume changes due to the charging and discharging of the rechargeable lithium battery, the binder has high adhesive strength and low resistance, which can help improve the performance of the rechargeable lithium battery.

[0099] The following describes in detail electrodes for rechargeable lithium batteries according to some example embodiments.

[0100] Negative electrode active material The negative electrode active material may include at least one of the following: materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium metal alloys, materials capable of doping / dedoping lithium, and transition metal oxides.

[0101] Materials that can reversibly insert / deintercalate lithium ions can include, for example, crystalline carbon, amorphous carbon, or combinations thereof as carbon-based negative electrode active materials. Crystalline carbon can be irregular, sheet-like, flake-like, spherical, or fibrous natural or artificial graphite. Amorphous carbon can be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0102] The lithium metal alloy includes an alloy of lithium and a metal such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0103] The material capable of doping / dedoping lithium can be or include at least one of Si-based negative electrode active materials and Sn-based negative electrode active materials. The Si-based negative electrode active material can include silicon, silicon-carbon composite, SiO x (0 < x ≤ 2), Si-Q alloy (where Q is an element such as or including 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), or a combination thereof. The Sn-based negative electrode active material can be or include at least one of Sn, SnO2, Sn-based alloys, and combinations thereof.

[0104] The silicon-carbon composite can be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) in which primary silicon particles are assembled and an amorphous carbon coating layer (shell) on the surface of the secondary particles. Amorphous carbon can also be present between the primary silicon particles. For example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0105] The silicon-carbon composite can also include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core.

[0106] The Si-based negative electrode active material or the Sn-based negative electrode active material can be mixed with a carbon-based negative electrode active material.

[0107] negative electrode The negative electrode for a rechargeable lithium battery includes a current collector and a negative electrode active material layer on the current collector. The negative electrode active material layer includes a negative electrode active material and can also include a binder and / or a conductive material. The binder can be or include the binder of the前述示例实施例 (it seems there is a mistake here, maybe it should be 'the foregoing exemplary embodiments').

[0108] For example, the negative electrode active material layer can include about 90 wt% to about 99 wt% or about 90 wt% to about 99.5 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0.5 wt% to about 5 wt% of the conductive material.

[0109] The binder is configured to adhere the negative electrode active material particles to each other and also to the negative electrode active material in the current collector. The binder may be or include non-aqueous binders, aqueous binders, dry binders, or combinations thereof.

[0110] Non-aqueous adhesives may include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, and combinations thereof.

[0111] Waterborne adhesives may 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.

[0112] When an aqueous binder is included as the negative electrode binder, a cellulose compound capable of imparting viscosity may also be included. As a cellulose compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be mixed and used. The alkali metal may be or include at least one of Na, K, and Li.

[0113] The dry adhesive may be or include a polymeric material capable of being converted into fibers, and may be or include at least one of, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and combinations thereof.

[0114] The device includes conductive materials to provide conductivity to the electrodes, and may include any electrically conductive material as a conductive material unless the conductive material causes a chemical change in the battery or causes a chemical change in the battery. Examples of conductive materials include: carbon-based materials, such as or including at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fiber; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0115] The negative electrode current collector may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0116] Positive electrode active material The positive electrode active material can be or includes compounds capable of intercalating and deintercalating lithium (lithium-intercalating compounds). Specifically, a composite oxide of lithium with one or more types of metals such as or including at least one of cobalt, manganese, nickel, and combinations thereof can be used.

[0117] The composite oxide can be or includes lithium transition metal composite oxides, and examples may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and combinations thereof.

[0118] As an example, a compound 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, 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, 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, 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, 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G bO2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0119] In the above chemical formulas, A is or includes at least one of Ni, Co, Mn, and combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is or includes at least one of O, F, S, P, and combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; and L 1 It may include at least one of Mn, Al, and combinations thereof.

[0120] The positive electrode active material may be or include at least one of the following: lithium nickel oxide represented by chemical formula 11, lithium cobalt oxide represented by chemical formula 12, lithium iron phosphate compound represented by chemical formula 13, cobalt-free lithium nickel manganese oxide represented by chemical formula 14, and combinations thereof.

[0121] Chemical Formula 11: Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 In chemical formula 11, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each of them independently comprises or includes one or more of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X comprises or includes one or more of F, P, and S.

[0122] In Chemical Formula 11, 0.6 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.4 and 0 ≤ z1 ≤ 0.4, or 0.8 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.2 and 0 ≤ z1 ≤ 0.2.

[0123] Chemical Formula 12: Li a2 Co x2 M 3 y2 O 2-b2 X b2 In Chemical Formula 12, 0.9 ≤ a2 ≤ 1.8, 0.7 ≤ x2 ≤ 1, 0 ≤ y2 ≤ 0.3, 0.9 ≤ x2 + y2 ≤ 1.1, and 0 ≤ b2 ≤ 0.1, M 3 is or includes one or more of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is or includes one or more of F, P, and S.

[0124] Chemical Formula 13: Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 In Chemical Formula 13, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, and 0 ≤ b3 ≤ 0.1, M 4 is or includes one or more of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is or includes one or more of F, P, and S.

[0125] Chemical Formula 14: Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4 In Chemical Formula 14, 0.9 ≤ a4 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1, M 5X is or includes one or more of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is or includes one or more of F, P, and S.

[0126] For example, the positive electrode active material can be or includes a high-nickel positive electrode active material, in which, based on 100 mol% of metals other than lithium in the lithium transition metal complex oxide, the nickel content is greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be applied to, for example, high-capacity, high-density rechargeable lithium batteries.

[0127] positive electrode The positive electrode for a rechargeable lithium battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer may include a positive electrode active material and may also include a binder and / or a conductive material. The binder may be or include the binder of the foregoing example embodiments.

[0128] For example, the positive electrode may also include additives that can constitute a sacrificial positive electrode.

[0129] Based on a 100wt% positive electrode active material layer, the content of the positive electrode active material can be in the range of about 90wt% to about 99wt% or about 90wt% to about 99.5wt%, and based on the 100wt% positive electrode active material layer, the respective contents of the binder and the conductive material can be in the range of about 0.5wt% to about 5wt%.

[0130] The binder improves the adhesion properties between the positive electrode active material particles and between the positive electrode active material particles and the current collector. Examples of binders may include, but are not limited to, at least one of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, and nylon.

[0131] The material may include conductive materials to provide conductivity to the electrodes, and may include any electrically conductive material as a conductive material unless the conductive material causes a chemical change in the battery or causes a chemical change in the battery. Examples of conductive materials may include: carbon-based materials, such as or including at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fiber; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0132] The current collector may include, but is not limited to, Al.

[0133] electrolyte Electrolytes can be or include solid electrolytes or liquid electrolytes (i.e., electrolyte solutions).

[0134] Electrolytes used in rechargeable lithium batteries include non-aqueous organic solvents and lithium salts.

[0135] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0136] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and combinations thereof.

[0137] 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 (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC). Ester solvents may include at least one of methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolactone, mevalonolactone, valproic acid lactone, and caprolactone. Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. Additionally, ketone solvents may include cyclohexanone. Alcohol solvents may include at least one of ethanol, isopropanol, etc., and aprotic solvents may include at least one of the following: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched or cyclic hydrocarbon group, and may include double bonds, aromatic rings or ether groups, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0138] Non-aqueous organic solvents may be included alone or as a mixture of two or more types of solvents.

[0139] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0140] Lithium salts dissolved in organic solvents are configured to supply lithium ions in batteries to enable basic operation of rechargeable lithium batteries and improve lithium ion transport between the positive and negative electrodes. Examples of lithium salts may include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), lithium difluorobis(oxalate)borate (LiDFBOB), and lithium bis(oxalate)borate (LiBOB).

[0141] diaphragm Depending on the type of rechargeable lithium battery, a separator may be present between the positive and negative electrodes. The separator may include at least one of polyethylene, polypropylene, polyvinylidene fluoride, and multilayer films with two or more layers, such as mixed multilayer films such as polyethylene / polypropylene bilayer separators, polyethylene / polypropylene / polypropylene trilayer separators, polypropylene / polypropylene / polypropylene trilayer separators, etc.

[0142] The membrane may include a porous substrate and a coating layer on one or both surfaces of the porous substrate, the coating layer comprising an organic material, an inorganic material, or a combination thereof.

[0143] The porous substrate may be or include a polymer membrane formed of or comprising any one of the following polymers or copolymers or mixtures thereof: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryl etherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (Teflon).

[0144] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0145] Inorganic materials may include, but are not limited to, inorganic particles containing at least one of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0146] Organic and inorganic materials can be mixed in a coating layer, or a coating layer containing organic materials and a coating layer containing inorganic materials can be stacked together.

[0147] Rechargeable lithium batteries Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch, or coin-shaped batteries. Figures 1 to 4 This is a schematic diagram illustrating a rechargeable lithium battery according to some example embodiments, wherein... Figure 1 It is a cylindrical battery. Figure 2 It is a prismatic battery. Figure 3 and Figure 4 It is a pouch battery. (See reference) Figures 1 to 4 The rechargeable lithium battery 100 includes an electrode assembly 40 having a separator 30 disposed between a positive electrode 10 and a negative electrode 20, and a housing 50 therein housing the electrode assembly 40. The positive electrode 10, the negative electrode 20, and the separator 30 can be impregnated with an electrolyte (not shown). Figure 1 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of a sealed housing 50. For example, in Figure 2 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 3 and Figure 4 As shown, the rechargeable lithium battery 100 includes Figure 4 The electrode connector 70 shown is or Figure 3 The positive electrode terminal 71 and negative electrode terminal 72 shown form an electrical path for guiding the current generated in the electrode assembly 40 to the outside of the battery 100.

[0148] The rechargeable lithium battery according to some example embodiments can be used in, for example, automobiles, mobile phones and / or various types of electronic devices, but this disclosure is not limited thereto.

[0149] 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 the following examples.

[0150] Examples and Comparison Examples Preparation Example 1: Preparation of Core-Shell Structured Particulate Binder A first monomer mixture comprising 50 wt% 2-ethylhexyl acrylate (2-EHA), 49.5 wt% styrene (ST), and 0.5 wt% bis(ethylene glycol) diacrylate (PEGDA) was prepared, and an azo compound initiator and water were added to it. The azo compound initiator was included in an amount of 0.2 parts by weight per 100 parts by weight of the first monomer mixture.

[0151] Subsequently, the resulting mixture is subjected to emulsion polymerization to obtain a solution comprising a core containing a first structural unit derived from 2-ethylhexyl acrylate, a second structural unit derived from styrene, and a third structural unit derived from bis(ethylene glycol) diacrylate.

[0152] On the other hand, a second monomer mixture comprising 35 wt% acrylic acid (AA), 35 wt% acrylonitrile (AN) and 30 wt% sodium styrene sulfonate (NaSS) was prepared.

[0153] Based on 100 parts by weight of the core (i.e., the first monomer mixture) in a solution including the core, a second monomer mixture is added to the first monomer mixture at a rate of 5 parts by weight, and then mixed with an azo compound initiator and water. Based on 100 parts by weight of the second monomer mixture, the azo compound initiator is included at a rate of 0.2 parts by weight. As a result, a solution of a particulate binder comprising a core-shell structure is obtained.

[0154] The average particle size (D50) of the core-shell structured particulate binder was measured under number-average particle size distribution conditions using a dynamic light scattering device, wherein the average particle size (D50) was 1,120 nm, and the weight-average molecular weight of the core-shell structured particulate binder, calculated in polystyrene equivalents by gel permeation chromatography, was 950,000 g / mol.

[0155] Preparation Example 2-1: Preparation of Linear Binders 100 parts by weight of a third monomer mixture comprising 50 wt% acrylic acid (AA), 40 wt% acrylonitrile (AN), and 10 wt% sulfobetaine (SB) are mixed with an azo compound initiator and water. Based on 100 parts by weight of the third monomer mixture, the azo compound initiator is included in an amount of 0.2 parts by weight.

[0156] Subsequently, the obtained mixture is subjected to emulsion polymerization to prepare a solution comprising a linear binder comprising a copolymer containing a seventh structural unit derived from acrylic acid, an eighth structural unit derived from acrylonitrile, and a ninth structural unit derived from sulfobetaine.

[0157] The linear binder has a weight-average molecular weight of 720,500 g / mol, calculated as polystyrene equivalents by gel permeation chromatography.

[0158] Preparation Example 2-2: Preparation of Linear Binders The solution comprising the linear binder was prepared in the same manner as in Preparation Example 2-1, except that a third monomer mixture was prepared by mixing 49 wt% acrylic acid (AA), 36 wt% acrylonitrile (AN) and 15 wt% sulfobetaine (SB).

[0159] The linear binder has a weight-average molecular weight of 901,000 g / mol, calculated as polystyrene equivalents by gel permeation chromatography.

[0160] Preparation Example 2-3: Preparation of Linear Binders A solution comprising a linear binder was prepared in the same manner as in Preparation Example 2-1, except that vinylimidazolium sulfonate (IMS) was used instead of sulfobetaine (SB).

[0161] The linear binder has a weight-average molecular weight of 754,000 g / mol, calculated as polystyrene equivalents by gel permeation chromatography.

[0162] Preparation Example 2-4: Preparation of Linear Binders The solution comprising the linear binder was prepared in the same manner as in Preparation Example 2-1, except that the third monomer mixture was prepared by mixing 51 wt% acrylic acid (AA), 39 wt% acrylonitrile (AN), 5 wt% sulfobetaine (SB) and 5 wt% ethylene glycol (EG) (ethylene glycol repetition number (n) = 8).

[0163] Therefore, a solution comprising a linear binder is prepared, the linear binder comprising a copolymer containing a seventh structural unit derived from acrylic acid, an eighth structural unit derived from acrylonitrile, a ninth structural unit derived from sulfobetaine, and a tenth structural unit derived from ethylene glycol (ethylene glycol repeat number (n) = 8).

[0164] The linear binder has a weight-average molecular weight of 963,000 g / mol, calculated as polystyrene equivalents by gel permeation chromatography.

[0165] Preparation Example 2-5: Preparation of Linear Binders The solution comprising the linear binder was prepared in the same manner as in Preparation Example 2-1, except that the third monomer mixture was prepared by mixing 49 wt% acrylic acid (AA), 41 wt% acrylonitrile (AN), 7 wt% sulfobetaine (SB) and 3 wt% ethylene glycol (ethylene glycol repetition number (n) = 8).

[0166] Therefore, a solution comprising a linear binder is prepared, the linear binder comprising a copolymer containing a seventh structural unit derived from acrylic acid, an eighth structural unit derived from acrylonitrile, a ninth structural unit derived from sulfobetaine, and a tenth structural unit derived from ethylene glycol (ethylene glycol repeat number (n) = 8).

[0167] The linear binder has a weight-average molecular weight of 940,500 g / mol, calculated as polystyrene equivalents by gel permeation chromatography.

[0168] Example 1 (1) Preparation of adhesive The adhesive was prepared by mixing 1.5 parts by weight of the particulate binder with a core-shell structure from Preparation Example 1 and 1 part by weight of the linear binder from Preparation Example 2-1.

[0169] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% of graphite negative electrode active material and 2.5 wt% of the binder in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0170] (3) Manufacturing of the positive electrode 97.7wt% LiNi 0.88 Co 0.105 Al 0.015 O2 positive electrode active material, 1.3 wt% polyvinylidene fluoride binder and 1.0 wt% carbon nanotube conductive material are mixed to prepare positive electrode active material layer slurry. The positive electrode active material layer slurry is coated on aluminum foil current collector, then dried and compressed to manufacture positive electrode.

[0171] (4) Preparation of electrolyte An electrolyte was prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 2:4:4 to prepare an organic solvent, and then dissolving lithium LiPF6 salt in the organic solvent at a concentration of 1.15 M.

[0172] (5) Manufacturing of rechargeable lithium battery cells The positive and negative electrodes are assembled using a 14μm thick polyethylene separator to manufacture an electrode assembly. The electrode assembly is housed in a prismatic housing and an electrolyte is injected into it to manufacture a rechargeable lithium battery cell.

[0173] Example 2 (1) Preparation of adhesive The adhesive was prepared by mixing 1.5 parts by weight of the particulate binder with a core-shell structure from Preparation Example 1 and 0.5 parts by weight of the linear binder from Preparation Example 2-1.

[0174] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% of graphite negative electrode active material, 2 wt% of the binder, and 0.5 wt% of carboxymethyl cellulose (CMC) as a thickener in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0175] (3) Manufacturing of rechargeable lithium battery cells The rechargeable lithium battery cell is manufactured in the same manner as in Example 1, except that the negative electrode is used.

[0176] Example 3 (1) Preparation of adhesive The adhesive was prepared by mixing 1.5 parts by weight of the particulate binder with a core-shell structure from Preparation Example 1 and 0.2 parts by weight of the linear binder from Preparation Example 2-1.

[0177] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% of graphite negative electrode active material, 1.7 wt% of the binder, and 0.8 wt% of carboxymethyl cellulose (CMC) as a thickener in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0178] (3) Manufacturing of rechargeable lithium battery cells The rechargeable lithium battery cell is manufactured in the same manner as in Example 1, except that the negative electrode is used.

[0179] Example 4 The negative electrode and the rechargeable lithium battery cell were manufactured in the same manner as in Example 1, except that the linear binder used in Preparation Example 2-2 was used instead of the linear binder used in Preparation Example 2-1.

[0180] Example 5 The negative electrode and the rechargeable lithium battery cell were manufactured in the same manner as in Example 1, except that the linear binder used in the preparation of Example 2-3 was used instead of the linear binder used in the preparation of Example 2-1.

[0181] Example 6 The negative electrode and the rechargeable lithium battery cell were manufactured in the same manner as in Example 1, except that the linear binder used in the preparation of Example 2-4 was used instead of the linear binder used in the preparation of Example 2-1.

[0182] Example 7 The negative electrode and the rechargeable lithium battery cell were manufactured in the same manner as in Example 1, except that the linear binder used in the preparation of Example 2-5 was used instead of the linear binder used in the preparation of Example 2-1.

[0183] Comparison Example 1 (1) Adhesive SBR (styrene-butadiene rubber) is used as the binder.

[0184] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% of graphite negative electrode active material, 1.5 wt% of the binder, and 1 wt% of carboxymethyl cellulose (CMC) as a thickener in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0185] (3) Manufacturing of rechargeable lithium battery cells The rechargeable lithium battery cell is manufactured in the same manner as in Example 1, except that the negative electrode is used.

[0186] Comparison Example 2 (1) Adhesive The particulate binder used in the preparation of the core-shell structure in Example 1 was used as the binder.

[0187] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% of graphite negative electrode active material, 1.5 wt% of the binder, and 1 wt% of carboxymethyl cellulose (CMC) as a thickener in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0188] (3) Manufacturing of rechargeable lithium battery cells The rechargeable lithium battery cell is manufactured in the same manner as in Example 1, except that the negative electrode is used.

[0189] Compare Example 3 (1) Adhesive The particulate binder used in the preparation of the core-shell structure in Example 1 was used as the binder.

[0190] (2) Manufacturing of the negative electrode A negative electrode active material slurry was prepared by mixing 97.5 wt% graphite negative electrode active material, 1.5 wt% of the binder, and 1 wt% polyacrylic acid (PAA) in an aqueous solvent. The negative electrode active material slurry was coated onto a copper foil current collector, dried, and compressed to manufacture the negative electrode.

[0191] (3) Manufacturing of rechargeable lithium battery cells The rechargeable lithium battery cell is manufactured in the same manner as in Example 1, except that the negative electrode is used.

[0192] Table 1:

[0193] The description in Table 1 is as follows.

[0194] The respective contents of 2-ethylhexyl acrylate (2-EHA), styrene (ST) and bis(ethylene glycol) diacrylate (PEGDA) based on a 100 wt% core are expressed in wt%.

[0195] The individual contents of acrylic acid (AA), acrylonitrile (AN) and sodium styrene sulfonate (NaSS) based on 100 wt% of the shell are expressed in wt%.

[0196] The weight ratio of the core to the shell is expressed as core:shell.

[0197] For linear binders, the respective contents of acrylic acid (AA), acrylonitrile (AN), and sulfobetaine (SB) as linear binders based on 100 wt% or the respective contents of acrylic acid (AA), acrylonitrile (AN), sulfobetaine (SB), and ethylene glycol (EG) as linear binders based on 100 wt% are expressed in wt%.

[0198] Evaluation Example Evaluation Example 1: Adhesion strength of the negative electrode The adhesion strength of each of the negative electrodes in Examples 1 to 7 and Comparative Examples 1 to 3 was evaluated according to three criteria, and the results are shown in Table 2 below.

[0199] (1) The extent of negative electrode detachment The weight and area of ​​the negative electrode active material layer of each of Examples 1 to 7 and Comparative Examples 1 to 3 were measured (excluding the previous weight and area).

[0200] Subsequently, the rechargeable lithium battery cells, including negative electrodes of Examples 1 to 7 and Comparative Examples 1 to 3 respectively, were charged to 100% SOC (State of Charge) and disassembled to measure the weight and area (weight and area after removal) of the active material layer of each negative electrode.

[0201] The degree of detachment of each negative electrode was evaluated as an integer from 1 to 3 according to the following criteria, and the results are shown in Table 1.

[0202] 1: (Weight before detachment - Weight after detachment) / Weight before detachment is 70wt% or greater, and / or (Area before detachment - Area after detachment) / Area before detachment is 70sq% or greater.

[0203] 2: (Weight before removal - Weight after removal) / Weight before removal is 10wt% or more and less than 70wt%, and / or (Area before removal - Area after removal) / Area before removal is 10sq% or more and less than 70sq.

[0204] 3: (Weight before detachment - Weight after detachment) / Weight before detachment is less than 10wt%, and / or (Area before detachment - Area after detachment) / Area before detachment is less than 10sq.

[0205] (2) Dry bond strength Each of the negative electrodes of Examples 1 to 7 and Comparative Examples 1 to 3 was attached to a support with double-sided tape and measured using a universal testing machine at a speed of 100 mm / min and a 90° angle. o The force required to peel the negative electrode active material layer from the current collector is called the "dry bond strength".

[0206] (3) Wet bond strength Each of the negative electrodes of Examples 1 to 7 and Comparative Examples 1 to 3 was immersed in the electrolyte at 45°C for 300 minutes and then removed from the electrolyte. They were then attached to a support using double-sided adhesive tape and measured again using a universal testing machine at a speed of 100 mm / min and a 90°C. o The force required to peel the active material layer of the negative electrode from the current collector is called the "wet adhesion strength". Here, the same electrolyte as in Example 1 is used as the electrolyte.

[0207] Evaluation Example 2: Room Temperature Characteristics of Rechargeable Lithium-ion Battery Cells The room temperature DC internal resistance (DC-IR) and room temperature lifetime characteristics of each of the negative electrodes of Examples 1 to 7 and Comparative Examples 1 to 3 were evaluated using the following three methods, and the results are shown in Table 2.

[0208] (1) DC-IR The ΔV / ΔI (voltage change / current change) of each of the rechargeable lithium-ion battery cells in Examples 1 to 7 and Comparative Examples 1 to 3 was measured at 25°C, which was considered as the initial DC resistance. The results are shown in Table 2.

[0209] At 25°C, under the conditions of 0.7C charging (CC / CV, 4.25V, 0.05C cutoff) / 0.7C discharging (CC, 2.8V cutoff), each of the rechargeable lithium battery cells of Examples 1 to 7 and Comparative Examples 1 to 3 was subjected to 200 charge-discharge cycles to calculate the capacity retention rate according to Equation 1.

[0210] Equation 1: Capacity retention % = (Discharge capacity after 200 cycles / Discharge capacity after 1 cycle) × 100 Table 2:

[0211] Summarize Referring to Tables 1 and 2, the binders for rechargeable lithium batteries according to some example embodiments, represented by Examples 1 to 7, have low resistance and high adhesion, and have thus been shown to help improve the performance of rechargeable lithium batteries.

[0212] While this disclosure has been described in conjunction with exemplary embodiments now considered practical, it will be understood that the disclosure is not limited to the disclosed exemplary embodiments. Rather, this disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0213] Description of reference numerals in the attached figures: 100: Rechargeable lithium battery 10: Positive electrode 11: Positive electrode lead connector 12: Positive electrode terminal 20: Negative electrode 21: Negative electrode lead connector 22: Negative electrode terminal 30: Diaphragm 40: Electrode assembly 50: Casing 60: Sealing component 70: Electrode connector 71: Positive electrode connector 72: Negative electrode connector.

Claims

1. A binder for rechargeable lithium batteries, said binder comprising a core-shell structured particulate binder and a linear binder. in, The core-shell structured particulate binder includes: The core comprises a first structural unit derived from a (C1-C20)alkyl or (C2-C20)alkenyl ester monomer of (meth)acrylate, a second structural unit derived from an aromatic vinyl monomer, and a third structural unit derived from a di(meth)acrylate monomer; and The shell comprises a fourth structural unit derived from (meth)acrylic acid monomers or their salts, a fifth structural unit derived from (meth)acrylonitrile monomers, and a sixth structural unit derived from aromatic vinyl sulfonate monomers or their salts. The linear binder comprises a seventh structural unit derived from (meth)acrylic monomers or their salts, an eighth structural unit derived from (meth)acrylonitrile monomers, and a ninth structural unit derived from zwitterionic monomers.

2. The adhesive according to claim 1, wherein: The first structural unit is represented by chemical formula 1. The second structural unit is represented by chemical formula 2, and The third structural unit is represented by chemical formula 3: Chemical Formula 1: In chemical formula 1, R 1 Including hydrogen atoms or C1 to C20 alkyl groups; and R 2 Including substituted or unsubstituted C1 to C20 alkyl groups or substituted or unsubstituted C2 to C20 alkenyl groups. Chemical formula 2: In chemical formula 2, R 3 Includes hydrogen atoms or C1 to C20 alkyl groups; and R 4 Including substituted or unsubstituted C6 to C20 aryl groups, Chemical formula 3: In chemical formula 3, R 5 Identical or different, and independently comprising hydrogen atoms or C1 to C20 alkyl groups; and m is an integer in the range of 1 to 100.

3. The adhesive according to claim 1, wherein, Based on a total amount of 100 wt% of the core, the first structural unit is included in an amount ranging from 35 wt% to 60 wt%, the second structural unit is included in an amount ranging from 35 wt% to 60 wt%, and the third structural unit is included in an amount ranging from 0.01 wt% to 5 wt%.

4. The adhesive according to claim 1, wherein: The fourth structural unit is represented by chemical formula 4-1 or chemical formula 4-2. The fifth structural unit is represented by chemical formula 5, and The sixth structural unit is represented by chemical formula 6-1 or chemical formula 6-2: Chemical formula 4-1: Chemical formula 4-2: Among them, in chemical formulas 4-1 and 4-2, R 6 Identical or different, and independently comprising hydrogen atoms or C1 to C20 alkyl groups; and M1 includes alkali metals. Chemical formula 5: In chemical formula 5, R 7 Includes hydrogen atoms or C1 to C20 alkyl groups, Chemical formula 6-1: Chemical formula 6-2: Among them, in chemical formulas 6-1 and 6-2, R 8 They may be the same or different, and each independently includes a hydrogen atom or a C1 to C20 alkyl group; L 1 Identical or different, and independently comprising substituted or unsubstituted C6 to C20 arylene groups; and M2 includes alkali metals.

5. The adhesive according to claim 1, wherein, Based on a total shell content of 100 wt%, the fourth structural unit is included in an amount ranging from 25 wt% to 60 wt%, the fifth structural unit is included in an amount ranging from 25 wt% to 47 wt%, and the sixth structural unit is included in an amount ranging from 3 wt% to 35 wt%.

6. The adhesive according to claim 1, wherein, The weight ratio of the core to the shell in the particulate binder of the core-shell structure is in the range of 100:0.1 to 100:

20.

7. The adhesive according to claim 1, wherein, The average particle size D50 of the core-shell structured particulate binder is in the range of 450 nm to 1500 nm.

8. The adhesive according to claim 1, wherein: The seventh structural unit is represented by chemical formula 7-1 or chemical formula 7-2. The eighth structural unit is represented by chemical formula 8, and The ninth structural unit is represented by chemical formula 9-1 or chemical formula 9-2: Chemical formula 7-1: Chemical formula 7-2: Among them, in chemical formulas 7-1 and 7-2, R 9 Identical or different, and independently comprising hydrogen atoms or C1 to C20 alkyl groups; and M3 includes alkali metals. Chemical formula 8: In chemical formula 8, R 10 Includes hydrogen atoms or C1 to C20 alkyl groups, Chemical formula 9-1: Chemical formula 9-2: Among them, in chemical formulas 9-1 and 9-2, R 11 They may be the same or different, and each independently includes a hydrogen atom or a C1 to C20 alkyl group; R 12 They may be the same or different, and each independently includes a hydrogen atom or a C1 to C20 alkyl group; L 2 Including *-(C=O)-NR 12 -CH2-* or *-(C=O)-O-*; and L 3 To L 5 Each independently includes a single bond or a C1 to C20 alkylene group.

9. The adhesive according to claim 1, wherein, Based on a total amount of 100 wt% of the linear binder, the seventh structural unit is included in an amount ranging from 30 wt% to 60 wt%, the eighth structural unit is included in an amount ranging from 32 wt% to 55 wt%, and the ninth structural unit is included in an amount ranging from 1 wt% to 15 wt%.

10. The adhesive according to claim 1, wherein, The linear binder also includes a tenth structural unit derived from (C1-C10) alkylene glycol monomers or their salts.

11. The adhesive according to claim 10, wherein, The tenth structural unit is represented by chemical formula 10⁻¹ or chemical formula 10⁻²: Chemical formula 10-1: Chemical formula 10-2: Among them, in chemical formula 10-1 and chemical formula 10-2, M4 includes alkali metals, and n is an integer in the range of 1 to 100.

12. The adhesive according to claim 10, wherein, The tenth structural unit is included in an amount ranging from 0.1 wt% to 15 wt% based on a total amount of 100 wt% of the linear binder.

13. The adhesive according to claim 1, wherein, The weight ratio of the particulate binder to the linear binder in the core-shell structure is in the range of 100:1 to 1:

1.

14. An electrode for a rechargeable lithium battery, the electrode comprising: The adhesive according to any one of claims 1 to 13; as well as Electrode active material.

15. The electrode according to claim 14, wherein, The electrode is a negative electrode.

16. A rechargeable lithium battery, said rechargeable lithium battery comprising: The negative electrode according to claim 15; Positive electrode; as well as Electrolytes.

Images