Copolymer particles, binder composition, slurry and electrode which comprise same, and secondary battery comprising electrode

Abstract

The present invention relates to: copolymer particles; a binder composition, a slurry and an electrode which comprise the copolymer particles; and a secondary battery comprising the electrode, and, more specifically, to: copolymer particles; a binder composition, a slurry and an electrode which comprise the copolymer particles; and a secondary battery comprising the electrode, wherein a cross-linking agent is introduced into a binder, thereby enabling resistance in a battery to be improved and battery lifespan to be extended and output performance to be enhanced.

Description

Copolymer particles, a binder composition containing the same, a slurry, an electrode, and a secondary battery containing the electrode

[0001] The present invention relates to copolymer particles, a binder composition comprising said copolymer particles, a slurry, an electrode, and a secondary battery comprising said electrode.

[0002]

[0003] With the development of IT technologies such as laptops and mobile phones and the increasing demand, as well as the expansion of the electric and hybrid vehicle markets as alternatives to environmental issues and energy shortages, the demand for lithium-ion rechargeable batteries is also rising. Consequently, extensive research is being conducted to improve the performance of lithium-ion rechargeable batteries, including long lifespan, high output, high capacity, high density, and stability.

[0004] This phenomenon is significantly increased in materials such as silicon and tin, which possess high discharge capacities; although the initial charge / discharge capacity is high, the discharge capacity tends to decrease rapidly as the cycle progresses.

[0005] Typical lithium-ion rechargeable batteries use graphite as the negative electrode active material, and recently, there has been an increasing trend in the use of graphite-silicon-based active materials. However, as the process of lithium ions being inserted into the active material during charging and extracted during discharging is repeated, the volume of the active material undergoes expansion and contraction. Consequently, the active material separates from the electrode, leading to a decrease in battery capacity and a reduction in battery life as the cycle progresses.

[0006] Efforts are being made to improve electrode stability and battery performance by preventing this phenomenon by reducing the size of the active material to nano-size or modifying the shape of the active material, and by increasing the adhesion of the binder and suppressing volume expansion with the binder.

[0007] In particular, when using binders, if the adhesive strength of the binder is low, the charge-discharge cycle life of the secondary battery is reduced due to electrode detachment, and problems arise such as the binder acting as a resistor in the secondary battery when non-conductive binders are applied. In addition, while multiple layers of thin-film electrodes are required to secure sufficient battery capacity, this necessitates the use of expensive separators and high-density current collectors, leading to issues regarding cost and volume. Therefore, the need for developing high-adhesion binders is being emphasized to extend the charge-discharge cycle life of the secondary battery, reduce internal resistance by decreasing the amount of binder used, and increase the capacity of the active material.

[0008]

[0009] [Prior Art Literature]

[0010] [Patent Literature]

[0011] (Patent Document 1) Republic of Korea Registered Patent No. 10-1698745

[0012] The present invention aims to provide copolymer particles and a binder composition containing the same, wherein a mixture is formed by polymerizing a mixture containing a soft monomer in an amount of 1.5 parts by weight or more and 3.5 parts by weight or less per 1.0 part by weight of a hard monomer, and the mixture further comprises a crosslinking agent.

[0013] In particular, the present invention aims to provide copolymer particles capable of improving resistance within a battery, extending battery life, and enhancing output performance by introducing a crosslinking agent into a binder.

[0014] In addition, the purpose is to provide copolymer particles and a binder composition containing the same that can produce a secondary battery having a high initial discharge capacity and excellent charge-discharge cycle characteristics, with excellent adhesion between the active material and the metal substrate and / or between the active material, excellent flexibility enabling the production of thick electrodes, and excellent stability and slurry dispersibility in the electrolyte.

[0015] In addition, the present invention aims to provide a slurry and an electrode comprising the copolymer particles, and a secondary battery comprising the electrode.

[0016] However, the problems that this invention seeks to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by a person skilled in the art from the description below.

[0017]

[0018] One aspect of the present invention provides copolymer particles formed by polymerizing a mixture containing a soft monomer in an amount of 1.5 parts by weight or more and 3.5 parts by weight or less per 1.0 part by weight of a hard monomer, said mixture further comprising a crosslinking agent.

[0019] Another aspect of the present invention provides a binder composition comprising the copolymer particles.

[0020] Another aspect of the present invention provides a slurry comprising the copolymer particles and the electrode active material.

[0021] Another aspect of the present invention provides an electrode comprising a current collector and an electrode active material layer comprising copolymer particles formed on the current collector.

[0022] Another aspect of the present invention provides a secondary battery comprising the electrode.

[0023]

[0024] The copolymer particles according to the present invention and the binder composition containing the same can provide copolymer particles capable of improving resistance within a battery, extending the battery's lifespan, and enhancing output performance by introducing a crosslinking agent into the binder.

[0025] In addition, the copolymer particles according to the present invention and the binder composition containing them improve the adhesion between the active material and the metal substrate and / or between the active material, enable the production of a flexible and non-breakable electrode film, and improve stability and slurry dispersibility within the electrolyte, thereby making it possible to secure a secondary battery having a high initial discharge capacity and excellent charge-discharge cycle characteristics.

[0026] In addition, when using copolymer particles with excellent adhesive strength and a binder composition containing them, only a small amount of the binder composition can be used, which can reduce the internal resistance of the secondary battery and increase the capacity of the active material.

[0027]

[0028] The operation and effects of the invention will be described in more detail below through specific embodiments. However, these embodiments are merely examples of the invention and do not define the scope of the invention.

[0029] Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0030] Therefore, it should be understood that the configuration of the embodiments described in this specification is merely one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0032] In the present specification, "a to b" and "a~b" indicating numerical ranges, "to" and "~" are defined as ≥a and ≤b.

[0033] A copolymer particle according to one aspect of the present invention is formed by polymerizing a mixture containing a soft monomer in an amount of 1.5 parts by weight or more and 3.5 parts by weight or less per 1.0 part by weight of a hard monomer, and said mixture may additionally include a crosslinking agent.

[0034] For example, per 1.0 part by weight of the hard monomer, the soft monomer may be 1.5 to 3.0 parts by weight, 1.5 to 2.5 parts by weight, 1.5 to 2.0 parts by weight, 1.7 to 2.5 parts by weight, or 2.0 to 3.0 parts by weight.

[0035] If the weight of the soft monomer per 1.0 weight part of the hard monomer exceeds the range of the present invention, stability and mechanical strength in the electrolyte may be reduced, and if it falls below, dispersibility in the slurry may decrease due to low wettability.

[0036] In one embodiment of the present invention, the copolymer particles may be single particles rather than having a core-shell structure. That is, the copolymer particles may not be manufactured by a seed polymerization method in which a shell is formed on a core particle using a core particle as a seed. If the copolymer particles are not of a core-shell structure manufactured by the seed polymerization method, the process can be simplified because polymerization into single particles is possible without the need to synthesize a seed separately.

[0037] In one embodiment of the present invention, the copolymer particles may contain the crosslinking agent in an amount of more than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of the copolymer particles.

[0038] For example, per 100 parts by weight of the copolymer particles, the crosslinking agent may be 0.06 parts by weight or more and 0.4 parts by weight or less, 0.07 parts by weight or more and 0.4 parts by weight or less, 0.08 parts by weight or more and 0.4 parts by weight or less, 0.07 parts by weight or more and 0.35 parts by weight or less, 0.08 parts by weight or more and 0.35 parts by weight or less, 0.1 parts by weight or more and 0.4 parts by weight or less, 0.1 parts by weight or more and 0.35 parts by weight or less, 0.15 parts by weight or more and 0.4 parts by weight or less, 0.2 parts by weight or more and 0.4 parts by weight or less, or 0.15 parts by weight or more and 0.25 parts by weight or less.

[0039] In one embodiment of the present invention, the crosslinking agent comprises a carbonyl group (-CO-), a vinyl group (-CH=CH2), a methylvinyl group (-CH=C(CH3)2), an ester group (-COO-), and a phosphate group (-OPO3). 2- It may include two or more functional groups selected from the group consisting of ), and sulfone groups (-SO2-).

[0040] For example, the crosslinking agent is divinylbenzene, divinylsulfone, methacrylic anhydride, acrylic anhydride, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, 1,3-butanediol dimethacrylate, bis(4-methacryloylthiophenyl) sulfide, 1,9-bis(acryloyloxy)nonane, or 1,6-hexanediol diacrylate. diacrylate), 1,7-Octadiene-3,5-diol diacrylate, 2,2'-Oxybis(ethyl methacrylate), 1,3-Propanediol diacrylate, Polycaprolactone triacrylate, 1,4-Cyclohexanediol diacrylate, Dipentaerythritol hexacrylate, Ethylene glycol dimethacrylate, Trimethylolpropane trimethacrylate, Propylene glycol Diacrylate (Propylene glycol diacrylate), 1,6-Hexanediol trimethacrylate,Tricyclodecane dimethanol diacrylate, Allyl methacrylate, 1,4-Butanediol trimethacrylate, 1,2-Ethanediol diacrylate, Trimethylolpropane triacrylate, Butyl acrylate-methacrylic acid copolymer, Tetraethylene glycol diacrylate, Diethylene glycol diacrylate, Ethoxylated trimethylolpropane triacrylate, Pentaerythritol triacrylate triacrylate), Polyethylene glycol diacrylate, 2-Hydroxy-3-phenoxypropyl acrylate, Bisphenol A diglycidyl ether diacrylate, 2-Phenoxyethyl acrylate, Bisphenol A ethoxylate diacrylate, Neopentyl glycol diacrylate, 2-Hydroxy-3-phenoxypropyl methacrylate, Bisphenol A propoxylate dimethacrylate,Trimethylolpropane ethoxylate triacrylate, Ethoxylated bisphenol A dimethacrylate, Ethoxylated trimethylolpropane trimethacrylate, Di(pentaerythritol) hexaacrylate, Polyethylene glycol dimethacrylate, Tetrahydrofurfuryl acrylate, 1,3-Butanediol diacrylate, Propoxylated glycerol triacrylate, Pentaerythritol triacrylate, Dipentaerythritol pentaacrylate, 1,10-Decanediol diacrylate, Bis(2-(methacryloyloxy)ethyl) phosphate, 1,12-Dodecanediol diacrylate, 1,5-Pentanediol diacrylate, Glycerol ethoxylate triacrylate, Trimethylolpropane tris(2-ethylhexanoate), Bis(4-methacryloyloxyphenyl) methane (Bis(4-methacryloyloxyphenyl)methane),It may be di(trimethylolpropane) tetraacrylate, 2,2,4-trimethyl-1,3-pentanediol diacrylate, isobornyl acrylate, bisphenol A glycerolate dimethacrylate, 1,4-butanediol diacrylate, or a combination thereof.

[0041] In one embodiment of the present invention, the copolymer particles may comprise a hard monomer and a soft monomer as polymerization units, and may comprise a copolymer particle crosslinked with a crosslinking agent, wherein the soft monomer is included in an amount of 1.5 parts by weight or more and 3.5 parts by weight or less per 1.0 part by weight of the hard monomer.

[0042] In one embodiment of the present invention, the soft monomer may include a monomer having a glass transition temperature (Tg) of less than 25 ℃, and the hard monomer may include a monomer having a glass transition temperature (Tg) of 15 ℃ or higher.

[0043] For example, the soft monomer may include a monomer with a glass transition temperature of less than 20°C, and the hard monomer may include a monomer with a glass transition temperature of 20°C or higher.

[0044] In one embodiment of the present invention, the soft monomer may include one or more monomers selected from the group consisting of conjugated diene monomers and (meth)acrylic acid ester monomers, and the hard monomer may include one or more monomers selected from the group consisting of styrene monomers, (meth)acrylic acid ester monomers, (meth)acrylonitrile monomers and (meth)acrylamide monomers.

[0045] The above conjugated diene monomer may include one or more monomers selected from the group consisting of 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and 1,3-pentadiene, but is not limited thereto.

[0046] The above (meth)acrylic acid ester monomer may include one or more monomers selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-hexyl acrylate, 2-hexyl methacrylate, n-amyl acrylate, isoamyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, lauryl methacrylate, and itaconic acid, but is not limited thereto.

[0047] At this time, the (meth)acrylic acid ester-based monomer described as an example of the above soft monomer may represent both acrylic acid ester-based monomers and methacrylic acid ester-based monomers.

[0048] The above styrene-based monomer may include one or more monomers selected from the group consisting of α-methylstyrene, β-methylstyrene, pt-butylstyrene, and divinylbenzene, but is not limited thereto.

[0049] The above (meth)acrylic acid ester monomer may include one or more monomers selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, isobornyl acrylate, isovinyl acrylate, isovinyl methacrylate, and itaconic acid, but is not limited thereto.

[0050] The above (meth)acrylonitrile-based monomer may include acrylonitrile or methacrylonitrile, but is not limited thereto.

[0051] The above (meth)acrylamide-based monomer may include one or more monomers selected from acrylamide, methacrylamide, n-methylolacrylamide, and n-butoxymethylacrylamide, but is not limited thereto.

[0052] At this time, the (meth)acrylic acid ester-based monomer described as an example of the above-mentioned hard monomer may represent both an acrylic acid ester-based monomer and a methacrylic acid ester-based monomer.

[0053] At this time, the (meth)acrylonitrile-based monomer described as an example of the above-mentioned hard monomer may represent both acrylonitrile-based monomers and methacrylonitrile-based monomers.

[0054] At this time, the (meth)acrylamide-based monomer described as an example of the hard monomer above may represent both acrylamide-based monomer and methacrylamide-based monomer.

[0055] In one embodiment of the present invention, the glass transition temperature (Tg) of the copolymer particles may be -50 ℃ to 10 ℃.

[0056] For example, the glass transition temperature (Tg) of the copolymer particles may be -45 ℃ to 10 ℃, -43 ℃ to 10 ℃, -40 ℃ to 10 ℃, -45 ℃ to 7 ℃, -45 ℃ to 5 ℃, -43 ℃ to 7 ℃, or -43 ℃ to 5 ℃, or -40 ℃ to 5 ℃.

[0057] The above copolymer particles have a low glass transition temperature (Tg) of -50°C to 10°C, and because they are hydrophobic compared to copolymers used as binders in conventional batteries, migration is suppressed and the film formation speed is fast, resulting in high adhesion.

[0058] In addition, since the copolymer particles are highly crosslinked, they have high elasticity and excellent adhesion, as well as excellent flexibility due to their low glass transition temperature (Tg). Therefore, the copolymer particles can be used in the production of thick electrodes.

[0059] If the glass transition temperature (Tg) of the copolymer particles exceeds the range of the present invention, a decrease in adhesion between the active material and the metal substrate and / or between the active material may occur, and if it falls below, the stability of the electrode coating may decrease.

[0060] In one embodiment of the present invention, the average particle size of the copolymer particles may be 15 nm to 550 nm.

[0061] For example, the average particle size of the copolymer particles may be 20 nm to 500 nm, 25 nm to 400 nm, 30 nm to 300 nm, 35 nm to 250 nm, 40 nm to 200 nm, 20 nm to 100 nm, 100 nm to 150 nm, 150 nm to 200 nm, 200 nm to 250 nm, 250 nm to 300 nm, 300 nm to 350 nm, 350 nm to 400 nm, 400 nm to 450 nm, or 450 nm to 500 nm.

[0062] If the average particle size of the copolymer particles exceeds the range of the present invention, electrode processability may be reduced, and if it falls below, a decrease in adhesion between the active material and the metal substrate and / or between the active material may occur.

[0063] In one embodiment of the present invention, the degree of gelation measured by solidifying the binder containing the copolymer particles may be 80% or more and 99% or less.

[0064] For example, the degree of gelation may be 85% or more and 99% or less.

[0065] At this time, the degree of gelation measures the extent to which the solidified binder containing the copolymer particles does not leach out in the solvent. For example, the solvent may be tetrahydrofuran (THF).

[0066] In one embodiment of the present invention, the acidity of the binder solution containing the copolymer particles may be pH 3 or higher and pH 9 or lower.

[0067] For example, the above acidity may be pH 4 or higher and pH 8 or lower.

[0068] In one embodiment of the present invention, the degree of electrolyte swelling, which is the ratio of the increased weight of the film to the weight of the film after the film made of the copolymer particles is immersed in the electrolyte and left at 60°C for 72 hours, may be 35% or more and 48% or less.

[0069] For example, the degree of swelling of the electrolyte may be 35% or more and 45% or less, 35% or more and 43% or less, 35% or more and 41% or less, 38% or more and 45% or less, or 38% or more and 41% or less.

[0070] In this case, the film may be manufactured solely from the copolymer particles. That is, the film may be composed of the copolymer particles.

[0071] In one embodiment of the present invention, the mixture may include an emulsifier, and the content of the emulsifier may be 1 to 10 parts by weight per 100 parts by weight of the first monomer mixture. In addition, a surfactant may be used as the emulsifier, and the surfactant may be anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants, and preferably, anionic surfactants may be used.

[0072] Specific examples of the above-mentioned anionic surfactants include, but are not limited to, alkali salts of higher fatty acids, N-acryl amino acids, alkyl ether carbonates, acylated peptides, alkyl sulfonates, alkylbenzenes, alkyl amino acids, alkyl naphthalene sulfonates, sulfosuccinates, sulfated oils, alkyl sulfates, alkyl ether sulfates, alkyl aryl ether sulfates, alkyl amide sulfates, alkyl phosphates, alkyl ethriphosphates, and alkyl aryl ether triphosphates, and preferably, sodium dodecylbenzene sulfonate may be used.

[0073] In one embodiment of the present invention, the mixture may include an initiator, and the content of the initiator may be 0.1 to 10 parts by weight per 100 parts by weight of the first monomer mixture, preferably 0.2 to 5 parts by weight, but is not limited thereto as long as it is sufficient to achieve the function of initiating polymerization.

[0074] A binder composition according to one aspect of the present invention may include any one of the copolymer particles.

[0075] A slurry according to one aspect of the present invention may include any one of the copolymer particles and an electrode active material.

[0076] In one embodiment of the present invention, the slurry may include organic solvents such as carboxymethylcellulose, NMP (N-methylpyrrolidone), DMF (dimethylformamide), acetone, dimethylacetamide, or water as a solvent, and preferably, carboxymethylcellulose may be used. In addition, the slurry may include one or more solvents.

[0077] The above carboxymethylcellulose may have a degree of substitution of hydroxyl (-OH) groups by carboxymethyl groups (-CH2CO2H) of 0.7 to 1.2, a molecular weight (Mn) of 500,000 to 900,000, and a pH of 6.5 to 8.0.

[0078] In one embodiment of the present invention, the slurry may contain the copolymer particles in an amount of 0.1% to 10% by weight per 100% by weight of the slurry. For example, the slurry may contain the copolymer particles in an amount of 0.1% to 8% by weight, 0.1% to 6% by weight, 0.1% to 4% by weight, or 0.1% to 3% by weight per 100% by weight of the slurry. Additionally, the slurry may include carboxymethylcellulose (CMC) and an electrode active material capable of intercalation and deintercalation of lithium ions.

[0079] For example, the above slurry may be an anode slurry, a cathode slurry, or a combination thereof.

[0080] An electrode according to one aspect of the present invention may include a current collector and an electrode active material layer comprising copolymer particles formed on the current collector.

[0081] For example, the electrode may be an anode, a cathode, or a combination thereof.

[0082] In one embodiment of the present invention, the adhesion strength of a cathode using a cathode slurry containing the copolymer particles may be 24.5 gf / cm or higher. For example, it may be 24.5 gf / cm or higher and 30 gf / cm or lower, 24.5 gf / cm or higher and 28 gf / cm or lower, or 24.5 gf / cm or higher and 26 gf / cm or lower.

[0083] In one embodiment of the present invention, the current collector is a part where electron movement occurs in the electrochemical reaction of the active material, and depending on the type of electrode, there are negative current collectors and positive current collectors. The current collector may form fine irregularities on its surface to strengthen the bonding force of the electrode active material, and can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

[0084] The above negative current collector can generally be formed with a thickness of 5 μm to 30 μm. Such a negative current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, 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 may be used.

[0085] The above positive current collector can generally be formed with a thickness of 3 μm to 500 μm. The above positive current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. may be used.

[0086] In one embodiment of the present invention, the electrode active material is a material capable of causing an electrochemical reaction and is used in the manufacture of cathode and anode slurries, and depending on the type of electrode, there is a cathode active material and an anode active material.

[0087] The above-mentioned negative electrode active material may be selected from one or more of the group consisting of carbon and graphite materials capable of intercalation and deintercalation of lithium ions, Si-based materials, metals and compounds capable of alloying with lithium, composites of metals and their compounds with carbon and graphite materials, lithium-containing nitrides, etc.

[0088] Carbon and graphite materials include natural graphite, synthetic graphite, expanded graphite, carbon fiber, non-graphitizable carbon, carbon black, carbon nanotubes, fullerene, activated carbon, hard carbon, and soft carbon. Si-based materials include Si and SiO. x (0 <x<2), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 또는 이들의 조합이다.), Si-C 복합체 또는 이들의 조합의 Si계 화합물 등이 있다. 리튬과 합금이 가능한 금속 및 원소로는 Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt, Ti 등이 있다. 상기 음극 슬러리는 상기 음극 활물질을 상기 음극 슬러리 100 중량부에 대하여 20 내지 80중량부의 함량으로 포함할 수 있다.

[0089] As for the above positive active material, a lithium transition metal oxide represented by the above chemical formula 1 may be used alone, or in some cases, other positive active materials capable of absorbing and releasing lithium ions may be mixed and used.

[0090] For example, the above-mentioned positive active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; chemical formula Li1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7, etc.; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (where M is Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y = 0.01 to 0.3); chemical formula LiMn 2-y Lithium manganese complex oxides represented by MyO2 (where M = Co, Ni, Fe, Cr, Zn or Ta and y = 0.01 to 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu or Zn); LiMn2O4 in which part of the Li of the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. may be used, but are not limited to these.

[0091] The above positive active material is preferably Li a Ni x Mn y Co z Chemical formula 1 of O2 (wherein, 0.8≤a<1.2, 0.2≤x<1, 0 <y<1, 0<z<1, x+y+z=1이다)로 표시되는 리튬 니켈-망간 코발트 산화물 및 LiCoO2를 포함할 수 있다. 상기 화학식 1로 표시되는 리튬 전이금속 산화물은 높은 방전 용량을 나타내는 바, 전체 양극 활물질에 대하여 적어도 20 중량 % 이상의 함량으로 포함되어 있는 것이 바람직하고, 더욱 바람직하게는 20 중량 % 내지 90 중량 %로 포함될 수 있다. LiCoO2는 양극 활물질 전체 중량을 기준으로 20 중량 % 내지 80 중량 %로 포함될 수 있다.

[0092] A secondary battery according to one aspect of the present invention may include the electrode.

[0093] In one embodiment of the present invention, the internal resistance of the secondary battery including a cathode using a cathode slurry containing the copolymer particles may be 265 mΩ or less.

[0094] For example, the internal resistance of the above secondary battery may be 210 mΩ or more and 265 mΩ or less, 215 mΩ or more and 265 mΩ or less, 220 mΩ or more and 260 mΩ or less, 210 mΩ or more and 250 mΩ or less, 210 mΩ or more and 230.5 mΩ or less, or 221 mΩ or more and 231 mΩ or less. That is, in the case of a secondary battery manufactured using copolymer particles in which the crosslinking agent content range satisfies the range of the present invention, excellent adhesion between the active material and the metal substrate and / or between the active material is achieved even with the use of a smaller amount of copolymer particles, and there is an effect of reducing the internal resistance value of the battery measured through DC-IR.

[0095] In one embodiment of the present invention, the capacity retention rate of the secondary battery comprising a cathode using a cathode slurry comprising the copolymer particles may be 95% or higher. For example, the capacity retention rate of the secondary battery may be 95% or higher and 99% or lower, or 96% or higher and 98% or lower.

[0096] In one embodiment of the present invention, the secondary battery may include a separator. The separator may be an insulating thin film having high ion permeability and mechanical strength, interposed between the positive electrode and the negative electrode. The pore diameter of the separator may generally be 0.01 μm to 10 μm, and the thickness may generally be 5 μm to 300 μm. For example, an olefin-based polymer such as chemically resistant and hydrophobic polypropylene; a sheet or nonwoven fabric made of glass fiber or polyethylene, etc. may be used as such a separator. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as the separator.

[0097] The above lithium salt-containing non-aqueous electrolyte consists of an electrolyte and a lithium salt, and the electrolyte may be a non-aqueous organic solvent, an organic solid electrolyte, an inorganic solid electrolyte, etc.

[0098] As the above-mentioned non-aqueous organic solvent, for example, aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfranc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, methyl propionate, ethyl propionate, etc. may be used.

[0099] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing an ionic dissociator, etc.

[0100] As the above-mentioned inorganic solid electrolyte, for example, nitrides, halides, and sulfates of Li such as Li3N, LiI, Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, Li4SiO4, Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2 may be used.

[0101] The above lithium salt is a substance that dissolves well in the above-mentioned non-aqueous electrolyte, for example, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl10 LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (CF3SO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium tetraphenylborate, imide, etc. may be used.

[0102] In addition, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., the electrolyte may also be supplemented with, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride, etc. In some cases, to impart non-flammability, halogen-containing solvents such as carbon tetrachloride and trifluoroethylene may be further included, and carbon dioxide may be further included to improve high-temperature preservation characteristics, and fluoro-ethylene carbonate (FEC), propene sultone (PRS), fluoro-propylene carbonate (FPC), ethylene carbonate (EC), ethyl methyl carbonate, diethyl carbonate, etc. may be further included.

[0103] In one embodiment of the present invention, the secondary battery can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells used as a power source for a medium-to-large device.

[0104] Preferred examples of the above medium-to-large devices include, but are not limited to, power tools that are powered by an electric motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); and electric golf carts.

[0105]

[0106] The present invention will be explained in more detail below through examples. However, the following examples are intended to explain the invention more specifically, and the scope of the invention is not limited by the following examples.

[0107]

[0108] Examples and Comparative Examples: Preparation of Copolymer Particles

[0109] [Example 1]

[0110] To 200 g of distilled water, 60 g of 1,3-butadiene as a soft monomer, 30 g of styrene as a hard monomer, 3 g of itaconic acid, 7 g of methyl methacrylate, and 0.5 g of acrylonitrile, and 0.2 g of divinylbenzene as a crosslinking agent were added.

[0111] Subsequently, 0.5 g of sodium dodecylbenzene sulfonate was added as a surfactant, emulsified, and stirred. Then, 1 g of potassium sulfite, a decomposition initiator, was added to proceed with the polymerization reaction to produce copolymer particles.

[0112]

[0113] [Example 2]

[0114] Copolymer particles were prepared in the same manner as in Example 1, except that 0.3 g of divinylbenzene was added as a crosslinking agent.

[0115]

[0116] [Example 3]

[0117] Copolymer particles were prepared in the same manner as in Example 1, except that 0.1 g of divinylbenzene was added as a crosslinking agent.

[0118]

[0119] [Comparative Example 1]

[0120] Copolymer particles were prepared in the same manner as in Example 1 above, except that divinylbenzene was not added as a crosslinking agent.

[0121]

[0122] [Comparative Example 2]

[0123] Copolymer particles were prepared in the same manner as in Example 1, except that 0.05 g of divinylbenzene was added as a crosslinking agent.

[0124]

[0125] [Comparative Example 3]

[0126] Copolymer particles were prepared in the same manner as in Example 1, except that 0.5 g of divinylbenzene was added as a crosslinking agent.

[0127]

[0128] [Comparative Example 4]

[0129] Copolymer particles were prepared in the same manner as in Example 1, except that 1 g of divinylbenzene was added as a crosslinking agent.

[0130]

[0131] Preparation Example: Preparation of cathode slurry, cathode, and battery

[0132] A cathode slurry was prepared by mixing 97 parts by weight of graphite as a cathode active material, 1.8 parts by weight of copolymer particles of Examples 1 to 3 and Comparative Examples 1 to 4, and 1.2 parts by weight of carboxymethylcellulose with distilled water.

[0133] The above cathode slurry was uniformly coated onto a Cu thin film with a thickness of 10 μm using an applicator, and then dried at a temperature of 100°C for 30 minutes to produce a cathode.

[0134] A positive electrode was prepared by mixing lithium nickel-manganese cobalt oxide as the positive active material, acetylene black as the conductive material, and polyvinylidene fluoride (PVDF) as the positive binder in a weight ratio of 92:4:4 and coating the mixture onto an aluminum collector. An electrolyte was prepared by dissolving LiPF6 to a concentration of 1M in a non-aqueous solvent having a composition of ethylene carbonate (EC):ethylmethyl carbonate (EMC):diethyl carbonate (DEC) = 1:2:1. A full cell was prepared using a porous polyethylene film as the separator.

[0135] Table 1 below shows the types of copolymer particles used.

[0136] Type of copolymer particles Preparation Example 1 Example 1 Preparation Example 2 Example 2 Preparation Example 3 Example 3 Comparative Preparation Example 1 Comparative Example 1 Comparative Preparation Example 2 Comparative Example 2 Comparative Preparation Example 3 Comparative Example 3 Comparative Preparation Example 4 Comparative Example 4

[0137]

[0138] [Evaluation Example]

[0139] Evaluation Example 1: Measurement of Electrolyte Swelling Degree (%)

[0140] 0.6 g of copolymer particles of Examples 1 to 3 and Comparative Examples 1 to 4 were dried in an oven at a temperature of 120 ℃ to form a film, then immersed in an electrolyte, sealed, and left at a temperature of 60 ℃ for 72 hours.

[0141] Afterwards, the film was removed from the electrolyte, the electrolyte on the surface of the film was wiped off, and the increased weight of the film was measured.

[0142] The weight of the film before immersion in the electrolyte and the weight of the film after immersion in the electrolyte and leaving it at 60°C for 72 hours were compared to calculate the increased weight ratio of the film (electrolyte swelling degree (%)).

[0143] The calculated electrolyte swelling degree (%) is shown in Table 2 below.

[0144] Electrolyte Swelling Degree (%) Example 140% Example 241% Example 338% Comparative Example 130% Comparative Example 232% Comparative Example 350% Comparative Example 452%

[0145]

[0146] As a result of measurement, it was confirmed that the electrolyte swelling degree (%) of the films prepared using the binder composition containing the copolymer particles of Examples 1 to 3 was 40%, 41%, and 38%, respectively, which is higher than the electrolyte swelling degree (%) of the film prepared using the binder composition containing the copolymer particles of Comparative Example 1, which did not have a crosslinking agent added.

[0147] Through this, it was confirmed that when a crosslinking agent is added during the preparation of copolymer particles, the degree of electrolyte swelling (%) of the film prepared using a binder composition containing copolymer particles increases.

[0148] On the other hand, it was confirmed that the electrolyte swelling degree (%) of a film prepared using a binder composition containing copolymer particles of Comparative Example 2, in which the crosslinking agent was added at 0.05 parts by weight per 100 parts by weight of copolymer particles, was not significantly different from the electrolyte swelling degree (%) of a film prepared using a binder composition containing copolymer particles of Comparative Example 1, in which no crosslinking agent was added. In other words, it was confirmed that there was no significant difference in the electrolyte swelling degree (%) when the crosslinking agent content was below the range of the present invention.

[0149] In addition, it was confirmed that the electrolyte swelling degree (%) of a film prepared using a binder composition containing copolymer particles of Comparative Example 3 or 4, in which 0.5 parts by weight or 1 part by weight of the crosslinking agent was added per 100 parts by weight of copolymer particles, was higher than that of a film prepared using a binder composition containing copolymer particles of Examples 1 to 3.

[0150]

[0151] Evaluation Example 2: Measurement of cathode adhesion strength

[0152] The cathodes of Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4, prepared using the copolymer particles of Examples 1 to 3 and Comparative Examples 1 to 4, were cut to a size of 25 mm in width and 100 mm in length. A double-sided tape with an area of ​​20 mm in width and 40 mm in length was attached to an acrylic plate with an area of ​​40 mm in width and 100 mm in length. After attaching the prepared electrode to the double-sided tape, it was lightly pressed 5 times with a hand roller. It was then mounted on a UTM (20 kgf Load cell) to peel off approximately 25 mm of one side of the cathode. The cathode was then fixed to the upper clip of the tensile strength tester, and the tape attached to one side of the cathode was fixed to the lower clip. The force of the electrode falling in the 180° direction was measured while peeling at a speed of 100 mm / min. At least 5 specimens were prepared and measured per sample, and the average value was calculated; the results are shown in Table 3.

[0153] Adhesion strength (gf / cm) Preparation Example 1 25.1 Preparation Example 2 24.8 Preparation Example 3 26.0 Comparative Preparation Example 1 24.2 Comparative Preparation Example 2 23.3 Comparative Preparation Example 3 17.1 Comparative Preparation Example 4 15.8

[0154]

[0155] As a result of measurement, as shown in Table 3, it was confirmed that the cathodes of Preparation Examples 1 to 3, prepared by including the copolymer particles of Examples 1 to 3, had a high adhesion strength of 24.8 gf / cm or higher. That is, in the case of the cathodes of Preparation Examples 1 to 3, prepared by including the copolymer particles of Examples 1 to 3, it was confirmed that they had a higher adhesion strength when compared to the cathodes of Comparative Preparation Examples 1 to 4, prepared by including the copolymer particles of Comparative Examples 1 to 4.

[0156] In particular, the cathodes of Comparative Examples 3 and 4, prepared by including copolymer particles of Comparative Examples 3 and 4 in which the crosslinking agent content range exceeds the range of the present invention, showed reduced adhesion compared to the cathode of Comparative Example 1, prepared by including copolymer particles of Comparative Example 1, in which no crosslinking agent was added. The cathode of Comparative Example 2, prepared by including copolymer particles of Comparative Example 2 in which the crosslinking agent content range falls below the range of the present invention, showed slightly reduced adhesion compared to the cathode of Comparative Example 1, prepared by including copolymer particles of Comparative Example 1, in which no crosslinking agent was added.

[0157] That is, it was confirmed that the adhesion of the cathodes of Preparation Examples 1 to 3, which are prepared by including the copolymer particles of Examples 1 to 3, which contain a crosslinking agent in an amount of more than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of copolymer particles, is excellent.

[0158] This means that when the crosslinking agent content satisfies the range of the present invention, a cathode having superior adhesion between the active material and the metal substrate can be obtained.

[0159]

[0160] Evaluation Example 3: Measurement of battery capacity retention rate

[0161] For the batteries prepared in Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4, two charge-discharge cycles were performed at 25°C with a charge-discharge current density of 0.1C, a charge termination voltage of 4.2V, and a discharge stop voltage of 2.8V.

[0162] Afterwards, 100 charge-discharge cycles were performed with a charge-discharge current density of 1C, a charge termination voltage of 4.2V, and a discharge termination voltage of 2.8V.

[0163] All discharges were performed under constant current / constant voltage conditions, and the termination current of the constant voltage discharge was set to 0.005C.

[0164] At this time, the capacity retention rate was calculated according to the following mathematical formula 1.

[0165]

[0166] <Mathematical Formula 1>

[0167] Capacity retention rate [%] = [Discharge capacity of the 100th cycle / Discharge capacity of the 1st cycle] x 100

[0168]

[0169] The results of measuring the capacity retention rate of the batteries prepared in Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4 are shown in Table 4.

[0170] Volume Retention Rate (%, @100 cycles) Preparation Example 197.5 % Preparation Example 297.6 % Preparation Example 396.8 % Comparative Preparation Example 193.8 % Comparative Preparation Example 294.2 % Comparative Preparation Example 394.6 % Comparative Preparation Example 492.3 %

[0171]

[0172] As a result of measurement, as shown in Table 4, it was confirmed that the batteries of Preparation Examples 1 to 3, prepared by including the copolymer particles of Examples 1 to 3, had a high capacity retention rate of 96.8% or higher.

[0173] That is, in the case of the batteries of Manufacturing Examples 1 to 3 prepared including the copolymer particles of Examples 1 to 3, it was confirmed that they had a higher capacity retention rate when compared to the batteries of Comparative Manufacturing Examples 1 to 4 prepared including the copolymer particles of Comparative Examples 1 to 4.

[0174] In particular, the batteries of Comparative Examples 3 and 4, which were prepared by including copolymer particles of Comparative Examples 3 and 4 in which the crosslinking agent content range exceeded the range of the present invention, showed a decrease in capacity retention rate as the crosslinking agent content increased.

[0175] Meanwhile, the battery of Comparative Example 2, which was prepared by including copolymer particles of Comparative Example 2 in which the crosslinking agent content range was lower than that of the present invention, showed a slightly increased capacity retention rate compared to the battery of Comparative Example 1, which was prepared by including copolymer particles of Comparative Example 1 in which no crosslinking agent was added.

[0176] That is, it was confirmed that the capacity retention rate of the batteries of Preparation Examples 1 to 3, which are prepared by including the copolymer particles of Examples 1 to 3, which contain a crosslinking agent in an amount of more than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of copolymer particles, is excellent.

[0177] This means that when the crosslinking agent content satisfies the range of the present invention, a battery with superior lifespan characteristics and output performance can be obtained.

[0178]

[0179] Evaluation Example 4: Measurement of internal resistance of a battery

[0180] After the initial formation of the batteries prepared in Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4, the internal resistance of the batteries was measured using the DC-IR (Direct Current Internal Resistance) method under the condition that they were charged at a rate of 0.3C at a voltage corresponding to 50% of the SOC in CC / CV mode and discharged at a rate of 2C at 2.75V. At this time, the temperature of the chamber was 25 ℃.

[0181]

[0182] The results of measuring the internal resistance of the batteries prepared in Preparation Examples 1 to 3 and Comparative Preparation Examples 1 to 4 are shown in Table 5.

[0183] Internal Resistance (DC-IR, mΩ) Preparation Example 1 225.3 Preparation Example 2 221.1 Preparation Example 3 230.2 Comparative Preparation Example 1 313.7 Comparative Preparation Example 2 300.4 Comparative Preparation Example 3 265.6 Comparative Preparation Example 4 284.1

[0184]

[0185] As a result of measurement, as shown in Table 5, it was confirmed that the batteries of Preparation Examples 1 to 3, prepared by including the copolymer particles of Examples 1 to 3, had a low internal resistance of 230.2 mΩ or less.

[0186] That is, in the case of the batteries of Manufacturing Examples 1 to 3 prepared including the copolymer particles of Examples 1 to 3, it was confirmed that they had lower internal resistance values ​​when compared to the battery of Comparative Manufacturing Example 1 prepared including the copolymer particles of Comparative Example 1 without the addition of a crosslinking agent.

[0187] In particular, in the case of the batteries of Manufacturing Examples 1 to 3 prepared including the copolymer particles of Examples 1 to 3, it was confirmed that they had lower internal resistance values ​​when compared to the batteries of Comparative Examples 2 to 4 prepared including the copolymer particles of Comparative Examples 3 and 4, in which the crosslinking agent content range exceeded the range of the present invention, or the copolymer particles of Comparative Example 2, in which the crosslinking agent content range fell below the range of the present invention.

[0188] That is, it was confirmed that the resistance performance of the batteries of Preparation Examples 1 to 3, which are prepared by including the copolymer particles of Examples 1 to 3, which contain a crosslinking agent in an amount of more than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of copolymer particles, was improved. This is presumed to be due to the increase in the electrolyte swelling degree (%) of the film prepared using the binder composition containing the copolymer particles when a crosslinking agent is added within the scope of the present invention during the preparation of copolymer particles.

[0189] This means that when the crosslinking agent content satisfies the range of the present invention, a battery of excellent performance with reduced power loss due to internal resistance can be obtained.

[0190]

[0191] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0192]

[0193] The copolymer particles according to the present invention and the binder composition containing the same can provide copolymer particles capable of improving resistance within a battery, extending the battery's lifespan, and enhancing output performance by introducing a crosslinking agent into the binder.

[0194] In addition, the copolymer particles according to the present invention and the binder composition containing them improve the adhesion between the active material and the metal substrate and / or between the active material, enable the production of a flexible and non-breakable electrode film, and improve stability and slurry dispersibility within the electrolyte, thereby making it possible to secure a secondary battery having a high initial discharge capacity and excellent charge-discharge cycle characteristics.

[0195] In addition, when using copolymer particles with excellent adhesive strength and a binder composition containing them, only a small amount of the binder composition can be used, which can reduce the internal resistance of the secondary battery and increase the capacity of the active material.

Claims

1. A mixture is polymerized to be formed in which a soft monomer is included in an amount of 1.5 parts by weight or more and 3.5 parts by weight or less per 1.0 part by weight of a hard monomer, and The above mixture further comprises a crosslinking agent, Copolymer particles.

2. In Paragraph 1, A crosslinking agent containing more than 0.05 parts by weight and less than or equal to 0.4 parts by weight per 100 parts by weight of the copolymer particles, Copolymer particles.

3. In Paragraph 1, The above crosslinking agent consists of a carbonyl group (-CO-), a vinyl group (-CH=CH2), a methylvinyl group (-CH=C(CH3)2), an ester group (-COO-), and a phosphate group (-OPO3). 2- Comprising two or more functional groups selected from the group consisting of ), and sulfone groups (-SO2-), Copolymer particles.

4. In Paragraph 1, The above crosslinking agents are divinylbenzene, divinylsulfone, methacrylic anhydride, acrylic anhydride, 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol, 1,3-butanediol dimethacrylate, bis(4-methacryloylthiophenyl) sulfide, 1,9-bis(acryloyloxy)nonane, and 1,6-hexanediol diacrylate. 1,7-Octadiene-3,5-diol diacrylate, 2,2'-Oxybis(ethyl methacrylate), 1,3-Propanediol diacrylate, Polycaprolactone triacrylate, 1,4-Cyclohexanediol diacrylate, Dipentaerythritol hexacrylate, Ethylene glycol dimethacrylate, Trimethylolpropane trimethacrylate, Propylene glycol diacrylate (Propylene glycol diacrylate), 1,6-Hexanediol trimethacrylate, Tricyclodecane dimethanol diacrylate,Allyl methacrylate, 1,4-Butanediol trimethacrylate, 1,2-Ethanediol diacrylate, Trimethylolpropane triacrylate, Butyl acrylate-methacrylic acid copolymer, Tetraethylene glycol diacrylate, Diethylene glycol diacrylate, Ethoxylated trimethylolpropane triacrylate, Pentaerythritol triacrylate, Polyethylene glycol diacrylate, 2-Hydroxy-3-phenoxypropyl acrylate, Bisphenol A diglycidyl ether diacrylate, 2-phenoxyethyl acrylate, Bisphenol A ethoxylate diacrylate, Neopentyl glycol diacrylate, 2-Hydroxy-3-phenoxypropyl methacrylate, Bisphenol A propoxylate dimethacrylate,Trimethylolpropane ethoxylate triacrylate, Ethoxylated bisphenol A dimethacrylate, Ethoxylated trimethylolpropane trimethacrylate, Di(pentaerythritol) hexaacrylate, Polyethylene glycol dimethacrylate, Tetrahydrofurfuryl acrylate, 1,3-Butanediol diacrylate, Propoxylated glycerol triacrylate, Pentaerythritol triacrylate, Dipentaerythritol pentaacrylate, 1,10-Decanediol diacrylate, Bis(2-(methacryloyloxy)ethyl) phosphate, 1,12-Dodecanediol diacrylate, 1,5-Pentanediol diacrylate, Glycerol ethoxylate triacrylate, Trimethylolpropane tris(2-ethylhexanoate), Bis(4-methacryloyloxyphenyl) methane (Bis(4-methacryloyloxyphenyl)methane),Di(trimethylolpropane) tetraacrylate, 2,2,4-trimethyl-1,3-pentanediol diacrylate, isobornyl acrylate, bisphenol A glycerolate dimethacrylate, 1,4-butanediol diacrylate, or a combination thereof, Copolymer particles.

5. In Paragraph 1, The above soft monomer includes a monomer having a glass transition temperature (Tg) of less than 25 ℃, and The above-mentioned hard monomer comprises a monomer having a glass transition temperature (Tg) of 15 ℃ or higher, Copolymer particles.

6. In Paragraph 1, The above soft monomer comprises one or more monomers selected from the group consisting of conjugated diene monomers and (meth)acrylic acid ester monomers, and The above light monomer comprises one or more monomers selected from the group consisting of styrene-based monomers, (meth)acrylic acid ester-based monomers, (meth)acrylonitrile-based monomers, and (meth)acrylamide-based monomers. Copolymer particles.

7. In Paragraph 1, A glass transition temperature of -50 ℃ to 10 ℃, Copolymer particles.

8. In Paragraph 1, having an average particle size of 15 nm to 550 nm, Copolymer particles.

9. In Paragraph 1, An electrolyte swelling degree of 35% or more and 48% or less, wherein the weight of the film after immersing the film prepared from the above copolymer particles in the electrolyte and leaving it at 60°C for 72 hours is compared to the weight of the film before immersion in the electrolyte, which is the ratio of the increased weight of the film. Copolymer particles.

10. A copolymer particle comprising any one of claims 1 to 9, Binder composition.

11. A copolymer particle of any one of claims 1 to 9; and Electrode active material; comprising, Slurry.

12. The whole house; and An electrode active material layer formed on the above-mentioned current collector and comprising copolymer particles of any one of claims 1 to 9; comprising, electrode.

13. Including the electrode of claim 12, Secondary battery.