Lithium secondary battery

Abstract

Provided is a lithium secondary battery comprising: an electrode plate including an active material for a lithium secondary battery, a binder, and a first additive of chemical formula 1; and an electrolyte, wherein the electrolyte includes a non-aqueous organic solvent, a lithium salt and an additive, the additive including a second additive represented by chemical formula 2.

Description

lithium secondary battery

[0001] This is about lithium secondary batteries.

[0002]

[0003] Recently, accompanied by the rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for high-energy-density, high-capacity rechargeable batteries is rapidly increasing. Accordingly, research and development to improve the performance of lithium-ion batteries is actively underway.

[0004] A lithium secondary battery is a battery comprising a positive electrode and a negative electrode containing an active material capable of lithium ion intercalation and deintercalation, and an electrolyte, which produces electrical energy through oxidation and reduction reactions when lithium ions are intercalated or deintercalated from the positive and negative electrodes.

[0005] The electrolyte for lithium secondary batteries consists of a lithium salt dissolved in a non-aqueous organic solvent. The characteristics of a lithium secondary battery are determined by complex reactions between the anode and the electrolyte, and between the cathode and the electrolyte. Therefore, the use of an appropriate electrolyte is one of the important variables for improving the performance of a lithium secondary battery. In particular, since the reactions between the anode and the electrolyte, as well as between the cathode and the electrolyte, are critical, the selection of the electrolyte according to the anode and cathode is important.

[0006]

[0007] One embodiment provides a lithium secondary battery that provides a high capacity recovery rate, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect after high-temperature storage.

[0008] One embodiment provides a lithium secondary battery that offers low initial resistance, a high capacity recovery rate after high-temperature storage, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect.

[0009] One embodiment provides a lithium secondary battery comprising a electrode plate containing a first additive of Formula 1, which provides a high capacity recovery rate, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect after high-temperature storage.

[0010] One embodiment provides a lithium secondary battery comprising a electrode plate containing a first additive of Formula 1, which provides low initial resistance, high capacity recovery rate after high-temperature storage, high capacity retention rate, low resistance increase rate, and high gas generation reduction effect.

[0011]

[0012] One embodiment provides a lithium secondary battery.

[0013] 1. A lithium secondary battery comprises: a electrode plate comprising a dried product of a slurry comprising an active material for a lithium secondary battery, a binder, and a first additive of Formula 1; and an electrolyte, wherein the electrolyte comprises a non-aqueous organic solvent; a lithium salt; and an additive, and the additive comprises one or more second additives selected from Formula 2, Formula 3, and Formula 4 below:

[0014] [Chemical Formula 1]

[0015]

[0016] (In the above chemical formula 1,

[0017] L 11 , L 12 , A and B are the same as defined in the description of the invention below).

[0018] [Chemical Formula 2]

[0019]

[0020] (In the above chemical formula 2,

[0021] L 21 , L 22 , C and D are the same as defined in the description of the invention below).

[0022] [Chemical Formula 3]

[0023]

[0024] (In the above chemical formula 3,

[0025] R 21 , R 22 and R 23 (is the same as defined in the description of the invention below).

[0026] [Chemical Formula 4]

[0027]

[0028] (In the above chemical formula 4,

[0029] R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , X and n are the same as defined in the description of the invention below).

[0030] In 2.1, the first additive is a lithium secondary battery represented by the following chemical formula 1-3:

[0031] [Chemical Formula 1-3]

[0032]

[0033] In the above chemical formula 1-3,

[0034] L 11 , L 12 , L 3A , L 3B , L 4A and L 4B Each is independently identical to as defined in the description of the invention below).

[0035] 3. A lithium secondary battery according to 1 to 2, wherein the first additive comprises one or more of the following chemical formulas 1-4 and 1-5:

[0036] [Chemical Formula 1-4]

[0037]

[0038] [Chemical Formula 1-5]

[0039]

[0040] 4. A lithium secondary battery according to 1 to 3, wherein the first additive is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the active material for the lithium secondary battery.

[0041] 5. A lithium secondary battery according to 1 to 4, wherein the active material for the lithium secondary battery comprises a lithium nickel-based oxide.

[0042] 6. A lithium secondary battery according to 1 to 5, wherein the second additive is included in an amount of 0.05 to 5 weight% relative to the total amount of the electrolyte.

[0043] 7. A lithium secondary battery in which, in 1 to 6, the second additive comprises a compound of Formula 2.

[0044] 8. A lithium secondary battery according to 1 to 7, wherein C and D are each independently of the following chemical formula 2-2, 2-3 or 2-4:

[0045] [Chemical Formula 2-2]

[0046]

[0047] [Chemical Formula 2-3]

[0048]

[0049] [Chemical Formula 2-4]

[0050]

[0051] (In the above chemical formulas 2-2, 2-3, and 2-4,

[0052] R a , R b , and R c Each is identical to as defined in the description of the invention below).

[0053] 9. A lithium secondary battery according to 1 to 8, wherein the second additive comprises one or more of the following chemical formulas 2-5 to 2-8:

[0054] [Chemical Formula 2-5]

[0055]

[0056] [Chemical Formula 2-6]

[0057]

[0058] [Chemical Formula 2-7]

[0059]

[0060] [Chemical Formula 2-8]

[0061] .

[0062] 10. A lithium secondary battery according to 1 to 11, wherein the non-aqueous organic solvent is a mixture comprising ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 40: 30 to 80.

[0063] 11. A lithium secondary battery in which, in 1 to 10, the second additive comprises a compound of the chemical formula 3.

[0064] 12. In 1 to 11, the above R 21 , R 22 lithium secondary battery, at least one of which is oxygen:

[0065] 13. A lithium secondary battery according to 1 to 12, wherein the second additive comprises one or more of the following chemical formulas 3-1 to 3-7:

[0066] [Chemical Formula 3-1]

[0067]

[0068] [Chemical Formula 3-2]

[0069]

[0070] [Chemical Formula 3-3]

[0071]

[0072] [Chemical Formula 3-4]

[0073]

[0074] [Chemical Formula 3-5]

[0075]

[0076] [Chemical Formula 3-6]

[0077]

[0078] [Chemical Formula 3-7]

[0079] .

[0080] 14. A lithium secondary battery according to 1 to 13, wherein the non-aqueous organic solvent is a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 30: 40 to 80.

[0081] 15. A lithium secondary battery in which, in 1 to 14, the second additive comprises a compound of the chemical formula 3.

[0082] 16. A lithium secondary battery according to 1 to 15, wherein the second additive comprises one or more of the following chemical formulas 4-2 and 4-3.

[0083] [Chemical Formula 4-2]

[0084]

[0085] [Chemical Formula 4-3]

[0086]

[0087] (In the above chemical formulas 4-2 and 4-3,

[0088] R 11 to R 16 Each is identical to what is defined in Chemical Formula 4 above).

[0089] 17. A lithium secondary battery according to 1 to 16, wherein the second additive comprises one or more of the following chemical formulas 4-4 to 4-8:

[0090] [Chemical Formula 4-4]

[0091]

[0092] [Chemical Formula 4-5]

[0093]

[0094] [Chemical Formula 4-6]

[0095]

[0096] [Chemical Formula 4-7]

[0097]

[0098] [Chemical Formula 4-8]

[0099] .

[0100] 18. A lithium secondary battery according to 1 to 17, wherein the non-aqueous organic solvent is a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 20: 60 to 80.

[0101] 19. A lithium secondary battery according to 1 to 18, wherein the concentration of the lithium salt is 0.1M to 3.0M and the lithium salt is LiPF6.

[0102] 20. A lithium secondary battery according to 1 to 19, wherein the electrode plate is a positive electrode, and the lithium secondary battery further comprises a negative electrode, and the negative electrode comprises a graphite and Si composite as a negative electrode active material.

[0103] 21. A lithium secondary battery according to 1 to 20, wherein the Si composite : graphite is included in a weight ratio of 3 : 97 to 20 : 80.

[0104] 22. In 1 to 21, the lithium secondary battery is a circular lithium secondary battery.

[0105] 23. In 1 to 22, the lithium secondary battery is a lithium secondary battery having a driving voltage of 4.2V or higher.

[0106]

[0107] A lithium secondary battery according to one embodiment includes a electrode plate containing a first additive of Formula 1, and after high-temperature storage, provides a high capacity recovery rate, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect.

[0108] A lithium secondary battery according to one embodiment includes a electrode plate containing a first additive of Formula 1, and provides low initial resistance, high capacity recovery rate after high-temperature storage, high capacity retention rate, low resistance increase rate, and high gas generation reduction effect.

[0109]

[0110] FIG. 1 is a conceptual diagram briefly illustrating a lithium secondary battery according to one embodiment of the present invention.

[0111] FIGS. 2 to 5 are cross-sectional views schematically illustrating a lithium secondary battery according to one embodiment.

[0112]

[0113] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0114] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0115] Unless otherwise specified in this specification, the singular form may also include the plural. Additionally, unless otherwise specified, "A or B" may mean "comprising A, comprising B, or comprising A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components to the mentioned components.

[0116] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0117] In this specification, "substitution" means that, unless otherwise defined, at least one hydrogen of a substituent or compound is substituted with a deuterium, a halogen group, a hydroxyl group, an amino group, a C1 to C30 amine group, a nitro group, a C1 to C40 silyl group, a C1 to C30 alkyl group, a C1 to C10 alkylsilyl group, a C6 to C30 arylsilyl group, a C3 to C30 cycloalkyl group, a C3 to C30 heterocycloalkyl group, a C6 to C30 aryl group, a C2 to C30 heteroaryl group, a C1 to C20 alkoxy group, a C1 to C10 fluoroalkyl group, a cyano group, or a combination thereof.

[0118] Specifically, "substitution" may mean that at least one hydrogen in the substituent or compound is substituted with deuterium, a halogen group, a C1 to C30 alkyl group, a C1 to C10 alkylsilyl group, a C6 to C30 arylsilyl group, a C3 to C30 cycloalkyl group, a C3 to C30 heterocycloalkyl group, a C6 to C30 aryl group, a C2 to C30 heteroaryl group, a C1 to C10 fluoroalkyl group, or a cyano group. For example, "substitution" may mean that at least one hydrogen in the substituent or compound is substituted with deuterium, a halogen group, a C1 to C20 alkyl group, a C6 to C30 aryl group, a C1 to C10 fluoroalkyl group, or a cyano group. Alternatively, "substitution" may mean that at least one hydrogen in the substituent or compound is substituted with a deuterium, a halogen group, a C1 to C5 alkyl group, a C6 to C18 aryl group, a C1 to C5 fluoroalkyl group, or a cyano group. For example, "substitution" may mean that at least one hydrogen in the substituent or compound is substituted with a deuterium, a cyano group, a halogen group, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a biphenyl group, a terphenyl group, a trifluoromethyl group, or a naphthyl group.

[0119] Unless otherwise defined in this specification, "*" means a part connected to the same or different atoms or chemical formulas.

[0120] Unless otherwise specifically mentioned in the chemical formulas described in this specification, hydrogen may be considered to be bonded in the structure of the chemical formula.

[0121] FIG. 1 is a conceptual diagram briefly illustrating a lithium secondary battery according to embodiments of the present invention. Referring to FIG. 1, the lithium secondary battery may include a positive electrode (10), a negative electrode (20), a separator (30), and an electrolyte (ELL).

[0122] The positive electrode (10) and the negative electrode (20) may be spaced apart from each other with a separator (30) in between. The separator (30) may be placed between the positive electrode (10) and the negative electrode (20). The positive electrode (10), the negative electrode (20), and the separator (30) may come into contact with an electrolyte (ELL). The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated within the electrolyte (ELL).

[0123] The electrolyte (ELL) may be a medium for transferring lithium ions between the positive electrode (10) and the negative electrode (20). Within the electrolyte (ELL), the lithium ions may pass through a separator (30) and move toward the positive electrode (10) or the negative electrode (20).

[0124] positive electrode (10)

[0125] A positive electrode (10) for a lithium secondary battery may include a current collector (COL1) and a positive electrode active material layer (AML1) formed on the current collector (COL1). The positive electrode active material layer (AML1) may include a positive electrode active material and may further include a binder and / or a conductive material.

[0126] For example, the anode (10) may further include an additive that can serve as a sacrificial anode.

[0127] The content of the positive active material in the positive active material layer (AML1) may be 90% to 99.5% by weight with respect to 100% by weight of the positive active material layer (AML1). The content of the binder and the conductive material may each be 0.5% to 5% by weight with respect to 100% by weight of the positive active material layer (AML1).

[0128] The above binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector (COL1). Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0129] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers containing copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0130] Al can be used as the current collector (COL1), but is not limited thereto.

[0131] positive electrode active material

[0132] As the positive active material in the positive active material layer (AML1), a compound capable of reversible intercalation and deintercalation of lithium (a lithated intercalation compound) may be used. Specifically, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0133] The above composite oxide may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0134] As an example, a compound represented by any one of the following chemical formulas may 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 b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia 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); Li a FePO4(0.90≤a≤1.8).

[0135] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al, or a combination thereof.

[0136] For example, the above-mentioned positive electrode active material may be a high-nickel positive electrode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in the lithium transition metal composite oxide is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel positive electrode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0137] Negative electrode (20)

[0138] A negative electrode (20) for a lithium secondary battery comprises a current collector (COL2) and a negative electrode active material layer (AML2) located on the current collector (COL2). The negative electrode active material layer (AML2) comprises a negative electrode active material and may further comprise a binder and / or a conductive material.

[0139] For example, the negative electrode active material layer (AML2) may contain 90% to 99% by weight of negative electrode active material, 0.5% to 5% by weight of binder, and 0% to 5% by weight of conductive material.

[0140] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector (COL2). As the binder, a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof may be used.

[0141] Examples of the above-mentioned non-aqueous binders include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, or combinations thereof.

[0142] The above-mentioned water-based binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0143] When a water-based binder is used as the above-mentioned cathode binder, a cellulose-based compound capable of imparting viscosity may be further included. As this cellulose-based compound, one or more types such as carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or alkali metal salts thereof may be mixed and used. Na, K, or Li may be used as the alkali metal.

[0144] The above dry binder is a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0145] The above conductive material is used to impart conductivity to the electrode, and any electronically conductive material that does not cause chemical changes can be used in the battery being constructed. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjenblack, carbon fiber, carbon nanofiber, carbon nanotube; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0146] As the current collector (COL2), copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.

[0147] cathode active material

[0148] The negative electrode active material in the negative electrode active material layer (AML2) comprises a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0149] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0150] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

[0151] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein Q is selected from 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 may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0152] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. The amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0153] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0154] The above Si-based or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0155] Separator (30)

[0156] Depending on the type of lithium secondary battery, a separator (30) may be present between the positive electrode (10) and the negative electrode (20). As such a separator (30), polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0157] The separator (30) may include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0158] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0159] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0160] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include, but is not limited to, inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0161] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0162] Electrolyte (ELL)

[0163] The electrolyte (ELL) for lithium secondary batteries contains a non-aqueous organic solvent and a lithium salt.

[0164] The above-mentioned non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0165] The above-mentioned non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0166] The above carbonate-based solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc.

[0167] Ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, and caprolactone may be used.

[0168] As ether-based solvents, dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. may be used. Additionally, as ketone-based solvents, cyclohexanone, etc. may be used. As alcohol-based solvents, ethyl alcohol, isopropyl alcohol, etc. may be used, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane, 1,4-dioxolane; sulfolanes, etc. may be used.

[0169] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0170] In addition, when using a carbonate-based solvent, a mixture of cyclic carbonates and chain carbonates can be used, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio of 1:1 to 1:9.

[0171] The above lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions within the battery, enabling the basic operation of a lithium secondary battery and facilitating the movement of lithium ions between the anode and cathode. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1It may include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluorobis(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFOP), and lithium bis(oxalate)borate (LiBOB).

[0172] lithium secondary battery

[0173] Lithium secondary batteries can be classified into cylindrical, prismatic, pouch, coin, etc., depending on their shape. FIGS. 2 to 5 are schematic diagrams illustrating lithium secondary batteries according to one embodiment, where FIG. 2 is a cylindrical battery, FIG. 3 is a prismatic battery, and FIGS. 4 and 5 are pouch-type batteries. Referring to FIGS. 2 to 5, the lithium secondary battery (100) may include an electrode assembly (40) with a separator (30) interposed between a positive electrode (10) and a negative electrode (20), and a case (50) in which the electrode assembly (40) is housed. The positive electrode (10), the negative electrode (20), and the separator (30) may be impregnated with an electrolyte (not shown). The lithium secondary battery (100) may include a sealing member (60) that seals the case (50) as in FIG. 2. In addition, in FIG. 3, the lithium secondary battery (100) may include a positive lead tab (11) and a positive terminal (12), a negative lead tab (21) and a negative terminal (22). As shown in FIG. 4 and FIG. 5, the lithium secondary battery (100) may include electrode tabs (70), namely a positive tab (71) and a negative tab (72), which serve as electrical passages for inducing current formed in the electrode assembly (40) to the outside.

[0174] Hereinafter, a lithium secondary battery according to one embodiment of the present invention will be described in more detail.

[0175] A lithium secondary battery comprises an active material for a lithium secondary battery, a binder, and a first additive of the following chemical formula 1; and an electrolyte.

[0176] In the above lithium secondary battery, the electrode plate can be a positive or a negative electrode, for example, a positive electrode:

[0177] [Chemical Formula 1]

[0178]

[0179] (In the above chemical formula 1,

[0180] L 11 and L 12 Each is independently a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and

[0181] A and B are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and

[0182] At least one of A and B is a group represented by the following chemical formula 1-1 or the following chemical formula 1-2.

[0183] [Chemical Formula 1-1]

[0184]

[0185] [Chemical Formula 1-2]

[0186]

[0187] (In the above Chemical Formula 1-1 and Chemical Formula 1-2,

[0188] L 13 , L 14 , L 15 and L 16 Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group).

[0189] It has been confirmed that the S(=O)2 functional group of the first additive can act as a lithium scavenger in a slurry for an electrode plate containing an active material for a lithium secondary battery. Accordingly, the first additive can prevent gelation of the slurry by suppressing the denaturation of the binder in the slurry. In addition, the first additive can improve the dispersibility of the active material and the binder within the slurry. Therefore, an electrode plate formed from a slurry containing the first additive can improve the resistance of the battery by improving the dispersibility of the active material and the binder.

[0190] In one example, the above L 11 and L 12 At least one of them may be a substituted or unsubstituted C1 to C5 alkylene group. In one example, the L 11 and L 12 Each may be an independently substituted or unsubstituted C1 to C5 alkylene group. In one example, the L 11 and L 12 At least one of them may be a substituted or unsubstituted C2 to C5 alkylene group. In one example, the L 11 and L 12 Each may be an independently substituted or unsubstituted C2 to C5 alkylene group.

[0191] In one embodiment, the first additive may be represented by the following chemical formula 1-3:

[0192] [Chemical Formula 1-3]

[0193]

[0194] In the above chemical formula 1-3,

[0195] L 11 and L 12 Each is an independently substituted or unsubstituted C2 to C5 alkylene group, and

[0196] L 3A , L 3B, L 4A and L 4B Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group.

[0197] In one embodiment, the first additive may include one or more of the following chemical formulas 1-4 and 1-5.

[0198] [Chemical Formula 1-4]

[0199]

[0200] [Chemical Formula 1-5]

[0201]

[0202] The first additive may be included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the active material for the lithium secondary battery. The "content of the first additive" may refer to the content of the compound of the first additive in the electrode plate or the slurry relative to the total weight of the active material for the lithium secondary battery in the electrode plate or the slurry, which is 100 parts by weight. Within this range, there may be effects such as inhibiting gelation of the slurry and improving battery resistance without affecting the active material and the binder. For example, the first additive may be included in an amount of 0.01 to 5 parts by weight, 0.01 to 1 part by weight, or 0.05 to 0.1 parts by weight per 100 parts by weight of the active material for the lithium secondary battery. Within this range, significant improvement in battery performance may be achieved when combined with the second additive described below.

[0203] The above-mentioned first additive can be synthesized by referring to methods known to those skilled in the art.

[0204] When the above electrode plate is a positive electrode, the active material for the lithium secondary battery can be the positive electrode active material described above.

[0205] The above-mentioned positive electrode active material may be a lithium transition metal composite oxide, and specific examples include a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free lithium nickel-manganese-based oxide, or a combination thereof.

[0206] The above positive active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 5, a lithium cobalt-based oxide represented by the following chemical formula 6, a lithium iron phosphate-based compound represented by the following chemical formula 7, a cobalt-free lithium nickel-manganese-based oxide represented by the chemical formula 8, or a combination thereof.

[0207] In one embodiment, the positive electrode active material may be a lithium nickel-based oxide represented by the chemical formula 5 below. A battery comprising a positive electrode containing the lithium nickel-based oxide as the positive electrode active material and the first additive together with the electrolyte below may have a significant effect of providing a low gas generation rate, a low resistance increase rate, and a high capacity retention rate after high-temperature storage.

[0208] [Chemical Formula 5]

[0209] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0210] In the above chemical formula 5, 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, and M 1 and M 2Each is independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S. In the above formula 5, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.88≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0211] [Chemical Formula 6]

[0212] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0213] In the above chemical formula 6, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is one or more elements selected from the group consisting 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 one or more elements selected from the group consisting of F, P, and S.

[0214] [Chemical Formula 7]

[0215] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0216] In the above chemical formula 7, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4is one or more elements selected from the group consisting 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 one or more elements selected from the group consisting of F, P, and S.

[0217] [Chemical Formula 8]

[0218] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0219] In the above chemical formula 8, 0.9≤a4≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0220] For example, the above-mentioned cathode active material may be a high-nickel cathode active material in which the nickel content relative to 100 mol% of the metal excluding lithium in the lithium transition metal composite oxide is 80 mol% or more, 88 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less. The high-nickel cathode active material can achieve high capacity and can be applied to high-capacity, high-density lithium secondary batteries.

[0221] For example, the above positive active material can be a lithium nickel-based oxide, for example, a lithium nickel cobalt aluminum-based oxide.

[0222] When the above electrode plate is a negative electrode, the active material for the lithium secondary battery may be the negative electrode active material described above. For example, the negative electrode active material may be a mixture of graphite and a Si composite.

[0223] In a specific embodiment, the negative electrode active material may include at least one of graphite and Si composites.

[0224] When the above-mentioned cathode active material includes a Si composite and graphite together, the Si composite and graphite may be included in the form of a mixture, in which case the Si composite:graphite may be included in a weight ratio of 1:99 to 50:50 based on a total of 100 parts by weight. More specifically, the Si composite:graphite may be included in a weight ratio of 3:97 to 20:80, 4:96 to 20:80, or 5:95 to 20:80.

[0225] The above Si composite comprises a core containing Si-based particles and an amorphous carbon coating layer, for example, the Si-based particles are a Si-C composite, SiO x It may include one or more of (0 < x ≤ 2) and Si alloys. For example, the Si-C composite may include a core containing Si particles and crystalline carbon and an amorphous carbon coating layer located on the surface of the core. The crystalline carbon may include, for example, graphite, and more specifically, natural graphite, artificial graphite, or a mixture thereof.

[0226] In one embodiment, when the positive electrode comprises a lithium nickel-based oxide and a first additive, the effect of improving the high-temperature stability of the lithium secondary battery can be maximized. The operating driving voltage of the lithium secondary battery of the above combination is 4.2 V or higher, and it may operate even at high voltage.

[0227] When the above electrode plate is an anode, the binder may be the binder described in the anode above. For example, the binder may be a polyvinylidene fluoride-based binder.

[0228] When the above electrode plate is the negative electrode, the binder may be the binder described in the above positive electrode. For example, the binder may be a styrene butadiene rubber-based binder.

[0229] The above slurry may further include a conductive material. It has been confirmed that the first additive can further provide an effect of reducing the aggregation of the conductive material within the slurry. Accordingly, an electrode plate formed from a slurry containing the first additive can further improve the resistance improvement effect of the battery by reducing the aggregation of the conductive material.

[0230] When the above electrode plate is an anode, the conductive material may be the conductive material described in the anode above. For example, the conductive material may be one or more of graphite, including artificial graphite, and carbon black.

[0231] When the above electrode plate is a cathode, the conductive material may be the conductive material described in the above-described cathode. For example, the conductive material may be a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, carbon nanotube; a metal-based material in the form of metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.; a conductive polymer such as a polyphenylene derivative; or a mixture thereof, but is not limited thereto.

[0232] The above electrolyte comprises a non-aqueous organic solvent; a lithium salt; and an additive, wherein the additive comprises one or more second additives selected from the following Chemical Formula 2, the following Chemical Formula 3, and the following Chemical Formula 4.

[0233] In one embodiment, the electrolyte according to the first embodiment comprises one or more compounds represented by the following chemical formula 2 as the second additive.

[0234] In another embodiment, the electrolyte according to the second embodiment comprises one or more compounds represented by the following chemical formula 3 as the second additive.

[0235] In another embodiment, the electrolyte according to the second embodiment comprises one or more compounds represented by the following chemical formula 4 as the second additive.

[0236] Electrolyte according to the first embodiment:

[0237] The above electrolyte includes one or more compounds represented by the following chemical formula 2 as the second additive.

[0238] The compound represented by Chemical Formula 2 forms a robust SEI layer at high temperatures in a battery comprising a electrode plate formed from a slurry containing the first additive of Chemical Formula 1, thereby suppressing deterioration caused by side reactions of the electrolyte and film breakdown at high temperatures, and by stabilizing LiPF6 in the lithium salt, it can suppress the generation of HF caused by the decomposition of LiPF6. In addition, it has been confirmed that the compound represented by Chemical Formula 2 can suppress the leaching of active material from the electrode plate and the deterioration of the film formed on the electrode plate in the battery, and reduce gas generation. This is thought to be due to the structure of the compound represented by Chemical Formula 2 having a sulfonate group and a triazole or imidazole group, but the present invention is not limited thereto.

[0239] In one embodiment, the second additive, for example, a compound represented by Formula 2, may be included in an amount of 0.05 to 5 weight% relative to the total amount of the electrolyte. Within this range, the effect of the electrolyte described above can be realized. Specifically, the second additive may be included in an amount of 0.1 to 5 weight%, 0.1 to 2 weight%, 0.1 to 1 weight%, or 0.5 to 1 weight% relative to the total amount of the electrolyte. When the content of the first additive is within the above range, the effect of the electrolyte described above is significantly enhanced, and there may be an additional effect of not increasing the resistance of the battery.

[0240] [Chemical Formula 2]

[0241]

[0242] (In the above chemical formula 2,

[0243] L 21 and L 22 Each is independently a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and

[0244] C and D are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and

[0245] At least one of C and D is the following chemical formula 2-1.

[0246] [Chemical Formula 2-1]

[0247]

[0248] (In the above chemical formula 2-1,

[0249] X 21 , X 22 , X 23 and X 24Each is independently a nitrogen atom (N) or CR, and

[0250] X 21 , X 22 , X 23 and X 24 One or two of them are nitrogen atoms, and

[0251] R is each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group).

[0252] In one example, C and D may each independently be the following chemical formulas 2-2, 2-3, or 2-4:

[0253] [Chemical Formula 2-2]

[0254]

[0255] [Chemical Formula 2-3]

[0256]

[0257] [Chemical Formula 2-4]

[0258]

[0259] (In the above chemical formulas 2-2, 2-3, and 2-4,

[0260] R a , R b , and R c Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group).

[0261] In one example, the second additive may include one or more of the following chemical formulas 2-5 to 2-8:

[0262] [Chemical Formula 2-5]

[0263]

[0264] [Chemical Formula 2-6]

[0265]

[0266] [Chemical Formula 2-7]

[0267]

[0268] [Chemical Formula 2-8]

[0269]

[0270] For example, the second additive may include one or more of the chemical formulas 2-5 and 2-7.

[0271] The above second additive can be synthesized by referring to methods known to those skilled in the art.

[0272] A non-aqueous organic solvent according to one embodiment of the present invention may include one or more of the non-aqueous organic solvents described above.

[0273] In one embodiment, the non-aqueous organic solvent may be a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 50: 30 to 80. Here, the volume ratio is a value based on 100 volume% of the total of ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC). Within the above range, the effect of the second additive is easily realized, and the rate of reductive decomposition of the anode in the lithium secondary battery is slowed down, thereby further improving the battery life.

[0274] The above lithium salt may include one or more selected from the group consisting of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiSO3CF3, LiBOB, LiFOB, LiDFBP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, and LiC4F9SO3. According to one embodiment, LiPF6 may be used as the lithium salt.

[0275] The concentration of the lithium salt may be 0.1M to 3.0M. Specifically, the concentration of the lithium salt may be 0.5M or higher and 1.0M or higher. The concentration of the lithium salt may be 3.0M or lower, 2.5M or lower, and 2.0M or lower. In the present invention, when the concentration of the lithium salt is 0.1M to 2.0M, the conductivity and viscosity of the electrolyte can be appropriately maintained.

[0276] Electrolyte according to the second embodiment:

[0277] The above electrolyte includes one or more compounds represented by the following chemical formula 3 as the second additive.

[0278] The compound represented by Chemical Formula 3 forms a robust SEI layer at high temperatures in a battery comprising a electrode plate formed from a slurry containing the first additive of Chemical Formula 1, thereby suppressing deterioration caused by side reactions of the electrolyte and film breakdown at high temperatures, and by stabilizing LiPF6 in the lithium salt, it can suppress the generation of HF caused by the decomposition of LiPF6. In addition, it has been confirmed that the compound represented by Chemical Formula 3 can suppress the leaching of active material from the electrode plate and the deterioration of the film formed on the electrode plate in the battery, and reduce gas generation. This is thought to be due to the compound represented by Chemical Formula 3 having a cyclic structure and a sulfonate group simultaneously, but the present invention is not limited thereto.

[0279] The second additive, for example, a compound represented by Formula 3, may be included in an amount of 0.05 to 5 weight% relative to the total amount of the electrolyte. Within this range, the effect of the electrolyte described above can be realized. Specifically, the second additive may be included in an amount of 0.1 to 5 weight%, 0.1 to 2 weight%, 0.1 to 2 weight%, or 0.5 to 1 weight% relative to the total amount of the electrolyte. When the content of the second additive is within the above range, the effect of the electrolyte described above is significantly enhanced, and there may be an additional effect of not increasing the resistance of the battery.

[0280] [Chemical Formula 3]

[0281]

[0282] (In the above chemical formula 3,

[0283] R 21 and R 22 Each independently uses oxygen or CR 1 R 2 and, the above R 1 and R 2Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group, and

[0284] R 23 is a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C1 to C5 alkyleneoxy group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group).

[0285] Here, 'C1 to C5 alkyleneoxy group' may refer to an alkylene group having oxygen within the main chain and having a total of 1 to 5 carbons in the main chain.

[0286] R 21 , R 22 At least one of them may be oxygen. In this case, the effect in a battery comprising an electrode plate formed from a slurry containing the first additive may be significant.

[0287] R 21 , R 22 One of them may be oxygen. In this case, the effect may be more pronounced in a battery comprising an electrode plate formed from a slurry containing the first additive.

[0288] R 21 , R 22 CR each independently 1 R 2 It could be.

[0289] R 23 It may be a substituted or unsubstituted C1 to C5 alkylene group or a substituted or unsubstituted C1 to C5 alkyleneoxy group. In this case, the effect may be significant in a battery comprising an electrode plate formed from a slurry containing the first additive.

[0290] R 23It may be a substituted or unsubstituted C1 to C2 alkylene group or a substituted or unsubstituted C1 to C2 alkylene oxy group. In this case, the effect may be more pronounced in a battery comprising an electrode plate formed from a slurry containing the first additive.

[0291] The second additive above may include one or more of the following chemical formulas 3-1 to 3-7:

[0292] [Chemical Formula 3-1]

[0293]

[0294] [Chemical Formula 3-2]

[0295]

[0296] [Chemical Formula 3-3]

[0297]

[0298] [Chemical Formula 3-4]

[0299]

[0300] [Chemical Formula 3-5]

[0301]

[0302] [Chemical Formula 3-6]

[0303]

[0304] [Chemical Formula 3-7]

[0305]

[0306] For example, the second additive may include one or more of the chemical formulas 3-1 and 3-2.

[0307] The above-mentioned non-aqueous organic solvent may include one or more of the non-aqueous organic solvents described above.

[0308] The above-mentioned non-aqueous organic solvent may be a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 30: 40 to 80. Here, the volume ratio is a value based on 100 volume% of the total of ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC). Within the above range, the effect of the second additive is easily realized, and the rate of reductive decomposition of the anode in the lithium secondary battery is slowed down, thereby further improving the battery life.

[0309] The above lithium salt may include one or more selected from the group consisting of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiSO3CF3, LiBOB, LiFOB, LiDFBP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, and LiC4F9SO3. According to one embodiment, LiPF6 may be used as the lithium salt.

[0310] The concentration of the lithium salt may be 0.1M to 3.0M. Specifically, the concentration of the lithium salt may be 0.5M or higher and 1.0M or higher. The concentration of the lithium salt may be 3.0M or lower, 2.5M or lower, and 2.0M or lower. In the present invention, when the concentration of the lithium salt is 0.1M to 2.0M, the conductivity and viscosity of the electrolyte can be appropriately maintained.

[0311] Electrolyte according to the third embodiment:

[0312] The above electrolyte includes one or more compounds represented by the following chemical formula 4 as the second additive.

[0313] The compound represented by Chemical Formula 4 forms a high-temperature robust SEI layer on an electrode plate in a battery comprising an electrode plate formed from a slurry containing the first additive of Chemical Formula 1, thereby suppressing degradation caused by side reactions of the electrolyte and film breakdown at high temperatures, and stabilizing LiPF6 among lithium salts, thereby LiPF6 6 The generation of HF due to the decomposition of can be suppressed. In addition, it has been confirmed that the compound represented by Chemical Formula 4 can suppress the leaching of the active material from the electrode plate and the deterioration of the film formed on the electrode plate in the battery, and reduce gas generation. This is thought to be due to the compound represented by Chemical Formula 4 having a halogen-substituted cyclic phosphite group, but the present invention is not limited thereto.

[0314] In one embodiment, the second additive, for example, a compound represented by Formula 4, may be included in an amount of 0.05 to 5 weight% relative to the total amount of the electrolyte. Within this range, the effect of the electrolyte described above can be realized. Specifically, the second additive may be included in an amount of 0.1 to 5 weight%, 0.1 to 2 weight%, 0.1 to 2 weight%, 0.1 to 1 weight%, or 0.5 to 1 weight% relative to the total amount of the electrolyte. When the content of the second additive is within the above range, the effect of the electrolyte described above is significantly enhanced, and there may be an additional effect of not increasing the resistance of the battery.

[0315] The above second additive is represented by the following chemical formula 4.

[0316] [Chemical Formula 4]

[0317]

[0318] (In the above chemical formula 4,

[0319] X is a fluoro group, chloro group, bromo group, or iodo group, and

[0320] R 11 to R 16Each is independently hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and

[0321] n is an integer of 0 or 1).

[0322] The above second additive can be represented by the following chemical formula 4-1:

[0323] [Chemical Formula 4-1]

[0324]

[0325] (In the above chemical formula 4-1,

[0326] R 11 to R 16 , n are each the same as defined in Chemical Formula 4 above).

[0327] A second additive according to another embodiment of the present invention may include one or more of the following chemical formulas 4-2 and 4-3.

[0328] [Chemical Formula 4-2]

[0329]

[0330] [Chemical Formula 4-3]

[0331]

[0332] (In the above chemical formulas 4-2 and 4-3,

[0333] R 11 to R 16 Each is identical to what is defined in Chemical Formula 4 above).

[0334] In one specific example, R 11 to R 16Each may be hydrogen or a substituted or unsubstituted C1 to C10 alkyl group, for example, hydrogen or a substituted or unsubstituted C1 to C5 alkyl group.

[0335] For example, the second additive may be one or more of the following chemical formulas 4-4 to 4-8: For example, the second additive may be one or more of the following chemical formulas 4-5, 4-6, and 4-8.

[0336] [Chemical Formula 4-4]

[0337]

[0338] [Chemical Formula 4-5]

[0339]

[0340] [Chemical Formula 4-6]

[0341]

[0342] [Chemical Formula 4-7]

[0343]

[0344] [Chemical Formula 4-8]

[0345]

[0346] The above second additive can be manufactured by conventional methods known to those skilled in the art.

[0347] A non-aqueous organic solvent according to one embodiment of the present invention may include one or more of the non-aqueous organic solvents described above.

[0348] In one embodiment, the non-aqueous organic solvent may be a mixture containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 20: 60 to 80. Here, the volume ratio is a value based on 100 volume% of the total of ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC). Within the above range, the effect of the second additive is easily realized, and the rate of reductive decomposition of the anode in the lithium secondary battery is slowed down, thereby further improving the battery life.

[0349] A lithium salt according to one embodiment of the present invention may include one or more selected from the group consisting of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiSO3CF3, LiBOB, LiFOB, LiDFBP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, and LiC4F9SO3. According to one embodiment, LiPF6 may be used as the lithium salt.

[0350] The concentration of the lithium salt may be 0.1M to 3.0M. Specifically, the concentration of the lithium salt may be 0.5M or higher and 1.0M or higher. The concentration of the lithium salt may be 3.0M or lower, 2.5M or lower, and 2.0M or lower. In the present invention, when the concentration of the lithium salt is 0.1M to 2.0M, the conductivity and viscosity of the electrolyte can be appropriately maintained.

[0351] The above electrolyte can be prepared by dissolving a lithium salt in a non-aqueous organic solvent, adding the second additive, and then performing a mixing process. The process of mixing the electrolyte is widely known in the field of electrolyte manufacturing, and a person skilled in the art would be able to appropriately select and use it.

[0352] The above lithium secondary battery may be a cylindrical or prismatic battery.

[0353]

[0354] Examples and comparative examples of the present invention are described below. However, the following examples are merely one example of the present invention, and the present invention is not limited to the following examples.

[0355] Example 1

[0356] (1) Preparation of anode slurry

[0357] LiNi as a positive electrode active material 0.91 Co 0.08 Al 0.01 O297 wt%, 0.5 wt% artificial graphite powder and 1 wt% carbon black (Ketjenblack) as conductive materials, and 1.5 wt% polyvinylidene fluoride (PVdF) as a binder were mixed, and 0.05 wt% of the compound of Formula 1-4 below was mixed as a first additive with respect to 100 wt% of the cathode active material, and after adding to N-methyl-2-pyrrolidone (NMP), the mixture was stirred for 30 minutes using a mechanical stirrer to prepare a cathode slurry. The compound of Formula 1-4 was synthesized by referring to known literature.

[0358] [Chemical Formula 1-4]

[0359]

[0360] (2) Preparation of electrolyte

[0361] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:10:70 of a total volume of 100, adding 0.5 wt% of a second additive to the electrolyte, and mixing. The second additive was represented by the following chemical formula 2-5. The compound of the following chemical formula 2-5 was synthesized by referring to known literature.

[0362] [Chemical Formula 2-5]

[0363]

[0364] (3) Manufacturing of lithium secondary batteries

[0365] The positive active material slurry prepared in (1) above was applied to a thickness of about 60 μm on a 20 μm thick aluminum foil using a doctor blade, dried for 0.5 hours in a hot air dryer at 100 ℃, dried again for 4 hours under vacuum conditions at 120 ℃, and then rolled to produce a positive electrode.

[0366] A cathode active material slurry was prepared by mixing 98 wt% of a cathode active material, in which a graphite and Si composite was mixed in a weight ratio of 95.8:4.2, 1 wt% of styrene-butadiene rubber (SBR), and 1 wt% of carboxymethylcellulose (CMC), adding the mixture to distilled water, and stirring for 60 minutes using a mechanical stirrer. The slurry was applied to a thickness of about 60 μm on a 10 μm thick copper current collector using a doctor blade, dried in a hot air dryer at 100 ℃ for 0.5 hours, dried once more under vacuum conditions at 120 ℃ for 4 hours, and then rolled to produce a cathode.

[0367] An electrode assembly was manufactured by assembling the above positive electrode and the above negative electrode with a separator made of polyethylene material with a thickness of 16 μm, and a circular lithium secondary battery (4.2V class) was manufactured by injecting the above electrolyte.

[0368] Example 2

[0369] A battery was manufactured in the same manner as in Example 1, except that the content of the second additive in Example 1 was changed as shown in Table 1 below.

[0370] Example 3

[0371] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:40:40 of a total volume of 100, adding 1.0 wt% of a second additive to the electrolyte and mixing. The second additive used was the following Chemical Formula 2-7. A battery was manufactured in the same manner as in Example 1, except that the electrolyte prepared above was used in Example 1. The compound of Chemical Formula 2-7 was synthesized by referring to known literature.

[0372] [Chemical Formula 2-7]

[0373]

[0374]

[0375] Examples 4 to 5

[0376] A battery was manufactured in the same manner as in Example 1, except that the content of the compound of Formula 1-4 as the first additive was changed with respect to 100 parts by weight of the positive active material in the positive active material slurry in Example 1, and / or the content of the compound of Formula 2-5 as the second additive in the electrolyte was changed.

[0377]

[0378] Comparative Examples 1 to 3

[0379] A battery was manufactured in the same manner as in Example 1, except that the content of the compound of Formula 1-4 as the first additive was changed with respect to 100 parts by weight of the positive active material in the positive active material slurry in Example 1, and / or the content of the compound of Formula 2-5 as the second additive in the electrolyte was changed.

[0380]

[0381] Comparative Example 4

[0382] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:40:40 of a total volume of 100, adding 1.0 wt% of a second additive to the electrolyte and mixing. The second additive was provided by the following chemical formula 9.

[0383] [Chemical Formula 9]

[0384]

[0385]

[0386] Evaluation example

[0387] The positive electrode active material slurry and the lithium secondary battery were evaluated in the following manner.

[0388] Evaluation 1: Viscosity of cathode active material slurry (Unit: mPa.s)

[0389] The viscosity of the cathode active material slurries of the examples and comparative examples was measured using the DV-2+ PRO model from BROOKFIELD. The measurement was performed at room temperature (25℃), and the measurement conditions were as follows. For 100 ml of cathode slurry, the viscosity value was checked after 20 seconds by rotating it at 20 rpm using the No. S95 spindle, which is a T-type D spindle.

[0390] Evaluation 2: Initial Resistance (Unit: mΩ)

[0391] The lithium secondary batteries of the examples and comparative examples were charged at a constant current rate of 0.5C at 25°C until the voltage reached 4.2V, and then cut off at a current rate of 0.05C while maintaining 4.2V in constant voltage mode. Subsequently, the direct current internal resistance (DC-IR) was measured by discharging at a constant current rate of 1.0C for 30 seconds.

[0392] Evaluation 3: Remaining Capacity After High-Temperature Storage (Unit: %) and Capacity Recovery Rate (Recovery, Rec) (Unit: %)

[0393] The lithium secondary batteries of the Examples and Comparative Examples were subjected to 0.5C CC / CV charging (4.2V, 0.05C CUT-OFF) and 0.5C CC discharging (2.5V CUT-OFF) at 25°C three times, and the discharge capacity C1 was measured during the third cycle. After storing the charged lithium secondary batteries at 60°C for 60 days, they were left at room temperature for an additional 4 hours, and the discharge capacity C2 was measured by 0.5C CC discharging (2.5V CUT-OFF). The capacity retention rate (remaining capacity) was calculated as follows.

[0394] Capacity retention rate (%) = C2 / C1 × 100.

[0395] After measuring the capacity retention rate of the lithium secondary batteries of the examples and comparative examples in the same manner as above, the discharge capacity was measured by charging at a 0.5C-rate CC / CV (4.2V, 0.05C cut-off) and discharging at a 0.5C-rate CC (2.5V cut-off).

[0396] The capacity recovery rate was calculated as a percentage by dividing the discharge capacity after measuring the capacity retention rate by the initial capacity measured above.

[0397] Capacity recovery rate (%) = (Discharge capacity after capacity retention rate measurement / Initial capacity) × 100.

[0398] Evaluation 4: Increase rate of DCIR (direct current internal resistance) after high-temperature storage (Unit: %)

[0399] For the lithium secondary batteries according to the examples and comparative examples, the initial DC resistance (DCIR) was measured using the △V / △I (change in voltage / change in current) value, the maximum energy state inside the battery was made to a fully charged state (SOC 100%), and after storing it at 60°C for 60 days in this state, the DC resistance was measured, and the DCIR increase rate (%) was calculated according to the following formula.

[0400] DCIR growth rate (%) = (DCIR after 60 days at 60℃ / Initial DCIR) × 100.

[0401] Evaluation 5: Gas generation amount after high-temperature storage (Unit: mL) and gas increase / decrease rate (Unit: %)

[0402] High-temperature gas generation characteristics were evaluated for lithium secondary batteries according to the examples and comparative examples. To this end, the maximum energy state inside the battery was set to a fully charged state (SOC 100%), and the amount of gas generated was evaluated in this state initially (before storage at 60°C) and after storage at 60°C for 60 days. The gas change rate was calculated by measuring the volume change before and after high-temperature storage and converting it into a mass change using Archimedes' method. The gas change rate was calculated as [(amount of gas generated in the examples and comparative examples - amount of gas generated in Comparative Example 1) / amount of gas generated in Comparative Example 1] × 100.

[0403] The results of the above evaluation are shown in Table 1 below.

[0404] Slurry Electrolyte Slurry Viscosity Initial Resistance Capacity Retention Rate Capacity Recovery Rate DC-IR Increase Rate Gas Generation Amount Gas Increase / Decrease Rate Chemical Formula 1-4 Chemical Formula 2-5 Chemical Formula 2-7 Chemical Formula 9 Comparative Example 1 0000 5720 31.1 75.18 2.3 26.0 2.060 Comparative Example 2 0.5000 275 63 3.76 9.3 75.9 25.12 238.3 Comparative Example 3 0 2.000 5720 32.2 72.5 79.5 25.5 1.98 -3.9 Comparative Example 4 0.0500 1.02 191 35.96 7.17 3.6 27.9 2.45 18.9 Example 1 0.05 0.500 219 127.98 3.79 1.7 14.71.26-38.8 Example 20.051.000219128.886.494.718.31.57-23.8 Example 30.0501.00219129.285.193.019.81.70-17.5 Example 40.10.500226128.184.392.419.21.65-19.9 Example 50.11.000226129.387.996.320.11.72-16.5

[0405]

[0406] synthesis

[0407] Referring to Table 1 above, the lithium secondary battery of the example includes a positive electrode containing a first additive of Formula 1 and an electrolyte containing a second additive of Formula 2, thereby providing a high capacity recovery rate, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect after high-temperature storage.

[0408] However, referring to Table 1 above, the lithium secondary battery of the comparative example had a weak effect compared to the example.

[0409]

[0410] Example 6

[0411] (1) Preparation of anode slurry

[0412] LiNi as a positive electrode active material 0.91 Co 0.08 Al 0.01O297 wt%, 0.5 wt% artificial graphite powder and 1 wt% carbon black (Ketjenblack) as conductive materials, and 1.5 wt% polyvinylidene fluoride (PVdF) as a binder were mixed, and 0.05 wt% of a compound of Formula 1-4 below was mixed as a first additive with respect to 100 wt% of the cathode active material, and after adding to N-methyl-2-pyrrolidone (NMP), the mixture was stirred for 30 minutes using a mechanical stirrer to prepare a cathode slurry. Formula 1-4 was synthesized by referring to known literature.

[0413] [Chemical Formula 1-4]

[0414]

[0415] (2) Preparation of electrolyte

[0416] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:10:70 of a total volume of 100, adding 0.5 wt% of a second additive to the electrolyte, and mixing. The second additive was represented by the following chemical formula 3-1. Chemical formula 3-1 was synthesized by referring to known literature.

[0417] [Chemical Formula 3-1]

[0418]

[0419] (3) Manufacturing of lithium secondary batteries

[0420] The positive active material slurry prepared in (1) above was applied to a thickness of about 60 μm on a 20 μm thick aluminum foil using a doctor blade, dried for 0.5 hours in a hot air dryer at 100 ℃, dried again for 4 hours under vacuum conditions at 120 ℃, and then rolled to produce a positive electrode.

[0421] A cathode active material slurry was prepared by mixing 98 wt% of a cathode active material, in which a graphite and Si composite was mixed in a weight ratio of 95.8:4.2, 1 wt% of styrene-butadiene rubber (SBR), and 1 wt% of carboxymethylcellulose (CMC), adding the mixture to distilled water, and stirring for 60 minutes using a mechanical stirrer. The slurry was applied to a thickness of about 60 μm on a 10 μm thick copper foil using a doctor blade, dried in a hot air dryer at 100 ℃ for 0.5 hours, dried once more under vacuum conditions at 120 ℃ for 4 hours, and then rolled to produce a cathode.

[0422] An electrode assembly was manufactured by assembling the above positive electrode and the above negative electrode with a separator made of polyethylene material with a thickness of 16 μm, and a circular lithium secondary battery (4.2V class) was manufactured by injecting the above electrolyte.

[0423]

[0424] Example 7

[0425] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:10:70 of a total volume of 100, adding 1.0 wt% of a second additive, and mixing. The second additive used was the formula 3-2 below. A battery was manufactured using the prepared electrolyte in the same manner as in Example 6. Formula 3-2 was synthesized by referring to known literature.

[0426] [Chemical Formula 3-2]

[0427]

[0428]

[0429] Examples 8 to 11

[0430] A battery was manufactured in the same manner as in Example 6, except that in Example 1, the content of the compound of Formula 1-4 as the first additive was changed with respect to 100 parts by weight of the positive active material in the positive active material slurry, and / or the content of the compound of Formula 3-1 as the second additive in the electrolyte was changed.

[0431]

[0432] Comparative Example 1, Comparative Example 4, and Comparative Example 6

[0433] A battery was manufactured in the same manner as in Example 6, except that the content of the first additive was changed with respect to 100 parts by weight of the positive active material in the positive active material slurry and / or the content of the compound of Formula 3-1 as the second additive in the electrolyte was changed.

[0434]

[0435] Comparative Example 5

[0436] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:10:70 of a total volume of 100, adding 1.0 wt% of a second additive, and mixing. The second additive used was the following chemical formula 10 (CAS 109-03-5).

[0437] [Chemical Formula 10]

[0438]

[0439]

[0440] Evaluation example

[0441] The positive electrode active material slurry and the lithium secondary battery were evaluated in the following manner.

[0442] Evaluation 1: Viscosity of cathode active material slurry (Unit: mPa.s)

[0443] The viscosity of the cathode active material slurries of the examples and comparative examples was measured using the DV-2+ PRO model from BROOKFIELD. The measurement was performed at room temperature (25℃), and the measurement conditions were as follows. For 100 ml of cathode slurry, the viscosity value was checked after 20 seconds by rotating it at 20 rpm using the No. S95 spindle, which is a T-type D spindle.

[0444] Evaluation 2: Remaining Capacity After High-Temperature Storage (Unit: %) and Capacity Recovery Rate (Recovery, Rec) (Unit: %)

[0445] The lithium secondary batteries of the Examples and Comparative Examples were subjected to 0.33C CC / CV charging (4.2V, 0.02C CUT-OFF) and 0.33C CC discharging (2.5V CUT-OFF) at 25°C three times, and the discharge capacity C1 was measured during the third cycle. After storing the charged lithium secondary batteries at 55°C for 60 days, they were left at room temperature for an additional 4 hours, and the discharge capacity C2 was measured by 0.33C CC discharging (2.5V CUT-OFF). The capacity retention rate was calculated as follows.

[0446] Capacity retention rate (%) = C2 / C1 × 100(%)

[0447] After measuring the capacity retention rate of the lithium secondary batteries of the examples and comparative examples in the same manner as above, the discharge capacity was measured by charging at a 0.33C-rate CC / CV (4.2V, 0.05C cut-off) and discharging at a 0.33C-rate CC (2.5V cut-off).

[0448] The capacity recovery rate was calculated as a percentage by dividing the discharge capacity after measuring the capacity retention rate by the initial capacity measured above.

[0449] Capacity Recovery Rate (%) = (Discharge Capacity after Capacity Retention Rate Measurement / Initial Capacity) × 100

[0450] Evaluation 3: High-Temperature Storage Characteristics Evaluation DCIR Growth Rate (Unit: %)

[0451] For the lithium secondary batteries according to the examples and comparative examples, the initial DC resistance (DCIR) was measured using the △V / △I (change in voltage / change in current) value, the maximum energy state inside the battery was made to a fully charged state (SOC 100%), and after storing it at 55°C for 60 days in this state, the DC resistance was measured, and the DCIR increase rate (%) was calculated according to the following formula.

[0452] DCIR growth rate (%) = (DCIR after 60 days / Initial DCIR) * 100.

[0453] Evaluation 4: High-temperature storage characteristics Gas generation amount (unit: mL) and gas increase / decrease rate (unit: %)

[0454] High-temperature gas generation characteristics were evaluated for lithium secondary batteries according to the examples and comparative examples. To this end, the maximum energy state inside the battery was set to a fully charged state (SOC 100%), and in this state, the amount of gas generated (unit: mL) was evaluated at an initial high temperature (before storage at 55°C) and after storage at 55°C for 60 days. The ratio of gas generation was calculated by measuring the volume change before and after high-temperature storage and converting it into a change in mass using Archimedes' method. The gas increase / decrease rate was calculated as (amount of gas generated in the examples and comparative examples - amount of gas generated in Comparative Example 1) / amount of gas generated in Comparative Example 1 x 100.

[0455] The results of the above evaluation are shown in Table 2 below.

[0456] Slurry Electrolyte Slurry Viscosity Capacity Retention Rate Capacity Recovery Rate DC-IR Increase Rate Gas Generation Amount Gas Increase / Decrease Rate Chemical Formula 1-4 Chemical Formula 3-1 Chemical Formula 3-2 Chemical Formula 10 Comparative Example 10000572074.281.321.51.850 Comparative Example 40.5000275668.775.323.32.008.1 Comparative Example 50.05001.0219165.872.425.11.927.2 Comparative Example 602.000572071.978.821.41.83-1.1 Example 60.050.500219183.791.714.71.26-31.9 Example 70.0501.00219182.493.420.11.42-23.2 Example 80.051.000219186.795.018.31.57-15.1 Example 90.10.500226184.993.019.41.66-10.3 Example 100.11.000226188.296.720.21.73-6.5 Example 110.12.000226189.798.420.51.76-4.9

[0457]

[0458] Referring to Table 2 above, the lithium secondary battery of the example includes a electrode plate containing the first additive of Formula 1, and after high-temperature storage, provided a high capacity recovery rate, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect.

[0459] However, referring to Table 2 above, the battery of the comparative example, which did not satisfy the battery configuration of the example, had a weak effect compared to the example.

[0460]

[0461] Example 12

[0462] (1) Preparation of anode slurry

[0463] LiNi as a positive electrode active material 0.94 Co 0.05 Al 0.01A positive electrode active material slurry was prepared by mixing 298.45 wt% of O, 0.35 wt% of carbon nanotubes as a conductive material, and 1.2 wt% of polyvinylidene fluoride (PVdF) with N-methyl-2-pyrrolidone (NMP). A positive electrode slurry was prepared by mixing 0.05 wt% of a compound of Formula 1-4 below as a first additive with 100 wt% of the positive electrode active material and stirring. Formula 1-4 was synthesized by referring to known literature.

[0464] [Chemical Formula 1-4]

[0465]

[0466] (2) Preparation of electrolyte

[0467] An electrolyte was prepared by dissolving 1.5 M LiPF6 in a non-aqueous organic solvent in which ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate were mixed in a volume ratio of 20:10:70 of a total volume of 100, adding 0.5 wt% of a second additive to the electrolyte, and mixing. The second additive was represented by the following chemical formula 4-5. Chemical formula 4-5 was synthesized by referring to known literature.

[0468] [Chemical Formula 4-5]

[0469]

[0470] (3) Manufacturing of lithium secondary batteries

[0471] The anode slurry prepared in (1) above was applied to a thickness of about 60 μm on a 20 μm thick aluminum foil using a doctor blade, dried for 0.5 hours in a hot air dryer at 100 ℃, dried once more in a vacuum at 120 ℃ for 4 hours, and then rolled to produce an anode.

[0472] A cathode slurry was prepared by mixing 98 wt% of a cathode active material, in which a graphite and Si composite was mixed in a weight ratio of 95.8:4.2, 1 wt% of styrene-butadiene rubber (SBR), and 1 wt% of carboxymethylcellulose (CMC), adding the mixture to distilled water, and stirring for 60 minutes using a mechanical stirrer. The slurry was applied to a thickness of about 60 μm onto a 10 μm thick copper current collector using a doctor blade, dried in a hot air dryer at 100 ℃ for 0.5 hours, dried once more under vacuum conditions at 120 ℃ for 4 hours, and then rolled to produce a cathode.

[0473] An electrode assembly was manufactured by assembling the above positive electrode and the above negative electrode with a separator made of polyethylene material with a thickness of 16 μm, and a circular lithium secondary battery (4.2V class) was manufactured by injecting the above electrolyte.

[0474]

[0475] Example 13

[0476] A battery was manufactured in the same manner as in Example 12, except that 1% by weight of the compound of Formula 4-5, which is the second additive, was used when preparing the electrolyte in Example 1.

[0477]

[0478] Example 14

[0479] A battery was manufactured in the same manner as in Example 12, except that 0.1 parts by weight of the compound of Formula 1-4, which is the first additive, was used for 100 parts by weight of the positive electrode active material when preparing the positive electrode slurry in Example 1.

[0480]

[0481] Example 15

[0482] A battery was manufactured in the same manner as in Example 12, except that in Example 12, 0.1 parts by weight of the compound of Formula 1-4, which is the first additive, was used for 100 parts by weight of the anode active material when preparing the anode slurry, and 1% by weight of the compound of Formula 4-5, which is the second additive, was used when preparing the electrolyte.

[0483]

[0484] Comparative Examples 7 to 8

[0485] A battery was manufactured in the same manner as in Example 12, except that the usage amounts of the compound of Formula 1-4, which is the first additive, and the compound of Formula 4-5, which is the second additive, were changed as shown in Table 3 below when preparing the anode slurry and electrolyte in Example 12.

[0486]

[0487] Comparative Example 9

[0488] A battery was manufactured in the same manner as in Example 12, except that the compound of Formula 4-5, which is the second additive in Example 12, was not used, and the compound of Formula 11 below was used in the electrolyte at 1% by weight. Formula 11 was synthesized by referring to known literature.

[0489] [Chemical Formula 11]

[0490]

[0491]

[0492] Evaluation example

[0493] The positive electrode active material slurry and the lithium secondary battery were evaluated in the following manner.

[0494] Evaluation 1: Viscosity of cathode active material slurry (Unit: mPa.s)

[0495] The viscosity of the cathode active material slurries of the examples and comparative examples was measured using the DV-2+ PRO model from BROOKFIELD. The measurement was performed at room temperature (25℃), and the measurement conditions were as follows: 100 ml of cathode slurry was rotated at 20 rpm using the No. S95 spindle, a T-type D spindle, and the viscosity value was checked after 20 seconds.

[0496] Evaluation 2: Initial Resistance (Unit: mΩ)

[0497] The lithium secondary batteries of the examples and comparative examples were charged at a constant current rate of 0.5C at 25°C until the voltage reached 4.2V, and then cut off at a current rate of 0.05C while maintaining 4.2V in constant voltage mode. Subsequently, the direct current internal resistance (DC-IR) was measured by discharging at a constant current rate of 1.0C for 30 seconds.

[0498] Evaluation 3: Remaining capacity after high-temperature storage (Unit: %) and capacity recovery rate (Unit: %)

[0499] The lithium secondary batteries of the Examples and Comparative Examples were subjected to 0.33C CC / CV charging (4.2V, 0.025C CUT-OFF) and 0.2C CC discharging (2.5V CUT-OFF) at 25°C twice, and the second discharge capacity C1 was measured. After storing the charged lithium secondary batteries at 60°C for 60 days, they were left at room temperature for an additional 30 minutes, and the discharge capacity C2 was measured by 0.2C CC discharging (2.5V CUT-OFF). The capacity retention rate (remaining capacity) was calculated as follows.

[0500] Capacity retention rate (%) = C2 / C1 × 100.

[0501] After measuring the capacity retention rate of the lithium secondary batteries of the examples and comparative examples in the same manner as above, the discharge capacity was measured by charging at a 0.33 C-rate CC / CV (4.2 V, 0.025 C cut-off) and discharging at a 0.2 C-rate CC (2.5 V cut-off).

[0502] The capacity recovery rate was calculated as a percentage by dividing the discharge capacity after measuring the capacity retention rate by the initial capacity measured above.

[0503] Capacity recovery rate (%) = (Discharge capacity after capacity retention rate measurement / Initial capacity) × 100.

[0504] Evaluation 4: Increase in DCIR after high-temperature storage (Unit: %)

[0505] For the lithium secondary batteries according to the examples and comparative examples, the initial DC resistance (DCIR) was measured using the △V / △I (change in voltage / change in current) value, the maximum energy state inside the battery was made to a fully charged state (SOC 100%), and after storing it at 60°C for 60 days in this state, the DC resistance was measured, and the DCIR increase rate (%) was calculated according to the following formula.

[0506] DCIR growth rate (%) = (DCIR after 60 days / Initial DCIR) × 100.

[0507] Evaluation 5: Gas generation amount after high-temperature storage (Unit: mL) and gas increase / decrease rate (Unit: %)

[0508] High-temperature gas generation characteristics were evaluated for lithium secondary batteries according to the examples and comparative examples. To this end, the maximum energy state inside the battery was set to a fully charged state (SOC 100%), and the amount of gas generated (unit: mL) was evaluated after initial storage (before storage at 60°C) and storage at 60°C for 60 days. The amount of gas generated was calculated by measuring the volume change before and after high-temperature storage and converting it into a change in mass using Archimedes' method. The gas increase / decrease rate was calculated as [(amount of gas generated in the examples and comparative examples - amount of gas generated in Comparative Example 1) / amount of gas generated in Comparative Example 1] × 100.

[0509] Evaluation 6: DSC (differential scanning calorimetry) calorific value (unit: kJ / g)

[0510] For the lithium secondary batteries of the examples and comparative examples, the batteries were disassembled to a fully charged state of 4.2V, the positive electrodes were recovered, washed with dimethylene chloride (DMC), and dried. The positive electrodes and electrolytes were placed in a pressure-resistant pan for DSC measurement, and the temperature range was measured from 40℃ to 400℃ with a heating rate of 10℃ / min.

[0511]

[0512] Slurry Electrolyte Viscosity Initial Resistance Residual Capacity Capacity Recovery Rate DCIR Increase Rate Gas Generation Amount Gas Increase / Decrease Rate DSC Calorific Value Chemical Formula 1-4 Chemical Formula 4-5 Chemical Formula 11 Comparative Example 7000572032.175.983.121.71.8303.56 Comparative Example 8030572133.273.181.421.51.81-1.13.17 Comparative Example 90.0501221334.271.478.225.71.903.83.24 Example 120.050.50221327.285.193.318.51.33-27.32.97 Example 130.0510221328.488.897.316.21.27-30.62.82 Example 140.10.50228427.984.592.620.31.70-7.12.85 Example 150.110228429.187.395.619.41.65-9.82.71

[0513]

[0514] synthesis

[0515] Referring to Table 3 above, the lithium secondary battery of the example includes a electrode plate containing the first additive of Formula 1, and provided low initial resistance, a high capacity recovery rate after high-temperature storage, a high capacity retention rate, a low resistance increase rate, and a high gas generation reduction effect. In addition, referring to Table 3 above, the lithium secondary battery of the example also has low heat generation and provides high reliability at high temperatures.

[0516] However, referring to Table 3 above, Comparative Examples 7 to 9, which did not satisfy the composition of the electrode plate and electrolyte of the example, did not have a good effect compared to the example.

[0517]

[0518] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

Claims

1. An electrode plate comprising an active material for a lithium secondary battery, a binder, and a first additive of Formula 1; and an electrolyte, comprising The above electrolyte comprises a non-aqueous organic solvent; a lithium salt; and an additive, The above additive is a lithium secondary battery comprising one or more second additives selected from the following Chemical Formula 2, the following Chemical Formula 3, and the following Chemical Formula 4: [Chemical Formula 1] (In the above chemical formula 1, L 11 and L 12 Each is independently a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and A and B are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and At least one of A and B is a group represented by the following chemical formula 1-1 or the following chemical formula 1-2. [Chemical Formula 1-1] [Chemical Formula 1-2] (In the above Chemical Formula 1-1 and Chemical Formula 1-2, L 13 , L 14 , L 15 and L 16 Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group. [Chemical Formula 2] (In the above chemical formula 2, L 21 and L 22 Each is independently a single bond, a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group, and C and D are each independently a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and At least one of C and D is the following chemical formula 2-1. [Chemical Formula 2-1] (In the above chemical formula 2-1, X 21 , X 22 , X 23 and X 24 Each is independently a nitrogen atom (N) or CR, and X 21 , X 22 , X 23 and X 24 One or two of them are nitrogen atoms, and R is each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group). [Chemical Formula 3] (In the above chemical formula 3, R 21 and R 22 Each independently uses oxygen or CR 1 R 2 and, the above R 1 and R 2 Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group, and R 23 is a substituted or unsubstituted C1 to C5 alkylene group, a substituted or unsubstituted C1 to C5 alkyleneoxy group, a substituted or unsubstituted C2 to C5 alkenylene group, a substituted or unsubstituted C2 to C5 alkynylene group, or a substituted or unsubstituted C6 to C20 arylene group). [Chemical Formula 4] (In the above chemical formula 4, X is a fluoro group, chloro group, bromo group, or iodo group, and R 11 to R 16 Each is independently hydrogen, a cyano group, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C2 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C20 aryl group, or a substituted or unsubstituted C2 to C20 heteroaryl group, and n is an integer of 0 or 1).

2. In claim 1, the first additive is a lithium secondary battery represented by the following chemical formula 1-3: [Chemical Formula 1-3] In the above chemical formula 1-3, L 11 and L 12 Each is an independently substituted or unsubstituted C2 to C5 alkylene group, and L 3A , L 3B , L 4A and L 4B Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group.

3. A lithium secondary battery according to claim 1, wherein the first additive comprises one or more of the following chemical formulas 1-4 and 1-5: [Chemical Formula 1-4] [Chemical Formula 1-5] .

4. A lithium secondary battery according to claim 1, wherein the first additive is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the active material for the lithium secondary battery.

5. In claim 1, the active material for the lithium secondary battery comprises a lithium nickel-based oxide, wherein the lithium secondary battery is a lithium secondary battery.

6. A lithium secondary battery according to claim 1, wherein the second additive is included in an amount of 0.05 to 5 weight% relative to the total amount of the electrolyte.

7. A lithium secondary battery according to claim 1, wherein the second additive comprises a compound of the formula 2.

8. In claim 7, a lithium secondary battery in which C and D are each independently of the following chemical formulas 2-2, 2-3, or 2-4: [Chemical Formula 2-2] [Chemical Formula 2-3] [Chemical Formula 2-4] (In the above chemical formulas 2-2, 2-3, and 2-4, R a , R b , and R c Each is independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C3 to C10 cycloalkyl group).

9. A lithium secondary battery according to claim 7, wherein the second additive comprises one or more of the following chemical formulas 2-5 to 2-8: [Chemical Formula 2-5] [Chemical Formula 2-6] [Chemical Formula 2-7] [Chemical Formula 2-8] .

10. A lithium secondary battery according to claim 7, wherein the non-aqueous organic solvent is a mixture comprising ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 40: 30 to 80.

11. A lithium secondary battery according to claim 1, wherein the second additive comprises a compound of the formula 3.

12. In Clause 11, the above R 21 , R 22 A lithium secondary battery in which at least one of the components is oxygen.

13. A lithium secondary battery according to claim 11, wherein the second additive comprises one or more of the following chemical formulas 3-1 to 3-7: [Chemical Formula 3-1] [Chemical Formula 3-2] [Chemical Formula 3-3] [Chemical Formula 3-4] [Chemical Formula 3-5] [Chemical Formula 3-6] [Chemical Formula 3-7] .

14. A lithium secondary battery according to claim 11, wherein the non-aqueous organic solvent is a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 30: 40 to 80.

15. A lithium secondary battery according to claim 11, wherein the second additive comprises a compound of the formula 3.

16. A lithium secondary battery according to claim 15, wherein the second additive comprises one or more of the following chemical formulas 4-2 and 4-3. [Chemical Formula 4-2] [Chemical Formula 4-3] (In the above chemical formulas 4-2 and 4-3, R 11 to R 16 Each is identical to what is defined in Chemical Formula 4 above).

17. A lithium secondary battery according to claim 15, wherein the second additive comprises one or more of the following chemical formulas 4-4 to 4-8: [Chemical Formula 4-4] [Chemical Formula 4-5] [Chemical Formula 4-6] [Chemical Formula 4-7] [Chemical Formula 4-8] .

18. A lithium secondary battery according to claim 15, wherein the non-aqueous organic solvent is a mixture containing ethylene carbonate (EC): ethylmethyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of 10 to 30: 5 to 20: 60 to 80.

19. In paragraph 1, the concentration of the lithium salt is 0.1M to 3.0M, and The above lithium salt is LiPF6, a lithium secondary battery.

20. A lithium secondary battery according to claim 1, wherein the electrode plate is a positive electrode, and the lithium secondary battery further comprises a negative electrode, and the negative electrode comprises a graphite and Si composite as a negative electrode active material.

21. A lithium secondary battery according to claim 20, wherein the Si composite : graphite is included in a weight ratio of 3 : 97 to 20 :

80.

22. In paragraph 1, the lithium secondary battery is a circular lithium secondary battery.

23. In paragraph 1, the lithium secondary battery is a lithium secondary battery having a driving voltage of 4.2V or higher.

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