Lithium secondary battery

Abstract

The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; a separator disposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte, wherein the positive electrode includes a positive electrode active material, the positive electrode active material includes an overlithiated manganese-rich oxide containing at least 50 mol% of Mn among all metals other than lithium and having a molar ratio of lithium to transition metals of greater than 1, and the non-aqueous electrolyte contains a lithium salt, a compound represented by chemical formula 1, and a compound represented by chemical formula 2.

Description

lithium secondary battery Cross-citation with related applications This application claims the benefit of priority to Korean Patent Application No. 10-2023-0126665, filed September 21, 2023, the entire contents of which are incorporated herein by reference. Technology field The present invention relates to a lithium secondary battery. Specifically, the present invention relates to a lithium secondary battery comprising a lithium manganese-rich oxide as a positive electrode active material. Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing. The above lithium secondary battery is generally composed of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte that serves as a medium for transferring lithium ions, and a separator. At this time, carbon-based active materials, silicon-based active materials, etc. can be used as the negative electrode active material. In addition, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel-cobalt-manganese composite oxide can be used as the positive electrode active material. Recently, lithium manganese-rich oxides (LiMnO) have been attracting attention as next-generation cathode active materials. LiMnO has the advantage of high capacity due to its high content of manganese (Mn), which is relatively inexpensive and abundant. However, its application is limited by several issues: Reactive oxygen generated by phase transformation of the cathode active material during activation (formation) and charge / discharge processes can aggravate electrolyte decomposition and significantly increase gas production; and transition metals eluted from the cathode active material can deposit on the cathode, destroying the SEI film. These issues are particularly problematic during high-temperature and high-voltage operation. One object of the present invention is to solve the above-described problems, and to provide a lithium secondary battery including a lithium manganese-rich oxide as a positive electrode active material, which reduces gas generation during initial activation and charge / discharge, and suppresses the elution of transition metals from the positive electrode active material, thereby providing a lithium secondary battery having excellent high-temperature cycle characteristics and high-temperature storage characteristics. [1] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte; wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a perlithium manganese-rich oxide containing Mn of 50 mol% or more among all metals excluding lithium and a molar ratio of lithium to transition metal exceeding 1, and wherein the non-aqueous electrolyte comprises a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2. [Chemical Formula 1] In the above chemical formula 1, R1 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and n is an integer from 0 to 6, [Chemical Formula 2] In the above chemical formula 2, R2 is fluorine, an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, or an aryloxy group having 6 to 20 carbon atoms substituted with one or more fluorines, and R3 and R4 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. [2] The present invention provides a lithium secondary battery according to the above [1], wherein the lithium manganese-rich oxide includes a compound represented by the following chemical formula A. [Chemical Formula A] Li 1+s [Ni t Co u Mn v M 1 w ]O 2+z In the above chemical formula A, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 0.05≤s≤1, 0≤t≤0.5, 0≤u≤0.3, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. [3] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] and [2], the compound represented by the chemical formula 1 includes at least one selected from the group consisting of a compound represented by the following chemical formula 1-A and a compound represented by the following chemical formula 1-B. [Chemical Formula 1-A] [Chemical Formula 1-B] In the above chemical formulas 1-A and 1-B, R1 is as defined in the above chemical formula 1. [4] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [3], the compound represented by the chemical formula 1 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-9. [Chemical Formula 1-1] [Chemical Formula 1-2] [Chemical Formula 1-3] [Chemical Formula 1-4] [Chemical Formula 1-5] [Chemical Formula 1-6] [Chemical Formula 1-7] [Chemical Formula 1-8] [Chemical Formula 1-9] [5] The present invention provides a lithium secondary battery, wherein the compound represented by the chemical formula 1 is included in an amount of 0.01 wt% to 10 wt% based on the weight of the non-aqueous electrolyte in at least one of the above [1] to [4]. [6] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [5], the compound represented by the chemical formula 2 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1 to 2-5. [Chemical Formula 2-1] [Chemical Formula 2-2] [Chemical Formula 2-3] [Chemical Formula 2-4] [Chemical Formula 2-5] [7] The present invention provides a lithium secondary battery in which, in at least one of the above [1] to [6], the compound represented by the above chemical formula 2 is included in the non-aqueous electrolyte at 5 to 40 wt%. [8] The present invention provides a lithium secondary battery in which the weight ratio of the compound represented by the chemical formula 1 and the compound represented by the chemical formula 2 is 0.01:99.1 to 50:50 in at least one of the above [1] to [7]. [9] The present invention is characterized in that in at least one of the above [1] to [8], the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2) are provided.

[0010] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [9], the non-aqueous electrolyte comprises an organic solvent, and the organic solvent comprises at least one selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0011] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0010] , the non-aqueous electrolyte further includes at least one additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, LiBOB (lithium bis-(oxalato)borate), LiODFB (lithium difluorooxalatoborate), TMSPa (Tris(trimethylsilyl phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite). The lithium secondary battery of the present invention uses a perlithium manganese-rich oxide as a positive electrode active material, and is characterized by using a compound represented by the above chemical formula 1 and a compound represented by the above chemical formula 2 as non-aqueous electrolyte components. The compound represented by the above chemical formula 1 is a coumarin-based compound, which scavenges reactive oxygen during initial activation, thereby preventing consumption of an organic solvent in a non-aqueous electrolyte and preventing gas generation due to decomposition of the organic solvent. In addition, the compound represented by the above chemical formula 2 is a sulfonamide-based compound, which ensures oxidation stability of a non-aqueous electrolyte, thereby suppressing battery degradation due to gas generation during charge and discharge. Accordingly, when the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 are used together, the initial activation of a lithium secondary battery including a perlithium manganese-rich oxide, gas generation during charge and discharge, and the elution of a transition metal from a positive electrode active material can be suppressed, so that the high-temperature cycle characteristics and high-temperature storage characteristics of the lithium secondary battery can be significantly improved. Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner. It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. Meanwhile, before explaining the present invention, unless otherwise specified, “*” in the present invention means a connected portion (bonding site) between the terminals of the same or different atoms or chemical formulas. In addition, in the description of "carbon atoms a to b" in the present specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "an alkyl group having 1 to 5 carbon atoms" refers to an alkyl group including 1 to 5 carbon atoms, i.e., CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2CH2CH2-, (CH3)2CHCH2CH2CH2-, etc. Additionally, in this specification, both alkyl groups and aryl groups may be substituted or unsubstituted. The above "substitution" means, unless otherwise defined, that at least one hydrogen bonded to carbon is replaced by an element other than hydrogen, for example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, a cycloalkynyl group having 3 to 12 carbon atoms, a heterocycloalkyl group having 3 to 12 carbon atoms, a heterocycloalkenyl group having 3 to 12 carbon atoms, a heterocycloalkynyl group having 2 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group, an aryl group having 6 to 20 carbon atoms, an aryl group having 2 to 20 carbon atoms, an alkyl ... It means substituted with a heteroaryl group having 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, etc. Hereinafter, the present invention will be described in more detail. The non-aqueous electrolyte and / or lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination between the technically possible configurations among the configurations below. lithium secondary battery The present invention relates to a lithium secondary battery. A lithium secondary battery according to the present invention comprises a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte; wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a perlithium manganese-rich oxide containing Mn of 50 mol% or more among all metals excluding lithium and a molar ratio of lithium to transition metal exceeding 1, and the non-aqueous electrolyte comprises a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2. [Chemical Formula 1] In the above chemical formula 1, R1 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and n is an integer from 0 to 6. [Chemical Formula 2] In the above chemical formula 2, R2 is fluorine, an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, or an aryloxy group having 6 to 20 carbon atoms substituted with one or more fluorines, and R3 and R4 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. The lithium secondary battery of the present invention uses a perlithium manganese-rich oxide as a positive electrode active material, and is characterized by using a compound represented by the above chemical formula 1 and a compound represented by the above chemical formula 2 as non-aqueous electrolyte components. The compound represented by the above chemical formula 1 is a coumarin-based compound, which scavenges reactive oxygen during initial activation, thereby preventing consumption of an organic solvent in a non-aqueous electrolyte and preventing gas generation due to decomposition of the organic solvent. In addition, the compound represented by the above chemical formula 2 is a sulfonamide-based compound, which ensures oxidation stability of a non-aqueous electrolyte, thereby suppressing battery degradation due to gas generation during charge and discharge. Accordingly, when the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 are used together, the initial activation of a lithium secondary battery including a perlithium manganese-rich oxide, gas generation during charge and discharge, and the elution of a transition metal from a positive electrode active material can be suppressed, so that the high-temperature cycle characteristics and high-temperature storage characteristics of the lithium secondary battery can be significantly improved. The lithium secondary battery includes a positive electrode; a negative electrode; a separator; and a non-aqueous electrolyte. Specifically, the lithium secondary battery includes a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte. The lithium secondary battery can be manufactured by housing an electrode assembly including the positive electrode; a negative electrode facing the positive electrode; and a separator interposed between the positive electrode and the negative electrode; in a battery case, and then injecting a non-aqueous electrolyte. (1) Bipolar The above positive electrode includes a positive electrode active material. The above-described positive electrode active material comprises a lithium manganese-rich oxide. The lithium manganese-rich oxide comprises manganese in an amount of 50 mol% or more among all metals excluding lithium, and the molar ratio of lithium to transition metal may exceed 1. The above lithium manganese-rich oxide is attracting attention as a next-generation high-capacity cathode active material, but its utilization is limited due to the structural deterioration unique to the material. Specifically, the reactive oxygen decomposed from the lithium manganese-rich oxide during initial activation decomposes and consumes the organic solvent (such as ethylene carbonate) contained in the non-aqueous electrolyte, thereby generating gaseous byproducts, which causes problems such as reduced life performance, increased resistance, and reduced safety. In addition, during the charge / discharge process of a lithium secondary battery containing the lithium manganese-rich oxide, the decomposition product of the lithium salt, HF, elutes the manganese in the lithium manganese-rich oxide, and thus, there is a problem that oxygen, specifically, reactive oxygen, is also decomposed from the lithium manganese-rich oxide in order to maintain the charge balance. The eluted manganese deposits on the cathode, destroying the SEI film. Furthermore, the reactive oxygen released during the charge / discharge process continuously decomposes and consumes the organic solvent in the non-aqueous electrolyte, increasing the production of gaseous byproducts. This consumption of the non-aqueous electrolyte, structural collapse of the perlithium manganese-rich oxide, and increased gaseous byproducts significantly degrade the lifespan, resistance characteristics, and safety of lithium secondary batteries. Furthermore, these problems are exacerbated under high-temperature, high-voltage conditions. In order to solve these problems, the lithium secondary battery according to the present invention is characterized by using a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2 in combination as non-aqueous electrolyte components. When the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 are used simultaneously, the generation of reactive oxygen during the initial activation process and the operation process of the lithium secondary battery is significantly suppressed, the structural collapse of the superlithium manganese-rich oxide is prevented, and the consumption of the organic solvent can be significantly prevented, thereby enabling the implementation of a lithium secondary battery with excellent high-temperature cycle characteristics, high-temperature storage characteristics, and safety. Such effects are difficult to implement in other lithium transition metal oxides in which the desorption of reactive oxygen is not a major problem, and rather, an increase in initial resistance and a decrease in life performance may become problems due to the use of the compounds of Chemical Formula 1 and Chemical Formula 2. The above lithium manganese-rich oxide may include a compound represented by the following chemical formula A. [Chemical Formula A] Li 1+s [Ni t Co u Mn v M 1 w ]O 2+z In the above chemical formula A, M 1is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 0.05≤s≤1, 0≤t≤0.5, 0≤u≤0.3, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. Preferably, in the chemical formula X, 0.05≤s≤1.0, 0.1≤t≤0.5, 0≤u≤0.1, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. More preferably, in the chemical formula X, 0.10≤s≤0.50, 0.1≤t≤0.5, 0≤u≤0.1, 0.6≤v<1.0, 0≤w≤0.1, 0≤z≤0.50 may be satisfied. More specifically, the lithium manganese-rich oxide may include a compound represented by the following chemical formula A-1. [Chemical Formula A-1] X Li2MnO3·(1-X)Li[Ni 1-y-z-w Mn y Co z M 1 w ]O2 In the above chemical formula A-1, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. In addition, in the chemical formula Y, 0.1≤X≤0.5, 0.5≤y<1, 0≤z≤0.3, 0≤w≤0.2 may be satisfied, preferably 0.2≤X≤0.5, 0.5≤y<1, 0≤z≤0.1, 0≤w≤0.2, more preferably 0.3≤X≤0.5, 0.6≤y<1, 0≤z≤0.1, 0≤w≤0.2. The positive electrode may include a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. In this case, the positive electrode active material may be included in the positive electrode active material layer. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the positive electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and an aluminum-cadmium alloy, preferably aluminum. The thickness of the above positive electrode collector may typically be 3 to 500 μm. The above-described positive electrode current collector may also form fine irregularities on its surface to enhance the bonding strength of the positive electrode active material. For example, the above-described positive electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric. The above positive electrode active material layer may be disposed on at least one side of the positive electrode current collector, specifically on one side or both sides of the positive electrode current collector. The above-mentioned positive electrode active material may be included in the positive electrode active material layer at 80 wt% to 99 wt%, preferably 92 wt% to 98.5 wt%, taking into account sufficient capacity of the positive electrode active material. Description of other positive electrode active materials is omitted as it has been described above. The above positive electrode active material layer may further include a binder and / or a conductive material together with the positive electrode active material. The above binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and specifically, may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride. The above binder may be included in the positive electrode active material layer at 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%, in order to sufficiently secure binding force between components such as the positive electrode active material. The conductive material may be used to assist and improve conductivity in a secondary battery, and is not particularly limited as long as it has conductivity without causing chemical changes. Specifically, the positive electrode conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, etc.; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably, in terms of improving conductivity, may include carbon nanotubes. The above-mentioned conductive material may be included in the positive electrode active material layer at 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%, in order to sufficiently secure electrical conductivity. The thickness of the positive electrode active material layer may be 30 µm to 400 µm, preferably 40 µm to 110 µm. The above positive electrode can be manufactured by coating a positive electrode slurry containing a positive electrode active material and optionally a binder, a conductive material, and a solvent for forming a positive electrode slurry on the positive electrode current collector, and then drying and rolling. The solvent for forming the positive electrode slurry may include an organic solvent such as NMP (N-methyl-2-pyrrolidone). The solid content of the positive electrode slurry may be 40 wt% to 90 wt%, specifically 50 wt% to 80 wt%. (2) Cathode The above cathode may be opposite to the above anode. The above negative electrode includes a negative electrode active material. The above negative electrode active material is a material capable of reversibly inserting / de-inserting lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, (semi)metal-based active materials, and lithium metal, and specifically may include at least one selected from among carbon-based active materials and (semi)metal-based active materials. The above carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include at least one selected from the group consisting of artificial graphite and natural graphite. The average particle diameter (D) of the above carbon-based active material 50 ) may be 10㎛ to 30㎛, preferably 15㎛ to 25㎛, in order to ensure structural stability during charging and discharging and reduce side reactions with the electrolyte. Specifically, the (semi-)metal-based active material may include at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium with at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); lithium vanadium oxide; etc. More specifically, the (semi)metal-based active material may include a silicon-based active material. The above silicon-based active material is SiO x It may include a compound represented by (0≤x<2) and a silicon-carbon composite. In the case of SiO2, since it does not react with lithium ions and thus cannot store lithium, it is preferable that x is within the above range, and more preferably, the silicon-based active material may be SiO. The average particle diameter (D) of the above silicon-based active material 50 ) may be 1㎛ to 30㎛, preferably 2㎛ to 15㎛, in order to reduce side reactions with the electrolyte while ensuring structural stability during charging and discharging. The above negative electrode may include a negative electrode current collector; and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. In this case, the negative electrode active material may be included in the negative electrode active material layer. The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy. The above negative electrode current collector may typically have a thickness of 3 to 500 μm. The above-described negative electrode current collector may have fine irregularities formed on its surface to enhance the bonding strength of the negative electrode active material. For example, the above-described negative electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric. The above negative electrode active material layer may be disposed on at least one side of the negative electrode current collector, specifically, one side or both sides of the negative electrode current collector. The above negative active material may be included in the negative active material layer in an amount of 60 wt% to 99 wt%, preferably 75 wt% to 95 wt%. Description of other positive electrode active materials is omitted as it has been described above. The above negative electrode active material layer may further include a binder and / or a conductive material together with the negative electrode active material. The above binder is used to improve the performance of the battery by improving the adhesion between the negative electrode active material layer and the negative electrode current collector, and may include, for example, at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, and materials in which hydrogens of these are substituted with Li, Na, Ca, etc., and may also include various copolymers thereof. May include. The above binder may be included in the negative electrode active material layer in an amount of 0.5 wt% to 10 wt%, preferably 1 wt% to 5 wt%. The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, and the like; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. The above conductive material may be included in the negative electrode active material layer in an amount of 0.5 wt% to 10 wt%, preferably 1 wt% to 5 wt%. The thickness of the negative electrode active material layer may be 10 µm to 200 µm, preferably 20 µm to 150 µm. The above negative electrode can be manufactured by coating a negative electrode slurry including a negative electrode active material, a binder, a conductive material, and / or a solvent for forming a negative electrode slurry on at least one surface of a negative electrode current collector, and then drying and rolling. The solvent for forming the negative electrode slurry may include at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate dispersion of the negative electrode active material, binder, and / or conductive agent, for example. The solid content of the negative electrode slurry may be 30 wt% to 80 wt%, specifically 40 wt% to 70 wt%. (3) Membrane The above separator may be interposed between the positive electrode and the negative electrode. In addition, as the separator, a conventional porous polymer film that has been conventionally used as a separator, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, may be used alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure. (4) Non-aqueous electrolyte The non-aqueous electrolyte according to the present invention comprises a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2. The non-aqueous electrolyte may further comprise an organic solvent and an additive, as appropriate. In this case, the organic solvent and the additive are used as terms to distinguish them from the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2. 1) Lithium salt As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation. For example, the lithium salt may be Li as a cation. + , and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3- , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may include at least one selected from the group consisting of . Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI ((LiN(SO2F)2), and LiBETI (LiN(SO2CF2CF3)2). The lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, specifically at a concentration of 0.8 M to 4 M, and more specifically at a concentration of 0.8 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the lithium ion yield (Li + The output characteristics of the battery can be improved by improving the transference number and the degree of dissociation of lithium ions. Alternatively, the lithium salt may be included in the non-aqueous electrolyte as a component of the non-aqueous electrolyte, for example, a compound represented by chemical formula 1, a compound represented by chemical formula 2, optionally an organic solvent, and a remainder excluding additives. 2) Compound represented by chemical formula 1 The non-aqueous electrolyte of the present invention comprises a compound represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, R1 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and n is an integer from 0 to 6. The compound represented by the above chemical formula 1 is a coumarin-based compound that can capture reactive oxygen released from lithium manganese-rich oxide during initial activation. Accordingly, the use of the compound represented by the above chemical formula 1 can prevent decomposition of organic solvents and increased generation of gaseous byproducts, which are concerns when reactive oxygen is generated during the initial activation process. In addition, in the case of the compound represented by the above chemical formula 1, upon initial activation, it can be opened to form a polymer-type film of the polyethylene oxide system on the electrode, and this polymer-type film has excellent flexibility and recoverability. In particular, since an inorganic-type film such as LiF formed by the decomposition of the compound represented by the chemical formula 2 described below is complexed with the polymer-type film, the non-aqueous electrolyte of the present invention contains both organic and inorganic components, and can form a film with improved flexibility, recoverability, and durability on the electrode, thereby further improving high-temperature life characteristics and high-temperature storage characteristics. However, the compound represented by the above chemical formula 1, aside from being able to remove reactive oxygen in the initial activation process, is not effective in removing reactive oxygen generated during charge / discharge or storage of a lithium secondary battery. The reactive oxygen generated during charge / discharge or storage of a lithium secondary battery generates H2O as a by-product of the reaction with the electrolyte, and the H2O decomposes the lithium salt to generate HF, and the HF dissolves manganese in the perlithium manganese-rich oxide and desorbs oxygen, which may accelerate the deterioration of life performance and storage performance. In order to solve this problem, the present invention uses the compound represented by the above chemical formula 2 together with the compound represented by the above chemical formula 1 to remove HF generated during charge / discharge, storage, etc., thereby blocking the possibility of generation of reactive oxygen during charge / discharge, storage, etc. of a lithium secondary battery. Accordingly, the present invention can simultaneously improve the life performance, storage performance, and safety of a lithium secondary battery by controlling the generation of reactive oxygen, which is particularly problematic in lithium manganese-rich oxide, by using the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 simultaneously, and in particular, can significantly improve the life performance, storage performance, and safety when operating at high temperature and high voltage. In the above chemical formula 1, R1 can be specifically a halogen (the halogen can be selected from F, Cl, Br, and I, and can be specifically F), a nitrile group, a propargyl group, an ester group, an ether group, or a combination of two or more thereof. Such a substituent can improve the reducibility of the compound represented by the above chemical formula 1, and can also realize the effects of smooth formation of an SEI film and improved lithium ion transfer performance, along with the ability to capture reactive oxygen. In the above chemical formula 1, n may be an integer selected from 0 to 6, specifically an integer selected from 1 to 6, and more specifically n may be 1. In the above chemical formula 1, when n is 2 or more, each R1 may be the same or different. Specifically, the compound represented by the above chemical formula 1 may include at least one selected from the group consisting of a compound represented by the following chemical formula 1-A and a compound represented by the following chemical formula 1-B. [Chemical Formula 1-A] [Chemical Formula 1-B] In the above chemical formulas 1-A and 1-B, R1 is as defined in the above chemical formula 1. The compounds represented by the above chemical formulas 1-A and 1-B have structures in which substituents exist at positions 3 and 7 (based on IUPAC nomenclature) of the ring structure, respectively. In this case, it is preferable to synthesize at positions like the above compared to other substitution positions in that it is advantageous. Specifically, the compound represented by the above formula 1 may include at least one selected from the group consisting of compounds represented by the following formulas 1-1 to 1-9. The compound represented by the above formula 1 may specifically include at least one selected from the group consisting of compounds represented by the following formulas 1-1 to 1-4, 1-6, and 1-8, in that it is more smoothly reduced to the negative electrode and is more advantageous in forming an SEI film, and more specifically, it may include at least one selected from the group consisting of compounds represented by the following formulas 1-1 and 1-2, and even more specifically, it may include a compound represented by the following formula 1-1. [Chemical Formula 1-1] [Chemical Formula 1-2] [Chemical Formula 1-3] [Chemical Formula 1-4] [Chemical Formula 1-5] [Chemical Formula 1-6] [Chemical Formula 1-7] [Chemical Formula 1-8] [Chemical Formula 1-9] The compound represented by the above chemical formula 1 may be included in the non-aqueous electrolyte in an amount of 0.01 wt% to 10 wt%, specifically 0.05 wt% to 5 wt%, more specifically 0.1 wt% to 1 wt%, and more specifically 0.3 wt% to 0.7 wt%. The content of the compound represented by the above chemical formula 1 can sufficiently exhibit the reactive oxygen capture effect occurring during the initial activation described above, and can prevent concerns about increased resistance when added in excess. 3) Compound represented by chemical formula 2 The non-aqueous electrolyte according to the present invention comprises a compound represented by the following chemical formula 2. [Chemical Formula 2] In the above chemical formula 2, R2 is fluorine, an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, or an aryloxy group having 6 to 20 carbon atoms substituted with one or more fluorines, and R3 and R4 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. The compound represented by the above chemical formula 2 is a sulfonamide compound containing a fluorine-containing substituent, and when included in a non-aqueous electrolyte, it can significantly improve the oxidation stability of the solvent. Specifically, the compound represented by the above chemical formula 2 improves the oxidation stability of the solvent during the charge / discharge process rather than the initial activation process, thereby preventing electrolyte side reactions and significantly reducing the resulting gas generation. Therefore, the non-aqueous electrolyte according to the present invention significantly suppresses gas generation during the initial activation process as well as the battery operation process, and as a result, can significantly improve the high-temperature storage characteristics, high-temperature life characteristics, and resistance characteristics of a lithium secondary battery including a perlithium manganese-rich oxide. If the compound represented by the above chemical formula 2 has a minimal oxygen capture effect during the initial activation, it cannot prevent the generation of reactive oxygen, which is a problem during the initial activation, and therefore, the intended effect of the present invention cannot be achieved without using the compound represented by the chemical formula 1 in combination with the compound represented by the chemical formula 2. In addition, the compound represented by the above chemical formula 2 contains fluorine, and can provide an inorganic film such as LiF to the electrode upon decomposition. Since the inorganic film is complexed with a polymer film derived from the compound represented by the above chemical formula 1, a film with improved flexibility, resilience, and durability can be formed on the electrode, thereby further improving high-temperature lifespan characteristics and high-temperature storage characteristics. R2 is fluorine, an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, or an aryloxy group having 6 to 20 carbon atoms substituted with one or more fluorines, and may be specifically fluorine or an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, and may be even more specifically fluorine or an alkoxy group having 1 to 5 carbon atoms substituted with one or more fluorines, and may be even more specifically fluorine, CF3O-, CF3CF2O-, or CF3CH2O-, and may be even more specifically fluorine or CF3CH2O-. R3 and R4 can be independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and specifically hydrogen or an alkyl group having 1 to 5 carbon atoms, more specifically an alkyl group having 1 to 5 carbon atoms, and even more specifically a methyl group. Specifically, the compound represented by the above formula 2 may include at least one selected from the group consisting of compounds represented by the following formulas 2-1 to 2-5. More specifically, the compound represented by the above formula 2 may include at least one selected from the group consisting of compounds represented by the following formulas 2-1 to 2-3. Even more specifically, the compound represented by the above formula 2 may include at least one selected from the group consisting of compounds represented by the following formulas 2-1 and 2-2. [Chemical Formula 2-1] [Chemical Formula 2-2] [Chemical Formula 2-3] [Chemical Formula 2-4] [Chemical Formula 2-5] The compound represented by the above chemical formula 2 may be included in the non-aqueous electrolyte in an amount of 5 wt% to 40 wt%, specifically 8 wt% to 30 wt%, more specifically 10 wt% to 25 wt%, and even more specifically 15 wt% to 22 wt%. When the compound represented by the above chemical formula 2 is included in the above content range, the oxidation stability of the solvent can be sufficiently improved, while problems such as a decrease in electrode impregnation due to an increase in the viscosity of the non-aqueous electrolyte caused by excessive addition and a decrease in the solubility of non-aqueous electrolyte components such as additives can be prevented. Meanwhile, when the content of the compound represented by the above chemical formula 2 in the non-aqueous electrolyte is expressed as a volume percentage, the compound represented by the chemical formula 2 may be present in the non-aqueous electrolyte at 5% to 40% by volume, specifically 12% to 25% by volume. The weight ratio of the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 may be 0.01:99.99 to 50:50, specifically 0.1:99.9 to 40:60, more specifically 0.2:99.8 to 30:70, even more specifically 0.5:99.5 to 10:90, even more specifically 0.5:99.5 to 7:93, and even more specifically 2:98 to 4:96. When within the above range, an excellent overall gas reduction effect can be exhibited during the aforementioned initial activation and battery operation process. 4) Organic solvents The above non-aqueous electrolyte may further include an organic solvent along with the above-mentioned components. The organic solvent mentioned above is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery can be minimized. The organic solvent may be included in the non-aqueous electrolyte as a remainder excluding the lithium salt, the compound represented by the chemical formula 1, the compound represented by the chemical formula 2, and other additives optionally included. Specifically, the organic solvent may include at least one selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent. Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof. The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent having a high dielectric constant and thus capable of dissociating a lithium salt in an electrolyte well, and specifically may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and more specifically may include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically may include ethylene carbonate (EC). In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may specifically include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and more specifically, may include at least one selected from the group consisting of ethylmethyl carbonate (EMC) and diethyl carbonate (DEC), and even more specifically, may include ethylmethyl carbonate (EMC) and diethyl carbonate (DEC). When the linear carbonate-based organic solvent includes ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), the weight ratio of the ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) may be 50:50 to 99:1, specifically 75:25 to 95:5, and more specifically 80:20 to 90:10. Specifically, the organic solvent may include a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. When the organic solvent includes a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, the weight ratio of the compound represented by the chemical formula 2 and the organic solvent may be 5:95 to 45:55, specifically 10:90 to 35:65, and more specifically 15:85 to 25:75. When within the above range, the effect of improving the oxidation stability of the solvent may be further enhanced. When the organic solvent includes a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, the weight ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be 10:90 to 50:50, specifically 20:80 to 40:60. The linear ester organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. In addition, the cyclic ester organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. Meanwhile, the organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes as needed. For example, at least one organic solvent among an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent may be additionally included. As the above ether solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto. The above glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and is a solvent with low reactivity with metals, and may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto. The above nitrile solvent may be at least one selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto. 5) Additives The above non-aqueous electrolyte may further include additives in addition to the aforementioned components. Specifically, the additive may be at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, lithium difluorooxalatoborate (LiODFB), lithium bis-(oxalato)borate (LiBOB), 3-trimethoxysilanyl-propyl-N-aniline (TMSPa), and tris(trimethylsilyl) phosphate (TMSPi). The above additive may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 15 wt%. There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape. Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims. Examples and Comparative Examples Example 1 (Manufacture of non-aqueous electrolyte) A non-aqueous electrolyte was prepared by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. (Lithium secondary battery manufacturing) Cathode active material (Li 1.35 [Ni 0.360 Co 0.005 Mn 0.635 ]O2, lithium manganese-rich oxide): conductive material (carbon nanotube): binder (polyvinylidene fluoride) were added to the solvent N-methyl-2-pyrrolidone (NMP) in a weight ratio of 96.0:1.5:2.5 to prepare a positive electrode mixture slurry (solid content 65 wt%). The positive electrode mixture slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 12 μm, and dried and roll pressed to prepare a positive electrode. A negative electrode mixture slurry (solid content 50 wt%) was prepared by adding a negative electrode active material (a mixture of artificial graphite and natural graphite in a weight ratio of 50.3:49.7): conductive agent (carbon black): binder (styrene-butadiene rubber) to distilled water as a solvent in a weight ratio of 96.7:1.0:2.3. The negative electrode mixture slurry was applied to one surface of an 8 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode. A polyethylene porous film separator was interposed between the positive and negative electrodes manufactured above in a dry room, and then the non-aqueous electrolyte manufactured above was injected to manufacture a secondary battery. Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 1.0:18.5:14.0:20.0:39.0:7.5. Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.1:18.5:14.0:20.0:39.7:7.7. Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:27.0:14.0:20.0:31.0:7.5. Example 5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:9.4:14.2:20.6:47.7:7.6. Example 6 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-1, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Example 7 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by the above chemical formula 1-2, the compound represented by the above chemical formula 2-2, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Example 8 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-3, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Example 9 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-4, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Example 10 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-6, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Example 11 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used by mixing the compound represented by the above chemical formula 1-8, the compound represented by the above chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5. Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte prepared by mixing LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 14.5:21.0:56.8:7.7 was used. Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts, represented by the above chemical formula 1-2, in a weight ratio of 0.5:14.5:20.9:56.4:7.7. Comparative Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 18.6:14.1:20.4:39.4:7.5, as represented by the above chemical formula 2-1. Experimental Example 1: Evaluation of High-Temperature Cycle Charge-Discharge Performance The lithium secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 3 above were charged to 4.35 V, 1 / 20 C at 45° C. under CC / CV, 0.33 C conditions using an electrochemical charger / discharger, and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, and 150 cycles of charge / discharge were performed, and the capacity retention rate, resistance increase rate, gas generation amount, and metal elution amount were evaluated as follows. Experimental Example 1-1: Capacity Retention Rate Evaluation After charging and discharging under the above conditions, the capacity retention rate was calculated using the formula below, and the results are shown in Table 1 below. Capacity retention rate (%) = {(discharge capacity after 150 cycles / discharge capacity after 1 cycle)} × 100 Experimental Example 1-2: Evaluation of Resistance Increase Rate After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger and discharger, the SOC was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse was applied. After 150 cycles of charge and discharge, the resistance after 150 cycles was calculated using the same method as above, and the resistance increase rate was calculated using the equation below, and the results are shown in Table 1 below. Resistance increase rate (%) = (Resistance after 150 cycles - Initial resistance) / Initial resistance × 100 Experimental Example 1-3: Gas Emission Evaluation After charging and discharging under the above conditions, the amount of gas generated was measured using gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 1 below. Experimental Example 1-4: Evaluation of Metal Elution Amount After charging and discharging under the above conditions, the concentration of the total metal dissolved in the electrolyte was measured using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). The amount of metal measured using ICP analysis is shown in Table 1 below. Experimental Example 1-1 Experimental Example 1-2 Experimental Example 1-3 Experimental Example 1-4 Capacity retention rate (%) Resistance increase rate (%) Gas generation amount (㎕) Metal elution amount (ppm) Example 195.314.74200230 Example 294.116.84550250 Example 393.518.74600240 Example 493.120.14750260 Example 592.424.34950310 Example 691.823.84800275 Example 792.119.94900320 Example 890.519.34650295 Example 989.225.34500340 Example 1091.724.16400380 Example 1192.121.37500410 Comparative Example 168.335.520150590 Comparative Example 279.959.715850510 Comparative Example 383.848.914680495 Referring to Table 1, it can be confirmed that the lithium secondary batteries of Examples 1 to 11, which use lithium manganese-rich oxide as a cathode active material and include both compounds represented by Chemical Formula 1 and Chemical Formula 2 in the non-aqueous electrolyte, exhibit superior life performance, resistance reduction effect, low gas generation, and low metal elution during cycle charge and discharge compared to Comparative Examples 1 to 3, which do not. Experimental Example 2: Evaluation of High-Temperature Storage Performance The lithium secondary batteries manufactured in Examples 1 to 11 and Comparative Examples 1 to 3 above were charged to 4.35 V, 1 / 20 C under CC / CV, 0.33 C conditions at 25°C and discharged to 2.5 V at 0.33 C to perform initial charging and discharging. Afterwards, they were charged to 4.35 V, 1 / 20 C under CC / CV, 0.33 C conditions at 25°C and stored at 60°C for 8 weeks. Experimental Example 2-1: Capacity Retention Rate Evaluation After storage, the secondary batteries were charged to 4.35 V, 1 / 20 C at 25°C under CC / CV, 0.33 C conditions and discharged to 2.5 V at 0.33 C. The capacity retention rate was evaluated according to the following equation, and the results are shown in Table 2 below. Capacity retention rate (%) = (Discharge capacity after 8 weeks of storage / Initial discharge capacity) × 100 Experimental Example 2-2: Resistance Increase Rate Evaluation During the initial charge and discharge, after checking the capacity at room temperature, the battery was charged to SOC 50 based on the discharge capacity, discharged for 10 seconds with a 3C current, and the resistance was measured based on the voltage drop difference at this time, which was used as the initial resistance. After 8 weeks of storage at 60℃, the resistance was measured using the same method, which was used as the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 2 below. Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) × 100 Experimental Example 2-3: Gas Emission Evaluation After storage under the above conditions, the amount of gas generated was measured using gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 2 below. Experimental Example 2-4: Evaluation of Metal Elution Amount After storage under the above conditions, the concentration of the total metal dissolved in the electrolyte was measured using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). The amount of metal measured using ICP analysis is shown in Table 2 below. Experimental Example 2-1 Experimental Example 2-2 Experimental Example 2-3 Experimental Example 2-4 Capacity retention rate (%) Resistance increase rate (%) Gas generation amount (㎕) Metal elution amount (ppm) Example 194.219.83800295 Example 293.824.84100325 Example 393.223.34250330 Example 492.422.84380320 Example 592.824.14870340 Example 691.825.84950365 Example 789.926.95870384 Example 892.324.14750350 Example 991.528.35500370 Example 1091.131.16350410 Example 1188.324.85900425 Comparative Example 143.845.88750485 Comparative Example 258.639.76700585 Comparative Example 361.841.86900655 Referring to Table 2, it can be confirmed that the lithium secondary batteries of Examples 1 to 11, which use lithium manganese-rich oxide as a cathode active material and include both compounds represented by Chemical Formula 1 and Chemical Formula 2 in the non-aqueous electrolyte, exhibit superior life performance, resistance reduction effect, low gas generation, and low metal elution during high-temperature storage, compared to Comparative Examples 1 to 3, which do not. Reference example Reference Example 1 (Manufacture of non-aqueous electrolyte) A non-aqueous electrolyte was prepared using the same method as in Example 1. (Lithium secondary battery manufacturing) Cathode active material (Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2): Conductive agent (carbon nanotube): Binder (polyvinylidene fluoride) was added to the solvent N-methyl-2-pyrrolidone (NMP) in a weight ratio of 96.7:1.2:2.3 to prepare a positive electrode mixture slurry (solid content 65 wt%). The positive electrode mixture slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 12 ㎛, and dried and roll pressed to prepare a positive electrode. A negative electrode mixture slurry (solid content 50 wt%) was prepared by adding a negative electrode active material (a mixture of artificial graphite and natural graphite in a weight ratio of 50.3:49.7): conductive agent (carbon black): binder (styrene-butadiene rubber) to distilled water as a solvent in a weight ratio of 96.7:1.0:2.3. The negative electrode mixture slurry was applied to one surface of an 8 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode. A polyethylene porous film separator was interposed between the positive and negative electrodes manufactured above in a dry room, and then the non-aqueous electrolyte manufactured above was injected to manufacture a secondary battery. Reference Example 2 A lithium secondary battery was manufactured in the same manner as in Reference Example 1, except that a non-aqueous electrolyte manufactured in the same manner as in Comparative Example 2 was used. Reference Example 3 A lithium secondary battery was manufactured in the same manner as in Reference Example 1, except that a non-aqueous electrolyte manufactured in the same manner as in Comparative Example 3 was used. Reference Experimental Example 1: Evaluation of High-Temperature Cycle Charge-Discharge Performance The lithium secondary batteries of Reference Examples 1 to 3 manufactured above were charged to 4.35 V, 1 / 20 C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions at 45°C, and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, and 150 cycles of charge / discharge were performed, and the capacity retention rate, resistance increase rate, gas generation amount, and metal elution amount were evaluated as follows. Reference Experimental Example 1-1: Capacity Retention Rate Evaluation After charging and discharging under the above conditions, the capacity retention rate was calculated using the formula below, and the results are shown in Table 3 below. Capacity retention rate (%) = {(discharge capacity after 150 cycles / discharge capacity after 1 cycle)} × 100 Reference Experimental Example 1-2: Resistance Increase Rate Evaluation After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger and discharger, the SOC was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse was applied. After 150 cycles of charge and discharge, the resistance after 150 cycles was calculated using the same method as above, and the resistance increase rate was calculated using the equation below, and the results are shown in Table 3 below. Resistance increase rate (%) = (Resistance after 150 cycles - Initial resistance) / Initial resistance × 100 Reference Experimental Example 2: Evaluation of High-Temperature Storage Performance The lithium secondary batteries of Reference Examples 1 to 3 manufactured above were charged to 4.35 V, 1 / 20 C under CC / CV, 0.33 C conditions at 25°C and discharged to 2.5 V at 0.33 C to perform initial charging and discharging. Afterwards, they were charged to 4.35 V, 1 / 20 C under CC / CV, 0.33 C conditions at 25°C and stored at 60°C for 8 weeks. Experimental Example 2-1: Capacity Retention Rate Evaluation After storage, the secondary batteries were charged to 4.35 V, 1 / 20 C at 25°C under CC / CV, 0.33 C conditions and discharged to 2.5 V at 0.33 C. The capacity retention rate was evaluated according to the following equation, and the results are shown in Table 3 below. Capacity retention rate (%) = (Discharge capacity after 8 weeks of storage / Initial discharge capacity) × 100 Experimental Example 2-2: Resistance Increase Rate Evaluation During the initial charge and discharge, after checking the capacity at room temperature, the battery was charged to SOC 50 based on the discharge capacity, discharged for 10 seconds with a 3C current, and the resistance was measured based on the voltage drop difference at this time, which was used as the initial resistance. After 8 weeks of storage at 60℃, the resistance was measured using the same method, which was used as the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 3 below. Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) × 100 Reference Experimental Example 1 Reference Experimental Example 21-11-22-12-2 Capacity Maintenance Rate (%) Resistance Increase Rate (%) Capacity Maintenance Rate (%) Resistance Increase Rate (%) Reference Example 189.841.882.338.7 Reference Example 293.728.492.826.8 Reference Example 392.826.193.824.3 Referring to Table 3, it can be confirmed that the lithium secondary battery of Reference Example 1, which applied the non-aqueous electrolyte containing the compounds represented by Chemical Formula 1 and Chemical Formula 2 according to the present invention to a positive electrode active material other than lithium manganese-rich oxide, showed a lower performance during cycle charge / discharge and high-temperature storage compared to Reference Examples 2 and 3, which included only one of the compounds represented by Chemical Formula 1 or Chemical Formula 2 in the non-aqueous electrolyte. It is thought that this result is because the positive electrode active materials used in Reference Examples 1 to 3 had less effect on the desorption of reactive oxygen, and the increase in resistance due to the combined use of the two compounds was more problematic.

Claims

1. Containing a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte; The above positive electrode includes a positive electrode active material, The above cathode active material comprises a lithium manganese-rich oxide containing Mn at 50 mol% or more among all metals excluding lithium, and a molar ratio of lithium to transition metal exceeding 1, The above non-aqueous electrolyte is a lithium secondary battery including a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2: [Chemical Formula 1] In the above chemical formula 1, R1 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and n is an integer from 0 to 6, [Chemical Formula 2] In the above chemical formula 2, R2 is fluorine, an alkyl group having 1 to 10 carbon atoms substituted with one or more fluorines, an alkoxy group having 1 to 10 carbon atoms substituted with one or more fluorines, or an aryloxy group having 6 to 20 carbon atoms substituted with one or more fluorines, and R3 and R4 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

2. In claim 1, The lithium secondary battery comprising the above lithium manganese-rich oxide is a compound represented by the following chemical formula A: [Chemical Formula A] Li 1+s [Ni t Co u Mr v M 1 w ]O 2+z In the above chemical formula A, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 0.05≤s≤1, 0≤t≤0.5, 0≤u≤0.3, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1.

3. In claim 1, A lithium secondary battery comprising at least one compound represented by the chemical formula 1 below selected from the group consisting of a compound represented by the chemical formula 1-A below and a compound represented by the chemical formula 1-B below: [Chemical Formula 1-A] [Chemical Formula 1-B] In the above chemical formulas 1-A and 1-B, R1 is as defined in the above chemical formula 1.

4. In claim 1, A lithium secondary battery comprising at least one compound represented by the above chemical formula 1 selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-9: [Chemical Formula 1-1] [Chemical Formula 1-2] [Chemical Formula 1-3] [Chemical Formula 1-4] [Chemical Formula 1-5] [Chemical Formula 1-6] [Chemical Formula 1-7] [Chemical Formula 1-8] [Chemical Formula 1-9] .

5. In claim 1, A lithium secondary battery, wherein the compound represented by the above chemical formula 1 is included in an amount of 0.01% to 10% by weight based on the weight of the non-aqueous electrolyte.

6. In claim 1, A lithium secondary battery comprising at least one compound represented by the above chemical formula 2 selected from the group consisting of compounds represented by the following chemical formulas 2-1 to 2-5: [Chemical Formula 2-1] [Chemical Formula 2-2] [Chemical Formula 2-3] [Chemical Formula 2-4] [Chemical Formula 2-5] .

7. In claim 1, A lithium secondary battery, wherein the compound represented by the above chemical formula 2 is included in the non-aqueous electrolyte at 5 to 40 wt%.

8. In claim 1, A lithium secondary battery in which the weight ratio of the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 is 0.01:99.1 to 50:

50.

9. In claim 1, The above lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2).

10. In claim 1, The above non-aqueous electrolyte contains an organic solvent, A lithium secondary battery, wherein the organic solvent comprises at least one selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

11. In claim 1, A lithium secondary battery, wherein the non-aqueous electrolyte further comprises at least one additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, LiBOB (lithium bis-(oxalato)borate), LiODFB (lithium difluorooxalatoborate), TMSPa (Tris(trimethylsilyl phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite).

Images