Nonaqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention provides a nonaqueous electrolyte comprising: a lithium salt; an organic solvent; and a compound represented by chemical formula 1. [Chemical formula 1] In chemical formula 1, each of R1 to R5 is independently any one selectred from the group consisting of H, F, a nitrile group, a C2-10 alkoxycarbonyl group, a C2-10 alkylcarbonyl group, a C1-10 alkyl group, a C2-10 alkenyl group and a C2-10 alkynyl group, and n is an integer of 1 to 5.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same [Cross-reference with related applications] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0126663, filed September 21, 2023, and Korean Patent Application No. 10-2024-0122725, filed September 9, 2024, the entire contents of which are incorporated herein by reference. [Technical Field] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery including the same. 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 and supply 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. High-capacity, high-power output, and long-life characteristics are becoming increasingly important, especially for lithium secondary batteries used in automotive applications. To increase the capacity of secondary batteries, high-nickel-content cathode active materials, which offer high energy density but low stability, can be used, or the batteries can be operated at high voltages. However, when a secondary battery is operated under the above conditions, as charge and discharge progress, the film formed on the surface of the positive / negative electrode or the electrode surface structure may deteriorate due to side reactions caused by deterioration of the electrolyte, and transition metal ions may be eluted from the surface of the positive electrode. In this way, the eluted transition metal ions are electro-deposited on the negative electrode, thereby lowering the passivation ability of the SEI, which causes the negative electrode to deteriorate. This deterioration phenomenon of secondary batteries tends to accelerate when the potential of the positive electrode increases or when the battery is exposed to high temperatures. In addition, when a lithium-ion battery is used continuously for a long time or is left at a high temperature, gas is generated, causing the thickness of the battery to increase, which is called swelling. It is known that the amount of gas generated at this time is determined by the state of the SEI. Therefore, to solve these problems, research and development are being conducted on methods to suppress the dissolution of metal ions from the positive electrode, form a stable SEI film on the negative electrode, reduce the swelling phenomenon of secondary batteries, and increase stability at high temperatures. As a result of conducting multifaceted research to solve the above problems, the present invention aims to provide an additive for a non-aqueous electrolyte that can suppress the deterioration of the positive electrode, reduce side reactions between the positive electrode and the electrolyte, and form a stable SEI film on the negative electrode. In addition, the present invention seeks to provide a non-aqueous electrolyte having improved stability at high temperatures by including the above-described non-aqueous electrolyte additive. In addition, the present invention aims to provide a lithium secondary battery having improved high-temperature cycle characteristics and high-temperature storage characteristics by including the non-aqueous electrolyte, thereby improving overall performance. [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt; an organic solvent; and a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 to R5 are each independently any one selected from the group consisting of H, F, a nitrile group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms, and n is any one of the integers 1 to 5. [2] The present invention can provide a non-aqueous electrolyte in which the compound of the chemical formula 1 in the above [1] is a compound represented by the following chemical formula 1-1. [Chemical Formula 1-1] In the above chemical formula 1-1, n is any integer from 1 to 5. [3] The present invention can provide a non-aqueous electrolyte in which, in the above [1], the compound of the chemical formula 1 is any one selected from the group consisting of compounds represented by the following chemical formulas 1-2a to 1-2f. [Chemical Formula 1-2a] [Chemical Formula 1-2b] [Chemical Formula 1-2c] [Chemical Formula 1-2d] [Chemical Formula 1-2e] [Chemical Formula 1-2f] [4] The present invention can provide a non-aqueous electrolyte in which the compound of the chemical formula 1 is included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte in any one of the above [1] to [3]. [5] The present invention can provide a non-aqueous electrolyte in which the lithium salt is included in a concentration of 0.5 M to 2.0 M in any one of the above [1] to [4]. [6] The present invention is any one of the above [1] to [5], wherein the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10, LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2. [7] The present invention can provide a non-aqueous electrolyte comprising at least one organic solvent 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, in any one of the above [1] to [6]. [8] The present invention can provide a non-aqueous electrolyte further comprising, as an additive, at least one compound selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds in any one of the above [1] to [7]. [9] The present invention can provide a lithium secondary battery comprising a positive electrode; a negative electrode; and a non-aqueous electrolyte of any one of [1] to [7].

[0010] The present invention can provide a lithium secondary battery in which, in the above [9], the positive electrode is a lithium nickel-based oxide represented by the following [chemical formula 2] as a positive electrode active material. [Chemical Formula 2] Li x Ni a Co b M 1 c M 2 d O2 In the above chemical formula 2, M 1 is Mn, Al or a combination thereof, and M 2is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, and 0.8≤x≤1.2, 0.8≤a<1, 0 <b<0.2, 0<c<0.2, 0≤d≤0.1이다.

[0011] The present invention, in the above [9] or

[0010] , the negative electrode is SiO as a negative electrode active material. x A lithium secondary battery including (0≤x<2) can be provided. The compound represented by the above chemical formula 1 provided as an additive for a non-aqueous electrolyte of the present invention has coumarin as its basic structure. The compound with the coumarin structure has strong reducibility at the negative electrode, and thus, the cyclic structure rapidly undergoes a ring-opening reaction in the initial negative electrode film formation reaction. The resulting polyethylene oxide (PEO) polymer film has the characteristic of high elasticity. Therefore, even in lithium secondary batteries containing silicon-based negative electrode active materials that undergo extreme volume changes during charge and discharge, the film has excellent durability and thus excellent life characteristics. In addition, the compound represented by the chemical formula 1 of the present invention can form a radical to promote a reduction reaction of organic solvents or other additives contained in a non-aqueous electrolyte, thereby quickly forming a film with excellent durability. Furthermore, the compound represented by chemical formula 1 of the present invention is BF3 substituted at position 1. - It is possible to form a film containing an inorganic component such as LiF between polymeric organic films. Therefore, the film formed by the compound of chemical formula 1 becomes an organic / inorganic composite film and has excellent durability even when exposed to high temperatures or high voltages. In addition, the compound represented by chemical formula 1 of the present invention is BF3 substituted at position 1. -It exhibits the characteristics of a Lewis acid and can trap anions present in the electrolyte. As a result, it can stabilize the anions in the electrolyte, which are Lewis bases, thereby suppressing the structural deformation of the negative electrode film, thereby improving the high-temperature storage characteristics of lithium secondary batteries. In addition, the reduction product in the electrolyte and the BF3 substituted at the 1st position of the compound represented by the chemical formula 1 - Since the interfacial adhesion at the negative electrode is strengthened by forming a BO bond, the strength of the film derived from the compound of chemical formula 1 is strengthened. As a result, the durability of the film is excellent even in lithium secondary batteries containing silicon-based negative electrode active materials that undergo extreme volume changes during charge and discharge, resulting in excellent life characteristics. Therefore, by suppressing the deterioration of the passivation ability of SEI at high temperatures, the deterioration of the negative electrode can be prevented, thereby improving the life characteristics of the battery. That is, by using the non-aqueous electrolyte of the present invention including the compound of the above chemical formula 1, an electrode-electrolyte interface that is stable even at high temperatures and has low resistance can be formed, so that high-temperature cycle characteristics and high-temperature storage characteristics are improved, and a lithium secondary battery with improved overall performance can be implemented. 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. 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, "alkylene group having 1 to 5 carbon atoms" refers to an alkylene group including 1 to 5 carbon atoms, i.e., -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, and -CH(CH3)CH2CH2-. In addition, in the present specification, the alkyl group, alkenyl group, and alkynyl group may all be substituted or unsubstituted. The term "substituted" above, unless otherwise defined, means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, it means that it is replaced with a halogen atom such as F or Cl. 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. non-aqueous electrolyte The non-aqueous electrolyte of the present invention is characterized by including a compound of the following chemical formula 1 as an additive. [Chemical Formula 1] The compound of the above chemical formula 1 has coumarin as its basic structure. Compounds with a coumarin structure have strong reducibility at the negative electrode, so the cyclic structure rapidly undergoes a ring-opening reaction in the initial negative electrode film formation reaction. The resulting polyethylene oxide (PEO) polymer film has the characteristic of high elasticity. This results in excellent film durability and excellent life characteristics even in lithium secondary batteries containing silicon-based negative electrode active materials that undergo extreme volume changes during charge and discharge. In addition, the compound represented by the chemical formula 1 of the present invention can form a radical to promote a reduction reaction of organic solvents or other additives contained in a non-aqueous electrolyte, thereby quickly forming a film with excellent durability. Furthermore, the compound represented by chemical formula 1 of the present invention is BF3 substituted at position 1. - It is possible to form a film containing an inorganic component such as LiF between polymeric organic films. Therefore, the film formed by the compound of chemical formula 1 becomes an organic / inorganic composite film and has excellent durability even when exposed to high temperatures or high voltages. In addition, the compound represented by chemical formula 1 of the present invention is BF3 substituted at position 1. - It exhibits the characteristics of a Lewis acid and can trap anions present in the electrolyte. As a result, it can stabilize the anions in the electrolyte, which are Lewis bases, thereby suppressing the structural deformation of the negative electrode film, thereby improving the high-temperature storage characteristics of lithium secondary batteries. In addition, the reduction product in the electrolyte and the BF3 substituted at the 1st position of the compound represented by the chemical formula 1 - Since the interfacial adhesion at the negative electrode is strengthened by forming a BO bond, the strength of the film derived from the compound of chemical formula 1 is strengthened. As a result, the durability of the film is excellent even in lithium secondary batteries containing silicon-based negative electrode active materials that undergo extreme volume changes during charge and discharge, resulting in excellent life characteristics. Therefore, by suppressing the deterioration of the passivation ability of SEI at high temperatures, the deterioration of the negative electrode can be prevented, thereby improving the life characteristics of the battery. In the above chemical formula 1, R1 to R5 are each independently any one selected from the group consisting of H, F, a nitrile group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms, and preferably any one independently selected from the group consisting of H, F, a nitrile group, and an alkyl group having 1 to 5 carbon atoms. In the above chemical formula 1, n is any integer from 1 to 5, and preferably n can be any integer from 1 to 3. Preferably, the compound of the above chemical formula 1 may be a compound represented by the following chemical formula 1-1. [Chemical Formula 1-1] In the above chemical formula 1-1, n is any integer from 1 to 5, and preferably n can be any integer from 1 to 3. The additive for a non-aqueous electrolyte according to the present invention may be any one selected from the group consisting of the following chemical formulas 1-2a to 1-2f. [Chemical Formula 1-2a] [Chemical Formula 1-2b] [Chemical Formula 1-2c] [Chemical Formula 1-2d] [Chemical Formula 1-2e] [Chemical Formula 1-2f] The additive for a non-aqueous electrolyte according to the present invention may be included in an amount of 0.01 to 10 parts by weight, 0.1 to 5 parts by weight, 0.1 to 4 parts by weight, 0.3 to 2 parts by weight, or 0.5 to 1.0 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte. When the amount of the compound represented by the above chemical formula 1 satisfies the above range, the film-forming effect on the positive electrode is sufficient, so that the elution of the transition metal from the positive electrode active material is suppressed, and the viscosity of the electrolyte is maintained at an appropriate level, so that the rate characteristics and life characteristics are excellent when stored at high temperatures. The non-aqueous electrolyte according to the present invention may further include a lithium salt, an organic solvent, or other electrolyte additives. The above lithium salt is used as an electrolyte salt in a lithium secondary battery and is used as a medium for transferring ions. Typically, the lithium salt is used as a cation, for example, Li + , and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 -, PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - At least one selected from the group consisting of Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide; LiBETI), and LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide; LiTFSI). In addition to these, lithium salts commonly used in electrolytes of lithium secondary batteries can be used without limitation. The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film for preventing corrosion on the electrode surface, it may be included in the electrolyte at a concentration of 0.5 M to 2.0 M, preferably, at a concentration of 0.5 M to 1.8 M, and more preferably, at a concentration of 0.7 M to 1.6 M. When the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics during high-temperature storage of a lithium secondary battery is sufficient, and the viscosity of the non-aqueous electrolyte is appropriate, so that the electrolyte impregnation property can be improved. The above non-aqueous organic solvent may include at least one organic solvent 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 mixed organic solvent thereof. The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent with a high dielectric constant that can easily dissociate lithium salts in the electrolyte. As a specific example, the organic solvent may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, the organic solvent may include ethylene carbonate. In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and specifically, may include ethylmethyl carbonate (EMC). In addition, the organic solvent may further include at least one ester organic solvent selected from the group consisting of linear ester organic solvents and cyclic ester organic solvents in addition to at least one carbonate organic solvent selected from the group consisting of cyclic carbonate organic solvents and linear carbonate organic solvents in order to produce an electrolyte having high ionic conductivity. Specific examples of such linear ester organic solvents include at least one organic solvent 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 include at least one organic solvent 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 higher dielectric constant and lower surface tension than linear carbonate-based organic solvents, and is a solvent with less 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. In addition, the non-aqueous electrolyte of the present invention may additionally include a known electrolyte additive in the non-aqueous electrolyte as needed to prevent the non-aqueous electrolyte from decomposing in a high-power environment and causing cathode collapse, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and high-temperature battery expansion suppression effects. These other electrolyte additives may include at least one SEI film forming additive selected from the group consisting of representative examples of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds. The above cyclic carbonate compound may include vinylene carbonate (VC) or vinylethylene carbonate. The above halogen-substituted carbonate compound may include fluoroethylene carbonate (FEC). The above sultone compound may include at least one compound selected from the group consisting of 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone. The above sulfate compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS). The above phosphate compound may include at least one compound selected from the group consisting of lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, tris(2,2,2-trifluoroethyl)phosphate, and tris(2,2,2-trifluoroethyl)phosphite. The above borate compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalatoborate (LiB(C2O4)2, LiBOB). The above nitrile compound may include at least one compound selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile. The benzene compound may include fluorobenzene, the amine compound may include triethanolamine or ethylenediamine, and the silane compound may include tetravinylsilane. The above lithium salt compound is a compound different from the lithium salt included in the non-aqueous electrolyte, and may include lithium difluorophosphate (LiDFP), LiPO2F2, or LiBF4. Among these other electrolyte additives, when a combination of vinylene carbonate (VC), 1,3-propane sultone (PS), ethylene sulfate (Esa), and lithium difluorophosphate (LiDFP) is additionally included, a more robust SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, and gas generation that may be generated due to decomposition of the electrolyte at high temperatures can be suppressed, thereby improving the high-temperature stability of the secondary battery. Meanwhile, two or more of the above-described other electrolyte additives may be used in combination, and may be included in an amount of 0.01 to 30 wt%, specifically 0.1 to 25 wt%, and preferably 1 to 20 wt%, based on the total weight of the non-aqueous electrolyte. When the content of the above-described other electrolyte additives satisfies the above range, the effect of improving ionic conductivity and cycle characteristics is more excellent. lithium secondary battery The present invention also provides a lithium secondary battery comprising the non-aqueous electrolyte. Specifically, the lithium secondary battery includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte described above. At this time, the lithium secondary battery of the present invention can be manufactured according to a conventional method known in the art. For example, an electrode assembly can be formed by sequentially stacking a positive electrode, a negative electrode, and a separator between the positive and negative electrodes, then inserting the electrode assembly into a battery case and injecting the non-aqueous electrolyte according to the present invention. (1) Bipolar The above positive electrode can be manufactured by coating a positive electrode mixture slurry including a positive electrode active material, a binder, a conductive agent, and a solvent on a positive electrode current collector. The above-mentioned positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. The above-mentioned positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. More specifically, the lithium metal oxide may be a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (here, 0 <Y<1), LiMn 2-Z Ni Z O4 (where 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1O2 (here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2 (here, 0 <Y2<1), LiMn 2-Z1 Co Z1 O4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(wherein, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O4 (wherein, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O2 (wherein, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, such that 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc.), and one or more compounds of these may be included. Among these, the lithium metal oxides are LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni)) in that they can improve the capacity characteristics and stability of the battery. 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni) 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), and any one of these or a mixture of two or more of them may be used. Among these, a cathode active material having a nickel content of 80 atm% or more can be used because it can maximize the capacity characteristics of the battery. For example, the lithium transition metal oxide may include one represented by the following [Chemical Formula 2]. [Chemical Formula 2] Li x Ni a Co b M 1 c M 2 d O2 In the above chemical formula 2, the M 1 is at least one selected from Mn and Al, and may preferably be Mn or a combination of Mn and Al. M 2 It may be at least one selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S. The above x represents the atomic fraction of lithium in the lithium transition metal oxide, and may be 0.90≤x≤1.1, preferably 0.95≤x≤1.08, and more preferably 1.0≤x≤1.08. The above a represents the atomic fraction of nickel among the metal elements excluding lithium in the lithium transition metal oxide, and may be 0.80≤a<1.0, preferably 0.80≤a≤0.95, and more preferably 0.80≤a≤0.90. When the nickel content satisfies the above range, high-capacity characteristics can be realized. The above b represents the atomic fraction of cobalt among the metal elements excluding lithium in the lithium transition metal oxide, 0 <b<0.2, 0<b≤0.15, 또는 0.01≤b≤0.10일 수 있다. The above c is M among the metal elements excluding lithium in the lithium transition metal oxide. 1 It represents the atomic fraction of , 0 <c<0.2, 0<c≤0.15, 또는 0.01≤c≤0.10일 수 있다. The above d is M among the metal elements excluding lithium in the lithium transition metal oxide. 2 It represents the atomic fraction of , and can be 0≤d≤0.1, or 0≤d≤0.05. The above positive electrode active material may be included in an amount of 60 to 99 wt%, preferably 70 to 99 wt%, and more preferably 80 to 98 wt%, based on the total weight of solids excluding the solvent in the positive electrode mixture slurry. The above binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluoroelastomer, and various copolymers. Typically, the binder may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 1 to 10 wt%, based on the total weight of the solid content excluding the solvent in the positive electrode mixture slurry. The conductive agent is a component for further improving the conductivity of the positive electrode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the solid content in the positive electrode mixture slurry. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powders; conductive powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. Typically, the conductive agent may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 1 to 10 wt%, based on the total weight of solids excluding the solvent in the positive electrode mixture slurry. The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desirable viscosity when including the positive electrode active material, and optionally a binder and a conductive material. For example, the concentration of the solid content including the positive electrode active material, and optionally a binder and a conductive material may be 50 to 95 wt%, preferably 70 to 95 wt%, and more preferably 70 to 90 wt%. (2) Cathode The above negative electrode can be manufactured, for example, by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, or a graphite electrode made of carbon (C) or the metal itself can be used as the negative electrode. For example, when manufacturing a negative electrode by coating a negative electrode mixture slurry on the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 to 500 μm. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc. In addition, the negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide. As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used without particular limitation, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, etc. As the above metal or an alloy of these metals with lithium, a 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 and Sn or an alloy of these metals with lithium may be used. The above metal composite oxides include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1) and Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로 이루어진 군에서 선택되는 것이 사용될 수 있다. Materials capable of doping and dedoping the above lithium include Si, SiO x(0 <x≤2), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), Sn, SnO2, Sn-Y(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Y로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po 및 이들의 조합으로 이루어진 군에서 선택될 수 있다. Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide. The above negative active material may be included in an amount of 60 to 99 wt%, preferably 70 to 99 wt%, and more preferably 80 to 98 wt%, based on the total weight of the solid content in the negative electrode mixture slurry. The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof. Typically, the binder may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 1 to 10 wt%, based on the total weight of solids excluding the solvent in the negative electrode composite slurry. The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 1 to 20 wt% based on the total weight of the solid content in the negative electrode mixture slurry. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powders; conductive powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. The above-mentioned conductive agent may be included in an amount of 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 1 to 10 wt%, based on the total weight of solids excluding the solvent in the negative electrode mixture slurry. The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a desirable viscosity when including the negative electrode active material, and optionally a binder and a conductive material. For example, the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material may be 50 wt% to 95 wt%, preferably 70 wt% to 90 wt%. When using the metal itself as the above-mentioned cathode, it can be manufactured by physically bonding, rolling, or depositing the metal onto the metal thin film itself or the cathode current collector. The deposition method can use an electrical deposition method or a chemical vapor deposition method. For example, the metal to be bonded / rolled / deposited on the metal thin film itself or the negative electrode current collector may include one metal selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In), or an alloy of two metals. (3) Membrane In addition, as a 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 ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and 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. 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. Example Example 1 (Manufacture of non-aqueous electrolyte) LiPF6 was dissolved in an organic solvent (fluoroethylene carbonate (FEC): ethylmethyl carbonate (EMC): diethyl carbonate (DEC) = 10:45:45 volume ratio) to make a non-aqueous solvent at 1.3 M and vinylene carbonate (VC) at 0.5 wt%, and 0.1 g of the compound of the following chemical formula 1-1 was added to 99.9 g of the non-aqueous solvent to make a non-aqueous electrolyte. [Chemical Formula 1-2a] (Lithium secondary battery manufacturing) Cathode active material (LiNi) 0.85 Co 0.05 Mn 0.07 Al 0.03 O2): Conductive agent (carbon nanotube): Binder (polyvinylidene fluoride) was added to N-methyl-2-pyrrolidone (NMP), a solvent, in a weight ratio of 97.74:0.70:1.56 to prepare a positive electrode slurry (solid content 75.5 wt%). The positive electrode slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 15 ㎛, and dried and roll pressed to prepare a positive electrode. A negative electrode slurry (solid content 26 wt%) was prepared by adding a negative electrode active material (Si): conductive agent (carbon black): binder (styrene-butadiene rubber) in a weight ratio of 70.0:20.3:9.7 to a solvent, H2O. The negative electrode slurry was applied to one surface of a 15 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode. A polyethylene 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 secondary battery was manufactured in the same manner as in Example 1, except that 1.0 g of the compound of Chemical Formula 1-2b was added to 99.0 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. [Chemical Formula 1-2b] Example 3 A secondary battery was manufactured in the same manner as in Example 1, except that 2.0 g of a compound of the following chemical formula 1-2c was added to 98.0 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. [Chemical Formula 1-2c] Example 4 A secondary battery was manufactured in the same manner as in Example 1, except that 1.0 g of the compound of Chemical Formula 1-2a was added to 99.0 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. Example 5 A secondary battery was manufactured in the same manner as in Example 1, except that 3.0 g of the compound of Chemical Formula 1-2a was added to 97.0 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. Example 6 A secondary battery was manufactured in the same manner as in Example 1, except that 5.0 g of the compound of Chemical Formula 1-2a was added to 95.0 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. Comparative Example 1 A secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was manufactured using 100 g of the non-aqueous solvent manufactured in Example 1. Comparative Example 2 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of a compound of the following chemical formula A was added instead of the compound of the chemical formula 1-2a to 99.5 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte. [Chemical Formula A] Experimental Example 1 - Evaluation of High-Temperature Cycle Characteristics For each of the secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 and 2, cycle characteristics were evaluated. Specifically, each of the batteries manufactured in Examples 1 to 6 and Comparative Examples 1 and 2 was charged to 4.2 V at 0.33 C constant current at 45°C, then charged to 1 / 40 C at constant voltage, and discharged to 2.5 V at 0.33 C constant current, which constituted one cycle, and then 100 charge-discharge cycles were performed, and the resistance increase rate compared to the initial resistance after 100 cycles was measured. The results are shown in Table 1 below. Resistance Increase Rate (%) Example 150.4 Example 236.8 Example 354.9 Example 447.6 Example 548.5 Example 666.2 Comparative Example 194.6 Comparative Example 267.3 As shown in Table 1, Examples 1 to 6 using the non-aqueous electrolyte additive of the present invention had excellent life characteristics with a lower resistance increase rate compared to Comparative Example 1 that did not use it. In addition, Examples 1 to 6 using the non-aqueous electrolyte additive of the present invention had BF3 at position 1 of coumarin. - Compared to Comparative Example 2 using an additive of chemical formula A without a substituent containing , it was confirmed that the resistance increase rate was low and the life characteristics were excellent. Experimental Example 2 - Evaluation of High-Temperature Storage Characteristics For each of the secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 and 2, high-temperature storage characteristics were evaluated. Specifically, the secondary batteries of Examples 1 to 6 and Comparative Examples 1 and 2 were each fully charged to 4.2 V and then stored at 60°C for 4 weeks. Before preservation, the volume of the fully charged secondary battery was measured and set as the volume of the initial secondary battery. After 4 weeks, the volume of the preserved secondary batteries was measured again to calculate the volume increase during the 4-week storage period. The percentage ratio of the increased volume to the initial volume of the secondary batteries was calculated to derive the volume increase rate after 4 weeks. The results are shown in Table 2 below. Volume Increase Rate (%) Example 112.2 Example 29.6 Example 36.8 Example 410.4 Example 54.3 Example 63.1 Comparative Example 116.0 Comparative Example 224.8 As shown in Table 2 above, the secondary batteries of Examples 1 to 6 showed a smaller volume increase rate after 4 weeks and generated less gas at high temperatures compared to the secondary battery of Comparative Example 1 that did not use the additive. In addition, Examples 1 to 6 that used the non-aqueous electrolyte additive of the present invention had BF3 at position 1 of coumarin. -Compared to Comparative Example 2 using an additive of chemical formula A without a substituent containing , it was confirmed that the volume increase rate after 4 weeks was smaller and that less gas was generated at high temperatures.

Claims

1. Lithium salt; organic solvents; and A non-aqueous electrolyte comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 to R5 are each independently any one selected from the group consisting of H, F, a nitrile group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms. n is any integer from 1 to 5.

2. In claim 1, A non-aqueous electrolyte in which the compound of the above chemical formula 1 is a compound represented by the following chemical formula 1-1. [Chemical Formula 1-1] In the above chemical formula 1-1, n is any integer from 1 to 5.

3. In claim 1, The compound of the above chemical formula 1 is a non-aqueous electrolyte selected from the group consisting of compounds represented by the following chemical formulas 1-2a to 1-2f. [Chemical Formula 1-2a] [Chemical Formula 1-2b] [Chemical Formula 1-2c] [Chemical Formula 1-2d] [Chemical Formula 1-2e] [Chemical Formula 1-2f] 4. In claim 1, A non-aqueous electrolyte in which the compound of the above chemical formula 1 is contained in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the non-aqueous electrolyte.

5. In claim 1, A non-aqueous electrolyte wherein the lithium salt is included in a concentration of 0.5 M to 2.0 M.

6. In claim 1, The above lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 A non-aqueous electrolyte comprising at least one selected from the group consisting of LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2.

7. In claim 1, A non-aqueous electrolyte comprising at least one organic solvent 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.

8. In claim 1, A non-aqueous electrolyte further comprising at least one compound selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds as an additive.

9. Bipolar; cathode; and A lithium secondary battery comprising a non-aqueous electrolyte according to any one of claims 1 to 8.

10. In claim 9, A lithium secondary battery in which the positive electrode is a lithium nickel-based oxide represented by the following [chemical formula 2] as a positive electrode active material. [Chemical Formula 2] Li x Ni a Co b M 1 c M 2 d O2 In the above chemical formula 2, M 1 is Mn, Al or a combination thereof, and M 2 is at least one selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta and Nb, and 0.8≤x≤1.2, 0.8≤a<1, 0 <b<0.2, 0<c<0.2, 0≤d≤0.1임.

11. In claim 9, The above negative electrode is SiO as a negative electrode active material. x A lithium secondary battery comprising (0≤x<2).

Images