Non-aqueous electrolytes and lithium secondary batteries containing them

Abstract

The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a compound represented by a specific chemical formula. The non-aqueous electrolyte can form a stable film on the positive and negative electrodes, improving the long-term durability and lifespan performance of lithium secondary batteries.

Description

[Technical Field]

[0001] This invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the same. [Background technology]

[0002] In recent years, the application areas of lithium-ion batteries have rapidly expanded beyond power supply for electronic devices such as electrical, electronic, telecommunications, and computers to include power storage and supply for large-area devices such as automobiles and power storage devices. Consequently, there is an increasing demand for high-capacity, high-output, and highly stable secondary batteries.

[0003] The aforementioned lithium secondary battery typically consists of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte that acts as a medium for transferring lithium ions, and a separator. In this case, carbon-based active materials and silicon-based active materials can be used as the negative electrode active material. 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.

[0004] On the other hand, in recent years, lithium transition metal composite oxides with a nickel content of 80 mol% or more compared to transition metals have been studied in order to increase the energy density of the positive electrode. However, a problem with such high-nickel-content lithium transition metal composite oxides is that the high nickel content reduces the thermal stability of the positive electrode.

[0005] Alternatively, considering the problem of decreased thermal stability of the positive electrode when the nickel content is increased, the use of lithium transition metal composite oxides with an appropriately low nickel content has also been considered. However, when the nickel content is low, the driving voltage for the required energy density should be increased, but when driving at high voltages, problems such as electrolyte side reactions at the positive electrode, decreased high-temperature durability, and increased resistance may occur.

[0006] In order to achieve such a positive electrode and the high energy density of lithium secondary batteries containing it, problems such as thermal stability, high-temperature durability, and electrolyte side reactions must be resolved. [Overview of the project] [Problems that the invention aims to solve]

[0007] One objective of the present invention is to solve the above-mentioned problems and to provide a non-aqueous electrolyte that can improve the high-temperature durability of the positive and negative electrodes, prevent electrolyte side reactions, and in particular, improve long-term durability, high lifespan, and storage performance.

[0008] Another object of the present invention is to provide a lithium secondary battery containing the non-aqueous electrolyte. [Means for solving the problem]

[0009] [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a compound represented by the following chemical formula 1.

[0010] [Chemical formula 1] [ka]

[0011] In the above chemical formula 1, R1 is a substituent represented by the following chemical formula 2, L1 is a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms, and R2 is hydrogen or a substituent represented by the following chemical formula 3, R a , R b , and R c Each of these is independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN.

[0012] [Chemical formula 2] [ka]

[0013] In Chemical Formula 2, m is 1 or 2, and X1 and X2 are each independently -O- or -C(R 31 )(R 32 )-, and at least one of the X1 and X2 is -O-, and R 31 ~R 36 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, -C(=O)-R4, or -R5-O-C(=O)-R6, and the R4 and R6 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, the R5 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and the substituents of the L1, R4, R5, and R6 are each independently one or more selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3, * is a bonding site, and R 31 、R 32 、R 33 、R 34 、R 35 、and R 36 is located at one of them.

[0014] [Chemical Formula 3]

Chemical Structure

[0015] In Chemical Formula 3, * is a bonding site, and L2 is an alkylene group having 1 to 3 carbon atoms.

[0016] [2] The present invention provides the non-aqueous electrolyte according to [1], wherein the compound represented by Chemical Formula 1 contains at least one of the compounds represented by the following Chemical Formula 1-1 and the following Chemical Formula 1-2.

[0017] U [Chemical Formula 1-1]

Chemical Structure

[0018] [Chemical formula 1-2] [ka]

[0019] In the above chemical formulas 1-1 and 1-2, R a , R b , R c R1, L1, and L2 are defined as in Chemical Formula 1 above.

[0020] [3] The present invention provides a non-aqueous electrolyte according to either [1] or [2] above, wherein L1 is a methylene group.

[0021] [4] The present invention provides a non-aqueous electrolyte according to any one of [1] to [3] above, wherein the substituent represented by chemical formula 2 is one selected from substituents consisting of CS-1 to CS-15 below. [ka] [ka] [ka] [ka] [ka]

[0022] [5] The present invention provides a nonaqueous electrolyte according to any one of [1] to [4] above, wherein the substituent represented by chemical formula 2 is one selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11.

[0023] [6] The present invention provides a non-aqueous electrolyte according to any one of [1] to [5] above, wherein L2 is a methylene group.

[0024] [7] The present invention provides a non-aqueous electrolyte according to any one of [1] to [6] above, wherein the compound represented by chemical formula 1 comprises at least one of the compounds represented by the following chemical formulas 1-A and 1-B.

[0025] [Chemical formula 1-A] [ka]

[0026] [Chemical formula 1-B] [ka]

[0027] In the above chemical formulas 1-A and 1-B, R a , R b , and R c This is as defined in Chemical Formula 1 above.

[0028] [8] The present invention provides a non-aqueous electrolyte according to any one of [1] to [7] above, wherein the compound represented by chemical formula 1 comprises at least one of the compounds represented by the following chemical formulas 1-a and 1-b.

[0029] [Chemical formula 1-a] [ka]

[0030] [Chemical formula 1-b] [ka]

[0031] [9] The present invention provides a non-aqueous electrolyte according to any one of [1] to [8] above, wherein the additive further comprises a compound represented by the following chemical formula 4.

[0032] [Chemical formula 4] [ka]

[0033] In the above chemical formula 4, R a1 , R b1 , and R c1 Each of these is independently hydrogen, a C1-C3 alkyl group, or -CN, and L 21 This is an alkylene group having 1 to 3 carbon atoms.

[0034]

[10] The present invention provides a non-aqueous electrolyte according to any one of [1] to [9] above, wherein the additive further comprises a compound represented by the following chemical formula 5.

[0035] [Chemical formula 5] [ka]

[0036] In the aforementioned chemical formula 5, n is either 1 or 2. L 11 and L 12 Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms. R 11 and R 12 These are substituents, each independently represented by the following chemical formula 6: [Chemical formula 6] [ka] In the aforementioned chemical formula 6, m1 is either 1 or 2. X 11 and X 21 These are, independently, -O- or -C(R 311 )(R321 )-and the aforementioned X 11 and X 21 At least one of them is -O-, R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 These are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, and -C(=O)-R 41 , or -R 51 -OC(=O)-R 61 And, The aforementioned R 41 and R 61 Each of these is independently a substituted or unsubstituted C1-C6 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, or a substituted or unsubstituted C6-C20 aryl group. The aforementioned R 51 This is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms. Said L 11 , L 21 , R 41 , R 51 , and R 61 Each substituent is independently selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3. * indicates a binding site, R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 Located in one of the locations, L 11 and L 21 If both are directly joined, R 11 and R 21 This is not CS1-7 below, L 11 and L 21 When both are methylene groups and n is 2, R 11 and R 21 This is not CS1-2 as described below. [ka]

[0037]

[11] The present invention provides a non-aqueous electrolyte according to any one of [1] to

[10] above, wherein the substituent represented by chemical formula 6 is selected from the group consisting of CS1-1 to CS1-15 below. [ka] [ka]

[0038]

[12] The present invention provides a non-aqueous electrolyte according to any one of [1] to

[11] , wherein the compound represented by chemical formula 5 comprises at least one compound selected from the group consisting of compounds A to Q below. [ka] [ka] [ka] [ka] [ka] [ka]

[0039]

[13] The present invention provides a nonaqueous electrolyte according to any one of [1] to

[12] , wherein the compound represented by chemical formula 1 is contained in an amount of 0.01% to 10% by weight based on the total weight of the nonaqueous electrolyte.

[0040]

[14] The present invention relates to the lithium salt being LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 The present invention provides a non-aqueous electrolyte according to any one of [1] to

[13] , comprising at least one selected from the group consisting of LiBOB(LiB(C2O4)2), LiCF3SO3, LiFSI(LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI(LiN(SO2CF2CF3)2).

[0041]

[15] The present invention provides a lithium secondary battery comprising 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 according to any one of [1] to

[14] .

[0042]

[16] The present invention provides a lithium secondary battery according to

[15] , wherein the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a lithium transition metal oxide represented by the following chemical formula P-1.

[0043] [Chemical formula P-1] Li 1+x [Ni a Co b Mn c M 1 d ]O 2+w

[0044] In the aforementioned chemical formula P-1, 0≦x≦0.5, a+b+c+d=1, 0.5≦a≦0.7, 0≦b≦0.15, c=1-abd, 0≦d≦0.1, 0≦b / a≦0.2, 1≦a / c≦3, and 0≦w≦1. M 1 This is one or more elements 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. [Effects of the Invention]

[0045] The non-aqueous electrolyte of the present invention is characterized by containing, as an additive, a compound of a specific chemical formula having an imidazolium cation structure substituted with a cyclic sulfur oxide. When the compound is used as an additive, it can continuously contribute to the formation of coatings on the positive and negative electrodes even during long-term charging and discharging, resulting in significant improvements in long-term lifespan, high-temperature durability, and thermal stability.

[0046] Therefore, lithium secondary batteries containing the aforementioned non-aqueous electrolyte can have excellent lifespan and high-temperature storage characteristics. In particular, when applied to lithium secondary batteries requiring high energy density and high voltage drive, it can achieve significantly improved lifespan and high-temperature storage performance. [Modes for carrying out the invention]

[0047] First, before describing the present invention, the terms and words used in this specification and the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings. Rather, they should be interpreted in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0048] On the other hand, the terms used herein are used solely to describe exemplary embodiments and are not intended to limit the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0049] In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the presence of implemented features, figures, steps, components, or combinations thereof, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, components, or combinations thereof.

[0050] In this specification, "%" means weight percent unless explicitly indicated otherwise.

[0051] Before describing the present invention, in the description of "carbon number a to b" in the specification, "a" and "b" refer to the number of carbon atoms contained in a specific functional group. That is, the functional group may contain "a" to "b" carbon atoms.

[0052] Furthermore, in this specification, unless otherwise defined, "substitution" means that at least one hydrogen atom bonded to a carbon atom is substituted with an element other than hydrogen, for example, by an alkyl group having 1 to 5 carbon atoms or a fluorine element.

[0053] In this specification, the average particle size (D 50 The average particle size (D) can be defined as the particle size corresponding to 50% of the cumulative volume in the particle size distribution curve. 50 The particle size can be measured, for example, by laser diffraction. This laser diffraction method can generally measure particle sizes from the submicron region to several millimeters in size, and can yield highly reproducible and high-resolution results.

[0054] The present invention will be described in more detail below.

[0055] Non-aqueous electrolytes The present invention provides a non-aqueous electrolyte, specifically a non-aqueous electrolyte for lithium secondary batteries.

[0056] More specifically, the non-aqueous electrolyte according to the present invention comprises a lithium salt, an organic solvent, and an additive, wherein the additive contains a compound represented by the following chemical formula 1.

[0057] [Chemical formula 1] [ka]

[0058] In the above chemical formula 1, R1 is a substituent represented by the following chemical formula 2, L1 is a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms, and R2 is hydrogen or a substituent represented by the following chemical formula 3, R a , R b , and R c Each of these is independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN.

[0059] [Chemical formula 2] [ka]

[0060] In the above chemical formula 2, m is 1 or 2, and X1 and X2 are independently -O- or -C(R 31 )(R 32 )- and at least one of X1 and X2 is -O-, R 31 ~R 36 Each of the following is independently hydrogen, a C1-C6 alkyl group, -C(=O)-R4, or -R5-OC(=O)-R6, where R4 and R6 are independently substituted or unsubstituted C1-C6 alkyl groups, C2-C20 alkenyl groups, C2-C20 alkynyl groups, or substituted or unsubstituted C6-C20 aryl groups, where R5 is a substituted or unsubstituted C1-C6 alkylene group, where each of the substituents L1, R4, R5, and R6 is independently one or more selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3, where * is a bonding site, and R 31 , R 32 , R 33 , R 34 , R 35 , and R 36 It is located in one of the following locations.

[0061] [Chemical formula 3] [ka]

[0062] In the above Chemical Formula 3, * represents a bonding site, and L2 is an alkylene group having 1 to 3 carbon atoms.

[0063] The non-aqueous electrolyte of the present invention is characterized by containing, as an additive, a compound of a specific chemical formula having an imidazolium cation structure substituted with a cyclic sulfoxide. When the compound is used as an additive, it can continuously contribute to the formation of films on the positive and negative electrodes even during long-term charge and discharge, so the effects of improving long-term life performance, high-temperature durability, and thermal stability are remarkable. Therefore, a lithium secondary battery containing the above non-aqueous electrolyte can have excellent life performance and high-temperature storage characteristics. In particular, when applied to a lithium secondary battery that requires high energy density and high voltage driving, it is possible to achieve a remarkable improvement in life performance and high-temperature storage performance.

[0064] (1) Lithium salt First, the lithium salt will be described as follows.

[0065] In the non-aqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention, as the lithium salt, those commonly used in electrolytes for lithium secondary batteries can be used without limitation. For example, as the cation, Li + is included, and as the anion, 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 - (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CH3SO3 - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - , and (CF3CF2SO2)2N - At least one selected from the group consisting of the following is mentioned. Specifically, the lithium salts include LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, and LiB 10 Cl 10 The lithium salt may be at least one selected from the group consisting of LiBOB(LiB(C2O4)2), LiCF3SO3, LiTFSI(LiN(SO2CF3)2), LiFSI(LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI(LiN(SO2CF2CF3)2). Specifically, the lithium salt may consist of a single substance or a mixture of two or more substances 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), and more specifically, LiPF6.

[0066] The lithium salt may be modified as appropriate within the range of normal use, but in order to obtain the optimal effect of forming a corrosion-preventive film on the electrode surface, it may be included in the electrolyte at a concentration of 0.8 M to 3.0 M, specifically 1.0 M to 3.0 M. In this case, the unit "M" is molar concentration, and specifically may mean "mol / L".

[0067] When the concentration of the lithium salt satisfies the above range, the viscosity of the non-aqueous electrolyte can be controlled to achieve optimal impregnation, thereby improving the mobility of lithium ions and improving the capacity characteristics and cycle characteristics of the lithium secondary battery.

[0068] (2) Organic solvents The aforementioned organic solvent is not particularly limited as long as it is a non-aqueous solvent commonly used in lithium secondary batteries, and its decomposition due to oxidation reactions during the charging and discharging process of the secondary battery is minimized.

[0069] Specifically, the organic solvent may include at least one selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0070] Specifically, the organic solvent may include a cyclic carbonate organic solvent, a linear carbonate organic solvent, or a mixture thereof.

[0071] The cyclic carbonate-based organic solvent is a highly viscous organic solvent with a high dielectric constant that readily dissociates lithium salts in electrolytes. Specifically, it may contain 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. More specifically, it may contain at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC).

[0072] Furthermore, 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, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, and more specifically, may include at least one selected from the group consisting of ethyl methyl carbonate (EMC) and diethyl carbonate (DEC).

[0073] The organic solvent may be a mixture of a cyclic carbonate organic solvent and a linear carbonate organic solvent. In this case, the cyclic carbonate organic solvent and the linear carbonate organic solvent may be mixed in a volume ratio of 5:95 to 40:60, specifically in a volume ratio of 7:93 to 30:70. When the mixing ratio of the cyclic carbonate organic solvent and the linear carbonate organic solvent satisfies the above range, both high dielectric constant and low viscosity characteristics can be achieved, resulting in excellent ionic conductivity.

[0074] Furthermore, in order to produce an electrolyte having high ionic conductivity, the organic solvent may further contain at least one ester-based organic solvent selected from the group consisting of linear ester-based organic solvents and cyclic ester-based organic solvents, in addition to at least one carbonate-based organic solvent selected from the group consisting of cyclic carbonate-based organic solvents and linear carbonate-based organic solvents.

[0075] 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.

[0076] Furthermore, 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.

[0077] On the other hand, the organic solvent may be further used with any organic solvent commonly used for non-aqueous electrolytes, without limitation, as needed. For example, it may further contain at least one or more organic solvents from among ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents.

[0078] The ether-based solvent can be 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 of these, but is not limited to these.

[0079] The aforementioned glyme-based solvent is a solvent that has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents, and has low reactivity with metals, and may include, but is not limited to, at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0080] The nitrile solvent may be one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited to these.

[0081] (3) Additives The aforementioned additive contains a compound represented by the following chemical formula 1.

[0082] [Chemical formula 1] [ka]

[0083] In the above chemical formula 1, R1 is a substituent represented by the following chemical formula 2, L1 is a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms, and R2 is hydrogen or a substituent represented by the following chemical formula 3, R a , R b , and R c Each of these is independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN.

[0084] [Chemical formula 2] [ka]

[0085] In the above chemical formula 2, m is 1 or 2, and X1 and X2 are independently -O- or -C(R 31 )(R 32 )- and at least one of X1 and X2 is -O-, R 31 ~R 36 Each of the following is independently hydrogen, a C1-C6 alkyl group, -C(=O)-R4, or -R5-OC(=O)-R6, where R4 and R6 are independently substituted or unsubstituted C1-C6 alkyl groups, C2-C20 alkenyl groups, C2-C20 alkynyl groups, or substituted or unsubstituted C6-C20 aryl groups, where R5 is a substituted or unsubstituted C1-C6 alkylene group, where each of the substituents L1, R4, R5, and R6 is independently one or more selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3, where * is a bonding site, and R 31 , R32 , R 33 , R 34 , R 35 , and R 36 It is located in one of the following locations.

[0086] [Chemical formula 3] [ka]

[0087] In the above chemical formula 3, * represents a bonding site, and L2 is an alkylene group having 1 to 3 carbon atoms.

[0088] The compound represented by chemical formula 1 is characterized by containing, as an additive, a compound of a specific chemical formula having an imidazolium cation structure in which a cyclic sulfur oxide is substituted. The compound is a heterocompound having a cyclic structure in which carbon and nitrogen exist within the structure, and because electron-rich nitrogen elements are present in the structure, electrons can be uniformly distributed within the cyclic structure, the cyclic structure of the cyclic sulfur oxide can be maintained without immediate ring-opening during charging and discharging. The compound represented by chemical formula 1, having such characteristics, can continuously contribute to the formation of a film on the positive and negative electrodes during long-term charging and discharging. In particular, for positive electrodes with high energy density or those required to be driven at high voltages, a decrease in the thermal stability of the positive electrode and electrolyte side reactions at the positive electrode become problematic, which can result from a decrease in film durability or cracking of the film during long-term operation of the positive electrode. Since the compound represented by chemical formula 1 can continuously contribute to the formation of a film on the positive electrode during charging and discharging of lithium secondary batteries, it has a significant effect in improving long-term life performance, high-temperature durability, and thermal stability. Therefore, lithium secondary batteries containing the aforementioned non-aqueous electrolyte can have excellent life performance and high-temperature storage characteristics.

[0089] Furthermore, because the compound represented by chemical formula 1 has an imidazolium cation in its matrix structure, it suppresses the generation of Lewis acids such as HF and PF5. In addition, the nitrogen element acts as a Lewis base, removing Lewis acids generated in the electrolyte. This suppresses the deterioration behavior of the coating on the surface of the positive or negative electrode caused by Lewis acids, and prevents additional electrolyte decomposition. As a result, the self-discharge of lithium secondary batteries can be mitigated and the high-temperature storage characteristics can be improved.

[0090] In the above chemical formula 1, R1 is a substituent represented by the following chemical formula 2.

[0091] [Chemical formula 2] [ka]

[0092] In the above chemical formula 2, m may be 1 or 2. Specifically, m may be 2.

[0093] X1 and X2 are independently -O- or -C(R 31 )(R 32 )- and at least one of X1 and X2 is -O-. Specifically, X1 is -O- and / or X2 is -C(R 31 )(R 32 ) - That's fine.

[0094] R 31 ~R 36Each of these may independently be hydrogen, a C1-C6 alkyl group, -C(=O)-R4, or -R5-OC(=O)-R6. Each of R4 and R6 may independently be a substituted or unsubstituted C1-C6 alkyl group, specifically a substituted or unsubstituted C1-C3 alkyl group; a C2-C20 alkenyl group, specifically a C2-C5 alkenyl group; a C2-C20 alkynyl group, specifically a C2-C5 alkynyl group; or a substituted or unsubstituted C6-C20 aryl group, specifically a C6-C10 aryl group. R5 may be a substituted or unsubstituted C1-C6 alkylene group, specifically a substituted or unsubstituted C1-C3 alkylene group. If substituents exist on L1, R4, R5, and R6, each substituent on L1, R4, R5, and R6 may be independently one or more selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3. Specifically, R 31 ~R 36 It can be hydrogen.

[0095] In the above chemical formula 2, * is a bonding site, R 31 , R 32 , R 33 , R 34 , R 35 , and R 36 It may be located in one of the following positions. In this case, * is R 31 , R 32 , R 33 , R 34 , R 35 , or R 36 Located in R 31 , R 32 , R 33 , R 34 , R 35 , or R 36 In R, there is no hydrogen or other substituent present. 31 , R 32 , R 33 , R 34 , R 35 , or R 36 This could mean that L1 is directly bonded to an adjacent carbon atom.

[0096] The substituent represented by chemical formula 2 may be any one selected from the substituents CS-1 to CS-15 listed below. When the substituents CS-1 to CS-15 are applied to R1 of chemical formula 1, the overall structural stability of the compound is excellent, and it can smoothly perform its function as an additive. Specifically, the substituent represented by chemical formula 2 may be any one selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11, from the viewpoint of structural stability and ease of synthesis. More specifically, the substituent represented by chemical formula 2 may be CS-8. [ka] [ka] [ka] [ka] [ka]

[0097] In the above chemical formula 1, L1 may be a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms. More specifically, it may be a directly bonded, methylene group, or ethylene group. More specifically, it may be a methylene group because it facilitates the synthesis of the compound and suppresses decomposition of the compound after synthesis.

[0098] In the above chemical formula 1, R2 may be hydrogen or a substituent represented by the following chemical formula 3.

[0099] [Chemical formula 3] [ka]

[0100] The substituent represented by the chemical formula 3 contains a propargyl functional group that is easily reduced at the end, and by forming an electrode film with high passivation ability, it is possible to prevent an additional reduction decomposition reaction caused by the instability of the film, and improve the high-temperature durability of the electrode. In addition, the propargyl group contained in the substituent represented by the chemical formula 3 is adsorbed on the surface of the metallic impurities contained in the positive electrode, and the elution of the impurities can be suppressed. Therefore, the electrodeposition of metal ions on the surface of the negative electrode can be suppressed, and internal short circuit can also be prevented.

[0101] L2 may be an alkylene group having 1 to 3 carbon atoms, specifically a methylene group or an ethylene group, and more specifically a methylene group.

[0102] In the chemical formula 1, R a , R b , and R c may each independently be hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN. Specifically, each may independently be hydrogen or an alkyl group having 1 to 2 carbon atoms, and more specifically, each may be hydrogen.

[0103] Specifically, the compound represented by the chemical formula 1 may contain at least one of the compounds represented by the following chemical formula 1-1 and the following chemical formula 1-2. More specifically, the compound represented by the chemical formula 1 may contain the compound represented by the following chemical formula 1-1 and the compound represented by the following chemical formula 1-2.

[0104] [Chemical formula 1-1]

Chemical formula

[0105] [Chemical formula 1-2]

Chemical formula

[0106] In the chemical formula 1-1 and the chemical formula 1-2, Ra , R b , Rc, R1, L1, and L2 are as defined in Chemical Formula 1 above.

[0107] Specifically, the compound represented by Chemical Formula 1 may include at least one of the compounds represented by Chemical Formula 1-A and Chemical Formula 1-B below. More specifically, the compound represented by Chemical Formula 1 may include the compound represented by Chemical Formula 1-A and the compound represented by Chemical Formula 1-B below.

[0108] [Chemical Formula 1-A]

Chem.

[0109] [Chemical Formula 1-B]

Chem.

[0110] In Chemical Formulas 1-A and 1-B, R a , R b , and R c are as defined in Chemical Formula 1 above.

[0111] Specifically, the compound represented by Chemical Formula 1 may include at least one of the compounds represented by Chemical Formula 1-a and Chemical Formula 1-b below. More specifically, the compound represented by Chemical Formula 1 may include the compound represented by Chemical Formula 1-a and the compound represented by Chemical Formula 1-b below.

[0112] [Chemical Formula 1-a]

Chem.

[0113] [Chemical Formula 1-b]

Chem.

[0114] The compound represented by chemical formula 1 may be included in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, more specifically in an amount of 0.1% to 5% by weight, more specifically in an amount of 0.5% to 3% by weight, even more specifically in an amount of 0.2% to 1% by weight, and even more specifically in an amount of 0.5% to 1% by weight. When the amount is within the above range, it is preferable because the effect of improving the high-temperature durability of the secondary battery is achieved, and an increase in resistance due to the use of excessive additives can be prevented.

[0115] The additive may further include, along with the compound represented by chemical formula 1, at least one compound selected from the group consisting of the compound represented by the following chemical formula 4 and the compound represented by the following chemical formula 5. Specifically, the additive may further include, along with the compound represented by chemical formula 1, the compound represented by the following chemical formula 4 and the compound represented by the following chemical formula 5.

[0116] The aforementioned additive may further contain a compound represented by the following chemical formula 4.

[0117] [Chemical formula 4] [ka]

[0118] In the above chemical formula 4, R a1 , R b1 , and R c1 Each of these is independently hydrogen, a C1-C3 alkyl group, or -CN, and L 21 This is an alkylene group having 1 to 3 carbon atoms.

[0119] Furthermore, the compound represented by chemical formula 4 contains imidazole groups that suppress the generation of Lewis acids such as HF and PF5, and the nitrogen element acts as a Lewis base, removing Lewis acids generated in the electrolyte. As a result, the degradation behavior of the coating on the surface of the positive or negative electrode caused by Lewis acids can be suppressed, and additional electrolyte decomposition can be prevented. Consequently, the self-discharge of lithium secondary batteries can be mitigated and the high-temperature storage characteristics can be improved.

[0120] Furthermore, the compound represented by chemical formula 4 contains a readily reducible propagyl functional group at its terminal end, forming an electrode coating with high passivation capacity. This prevents additional reductive decomposition reactions caused by the instability of the coating, thereby improving the high-temperature durability of the electrode. Additionally, the propagyl group contained in the compound represented by chemical formula 4 is adsorbed onto the surface of metallic impurities contained in the positive electrode, suppressing the elution of impurities. This also prevents metal ions from electrodepositing onto the negative electrode surface, thus preventing internal short circuits.

[0121] In the above chemical formula 4, R a1 , R b1 , and R c1 Each of these is independently hydrogen, a C1-C3 alkyl group, or -CN, and more specifically, each may independently be hydrogen or a C1-C2 alkyl group, and more specifically, each may be hydrogen.

[0122] L 21 This may be an alkylene group having 1 to 3 carbon atoms, more specifically a methylene group or an ethylene group, and more specifically a methylene group.

[0123] Specifically, the compound represented by chemical formula 4 may include the compound represented by chemical formula 4-1 below.

[0124] [Chemical formula 4-1] [ka]

[0125] When the compound represented by chemical formula 4 is included in a non-aqueous electrolyte, the compound represented by chemical formula 4 may be included in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, specifically in an amount of 0.1% to 5% by weight.

[0126] The aforementioned additive may further contain a compound represented by the following chemical formula 5.

[0127] [Chemical formula 5] [ka]

[0128] In the aforementioned chemical formula 5, n is 1 or 2, and L 11 and L 12 Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms, and R 11 and R 12 These are substituents that are independently represented by the following chemical formula 6.

[0129] [Chemical formula 6] [ka]

[0130] In the aforementioned chemical formula 6, m1 is 1 or 2, and X 11 and X 21 These are, independently, -O- or -C(R 311 )(R 321 )-and the aforementioned X 11 and X 21 At least one of them is -O-, R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 These are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, and -C(=O)-R 41 , or -R 51 -OC(=O)-R 61And the R 41 and R 61 Each of these is independently a substituted or unsubstituted C1-C6 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, or a substituted or unsubstituted C6-C20 aryl group, and the R 51 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and the L 11 , L 21 , R 41 , R 51 , and R 61 Each substituent is independently selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3, where * is a binding site, and R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 Located in one of the L 11 and L 21 If both are directly joined, R 11 and R 21 This is not CS1-7 below, but L 11 and L 21 When both are methylene groups and n is 2, R 11 and R 21 This is not CS1-2 as described below. [ka]

[0131] The compound represented by chemical formula 5 is characterized by containing a sulfur oxide structure in the center and having a cyclic sulfur oxide structure at least one of its ends. By adopting such a chemical structure, stable anion formation can be induced when applied as a non-aqueous electrolyte additive, and furthermore, a stable SEI layer can be formed.

[0132] In the aforementioned chemical formula 5, n is either 1 or 2, and specifically may be 2.

[0133] L 11 and L 12 Each of these may independently be a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms, and more specifically, each may independently be a methylene group or an ethylene group, and more specifically, each may be a methylene group.

[0134] R 11 and R 12 These are, independently, substituents represented by the chemical formula 6.

[0135] In the aforementioned chemical formula 6, m1 may be 1 or 2, and more specifically, it may be 2.

[0136] X 11 and X 21 These are, independently, -O- or -C(R 311 )(R 321 )-and the aforementioned X 11 and X 21 At least one of them is -O-. Specifically, X 11 is -O-, or / and X 21 is -C(R 311 )(R 321 ) - That's fine.

[0137] R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 These are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, and -C(=O)-R 41 , or -R 51 -OC(=O)-R 61 It may be so. The above R 41 and R 61Each of these may independently be a substituted or unsubstituted C1-C6 alkyl group, specifically a substituted or unsubstituted C1-C3 alkyl group; a C2-C20 alkenyl group, specifically a C2-C5 alkenyl group; a C2-C20 alkynyl group, specifically a C2-C5 alkynyl group; or a substituted or unsubstituted C6-C20 aryl group, specifically a C6-C10 aryl group. 51 This may be a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, specifically a substituted or unsubstituted alkylene group having 1 to 3 carbon atoms. 11 , R 41 , R 51 , and R 61 If a substituent exists in L 11 , R 41 , R 51 , and R 61 Each substituent may be independently selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2, and -SO3. Specifically, R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 It can be hydrogen.

[0138] In the above chemical formula 6, * is a bonding site, R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 It may be located in one of the following positions. In this case, * is R 311 , R 321 , R 331 , R 341 , R 351 , or R 361 Located in R 311 , R 321 , R 331 , R 341 , R 351 , and R 361 In R, there is no hydrogen or other substituent present. 311 , R 321 , R331 , R 341 , R 351 , and R 361 adjacent carbon and L 11 or L 21 This could mean that they are directly joined together.

[0139] The substituent represented by chemical formula 6 may be any one selected from the substituents consisting of CS1-1 to CS1-15 below. 11 or R 12 When applied, the overall structural stability of the compound is excellent, and it can smoothly perform its function as an additive. Specifically, the substituent represented by chemical formula 6 may be any one selected from the group consisting of CS1-1, CS1-2, CS1-5, CS1-8, CS1-10, and CS1-11, from the viewpoint of structural stability and ease of synthesis. More specifically, the substituent represented by chemical formula 6 may be CS1-8. [ka] [ka]

[0140] More specifically, the compound represented by chemical formula 5 may include at least one compound selected from the group consisting of compounds A to Q below. More specifically, the compound represented by chemical formula 5 may include at least one compound selected from the group consisting of compounds A, F, and J below. More specifically, the compound represented by chemical formula 5 may include the compound represented by chemical formula A below. [ka] [ka] [ka] [ka] [ka] [ka]

[0141] When the compound represented by chemical formula 5 is included in a non-aqueous electrolyte, the compound represented by chemical formula 5 may be included in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, specifically in an amount of 0.1% to 5% by weight.

[0142] The method for producing the compound represented by chemical formula 1 is not particularly limited. For example, it can be produced by reacting an imidazole compound with a cyclic sulfur oxide compound that can react with the imidazole compound to bond a cyclic sulfur oxide functional group to the nitrogen position of the imidazole compound, thereby forming an imidazolium cation compound. For example, it can be produced by reacting the compound represented by chemical formula 4 with the compound represented by chemical formula 5 to form a compound in the form of an imidazolium cation substituted with a cyclic sulfur oxide. The compound represented by chemical formula 5 is a cyclic sulfur oxide (R 11 or R 12 Since -SO4-, --SO3-, etc., which can act as leaving groups, are bonded to the compound represented by chemical formula 4, the reaction of the imidazole group with the nitrogen in the compound represented by chemical formula 4 is easy. By adjusting the equivalent amounts during the reaction, all of the compounds represented by chemical formula 4 and the compound represented by compound 5 may form the compound represented by chemical formula 1, or some of these compounds may form the compound represented by chemical formula 1. On the other hand, when the compound represented by chemical formula 4 reacts with 1,3-propanesultone (PS), the lone pair of electrons of imidazole causes the ring of 1,3-propanesultone to open, making it difficult to realize the compound of chemical formula 1.

[0143] More specifically, the compound represented by chemical formula 1 can be produced or formed by the spontaneous reaction of the compounds represented by chemical formula 4 and chemical formula 5 after adding them to an organic solvent or non-aqueous electrolyte. Alternatively, the compound represented by chemical formula 1 can be produced or formed by adding the compounds represented by chemical formula 4 and chemical formula 5 to an organic solvent or non-aqueous electrolyte and allowing them to react by aging or standing at room temperature (15°C to 25°C) for a sufficient period of time.

[0144] The additive may further include additional additives along with the compound represented by chemical formula 1. These additional additives may be included in the non-aqueous electrolyte to prevent decomposition of the non-aqueous electrolyte and subsequent collapse of the negative electrode in high-power environments, or to provide low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and suppression of battery swelling at high temperatures.

[0145] Specifically, the aforementioned additional additives include lithium difluorophosphate (LiDFP), vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, and LiBOB (lithium difluoro(oxalato) borate). It may contain at least one selected from the group consisting of bis-(oxalato)borate, TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (Tris(trimethylsilyl)Phosphite), specifically lithium difluorophosphate (LiDFP).

[0146] The aforementioned additional additive may be included in the non-aqueous electrolyte in an amount of 0.1% to 15% by weight, more specifically, 0.3% to 10% by weight.

[0147] Lithium-ion rechargeable battery Furthermore, the present invention provides a lithium secondary battery. Specifically, the lithium secondary battery may contain the aforementioned non-aqueous electrolyte.

[0148] More specifically, the lithium secondary battery according to the present invention is characterized by comprising a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and the aforementioned non-aqueous electrolyte.

[0149] 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 the aforementioned non-aqueous electrolyte.

[0150] (1) Positive electrode The positive electrode may contain a positive electrode active material.

[0151] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium. Specifically, it may include a lithium transition metal composite oxide containing at least one transition metal selected from nickel, cobalt, manganese, and aluminum and lithium, preferably a lithium transition metal composite oxide containing a transition metal containing nickel, cobalt, and manganese and lithium.

[0152] For example, as the lithium transition metal composite oxide, there are lithium-manganese-based oxides (such as LiMnO2, LiMn2O4, etc.), lithium-cobalt-based oxides (such as LiCoO2, etc.), lithium-nickel-based oxides (such as LiNiO2, etc.), lithium-nickel-manganese-based oxides (such as LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt-based oxides (such as LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), lithium-manganese-cobalt-based oxides (such as LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt-based oxides (such as Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Coq1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are atomic fractions of independent elements, respectively, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.), and any one or two or more of these compounds may be included. Among them, from the point of being able to enhance the capacity characteristics and stability of the battery, the lithium transition metal composite oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel-manganese-cobalt oxide (e.g., 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, or Li(Ni 0.8 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 considering the remarkable improvement effect by controlling the types and content ratios of the constituent elements forming the lithium transition metal composite oxide, the lithium transition metal composite oxide is 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, or Li(Ni 0.8 Mn 0.1 Co0.1 ) may be O2, and one or more of these may be used as a mixture.

[0153] More specifically, the positive electrode active material may contain a lithium transition metal oxide represented by the following chemical formula P-1.

[0154] [Chemical formula P-1] Li 1+x [Ni a Co b Mn c M 1 d ]O 2+w

[0155] In the aforementioned chemical formula P-1, 0≦x≦0.5, a+b+c+d=1, 0.5≦a≦0.7, 0≦b≦0.15, c=1-abd, 0≦d≦0.1, 0≦b / a≦0.2, 1≦a / c≦3, 0≦w≦1, M 1 This is one or more elements 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.

[0156] The compound represented by the chemical formula P-1 has a lower nickel content compared to high-nickel lithium transition metal oxides, and therefore, in order to increase the energy density of the positive electrode, it needs to be driven at a high voltage (e.g., 4.35V or higher). However, when driven at such high voltages, side reactions of the positive electrode electrolyte become more severe, resulting in a significant decrease in lifespan and storage performance, reduced high-temperature durability, and a severe increase in resistance. This is due to the accelerated oxidative decomposition of organic solvents (such as ethylene carbonate) during high-voltage operation, which generates carbon dioxide (CO2), or due to Lewis acids such as HF and PF5 formed by the decomposition of lithium salts (such as LiPF6) decomposing the positive electrode coating, dissolving the transition metal of the positive electrode active material, and causing structural collapse. These problems can be resolved by using the aforementioned non-aqueous electrolyte. As described above, the aforementioned non-aqueous electrolyte can continuously provide a coating that can improve the durability of the positive electrode, and thus significantly prevents the problem of electrolyte side reactions that occur during long-term charging and discharging. Therefore, the lithium secondary battery according to the present invention can exhibit remarkably superior effects in long-term lifespan and high-temperature storage performance.

[0157] In the aforementioned chemical formula P-1, 0 ≤ x ≤ 0.5, specifically 0 ≤ x ≤ 0.2 may be used.

[0158] In the chemical formula P-1, 0.5 ≤ a ≤ 0.7, specifically 0.55 ≤ a ≤ 0.65 may be used.

[0159] In the chemical formula P-1, 0 ≤ b ≤ 0.15. b corresponds to the molar percentage of Co among the metals excluding lithium in the lithium transition metal oxide represented by the chemical formula A. According to the present invention, lowering the Co content offers cost advantages, and relatively increasing the proportion of Mn improves the structural stability of the positive electrode active material. Specifically, in the chemical formula P-1, 0 ≤ b ≤ 0.1 may be used.

[0160] In the chemical formula P-1, 0 ≤ b / a ≤ 0.2. If b / a exceeds 0.2, the proportion of Co in the transition metal is very high, which can increase the irreversibility within the structure. Specifically, in the chemical formula P-1, 0.05 ≤ b / a ≤ 0.2 may be the case.

[0161] In the aforementioned chemical formula P-1, c = 1 - abd, and 1 ≤ a / c ≤ 3. c corresponds to the molar percentage of Mn among the metals excluding lithium in the lithium transition metal oxide represented by the aforementioned chemical formula P-1. According to the present invention, the structural stability of the positive electrode active material can be improved by adjusting the molar ratio of Ni to Mn to 1 ≤ a / c ≤ 3. Specifically, it may be 1.5 ≤ a / c ≤ 2.5.

[0162] In the chemical formula P-1, M 1 d may be understood as the element to which the lithium transition metal oxide is doped, and specifically may be one or more 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 this case, d may be 0 ≤ d ≤ 0.1, specifically 0 ≤ d ≤ 0.05.

[0163] In other respects, the positive electrode active material may contain a lithium composite transition metal oxide represented by the following chemical formula P-2.

[0164] [Chemical formula P-2] Li 1+x1 (Ni a1 Co b1 Mn c1 M 2 d1 )O2

[0165] In the chemical formula P-2, M 2x1 is one or more elements 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, where 1+x1, a1, b1, c1, and d1 are the atomic fractions of independent elements, with 0≦x1≦0.2 and 0.50≦a1<1, 0 <b1≦0.25、0<c1≦0.25、0≦d1≦0.1、a1+b1+c1+d1=1である。

[0166] Preferably, a1, b1, c1, and d1 may be 0.70≦a1≦0.95, 0.025≦b1≦0.20, 0.025≦c1≦0.20, and 0≦d1≦0.05, respectively. Alternatively, a1, b1, c1, and d1 may be 0.80≦a1≦0.95, 0.025≦b1≦0.15, 0.025≦c1≦0.15, and 0≦d1≦0.05, respectively. Alternatively, a1, b1, c1, and d1 may be 0.85≦a1≦0.90, 0.05≦b1≦0.10, 0.05≦c1≦0.10, and 0≦d1≦0.03, respectively.

[0167] The positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector. In this case, the positive electrode active material may be included in the positive electrode active material layer.

[0168] The positive electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Specifically, the positive electrode current collector may contain at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy, preferably aluminum.

[0169] The thickness of the positive electrode current collector is typically between 3 μm and 500 μm.

[0170] The positive electrode current collector may have its surface textured to enhance the bonding force of the positive electrode active material. For example, the positive electrode current collector can be used in various forms such as film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0171] The positive electrode active material layer may be disposed on at least one side of the positive electrode current collector, specifically on one or both sides of the positive electrode current collector.

[0172] The positive electrode active material may be included in the positive electrode active material layer in an amount of 80% to 99% by weight, preferably 92% to 98.5% by weight, taking into consideration the sufficient capacity of the positive electrode active material.

[0173] The explanation of other positive electrode active materials has been given above and will be omitted here.

[0174] The positive electrode active material layer may further include a binder and / or a conductive material together with the positive electrode active material.

[0175] The binder is a component that assists in the binding of the active material to the conductive material and to the current collector, and specifically may contain at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-dientelpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride.

[0176] The binder may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, from the viewpoint of ensuring sufficient binding force between components such as the positive electrode active material.

[0177] The conductive material is used to assist and improve the conductivity of a secondary battery and is not particularly limited as long as it does not cause chemical changes and is conductive. Specifically, the positive electrode conductive material may contain 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, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably contains carbon nanotubes in order to improve conductivity.

[0178] The conductive material may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to ensure sufficient electrical conductivity.

[0179] The thickness of the positive electrode active material layer may be 30 μm to 400 μm, preferably 40 μm to 200 μm.

[0180] The positive electrode can be manufactured by coating a positive electrode slurry containing a positive electrode active material and selectively a binder, conductive material, and solvent for forming the positive electrode slurry onto the positive electrode current collector, followed by drying and rolling.

[0181] 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% to 90% by weight, specifically 50% to 80% by weight.

[0182] (2) Negative electrode The negative electrode faces the positive electrode.

[0183] The aforementioned negative electrode may contain a negative electrode active material.

[0184] The negative electrode active material is a material capable of reversibly intercalating / deintercalating lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, metalloid-based active materials, and lithium metal. Specifically, it may include at least one selected from carbon-based active materials and metalloid-based active materials.

[0185] The carbon-based active material may include at least one selected from the group consisting of graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably includes graphite. The graphite may be, for example, at least one of artificial graphite and natural graphite.

[0186] The average particle size (D) of the carbon-based active material 50 The thickness of the ) may be 10 μm to 30 μm, preferably 15 μm to 25 μm, in order to ensure structural stability during charging and discharging and to reduce side reactions with the electrolyte.

[0187] Specifically, the metalloid active material may include: at least one metalloid 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 metalloid 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 metalloid 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; and the like.

[0188] More specifically, the metalloid-based active material may include a silicon-based active material.

[0189] The silicon-based active material is SiOx The compound may contain compounds represented by (0 ≤ x < 2). SiO2 does not react with lithium ions and therefore cannot store lithium. For this reason, x is preferably within the above range, and more preferably the silicon-based active material is SiO2.

[0190] The average particle size (D) of the silicon-based active material 50 The thickness of the ) may be 1 μm to 30 μm, preferably 2 μm to 15 μm, in order to ensure structural stability during charging and discharging and to reduce side reactions with the electrolyte.

[0191] The negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. In this case, the negative electrode active material may be contained in the negative electrode active material layer.

[0192] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Specifically, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy.

[0193] The negative electrode current collector typically has a thickness of 3 μm to 500 μm.

[0194] The negative electrode current collector may have its surface textured to enhance the bonding force of the negative electrode active material. For example, the negative electrode current collector can be used in various forms such as film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0195] The negative electrode active material layer may be disposed on at least one side of the negative electrode current collector, specifically on one or both sides of the negative electrode current collector.

[0196] The negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight, preferably 75% to 95% by weight.

[0197] Further explanation regarding the positive electrode active material has been given above and will therefore be omitted.

[0198] The negative electrode active material layer may further include a binder and / or a conductive material together with the negative electrode active material.

[0199] The 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 contain, for example, at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and substances in which the hydrogen of these substances is substituted with Li, Na, or Ca, or may contain various copolymers thereof.

[0200] The binder may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0201] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive. Examples include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum 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.

[0202] The conductive material may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0203] The thickness of the negative electrode active material layer may be 10 μm to 200 μm, preferably 20 μm to 150 μm.

[0204] The negative electrode can be manufactured by coating at least one surface of a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and / or a solvent for forming the negative electrode slurry, followed by drying and rolling.

[0205] The solvent for forming the negative electrode slurry may include, for example, 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 the dispersion of the negative electrode active material, binder, and / or conductive material. The solid content of the negative electrode slurry may be 30% to 80% by weight, specifically 40% to 70% by weight.

[0206] (3) Separator The separator can be interposed between the positive electrode and the negative electrode.

[0207] Furthermore, the separator may be a conventional porous polymer film, such as a porous polymer film made from polyolefin polymers like ethylene monopolymer, propylene monopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, used alone or in a laminated configuration. Alternatively, a conventional porous nonwoven fabric, such as a nonwoven fabric made from high-melting-point glass fibers or polyethylene terephthalate fibers, may be used, but is not limited to these. In addition, a coated separator containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and may be used selectively as a single-layer or multi-layer structure.

[0208] The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch-shaped, or coin-shaped, using a can.

[0209] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the invention. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the described concept and technical idea, and it goes without saying that such variations and modifications fall within the scope of the appended claims.

[0210] Examples and Comparative Examples Example 1 (Manufacturing of non-aqueous electrolytes) As the organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80 was used.

[0211] A non-aqueous electrolyte was prepared by adding LiPF6 as a lithium salt, the compound represented by chemical formula 4-1, and compound A as additives to the aforementioned organic solvent.

[0212] The LiPF6 was included in the non-aqueous electrolyte at a molar concentration of 1.2 M. The compound represented by chemical formula 4-1 was included in the non-aqueous electrolyte at a content of 1% by weight. Compound A was included in the non-aqueous electrolyte at a content of 1% by weight.

[0213] The non-aqueous electrolyte was aged at room temperature for 72 hours, during which the compound represented by chemical formula 4-1 and compound A reacted with each other. The components in the non-aqueous electrolyte aged for 72 hours were 1 Analysis by H-NMR and LC-MS revealed that the compound represented by chemical formula 1-a and the compound represented by chemical formula 1-b were formed in the non-aqueous electrolyte at a concentration of 0.5% by weight, the compound represented by chemical formula 4-1 remained in the non-aqueous electrolyte at a concentration of 0.75% by weight, and compound A remained in the non-aqueous electrolyte at a concentration of 0.7% by weight.

[0214] (Manufacturing of lithium-ion batteries) Cathode active material (Li[Ni 0.6 Co 0.1 Mn 0.3 A positive electrode mixture slurry (solid content 75.5% by weight) was prepared by adding oxyoxyl (O2), a conductive material (carbon nanotube), and a binder (PVDF) in a weight ratio of 97.74:0.70:1.56 to the solvent N-methyl-2-pyrrolidone (NMP). The positive electrode mixture slurry was applied to one surface of a 12 μm thick positive electrode current collector (a thin Al film), and dried and roll-pressed to form a positive electrode active material layer (thickness: 136.6 μm), which was used as the positive electrode.

[0215] A negative electrode slurry (solid content 26% by weight) was prepared by adding a negative electrode active material (natural graphite), a conductive material (carbon black), and a binder (SBR-CMC) in a weight ratio of 96.15:1.55:2.30 to distilled water, which was used as a solvent. The negative electrode slurry was applied to one surface of a negative electrode current collector (Cu thin film) with a thickness of 8 μm, and the negative electrode was manufactured by drying and roll pressing.

[0216] In a dry room, a polyethylene porous film separator was interposed between the positive electrode and negative electrode manufactured as described above, and then the non-aqueous electrolyte manufactured as described above was injected to produce a secondary battery.

[0217] Example 2 A nonaqueous electrolyte and a lithium secondary battery were produced in the same manner as in Example 1, except that compound A was added to the nonaqueous electrolyte at a concentration of 5% by weight instead of 1% by weight.

[0218] After aging the non-aqueous electrolyte at room temperature for 72 hours, the compound represented by chemical formula 4-1 and compound A reacted with each other to form 0.5% by weight of the compound represented by chemical formula 1-a and the compound represented by chemical formula 1-b. 0.75% by weight of the compound represented by chemical formula 4-1 remained, and 4.75% by weight of compound A remained.

[0219] Example 3 A non-aqueous electrolyte and a lithium secondary battery were produced in the same manner as in Example 1, except that compound A was added to the non-aqueous electrolyte at a concentration of 0.5% by weight instead of 1% by weight.

[0220] After aging the non-aqueous electrolyte at room temperature for 72 hours, the compound represented by chemical formula 4-1 and compound A reacted with each other to form 0.2% by weight of the compound represented by chemical formula 1-a and the compound represented by chemical formula 1-b. 0.9% by weight of the compound represented by chemical formula 4-1 remained, and 0.4% by weight of compound A remained.

[0221] Example 4 A nonaqueous electrolyte and a lithium secondary battery were produced in the same manner as in Example 1, except that the compound represented by compound 4-1 was added to the nonaqueous electrolyte at a concentration of 5% by weight instead of 1% by weight.

[0222] After aging the non-aqueous electrolyte at room temperature for 72 hours, the compound represented by chemical formula 4-1 and compound A reacted with each other to form 0.5% by weight of the compound represented by chemical formula 1-a and the compound represented by chemical formula 1-b. 4.75% by weight of the compound represented by chemical formula 4-1 remained, and 0.75% by weight of compound A remained.

[0223] Example 5 A non-aqueous electrolyte and a lithium secondary battery were produced in the same manner as in Example 1, except that the compound represented by compound 4-1 was added to the non-aqueous electrolyte at a concentration of 0.5% by weight instead of 1% by weight.

[0224] After aging the non-aqueous electrolyte at room temperature for 72 hours, the compound represented by chemical formula 4-1 and compound A reacted with each other to form 0.2% by weight of the compound represented by chemical formula 1-a and the compound represented by chemical formula 1-b. 0.4% by weight of the compound represented by chemical formula 4-1 remained, and 0.9% by weight of compound A remained.

[0225] Comparative Example 1 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by chemical formula 4-1 and compound A were not added to the non-aqueous electrolyte.

[0226] Comparative Example 2 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the compound represented by chemical formula 4-1 was not added to the non-aqueous electrolyte.

[0227] Comparative Example 3 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that compound A was not added to the non-aqueous electrolyte.

[0228] Comparative Example 4 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 1% by weight of 1,3-propanesultone (PS) was added to the non-aqueous electrolyte instead of 1% by weight of compound A.

[0229] Experimental example Experimental Example 1: Evaluation of High-Temperature Cycle Performance The lithium secondary batteries of Examples 1-5 and Comparative Examples 1-4, manufactured as described above, were charged to 4.4V and 0.05C at 45°C under CC / CV and 0.33C conditions using an electrochemical charger / discharger. One cycle consisted of charging to 2.5V under CC and 0.33C conditions, and 200 charge / discharge cycles were performed.

[0230] (1) Capacity maintenance rate The capacity retention rate was calculated using the following formula, and the results are shown in Table 1 below.

[0231] Capacity retention rate (%) = {(Discharge capacity after 200 cycles / Discharge capacity after 1 cycle)} × 100

[0232] (2) Resistance increase rate After one charge-discharge cycle, the discharge capacity after one cycle was measured using an electrochemical charger. After adjusting the SOC to 50%, a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated from the difference between the voltage before and after pulse application.

[0233] After 200 charge-discharge cycles, the resistance after 200 cycles was calculated using the same method as described above, and the resistance increase rate was calculated using the following formula. The results are shown in Table 1 below.

[0234] Resistance increase rate (%) = (Resistance after 200 cycles - Initial resistance) / Initial resistance × 100

[0235] [Table 1]

[0236] Referring to Table 1, it can be confirmed that the lithium secondary batteries of Examples 1 to 5, which use a non-aqueous electrolyte containing the compound represented by chemical formula 1, exhibit superior high-temperature cycle performance compared to the comparative example.

[0237] Experimental Example 2: Evaluation of High-Temperature Storage Performance The lithium secondary batteries of Examples 1-5 and Comparative Examples 1-4, manufactured as described above, were charged to 4.4V and 0.05C at 25°C under CC / CV and 0.33C conditions, and then discharged to 2.5V under CC and 0.33C conditions to perform initial charge and discharge. Subsequently, they were charged to 4.4V and 0.05C at 25°C under CC / CV and 0.33C conditions, and then stored at 60°C for 8 weeks.

[0238] (1) Capacity maintenance rate After being stored for 8 weeks, the lithium secondary battery was charged to 4.4V and 0.05C at 25°C under CC / CV, 0.33C conditions, and then discharged to 2.5V under CC, 0.33C conditions, and the capacity during discharge was measured.

[0239] The capacity retention rate was evaluated using the following formula, and the results are shown in Table 2 below.

[0240] Capacity retention rate (%) = (Discharge capacity after 8 weeks of storage / Initial discharge capacity) × 100

[0241] (2) Resistance increase rate After the initial charge and discharge described above, the capacity was confirmed at room temperature. Based on the discharge capacity, the battery was charged to 50% of its state of charge (SOC), discharged at a current of 2.5C for 10 seconds, and the resistance was measured from the voltage drop difference to determine the initial resistance. After storage at 60°C for 8 weeks, the resistance was measured again using the same method to determine the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 2 below.

[0242] Resistance increase rate (%) = (Final resistance - Initial resistance) / (Initial resistance) × 100

[0243] [Table 2]

[0244] Referring to Table 2, it can be confirmed that the lithium secondary batteries of Examples 1 to 5, which use a non-aqueous electrolyte containing the compound represented by chemical formula 1, exhibit superior high-temperature storage performance compared to the comparative example.

Claims

1. Lithium salts and Organic solvents and It contains additives, A non-aqueous electrolyte comprising the additive a compound represented by the following chemical formula 1. [Chemical formula 1] 【Chemistry 1】 (In the above chemical formula 1, R １ This is a substituent represented by the following chemical formula 2, L １ These are directly bonded, substituted, or unsubstituted alkylene groups having 1 to 6 carbon atoms. R ２ is hydrogen or a substituent represented by the following chemical formula 3, R ａ , R ｂ , and R ｃ Each of these is independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN. [Chemical formula 2] 【Chemistry 2】 In the above chemical formula 2, m is 1 or 2. X １ and X ２ each independently represents -O- or -C(R ３１ )(R ３２ )-, and at least one of said X １ and X ２ is -O- R ３１ ~R ３６ These are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, and -C(=O)-R. ４ , or -R ５ -OC(=O)-R ６ And, The aforementioned R ４ and R ６ Each of these is independently a substituted or unsubstituted C1-C6 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, or a substituted or unsubstituted C6-C20 aryl group. The aforementioned R ５ This is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms. Said L １ , R ４ , R ５ , and R ６ The substituents are, independently, deuterium, -F, -Cl, -Br, -I, -CN, and -NO. ２ , and -SO ３ One or more selected from the group consisting of, * indicates a binding site, R ３１ , R ３２ , R ３３ , R ３４ , R ３５ , and R ３６ Located in one of the locations, [Chemical formula 3] 【Transformation 3】 In the aforementioned chemical formula 3, * indicates a binding site. L ２ (This refers to an alkylene group having 1 to 3 carbon atoms.)

2. The non-aqueous electrolyte according to claim 1, wherein the compound represented by chemical formula 1 comprises at least one of the compounds represented by the following chemical formulas 1-1 and 1-2. [Chemical formula 1-1] 【Chemistry 4】 [Chemical formula 1-2] 【Transformation 5】 (In the above chemical formulas 1-1 and 1-2, R ａ , R ｂ , R ｃ , R １ , L １ , and L ２ (This is as defined in Chemical Formula 1 above.)

3. L １ The non-aqueous electrolyte according to claim 1, wherein is a methylene group.

4. The non-aqueous electrolyte according to claim 1, wherein the substituent represented by chemical formula 2 is one selected from substituents consisting of CS-1 to CS-15 below. 【Transformation 6】 【Transformation 7】 【Transformation 8】 【Chemistry 9】 【Chemistry 10】

5. The non-aqueous electrolyte according to claim 1, wherein the substituent represented by chemical formula 2 is one selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11.

6. L ２ The non-aqueous electrolyte according to claim 1, wherein is a methylene group.

7. The non-aqueous electrolyte according to claim 1, wherein the compound represented by chemical formula 1 comprises at least one of the compounds represented by the following chemical formulas 1-A and 1-B. [Chemical formula 1-A] 【Chemistry 11】 [Chemical formula 1-B] 【Chemistry 12】 (In the above chemical formulas 1-A and 1-B, R ａ , R ｂ , and R ｃ (This is as defined in Chemical Formula 1 above.)

8. The non-aqueous electrolyte according to claim 1, wherein the compound represented by chemical formula 1 comprises at least one of the compounds represented by the following chemical formulas 1-a and 1-b. [Chemical formula 1-a] 【Chemistry 13】 [Chemical formula 1-b] 【Chemistry 14】

9. The non-aqueous electrolyte according to claim 1, wherein the additive further comprises a compound represented by the following chemical formula 4. [Chemical formula 4] 【Chemistry 15】 (In the above chemical formula 4, R ａ１ , R ｂ１ , and R ｃ１ Each of these is independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN. L ２１ (This refers to an alkylene group having 1 to 3 carbon atoms.)

10. The non-aqueous electrolyte according to claim 1, wherein the additive further comprises a compound represented by the following chemical formula 5. [Chemical formula 5] 【Chemistry 16】 (In the above chemical formula 5, n is either 1 or 2, L １１ and L １２ Each of these is independently a directly bonded, substituted, or unsubstituted alkylene group having 1 to 6 carbon atoms. R １１ and R １２ These are substituents that are independently represented by the following chemical formula 6, [Chemical formula 6] 【Chemistry 17】 In the aforementioned chemical formula 6, m1 is either 1 or 2. X １１ and X ２１ These are, independently, -O- or -C(R ３１１ ) (Caution ３２１ ) - and the aforementioned X １１ and X ２１ At least one of them is -O-, R ３１１ , R ３２１ , R ３３１ , R ３４１ , R ３５１ , and R ３６１ These are, independently, hydrogen, an alkyl group having 1 to 6 carbon atoms, and -C(=O)-R. ４１ , or -R ５１ -OC(=O)-R ６１ And, The aforementioned R ４１ and R ６１ Each of these is independently a substituted or unsubstituted C1-C6 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, or a substituted or unsubstituted C6-C20 aryl group. The aforementioned R ５１ This is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms. Said L １１ , L ２１ , R ４１ , R ５１ , and R ６１ The substituents are, independently, deuterium, -F, -Cl, -Br, -I, -CN, and -NO. ２ , and -SO ３ One or more selected from the group consisting of, * indicates a binding site, R ３１１ , R ３２１ , R ３３１ , R ３４１ , R ３５１ , and R ３６１ Located in one of the locations, L １１ and L ２１ If both are direct bonds, R １１ and R ２１ This is not CS1-7 below, L １１ and L ２１ are both methylene groups, and when n is 2, R １１ and R ２１ are not simultaneously the following CS1-2. [Chemistry 18]

11. The non-aqueous electrolyte according to claim 10, wherein the substituent represented by the chemical formula 6 is selected from the group consisting of CS1-1 to CS1-15 below. 【Chemistry 19】 【Chemistry 20】

12. The non-aqueous electrolyte according to claim 11, wherein the compound represented by chemical formula 5 comprises at least one compound selected from the group consisting of compounds A to Q below. 【Chemistry 21】 【Chemistry 22】 【Chemistry 23】 【Chemistry 24】

13. The nonaqueous electrolyte according to claim 1, wherein the compound represented by chemical formula 1 is contained in an amount of 0.01% to 10% by weight based on the total weight of the nonaqueous electrolyte.

14. The lithium salt is selected from at least one of the group consisting of LiCl, LiBr, LiI, LiBF ４ , LiClO ４ , LiAlO ４ , LiAlCl ４ , LiPF ６ , LiSbF ６ , LiAsF ６ , LiB １０ Cl １０ , LiBOB (LiB(C ２ O ４ ) ２ , LiCF ３ SO ３ , LiFSI (LiN(SO ２ F) ２ ), LiCH ３ SO ３ , LiCF ３ CO ２ , LiCH ３ CO ２ , and LiBETI (LiN(SO ２ CF ２ CF ３ ) ２ ), and the non-aqueous electrolyte according to claim 1 contains at least one selected from the group consisting of

15. Positive electrode and, A negative electrode opposite the positive electrode, A separator interposed between the positive electrode and the negative electrode, A lithium secondary battery comprising the non-aqueous electrolyte described in claim 1.

16. The positive electrode includes a positive electrode active material. The lithium secondary battery according to claim 15, wherein the positive electrode active material comprises a lithium transition metal oxide represented by the following chemical formula P-1. [Chemical formula P-1] Li １＋ｘ [Ni ａ Co ｂ Mn ｃ M １ ｄ ]O ２＋ｗ (In the above chemical formula P-1, 0≦x≦0.5, a+b+c+d=1, 0.5≦a≦0.7, 0≦b≦0.15, c=1-a-b-d, 0≦d≦0.1, 0≦b / a≦0.2, 1≦a / c≦3, 0≦w≦1, M １ (This is one or more 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.)

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