Title of invention: Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery containing the same Technical field [One] Cross-reference with related application(s) [2] This application claims the benefit of priority based on Korean Patent Application No. 2017-0150920 filed on November 13, 2017 and Korean Patent Application No. 2018-0138408 filed on November 12, 2018, and all disclosed in the documents of the corresponding Korean patent application. The content is incorporated as part of this specification. [3] [4] Technical field [5] The present invention relates to a non-aqueous electrolyte for a lithium secondary battery and a lithium secondary battery including the same. Background [6] In recent years, interest in energy storage technology is increasing, and as the fields of application to mobile phones, camcorders, notebook PCs, and even electric vehicles are expanded, efforts for research and development of electrochemical devices are gradually becoming concrete. [7] Among electrochemical devices, interest in the development of secondary batteries capable of charging and discharging is emerging. In particular, lithium secondary batteries developed in the early 1990s are attracting attention for the advantages of high operating voltage and remarkably large energy density. [8] The currently applied lithium secondary battery is composed of a carbon-based negative electrode capable of storing and releasing lithium ions, a positive electrode made of a lithium-containing transition metal oxide, and a non-aqueous electrolyte in which an appropriate amount of lithium salt is dissolved in a carbonate-based organic solvent. [9] In the lithium secondary battery, lithium ions from the positive electrode are inserted into the negative electrode, for example, carbon particles by charging, and energy is transferred while repeating the phenomenon of being desorbed again during discharge, thereby enabling charging and discharging. [10] The lithium secondary battery forms a film on the negative electrode surface as some of the electrolyte additive components and organic solvents decompose in the 0.5V~3.5V range during initial charging, and lithium ions generated from the positive electrode move to the negative electrode, By reacting with the electrolyte, compounds such as Li 2 CO 3 , Li 2 O and LiOH are produced. These compounds form a kind of passivation layer on the surface of the negative electrode, which is called a solid electrolyte interface (SEI) film. [11] The SEI film formed during initial charging prevents the reaction between lithium ions and carbon-based negative electrodes or other materials during charging and discharging. It also acts as an ion tunnel, allowing only lithium ions to pass. This ion tunnel serves to prevent the collapse of the structure of the carbon-based negative electrode by solvating lithium ions and the organic solvents of a high molecular weight electrolyte that move together with the carbon-based negative electrode. Therefore, in order to improve the high-temperature cycle characteristics and low-temperature output of the lithium secondary battery, a solid SEI film must be formed on the negative electrode of the lithium secondary battery. [12] On the other hand, when the organic solvent used in the non-aqueous electrolyte of a lithium secondary battery is generally stored at a high temperature for a long time, it is oxidized by a side reaction with the transition metal oxide emitted from the positive electrode to generate gas, and the battery swells and Deformation of the electrode assembly occurs. [13] In particular, when stored at high temperature in a fully charged state (for example, after charging 100% at 4.2V and storing at 60°C), the SEI film gradually collapses and the cathode is exposed, and the exposed cathode reacts with the electrolyte to continuously cause side reactions. Therefore, gases such as CO, CO 2 , CH 4 and C 2 H 6 are generated. This, in turn, increases the internal pressure of the battery, causing deformation such as swelling of the battery. In addition, if an internal short circuit of the battery is caused by such battery deformation, battery deterioration may appear, and the battery may ignite or explode. [14] In order to solve this problem recently, a method including an additive capable of forming an SEI film in a non-aqueous electrolyte has been proposed. However, while other side effects occur due to the electrolyte additive, there is another problem that the overall performance of the secondary battery is reduced. [15] Accordingly, there is a continuous need to develop a new non-aqueous electrolyte solution capable of improving high temperature and overcharge stability of a lithium secondary battery while minimizing side effects. [16] [17] Prior art literature [18] Japanese Laid-Open Patent Publication No. 2017-117684 Detailed description of the invention Technical challenge [19] The present invention is to provide a non-aqueous electrolyte for a lithium secondary battery comprising an additive capable of forming a stable film on the electrode surface. [20] In addition, the present invention is to provide a lithium secondary battery having improved high-temperature and overcharge stability and low-temperature output characteristics by including the non-aqueous electrolyte for a lithium secondary battery. Means of solving the task [21] In order to achieve the above object, in one embodiment of the present invention [22] Lithium salt; Organic solvent; And an additive, [23] The additive includes lithium difluorophosphate (LiPO 2 F 2 ): LiDFP, fluorobenzene (FB), tetravinyl silane (TVS), and one sulfonate group or sulfate group. It provides a non-aqueous electrolyte for a lithium secondary battery, which is a mixed additive containing the compound in a weight ratio of 1: 2 to 8: 0.05 to 0.3: 0.5 to 2. [24] Specifically, the weight ratio of the lithium difluorophosphate, fluorobenzene, tetravinylsilane, and the compound containing one sulfonate group or sulfate group may be 1: 2 to 6: 0.05 to 0.3: 0.5 to 1.5. [25] Compounds containing one sulfonate group or sulfate group include ethylene sulfate, trimethylene sulfate, methyl trimethylene sulfate, 1,3-propane sultone, 1 ,4-butane sultone, ethene sultone, 1,4-butene sultone, 1-methyl-1,3-propene sultone and at least selected from the group consisting of 1,3-Propene sultone It may be one or more, and specifically, may be at least one or more selected from the group consisting of ethylene sulfate, trimethylene sulfate, 1,3-propane sultone, and 1,3-propene sultone. [26] In the nonaqueous electrolyte for a lithium secondary battery of the present invention, the additive may be included in an amount of 1% to 18% by weight based on the total weight of the nonaqueous electrolyte for a lithium secondary battery. [27] On the other hand, the non-aqueous electrolyte for a lithium secondary battery of the present invention is for forming at least one SEI film selected from the group consisting of a halogen-substituted carbonate compound, a nitrile compound, a cyclic carbonate compound, a phosphate compound, a borate compound, and a lithium salt compound. It may further include a first additive. [28] In addition, the non-aqueous electrolyte for a lithium secondary battery of the present invention comprises at least one second additive for forming an SEI film selected from the group consisting of diphenyl disulfide, di-p-tolyl disulfide, and bis(4-methoxyphenyl) disulfide (BMPDS). It may contain additionally. [29] [30] In addition, in an embodiment of the present invention [31] In a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and a non-aqueous electrolyte, [32] The non-aqueous electrolyte provides a lithium secondary battery including the non-aqueous electrolyte for a lithium secondary battery of the present invention. [33] At this time, the positive electrode includes a lithium-nickel-manganese-cobalt-based oxide as a positive electrode active material, and specifically, the lithium-nickel-manganese-cobalt-based oxide is Li (Ni 1/3 Mn 1/3 Co 1/3 ) O 2 , Li(Ni 0.35 Mn 0.28 Co 0.37 )O 2 , Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2,And Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 It may be at least one selected from the group consisting of. Effects of the Invention [34] According to the present invention, a non-aqueous electrolyte solution for a lithium secondary battery capable of forming a stable SEI film on the surface of a negative electrode can be prepared by including an additive obtained by mixing four types of compounds in a specific ratio. In addition, by including this, it is possible to manufacture a lithium secondary battery having improved overall performance such as high temperature and overcharge stability and low temperature output characteristics. Brief description of the drawing [35] The following drawings attached to the present specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of ​​the present invention together with the content of the present invention, so the present invention is limited to the matters described in such drawings. It is limited and should not be interpreted. [36] 1 is a graph showing a result of evaluation of low-temperature output characteristics of a lithium secondary battery according to Experimental Example 1 of the present invention. [37] 2 is a graph showing the results of evaluating overcharge stability of the lithium secondary battery of Example 1 according to Experimental Example 6 of the present invention. [38] 3 is a graph showing the results of evaluation of overcharge stability of the lithium secondary battery of Comparative Example 7 according to Experimental Example 6 of the present invention. Best mode for carrying out the invention [39] Hereinafter, the present invention will be described in more detail. [40] The terms or words used in the specification and claims should not be construed as being limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to describe his own invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of ​​the present invention based on the principle that there is. [41] In addition, terms used in the present specification are only used to describe exemplary embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. [42] In the present specification, terms such as "comprise", "include", or "have" are intended to designate the presence of implemented features, numbers, steps, elements, or a combination thereof, and one or more other features or It is to be understood that the possibility of the presence or addition of numbers, steps, components, or combinations thereof is not preliminarily excluded. [43] [44] Non-aqueous electrolyte for lithium secondary batteries [45] Specifically, in one embodiment of the present invention [46] Lithium salt; Organic solvent; And an additive, [47] The additive is a compound containing lithium difluorophosphate (LiDFP), fluorobenzene (FB), tetravinylsilane (TVS), and one sulfonate group or a sulfate group 1:1. To 8: 0.05 to 0.3: to provide a non-aqueous electrolyte for a lithium secondary battery, which is a mixed additive containing in a weight ratio of 0.5 to 2. [48] [49] (1) lithium salt [50] In the non-aqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention, the lithium salt may be used without limitation, those commonly used in the electrolyte for a lithium secondary battery, for example, Li + as a cation of the lithium salt , anion is F - , Cl - , Br - , I - , NO 3 - , N (CN) 2 - , ClO 4 - , BF 4 - , B 10 Cl 10 - , PF 6 - , CF 3 SO 3 - , CH 3 CO 2 - , CF 3 CO 2 - , AsF 6 - , SbF 6 - , AlCl 4 - , AlO 4 - , CH 3 SO 3 - , BF 2 C 2 O 4 - , BC 4 O 8 - , PF 4 C 2 O 4 - , PF 2 C 4 O 8 - , (CF 3 ) 2 PF 4 - , (CF 3 ) 3 PF 3 - , (CF 3 ) 4 PF 2 - , (CF 3 ) 5 PF - , C 4 F 9 SO 3 - , CF 3 CF 2 SO 3 - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 the SO 3 - , SCN - and (CF 3CF 2 SO 2 ) 2 N -It may be at least any one selected from the group consisting of. [51] Specifically, the lithium salt is LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , LiAlO 4 , LiCH 3 SO 3 , LiFSI (lithium fluorosulfonyl imide, LiN(SO 2 F) 2), LiTFSI (lithium (bis)trifluoromethanesulfonimide, LiN(SO 2 CF 3 ) 2 ) and LiBETI (lithium bisperfluoroethanesulfonimide, LiN(SO 2 C 2 F 5 ) 2 ) A single substance or a mixture of two or more selected from the group consisting of I can. [52] Specifically, the lithium salt is a single substance or two or more selected from the group consisting of LiPF 6 , LiBF 4 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiCH 3 SO 3 , LiFSI, LiTFSI and LiN(C 2 F 5 SO 2 ) 2 It may contain mixtures. However, the lithium salt does not include LiDFP, which is a lithium salt included in the mixed additive. [53] The lithium salt may be appropriately changed within a range that is generally usable, but may be specifically contained in an electrolyte solution in an amount of 0.1M to 3M, specifically 0.8M to 2.5M. If the concentration of the lithium salt exceeds 3M, the viscosity of the non-aqueous electrolyte increases, thereby reducing the lithium ion migration effect, and reducing the wettability of the non-aqueous electrolyte, making it difficult to form a uniform SEI film. [54] [55] (2) organic solvent [56] In addition, in the non-aqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention, the organic solvent can minimize decomposition due to oxidation reactions in the charging and discharging process of the secondary battery, and exhibit desired properties together with additives. If it is, there is no limit to its kind. For example, a carbonate-based organic solvent, an ether-based organic solvent, or an ester-based organic solvent may be used alone or in combination of two or more. [57] Among the organic solvents, the carbonate-based organic solvent may include at least one of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. Specifically, the cyclic carbonate-based organic solvent is ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene Carbonate, 2,3-pentylene carbonate, vinylene carbonate, and fluoroethylene carbonate (FEC). As such, it may include a mixed solvent of propylene carbonate having a low melting point. [58] In addition, the linear carbonate-based organic solvent is a solvent having a low viscosity and a low dielectric constant, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methyl It may include at least one or more selected from the group consisting of propyl carbonate and ethylpropyl carbonate, and more specifically, dimethyl carbonate. [59] The ether-based organic solvent may be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methylpropyl ether, and ethylpropyl ether, or a mixture of two or more of them, but is limited thereto. It does not become. [60] The ester-based organic solvent may be at least one selected from the group consisting of a linear ester-based organic solvent and a cyclic ester-based organic solvent. [61] At this time, the linear ester-based organic solvent is any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate as specific examples thereof, or A mixture of two or more of these may be typically used, but is not limited thereto. [62] Specific examples of the cyclic ester-based organic solvent are any one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone, or 2 of them. A mixture of more than one species may be used, but is not limited thereto. [63] The organic solvent may be a high-viscosity cyclic carbonate-based organic solvent that easily dissociates lithium salts in the electrolyte due to its high dielectric constant. In addition, in order to prepare an electrolyte having a higher electrical conductivity, the organic solvent includes a low viscosity, low dielectric constant linear carbonate compound and a linear ester compound such as dimethyl carbonate and diethyl carbonate together with the environmental carbonate organic solvent. It can be mixed and used in an appropriate proportion. [64] More specifically, the organic solvent may be used by mixing a cyclic carbonate-based compound and a linear carbonate-based compound, and the weight ratio of the cyclic carbonate-based compound: the linear carbonate-based compound among the organic solvents may be 10:90 to 70:30. [65] [66] (3) mixed additives [67] Meanwhile, the non-aqueous electrolyte for a lithium secondary battery of the present invention may include an additive in which lithium difluorophosphate, fluorobenzene, tetravinylsilane, and a compound containing one sulfonate group or sulfate group are mixed together. [68] [69] At this time, lithium difluorophosphate (LiDFP) represented by the following formula (1), one of the mixed additive components, is a component for improving the long-term life characteristics of the secondary battery, and is electrochemically decomposed on the surface of the positive and negative electrodes to be stable. By forming an SEI film, exposure to non-aqueous electrolyte can be prevented. As a result, it is possible to improve the durability of the battery by suppressing the generation of O 2 from the positive electrode and suppressing side reactions between the positive electrode and the electrolyte. In addition, since the difluorophosphate structure is reduced when the battery is driven, a strong and stable SEI film can be formed on the surface of the negative electrode, thereby improving the durability of the battery and improving high temperature storage characteristics. [70] [Formula 1] [71] [72] [73] In addition, fluorobenzene represented by the following formula (2), which is one of the mixed additive components, is a component for improving stability during overcharging, and the product decomposed at a specific potential forms a polymer layer on the anode and cathode surfaces, so that the non-aqueous electrolyte and By preventing the side reaction of the electrode, it is possible to improve the high temperature storage stability of the lithium secondary battery. [74] [Formula 2] [75] [76] [77] In addition, tetravinyl silane (TVS) represented by the following Formula 3, which is one of the mixed additive components, forms a solid SEI film through physical adsorption and electrochemical reaction on the anode and cathode surfaces, It can prevent the exposure of the cathode. As a result, since a side reaction between the non-aqueous electrolyte and the electrode at high temperature is suppressed and resistance increase is prevented, high temperature storage stability of the lithium secondary battery can be improved. [78] [Chemical Formula 3] [79] [80] [81] In addition, a compound containing one sulfonate group or sulfate group, which is one of the mixed additive components, can form a stable film that does not crack even when stored at a high temperature on the surface of the negative electrode. The negative electrode covered with such a film can suppress the decomposition of the non-aqueous solvent by the negative electrode active material during high temperature storage even when a carbon material highly crystallized by activity such as natural graphite or artificial graphite is used for the negative electrode, thereby suppressing gas generation. have. Therefore, it is possible to improve the stability of the lithium secondary battery at high temperature and the cycle life and capacity characteristics during high temperature storage, and suppress a decrease in resistance. [82] Specifically, the compound containing one sulfonate group or sulfate group is ethylene sulfate (Esa) represented by Formula 4a, trimethylene sulfate (TMS) represented by Formula 4b, and Formula 4c. Methyl trimethylene sulfate (MTMS) represented by the following formula 4d, 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,4-butene sultone , And 1-methyl-1,3-propene sultone and 1,3-propene sultone (PRS) represented by the following Chemical Formula 4e. It may be at least one selected from the group consisting of. [83] [Formula 4a] [84] [85] [86] [Formula 4b] [87] [88] [89] [Formula 4c] [90] [91] [92] [Formula 4d] [93] [94] [95] [Formula 4e] [96] [97] [98] Specifically, the compound containing one sulfonate group or sulfate group may be at least one of ethylene sulfate, trimethylene sulfate, 1,3-propane sultone, and 1,3-propene sultone. [99] The compound containing such one sulfonate group or sulfate group is up to 6.5% by weight or less, specifically 0.1% to 6.5% by weight, more specifically 0.5% to 4.0% by weight based on the total weight of the non-aqueous electrolyte for a lithium secondary battery. Can be included. [100] At this time, when the total content of the compound containing a sulfonate group or sulfate group in the non-aqueous electrolyte for a lithium secondary battery exceeds 6.5% by weight, an excessively thick film may be formed, thereby increasing resistance and deteriorating output. [101] [102] On the other hand, in the case of a compound containing both or more sulfonate groups and/or sulfate groups, such as the compound represented by the following formula (5), since the reduction reactivity is high, the non-aqueous electrolyte itself is highly likely to be denatured. Moreover, as the component ratio of S and O increases inside the film formed on the surface of the anode or cathode, the ion conductivity increases and the output characteristics improve, while the side reaction with the electrolyte increases, making it difficult to play the role as a passivation film. Therefore, the durability of the secondary battery is relatively reduced at high temperatures, and its use is avoided. [103] [Formula 5] [104] [105] [106] On the other hand, the lithium difluorophosphate, fluorobenzene, tetravinylsilane and a compound containing one sulfonate group or sulfate group is 1: 2 to 8: 0.05 to 0.3: 0.5 to 2, specifically 1: 2 to 6 : 0.05 to 0.3: may be included in a weight ratio of 0.5 to 1.5. [107] That is, when the components of the additive are mixed in the above ratio in the non-aqueous electrolyte of the present invention, a secondary battery with improved overall performance can be manufactured. [108] For example, when the weight ratio of fluorobenzene to lithium difluorophosphate is 8 or less, an increase in internal resistance of the battery due to excessive use of additives can be prevented. In addition, when the weight ratio of the fluorobenzene is 2 or more, it may bring about an effect of improving stability during overcharging. [109] In addition, when the weight ratio of tetravinylsilane to the lithium difluorophosphate is 0.3 or less, side reactions caused by excess tetravinylsilane can be prevented from increasing the resistance of the battery, thereby reducing cycle life characteristics. Can be prevented. In addition, when the weight ratio of the tetravinylsilane is 0.05 or more, the gas generation reduction effect and the stabilization effect upon forming the SEI film may be obtained. [110] In addition, when the weight ratio of the compound containing one sulfonate group or sulfate group to the lithium difluorophosphate is 2 or less, it is possible to secure a stabilizing effect upon formation of the SEI film, thereby improving high temperature storage characteristics and cycle life characteristics. . In addition, when the weight ratio of the compound containing one sulfonate group or sulfate group is 0.5 or more, it is possible to improve the stability of the SEI film without increasing resistance and to suppress side reactions of the electrolyte solution, thereby improving performance. [111] [112] In addition, in the nonaqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention, the additive is included in 1% to 18% by weight, specifically 8% to 10% by weight based on the total weight of the nonaqueous electrolyte for a lithium secondary battery. I can. [113] At this time, when the content of the additive is 18% by weight or less, gas generation effect due to the use of the additive can be improved, and each component is prevented from remaining in excess, thereby preventing an increase in resistance due to side reactions, and Since a stable SEI film can be formed on the surface, high temperature stability of a lithium secondary battery can be improved. [114] In addition, when the content of the additive is 1% by weight or more, it is possible to form a stable (SEI) film on the surface of the negative electrode, as well as suppress decomposition of the electrolyte solution due to reaction between the electrolyte solution and the negative electrode. The expected effect can be met. [115] If the content of the mixed additive exceeds 18% by weight, as the viscosity of the non-aqueous electrolyte increases due to an excessive amount of the additive, solubility and wettability are deteriorated, and output characteristics and cycle life characteristics may be deteriorated. , [116] [117] When the lithium ion battery is initially charged, lithium ions from the lithium metal oxide used as the positive electrode move to the carbon (crystalline or amorphous) electrode used as the negative electrode, and are intercalated into the carbon of the negative electrode, where lithium is highly reactive. Therefore, it reacts with the carbon-based cathode to form organic materials and Li 2 CO 3 , Li 2 O, LiOH, etc., and these form an SEI film on the surface of the cathode. Once the SEI film is formed at the time of initial charge, it prevents the reaction between lithium ions and carbon-based negative electrodes or other materials when charging and discharging by the battery is repeated afterwards, and serves as an ion tunnel through which only lithium ions pass between the electrolyte and the negative electrode. Will perform. By the ion tunnel effect, the SEI film blocks the movement of organic solvents of an electrolyte solution having a high molecular weight, such as EC, DMC, DEC, PP, etc., to the carbon-based negative electrode, so that lithium ions are co-inserted into the carbon-based negative electrode ( cointercalation) prevents the collapse of the structure of the carbon-based cathode. That is, after the film is formed, the lithium ions do not react with the carbon-based negative electrode or other materials again, so that the amount of lithium ions is reversibly maintained during charging and discharging by using the battery. [118] In other words, the carbon material of the negative electrode reacts with the electrolyte during initial charging to form a passivation layer on the surface of the negative electrode, so that no further electrolyte decomposition occurs and stable charge and discharge can be maintained.At this time, the passivation of the negative electrode surface The amount of charge consumed in the formation of the layer is an irreversible capacity, and has a characteristic that it does not react reversibly during discharge, and for this reason, the lithium-ion battery does not show any more irreversible reaction after the initial charging reaction and can maintain a stable life cycle. . [119] However, when the lithium ion battery is stored at high temperature in a fully charged state (e.g., stored at 60℃ after 100% charging over 4.15V), the SEI film gradually collapses due to increased electrochemical energy and thermal energy over time. Have. [120] This collapse of the SEI film exposes the negative electrode surface, and the exposed negative electrode surface is decomposed as the carbonate-based solvent in the electrolyte reacts, causing a continuous side reaction. [121] Such side reactions continuously generate gases, and the main gases generated at this time are CO, CO 2 , CH 4 , C 2 H 6, etc., which vary depending on the type of carbonate used as the electrolyte and the type of the anode active material. Regardless of the type, continuous gas generation at high temperatures increases the internal pressure of the lithium-ion battery, which causes the battery thickness to expand. [122] Thus, the non-aqueous electrolyte for a lithium secondary battery of the present invention includes a mixed additive obtained by mixing a compound containing lithium difluorophosphate, fluorobenzene, tetravinylsilane, and one sulfonate group or sulfate group in a specific ratio, By forming a more stable and robust SEI film on the surface of the negative electrode, it is possible to improve overall performance such as high temperature storage characteristics and life characteristics of lithium secondary batteries by suppressing side reactions of the electrolyte during storage at high temperatures as well as improving low temperature output characteristics. . [123] [124] (4) SEI film forming additive [125] On the other hand, the non-aqueous electrolyte according to an embodiment of the present invention is used together with the mixed additive to form a stable film on the surface of the negative electrode and the positive electrode without significantly increasing initial resistance with the effect of the mixed additive. It may further include an additional additive that can serve as a supplement to suppress decomposition of the solvent in the electrolyte and improve mobility of lithium ions. [126] The additional additive is not particularly limited as long as it is an additive for forming an SEI film capable of forming a stable film on the anode and cathode surfaces. [127] [128] Specifically, the SEI film-forming additive is at least one SEI film selected from the group consisting of a halogen-substituted carbonate compound, a nitrile compound, a cyclic carbonate compound, a phosphate compound, a borate compound, and a lithium salt compound. It may contain a first additive for forming. [129] Specifically, the halogen-substituted carbonate-based compound may include fluoroethylene carbonate (FEC)), and may be included in an amount of 5% by weight or less based on the total weight of the non-aqueous electrolyte. When the content of the halogen-substituted carbonate-based compound exceeds 5% by weight, cell swelling performance may deteriorate. [130] In addition, the nitrile compound is succinonitrile, adiponitrile (Adn), acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, In the group consisting of 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile And at least one or more selected compounds. [131] In this case, when the nitrile-based compound is used together with the above-described mixed additive, effects such as improvement in high temperature characteristics can be expected by stabilizing the positive/negative electrode film. That is, it may serve as a supplement to form the negative SEI film, may play a role of suppressing decomposition of a solvent in the electrolyte, and may play a role of improving the mobility of lithium ions. The nitrile-based compound may be included in an amount of 8% by weight or less based on the total weight of the non-aqueous electrolyte. When the total content of the nitrile-based compound in the non-aqueous electrolyte exceeds 8% by weight, resistance increases due to an increase in a film formed on the electrode surface, and battery performance may deteriorate. [132] The carbonate-based compound mainly forms a stable SEI film on the surface of the negative electrode when the battery is activated, thereby improving the durability of the battery. The cyclic carbonate-based compound may include vinylene carbonate (VC) or vinyl ethylene carbonate, and may include 3% by weight or less based on the total weight of the non-aqueous electrolyte. When the content of the cyclic carbonate-based compound in the non-aqueous electrolyte exceeds 3% by weight, cell swelling inhibiting performance and initial resistance may be deteriorated. [133] In addition, since the phosphate-based compound stabilizes PF 6 anions in the electrolyte and helps to form positive and negative electrodes, it is possible to improve the durability of the battery. These phosphate compounds are difluoro (bisoxalato) phosphate (LiDFOP), tetramethyl trimethyl silyl phosphate (LiTFOP), trimethyl silyl phosphite (TMSPi), tris (2,2,2-trifluoroethyl) phosphate (TFEPa) and tris (trifluoroethyl) phosphite (TFEPi) may include one or more compounds selected from the group consisting of, and may be included in an amount of 3% by weight or less based on the total weight of the non-aqueous electrolyte. [134] The borate-based compound promotes ion pair separation of lithium salts, thereby improving the mobility of lithium ions, lowering the interfacial resistance of the SEI film, and also substances such as LiF that are generated during battery reactions and are difficult to separate. By dissociation, problems such as generation of fluoric acid gas can be solved. Such borate-based compounds may include lithium bioxalyl borate (LiBOB, LiB(C 2 O 4 ) 2 ), lithium oxalyldifluoroborate or tetramethyltrimethylsilylborate (TMSB), based on the total weight of the non-aqueous electrolyte. It may be included in less than 3% by weight. [135] In addition, the lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and includes at least one compound selected from the group consisting of LiODFB and LiBF 4 , and is 3% by weight or less based on the total weight of the non-aqueous electrolyte. Can include. [136] The first additive for forming the SEI film may be used in combination of two or more, and may be included in an amount of 10% by weight or less, specifically 0.01% to 10% by weight, preferably 0.1 to 5.0% by weight based on the total amount of the electrolyte. . [137] When the content of the first additive for forming the SEI film is less than 0.01% by weight, the high-temperature storage characteristics and gas reduction effect to be realized from the additive are insignificant, and when the content of the first additive for forming the SEI film exceeds 10% by weight During charging and discharging of the battery, there is a possibility that side reactions in the electrolyte solution may occur excessively. In particular, if the first additive for forming the SEI film is added in an excessive amount, it may not be sufficiently decomposed and may remain unreacted or precipitated in the electrolyte at room temperature. Accordingly, the resistance may increase and the life characteristics of the secondary battery may decrease. [138] [139] On the other hand, the non-aqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention is diphenyl disulfide (DPDS), di-p-tolyl disulfide (DTDS), and bis (4- At least one SEI film-forming second additive selected from the group consisting of methoxyphenyl) disulfide (BMPDS) may be further included. [140] The second additive for forming the SEI film contributes to formation of a stable protective film on the surface of the negative electrode carbon material. This protective film maintains a stable state even when charging and discharging are repeated. By the action of this protective film, the non-aqueous solvent in the electrolytic solution is electrochemically reduced and gas generation is suppressed. As a result, peeling of the negative electrode carbon material from the negative electrode can be suppressed and the cycle characteristics can be improved. [141] In addition, in DPDS, DTDS, and BMPDS, the reaction product of the non-aqueous solvent and the carbon-based negative electrode during the formation of the protective film acts on the ends of the polar groups present in the binders PVDF and P (VDF-HFP) to prevent the swelling of the binder by the non-aqueous solvent. Suppression and adhesion between electrode materials is maintained. Thereby, it is possible to exhibit an effect of suppressing an increase in the impedance of the electrode and further improving the cycle characteristics. [142] The second additive for forming the SEI film may be included in an amount of 0.6% by weight or less, specifically 0.1% to 0.6% by weight, based on the total weight of the non-aqueous electrolyte for a lithium secondary battery. If the content of the additive is 0.1% by weight or more, the desired effect can be obtained from the additive, and when the content is less than 0.6% by weight, side reactions due to excess additives can be prevented. [143] [144] Lithium secondary battery [145] In addition, in an embodiment of the present invention [146] In a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and a non-aqueous electrolyte, [147] The non-aqueous electrolyte provides a lithium secondary battery comprising the non-aqueous electrolyte of the present invention. [148] In this case, the positive electrode may include a lithium-nickel-manganese-cobalt-based oxide as a positive electrode active material. [149] [150] Meanwhile, in the lithium secondary battery of the present invention, an electrode assembly may be formed by sequentially stacking a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and at this time, the positive electrode, the negative electrode, and the separator forming the electrode assembly are conventional methods. Anything that was manufactured as a lithium secondary battery can be used. [151] [152] (1) anode [153] The positive electrode may be manufactured by forming a positive electrode mixture layer on the positive electrode current collector. The positive electrode mixture layer may be formed by coating a positive electrode slurry including a positive electrode active material, a binder, a conductive material, and a solvent on a positive electrode current collector, followed by drying and rolling. [154] The positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or carbon on the surface of aluminum or stainless steel. , Nickel, titanium, silver, or the like may be used. [155] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing lithium and at least one metal such as cobalt, manganese, nickel or aluminum. have. More specifically, the lithium composite metal oxide is a lithium-nickel-manganese-cobalt-based oxide (for example, Li(Ni p Co q Mn r1 )O 2 (herein , 0