Specification 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. 2018-0016782 filed on February 12, 2018, and all contents disclosed in the documents of the Korean patent application are 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 comprising a non-aqueous electrolyte additive having an excellent effect of removing decomposition products generated from a lithium salt, and a lithium secondary battery having improved high-temperature storage characteristics by including the same. Background [6] As personal IT devices and computer networks are developed due to the development of the information society, the overall society's dependence on electrical energy increases, and there is a demand for technology development to efficiently store and utilize electrical energy. [7] Among the technologies developed for this, the most suitable technology for various uses is the technology based on secondary batteries. In the case of a secondary battery, it can be miniaturized to the extent that it can be applied to personal IT devices, and it can be applied to electric vehicles and power storage devices. Among these secondary battery technologies, a lithium-ion battery, which is a battery system with the highest energy density in theory, is in the spotlight, and is currently applied to various devices. [8] In the case of such a lithium ion battery, unlike the early days when lithium metal was directly applied to the system, it is composed of a positive electrode made of a transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte, and a separator. [9] Among these, electrolytes are known as constituents that have a great influence on the stability and safety of lithium-ion batteries, and many studies are being conducted on this. [10] In the case of an electrolyte for a lithium ion battery, it is composed of a lithium salt, an organic solvent that dissolves it, and a functional additive. In order to improve the electrochemical properties of the battery, proper selection of these components is important. Representative lithium salts currently used include LiPF 6 , LiBF 4 , LiFSI (lithium fluorosulfonyl imide, LiN(SO 2 F) 2 ), LiTFSI (lithium (bis)trifluoromethanesulfonyl imide, LiN(SO 2 CF 3 ) 2 ) or LiBOB ( Lithium bis(oxalate) borate, LiB(C 2 O 4 ) 2 ) are used, and in the case of organic solvents, ester-based organic solvents or ether-based organic solvents are used. [11] In the case of such a lithium-ion battery, an increase in resistance and a decrease in capacity during charge/discharge or storage at high temperatures are suggested as major problems in performance degradation, and one of the causes of such problems is the degradation of electrolyte at high temperatures. It is a side reaction that occurs as a result of decomposition of salts at high temperatures. When the by-products of these salts decompose the film formed on the surface of the anode and the cathode after activation, there is a problem of degrading the passivation ability of the film, and this causes additional decomposition of the electrolyte and the accompanying self-discharge. There is. [12] Among the electrode materials of lithium-ion batteries, especially for negative electrodes, graphite-based negative electrodes are used in most cases. In the case of graphite, its operating potential is 0.3 V ( vs. Li/Li + ) or less, and the electricity of the electrolyte used in lithium-ion batteries. Lower than the chemical stability window, the currently used electrolyte is reduced and decomposed. This reduction and decomposition product allows lithium ions to permeate, but forms a solid electrolyte interphase (SEI) film that suppresses further decomposition of the electrolyte. However, when the SEI film does not have sufficient passivation capability to suppress further electrolyte decomposition, the electrolyte is further decomposed during storage and the charged graphite is self-discharged, resulting in a decrease in the potential of the entire battery. [13] One of the factors that can affect the passivation ability is an acid such as HF and PF 5 produced by pyrolysis of LiPF 6 , a lithium salt widely used in lithium ion batteries . As the electrode surface is deteriorated due to the attack of the acid, a transition metal is eluted from the anode, thereby increasing resistance, and loss of a redox center may cause a decrease in capacity. In the case of the eluted metal ions, they are electrodeposited to the negative electrode, resulting in an increase in irreversible capacity due to the consumption of electrons due to the electrodeposition of metal and additional electrolyte decomposition, resulting in a decrease in cell capacity, as well as increased resistance and self-discharge of the graphite negative electrode. Can cause. [14] Therefore, in order to maintain the passivation ability of the SEI film at high temperature, an electrolyte solution additive containing double or triple bonds that can easily occur reductive decomposition is introduced, or from by-products generated due to heat/moisture, such as LiPF 6 , which is a lithium salt, etc. the resulting decomposition products of HF, PF 5 by removing the like can be referred to fruition a solution for suppressing the damage to the film. [15] [16] (Prior technical literature) Korean Patent Application Publication No. 2013-0116036 Detailed description of the invention Technical challenge [17] An object of the present invention is to provide a non-aqueous electrolyte for a lithium secondary battery comprising a non-aqueous electrolyte additive having an excellent effect of removing decomposition products generated from a lithium salt that may occur inside the electrolyte. [18] In addition, the present invention is to provide a lithium secondary battery having improved high-temperature storage characteristics by including the non-aqueous electrolyte for a lithium secondary battery. Means of solving the task [19] In one embodiment of the present invention for achieving the above object, [20] Lithium salt; [21] Organic solvent; And [22] It provides a non-aqueous electrolyte for a lithium secondary battery comprising a compound represented by the following formula (1) as an additive. [23] [Formula 1] [24] [25] In Formula 1, [26] R a to R c are each independently a substituted or unsubstituted alkylene group having 2 to 15 carbon atoms. [27] [28] In Formula 1, R a to R c are each independently a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and more specifically, R a to R c are each independently substituted or unsubstituted C 3 to 7 It is an alkylene group of. [29] Specifically, in Formula 1, R a to R c are each independently -CR 1 H-CR 2 H-CR 3 H- (In this case, R 1 , R 2 and R 3 are each independently hydrogen or 1 carbon number To 2 alkyl groups.), -CR 4 H-CR 5 H-CR 6 H-CR 7 H- (At this time, R 4 , R 5 , R 6 and R 7 are each independently hydrogen or having 1 to 2 carbon atoms. It is an alkyl group.) and -CR 8 H-CR 9 H-CR 10 H-CR 11H-CR 12 H- (In this case, R 8 , R 9 , R 10 , R 11 and R 12 are each independently hydrogen or an alkyl group having 1 to 2 carbon atoms.) It may be at least one selected from the group consisting of. [30] More specifically, in Formula 1, R a to R c are each independently -CH 2 -CH 2 -CH 2 -, -CH 2 -CH 2 -CH 2 -CH 2 -and -CH 2 -CH 2 It may be at least one selected from the group consisting of -CH 2 -CH 2 -CH 2 -. [31] More specifically, the compound represented by Formula 1 may be represented by the following Formula 1a. [32] [Formula 1a] [33] [34] [35] The compound represented by Formula 1 may be included in an amount of 0.1% to 2.0% by weight, specifically 0.1% to 1.7% by weight, based on the total weight of the non-aqueous electrolyte. [36] [37] In addition, the non-aqueous electrolyte for a lithium secondary battery is a cyclic carbonate compound, a halogen-substituted carbonate compound, a sultone compound, a sulfate compound, a phosphate compound, a borate compound, a nitrile compound, a benzene compound, an amine compound, and a silane. It may further include at least one additional additive selected from the group consisting of compounds and lithium salt compounds. [38] [39] In addition, another embodiment of the present invention provides a lithium secondary battery including the non-aqueous electrolyte for a lithium secondary battery of the present invention. Effects of the Invention [40] In the present invention, a non-aqueous electrolyte for lithium secondary batteries containing a Lewis base-based compound capable of scavenging decomposition products such as HF or PF 5 caused by anionic decomposition of lithium salts inside the battery during charging and discharging By providing, it is possible to manufacture a lithium secondary battery with improved initial discharge capacity and high temperature storage characteristics. Brief description of the drawing [41] 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 above-described invention, so the present invention is limited to the matters described in such drawings. It is limited and should not be interpreted. [42] 1 is a graph showing the degree of change in open-circuit voltage (OCV) of a cell according to high temperature storage time in Experimental Example 1 of the present invention. [43] 2 is a graph showing an evaluation result of an increase in discharge capacity and resistance according to storage time of a lithium secondary battery of Experimental Example 2 of the present invention. [44] 3 is a graph showing the discharge capacity retention rate according to the cycle of the lithium secondary battery of Experimental Example 3 of the present invention. Best mode for carrying out the invention [45] Hereinafter, the present invention will be described in more detail. [46] Terms and words used in the specification and claims are not to 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. [47] [48] In the conventional lithium secondary battery, when the non-aqueous electrolyte is decomposed during initial charging and discharging, a film having a passivation capability is formed on the surfaces of the positive electrode and the negative electrode, so that high-temperature storage characteristics can be greatly improved. However, such a film may be deteriorated by an acid such as HF and PF 5 generated by anionic pyrolysis such as LiPF 6 , a lithium salt widely used in lithium ion batteries . Due to such acid attack, the transition metal element is eluted from the anode, the surface resistance of the electrode increases due to the change in the structure of the surface, and the theoretical capacity decreases as the redox center metal elements are lost, resulting in a decrease in the expression capacity. . In addition, in the case of the eluted transition metal ions, they are electrodeposited to the negative electrode reacting in a strong reduction potential band, and not only consume electrons, but also destroy the film when electrodeposited, thereby exposing the surface of the negative electrode, thereby causing an additional electrolyte decomposition reaction. Cause. As a result, as the resistance of the cathode increases and the irreversible capacity increases, there is a problem that the capacity of the cell continuously decreases. [49] Thus, in the present invention, by including a Lewis salt additive as a non-aqueous electrolyte additive in the battery, the acid caused by decomposition of the lithium salt is removed, thereby preventing deterioration of the SEI film or elution of the transition metal from the positive electrode during high temperature storage. It is intended to provide a non-aqueous electrolyte and a lithium secondary battery including the same. [50] [51] Non-aqueous electrolyte for lithium secondary batteries [52] Specifically, in one embodiment of the present invention [53] Lithium salt; [54] Organic solvent; And [55] It provides a non-aqueous electrolyte for a lithium secondary battery comprising a compound represented by the following formula (1) as an additive. [56] [Formula 1] [57] [58] In Formula 1, [59] R a to R c are each independently a substituted or unsubstituted alkylene group having 2 to 15 carbon atoms. [60] [61] (1) lithium salt [62] First, in the non-aqueous electrolyte for a lithium secondary battery 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, F - as an anion , Cl - , Br - , I - , NO 3 - , N (CN) 2 - , BF 4 - , ClO 4 - , B 10 Cl 10 - , AlCl 4 - , AlO 4 - , PF 6 - , CF 3 SO 3 - , CH 3 CO 2 - , CF 3 CO 2 - , AsF 6 - , SbF 6 - , CH 3 SO 3 - , (CF 3 CF 2 SO 2 ) 2 N - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , 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 - , (CF 3) 6 P - , C 4 F 9 SO 3 - , CF 3 CF 2 SO 3 - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , CF 3 (CF 2 ) 7 the SO 3 - and SCN -At least any one selected from the group consisting of may be mentioned. [63] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF 4 , LiClO 4 , LiB 10 Cl 10 , LiAlCl 4 , LiAlO 4 , LiPF 6 , LiCF 3 SO 3 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiCH 3 SO 3 , LiFSI (Lithium bis(fluorosulfonyl)imide, LiN(SO 2 F) 2), LiBETI (lithium bisperfluoroethanesulfonimide, LiN(SO 2 CF 2 CF 3 ) 2 and LiTFSI (lithium (bis) trifluoromethanesulfonimide, LiN(SO 2 CF 3 ) 2 )), a single substance or a mixture of two or more selected from the group consisting of In addition to these, lithium salts commonly used in electrolytes of lithium secondary batteries can be used without limitation. [64] The lithium salt may be appropriately changed within a range that is usually usable, but in order to obtain an optimum effect of forming a film for preventing corrosion on the electrode surface, it is included in a concentration of 0.8 M to 4.0 M, specifically 1.0 M to 3.0 M in the electrolyte. I can. [65] When the concentration of the lithium salt is less than 0.8 M, the effect of improving the low-temperature output of the lithium secondary battery and improving the cycle characteristics during high-temperature storage is insignificant. I can. [66] [67] (2) organic solvent [68] In addition, in the non-aqueous electrolyte for a lithium secondary battery, the organic solvent includes at least one organic solvent selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent. can do. [69] Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixed organic solvent thereof. [70] The cyclic carbonate-based organic solvent is an organic solvent having a high viscosity and has a high dielectric constant, and is an organic solvent capable of dissociating lithium salts in an electrolyte well.Specific examples thereof are ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene Carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate may contain at least one or more organic solvents selected from the group consisting of carbonate, among which ethylene carbonate It may include. [71] In addition, the linear carbonate-based organic solvent is an organic solvent having a low viscosity and a low dielectric constant, and representative examples thereof are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate ( EMC), at least one organic solvent selected from the group consisting of methylpropyl carbonate and ethylpropyl carbonate may be used, and specifically ethylmethyl carbonate (EMC) may be included. [72] In addition, the organic solvent is a linear ester-based organic solvent and/or a cyclic ester-based organic solvent to the mixed organic solvent of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent in order to prepare an electrolyte solution having high ionic conductivity. It can also be included. [73] Such a linear ester-based organic solvent may be at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. Can be lifted. [74] In addition, as the cyclic ester-based organic solvent, at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone Can be lifted. [75] Meanwhile, the organic solvent may be used by adding an organic solvent commonly used in an electrolyte solution for a lithium secondary battery, without limitation, if necessary. For example, it may further include at least one organic solvent of an ether-based organic solvent, an amide-based organic solvent, and a nitrile-based organic solvent. [76] [77] (3) additive [78] The non-aqueous electrolyte for a lithium secondary battery of the present invention may include a compound represented by the following formula (1) as an additive. [79] [Formula 1] [80] [81] In Formula 1, [82] R a to R c are each independently a substituted or unsubstituted alkylene group having 2 to 15 carbon atoms. [83] At this time, in Formula 1, R a to R c are each independently a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and more specifically, R a to R c are each independently substituted or unsubstituted C 3 to It is an alkylene group of 7. [84] Specifically, in Formula 1, R a to R c are each independently -CR 1 H-CR 2 H-CR 3 H- (In this case, R 1 , R 2 and R 3 are each independently hydrogen or 1 carbon number To 2 alkyl groups.), -CR 4 H-CR 5 H-CR 6 H-CR 7 H- (At this time, R 4 , R 5 , R 6 and R 7 are each independently hydrogen or having 1 to 2 carbon atoms. It is an alkyl group.) and -CR 8 H-CR 9 H-CR 10 H-CR 11H-CR 12 H- (In this case, R 8 , R 9 , R 10 , R 11 and R 12 are each independently hydrogen or an alkyl group having 1 to 2 carbon atoms.) It may be at least one selected from the group consisting of. [85] More specifically, in Formula 1, R a to R c are each independently -CH 2 -CH 2 -CH 2 -, -CH 2 -CH 2 -CH 2 -CH 2 -and -CH 2 -CH 2 It may be at least one or more selected from the group consisting of -CH 2 -CH 2 -CH 2 -. [86] More specifically, the compound represented by Formula 1 may be a compound represented by Formula 1a below. [87] [Formula 1a] [88] [89] [90] The compound of Formula 1 may be included in an amount of 0.1% to 2.0% by weight, specifically 0.1% to 1.7% by weight, more preferably 0.5% to 1.5% by weight based on the total weight of the non-aqueous electrolyte. [91] When the additive is included in the above range, it is possible to manufacture a secondary battery with further improved overall performance. If the content of the additive is less than 0.1% by weight, HF or PF 5 can be removed, but the removal effect may be insignificant as time passes, and if it exceeds 2.0% by weight, storage at high temperature as a side reaction due to decomposition of excessive additives. Resistance can be increased. [92] Therefore, when the additive is contained in an amount of 0.1% by weight or more, specifically 0.5% by weight or more, and 2.0% by weight or less, specifically 1.7% by weight or less, and more specifically 1.5% by weight or less, side reactions by the additive, capacity It is possible to more effectively remove acids such as HF and PF 5 , which are decomposition products of lithium salts, while suppressing disadvantages such as lowering and increasing resistance as much as possible . [93] [94] As described above, in the present invention, by including a Lewis base-based compound containing a nitrogen element, such as the compound represented by Formula 1, as an electrolyte solution additive, by-products causing deterioration at high temperatures of the battery, such as lithium salts By removing the acid that may occur due to decomposition, problems such as deterioration of the SEI film or elution of transition metals from the anode can be improved. [95] For example, in the case of the compound represented by Formula 1, the P=O functional group may act as a Lewis base and react with Lewis acids such as HF and PF 5 , which are decomposition products generated by the decomposition of anions, and scavenging them. In addition, the tertiary nitrogen element, which is a strong electron-donating group bound to P, makes it possible to maintain this capacity as a Lewis base quite strongly. Therefore, deterioration behavior due to chemical reaction of the positive or negative surface film caused by Lewis acid can be suppressed, preventing further electrolyte decomposition of the battery due to the destruction of the film, and further reducing the self-discharge of the secondary battery for high temperature storage. The properties can be improved. [96] [97] (4) additional additives [98] In addition, the non-aqueous electrolyte for a lithium secondary battery of the present invention prevents negative electrode collapse due to decomposition of the non-aqueous electrolyte in a high-power environment, or further enhances the effect of low-temperature high-rate discharge characteristics, high-temperature stability, prevention of overcharge, and inhibition of battery expansion at high temperatures. In order to improve, if necessary, additional additives may be further included in the non-aqueous electrolyte. [99] Typical examples of such additional additives include cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, and silane compounds. It may include at least one or more additional additives selected from the group consisting of compounds and lithium salt compounds. [100] The cyclic carbonate-based compound may be vinylene carbonate (VC) or vinyl ethylene carbonate. [101] The halogen-substituted carbonate-based compound may include fluoroethylene carbonate (FEC)). [102] The sultone-based compounds include 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone and 1-methyl-1,3 -At least one or more compounds selected from the group consisting of propene sultones. [103] The sulfate-based compound may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS). [104] The phosphate-based compound is lithium difluoro (bisoxalato) phosphate, lithium difluoro phosphate, tetramethyl trimethyl silyl phosphate, trimethyl silyl phosphite, tris (2,2,2-trifluoroethyl) phosphate and tris And one or more compounds selected from the group consisting of (trifluoroethyl) phosphite. [105] Examples of the borate-based compound include tetraphenylborate and lithium oxalyldifluoroborate. [106] The nitrile compound is succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzo At least one selected from the group consisting of nitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile And compounds. [107] The benzene-based compound may be fluorobenzene, the amine-based compound may be triethanolamine or ethylene diamine, and the silane-based compound may be tetravinylsilane. [108] The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and is selected from the group consisting of LiPO 2 F 2 , LiODFB, LiBOB (lithium bisoxalatoborate (LiB(C 2 O 4 ) 2 ) and LiBF 4 ). One or more compounds may be mentioned. [109] Among these additional additives, when vinylene carbonate, vinylethylene carbonate, or succinonitrile is included, a more robust SEI film may be formed on the negative electrode surface during the initial activation process of the secondary battery. [110] When the LiBF 4 is included, generation of gas that may be generated due to decomposition of the electrolyte solution at high temperature may be suppressed, and high temperature stability of the secondary battery may be improved. [111] [112] Meanwhile, two or more of the additional additives may be mixed and used, and may be included in an amount of 0.01 to 50% by weight, specifically 0.01 to 10% by weight, and preferably 0.05 to 5% by weight based on the total weight of the non-aqueous electrolyte. Can be When the content of the additional additive is less than 0.01% by weight, the effect of improving the low-temperature output and improving the high-temperature storage characteristics and high-temperature life characteristics of the battery is insignificant. In this case, there is a possibility that excessive side reactions in the electrolyte may occur. In particular, when the additives for forming the SEI film are added in an excessive amount, they may not be sufficiently decomposed at high temperature, and thus may be present as unreacted or precipitated in the electrolyte at room temperature. Accordingly, a side reaction may occur in which the lifespan or resistance characteristics of the secondary battery are deteriorated. [113] [114] Lithium secondary battery [115] In addition, another embodiment of the present invention provides a lithium secondary battery including the non-aqueous electrolyte for a lithium secondary battery of the present invention. [116] [117] On the other hand, the lithium secondary battery of the present invention can be manufactured by forming an electrode assembly in which a positive electrode, a negative electrode, and a separator are sequentially stacked between the positive electrode and the negative electrode, stored in a battery case, and then introduced with the non-aqueous electrolyte of the present invention. [118] The method of manufacturing the lithium secondary battery of the present invention may be manufactured and applied according to a conventional method known in the art, and will be described in detail later. [119] [120] (1) anode [121] The positive electrode may be prepared 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. [122] 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. [123] 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-manganese oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), a lithium-cobalt oxide (eg, LiCoO 2, etc.), a lithium-nickel oxide (E.g., LiNiO 2 ), lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O 2 (0