Title of the invention: 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. 2017-0146223 filed on November 03, 2017 and Korean Patent Application No. 2018-0132195 filed on October 31, 2018, and The content is incorporated as part of this specification. [3] [4] Technical field [5] The present invention relates to an electrolyte for a lithium secondary battery and a lithium secondary battery including the same. Background [6] Recently, interest in energy storage technology is increasing. In particular, as the fields of application are expanded to mobile phones, camcorders, notebook PCs, and even electric vehicles, research and efforts to develop energy storage technologies are increasingly being materialized. [7] The electrochemical device is the field that attracts the most attention among these energy storage technology fields, and among them, interest in a lithium secondary battery capable of charging and discharging is on the rise. [8] In a lithium secondary battery, a positive electrode active material and a negative electrode active material are applied to a current collector with an appropriate thickness, or the active material itself is formed in a film shape of an appropriate length, and then wound or stacked together with a separator, which is an insulator, to manufacture an electrode assembly. It is manufactured by putting an electrode assembly in a similar container and then injecting an electrolyte. [9] In this case, the electrolyte may generally be a liquid electrolyte containing an electrolyte solvent in which a lithium salt is dissolved or a gel polymer electrolyte further containing a matrix polymer. [10] Examples of the electrolyte solvent include ethylene carbonate, propylene carbonate, dimethoxyethane, gamma butyrolactone, N,N-dimethylformamide, tetrahydrofuran or acetonitrile. [11] On the other hand, the electrolyte solvent causes a side reaction at high voltage, and when stored at a high temperature for a long time, an oxidation reaction may be caused, as well as an exothermic reaction by easily reacting with a dendrite-type Li metal formed on the negative electrode. In particular, when overcharging proceeds above a certain SOC, the oxidation reaction of the electrolyte is accelerated, and the exothermic reaction between the Li metal on the surface of the negative electrode and the electrolyte formed by excessive Li migration from the positive electrode to the negative electrode intensifies, causing the battery to ignite and explode. have. [12] Accordingly, in order to improve the stability and high output characteristics of the lithium secondary battery, it is necessary to develop an electrolyte for a lithium secondary battery in which not only the wetting characteristics of the electrolyte can be improved, but also the reactivity with the lithium metal is suppressed. [13] Prior art literature [14] Republic of Korea Patent Publication No. 2014-0066163 Detailed description of the invention Technical challenge [15] The present invention is to provide an electrolyte for a lithium secondary battery with improved wettability by lowering the surface tension with the electrode surface. [16] In addition, the present invention is to provide a lithium secondary battery including the lithium secondary battery electrolyte. Means of solving the task [17] In order to solve the above problem, in one embodiment of the present invention [18] Lithium salt, [19] Organic solvent and [20] It provides an electrolyte for a lithium secondary battery comprising an oligomer represented by the following Formula 1 or a polymer derived from an oligomer represented by Formula 1. [21] [Formula 1] [22] [23] In Formula 1, [24] R 1 and R 2 are each independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, [25] R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, [26] R 5 is hydrogen or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, [27] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [28] z and x are the number of repeat units, [29] z is an integer from 1 to 10, [30] x is an integer from 1 to 15, [31] n is an integer of 1 to 3. [32] [33] Specifically, in Formula 1, the aliphatic hydrocarbon group of R'is (a) a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms, a substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms, and a substituted or unsubstituted At least one alicyclic hydrocarbon group selected from the group consisting of a substituted or unsubstituted heterocycloalkylene group having 2 to 20 carbon atoms and (b) a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, and a substituted or unsubstituted C 1 to C 20 At least one aliphatic hydrocarbon selected from the group consisting of at least one linear hydrocarbon group selected from the group consisting of an alkoxyylene group, a substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms, and a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms It includes at least one selected from the group consisting of groups, [34] The aromatic hydrocarbon group of R′ may include at least one selected from the group consisting of a substituted or unsubstituted arylene group having 6 to 20 carbon atoms and a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms. [35] [36] More specifically, in Formula 1, the aliphatic hydrocarbon group of R'is a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms, a substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms, and a substituted or unsubstituted It may include at least one alicyclic hydrocarbon group selected from the group consisting of a heterocycloalkylene group having 2 to 20 carbon atoms. [37] [38] Meanwhile, the oligomer represented by Formula 1 may be at least one selected from the group consisting of oligomers represented by Formulas 1a and 1b below. [39] [Formula 1a] [40] [41] In Formula 1a, [42] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [43] z1 and x1 are the number of repeat units, [44] z1 is an integer from 1 to 10, [45] x1 is an integer in any one of 1-15. [46] [47] [Formula 1b] [48] [49] In Formula 1b, [50] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [51] z2 and x2 are the number of repeat units, [52] z2 is an integer from 1 to 10, [53] x2 is an integer in any one of 1-15. [54] [55] More specifically, the oligomer represented by Formula 1 may be at least one selected from the group consisting of oligomers represented by Formulas 1a-1 and 1b-1 below. [56] [Formula 1a-1] [57] [58] In Formula 1a-1, [59] z1 and x1 are the number of repeat units, [60] z1 is an integer from 1 to 10, [61] x1 is an integer in any one of 1-15. [62] [63] [Formula 1b-1] [64] [65] In Formula 1b-1, [66] z2 and x2 are the number of repeat units, [67] z2 is an integer from 1 to 10, [68] x2 is an integer in any one of 1-15. [69] [70] The electrolyte for a lithium secondary battery of the present invention may be a liquid electrolyte containing an oligomer represented by Formula 1. [71] At this time, the oligomer represented by Formula 1 may be included in 0.5% to 30% by weight, specifically 0.5% to 25% by weight based on the total weight of the electrolyte for a lithium secondary battery. [72] [73] In addition, the electrolyte for a lithium secondary battery of the present invention may be a gel polymer electrolyte including an oligomer-derived polymer represented by Formula 1 above. [74] In this case, the polymer derived from the oligomer represented by Formula 1 may be a matrix polymer formed into a three-dimensional structure by polymerizing the oligomer represented by Formula 1 in the presence of a polymerization initiator. [75] In addition, the oligomer-derived polymer represented by Formula 1 may be included in 0.5% to 30% by weight, specifically 0.5% to 25% by weight, based on the total weight of the electrolyte for a lithium secondary battery. [76] [77] In addition, in an embodiment of the present invention [78] It is possible to provide a lithium secondary battery comprising the electrolyte for a lithium secondary battery of the present invention. [79] In this case, the electrolyte for the lithium secondary battery may be a liquid electrolyte or a gel polymer electrolyte. Effects of the Invention [80] According to the present invention, by including an oligomer having a hydrophilic and hydrophobic functional group or a polymer derived from such an oligomer, the wettability is improved by lowering the surface tension with the electrode surface, and an electrolyte for a lithium secondary battery capable of suppressing side reactions between the electrolyte and the electrode is prepared. can do. In addition, by including this, it is possible to prevent an average voltage drop by suppressing an increase in the interfacial resistance of the electrode, thereby manufacturing a lithium secondary battery with improved charging and discharging efficiency. Best mode for carrying out the invention [81] Hereinafter, the present invention will be described in more detail. [82] 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. [83] Meanwhile, 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. [84] 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. [85] In this specification, "%" means% by weight unless otherwise indicated. [86] In the description of "carbon number a to b" in the present specification, "a" and "b" mean the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "an alkyl group having 1 to 3 carbon atoms" is an alkyl group containing 1 to 3 carbon atoms, that is, -CH 3 , -CH 2 CH 3 , -CH 2 CH 2 CH 3 or -CH 2 (CH 2 ) Means CH 3 . [87] In the present specification, the "arylene group" refers to a functional group in which a hydrogen atom is removed from an aromatic hydrocarbon. In one embodiment, the arylene group includes, but is not limited to, a phenylene group, a biphenylylene group, a terphenylylene group, a naphthylene group, or a phenanthrylene group, each of which is optionally substituted in other embodiments. Can be. [88] In addition, in the present specification, "hetero" means that one functional group contains at least one hetero atom selected from the group consisting of N, 0, S, or P, and the rest is carbon, unless otherwise defined. do. [89] In addition, throughout the present specification, the term "heterocycloalkylene group" means that at least one hetero atom of N, O, S, or P is present in the cyclic compound having 2 to 20 carbon atoms instead of carbon. [90] In addition, in the present specification, "substitution" means that at least one hydrogen bonded to carbon is substituted with an element other than hydrogen unless otherwise defined, for example, substituted with an alkyl group having 1 to 3 carbon atoms Means that. [91] [92] Electrolyte for lithium secondary battery [93] Specifically, in an embodiment of the present invention, a lithium salt; Organic solvent; And it is possible to provide an electrolyte for a lithium secondary battery comprising an oligomer represented by the following Formula 1 or an oligomer derived polymer represented by Formula 1 above. [94] [Formula 1] [95] [96] In Formula 1, [97] R 1 and R 2 are each independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, [98] R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, [99] R 5 is hydrogen or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, [100] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [101] z and x are the number of repeat units, [102] z is an integer from 1 to 10, [103] x is an integer from 1 to 15, [104] n is an integer of 1 to 3. [105] Specifically, the electrolyte for a lithium secondary battery of the present invention may be a liquid electrolyte including a lithium salt, an organic solvent, and an oligomer represented by Chemical Formula 1. [106] In addition, the electrolyte for a lithium secondary battery of the present invention may be a gel polymer electrolyte for a lithium secondary battery including a lithium salt, an organic solvent, and an oligomer-derived polymer represented by Formula 1 above. [107] [108] (1) Liquid electrolyte for lithium secondary batteries [109] An embodiment of the present invention provides an electrolyte for a lithium secondary battery comprising a lithium salt, an organic solvent, and an oligomer represented by Formula 1 above. [110] In this case, the electrolyte for the lithium secondary battery may be a liquid electrolyte. [111] [112] (1-1) lithium salt [113] On the other hand, the lithium salt used in the lithium secondary battery electrolyte of the present invention can be used without limitation, those which are commonly used in a lithium secondary battery electrolyte, such as Li in the lithium salt cationic + anionic, and include the F - , Cl - , Br - , I - , NO 3 - , N (CN) 2 - , BF 4 - , ClO 4 - , AlO 4 - , AlCl 4 - , PF 6 - , SbF 6 - , AsF 6 - , 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 - , CF 3 SO 3 - , 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 3SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3 - , CF 3 CO 2 - , CH 3 CO 2 - , SCN - And (CF 3 CF 2 SO 2 ) 2At least any one selected from the group consisting of N - is mentioned. 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 , and LiCH 3 SO 3It may contain a single substance or a mixture of two or more selected from the group consisting of, and in addition to these, lithium bisperfluoroethanesulfonimide (LiN(SO 2 C 2 F 5 ) 2 ), LiFSI (lithium fluorosulfonyl), which are commonly used in electrolytes of lithium secondary batteries. A lithium salt such as a lithium imide salt represented by imide, LiN(SO 2 F) 2 ), and LiTFSI (lithium (bis)trifluoromethanesulfonimide, LiN(SO 2 CF 3 ) 2 ) can be used without limitation. Specifically, the lithium salt is LiPF 6 , LiBF 4 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiCH 3SO 3 , LiFSI, LiTFSI and LiN(C 2 F 5 SO 2 ) 2 It may include a single substance or a mixture of two or more selected from the group consisting of. [114] The lithium salt may be appropriately changed within a range that is generally usable, but may be specifically contained in the electrolyte in an amount of 0.1 M to 3M, specifically 0.8M to 2.5M. If the concentration of the lithium salt exceeds 3M, the viscosity of the electrolyte may increase, thereby reducing the lithium ion transfer effect. [115] [116] (1-2) organic solvent [117] The organic solvent may include at least one organic solvent selected from the group consisting of a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent. [118] Specifically, the organic solvent may include a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. [119] Specific examples of the cyclic carbonate-based organic solvent include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3- Any one selected from the group consisting of pentylene carbonate and vinylene carbonate, or a mixture of two or more of them, among which, as an organic solvent of high viscosity, includes ethylene carbonate that has a high dielectric constant and thus easily dissociates lithium salts in the electrolyte. I can. [120] 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), methylpropyl carbonate, and may include at least one selected from the group consisting of ethylpropyl carbonate. [121] In addition, the organic solvent may further include a linear ester-based organic solvent and/or a cyclic ester-based organic solvent in order to prepare an electrolyte solution having a high electrical conductivity. [122] Such a linear ester-based organic solvent may 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 as specific examples. have. [123] In addition, the cyclic ester-based organic solvent may include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. . [124] In addition, 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 and a nitrile-based organic solvent. [125] The ether-based organic solvent may include any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methylpropyl ether, and ethylpropyl ether. [126] The nitrile-based organic solvent is, for example, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4 -It may contain any one selected from the group consisting of fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile. . [127] [128] (1-3) Compound represented by Formula 1 [129] The electrolyte for a lithium secondary battery of the present invention may include an oligomer represented by Formula 1 below. [130] [Formula 1] [131] [132] In Formula 1, [133] R 1 and R 2 are each independently a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, [134] R 3 and R 4 are each independently hydrogen or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, [135] R 5 is hydrogen or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, [136] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [137] z and x are the number of repeat units, [138] z is an integer from 1 to 10, [139] x is an integer from 1 to 15, [140] n is an integer of 1 to 3. [141] [142] At this time, in Formula 1, the aliphatic hydrocarbon group of R'is (a) a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms, a substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms, and a substituted or unsubstituted At least one alicyclic hydrocarbon group selected from the group consisting of a heterocycloalkylene group having 2 to 20 carbon atoms and (b) a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxyl having 1 to 20 carbon atoms It may include at least one selected from the group consisting of at least one linear hydrocarbon group selected from the group consisting of a silene group, a substituted or unsubstituted alkenylene group having 2 to 20 carbon atoms, and a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms. have. [143] In addition, the aromatic hydrocarbon group of R′ may include at least one selected from a substituted or unsubstituted arylene group having 6 to 20 carbon atoms and a substituted or unsubstituted heteroarylene group having 2 to 20 carbon atoms. [144] Specifically, in Formula 1, the aliphatic hydrocarbon group of R'is a substituted or unsubstituted cycloalkylene group having 4 to 20 carbon atoms, a substituted or unsubstituted cycloalkenylene group having 4 to 20 carbon atoms, and a substituted or unsubstituted carbon number. It may include at least one alicyclic hydrocarbon group selected from the group consisting of 2 to 20 heterocycloalkylene groups. [145] [146] The oligomer represented by Formula 1 contains an acrylate-based functional group, which is a hydrophilic moiety capable of forming a crosslinking bond by itself at both ends, and a siloxane group (-Si-O-) and a urethane (-NC ( Since it contains O)O-) groups, it can provide a surfactant role in the battery, thereby lowering the interface resistance by balanced affinity with the positive electrode or separator (SRS layer) as a hydrophilic part and the negative electrode or separator fabric as a hydrophobic part. . Therefore, the electrolyte for a lithium secondary battery including the oligomer represented by Formula 1 may have a more improved wettability effect. [147] In addition, the oligomer represented by Formula 1 forms a stable ion conductive film on the surface of the negative electrode during initial charging and suppresses side reactions between the electrolyte and Li metal deposited on the surface of the negative electrode during overcharging, so that the interface between the electrode and the electrolyte for a conventional lithium secondary battery It is possible to suppress an increase in resistance and a change in the average voltage during charge/discharge resulting from this. Accordingly, it is possible to provide a lithium secondary battery with improved charge/discharge efficiency and high rate characteristics. [148] On the other hand, the oligomer represented by Formula 1 of the present invention includes a siloxane group (-[Si-O]-) and a urethane group as a repeating unit of the main chain, and the oligomer does not additionally contain a -Si- group together with a siloxane group in the structure. It is desirable not to. That is, by not including an additional -Si- group as a repeating unit in the oligomer structure, the ratio of the functional groups at both ends can be increased and the molecular weight of the entire polymer can be lowered. Therefore, assuming that the same content in the electrolyte is added, the structure It is possible to increase the content of the total oligomer compared to oligomers that further include -Si- groups (eg, including -[Si-O]-Si- structures as a main chain repeating unit). Therefore, since the reaction rate of the gel polymer can be advantageously obtained, the hardness of the gel polymer can be increased, and the hardness of the entire battery can be strengthened, so that it can act more advantageously in safety evaluation, for example, impact evaluation giving a physical impact. [149] [150] Specifically, the oligomer represented by Formula 1 may be at least one selected from the group consisting of oligomers represented by the following Formulas 1a and 1b. [151] [Formula 1a] [152] [153] In Formula 1a, [154] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [155] z1 and x1 are the number of repeat units, [156] z1 is an integer from 1 to 10, [157] x1 is an integer in any one of 1-15. [158] [159] [Formula 1b] [160] [161] In Formula 1b, [162] R'is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [163] z2 and x2 are the number of repeat units, [164] z2 is an integer from 1 to 10, [165] x2 is an integer in any one of 1-15. [166] [167] More specifically, the oligomer represented by Formula 1 may be any one selected from the group consisting of oligomers represented by Formulas 1a-1 and 1b-1 below. [168] [Formula 1a-1] [169] [170] In Formula 1a-1, [171] z1 and x1 are the number of repeat units, [172] z1 is an integer from 1 to 10, [173] x1 is an integer in any one of 1-15. [174] [175] [Formula 1b-1] [176] [177] In Formula 1b-1, [178] z2 and x2 are the number of repeat units, [179] z2 is an integer from 1 to 10, [180] x2 is an integer in any one of 1-15. [181] [182] The weight average molecular weight (Mw) of the oligomer represented by Formula 1 may be adjusted by the number of repeating units, and about 1,000 g/mol to 100,000 g/mol, specifically 1,000 g/mol to 50,000 g/mol, more Specifically, it may be 1,000 g/mol to 10,000 g/mol. When the weight average molecular weight of the oligomer is within the above range, the electrolyte solution wettability effect may be improved. In addition, since it is easy to substitute various functional groups as needed, various performance improvement effects can be obtained. [183] If the weight average molecular weight of the oligomer is less than 1,000 g/mol, electrochemical stability and the role of surfactant cannot be expected, and the effect of inhibiting side reactions on the electrode surface may be insignificant because the functional group content is low, and the weight average molecular weight is 100,000 g If it exceeds /mol, there is a disadvantage that the solubility in an organic solvent may decrease. [184] The weight average molecular weight may mean a value converted to standard polystyrene measured by gel permeation chromatography (GPC), and unless otherwise specified, the molecular weight may mean a weight average molecular weight. For example, in the present invention, measurements are made using Agilent's 1200 series under GPC conditions, and the used column may be Agilent's PL mixed B column, and THF may be used as a solvent. [185] [186] On the other hand, the oligomer represented by Formula 1 is 0.5% to 30% by weight, specifically 0.5% to 25% by weight, more specifically 0.5% to 10% by weight, more specifically based on the total weight of the lithium secondary battery electrolyte. It may be included in 0.5% to 5% by weight. [187] When the content of the oligomer represented by Formula 1 is 0.5% by weight or more, the effect of controlling reactivity with lithium metal and electrochemical stability can be expected, and when the content of the oligomer represented by Formula 1 is less than 30% by weight, the resistance increase due to the addition of an excessive amount of oligomer is prevented and thus wettability At the same time, it is possible to prevent disadvantages such as a decrease in ionic conductivity by improving the limit of movement of lithium ions. If the content of the oligomer represented by Chemical Formula 1 exceeds 30% by weight, the solubility of the oligomer in the electrolyte solution decreases, and the viscosity of the electrolyte solution increases, so that the ionic conductivity of the electrolyte decreases. As a result, a voltage drop of the battery may be caused due to an increase in the interface resistance of the electrode. [188] [189] (1-4) additional additives [190] In addition, the electrolyte for a lithium secondary battery of the present invention prevents negative electrode collapse due to decomposition of a non-aqueous electrolyte in a high-power environment, or further improves low-temperature high-rate discharge characteristics, high-temperature stability, prevention of overcharging, and swelling improvement during high-temperature storage. To this end, in addition to the compound of Formula 1, additional additives capable of forming a more stable ion conductive film on the electrode surface may be further included. [191] These additional additives may include at least one selected from the group consisting of a sultone-based compound, a halogen-substituted carbonate-based compound, a nitrile-based compound, a cyclic sulfite-based compound, and a cyclic carbonate-based compound. [192] The sultone-based compound is 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1, And at least one compound selected from the group consisting of 3-propene sultone. The sultone-based compound 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 sultone-based compound in the non-aqueous electrolyte exceeds 5% by weight, a thick film is formed due to an excessive amount of additives, thereby increasing resistance and deteriorating output. [193] In addition, 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. [194] 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. [195] 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. [196] In addition, as the cyclic sulfite-based compound, ethylene sulfite, methyl ethylene sulfite, ethyl ethylene sulfite, 4,5-dimethyl ethylene sulfite, 4,5-diethyl ethylene sulfite, propylene sulfite, 4,5 -Dimethyl propylene sulfite, 4,5-diethyl propylene sulfite, 4,6-dimethyl propylene sulfite, 4,6-diethyl propylene sulfite, 1,3-butylene glycol sulfite, etc. are mentioned, It may contain less than 5% by weight based on the total weight of the non-aqueous electrolyte. When the content of the cyclic sulfite-based compound exceeds 5% by weight, a thick film is formed due to an excessive amount of additives, thereby increasing resistance and deteriorating output. [197] In addition, the cyclic carbonate-based compound may include vinylene carbonate (VC) or vinylethylene carbonate, and may be included in an amount of 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 may be deteriorated. [198] More specifically, the additional additive may be a cyclic carbonate-based compound. [199] Two or more of the additional additives may be mixed and used, and may be included in an amount of 20% by weight or less, specifically 0.01% to 20% by weight, preferably 0.1 to 10% by weight based on the total amount of the electrolyte. If 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. [200] [201] (2) Gel polymer electrolyte for lithium secondary batteries [202] In addition, in an embodiment of the present invention [203] It provides an electrolyte for a lithium secondary battery comprising a lithium salt, an organic solvent, and an oligomer-derived polymer represented by Chemical Formula 1. [204] The electrolyte for a lithium secondary battery may be formed by thermally polymerizing a composition for a gel polymer electrolyte including the lithium salt, an organic solvent, an oligomer represented by Formula 1, and a polymerization initiator. [205] Meanwhile, the oligomer-derived polymer represented by Formula 1 may include a matrix polymer formed by crosslinking the oligomer represented by Formula 1 into a three-dimensional structure in the presence of a polymerization initiator. [206] The electrolyte for a lithium secondary battery of the present invention may be a gel electrolyte in the form of a non-aqueous electrolyte in which the lithium salt is dissolved in a matrix polymer formed by crosslinking the oligomer represented by Formula 1 in a three-dimensional structure. [207] [208] On the other hand, the description of the lithium salt and the organic solvent and the type and concentration of the oligomer contained in the composition for a gel polymer electrolyte provided to prepare the electrolyte for a lithium secondary battery of the present invention overlap with the above, so the description Omit it. [209] At this time, the oligomer represented by Formula 1 is 0.5% to 30% by weight, specifically 0.5% to 25% by weight, more specifically 0.5% to 10% by weight, based on the total weight of the gel polymer electrolyte composition. Specifically, it may be included in 0.5% by weight to 5% by weight. [210] When the content of the oligomer represented by Formula 1 is included in the above range, that is, in the range of 0.5% to 30% by weight, a polymer network having excellent mechanical strength can be formed, and thus a secondary battery with improved overall performance can be manufactured. Specifically, if the content of the oligomer represented by Formula 1 is 0.5% by weight or more based on the total weight of the gel polymer electrolyte composition, the polymer matrix by the oligomer can be easily formed, and the mechanical strength of the gel polymer electrolyte can be secured. have. In addition, if the content of the oligomer represented by Formula 1 is 30% by weight or less based on the total weight of the gel polymer electrolyte composition, the resistance increase due to the addition of an excessive amount of oligomer is prevented, and an appropriate viscosity is secured, Wetting properties can be improved, and pre-gel reactions can be prevented. Moreover, by improving the movement limitation of lithium ions, ionic conductivity is secured, and cycle life characteristics can be improved. If the content of the oligomer represented by Formula 1 exceeds 30% by weight, the solubility of the oligomer in the composition for the gel polymer electrolyte decreases, the viscosity of the composition increases and the wettability decreases, and the interface resistance of the electrode increases. May cause a voltage drop. [211] [212] Meanwhile, the oligomer-derived polymer represented by Formula 1 is 0.5% to 30% by weight, specifically 0.5% to 25% by weight, more specifically 0.5% to 10% by weight, based on the total weight of the electrolyte for a lithium secondary battery, More specifically, it may be included in 0.5% to 5% by weight. [213] That is, the oligomer-derived polymer represented by Formula 1 is a matrix polymer in which the oligomer represented by Formula 1 is formed in a three-dimensional structure by a thermal polymerization reaction, and its content is an oligomer represented by Formula 1 included in the composition for a gel polymer electrolyte. It is preferably the same as the content of. . [214] At this time, if the content of the oligomer-derived polymer represented by Formula 1 is 0.5% by weight or more, physical properties such as mechanical strength of the gel polymer electrolyte may be secured. In addition, if it is 30% by weight or less, it is possible to prevent an increase in resistance due to the addition of an excessive amount of oligomer, and to improve the mobility of lithium ions to secure ionic conductivity. If the content of the oligomer-derived polymer represented by Formula 1 exceeds 30% by weight, the ionic conductivity of the electrolyte decreases, and the voltage drop of the battery may be caused due to an increase in interface resistance with the electrode. [215] [216] As described above, in addition, the oligomer-derived polymer represented by Formula 1 forms a stable ion conductive film on the electrode surface during initial charging, and suppresses side reactions between Li metal deposited on the negative electrode surface and the electrolyte during overcharge, and By suppressing the oxidation reaction with and, it is possible to suppress an increase in the interface resistance of the electrode compared to the conventional electrolyte for a lithium secondary battery and a change in the average voltage during charge/discharge resulting from this. [217] In addition, the oligomer-derived polymer represented by Formula 1 has the ability to dissociate lithium salts and thus improves lithium ion mobility, and is particularly electrochemically stable as a repeating unit of the main chain, and Since it contains functional groups such as siloxane groups (-Si-O-) with low reactivity, side reactions of lithium ions (Li + ) and decomposition reactions of lithium salts can be controlled. Generation of gases such as 2 can be reduced. Therefore, it is possible to further improve the stability of the secondary battery by suppressing ignition or the like during overcharging. [218] On the other hand, the oligomer-derived polymer represented by Formula 1 of the present invention includes a siloxane group (-[Si-O]-) and a urethane group as a repeating unit of the main chain, and the oligomer further includes a -Si- group together with a siloxane group in the structure. It is preferable not to include it. That is, by not including an additional -Si- group as a repeating unit in the oligomer structure, the ratio of the functional groups at both ends can be increased and the molecular weight of the entire polymer can be lowered. Therefore, assuming that the same content in the electrolyte is added, the structure It is possible to increase the content of the total oligomer compared to oligomers that further include -Si- groups (eg, including -[Si-O]-Si- structures as a main chain repeating unit). Therefore, since the reaction rate of the gel polymer can be advantageously obtained, the hardness of the gel polymer can be increased, and the hardness of the entire battery can be strengthened, so that it can act more advantageously in safety evaluation, for example, impact evaluation giving a physical impact. [219] [220] (2-1) polymerization initiator [221] Meanwhile, the polymerization initiator used to prepare the gel polymer electrolyte may be a conventional polymerization initiator known in the art. For example, the polymerization initiator may be decomposed by heat to form a radical, and reacted with an oligomer represented by Formula 1 by free radical polymerization to form a gel polymer electrolyte. [222] Specifically, the polymerization initiator may be an azo-based polymerization initiator or a peroxide-based polymerization initiator, and representative examples thereof include benzoyl peroxide, acetyl peroxide, dilauryl peroxide, Di-tert-butyl peroxide, t-butyl peroxy-2-ethyl-hexanoate, cumyl hydroperoxide And at least one peroxide-based compound selected from the group consisting of hydrogen peroxide, or 2,2'-azobis (2-cyanobutane), dimethyl 2,2'-azobis (2-methyl Propionate), 2,2'-azobis (methylbutyronitrile), 2,2'-azobis (isobutyronitrile) (AIBN; 2,2'-Azobis (iso-butyronitrile)) and 2, At least one azo-based compound selected from the group consisting of 2'-azobisdimethyl-valeronitrile (AMVN; 2,2'-Azobisdimethyl-valeronitrile) may be mentioned. [223] The polymerization initiator is decomposed by heat in the secondary battery, non-limiting example, by heat of 30°C to 100°C, specifically 60°C to 80°C, or decomposed at room temperature (5°C to 30°C) to form radicals, and free radicals By polymerization, a polymerizable oligomer can react with an acrylate compound to form a gel polymer electrolyte. [224] [225] The polymerization initiator may be included in an amount of about 0.01 parts by weight to about 20 parts by weight, specifically 5 parts by weight based on the total 100 parts by weight of the oligomer, and when included in the above range, the gelation reaction is easily performed to increase the gel polymer conversion rate. Gel polymer electrolyte properties can be secured, unreacted polymerization initiators remaining after polymerization can be prevented from causing side reactions, and wetting properties of an electrolyte solution to an electrode can be improved. [226] In particular, in the case of some polymerization initiators, nitrogen or oxygen gas may be generated in the process of generating radicals due to heat or the like. In most cases, such gas generation leads to gas trapping or gas bubbling during the formation of the gel polymer electrolyte. In the case of generation of such gas, the quality of the electrolyte is deteriorated because it causes defects in the gel polymer electrolyte. Accordingly, when the polymerization initiator is included in the above range, it is possible to more effectively prevent disadvantages such as generation of a large amount of gas. [227] [228] Secondary battery [229] In addition, in an embodiment of the present invention [230] It is possible to provide a lithium secondary battery comprising a negative electrode, a positive electrode, a separator interposed between the negative electrode and the positive electrode, and the electrolyte for a lithium secondary battery of the present invention. [231] The electrolyte for a lithium secondary battery may be a liquid electrolyte or a gel polymer electrolyte. [232] When the electrolyte for a lithium secondary battery is a liquid electrolyte, the lithium secondary battery of the present invention stores an electrode assembly formed by sequentially stacking a positive electrode, a negative electrode, and a separator selectively interposed between the positive electrode and the negative electrode in a secondary battery case or exterior material. , It can be prepared by injecting the electrolyte for a lithium secondary battery of the present invention. [233] [234] In addition, when the electrolyte for a lithium secondary battery is a gel polymer electrolyte including a polymer matrix formed by polymerization between oligomers represented by Formula 1, the lithium secondary battery of the present invention selectively comprises a positive electrode, a negative electrode, and a positive electrode and a negative electrode. The electrode assembly formed by sequentially stacking the interposed separators may be accommodated in a secondary battery case or an exterior material, and then the electrolyte composition for a lithium secondary battery is injected and then cured. [235] For example, it may be formed by performing an in-situ polymerization reaction in which an electrolyte for a lithium secondary battery is injected inside the secondary battery . The in-situ polymerization reaction may be performed through an electron beam (E-BEAM), gamma ray, room temperature or high temperature aging process, and according to an embodiment of the present invention may be performed through thermal polymerization. In this case, the polymerization time may take about 2 minutes to 48 hours, and the thermal polymerization temperature may be 60°C to 100°C, specifically 60°C to 80°C. [236] [237] On the other hand, in the lithium secondary battery of the present invention, the positive electrode, the negative electrode, and the separator may be all those that have been manufactured and used by a conventional method when manufacturing a lithium secondary battery. [238] (1) anode [239] First, the positive electrode may be manufactured by forming a positive electrode mixture layer on a 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. [240] 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. [241] 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-based oxide (eg, LiMnO 2 , LiMn 2 O 4, etc.), a lithium-cobalt-based oxide (eg, LiCoO 2, etc.), and a lithium-nickel-based oxide (E.g., LiNiO 2 ), lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O 2 (here, 0