[0001]This application claims priority from Korean Patent Application No. 10-2019-0108783, filed on September 3, 2019, 10 the disclosure of which is incorporated by reference herein. Technical Field [0002] The present invention relates to a non-aqueous electrolyte solution and a lithium secondary battery including the same, and more particularly, to a non-aqueous electrolyte 15 solution, which may improve rapid charging performance and resistance characteristics of a secondary battery, and a lithium secondary battery including the same. BACKGROUND ART [0003] A lithium secondary battery is generally prepared by 20 a method in which, after an electrode assembly is formed by disposing a separator between a positive electrode, which includes a positive electrode active material formed of a transition metal oxide containing lithium, and a negative electrode including a negative electrode active material 25 capable of storing lithium ions and the electrode assembly is 1 PCT/KR2020/011462 inserted into a battery case, a non-aqueous electrolyte solution that becomes a medium for transferring the lithium ions is injected thereinto and the battery case is then sealed. [0004] The lithium secondary batteries have not only been 5 used in portable electronic devices such as mobile phones or notebook computers, but have also been used in electric vehicles, and their demand is increasing rapidly. As the demand for lithium secondary batteries increases and application targets are diversified, a performance level 10 required for lithium secondary batteries is gradually increasing. For example, lithium secondary batteries used in electric vehicles require high energy density, high power characteristics, and durability in which the lithium secondary batteries may be used for a long time under severe conditions. 15 In addition, recently, there is an increasing demand for rapid charging performance capable of charging a battery within a short time. [0005] However, lithium secondary batteries developed to date have insufficient rapid charging performance, and, even when 20 rapid charging is possible, there is a limitation in that battery performance is rapidly degraded when the rapid charging is repeated. DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM 25 [0006] An aspect of the present invention provides a non- 2 PCT/KR2020/011462 aqueous electrolyte solution, which may improve rapid charging performance and resistance characteristics of a lithium secondary battery, and a lithium secondary battery including the same. 5 TECHNICAL SOLUTION [0007] According to an aspect of the present invention, there is provided a non-aqueous electrolyte solution which includes an organic solvent containing cyclic carbonate, dimethyl carbonate, and alkyl formate; a lithium salt; and an oligomer 10 represented by [Formula 1] as a surfactant. [0008] [Formula 1] [0009] In [Formula 1], Rf is an alkylene group having 1 to 5 15 carbon atoms which is unsubstituted or substituted with at least one fluorine, Rg, Rh, Ri, and Rj are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine, R0 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, 20 R’’’ is hydrogen or an alkyl group having 1 to 3 carbon atoms, o is an integer of 1 to 3, and p and q are the numbers of repeating units, wherein p is an integer of 1 to 10, and q is an integer of 1 to 15. 3 PCT/KR2020/011462 [0010] According to another aspect of the present invention, there is provided a lithium secondary battery which includes a positive electrode including a positive electrode active 5 material; a negative electrode including a negative electrode active material; a separator disposed between the negative electrode and the positive electrode; and the non-aqueous electrolyte solution according to the present invention. ADVANTAGEOUS EFFECTS 10 [0011] If a non-aqueous electrolyte solution of the present invention, which includes an organic solvent containing cyclic carbonate, dimethyl carbonate, and alkyl formate, a lithium salt, and an oligomer having a specific structure as a surfactant, is used, a lithium secondary battery having 15 excellent rapid charging performance and low initial resistance characteristics may be achieved. MODE FOR CARRYING OUT THE INVENTION [0012] A non-aqueous electrolyte solution according to the present invention includes (1) an organic solvent containing 20 cyclic carbonate, dimethyl carbonate, and alkyl formate, (2) a lithium salt, and (3) a surfactant. Also, the non-aqueous electrolyte solution of the present invention may further include (4) an additive, if necessary. [0013] Hereinafter, each component of the non-aqueous 25 electrolyte solution of the present invention will be described. 4 PCT/KR2020/011462 [0014] (1) Organic Solvent [0015] The non-aqueous electrolyte solution of the present invention includes cyclic carbonate, dimethyl carbonate, and 5 alkyl formate, as an organic solvent. [0016] The cyclic carbonate is an organic solvent which may well dissociate a lithium salt in the electrolyte solution due to high permittivity as a highly viscous organic solvent, 10 wherein, for example, the cyclic carbonate may include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. Among them, ethylene 15 carbonate capable of maintaining passivation ability of a stable solid electrolyte interface (SEI) is particularly preferred. [0017] The cyclic carbonate may be included in an amount of 10 vol% to 30 vol%, for example, 15 vol% to 25 vol% based on 20 a total volume of the organic solvent. If the cyclic carbonate is included in an amount of less than 10 vol%, since the SEI is unstable, the passivation ability may not be stably maintained, and, if the cyclic carbonate is included in an amount of greater than 30 vol%, viscosity of the electrolyte 25 solution may increase. 5 PCT/KR2020/011462 [0018] Next, the dimethyl carbonate and the alkyl formate are components for improving rapid charging performance, wherein, since the dimethyl carbonate and alkyl formate have relatively 5 low viscosity and high permittivity, an effect of improving ionic conductivity and lithium ion mobility of the electrolyte solution may be obtained when the dimethyl carbonate and alkyl formate are used. 10 [0019] The dimethyl carbonate may be included in an amount of 40 vol% to 85 vol%, for example, 50 vol% to 80 vol% based on the total volume of the organic solvent. If the dimethyl carbonate is included in an amount of less than 40 vol%, the ionic conductivity and lithium ion mobility of the electrolyte 15 solution may be reduced, and, if the dimethyl carbonate is included in an amount of greater than 85 vol%, a side reaction due to reduction decomposition of the dimethyl carbonate may occur. 20 [0020] The alkyl formate, for example, may be an alkyl formate having 1 to 5 carbon atoms, and, for example, may include at least one selected from the group consisting of methyl formate, ethyl formate, propyl formate, n-butyl formate, and iso-butyl formate. 25 [0021] The alkyl formate may be included in an amount of 5 6 PCT/KR2020/011462 vol% to 30 vol%, for example, 5 vol% to 20 vol% based on the total volume of the organic solvent. If the alkyl formate is included in an amount of less than 5 vol%, an effect of improving the rapid charging performance is insignificant, and, 5 if the alkyl formate is included in an amount of greater than 30 vol%, a side reaction due to reduction decomposition of the alkyl formate may occur. [0022] (2) Lithium Salt 10 [0023] Various lithium salts typically used in an electrolyte solution for a lithium secondary battery may be used as the lithium salt used in the present invention without limitation. For example, the lithium salt may include Li+ as a cation, and may include at least one selected from the group consisting of 15 F-, Cl-, Br-, I-, NO3-, N(CN)2-, BF4-, ClO4-, AlO4-, AlCl4-, PF6-, SbF6-, AsF6-, B10Cl10-, BF2C2O4-, BC4O8-, PF4C2O4-, PF2C4O8-, (CF3)2PF4-, (CF3)3PF3-, (CF3)4PF2-, (CF3)5PF-, (CF3)6P-, CF3SO3-, C4F9SO3-, CF3CF2SO3-, (CF3SO2)2N-, (FSO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, CH3SO3-, CF3(CF2)7SO3-, CF3CO2-, CH3CO2-, SCN-, and (CF3CF2SO2)2N- 20 as an anion. [0024] Specifically, the lithium salt may include at least one selected from the group consisting of LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB10Cl10, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI 25 (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI 7 PCT/KR2020/011462 (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include a single material selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI (LiN(SO2F)2) and LiBETI (LiN(SO2CF2CF3)2, 5 or a mixture of two or more thereof. [0025] The lithium salt may be included in a concentration of 0.8 M to 4 M, for example, 1.5 M to 3 M in the electrolyte solution. When the concentration of the lithium salt satisfies 10 the above range, output characteristics of the battery may be improved by improving a lithium ion yield (Li+ transference number) and a degree of dissociation of the lithium ions. [0026] (3) Surfactant 15 [0027] The non-aqueous electrolyte solution according to the present invention includes an oligomer represented by [Formula 1] as a surfactant. [0028] [Formula 1] [0029] In [Formula 1], Rf is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with at least one fluorine, and is preferably a fluorine-substituted 8 PCT/KR2020/011462 alkylene group having 1 to 5 carbon atoms. [0030] Rg, Rh, Ri, and Rj are each independently a fluorine element or an alkyl group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine, and preferably are 5 each independently a fluorine element or a fluorine- substituted alkyl group having 1 to 3 carbon atoms. [0031] R0 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Specifically, the aliphatic hydrocarbon group, for example, may include at least one selected from the 10 group consisting of (a) at least one alicyclic hydrocarbon group selected from the group consisting of 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 15 heterocycloalkylene group having 2 to 20 carbon atoms, and (b) at least one linear hydrocarbon group selected from the group consisting of a substituted or unsubstituted alkylene group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxylene group having 1 to 20 carbon atoms, a substituted or 20 unsubstituted alkenylene group having 2 to 20 carbon atoms, and a substituted or unsubstituted alkynylene group having 2 to 20 carbon atoms. Also, the aromatic hydrocarbon group may include at least one selected from the group consisting of a substituted or unsubstituted arylene group having 6 to 20 25 carbon atoms and a substituted or unsubstituted heteroarylene 9 PCT/KR2020/011462 group having 2 to 20 carbon atoms. [0032] R’’’ is hydrogen or an alkyl group having 1 to 3 carbon atoms. [0033] o is an integer of 1 to 3, and p and q are the numbers 5 of repeating units, wherein p is an integer of 1 to 10, and q is an integer of 1 to 15. [0034] Since the oligomer represented by [Formula 1] contains a fluorine-substituted ethylene group, as a hydrophobic part, 10 as well as an acrylate-based functional group, as a hydrophilic group, at both ends, the oligomer represented by [Formula 1] may act as a surfactant to obtain an effect of reducing surface resistance between the electrolyte solution and an electrode interface and improving wetting of the battery. 15 [0035] Preferably, the surfactant may be an oligomer represented by Formula 1-1 below. [0036] [Formula 1-1] 10 PCT/KR2020/011462 [0037] In Formula 1-1, p1 and q1 are the numbers of repeating units, wherein p1 is an integer of 1 to 10, and q1 is an integer of 1 to 15. 5 [0038] A weight-average molecular weight (Mw) of the oligomer represented by Formula 1 may be controlled by the number of repeating units, and may be in a range of about 1,000 g/mol to about 100,000 g/mol, particularly 1,000 g/mol to 50,000 g/mol, 10 and more particularly 1,000 g/mol to 10,000 g/mol. When the weight-average molecular weight of the oligomer satisfies the above range, since affinity with the electrolyte solution is high, the oligomer may be well dissolved in the electrolyte solution. The weight-average molecular weight may denote a 15 standard polystyrene-equivalent value measured by gel permeation chromatography (GPC), and, unless otherwise specified, a molecular weight may denote the weight-average molecular weight. For example, in the present invention, the GPC conditions are as follows: the weight-average molecular 11 PCT/KR2020/011462 weight is measured by using 1200 series by Agilent Technologies, a PL mixed B column by Agilent Technologies may be used in this case, and tetrahydrofuran (THF) may be used as a solvent. 5 [0039] The surfactant may be included in an amount of 0.01 wt% to 5 wt%, preferably 0.1 wt% to 3 wt%, and more preferably 0.1 wt% to 1 wt% based on the total weight of the non-aqueous electrolyte solution. When the amount of the surfactant satisfies the above range, an effect of improving the wetting 10 of the battery may be obtained. If the amount of the surfactant is excessively small, the effect of improving the wetting may be insignificant, and, if the amount of the surfactant is excessively large, resistance may be increased and ionic conductivity may be reduced because the surfactant 15 acts as an impurity. [0040] (4) Additive [0041] Although not essential, in order to prevent the electrolyte solution from being decomposed to cause collapse 20 of a negative electrode in a high output environment, or further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge protection, and a battery swelling suppression effect at high temperatures, the electrolyte solution according to the 25 present invention may further include additives. 12 PCT/KR2020/011462 [0042] Examples of the additive may be at least one selected from the group consisting of a cyclic carbonate-based compound, a halogen-substituted carbonate-based compound, a sultone- based compound, a sulfate-based compound, a phosphate-based 5 compound, a borate-based compound, a nitrile-based compound, a benzene-based compound, an amine-based compound, a silane-based compound, and a lithium salt-based compound. [0043] The cyclic carbonate-based compound, for example, may include vinylene carbonate (VC) or vinyl ethylene carbonate. 10 [0044] The halogen-substituted carbonate-based compound, for example, may include fluoroethylene carbonate (FEC). [0045] The sultone-based compound, for example, may include at least one compound selected from the group consisting of 1,3-propane sultone (PS), 1,4-butane sultone, ethane sultone, 15 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl- 1,3-propene sultone. [0046] The sulfate-based compound, for example, may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS). 20 [0047] The phosphate-based compound, for example, may include at least one compound selected from the group consisting of lithium difluoro bis(oxalato)phosphate, lithium difluorophosphate, tetramethyl trimethylsilyl phosphate, trimethylsilyl phosphite, tris(2,2,2-trifluoroethyl)phosphate, 25 and tris(trifluoroethyl)phosphite. 13 PCT/KR2020/011462 [0048] The borate-based compound, for example, may include tetraphenylborate and lithium oxalyldifluoroborate. [0049] The nitrile-based compound, for example, may include at least one compound selected from the group consisting of 5 succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2- fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, 10 phenylacetonitrile, 2-fluorophenylacetonitrile, and 4- fluorophenylacetonitrile. [0050] The benzene-based compound, for example, may include fluorobenzene, the amine-based compound may include triethanolamine or ethylenediamine, and the silane-based 15 compound may include tetravinylsilane. [0051] The lithium salt-based compound is a compound different from the lithium salt included in the non-aqueous electrolyte solution, wherein the lithium salt-based compound may include at least one compound selected from the group 20 consisting of LiPO2F2, LiODFB, LiBOB (lithium bis(oxalato)borate (LiB(C2O4)2)), and LiBF4. [0052] The additives may be used alone or may be used as a mixture of two or more thereof. 25 [0053] Preferably, as the additive, the non-aqueous 14 PCT/KR2020/011462 electrolyte solution of the present invention may include at least one selected from the group consisting of a cyclic carbonate-based compound, a sultone-based compound, a sulfate- based compound, a lithium salt-based compound, and a benzene- 5 based compound, and may more preferably include a cyclic carbonate-based compound, a sultone-based compound, a sulfate- based compound, a lithium salt-based compound, and a benzene- based compound. More preferably, the non-aqueous additive of the present invention may include vinylene carbonate, 1,3- 10 propane sultone, ethylene sulfate, LiBF4, and fluorobenzene. [0054] In a case in which a combination of the additives is included, a stable film may be formed on a positive electrode and a negative electrode at the same time. In this case, since decomposition of the electrolyte may not only be suppressed by 15 the film formed on the negative electrode even under high- temperature and high-pressure conditions, but dissolution of transition metal contained in the positive electrode may also be suppressed by the film formed on the positive electrode, high-temperature and high-pressure properties and stability of 20 the battery may be improved. [0055] A total amount of the additives may be in a range of 1 wt% to 15 wt%, preferably 1 wt% to 12 wt%, and more preferably 1 wt% to 11 wt% based on the total weight of the electrolyte 25 solution. In a case in which the additives are included in an 15 PCT/KR2020/011462 amount with the above range, occurrence of a side reaction during an initial activation process of the secondary battery or remaining or precipitation of the additive may be prevented while a film is stably formed on the electrode and an ignition 5 phenomenon during overcharge may be suppressed. [0056] Lithium Secondary Battery [0057] Next, a lithium secondary battery according to the present invention will be described. 10 [0058] The lithium secondary battery according to the present invention includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte solution, and, in this case, the non-aqueous electrolyte solution is the 15 non-aqueous electrolyte solution according to the present invention. Since the non-aqueous electrolyte solution has been described above, a description thereof will be omitted and other components will be described below. 20 [0059] (1) Positive Electrode [0060] The positive electrode according to the present invention may include a positive electrode active material layer including a positive electrode active material, and, if necessary, the positive electrode active material layer may 25 further include a conductive agent and/or a binder. 16 PCT/KR2020/011462 [0061] The positive electrode active material is a compound capable of reversibly intercalating and deintercalating lithium, wherein the positive electrode active material may 5 specifically include a lithium composite metal oxide including lithium and at least one transition metal such as cobalt, manganese, nickel, or aluminum. Specifically, the lithium composite metal oxide may include lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), lithium-cobalt-based oxide 10 (e.g., LiCoO2, etc.), lithium-nickel-based oxide (e.g., LiNiO2, etc.), lithium-nickel-manganese-based oxide (e.g., LiNi1-YMnYO2 (where 0