0001] This application claims the benefit of Korean Patent Application Nos. 2018-0065518, filed on June 7, 2018, and 10 2019-0066923, filed on June 5, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field [0002] The present invention relates to a lithium secondary 15 battery having improved low-temperature resistance characteristics and improved storage characteristics, life characteristics, and capacity characteristics at high temperature. BACKGROUND ART 20 [0003] There is a need to develop technology for efficiently storing and utilizing electrical energy as personal IT devices and computer networks are developed with the development of information society and the accompanying dependency of society as a whole on the electrical energy is 25 increased. 2 [0004] Among the technologies developed for this purpose, a technology based on secondary batteries is the most suitable technology for various applications. Since a secondary battery may be miniaturized to be applicable to a personal IT 5 device and may be applied to an electric vehicle and a power storage device, there emerges an interest in the secondary battery. Among these secondary battery technologies, lithium ion batteries, which are battery systems having the theoretically highest energy density, are in the spotlight, 10 and are currently being used in various devices. [0005] Unlike the early days when lithium metal was directly used in an electrode, the lithium ion battery has been realized as a system in which a transition metal oxide material containing lithium is used as a positive electrode 15 material, and a carbon-based material, such as graphite, and an alloy-based material, such as silicon, are used as a negative electrode material [0006] The lithium ion battery is substantially composed of four materials such as a positive electrode formed of a 20 transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte solution as a medium for transferring lithium ions, and a separator. [0007] In line with the recent demand for secondary batteries with high capacity/high energy density, there is a 25 need to develop a secondary battery in which life 3 characteristics and capacity characteristics are improved by improving an increase in resistance and a decrease in capacity during storage or charge and discharge at high temperature and preventing electrochemical decomposition at 5 an electrode interface while maximizing energy storage capacity. [0008] Prior Art Document [0009] Japanese Patent Application Laid-open Publication No. 10 2005-276844 [0010] Japanese Patent Application Laid-open Publication No. 2003-197264 DISCLOSURE OF THE INVENTION TECHNICAL PROBLEM 15 [0011] An aspect of the present invention provides a lithium secondary battery in which low-temperature resistance characteristics are improved and degradation of charge and discharge characteristics at high temperature and life characteristics and capacity characteristics even after high20 temperature storage may be prevented by including a positive electrode containing a highly loaded positive electrode material mixture layer and a non-aqueous electrolyte solution containing a high concentration lithium salt. TECHNICAL SOLUTION 25 [0012] According to an aspect of the present invention, 4 there is provided a lithium secondary battery including: [0013] a positive electrode including a positive electrode material mixture layer formed on a positive electrode collector; 5 [0014] a negative electrode including a negative electrode material mixture layer formed on a negative electrode collector; [0015] a separator disposed between the positive electrode and the negative electrode; and 10 [0016] a non-aqueous electrolyte solution including a lithium salt, an organic solvent, and a compound represented by Formula 1 as a first additive, [0017] wherein the positive electrode material mixture layer has a loading capacity of 3.7 mAh/cm2 to 10 mAh/cm2, 15 [0018] the lithium salt has a concentration of 1.5 M to 3 M, [0019] the organic solvent is a mixed solvent including a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, and [0020] the compound represented by Formula 1 is included in 20 an amount of 0.1 wt% to 5 wt% based on a total weight of the non-aqueous electrolyte solution: [0021] [Formula 1] 5 [0022] wherein, in Formula 1, [0023] R1 is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with fluorine, or -R1’- O-, wherein R1’ is an alkylene group having 1 to 5 carbon 5 atoms which is unsubstituted or substituted with fluorine, [0024] R2 is an alkylene group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine, or –R2’- O-, wherein R2’ is an alkylene group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine, 10 [0025] R3 is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with fluorine, [0026] R4 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, [0027] Ra and Rb are each independently hydrogen or an alkyl 15 group having 1 to 3 carbon atoms, [0028] o, p, q, and r are the numbers of repeating units, [0029] o is an integer of 1 to 5, [0030] p is an integer of 1 to 10, [0031] r is an integer of 1 to 5, 20 [0032] q is an integer of 1 to 15, and [0033] b and c are each independently an integer of 1 to 3. [0034] In the lithium secondary battery of the present invention, the positive electrode material mixture layer may 25 have a loading capacity of 4 mAh/cm2 to 8 mAh/cm2, for 6 example, 4 mAh/cm2 to 6 mAh/cm2. [0035] Also, in the lithium secondary battery of the present invention, the non-aqueous electrolyte solution may include a lithium salt having a concentration of 2 M to 2.5 M. 5 [0036] The organic solvent in the non-aqueous electrolyte solution is a mixed solvent including a cyclic carbonatebased organic solvent and a linear carbonate-based organic solvent, wherein the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be 10 included in a volume ratio of 0.5:9.5 to 2:8. [0037] Furthermore, in the compound represented by Formula 1 as the first additive included in the non-aqueous electrolyte solution, R1 may be -R1’-O-, wherein R1’ is an alkylene group having 1 to 5 carbon atoms which is substituted with fluorine, 15 R2 may be –R2’-O-, wherein R2’ is an alkylene group having 1 to 3 carbon atoms which is substituted with fluorine, and R3 may be an alkylene group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine. [0038] Specifically, the compound represented by Formula 1, 20 as the first additive, may be a compound represented by Formula 1a below. [0039] [Formula 1a] 7 [0040] In Formula 1a, [0041] p1 and q1 are the numbers of repeating units, [0042] p1 is an integer of 1 to 10, and 5 [0043] q1 is an integer of 1 to 5. [0044] The first additive may be included in an amount of 0.1 wt% to 3 wt%, for example, 0.1 wt% to 1 wt% based on the total weight of the non-aqueous electrolyte solution. 10 [0045] The lithium secondary battery may have a capacity retention of 82% or more after the lithium secondary battery is charged at a rate of 0.33 C to 4.25 V under a constant current-constant voltage (CC-CV) condition, stored at 60°C 15 for 6 weeks, and discharged at a rate of 0.33 C to 2.5 V under a CC condition. [0046] Also, the lithium secondary battery may have a capacity retention of 83% or more which is measured after 150 cycles are performed in which charging at a rate of 0.33 C to 20 4.25 V under a CC-CV condition at a high temperature (45°C) and discharging at a rate of 0.1 C to 2.5 V under a CC 8 condition are set as one cycle. ADVANTAGEOUS EFFECTS [0047] A lithium secondary battery of the present invention may secure high capacity by including a positive electrode 5 containing a highly loaded positive electrode material mixture layer with a loading capacity of 3.7 mAh/cm2 or more. Also, the lithium secondary battery of the present invention may improve an effect of the movement of lithium ions and wetting of a non-aqueous electrolyte solution to the 10 electrode by including the non-aqueous electrolyte solution containing a high concentration lithium salt and an acrylatebased compound having a specific structure as an additive, and, since decomposition of a solvent at high temperature and the resulting side reaction may be prevented by reducing an 15 amount of free solvent due to coordination bonds between the organic solvent and Li+ in the battery, storage characteristics, life characteristics, and capacity characteristics after storage or charge and discharge at high temperature as well as low-temperature resistance 20 characteristics may be improved. BRIEF DESCRIPTION OF THE DRAWINGS [0048] The following drawings attached to the specification illustrate preferred examples of the present invention by example, and serve to enable technical concepts of the 25 present invention to be further understood together with 9 detailed description of the invention given below, and therefore the present invention should not be interpreted only with matters in such drawings. [0049] FIG. 1 is a graph illustrating the results of 2C 5 discharge capacity evaluation of lithium secondary batteries according to Experimental Example 2 of the present invention. MODE FOR CARRYING OUT THE INVENTION [0050] Hereinafter, the present invention will be described in more detail. 10 [0051] It will be understood that words or terms used in the specification and claims shall not be interpreted as the meaning defined in commonly used dictionaries. It will be further understood that the words or terms should be interpreted as having a meaning that is consistent with their 15 meaning in the context of the relevant art and the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words or terms to best explain the invention. [0052] For example, in this specification, it will be 20 further understood that the terms “include,” “comprise,” or "have" specify the presence of stated features, numbers, steps, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, elements, or combinations thereof. 25 [0053] Also, the expressions “a” and “b” in the description 10 of “a to b carbon atoms” in the specification each denote 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, the expression “alkylene group 5 having 1 to 5 carbon atoms” denotes an alkylene group including 1 to 5 carbon atoms, that is, -CH2-, -CH2CH2-, - CH2CH2CH2-, -CH2(CH2)CH-, -CH2CH2CH2CH2CH2-, and -CH(CH2)CH2CH2-. [0054] Furthermore, in this specification, the expression “alkylene group” denotes a branched or unbranched aliphatic 10 hydrocarbon group or a functional group in the form in which one hydrogen atom is removed from a carbon atom located at both ends of the aliphatic hydrocarbon group. In an embodiment, the alkylene group may be substituted or unsubstituted. The alkylene group may include a methylene 15 group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a tertbutylene group, a pentylene group, and a 3-pentylene group, but the alkylene group is not limited thereto, and each of which may be optionally substituted in other embodiments. 20 [0055] Also, unless otherwise defined in the specification, the expression “substitution” denotes that at least one hydrogen bonded to carbon is substituted with another element such as fluorine. [0056] Furthermore, a unit of “loading capacity” in this 25 specification is mAh/cm2. 11 [0057] That is, the loading capacity denotes a discharge capacity per unit area which is measured using a half-cell that includes a positive electrode including a positive electrode active material. Specifically, after a half-cell 5 is prepared by using a positive electrode active material such as Li(Ni0.6Mn0.2Co0.2)O2 or Li(Ni0.8Mn0.1Co0.1)O2, the loading capacity may be calculated by substituting discharge capacity, which is obtained by charging the half-cell at a rate of 0.1 C to 4.25 V at 25°C under a constant current-constant voltage 10 (CC-CV) condition and discharging the half-cell at a rate of 0.1 C to 2.5 V under a CC condition, into the following Equation. [0058] [Equation] Loading capacity (mAh/cm2) = [discharge capacity × true density of positive electrode active 15 material] × thickness of positive electrode active material layer [0059] As a result of significant amount of research conducted to improve overall performance after high20 temperature storage of a lithium secondary battery, the present inventors have found that, in a case in which a positive electrode containing a highly loaded positive electrode material mixture layer and a non-aqueous electrolyte solution containing a high concentration lithium 25 salt and a specific additive are included, high capacity may 12 be secured, an effect of the movement of lithium ions may be improved, wetting of the non-aqueous electrolyte solution to the electrode may be simultaneously improved, and a performance degradation caused by decomposition of a solvent 5 at high temperature and the resulting side reaction may be improved by reducing an amount of free solvent due to coordination bonds between the solvent and Li+ in the battery, thereby leading to the completion of the present invention. 10 [0060] Lithium Secondary Battery [0061] Hereinafter, a lithium secondary battery according to the present invention will be described in more detail. [0062] The lithium secondary battery according to an embodiment of the present invention includes: 15 [0063] a positive electrode including a positive electrode material mixture layer formed on a positive electrode collector; [0064] a negative electrode including a negative electrode material mixture layer formed on a negative electrode 20 collector; [0065] a separator disposed between the positive electrode and the negative electrode; and [0066] a non-aqueous electrolyte solution including a lithium salt, an organic solvent, and a compound represented 25 by the following Formula 1 as a first additive, 13 [0067] wherein the positive electrode material mixture layer has a loading capacity of 3.7 mAh/cm2 to 10 mAh/cm2, [0068] the lithium salt has a concentration of 1.5 M to 3 M, [0069] the organic solvent is a mixed solvent including a 5 cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, and [0070] the compound represented by Formula 1 may be included in an amount of 0.1 wt% to 5 wt% based on a total weight of the non-aqueous electrolyte solution. 10 [0071] [Formula 1] [0072] In Formula 1, [0073] R1 is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with fluorine, or -R1’- 15 O-, wherein R1’ is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with fluorine, [0074] R2 is an alkylene group having 1 to 3 carbon atoms which is unsubstituted or substituted with fluorine, or –R2’- O-, wherein R2’ is an alkylene group having 1 to 3 carbon 20 atoms which is unsubstituted or substituted with fluorine, [0075] R3 is an alkylene group having 1 to 5 carbon atoms which is unsubstituted or substituted with fluorine, [0076] R4 is an aliphatic hydrocarbon group or an aromatic 14 hydrocarbon group, [0077] Ra and Rb are each independently hydrogen or an alkyl group having 1 to 3 carbon atoms, [0078] o, p, q, and r are the numbers of repeating units, 5 [0079] o is an integer of 1 to 5, [0080] p is an integer of 1 to 10, [0081] r is an integer of 1 to 5, [0082] q is an integer of 1 to 15, and [0083] b and c are each independently an integer of 1 to 3. 10 [0084] In this case, the lithium secondary battery according to the present invention may be a high-voltage lithium secondary battery which is operated at a high voltage of 4.2 V or more. 15 [0085] That is, the lithium secondary battery including the positive electrode and the non-aqueous electrolyte solution of the present invention exhibits excellent thermal stability when stored at room temperature and high temperature after charged at a high voltage of 4.2 V or more. Specifically, 20 the lithium secondary battery may have a capacity retention of 80% or more and a resistance increase rate of 16% or less even after it is charged at a voltage of 4.2 V or more and then stored at 60°C for 6 weeks or more, and may have a capacity retention of 85% or more even after it is charged at 25 a voltage of 2.5 V to 4.2 V or more and then subjected to 150 15 cycles. [0086] (1) Positive Electrode [0087] First, in the lithium secondary battery according to 5 the embodiment of the present invention, the positive electrode may be prepared by a conventional method and used. [0088] That is, the positive electrode includes a positive electrode collector and a positive electrode material mixture layer formed on the positive electrode collector, and, in 10 this case, the positive electrode material mixture layer may be prepared by coating the positive electrode collector with a positive electrode slurry including a positive electrode active material as well as selectively a binder, a conductive agent, and a solvent, and then drying and rolling the coated 15 positive electrode collector. [0089] In this case, it is desirable that the positive electrode material mixture layer formed on the positive electrode collector is formed to have a loading capacity of 3.7 mAh/cm2 or more in order to prepare a positive electrode 20 in which high capacity per unit area is secured. Specifically, the loading capacity of the positive electrode material mixture layer may be in a range of 3.7 mAh/cm2 to 10 mAh/cm2, particularly 4 mAh/cm2 to 8 mAh/cm2, and more particularly 4 mAh/cm2 to 6 mAh/cm2. 25 [0090] In this case, if the loading capacity is less than 16 3.7 mAh/cm2, it is difficult to ensure high capacity, and, if the loading capacity is greater than 10 mAh/cm2, cycle characteristics may be degraded while a non-uniform reaction is intensified at a surface of the electrode due to an 5 increase in thickness of the electrode. [0091] The positive electrode collector is not particularly limited so long as it has conductivity without causing adverse chemical changes in the battery, and, for example, 10 stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel that is surface-treated with one of carbon, nickel, titanium, silver, or the like may be used. [0092] The positive electrode active material is a compound capable of reversibly intercalating and deintercalating 15 lithium, wherein the positive electrode active material may specifically include a lithium composite metal oxide including lithium and at least one metal such as cobalt, manganese, nickel, or aluminum. Specifically, the lithium composite metal oxide may include lithium-manganese-based 20 oxide (e.g., LiMnO2, LiMn2O4, etc.), lithium-cobalt-based oxide (e.g., LiCoO2, etc.), lithium-nickel-based oxide (e.g., LiNiO2, etc.), lithium-nickel-manganese-based oxide (e.g., LiNi1-YMnYO2 (where 0