Lithium secondary battery

Abstract

The present invention relates to a lithium secondary battery comprising: a cathode; an anode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte, wherein the cathode comprises a cathode active material, the cathode active material comprises a lithium nickel-based oxide represented by a specific chemical formula, the non-aqueous electrolyte comprises a lithium salt, an organic solvent, a first additive, and a second additive, the first additive comprises a compound represented by a specific chemical formula, and the second additive comprises a compound represented by a specific chemical formula.

Description

lithium secondary battery Cross-citation with related applications This application claims the benefit of priority to Korean Patent Application No. 10-2023-0131252, filed September 27, 2023, and Korean Patent Application No. 10-2024-0118849, filed September 2, 2024, the entire contents of which are incorporated herein by reference. Technology field The present invention relates to a lithium secondary battery, and more particularly, to a lithium secondary battery having excellent high-temperature life characteristics, high-temperature storage characteristics, and thermal stability. Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing. The above lithium secondary battery is generally composed of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte that serves as a medium for transferring lithium ions, and a separator. At this time, carbon-based active materials, silicon-based active materials, etc. can be used as the negative electrode active material. In addition, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel-cobalt-manganese composite transition metal oxides can be used as the positive electrode active material. Meanwhile, lithium nickel-cobalt-manganese composite transition metal oxides with a nickel content of at least 70 mol% relative to the transition metal have recently been studied primarily to increase the energy density of the anode. However, increasing the nickel content of lithium nickel-cobalt-manganese composite transition metal oxides poses a problem: the thermal stability of the anode deteriorates. To prevent these problems, when the nickel content in the lithium nickel-cobalt-manganese composite transition metal oxide is lowered, the operating voltage must be increased to achieve the required energy density. However, during such high-voltage operation, as charge and discharge progress, the film formed on the surface of the positive / negative electrode or the electrode surface structure may deteriorate due to side reactions caused by deterioration of the electrolyte, and transition metal ions may be eluted from the surface of the positive electrode. In this way, the eluted transition metal ions are electrodeposited on the negative electrode and lower the passivation ability of the SEI, which causes the negative electrode to deteriorate. This deterioration phenomenon of secondary batteries tends to accelerate when the potential of the positive electrode increases or when the battery is exposed to high temperatures. Therefore, in order to solve these problems, research and development are being conducted on a method to stably form a durable film on the positive / negative electrode surfaces from the initial activation process, thereby suppressing electrolyte side reactions and the elution of metal ions from the positive electrode, and improving the life characteristics and stability at high temperatures. The present invention is intended to solve the above problems, and to provide a lithium secondary battery using a lithium transition metal oxide with a nickel content reduced to a specific level as a positive electrode active material, which has improved high-temperature life performance, storage performance, and thermal stability when driven at high voltage. [1] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte; wherein the positive electrode comprises a positive electrode active material, the positive electrode active material comprises a lithium nickel-based oxide represented by the following chemical formula 1, and the non-aqueous electrolyte comprises a lithium salt, an organic solvent, a first additive, and a second additive, wherein the first additive comprises a compound represented by the following chemical formula A, and the second additive comprises a compound represented by the following chemical formula C. [Chemical Formula 1] Li 1+x [Ni a Co b Mn c M 1 d ]O2 In the above chemical formula 1, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0 <b<0.2, 0<c≤0.4, 0≤d≤0.2이고, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. [Chemical Formula A] In the above chemical formula A, n is 1 or 2, L1 and L2 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and R1 and R2 are each independently a substituent represented by the following chemical formula B, [Chemical Formula B] In the above chemical formula B, m is 1 or 2, X1 and X2 are each independently -O- or -C(R 31 )(R 32 )-, but at least one of the above X1 and X2 is -O-, and R 31 Inland R 36are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, -C(=O)-R4 or -R5-OC(=O)-R6, wherein R4 and R6 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, wherein R5 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and the substituents of L1, L2, R4, R5 and R6 are each independently at least one selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2 and -SO3, and * is a position bonded to L1 or L2, but when both L1 and L2 are direct bonds, R1 and R2 are not CS-7 at the same time, and L1 and L2 are When both are methylene groups and n is 2, R1 and R2 are not CS-2 at the same time. [Chemical Formula C] In the above chemical formula C, R7 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and p is an integer selected from 0 to 6. [2] The present invention provides a lithium secondary battery, wherein, in the chemical formula 1, a / b is 3.2 to 9.0. [3] The present invention provides a lithium secondary battery, wherein in the chemical formula 1, in the above [1] or [2], a / c is 1.5 to 2.8. [4] The present invention, in at least one of the above [1] to [3], in the chemical formula 1, 0≤x≤0.2, a+b+c+d = 1, 0.55≤a≤0.65, 0 <b≤0.15, 0.2≤c≤0.4, 0≤d≤0.1, 4.0≤a / b≤8.5, 1.6≤a / c≤2.6인, 리튬 이차전지를 제공한다. [5] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [4], in the chemical formula A, R1 and R2 are each independently a substituent selected from the group consisting of CS-1 to CS-15. [6] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [5], R1 and R2 are each independently a substituent selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11. [7] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [6], L1 and L2 are methylene groups. [8] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to [7], the compound represented by the chemical formula A includes at least one selected from the group consisting of compounds A-1 to A-18. _ _ [9] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to [8], the compound represented by the chemical formula C includes at least one selected from the group consisting of a compound represented by the following chemical formula C-1 and a compound represented by the following chemical formula C-2. [Chemical Formula C-1] [Chemical Formula C-2] In the above chemical formulas C-1 and C-2, R7 is as defined in the above chemical formula C.

[0011] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to

[0010] , the weight ratio of the first additive and the second additive is 12:1 to 0.5:1.

[0012] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to

[0011] , the first additive is included in an amount of 0.01 wt% to 12 wt% based on the total weight of the non-aqueous electrolyte.

[0013] The present invention provides a lithium secondary battery, wherein, in at least one of the above [1] to

[0012] , the second additive is included in an amount of 0.01 wt% to 6 wt% based on the total weight of the non-aqueous electrolyte.

[0014] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to

[0013] , the lithium secondary battery has a charge cut-off voltage of 4.3 V or higher during operation.

[0015] The present invention provides a lithium secondary battery having a nominal voltage of 3.68 V or higher, in at least one of the above [1] to

[0014] . The lithium secondary battery according to the present invention comprises a positive electrode including a lithium nickel-based oxide satisfying a specific chemical formula as a positive electrode active material, a first additive (cyclic sulfur oxide represented by a specific chemical formula) and a second additive (a coumarin-based compound represented by a specific chemical formula), so that in the activation process of the lithium secondary battery, the second additive can be rapidly decomposed to form radicals, thereby rapidly promoting the ring-opening reaction of the first additive having a bulky structure, and a durable film can be quickly and stably formed on the positive / negative electrode surfaces from the initial activation process. Therefore, when a lithium secondary battery is driven at high voltage, the high-temperature lifespan characteristics and high-temperature storage characteristics of the lithium secondary battery can be improved, while the resistance can be reduced and the thermal stability of the lithium secondary battery can be improved. Hereinafter, the present invention will be described in more detail. Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way. The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, it should be understood that terms such as “include,” “have,” or “have” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof. Meanwhile, before explaining the present invention, unless otherwise specified, “*” in the present invention means a connected portion (bonding site) between the terminals of the same or different atoms or chemical formulas. In addition, in the description of "carbon number a0 to b0" in the present specification, "a0" and "b0" mean the number of carbon atoms included in a specific functional group. That is, the functional group may include "a0" to "b0" carbon atoms. For example, "an alkyl group having 1 to 5 carbon atoms" means an alkyl group including 1 to 5 carbon atoms, that is, CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2CH2-, etc. Additionally, in this specification, both alkyl groups and aryl groups may be substituted or unsubstituted. The above "substitution" means, unless otherwise defined, that at least one hydrogen bonded to carbon is replaced by an element other than hydrogen, for example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, a cycloalkynyl group having 3 to 12 carbon atoms, a heterocycloalkyl group having 3 to 12 carbon atoms, a heterocycloalkenyl group having 3 to 12 carbon atoms, a heterocycloalkynyl group having 2 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group, an aryl group having 6 to 20 carbon atoms, an aryl group having 2 to 20 carbon atoms, an alkyl ... It means substituted with a heteroaryl group having 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, etc. The inventors of the present invention have conducted repeated studies to solve the problem of deterioration of high-temperature lifespan and storage characteristics of a lithium secondary battery due to electrolyte side reactions and positive electrode transition metal dissolution when a lithium nickel-based oxide represented by a specific chemical formula is used as a positive electrode active material and a lithium secondary battery is driven at high voltage, and as a result, they have found that when a first additive and a second additive represented by a specific chemical formula are included together in a non-aqueous electrolyte, a durable film is stably and quickly formed on the positive / negative electrodes in the initial activation process, thereby realizing a lithium secondary battery having excellent high-temperature lifespan characteristics, storage characteristics, and thermal stability at high voltage, and have completed the present invention. Hereinafter, the present invention will be described in detail. A lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may comprise any combination between technically possible configurations among the configurations below. lithium secondary battery A lithium secondary battery according to the present invention comprises a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode active material, wherein the positive electrode active material comprises a lithium nickel-based oxide represented by the following chemical formula 1, and the non-aqueous electrolyte comprises a lithium salt, an organic solvent, a first additive, and a second additive, wherein the first additive comprises a compound represented by the following chemical formula A, and the second additive comprises a compound represented by the following chemical formula C. [Chemical Formula 1] Li 1+x [Ni a Co b Mn c M 1 d ]O2 In the above chemical formula 1, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0 <b<0.2, 0<c≤0.4, 0≤d≤0.2이고, M 1is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. [Chemical Formula A] In the above chemical formula A, n is 1 or 2, L1 and L2 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and R1 and R2 are each independently a substituent represented by the following chemical formula B. [Chemical Formula B] In the above chemical formula B, m is 1 or 2, X1 and X2 are each independently -O- or -C(R 31 )(R 32 )-, but at least one of the above X1 and X2 is -O-, and R 31 Inland R 36 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, -C(=O)-R4 or -R5-OC(=O)-R6, wherein R4 and R6 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, wherein R5 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and the substituents of L1, L2, R4, R5 and R6 are each independently at least one selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2 and -SO3, and * is a position bonded to L1 or L2, but when both L1 and L2 are direct bonds, R1 and R2 are not CS-7 at the same time, and L1 and L2 are When both are methylene groups and n is 2, R1 and R2 are not CS-2 at the same time. [Chemical Formula C] In the above chemical formula C, R7 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and p is an integer selected from 0 to 6. The lithium secondary battery includes a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte. Specifically, the lithium secondary battery includes a positive electrode; a negative electrode opposite the positive electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte. The above lithium secondary battery can be manufactured according to a conventional method known in the art. For example, the above lithium secondary battery can be manufactured by sequentially stacking the positive electrode; the negative electrode opposite the positive electrode; and the separator interposed between the positive electrode and the negative electrode; to form an electrode assembly, then housing the electrode assembly in a battery case, and then injecting the non-aqueous electrolyte into the battery case. (1) Bipolar The positive electrode includes a positive electrode active material. Specifically, the positive electrode may include a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector; and the positive electrode active material may be included in the positive electrode active material layer. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the positive electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and an aluminum-cadmium alloy, preferably aluminum. The thickness of the above positive electrode collector may typically be 3 to 500 μm. The above-described positive electrode current collector may also form fine irregularities on its surface to enhance the bonding strength of the positive electrode active material. For example, the above-described positive electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric. The positive electrode active material layer may be disposed on at least one side of the positive electrode current collector, specifically on one or both sides of the positive electrode current collector. The positive electrode active material layer may have a single layer or a multilayer structure of two or more layers. The above positive electrode active material includes a lithium nickel-based oxide represented by the following chemical formula 1. [Chemical Formula 1] Li 1+x [Ni a Co b Mn c M 1 d ]O2 In the above chemical formula 1, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0 <b<0.2, 0<c≤0.4, 0≤d≤0.2이고, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. The above lithium nickel-based oxide is distinct from, for example, a high-nickel lithium transition metal oxide containing more than 70 mol% of nickel among all metals excluding lithium. The high-nickel lithium transition metal oxide is undesirable in that it contains a large amount of nickel, which causes a decrease in thermal stability, and in particular, it degenerates into a rock salt form due to structural changes within the lattice at high voltage, which reduces lithium mobility and causes a decrease in performance. Meanwhile, since the lithium nickel-based oxide has a lower nickel content than high-nickel lithium transition metal oxides, it needs to be driven at a high voltage (e.g., 4.3 V or higher) to increase the energy density of the positive electrode. However, during such high-voltage driving, oxygen is desorbed according to changes in the oxidation states of nickel and cobalt, which intensifies electrolyte side reactions, resulting in a significant decrease in lifespan performance and storage performance. The lithium secondary battery according to the present invention is characterized in that, in order to achieve both high energy density and excellent life performance and storage performance, the lithium secondary battery uses the lithium nickel-based oxide represented by the above chemical formula 1 as a positive electrode active material, and the first additive and the second additive described below are used in combination. The lithium secondary battery of the present invention can quickly and stably form a film having reduced resistance and excellent durability on the positive electrode by promoting the ring-opening reaction of the first additive by the second additive, and in particular, it is possible to improve the high-temperature life performance, high-temperature storage performance, and thermal stability of a lithium secondary battery that requires high-voltage use. Meanwhile, it is difficult to achieve high capacity in lithium nickel oxides containing less than 50 mol% of nickel (Ni) among all metals excluding lithium. In addition, Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2, Li[Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 ]O2, etc. In the case of high nickel lithium transition metal oxides, the proportion of Ni among the transition metals or the molar ratio of Ni / Mn is very high, and the change in the axis within the lattice due to the increase and decrease of Ni oxidation number during the charge / discharge process is large, so the surface side reaction is aggravated by Ni, which is unstable in terms of energy, and it is difficult to express the performance improvement effect by forming a cathode / negative film through the first and second additives. In addition, Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2, Li[Ni0.86 Co 0.05 Mn 0.07 Al 0.02 ]O2 and other high nickel lithium transition metal oxides have a high molar ratio of Ni / Mn, so that a large amount of rock-salt structure exists on the surface due to phase change when driven at high voltage, which makes it difficult to insert and de-insert lithium ions and form a positive electrode film by combining the above additives. In addition, Li[Ni 0.6 Co 0.2 Mn 0.2 ] In the case of lithium cobalt-based oxides containing relatively large amounts of cobalt (Co), such as O2 and LiCoO2, the proportion of Co in the transition metal is very high, which increases the irreversibility within the structure, making it difficult to exhibit the performance improvement effect by forming a positive electrode film using an additive. Therefore, in the case of a lithium nickel-based oxide other than the above-described chemical formula 1, it is difficult to improve the desired life performance and storage performance even when the first and second additives are used in combination. In the above chemical formula 1, x may be 0≤x≤0.5, specifically 0≤x≤0.2, and more specifically 0≤x≤0.1. The above x represents the molar ratio of lithium in the lithium nickel-based oxide particles, and when the above range is satisfied, the positive electrode active material can form a stable layered crystal structure. In the above chemical formula 1, a may be 0.5≤a≤0.7, specifically 0.52≤a≤0.68, and more specifically 0.55≤a≤0.65. The above a represents the molar ratio of nickel among the total metal excluding lithium in the lithium nickel-based oxide particles, and when the above range is satisfied, as described above, the high-temperature storage characteristics, high-temperature life characteristics, and thermal stability may be excellent when driven at a high voltage. In the above chemical formula 1, b is 0 <b<0.2, 구체적으로 0<b≤0.18, 보다 구체적으로 0<b≤0.16, 보다 더 구체적으로 0<b≤0.15일 수 있다. 상기 b는 상기 화학식 1로 표시되는 리튬 니켈계 산화물에 있어서, 리튬을 제외한 전체 금속 중 Co가 차지하는 몰 비를 나타내는 것으로 상기 범위를 만족하는 경우, Co 함량을 낮춤으로써 비용적인 이점을 가지며, 양호한 저항 특성 및 출력 특성을 구현할 수 있고, 상대적으로 Mn의 비율을 높여 양극 활물질의 구조적 안정성을 향상시킬 수 있다. In the above chemical formula 1, c is 0 <c≤0.4, 구체적으로 0.1≤c≤0.4, 보다 구체적으로는 0.15≤c≤0.4, 보다 더 구체적으로 0.2≤c≤0.4일 수 있다. 상기 c는 상기 화학식 1로 표시되는 리튬 니켈계 산화물에 있어서, 리튬을 제외한 전체 금속 중 Mn이 차지하는 몰 비를 나타내는 것으로, 상기 범위를 만족하는 경우, 양극 활물질의 구조적 안정성을 향상시킬 수 있다. In the above chemical formula 1, M 1 can be understood as a doping element of lithium nickel-based oxide, and specifically, it can be at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo. At this time, d can be 0≤d≤0.2, specifically 0≤d≤0.15, and more specifically 0≤d≤0.10. In the lithium nickel-based oxide represented by the chemical formula 1, M is the total metal excluding lithium. 1 This represents the molar ratio of elements, and when the above range is satisfied, it can play a role in promoting particle growth during sintering of the positive electrode active material or improving crystal structure stability. Meanwhile, in the above chemical formula 1, the a / b may be 3.2 to 9.0, specifically 4.0 to 8.5, more specifically 5.0 to 8.0, and even more specifically 5.5 to 7.0. When the above range is satisfied, high capacity can be realized by including a high content of nickel (Ni), and the crystal structure of the positive electrode may not collapse after the high capacity is expressed, so that the lifespan characteristics are excellent. In addition, when the cobalt (Co) content is high, a thick irreversible film is formed on the positive / negative electrode surface, but when the a / b range is satisfied, the thickness of the irreversible film is reduced, so that the first additive and the second additive can stably form a film, so that the electrochemical characteristics of the battery can be excellent. In the above chemical formula 1, the a / c may be 1.5 to 2.8, specifically 1.6 to 2.6, more specifically 1.7 to 2.4, even more specifically 1.8 to 2.3, and even more specifically 1.9 to 2.1. When the above range is satisfied, the variability in the c-axis direction within the layered structure during charge and discharge is suppressed by manganese (Mn), and at the same time, capacity expression by nickel (Ni) is stably possible, so that the electrochemical characteristics of the battery may be excellent. The above positive electrode active material may be included in an amount of 80 wt% to 99 wt%, preferably 92 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, taking into account sufficient capacity of the positive electrode active material, etc. The above positive electrode active material layer may further include a binder and / or a conductive material together with the positive electrode active material. The above binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and specifically, may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride. The above binder may be included in the positive electrode active material layer at 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%, in order to sufficiently secure binding force between components such as the positive electrode active material. The conductive material may be used to assist and improve conductivity in a secondary battery, and is not particularly limited as long as it has conductivity without causing chemical changes. Specifically, the positive electrode conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black, etc.; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably, in terms of improving conductivity, may include carbon nanotubes. The above conductive material may be included in the positive electrode active material layer in an amount of 0.1 wt% to 20 wt%, preferably 0.1 wt% to 10 wt%, and more preferably 0.3 wt% to 5 wt%, in order to sufficiently secure electrical conductivity. The thickness of the positive electrode active material layer may be 30 µm to 400 µm, preferably 40 µm to 200 µm. The above positive electrode can be manufactured according to a conventional positive electrode manufacturing method. For example, the positive electrode can be manufactured by mixing a positive electrode active material, a positive electrode binder, and / or a positive electrode conductive material in a positive electrode solvent to manufacture a positive electrode slurry, applying the positive electrode slurry onto a positive electrode current collector, and then drying and rolling. The above-mentioned positive electrode solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode. The solid content of the above positive electrode slurry may be 40 wt% to 90 wt%, specifically 50 wt% to 80 wt%. Alternatively, the positive electrode may be manufactured by casting the positive electrode slurry onto a separate support, then peeling the resulting film from the support and laminating it onto a positive electrode current collector. (2) Cathode The above cathode may be opposite to the above anode. The above negative electrode includes a negative electrode active material. Specifically, the negative electrode may include a negative electrode current collector; and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; and the negative electrode active material may be included in the negative electrode active material layer. The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. The above negative electrode current collector may typically have a thickness of 3 to 500 μm. In addition, the negative electrode current collector, like the positive electrode current collector, can form fine irregularities on the surface of the negative electrode current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric. The negative electrode active material layer may be positioned on the positive electrode current collector, and specifically, may be positioned on one or both sides of the negative electrode current collector. The negative electrode active material layer may have a single layer or a multilayer structure of two or more layers. As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; (semi-)metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β (0 <β < 2), a metalloid oxide capable of doping and dedoping lithium, such as SnO2, vanadium oxide, lithium vanadium oxide; or a composite comprising the metalloid compound and a carbonaceous material, such as a Si-C composite or a Sn-C composite, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbon material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include amorphous, plate-like, flaky, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes. The above negative active material may be included in the negative active material layer in an amount of 60 wt% to 99 wt%, preferably 75 wt% to 95 wt%. Meanwhile, the negative electrode active material layer may optionally further include a conductive material and a binder in addition to the negative electrode active material. The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, any conductive material that does not cause a chemical change and has electronic conductivity can be used without special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may typically be included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the negative electrode active material layer. The above binder serves to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof may be used. The above binder may be included in an amount of 1 to 30 wt%, preferably 1 to 20 wt%, and more preferably 1 to 10 wt%, based on the total weight of the negative electrode active material layer. The thickness of the negative electrode active material layer may be 10 µm to 200 µm, preferably 20 µm to 150 µm. The above negative electrode can be manufactured according to a conventional negative electrode manufacturing method. For example, the negative electrode can be manufactured by mixing a negative electrode active material, a negative electrode conductive material, and / or a negative electrode conductive material in a negative electrode solvent to manufacture a positive electrode slurry, applying the negative electrode slurry onto a negative electrode current collector, and drying and rolling. The cathode solvent may include at least one selected from the group consisting of distilled water, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate dispersion of the components of the cathode slurry. The solid content of the above cathode slurry may be 30 wt% to 80 wt%, specifically 40 wt% to 70 wt%. Alternatively, the negative electrode may be manufactured by casting the negative electrode slurry onto a separate support, then peeling the film from the support and laminating the resulting film onto a negative electrode current collector. (3) Membrane The above separator is interposed between the anode and the cathode. In addition, as the separator, a conventional porous polymer film used as a separator in the past, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, may be used alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used as the separator in order to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure. (4) Non-aqueous electrolyte The above non-aqueous electrolyte comprises a lithium salt, an organic solvent, a first additive, and a second additive. 1) Lithium salt As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation. For example, the lithium salt may be Li as a cation. + , and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N -It may include at least one selected from the group consisting of . Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one 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). The lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, specifically at a concentration of 0.8 M to 4 M, and more specifically at a concentration of 0.8 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the lithium ion yield (Li + The output characteristics of the battery can be improved by improving the transference number and the degree of dissociation of lithium ions. 2) Organic solvent The organic solvent mentioned above is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery can be minimized. Specifically, the organic solvent may include at least one 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. Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof. The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent having a high dielectric constant and thus capable of dissociating a lithium salt in an electrolyte well, and specifically, may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and more specifically, may include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically, may include ethylene carbonate (EC). In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may specifically include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and more specifically may include at least one selected from the group consisting of ethylmethyl carbonate (EMC) and diethyl carbonate (DEC), and more specifically may include ethylmethyl carbonate (EMC). The above organic solvent may be a mixture of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. At this time, the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed in a volume ratio of 5:95 to 40:60, specifically, a volume ratio of 10:90 to 25:75. When the mixing ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent satisfies the above range, high dielectric constant and low viscosity characteristics can be simultaneously satisfied, and excellent ionic conductivity characteristics can be implemented. In addition, the organic solvent may further include at least one carbonate organic solvent selected from the group consisting of the cyclic carbonate organic solvent and the linear carbonate organic solvent, and at least one ester organic solvent selected from the group consisting of the linear ester organic solvent and the cyclic ester organic solvent, in order to produce an electrolyte having high ionic conductivity. The linear ester organic solvent may specifically 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. In addition, the cyclic ester organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. Meanwhile, the organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes as needed. For example, at least one organic solvent among an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent may be additionally included. As the above ether solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto. The above glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents, and is a solvent with low reactivity with metals, and may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto. The above nitrile solvent may be at least one selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto. 3) First additive The above first additive comprises a compound represented by the following chemical formula A. [Chemical Formula A] In the above chemical formula A, n is 1 or 2, L1 and L2 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and R1 and R2 are each independently a substituent represented by the following chemical formula B. [Chemical Formula B] In the above chemical formula B, m is 1 or 2, X1 and X2 are each independently -O- or -C(R 31 )(R 32 )-, but at least one of the above X1 and X2 is -O-, and R 31 Inland R 36 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, -C(=O)-R4 or -R5-OC(=O)-R6, wherein R4 and R6 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, wherein R5 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, and the substituents of L1, L2, R4, R5 and R6 are each independently at least one selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2 and -SO3, and * is a position bonded to L1 or L2, but when both L1 and L2 are direct bonds, R1 and R2 are not CS-7 at the same time, and L1 and L2 are When both are methylene groups and n is 2, R1 and R2 are not CS-2 at the same time. The compound represented by the above chemical formula A is characterized by having a sulfur oxide structure at the center and, at the same time, a cyclic sulfur oxide structure at both ends. By adopting this chemical structure, the compound represented by the above chemical formula A can induce stable formation of anions when applied as a non-aqueous electrolyte additive, and further, can form a stable SEI layer. In particular, cyclic sulfur oxide additives (e.g., 1,3-propane sultone) that have been conventionally used as electrolyte additives have the disadvantage of being structurally unstable, which can cause unnecessary side reactions and easily induce toxic substances. In comparison, the compound represented by the above chemical formula A improves chemical reaction stability by linking a reactive site with low chemical stability with a linker, and maintains a cyclic structural form, thereby reducing unnecessary side reactions and enabling the additive to fully participate in the SEI film-forming reaction. In addition, the compound represented by the above chemical formula A has an advantage in that the structure of the monomer is enlarged, which improves the reaction surface coverage characteristics accordingly, and thus can effectively form an SEI film even in a small amount. Accordingly, when the compound represented by the above chemical formula A is used as an electrolyte additive, the SEI layer can be formed more stably than in the past. Specifically, in the compound represented by the above chemical formula A, R1 and R2 may each be independently selected from the group consisting of CS-1 to CS-15: The substituent structures CS-1 to CS-15 listed above are preferred examples of R1 and R2 of chemical formula A, and when the substituents of CS-1 to CS-15 are applied as R1 and R2 of chemical formula A, the overall compound has excellent structural stability while also smoothly performing its function as a non-aqueous electrolyte additive. In particular, it may be preferred that R1 and R2 are each independently selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11 in terms of structural stability and ease of synthesis. Meanwhile, in the compound represented by the chemical formula A of the present invention, if both L1 and L2 are direct bonds and R1 and R2 are CS-7, or if both L1 and L2 are methylene groups and n is 2 and R1 and R2 are both CS-2, the structural stability of the compound itself is low and it can be easily decomposed, and thus the synthesis of the compound itself can be difficult. In particular, compounds that satisfy the above conditions have the disadvantage that the R1 and R2 structures having a ring form are easily decomposed during the synthesis process, and even if the compound is ultimately synthesized, it can be easily decomposed during the storage process, and the synthesis yield is also significantly low. Therefore, the present invention excludes compounds in which both L1 and L2 are direct bonds and R1 and R2 are CS-7, and in which n is 2 and R1 and R2 are both CS-2. In the compound represented by the above chemical formula A, L1 and L2 may each independently be a direct bond, a methylene group, or an ethylene group, and particularly preferably a methylene group. When L1 and L2 are methylene groups, the synthesis of the compound is easy, and decomposition of the compound after synthesis can be suppressed. More specifically, it may be particularly preferable that the compound represented by the above chemical formula A includes at least one selected from the group consisting of the following compounds A-1 to A-18: When the compound represented by the above chemical formula A has a structure described as preferable above, it has the advantage of being able to form a stable SEI layer with low resistance even with a smaller amount compared to the additives used previously. The first additive may be included in the non-aqueous electrolyte in an amount of 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, 2 wt% or more, 2.5 wt% or more, 3 wt% or more, 3.5 wt% or more, 4 wt% or more, 4.5 wt% or more, and may be included in an amount of 12 wt% or less, 11.5 wt% or less, 11 wt% or less, 10.5 wt% or less, 10 wt% or less, 9.5 wt% or less, 9 wt% or less, 8.5 wt% or less, 8 wt% or less, 7.5 wt% or less, 7 wt% or less, 6.5 wt% or less, 6 wt% or less, 5.5 wt% or less. For example, the first additive may be included in an amount of 0.01 wt% to 12 wt%, specifically 1 wt% to 11 wt%, more specifically 2 wt% to 10 wt%, even more specifically 3 wt% to 7 wt%, and even more specifically 4 wt% to 6 wt%, based on the total weight of the non-aqueous electrolyte. When the above range is satisfied, it is preferable in that the life performance and storage performance improvement effect of the secondary battery described above can be exhibited while preventing an increase in resistance due to excessive use of the additive. 4) Second additive The second additive comprises a compound represented by the following chemical formula C. [Chemical Formula C] In the above chemical formula C, R7 includes a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, and p is an integer selected from 0 to 6. The compound represented by the chemical formula C included in the second additive is a coumarin-based compound, which has strong reducibility at the cathode and thus can rapidly undergo a ring-opening reaction during initial SEI film formation, thereby forming a PEO-based polymer-type SEI film. Such a polymer-type SEI film can have excellent flexibility and resilience. However, when the second additive is used alone, there is a concern that the thermal stability and chemical and electrochemical stability of the film formed on the positive / negative electrodes may deteriorate, and there is a problem of reduced durability. For example, when the second additive is used alone, a durable SEI film cannot be formed for a negative electrode active material (e.g., a silicon-based active material) that undergoes volume expansion during charge and discharge. In addition, when the second additive is used alone, it may be reduced to form radicals and then attack a carbonate-based solvent, causing an unwanted additional reduction reaction. In this respect, the non-aqueous electrolyte according to the present invention uses a first additive including cyclic sulfur oxides at both ends in combination with the second additive, and due to the promotion of the ring-opening reaction of the first additive according to the radical formation of the second additive, a film having excellent flexibility, recoverability, and durability such as thermal stability can be formed on the positive / negative electrode. Specifically, the compound represented by the above chemical formula A forms a film on the positive / negative electrode by a ring-opening reaction of cyclic sulfur oxide, but has a problem in that the reaction participation rate is low due to its steric hinderance. Therefore, when the compound represented by the above chemical formula A is used alone, it is difficult to form the desired positive / negative electrode film due to the low reaction participation rate. However, according to the present invention, by using the first additive and the second additive in combination, radicals are formed from the first additive in the initial activation stage of the lithium secondary battery, and the radicals can promote the ring-opening reaction of the compound represented by the above chemical formula A, and as a result, a positive / negative electrode film rich in oxygen (O) based on sulfur (S) is quickly and stably formed, thereby enabling the implementation of a lithium secondary battery having excellent lithium mobility characteristics, high-temperature lifespan performance, and high-temperature storage performance. In addition, when the first and second additives are used together, a film having excellent coverage and improved durability can be formed on the positive / negative electrodes due to the formation of radicals by the second additive and the promotion of the ring-opening reaction of the first additive by the radicals, which is preferable. The effect of improving high-temperature life performance and high-temperature storage performance due to the organic action of the first and second additives is more prominent in high-voltage use, and in particular, the above-described active material is an effect exhibited when the lithium nickel-based oxide represented by the above chemical formula 1 is used as the positive electrode active material. In the above chemical formula C, R7 may be specifically a halogen (the halogen may be selected from F, Cl, Br, and I, and may be specifically F), a nitrile group, a propargyl group, an ester group, an ether group, or a combination of two or more thereof, and such a substituent is preferable in that it has excellent reducibility, is advantageous in forming a polymer-type SEI layer, and also has excellent lithium ion transport performance. In the above chemical formula C, p may be an integer selected from 0 to 6, specifically an integer selected from 1 to 6, and more specifically, p may be 1. In the above chemical formula C, when p is 2 or more, each R7 may be the same or different. Specifically, the compound represented by the above chemical formula C may include at least one selected from the group consisting of a compound represented by the following chemical formula C-1 and a compound represented by the following chemical formula C-2. [Chemical Formula C-1] [Chemical Formula C-2] In the above chemical formulas C-1 and C-2, R7 is as defined in the above chemical formula C. The compounds represented by the above chemical formulas C-1 and C-2 have structures in which substituents exist at positions 3 and 7 (based on IUPAC nomenclature) of the ring structure, respectively. In this case, it is preferable to synthesize at these positions compared to other substitution positions in that it is advantageous. In particular, the compound represented by the above chemical formula C-1 in which the substituent exists at position 3 is more preferable in that the uniformity of the reaction is improved when reduced to the cathode. Specifically, the compound represented by the above chemical formula C may include at least one selected from the group consisting of compounds represented by the following chemical formulas C-3 to C-11. The compound represented by the above chemical formula C may specifically include at least one selected from the group consisting of compounds represented by the following chemical formulas C-3 to C-11 in terms of being more smoothly reduced at the negative electrode and thus more advantageous for forming a polymer-type SEI layer, and more specifically, may include at least one selected from the group consisting of the following chemical formulas C-3, C-4 and C-6, and even more specifically, the compound represented by the above chemical formula C may include a compound represented by the following chemical formula C-3 in terms of having strong reducibility and an excellent transition metal dissolution inhibition effect in addition to the above-described effects. [Chemical Formula C-3] [Chemical Formula C-4] [Chemical Formula C-5] [Chemical Formula C-6] [Chemical Formula C-7] [Chemical Formula C-8] [Chemical Formula C-9] [Chemical Formula C-10] [Chemical Formula C-11] The second additive may be included in an amount of 0.01 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, and may be included in an amount of 6 wt% or less, 5.5 wt% or less, 5 wt% or less, 4.5 wt% or less, 4 wt% or less, 3.5 wt% or less, 3 wt% or less, 2.5 wt% or less, 2 wt% or less, 1.5 wt% or less, 1.3 wt% or less, based on the total weight of the non-aqueous electrolyte. For example, the second additive may be included in an amount of 0.01 wt% to 6 wt%, specifically 0.5 wt% to 5 wt%, more specifically 0.6 wt% to 3 wt%, more specifically 0.7 wt% to 2 wt%, and even more specifically 0.8 wt% to 1.3 wt%, based on the total weight of the non-aqueous electrolyte. When the content of the second additive satisfies the above range, it is preferable in that it provides sufficient flexibility and resilience to the SEI film, while preventing an increase in resistance of the lithium secondary battery due to excessive addition and a decrease in life performance resulting therefrom. Meanwhile, the weight ratio of the first additive and the second additive may be 12:1 to 0.5:1, specifically, 10:1 to 1:1, more specifically, 7:1 to 3:1, and even more specifically, 6:1 to 4:1. When the above range is satisfied, an appropriate amount of positive / negative film can be formed, and an appropriate amount of radicals can be formed to promote the ring-opening reaction of the first additive, so that the film formation can proceed quickly, thereby improving high-temperature storage characteristics and high-temperature life characteristics. The non-aqueous electrolyte may further include a third additive in addition to the first and second additives. The third additive may be included in the non-aqueous electrolyte to prevent the non-aqueous electrolyte from decomposing and causing cathode collapse in a high-power environment, or to provide low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and suppression of battery expansion at high temperatures. Specifically, the third additive may include at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, 1,4-butane sultone, ethane sultone, succinonitrile, adiponitrile, ethylene sulfate, lithium difluoro phosphate (LiDFP), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiODFB), lithium bis-(oxalato)borate (LiBOB), and tris(trimethylsilyl) phosphate (TMSPi). The third additive may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 15 wt%. The charge cut-off voltage during operation of the lithium secondary battery of the present invention may be 4.3 V or higher, specifically 4.35 V or higher, and more specifically 4.4 V or higher. The lithium secondary battery of the present invention can achieve excellent energy density and improved high-temperature lifespan performance and high-temperature storage performance at high operating voltages by combining the aforementioned positive electrode and non-aqueous electrolyte. Meanwhile, the lithium secondary battery may have a nominal voltage of 3.68 V or higher, preferably 3.68 V to 3.80 V, and more preferably 3.69 V to 3.75 V. At this time, the nominal voltage refers to the average voltage value during discharge of the lithium secondary battery. Since the energy density of the lithium secondary battery is calculated by the product of the average voltage and the average current during discharge, the energy density increases when the nominal voltage is high. The nominal voltage of a conventional lithium secondary battery using a lithium nickel cobalt manganese oxide as a positive electrode active material was at the level of 3.6 V, but in the present invention, the charge cut-off voltage is increased to make the nominal voltage 3.68 V or higher, thereby enabling high energy density to be implemented. Specifically, the lithium secondary battery according to the present invention may have an energy density of 500 Wh / L or higher, 550 Wh / L or higher, or 500 Wh / L to 800 Wh / L. There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape. In addition, since the lithium secondary battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs). Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided. The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system. Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims. Examples and Comparative Examples Example 1 <Manufacturing of non-aqueous electrolyte> As an organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80 was used. A non-aqueous electrolyte was prepared by adding LiPF6 as a lithium salt to the above organic solvent, [Compound A-1] as a first additive, and a compound represented by the following [Chemical Formula C-3] as a second additive. [Compound A-1] [Chemical Formula C-3] The above LiPF6 was included in the non-aqueous electrolyte at a molar concentration of 1.2 M. The first additive was included in the non-aqueous electrolyte at 5.0 wt%, and the second additive was included in the non-aqueous electrolyte at 1.0 wt%. Lithium secondary battery manufacturing Cathode active material (Li[Ni 0.6 Co 0.1 Mn 0.3]O2): Conductive agent (carbon nanotube): Binder (polyvinylidene fluoride) was added to N-methyl-2-pyrrolidone (NMP), a solvent, in a weight ratio of 97.74:0.70:1.56 to prepare a positive electrode slurry (solid content 75.5 wt%). The positive electrode slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 15 μm, dried, and roll pressed to form a positive electrode active material layer (thickness: 136.6 μm), which was used as a positive electrode. A negative electrode slurry (solid content 26 wt%) was prepared by adding a negative electrode active material (natural graphite): conductive agent (carbon black): binder (styrene-butadiene rubber (SBR) / carboxymethyl cellulose (CMC)) to distilled water as a solvent in a weight ratio of 96.15:1.55:2.30. The negative electrode slurry was applied to one surface of a 15 μm thick negative electrode current collector (Cu thin film), dried, and roll pressed to form a negative electrode active material layer (thickness: 179.8 μm), which was used as a negative electrode. A polyethylene porous film separator was interposed between the positive and negative electrodes manufactured above in a dry room, and then the non-aqueous electrolyte manufactured above was injected to manufacture a secondary battery. Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the first additive was added to the non-aqueous electrolyte in an amount of 10 wt% instead of 5.0 wt%. Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the first additive was added to the non-aqueous electrolyte in an amount of 1.0 wt% instead of 5.0 wt%. Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the second additive was added to the non-aqueous electrolyte in an amount of 0.5 wt% instead of 1.0 wt%. Example 5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the second additive was added to the non-aqueous electrolyte in an amount of 5.0 wt% instead of 1.0 wt%. Example 6 A lithium secondary battery was manufactured in the same manner as in Example 1, except that [Compound A-4] was used as the first additive. [Compound A-4] Example 7 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a compound represented by the following chemical formula C-4-1 was used as the second additive. [Chemical formula C-4-1] Example 8 A lithium secondary battery was manufactured in the same manner as Example 1, except that the compound represented by [Compound A-4] as the first additive and the compound represented by [Chemical Formula C-4-1] as the second additive were used. Comparative Example 1 A lithium secondary battery was manufactured in the same manner as Example 1, except that the first and second additives were not added to the non-aqueous electrolyte. Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the second additive was not added to the non-aqueous electrolyte. Comparative Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the first additive was not added to the non-aqueous electrolyte. Comparative Example 4 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.8 Co 0.1 Mn 0.1]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used. Comparative Example 5 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.8 Co 0.1 Mn 0.1 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the second additive was not added to the non-aqueous electrolyte. Comparative Example 6 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.8 Co 0.1 Mn 0.1 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the first additive was not added to the non-aqueous electrolyte. Comparative Example 7 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used. Comparative Example 8 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the second additive was not added to the non-aqueous electrolyte. Comparative Example 9 Li[Ni as a cathode active material 0.6 Co 0.1 Mn0.3 ]O2 instead of Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the first additive was not added to the non-aqueous electrolyte. Comparative Example 10 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiCoO2 was used instead of O2. Comparative Example 11 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiCoO2 was used instead of O2 and the second additive was not added to the non-aqueous electrolyte. Comparative Example 12 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiCoO2 was used instead of O2 and the first additive was not added to the non-aqueous electrolyte. Comparative Example 13 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.6 Co 0.2 Mn 0.2 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used. Comparative Example 14 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.6 Co 0.2 Mn 0.2]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the second additive was not added to the non-aqueous electrolyte. Comparative Example 15 Li[Ni as a cathode active material 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.6 Co 0.2 Mn 0.2 ]A lithium secondary battery was manufactured in the same manner as in Example 1, except that O2 was used and the first additive was not added to the non-aqueous electrolyte. Comparative Example 16 A lithium secondary battery was manufactured in the same manner as in Example 1, except that 1,3-propane sultone was used as the first additive. Cathode active materialNon-aqueous electrolyte compositionLithium salt (LiPF6)Organic solventAdditiveMolar concentration (M)First additiveSecond additiveContent (wt%, based on non-aqueous electrolyte)Content (wt%, based on non-aqueous electrolyte)Example 1Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Example 2Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)10.01.0Example 3Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)1.01.0Example 4Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.00.5Example 5Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.05.0Example 6Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Example 7Li[Ni0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Example 8Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Comparative example 1Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)--Comparative example 2Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.0-Comparative example 3Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)-1.0Comparative example 4Li[Ni 0.8 Co 0.1 Mn 0.1 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Comparative example 5Li[Ni 0.8 Co 0.1 Mn 0.1 ]O21.2EC:EMC (volume ratio 20:80)5.0-Comparative example 6Li[Ni 0.8 Co 0.1 Mn 0.1 ]O21.2EC:EMC (volume ratio 20:80)-1.0Comparative example 7Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Comparative example 8Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]O21.2EC:EMC (volume ratio 20:80)5.0-Comparative example 9Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01]O21.2EC:EMC (volume ratio 20:80)-1.0Comparative example 10LiCoO21.2EC:EMC (volume ratio 20:80)5.01.0Comparative example 11LiCoO21.2EC:EMC (volume ratio 20:80)5.0-Comparative example 12LiCoO21.2EC:EMC (volume ratio 20:80)-1.0Comparative example 13Li[Ni 0.6 Co 0.2 Mn 0.2 ]O21.2EC:EMC (volume ratio 20:80)5.01.0Comparative example 14Li[Ni 0.6 Co 0.2 Mn 0.2 ]O21.2EC:EMC (volume ratio 20:80)5.0-Comparative example 15Li[Ni 0.6 Co 0.2 Mn 0.2 ]O21.2EC:EMC (volume ratio 20:80)-1.0Comparative example 16Li[Ni 0.6 Co 0.1 Mn 0.3 ]O21.2EC:EMC (volume ratio 20:80)5.01.0 Experimental Example 1: High-Temperature Cycle Performance Test The lithium secondary batteries manufactured in Examples 1 to 8 and Comparative Examples 1 to 16 above were charged to 4.4 V, 0.05 C at 45°C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions, and then discharged to 2.5 V under CC, 0.33 C conditions, which constituted one cycle, and 400 cycles of charge / discharge were performed. (1) Capacity retention rate The capacity retention rate is calculated using the formula below, and the results are shown in Table 2 below. Capacity retention (%) = {(discharge capacity after 400 cycles / discharge capacity after 1 cycle)} Х 100 (2) Resistance increase rate After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger and discharger, the SOC was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse was applied. After 400 cycles of charge and discharge, the resistance after 400 cycles was calculated using the same method as above, and the resistance increase rate was calculated using the equation below, and the results are shown in Table 2 below. Resistance increase rate (%) = (Resistance after 400 cycles - Initial resistance) / Initial resistance Х 100 Capacity retention rate (%) Resistance increase rate (%) Example 19019 Example 28820 Example 38822 Example 48721 Example 58923 Example 68920 Example 78819 Example 88820 Comparative Example 15549 Comparative Example 25645 Comparative Example 35642 Comparative Example 46747 Comparative Example 56647 Comparative Example 66951 Comparative Example 76449 Comparative Example 86748 Comparative Example 96955 Comparative Example 106547 Comparative Example 116350 Comparative Example 126548 Comparative Example 135752 Comparative Example 145950 Comparative Example 155850 Comparative Example 165449 Referring to Table 2 above, Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2 as a cathode active material and a non-aqueous electrolyte including the first additive and the second additive as additives, it can be confirmed that the lithium secondary batteries of Examples 1 to 8 have a higher capacity retention rate and a lower resistance increase rate during high-voltage, high-temperature cycle charge and discharge than the comparative examples 1 to 16. Specifically, Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2, Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]O 2, LiCoO 2, Li[Ni 0.6 Co 0.2 Mn 0.2] In Comparative Examples 4 to 6, 7 to 9, 10 to 12, and 13 to 15 using O2, the high-temperature cycle characteristics were not improved even when the first and second additives were used in combination. In particular, it can be confirmed that Comparative Examples 7 and 13, which used positive electrodes using the same positive electrode active material but used a combination of the first and second additives, showed a lower capacity retention rate than Comparative Examples 8 to 9, 14 to 15, which added only the first or second additive. In addition, it can be confirmed that Comparative Example 16, which used 1,3-propane sultone as the first additive, showed a lower high-temperature cycle performance. Experimental Example 2: High-Temperature Storage Performance Test The lithium secondary batteries manufactured in Examples 1 to 8 and Comparative Examples 1 to 16 above were charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C and discharged to 2.5 V under CC, 0.33 C conditions to perform initial charge / discharge, and then charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C and stored at 60°C for 20 weeks. (1) Capacity retention rate After 20 weeks of storage, the lithium secondary battery was charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C and discharged to 2.5 V under CC, 0.33 C to measure the capacity during discharge. The capacity retention rate was evaluated according to the following formula, and the results are shown in Table 3 below. Capacity retention (%) = (Discharge capacity after 20 weeks of storage / Initial discharge capacity) Х 100 (2) Resistance increase rate After the initial charge and discharge above, the capacity was checked at room temperature, and then charged to 50% SOC based on the discharge capacity, discharged for 10 seconds with a current of 2.5 C, and the resistance was measured based on the difference in voltage drop at this time, which was used as the initial resistance. After 20 weeks of storage at 60°C, the resistance was measured using the same method, which was used as the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 3 below. Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) Х 100 Capacity retention rate (%) Resistance increase rate (%) Example 18818 Example 28619 Example 38721 Example 48721 Example 58620 Example 68821 Example 78720 Example 88719 Comparative example 15040 Comparative example 25236 Comparative example 35035 Comparative example 44258 Comparative example 54855 Comparative example 64856 Comparative example 76650 Comparative example 86447 Comparative example 96454 Comparative example 106844 Comparative example 116549 Comparative example 126646 Comparative example 135145 Comparative example 145343 Comparative example 155344 Comparative example 165049 Referring to Table 3 above, Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2 as a cathode active material and a non-aqueous electrolyte including the first additive and the second additive as additives, it can be confirmed that the lithium secondary batteries of Examples 1 to 8 have a higher capacity retention rate and a lower resistance increase rate during high-temperature storage than the Comparative Examples 1 to 16. Specifically, Li[Ni 0.6 Co 0.1 Mn 0.3 ]O2 instead of Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2, Li[Ni 0.86 Co 0.05 Mn 0.08 Al 0.01 ]O 2, LiCoO 2, Li[Ni 0.6 Co 0.2 Mn 0.2 ]O2, Li[Ni0.6 Co 0.2 Mn 0.2 ] In Comparative Examples 4 to 6, 7 to 9, 10 to 12, and 13 to 15 using O2, the high-temperature cycle characteristics were not improved even when the first and second additives were used in combination. In particular, it can be confirmed that Comparative Examples 4 and 13, which used positive electrodes using the same positive electrode active material and used the first and second additives in combination, had lower effects than Comparative Examples 5 to 6 and 14 to 15, which added only the first or second additive. In addition, it can be confirmed that Comparative Example 16, which used 1,3-propane sultone as the first additive, had lower high-temperature storage performance. Experimental Example 3: Hot Box Test The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 16 manufactured above were charged to 4.4 V, 0.05 C under CC / CV, 0.1 C conditions at 45°C under a pressure of 50 kgf using an electrochemical charger / discharger, and then discharged to 2.5 V under CC, 0.1 C conditions to activate them. Thereafter, the activated lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 16 were charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C to fully charge them to 100% SOC. Each fully charged lithium secondary battery was placed in a hot box chamber at room temperature, heated to 140°C at a heating rate of 5°C / min, and left for 1 hour to measure the temperature change of the battery. If no thermal runaway or ignition occurred during the test, it was marked as Pass, and if thermal runaway and / or ignition occurred, it was marked as Fail. The results are shown in Table 4 below. Hot Box Test ResultsExample 1PassExample 2PassExample 3PassExample 4PassExample 5PassExample 6PassExample 7PassExample 8PassComparison Example 1FailComparison Example 2FailComparison Example 3FailComparison Example 4FailComparison Example 5FailComparison Example 6FailComparison Example 7FailComparison Example 8FailComparison Example 9FailComparison Example 10FailComparison Example 11FailComparison Example 12FailComparison Example 13FailComparison Example 14FailComparison Example 15FailComparison Example 16Fail Referring to Table 4 above, Li[Ni 0.6 Co 0.1 Mn 0.3 ]The lithium secondary batteries of Examples 1 to 8, which combined a positive electrode including O2 as a positive electrode active material and a non-aqueous electrolyte including a first additive and a second additive as additives, did not ignite as a result of the hot box test, but the lithium secondary batteries of Comparative Examples 1 to 16 were confirmed to ignite as a result of the hot box test.

Claims

1. Containing a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte; The above positive electrode includes a positive electrode active material, The above positive electrode active material includes a lithium nickel-based oxide represented by the following chemical formula 1, The above non-aqueous electrolyte comprises a lithium salt, an organic solvent, a first additive and a second additive, The above first additive comprises a compound represented by the following chemical formula A, A lithium secondary battery, wherein the second additive comprises a compound represented by the following chemical formula C. [Chemical Formula 1] Li 1+x [Ni a Co b Mr c M 1 d ]O2 In the above chemical formula 1, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0 <b<0.2, 0<c≤0.4, 0≤d≤0.2이고, M 1 is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. [Chemical Formula A] In the above chemical formula A, n is 1 or 2, L1 and L2 are each independently a direct bond or a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, R1 and R2 are each independently a substituent represented by the following chemical formula B, [Chemical Formula B] In the above chemical formula B, m is 1 or 2, X1 and X2 are each independently -O- or -C(R 31 )(R 32 )-but at least one of the above X1 and X2 is -O-, R 31 Inland R 36 are each independently hydrogen, an alkyl group having 1 to 6 carbon atoms, -C(=O)-R4 or -R5-OC(=O)-R6, The above R4 and R6 are each independently a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, The above R5 is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms, The substituents of the above L1, L2, R4, R5 and R6 are each independently at least one selected from the group consisting of deuterium, -F, -Cl, -Br, -I, -CN, -NO2 and -SO3, * is the position where it binds to L1 or L2, If both L1 and L2 are direct bonds, then R1 and R2 are not CS-7 at the same time, When L1 and L2 are both methylene groups and n is 2, R1 and R2 are not CS-2 at the same time. [Chemical Formula C] In the above chemical formula C, R7 comprises a halogen, a nitrile group, a propargyl group, an ester group, an ether group, a ketone group, a carboxyl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alkoxy group, a boron group, a borate group, an isocyanate group, an isothiocyanate group, a silyl group, a siloxane group, a sulfone group, a sulfonate group, a sulfate group, or a combination of two or more thereof, p is an integer selected from 0 to 6.

2. In paragraph 1, A lithium secondary battery, wherein in the chemical formula 1, a / b is 3.2 to 9.

0.

3. In paragraph 1, A lithium secondary battery, wherein in the above chemical formula 1, a / c is 1.5 to 2.

8.

4. In paragraph 1, In the above chemical formula 1, 0≤x≤0.2, a+b+c+d = 1, 0.55≤a≤0.65, 0 <b≤0.15, 0.2≤c≤0.4, 0≤d≤0.1, 4.0≤a / b≤8.5, 1.6≤a / c≤2.6인, 리튬 이차전지.

5. In paragraph 1, A lithium secondary battery, wherein in the above chemical formula A, R1 and R2 are each independently a substituent selected from the group consisting of CS-1 to CS-15.

6. In paragraph 5, A lithium secondary battery, wherein the above R1 and R2 are each independently a substituent selected from the group consisting of CS-1, CS-2, CS-5, CS-8, CS-10, and CS-11.

7. In paragraph 1, A lithium secondary battery, wherein the above L1 and L2 are methylene groups.

8. In paragraph 1, A lithium secondary battery, wherein the compound represented by the above chemical formula A comprises at least one selected from the group consisting of compounds A-1 to A-18.

9. In paragraph 1, A lithium secondary battery, wherein the compound represented by the above chemical formula C comprises at least one selected from the group consisting of a compound represented by the following chemical formula C-1 and a compound represented by the following chemical formula C-2. [Chemical Formula C-1] [Chemical Formula C-2] In the above chemical formulas C-1 and C-2, R7 is as defined in the above chemical formula C.

10. In paragraph 1, A lithium secondary battery, wherein the compound represented by the above chemical formula C comprises at least one selected from the group consisting of compounds represented by the following chemical formulas C-3 to C-11. [Chemical Formula C-3] [Chemical Formula C-4] [Chemical Formula C-5] [Chemical Formula C-6] [Chemical Formula C-7] [Chemical Formula C-8] [Chemical Formula C-9] [Chemical Formula C-10] [Chemical Formula C-11] 11. In paragraph 1, A lithium secondary battery, wherein the weight ratio of the first additive and the second additive is 12:1 to 0.5:

1.

12. In paragraph 1, A lithium secondary battery, wherein the first additive is included in an amount of 0.01% to 12% by weight based on the total weight of the non-aqueous electrolyte.

13. In paragraph 1, A lithium secondary battery, wherein the second additive is included in an amount of 0.01 wt% to 6 wt% based on the total weight of the non-aqueous electrolyte.

14. In paragraph 1, The above lithium secondary battery is a lithium secondary battery having a charge cut-off voltage of 4.3 V or higher when operated.

15. In paragraph 1, The above lithium secondary battery is a lithium secondary battery having a nominal voltage of 3.68 V or higher.

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