Lithium secondary battery

Abstract

The present invention relates to 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 transition metal oxide represented by chemical formula A below, the non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, the organic solvent comprises a linear carbonate, the linear carbonate comprises diethyl carbonate, the diethyl carbonate is included in an amount of 5 vol % to 25 vol % with respect to the total volume of the organic solvent, and the additive comprises lithium bis(oxalato)borate. [Chemical formula A] Li1+x[NiaCobMncM1 d]O2+w In chemical formula A, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0≤b≤0.15, c=1-a-b-d, 0≤d≤0.1, 0≤b / a≤0.2, 1≤a / c≤3, 0≤w≤1, and M1 is at least one selected from among 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.

Description

Lithium secondary battery The present invention relates to a lithium secondary battery. 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 computers, 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 cathode including a cathode active material, an anode including a cathode 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 cathode 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 oxide can be used as the cathode active material. Meanwhile, in recent years, lithium nickel-cobalt-manganese composite transition metal oxides with a nickel content of 80 mol% or more relative to the transition metal have been mainly studied in terms of increasing the energy density of the anode. However, there is a problem that the thermal stability of the anode deteriorates when the nickel content of the lithium nickel-cobalt-manganese composite transition metal oxide is increased. To prevent these problems, when the nickel content in the lithium nickel-cobalt-manganese composite transition metal oxide is lowered, the driving voltage must be increased to achieve the required energy density. However, when driving at such high voltage, the problems of electrolyte side reactions at the anode, decreased high-temperature durability, and increased resistance are aggravated. One object of the present invention is to solve the above-described problems, and to provide a lithium secondary battery using a lithium transition metal oxide having a nickel content as a cathode active material reduced to a specific level, in which the life performance and storage performance are improved when driven at high voltage, and an increase in resistance can be significantly prevented. [1] The present invention provides a lithium secondary battery comprising: a positive electrode; an anode; 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 transition metal oxide represented by the following chemical formula A, and wherein the non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, wherein the organic solvent comprises a linear carbonate, wherein the linear carbonate comprises diethyl carbonate, wherein the diethyl carbonate is contained in an amount of 5 vol% to 25 vol% based on the total volume of the organic solvent, and wherein the additive comprises lithium bis(oxalato)borate. [Chemical Formula A] Li 1+x [Ni a Co b Mn c M 1 d ]O 2+w In the above chemical formula A, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0≤b≤0.15, c=1-abd, 0≤d≤0.1, 0≤b / a≤0.2, 1≤a / c≤3, 0≤w≤1, and 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. [2] The present invention provides a lithium secondary battery having an operating voltage of 4.3 V or higher in the above [1]. [3] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [2], the additive further includes a compound represented by the following chemical formula 1. [Chemical Formula 1] In the above chemical formula 1, R a1 , R b1 and R c1are each independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN, and L 21 is an alkylene group having 1 to 3 carbon atoms. [4] The present invention provides a lithium secondary battery, wherein the non-aqueous electrolyte comprises 0.01 wt% to 10 wt% of the lithium bis(oxalato)borate in at least one of the above [1] to [3]. [5] The present invention provides a lithium secondary battery, wherein in at least one of the above [1] to [4], the diethyl carbonate is contained in an amount of 7 to 15 volume% based on the total volume of the organic solvent. [6] The present invention provides a lithium secondary battery according to at least one of the above [1] to [5], wherein the organic solvent further includes a cyclic carbonate. [7] The present invention provides a lithium secondary battery according to at least one of the above [1] to [6], wherein the cyclic carbonate further includes ethylene carbonate. [8] The present invention provides a lithium secondary battery according to at least one of the above [1] to [7], wherein the volume ratio of the cyclic carbonate and the linear carbonate is 5:95 to 40:60. [9] The present invention provides a lithium secondary battery, wherein in one or more of the above [1] to [8], the additive further includes at least one selected from the group consisting of coumarine, fluoroethylene carbonate, vinylethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, lithium difluoro phosphate (LiDFP), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiDFOB), Tris(trimethylsilyl) Phosphate (TMSPi), and Tris(trimethylsilyl) Phosphite (TMSPi).

[0010] The present invention provides a lithium secondary battery, wherein in one or more of the above [1] to [9], the lithium salt is included in the non-aqueous electrolyte at a molar concentration of 0.5 M to 5.0 M.

[0011] The present invention provides a lithium secondary battery in which, in one or more of the above [1] to

[0010] , the positive electrode active material is in the form of a single particle consisting of one single nodule or a quasi-single particle complex consisting of 30 or fewer nodules.

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

[0011] , in the chemical formula A, a / (b × c) is 18 to 50. The lithium secondary battery of the present invention is characterized in that it uses a lithium transition metal oxide in which nickel, cobalt, and manganese are adjusted to a specific content range as a cathode active material, and the non-aqueous electrolyte contains diethyl carbonate as a linear carbonate in a specific content and lithium bis(oxalato)borate as an additive. The lithium secondary battery according to the present invention has improved life performance and storage performance when driven at high voltage, and can significantly prevent an increase in resistance. The 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 having 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 in order to explain his or her own invention in the best manner. It should be understood that the terms “comprise,” “include,” or “have,” as used herein, are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not exclude in advance 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 specifically stated, "*" in the present invention means a connected portion (bonding site) between terminals of identical or different atoms or chemical formulas. In addition, in the description of "carbon atoms a to b" in the present specification, "a" and "b" represent the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "an alkyl group having 1 to 5 carbon atoms" refers to 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 the present specification, both the alkyl group and the aryl group may be substituted or unsubstituted. The above "substitution" means, unless otherwise defined, that at least one hydrogen bonded to carbon is replaced with 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, a halogen atom, an aryl group having 2 to 20 carbon atoms, a cycloalkyl ... It means substituted with a heteroaryl group having 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, etc. In this specification, the average particle diameter (D 50 ) can be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D 50) can be measured, for example, using a laser diffraction method. The laser diffraction method can generally measure particle diameters from the submicron range to several mm, and can obtain results with high reproducibility and high resolution. In this specification, the BET specific surface area is measured by the BET method, and specifically, can be calculated by obtaining the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mini II of BEL Japan. Hereinafter, the present invention will be described in more detail. Lithium secondary battery The present invention relates to a lithium secondary battery. A lithium secondary battery according to the present invention comprises: 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, wherein the cathode active material comprises a lithium transition metal oxide represented by the following chemical formula A, and wherein the non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, wherein the organic solvent comprises a linear carbonate, wherein the linear carbonate comprises diethyl carbonate, wherein the diethyl carbonate is contained in an amount of 5 vol% to 25 vol% based on the total volume of the organic solvent, and wherein the additive comprises lithium bis(oxalato)borate. [Chemical Formula A] Li 1+x [Ni a Co b Mn c M 1 d ]O 2+w In the above chemical formula A, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0≤b≤0.15, c=1-abd, 0≤d≤0.1, b / a≤0.2, 1≤a / c≤3, 0≤w≤1, and 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. The lithium secondary battery includes a positive electrode; an negative electrode; a separator; and a non-aqueous electrolyte. Specifically, the lithium secondary battery includes a positive electrode; an negative electrode opposing the positive electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte. The lithium secondary battery can be manufactured by housing an electrode assembly including the positive electrode; an negative electrode opposing the positive electrode; and a separator interposed between the positive electrode and the negative electrode in a battery case, and then injecting a non-aqueous electrolyte. (1) Bipolar The above positive electrode contains a positive electrode active material. The above positive electrode active material includes a lithium transition metal oxide represented by the following chemical formula A. [Chemical Formula A] Li 1+x [Ni a Co b Mn c M 1 d ]O 2+w In the above chemical formula A, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0≤b≤0.15, c=1-abd, 0≤d≤0.1, 0≤b / a≤0.2, 1≤a / c≤3, 0≤w≤1, and 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 lithium transition metal oxide represented by the above chemical formula A is distinguished from, for example, a high-nickel lithium transition metal oxide having a Ni content exceeding 70 mol% relative to metals other than lithium. The high-nickel lithium transition metal oxide is undesirable in that its thermal stability is reduced due to the large amount of nickel contained therein. Meanwhile, since the compound represented by the above chemical formula A has a lower nickel content than the high-nickel lithium transition metal oxide, it needs to be driven at a high voltage (for example, 4.35 V or higher) to increase the energy density of the positive electrode. However, during such high-voltage driving, the positive electrode electrolyte side reaction is intensified, so that the life performance and storage performance are greatly reduced, and the high-temperature durability is reduced, which aggravates the problem of increased resistance. This is because the oxidation and decomposition of organic solvents (such as ethylene carbonate) are promoted during high-voltage driving, generating carbon dioxide (CO2), or because Lewis acids such as HF and PF5 formed by the decomposition of lithium salts (such as LiPF6) decompose the positive electrode film, dissolving the transition metal of the positive electrode active material, and causing structural collapse. According to the present invention, in order to achieve both high energy density and excellent life performance and storage performance, a lithium secondary battery using a cathode active material including a lithium transition metal oxide represented by the chemical formula A is characterized in that the non-aqueous electrolyte contains diethyl carbonate as a linear carbonate in a specific content and lithium bis(oxalato)borate as an additive. The diethyl carbonate is a solvent that is relatively stable in both oxidation and reduction, and as described below, when used in a specific content, decomposition of an organic solvent or a non-aqueous electrolyte can be prevented. In addition, when the diethyl carbonate and lithium bis(oxalato)borate are used in combination, the cathode interface can be stabilized or a durable cathode film can be formed. As a result, it is possible to implement a lithium secondary battery having a high energy density, remarkably excellent life performance and storage performance, and a low level of resistance increase rate. The effect of improving battery performance at high voltage by applying the above non-aqueous electrolyte can be exhibited when a cathode active material including a lithium transition metal oxide having chemical formula A is used. For example, Li[Ni 0.8 Co 0.1 Mn 0.1 ]O2, etc. In the case of high nickel lithium transition metal oxides, the ratio 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 therefore it is difficult to express the performance improvement effect through the organic solvent and additive. In addition, Li[Ni 0.8 Co 0.1 Mn 0.1]O2, etc., 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 the additive. In addition, Li[Ni 0.6 Co 0.2 Mn 0.2 ] In the case of lithium transition metal oxides that do not satisfy the chemical formula A, such as O2, 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 cathode film using an additive. Accordingly, in the case of a compound other than the compound represented by the chemical formula A, it is difficult to improve the desired life performance and storage performance even if the non-aqueous electrolyte according to the present invention is used. In the above chemical formula A, x can be 0≤x≤0.5, specifically 0≤x≤0.2. In the above chemical formula A, 0.5≤a≤0.7, specifically 0.55≤a≤0.65. In the chemical formula A, 0≤b≤0.15. b corresponds to the molar percentage of Co among the metals excluding lithium in the lithium transition metal oxide represented by the chemical formula A. According to the present invention, by lowering the Co content, there is a cost advantage, and by relatively increasing the proportion of Mn, the structural stability of the positive electrode active material can be improved. Specifically, in the chemical formula A, 0≤b≤0.1 may be satisfied. In the chemical formula A, 0≤b / a≤0.2. If b / a exceeds 0.2, the ratio of Co in the transition metal is very high, so that the irreversibility in the structure increases, making it difficult to exhibit the performance improvement effect by forming an anode film through an additive. Specifically, in the chemical formula A, 0.05≤b / a≤0.2 may be satisfied. In the chemical formula A, c = 1-abd, and 1 ≤ a / c ≤ 3. c corresponds to the molar percentage of Mn among the metals excluding lithium in the lithium transition metal oxide represented by the chemical formula A, and according to the present invention, the molar ratio of Ni to Mn is adjusted to 1 ≤ a / c ≤ 3, thereby improving the structural stability of the cathode active material. Specifically, it may be 1.5 ≤ a / c ≤ 2.5. In the above chemical formula A, M 1 can be understood as a doping element of a lithium transition metal 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≤0.1, specifically, 0≤d≤0.05. In the above chemical formula A, a / (b × c) may be 18 to 50, specifically 18 to 40, and more specifically 20 to 35. When within the above range, the contents of nickel, cobalt, and manganese in the chemical formula A are harmoniously adjusted, thereby enhancing the performance improvement effect by forming a positive electrode film through an additive and simultaneously improving the structural stability of the positive electrode active material. The above positive electrode active material may be in the form of particles. Specifically, the positive electrode active material is in the form of a single particle composed of one single nodule or a quasi-single particle which is a complex of 30 or fewer nodules, and specifically, the positive electrode active material may be a quasi-single particle which is a complex of 2 to 20 nodules, more specifically 2 to 10 nodules, or may be in a form including them. In this case, when manufacturing an electrode of the positive electrode active material, particle breakage is prevented, and occurrence of internal cracks due to volume expansion / contraction of the nodules during charge / discharge is prevented, so that the high-temperature life characteristics and high-temperature storage characteristics can be improved. The average particle diameter (D) of the above positive electrode active material 50) may be 1 ㎛ to 10 ㎛, specifically 2 ㎛ to 8 ㎛, more specifically 3 ㎛ to 7 ㎛, even more specifically 3 ㎛ to 5 ㎛, and even more specifically 3.5 ㎛ to 4.5 ㎛. When the above range is satisfied, the processability during electrode manufacturing may be excellent, the electrolyte impregnation property may be increased, so that the electrochemical properties may be increased, and the resistance may be reduced and the output characteristics may be improved. The specific surface area of ​​the above positive electrode active material is 0.1 m 2 / g to 3.0m 2 / g, specifically 0.3m 2 / g to 2.5m 2 / g, more specifically 0.4m 2 / g to 1.8m 2 / g, more specifically 0.5m 2 / g to 1.0m 2 / g, more specifically 0.7m 2 / g to 0.9m 2 / g. When the above range is satisfied, the rolling characteristics of the electrode can be improved, and particle breakage can be reduced, thereby suppressing side reactions with the electrolyte. The above 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. In this case, 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 can typically have a thickness of 3 to 500 μm. The above-mentioned positive electrode current collector may form fine irregularities on the surface to strengthen the bonding strength of the positive electrode active material. For example, the above-mentioned positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. The above positive electrode active material layer can be disposed on at least one side of the positive electrode current collector, specifically, on one side or both sides of the positive electrode current collector. The above-mentioned positive electrode active material may be included in the positive electrode active material layer at 80 to 99 wt%, preferably 92 to 98.5 wt%, taking into account sufficient capacity of the positive electrode active material. Description of other positive electrode active materials is omitted as it has been described above. 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, polyvinyl pyrrolidone, 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 a chemical change. 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, the positive electrode conductive material may include carbon nanotubes in terms of improving conductivity. The above-mentioned conductive material 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 electrical conductivity. The thickness of the above positive electrode active material layer may be 30 ㎛ to 400 ㎛, preferably 40 ㎛ to 200 ㎛. The above positive electrode can be manufactured by coating a positive electrode slurry including a positive electrode active material and optionally a binder, a conductive material, and a solvent for forming a positive electrode slurry on the positive electrode current collector, and then drying and rolling. The solvent for forming the positive electrode slurry may include an organic solvent such as NMP (N-methyl-2-pyrrolidone). The solid content of the positive electrode slurry may be 40 wt% to 90 wt%, specifically 50 wt% to 80 wt%. (2) Cathode The above cathode can be opposed to the above anode. The above negative electrode includes a negative electrode active material. The above negative active material is a material capable of reversibly inserting / deleting lithium ions, and may include at least one selected from the group consisting of a carbon-based active material, a (semi)metal-based active material, and lithium metal, and specifically may include at least one selected from a carbon-based active material and a (semi)metal-based active material. The above carbon-based active material may include at least one selected from the group consisting of graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include graphite. The graphite may be, for example, at least one of artificial graphite and natural graphite. The average particle diameter (D) of the above carbon-based active material 50 ) may be 10 ㎛ to 30 ㎛, preferably 15 ㎛ to 25 ㎛, in order to ensure structural stability during charging and discharging and reduce side reactions with the electrolyte. Specifically, the (semi)metal-based active material may include at least one (semi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium and at least one (semi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (semi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); lithium vanadium oxide; and the like. More specifically, the (semi)metal-based active material may include a silicon-based active material. The above silicon-based active material is SiO xIt may include a compound represented by (0≤x<2). In the case of SiO2, since it does not react with lithium ions and thus cannot store lithium, it is preferable that x is within the above range, and more preferably, the silicon-based active material may be SiO. The average particle diameter (D) of the above silicon-based active material 50 ) may be 1 ㎛ to 30 ㎛, preferably 2 ㎛ to 15 ㎛, in order to reduce side reactions with the electrolyte while ensuring structural stability during charging and discharging. The above 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. In this case, 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. Specifically, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. The above negative electrode collector may typically have a thickness of 3 to 500 μm. The above negative electrode current collector may form fine irregularities on the surface to strengthen the bonding strength of the negative electrode active material. For example, the above negative electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc. The above negative electrode active material layer may be disposed on at least one surface of the negative electrode current collector, specifically, one surface or both surfaces of the negative electrode current collector. The above negative active material may be included in the negative active material layer in an amount of 60 to 99 wt%, preferably 75 to 95 wt%. Description of other positive electrode active materials is omitted as it has been described above. The above negative electrode active material layer may further include a binder and / or a conductive material together with the negative electrode active material. The above binder is used to improve the performance of the battery by improving the adhesion between the negative electrode active material layer and the negative electrode current collector, and may include, for example, at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, and materials in which hydrogens of these are substituted with Li, Na or Ca, etc., and also may include various copolymers thereof. may include: The above binder may be included in the negative electrode active material layer in an amount of 0.5 wt% to 10 wt%, preferably 1 wt% to 5 wt%. The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, 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; fluorocarbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. can be used. The above-mentioned conductive agent may be included in the negative electrode active material layer in an amount of 0.5 wt% to 10 wt%, preferably 1 wt% to 5 wt%. The thickness of the above negative active material layer may be 10 µm to 200 µm, preferably 20 µm to 150 µm. The above negative electrode can be manufactured by coating a negative electrode slurry including a negative electrode active material, a binder, a conductive material and / or a solvent for forming a negative electrode slurry on at least one surface of a negative electrode current collector, and then drying and rolling. The solvent for forming the negative electrode slurry may include at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate dispersion of the negative electrode active material, binder, and / or conductive agent, for example. The solid content of the negative electrode slurry may be 30 wt% to 80 wt%, specifically 40 wt% to 70 wt%. (3) Membrane The above separator may be interposed between the anode and the cathode. In addition, as a separator, a conventional porous polymer film that has been conventionally used as a separator, 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 to secure heat resistance or mechanical strength may be used, 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 and an 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 salts are 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 transference number and the degree of dissociation of lithium ions can be improved, thereby improving the output characteristics of the battery. 2) Organic solvent The above organic solvent 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 charge / discharge process of the secondary battery can be minimized. The above organic solvent comprises a linear carbonate. The above linear carbonate comprises diethyl carbonate. The above diethyl carbonate is a relatively stable solvent in both oxidation and reduction, so that oxidative decomposition of organic solvents is suppressed and gas generation due to electrolyte side reactions can be suppressed. The above diethyl carbonate is included in an amount of 5 to 25 vol% based on the volume of the organic solvent. If the diethyl carbonate is used in an amount less than 5 vol% based on the volume of the organic solvent, the desired effect of inhibiting the decomposition of the organic solvent and reducing gas generation cannot be achieved. If the diethyl carbonate is used in an amount exceeding 25 vol% based on the volume of the organic solvent, the electrolyte properties become poor and the resistance increases due to a decrease in ionic conductivity and an increase in viscosity. In addition, the effect according to the specific content range of the diethyl carbonate is expressed when combined with the additive described below. For example, when the lithium bis(oxalato)borate is not used as an additive, even if the diethyl carbonate is used in an amount of 5 to 25 vol% based on the volume of the organic solvent, a uniform and thin film cannot be formed on the positive and negative electrode interfaces, so the durability deteriorates, and the desired effect of simultaneously improving the life performance, storage performance, and resistance reduction cannot be achieved. The above diethyl carbonate may be included specifically in an amount of 7 vol% to 20 vol%, more specifically in an amount of 7 vol% to 15 vol%, and even more specifically in an amount of 7 vol% to 12 vol%, based on the volume of the organic solvent. The above linear carbonate may, in addition to the diethyl carbonate, include at least one selected from the group consisting of dimethyl carbonate (DMC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, in terms of contributing to low viscosity and low dielectric constant, and more specifically, may further include ethyl methyl carbonate (EMC). If the linear carbonate includes diethyl carbonate and ethyl methyl carbonate, the volume ratio of diethyl carbonate and ethyl methyl carbonate may be 5:95 to 50:50, specifically 10:90 to 30:70, and more specifically 10:90 to 20:80. The organic solvent may further include a cyclic carbonate. The cyclic carbonate is a high-viscosity organic solvent with a high dielectric constant, which can easily dissociate lithium salts in the electrolyte. The cyclic carbonate may cause side reactions such as collapse of the cathode active material or generation of HF during high-voltage driving or when driven at high voltage, thereby causing gas generation. However, by using diethyl carbonate as the organic solvent described above in a specific content and forming a solid film by using a specific additive, this problem can be significantly prevented. The above cyclic carbonate 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 organic solvent selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically, may include ethylene carbonate (EC). When the organic solvent contains a cyclic carbonate, the cyclic carbonate and the linear carbonate can be mixed in a volume ratio of 5:95 to 40:60, specifically, a volume ratio of 10:90 to 35:65. When the mixing ratio of the cyclic carbonate and the linear carbonate satisfies the above range, high dielectric constant and low viscosity characteristics can be simultaneously satisfied, and excellent ion conductivity characteristics can be implemented. Meanwhile, the organic solvent may be used without limitation by adding an organic solvent commonly used in a non-aqueous electrolyte as needed. For example, at least one organic solvent from among an ester-based organic solvent, an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent may be additionally included. The above ester organic solvent may include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone. 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-mentioned glyme 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. 4) Additives The above non-aqueous electrolyte contains an additive. The above additive includes lithium bis(oxalato)borate (LiBOB). The above lithium bis(oxalato)borate can form a film on the positive electrode when the lithium secondary battery is driven at a high voltage (e.g., 4.3 V or higher). The lithium bis(oxalato)borate can form a highly durable positive electrode film to stabilize the positive electrode interface, or act as a Lewis acid to prevent the attack of HF. Therefore, when combined with the positive electrode active material (containing the compound represented by the chemical formula A) according to the present invention, which requires high voltage operation to increase energy density, it is possible to significantly prevent electrolyte side reactions, and to improve high levels of life performance and storage performance. On the other hand, when a high-nickel lithium transition metal oxide is used as the positive electrode active material, for example, since the lithium secondary battery is driven at a low operation voltage (e.g., 4.2 V), there is a high possibility that the additive will form a film on the negative electrode rather than the positive electrode, and therefore the purpose of the present invention to prevent electrolyte side reactions on the positive electrode cannot be sufficiently achieved. Meanwhile, the improvement in the durability of the positive electrode film and the stabilization effect of the positive electrode interface by using the lithium bis(oxalato)borate can be realized by using the above-described diethyl carbonate in a specific content. If the diethyl carbonate is not used in an amount of 5 to 25 vol% based on the volume of the organic solvent, even if the lithium bis(oxalato)borate is used as an additive, a problem occurs in which long-term high-voltage durability cannot be secured, and thus the desired simultaneous improvement effects of life performance, storage performance, and resistance reduction effect cannot be achieved. The lithium bis(oxalato)borate may be included in the non-aqueous electrolyte in an amount of 0.01 wt% to 10 wt%, specifically 0.1 wt% to 5 wt%, more specifically 0.05 wt% to 2.5 wt%, more specifically 0.1 wt% to 1 wt%, and specifically 0.3 wt% to 1 wt%, and when present in the above range, the aforementioned effect of improving the life performance and storage performance of the secondary battery is exhibited, which is preferable in that an increase in resistance due to excessive use of additives can be prevented. The above additive may further include a compound represented by the following chemical formula 1. In this case, the effect of preventing decomposition of the anode film by HF and the effect of enhancing the durability of the anode film can be improved to a desirable level, and in particular, it is desirable in that excellent improvement of the gas reduction effect and resistance reduction effect is possible. [Chemical Formula 1] In the above chemical formula 1, R a1 , R b1 and R c1 are each independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN, and L 21 is an alkylene group having 1 to 3 carbon atoms. In the above chemical formula 1, R a1 , R b1 and R c1are each independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN, and specifically, they can each independently be hydrogen or an alkyl group having 1 to 2 carbon atoms, and more specifically, they can each be hydrogen. When within the above range, the compound represented by the chemical formula 1 has an imidazole group included therein that suppresses the generation of Lewis acids such as HF and PF5, and at the same time, the nitrogen element acts as a Lewis base to remove the Lewis acid generated in the electrolyte, and contains a propargyl functional group that is easily reduced at the terminal, so that an electrode film having high passivation ability can be formed, thereby preventing additional reduction decomposition reactions caused by instability of the film, and improving the high-temperature durability of the electrode. In the above chemical formula 1, L 21 may be an alkylene group having 1 to 3 carbon atoms, specifically a methylene group or an ethylene group, and more specifically a methylene group. Specifically, the compound represented by the chemical formula 1 may include a compound represented by the following chemical formula 1-1. [Chemical Formula 1-1] When the above additive includes lithium bis(oxalato)borate and a compound represented by the above chemical formula 1, the compound represented by the above chemical formula 1 may be included in an amount of specifically 0.05 wt% to 2.5 wt%, more specifically 0.1 wt% to 1 wt%. The above additive may further include additional additives. The above additive may further include at least one selected from the group consisting of coumarine, fluoroethylene carbonate, vinylethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, lithium difluoro phosphate (LiDFP), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiDFOB), Tris(trimethylsilyl) Phosphate (TMSPa), and Tris(trimethylsilyl) Phosphite (TMSPi). The above additional additive may be included in the non-aqueous electrolyte in an amount of 0.1 wt% to 15 wt%. The operating voltage of the lithium secondary battery of the present invention may be 4.3 V or higher, specifically 4.35 V or higher. The lithium secondary battery of the present invention can achieve excellent energy density and improved life performance and storage performance at a high operating voltage by combining the above-described positive electrode and non-aqueous electrolyte. There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be in the shape of a cylinder, a square, a pouch, or a coin using a can. Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are merely examples to help understand the present invention and do not limit the scope of the present invention. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present description, and it is natural that such changes and modifications fall within the scope of the appended patent claims. Examples and Comparative Examples Example 1 (Manufacture of non-aqueous electrolyte) As an organic solvent, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:70:10 was used. A non-aqueous electrolyte was prepared by adding LiPF6, lithium bis(oxalato)borate as a lithium salt to the above organic solvent. The above LiPF6 was included in the non-aqueous electrolyte at a molar concentration of 1.2 M. Lithium bis(oxalato)borate was included in the non-aqueous electrolyte at 0.5 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) as a solvent at a weight ratio of 97.0:1.2:1.8 to prepare a cathode slurry (solid content 72 wt%). The cathode slurry was applied to one surface of a cathode current collector (Al thin film) having a thickness of 15 μm, dried and roll pressed to form a cathode active material layer (thickness: 137 μm), which was used as a cathode. The cathode active material is in the form of a single particle, and has an average particle diameter (D 50 ) is 3.9㎛ and the BET surface area is 0.86m 2 / g was. Negative electrode slurry (solid content 53 wt%) was prepared by adding negative electrode active material (graphite): conductive material (carbon black): binder (styrene-butadiene rubber and carboxymethyl cellulose) to distilled water as a solvent in a weight ratio of 97.4:0.5:2.1. The negative electrode slurry was applied to one surface of a 15 ㎛ thick negative electrode current collector (Cu thin film), dried, and roll pressed to form a negative electrode active material layer (thickness: 176 ㎛), 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 lithium secondary battery. Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:65:15 was used as the organic solvent. Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by the chemical formula 1-1 was further included in the non-aqueous electrolyte in an amount of 0.5 wt%. Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80 was used as the organic solvent. Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) was used in a volume ratio of 20:78:2. Comparative Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) was used in a volume ratio of 20:40:30. Comparative Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) was used in a volume ratio of 20:70:10. Comparative Example 5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that lithium bis(oxalato)borate was not included in the non-aqueous electrolyte. Comparative Example 6 A lithium secondary battery was manufactured in the same manner as in Example 1, except that lithium bis(oxalato)borate was not included in the non-aqueous electrolyte and vinylene carbonate was added to the non-aqueous electrolyte in an amount of 0.5 wt%. Experimental example Experimental Example 1: High Temperature Cycle Performance - Resistance Increase Rate Evaluation The lithium secondary batteries manufactured in Examples 1 to 3 and Comparative Examples 1 to 6 above were charged to 4.35 V, 0.05 C at 45°C under CC / CV, 0.33 C conditions using an electrochemical charger / discharger, and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger / 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 pulse application. 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 1 below. Resistance Increase Rate (%) = (Resistance after 400 cycles - Initial resistance) / Initial resistance × 100 Experimental Example 2: High Temperature Cycle Performance - Volume Increase Rate Evaluation The lithium secondary batteries manufactured in Examples 1 to 3 and Comparative Examples 1 to 6 above were charged to 4.35 V, 0.05 C at 45°C under CC / CV, 0.33 C conditions using an electrochemical charger / discharger, and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. At this time, the volume of the lithium secondary battery before performing charge / discharge (initial volume) and the volume of the lithium secondary battery after 400 cycles were measured, and the volume increase rate was calculated using the following formula, and the results are shown in Table 1 below. Volume increase rate (%) = {(volume of lithium secondary battery after 400 cycles - initial volume) / (initial volume)} × 100 Experimental Example 1 Experimental Example 2 Resistance Increase Rate (%) Volume Increase Rate (%) Example 123.218.8 Example 224.516.7 Example 315.515.3 Comparative Example 130.732.4 Comparative Example 230.431.6 Comparative Example 331.115.9 Comparative Example 459.550.3 Comparative Example 548.337.7 Comparative Example 646.642.6 Referring to Table 1 above, it can be confirmed that the lithium secondary batteries of Examples 1 to 3, in which a positive electrode including a positive electrode active material including a lithium transition metal oxide represented by the chemical formula A; and a non-aqueous electrolyte including a specific content of diethyl carbonate as an organic solvent and lithium bis(oxalato)borate as an additive; are combined, the resistance increase rate and the volume increase rate are significantly reduced at the same time during high-voltage, high-temperature cycle charge / discharge compared to the cases of Comparative Examples 1 to 6. For reference Reference Example A: Li[Ni as a cathode active material 0.8 Co 0.1 Mn 0.1 ]When using O2 Reference Example 1A (1) Manufacturing of non-aqueous electrolyte The same non-aqueous electrolyte as that used in Example 1 was used. (2) Manufacturing of lithium secondary batteries Cathode active material (Li[Ni 0.8 Co 0.1 Mn 0.1]O2): Conductive agent (carbon nanotube): Binder (PVDF) was added to N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 96.78:1.20:2.02 to prepare a positive electrode mixture slurry (solid content 75.5 wt%). The positive electrode mixture slurry was applied to one surface of a positive electrode current collector (Al thin film), and dried and roll pressed to prepare a positive electrode. The positive electrode active material was in the form of secondary particles formed by assembling two or more primary particles. A negative electrode mixture slurry (solid content 26 wt%) was prepared by adding negative active material (natural graphite): conductive agent (carbon black): binder (styrene-butadiene rubber and carboxymethyl cellulose) to distilled water as a solvent in a weight ratio of 96.15:0.50:3.35. The negative electrode mixture slurry was applied to one surface of a 15 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare 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. Reference Example 2A A lithium secondary battery was manufactured in the same manner as in Reference Example 1A, except that the non-aqueous electrolyte used in Comparative Example 2 was used as the non-aqueous electrolyte. Reference Example 3A A lithium secondary battery was manufactured in the same manner as in Reference Example 1A, except that the non-aqueous electrolyte used in Comparative Example 3 was used as the non-aqueous electrolyte. Reference Example 4A A lithium secondary battery was manufactured in the same manner as Reference Example 1A, except that the non-aqueous electrolyte used in Comparative Example 5 was used as the non-aqueous electrolyte. Reference Experimental Example A-1: ​​High Temperature Cycle Performance - Resistance Increase Rate Evaluation The lithium secondary batteries of Reference Examples 1A to 4A manufactured above were charged to 4.2 V, 1 / 40 C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions at 45° C., and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger / 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 pulse application. 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 × 100 Reference Experimental Example A-2 The lithium secondary batteries of Reference Examples 1A to 4A manufactured above were charged to 4.2 V, 1 / 40 C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions at 45° C., and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. At this time, the volume of the lithium secondary battery before performing charge / discharge (initial volume) and the volume of the lithium secondary battery after 400 cycles were measured, and the volume increase rate was calculated using the following formula, and the results are shown in Table 2 below. Volume increase rate (%) = {(volume of lithium secondary battery after 400 cycles - initial volume) / (initial volume)} × 100 Reference Experimental Example A-1Reference Experimental Example A-2Resistance Increase Rate(%)Volume Increase Rate(%)Reference Example 1A27.96.1Reference Example 2A24.67.4Reference Example 3A32.55.9Reference Example 4A18.86.8 Referring to Table 2 above, Li[Ni 0.8 Co 0.1 Mn 0.1 ] In the case of using O2, it can be seen that the secondary battery of Reference Example 1A using a non-aqueous electrolyte containing a specific content of diethyl carbonate as an organic solvent and lithium bis(oxalato)borate as an additive has no resistance improvement effect and no improvement in the volume increase rate compared to the secondary batteries of Reference Examples 2A to 4A. Through this, it can be seen that the non-aqueous electrolyte according to the present invention can achieve the desired effect when a lithium transition metal oxide represented by chemical formula A is used as a positive electrode active material. Reference Example B: Li[Ni as a cathode active material 0.6 Co 0.2 Mn 0.2 ]When using O2 Reference Example 1B (1) Manufacturing of non-aqueous electrolyte The same non-aqueous electrolyte as that used in Example 1 was used. (2) Manufacturing of lithium secondary batteries Cathode active material (Li[Ni 0.6 Co 0.2 Mn 0.2 ]O2): Conductive agent (carbon nanotube): Binder (PVDF) was added to N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 96:2:2 to prepare a positive electrode mixture slurry (solid content 75 wt%). The positive electrode mixture slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 140 ㎛, and dried and roll pressed to prepare a positive electrode. The positive electrode active material was in the form of secondary particles formed by assembling two or more primary particles. A negative electrode mixture slurry (solid content 26 wt%) was prepared by adding negative active material (natural graphite): conductive agent (carbon black): binder (styrene-butadiene rubber and carboxymethyl cellulose) to distilled water as a solvent in a weight ratio of 96.15:0.50:3.35. The negative electrode mixture slurry was applied to one surface of a 15 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare 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. Reference Example 2B A lithium secondary battery was manufactured in the same manner as in Reference Example 1B, except that the non-aqueous electrolyte used in Comparative Example 2 was used as the non-aqueous electrolyte. Reference Example 3B A lithium secondary battery was manufactured in the same manner as Reference Example 1B, except that the non-aqueous electrolyte used in Comparative Example 3 was used as the non-aqueous electrolyte. Reference Example 4B A lithium secondary battery was manufactured in the same manner as Reference Example 1B, except that the non-aqueous electrolyte used in Comparative Example 5 was used as the non-aqueous electrolyte. Reference Experimental Example B-1: High Temperature Cycle Performance - Resistance Increase Rate Evaluation The lithium secondary batteries of Reference Examples 1B to 4B manufactured above were charged to 4.2 V, 1 / 40 C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions at 45° C., and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. After one cycle of charge and discharge, the discharge capacity after one cycle was measured using an electrochemical charger / 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 pulse application. 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 3 below. Resistance Increase Rate (%) = (Resistance after 400 cycles - Initial resistance) / Initial resistance × 100 Reference Experimental Example B-2 The lithium secondary batteries of Reference Examples 1B to 4B manufactured above were charged to 4.2 V, 1 / 40 C using an electrochemical charger / discharger under CC / CV, 0.33 C conditions at 45° C., and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, to perform 400 charge / discharge cycles. At this time, the volume of the lithium secondary battery before performing charge / discharge (initial volume) and the volume of the lithium secondary battery after 400 cycles were measured, and the volume increase rate was calculated using the following formula, and the results are shown in Table 3 below. Volume increase rate (%) = {(volume of lithium secondary battery after 400 cycles - initial volume) / (initial volume)} × 100 Reference Experimental Example B-1Reference Experimental Example B-2Resistance Increase Rate(%)Volume Increase Rate(%)Reference Example 1B16.64.3Reference Example 2B12.95.5Reference Example 3B19.34.1Reference Example 4B12.74.8 Referring to Table 3 above, Li[Ni 0.6 Co 0.2 Mn 0.2 ] In the case of using O2, it can be seen that the secondary battery of Reference Example 1B using a non-aqueous electrolyte containing a specific content of diethyl carbonate as an organic solvent and lithium bis(oxalato)borate as an additive has no resistance improvement effect and no improvement in the volume increase rate compared to the secondary batteries of Reference Examples 2B to 4B. Through this, it can be seen that the non-aqueous electrolyte according to the present invention can achieve the desired effect when a lithium transition metal oxide represented by chemical formula A is used as a positive electrode active material.

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 contains a positive electrode active material, The above positive electrode active material comprises a lithium transition metal oxide represented by the following chemical formula A, The above non-aqueous electrolyte comprises a lithium salt, an organic solvent and an additive, The organic solvent comprises a linear carbonate, The above linear carbonate includes diethyl carbonate, The above diethyl carbonate is contained in an amount of 5 to 25 volume% based on the total volume of the organic solvent, The above additive comprises lithium bis(oxalato)borate: [Chemical Formula A] Li 1+x [Ni a Co b Mr c M 1 d ]O 2+w In the above chemical formula A, 0≤x≤0.5, a+b+c+d = 1, 0.5≤a≤0.7, 0≤b≤0.15, c=1-abd, 0≤d≤0.1, 0≤b / a≤0.2, 1≤a / c≤3, 0≤w≤1, 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.

2. In claim 1, The above lithium secondary battery is a lithium secondary battery having an operating voltage of 4.3 V or higher.

3. In claim 1, The above additive further comprises a compound represented by the following chemical formula 1: A lithium secondary battery: [Chemical Formula 1] In the above chemical formula 1, R a1 , R b1 and R c1 are each independently hydrogen, an alkyl group having 1 to 3 carbon atoms, or -CN, and L 21 is an alkylene group having 1 to 3 carbon atoms.

4. In claim 1, A lithium secondary battery, wherein the non-aqueous electrolyte contains 0.01 to 10 wt% of the lithium bis(oxalato)borate.

5. In claim 1, A lithium secondary battery, wherein the above diethyl carbonate is contained in an amount of 7 to 15 volume% based on the total volume of the organic solvent.

6. In claim 1, A lithium secondary battery wherein the organic solvent further comprises a cyclic carbonate.

7. In claim 6, A lithium secondary battery wherein the above cyclic carbonate further comprises ethylene carbonate.

8. A lithium secondary battery according to claim 6, wherein the volume ratio of the cyclic carbonate and the linear carbonate is 5:95 to 40:

60.

9. In claim 1, A lithium secondary battery further comprising at least one additive selected from the group consisting of coumarine, fluoroethylene carbonate, vinylethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, lithium difluoro phosphate (LiDFP), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiDFOB), Tris(trimethylsilyl) Phosphate (TMSPi), and Tris(trimethylsilyl) Phosphite (TMSPi).

10. In claim 1, A lithium secondary battery, wherein the lithium salt is included in the non-aqueous electrolyte at a molar concentration of 0.5 M to 5.0 M.

11. In claim 1, A lithium secondary battery wherein the positive electrode active material is in the form of a single particle consisting of one single nodule or a quasi-single particle complex consisting of 30 or fewer nodules.

12. In claim 1, A lithium secondary battery wherein in the chemical formula A, a / (b × c) is 18 to 50.

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