Non-aqueous electrolyte and lithium secondary battery containing the same

Abstract

The present invention relates to a non-aqueous electrolyte solution containing a lithium salt, an organic solvent, and a compound represented by Chemical Formula 1, and the non-aqueous electrolyte solution can control the moisture content in a lithium secondary battery using the battery, and the moisture control can suppress the generation of by-products, improve the durability of a solid electrolyte interface film, and enhance the durability of the lithium secondary battery. JPEG2024520033000022.jpg52170In the above chemical formula 1, L 1 and L 2 are each independently selected from a single bond and an alkylene group having 1 to 5 carbon atoms, 1 is selected from hydrogen and alkyl groups having 1 to 5 carbon atoms.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0100129, filed on Jul. 29, 2021, and all the contents disclosed in the documents of the Korean patent application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery including the same.

Background Art

[0003] In recent years, with the development of the information society, personal IT devices and computer networks have been developed, and accordingly, the overall social dependence on electrical energy has increased. Therefore, there is a demand for the development of battery technologies for efficiently storing and utilizing electrical energy.

[0004] In particular, with the growing interest in solving environmental problems and realizing a sustainable recycling society, extensive research has been conducted on energy storage devices such as lithium-ion batteries and electric double layer capacitors. Among them, lithium secondary batteries have attracted attention as a battery system with the highest theoretical energy density among battery technologies.

[0005] The lithium secondary battery generally includes a positive electrode made of a transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte serving as a medium for transmitting lithium ions, and a separator. Among these, the electrolyte is known as a component having a great influence on the stability (stability, safety) of the battery, and a lot of research has been conducted thereon.

[0006] In this regard, generally, as the electrolyte of a lithium secondary battery, a non-aqueous electrolyte containing a lithium salt, an organic solvent, etc. is used, and as the organic solvent, a carbonate-based organic solvent, etc. is used. At this time, LiPF6 etc. may be used as the lithium salt, but PF6 -Since anions are very weak against heat, when the battery is exposed to high temperatures, there is a problem that Lewis acids such as PF5 are generated by thermal decomposition of lithium salts. Lewis acids such as PF5 cause decomposition of the organic solvent itself, destroy the Solid Electrolyte Interface layer (SEI layer) formed on the surface of the negative electrode active material, and cause problems such as an increase in the resistance and a decrease in the life of the lithium secondary battery.

[0007] Therefore, it is urgent to develop a non-aqueous electrolyte for a lithium secondary battery that can improve lithium ion transfer characteristics, electrochemical stability, battery durability, etc.

[0008] U.S. Patent Publication No. 2018-0316061 discloses an amide-based electrolyte battery, but no alternative to the above problems is presented.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] One problem of the present invention is to provide a non-aqueous electrolyte that can improve the high-temperature storage stability and high-temperature life characteristics of a lithium secondary battery.

[0011] Another problem of the present invention is to provide a lithium secondary battery containing the above non-aqueous electrolyte.

Means for Solving the Problems

[0012] The present invention provides a non-aqueous electrolyte containing a lithium salt, an organic solvent, and a compound represented by the following Chemical Formula 1.

[0013]

Chem.

[0014] In Chemical Formula 1, L1 and L2 are each independently selected from a single bond and an alkylene group having 1 to 5 carbon atoms, and R1 is selected from hydrogen and an alkyl group having 1 to 5 carbon atoms.

[0015] The present invention also provides a lithium secondary battery including a negative electrode, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, and the aforementioned non-aqueous electrolyte.

Advantages of the Invention

[0016] The non-aqueous electrolyte according to the present invention is characterized in that by including a lithium salt, an organic solvent, and a compound represented by a specific chemical formula, the high-temperature storage characteristics and high-temperature life characteristics of a lithium secondary battery can be improved. Specifically, the compound contained in the non-aqueous electrolyte according to the present invention can play a role of removing the Lewis acid of the lithium salt that may be generated when the lithium secondary battery is exposed to a high temperature. Therefore, it is possible to prevent the decomposition of the organic solvent and the destruction of the solid electrolyte interface film (SEI layer) of the negative electrode active material or the negative electrode caused by the Lewis acid of the lithium salt. Further, the compound represented by the specific chemical formula has a low LUMO energy level and can participate in the formation reaction of the solid electrolyte interface film of the negative electrode, so that the durability of the solid electrolyte interface film of the negative electrode can be further improved.

[0017] Therefore, the lithium secondary battery including the non-aqueous electrolyte can improve its high-temperature storage characteristics and high-temperature life characteristics.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described in more detail so that it can be easily understood. At this time, terms and words used in this specification and claims should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in a meaning and concept consistent with the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0019] Also, in this specification, terms such as "comprising", "including", or "having" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and it should be understood that they do not preclude the presence or addition possibility of one or more other features, numbers, steps, components, or combinations thereof in advance.

[0020] In this specification, the "alkyl group" may be linear or branched-chain. Also, the alkyl group may be selectively substituted. In this specification, unless otherwise defined, the "substituted" means that at least one hydrogen bonded to carbon is substituted with another element other than hydrogen, for example, it may mean being substituted with an alkyl group having 1 to 5 carbon atoms or fluorine.

[0021] In this specification, the average particle size (D 50 ) can be defined as the particle size corresponding to 50% of the volume cumulative amount in the particle size distribution curve of the particles. The average particle size (D 50 ) can be measured, for example, by the laser diffraction method. The laser diffraction method can generally measure particle sizes in the submicron region to about several millimeters, and can obtain results with high reproducibility and high resolution.

[0022] Hereinafter, the non-aqueous electrolyte of the present invention and the lithium secondary battery including the same will be described in detail.

[0023] Non-aqueous electrolyte The present invention provides a non-aqueous electrolyte. Specifically, the non-aqueous electrolyte may be a non-aqueous electrolyte for a lithium secondary battery.

[0024] Specifically, the non-aqueous electrolyte according to the present invention contains a lithium salt, an organic solvent, and a compound represented by the following Chemical Formula 1.

[0025] [Chemical formula]

[0026] In Chemical Formula 1, L1 and L2 are independently selected from a single bond and an alkylene group having 1 to 5 carbon atoms, and R1 is selected from hydrogen and an alkyl group having 1 to 5 carbon atoms.

[0027] The non-aqueous electrolyte according to the present invention is characterized in that by containing a lithium salt, an organic solvent, and a compound represented by a specific chemical formula, the high-temperature storage characteristics and high-temperature life characteristics of a lithium secondary battery can be improved. Specifically, the compound contained in the non-aqueous electrolyte according to the present invention can play a role in removing the Lewis acid of the lithium salt that may be generated when the lithium secondary battery is exposed to high temperatures. Therefore, it is possible to prevent the decomposition of the organic solvent and the destruction of the solid electrolyte interface film (SEI layer) of the negative electrode active material or the negative electrode caused by the Lewis acid of the lithium salt. In addition, the compound represented by the specific chemical formula has a low LUMO energy level and can participate in the formation reaction of the solid electrolyte interface film of the negative electrode, so the durability of the solid electrolyte interface film of the negative electrode can be further improved.

[0028] Therefore, a lithium secondary battery containing the non-aqueous electrolyte can improve its high-temperature storage characteristics and high-temperature life characteristics.

[0029] (1) Lithium salt The non-aqueous electrolyte of the present invention contains a lithium salt. The lithium salt is used as an electrolyte salt in a lithium secondary battery and serves as a medium for transmitting lithium ions.

[0030] Generally, the lithium salt may contain at least one selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3, LiC4BO8, LiTFSI, LiFSI, and LiClO4. Specifically, in consideration of the ion conduction characteristics and electrochemical stability of the electrolyte, etc., it may contain LiPF6, but is not limited thereto. On the other hand, the lithium salt may be used alone or, if necessary, two or more kinds may be mixed and used.

[0031] The lithium salt may be contained in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, preferably at a concentration of 0.5 M to 4 M. When the concentration of the lithium salt is within the above range, the concentration of lithium ions in the non-aqueous electrolyte is appropriate, the charge and discharge of the battery become smooth, and the viscosity of the non-aqueous electrolyte is appropriate, improving the wetting in the battery, so that the performance of the battery can be improved.

[0032] (2) Compound represented by Chemical Formula 1 The present invention includes a compound represented by the following Chemical Formula 1.

[0033] [Chemical formula]

[0034] In Chemical Formula 1, L1 and L2 are independently selected from a single bond and an alkylene group having 1 to 5 carbon atoms, and R1 is selected from hydrogen and an alkyl group having 1 to 5 carbon atoms.

[0035] For example, when the lithium salt is LiPF6, when the lithium salt is exposed to high temperature, PF6 -Lewis acids such as PF5 can be formed by the thermal decomposition of anions. Since such Lewis acids as PF5 may cause problems of decomposing the organic solvent in a lithium secondary battery or destroying the solid electrolyte interface film (SEI layer) formed on the negative electrode or the negative electrode active material layer, there is a risk of degrading the high-temperature durability of the lithium secondary battery.

[0036] To solve such problems, the non-aqueous electrolyte of the present invention is characterized by containing the compound represented by the above Chemical Formula 1. The compound represented by the above Chemical Formula 1 contains a functional group capable of acting as a Lewis base in its structure, so that the Lewis acid formed from the lithium salt can be effectively removed, thereby preventing the decomposition of the organic solvent and preventing damage or destruction of the solid electrolyte interface film of the negative electrode. Therefore, a lithium secondary battery using the non-aqueous electrolyte of the present invention can significantly improve the high-temperature durability such as high-temperature storage characteristics and high-temperature life characteristics.

[0037] Specifically, since the compound represented by the above Chemical Formula 1 has a five-membered ring structure, the energy level of the LUMO (lowest unoccupied molecular orbital) is low and it is easily decomposed at the negative electrode. Thereby, the compound represented by the above Chemical Formula 1 can participate in the formation reaction of the solid electrolyte interface film of the negative electrode, contributing to the improvement of the durability of the solid electrolyte interface film.

[0038] In addition, the cyano group (-CN) of the compound represented by the above Chemical Formula 1 can improve the effect of controlling the moisture in the non-aqueous electrolyte.

[0039] In the above Chemical Formula 1, L1 and L2 may each independently be selected from a single bond and an alkylene group having 1 to 5 carbon atoms, and specifically, may be a single bond.

[0040] In the above Chemical Formula 1, R1 may be selected from hydrogen and an alkyl group having 1 to 5 carbon atoms. Specifically, from the point of further reducing the possibility of generating HF when exposed to high temperatures, it may be an alkyl group having 1 to 5 carbon atoms, and more specifically, may be a methyl group.

[0041] The compound represented by the above Chemical Formula 1 may be a compound represented by the following Chemical Formula 1A.

[0042]

Chem.

[0043] The above R1 may be selected from hydrogen and an alkyl group having 1 to 5 carbon atoms. Specifically, it may be an alkyl group having 1 to 5 carbon atoms, and more specifically, it may be a methyl group.

[0044] On the other hand, the compound represented by the above Chemical Formula 1 may contain at least one selected from the group consisting of a compound represented by the following Chemical Formula 2A and a compound represented by the following Chemical Formula 2B. In this case, the moisture control effect of the cyano group can be further improved. Specifically, the compound represented by the above Chemical Formula 1 may contain a compound represented by the following Chemical Formula 2B. In this case, when exposed to high temperatures, the possibility of generating HF can be further reduced, and the high-temperature storage performance and high-temperature life performance can be further improved.

[0045]

Chem.

[0046]

Chem.

[0047] The compound represented by the above Chemical Formula 1 may be contained in the non-aqueous electrolyte at 0.01% by weight to 7% by weight, specifically 0.3% by weight to 4% by weight, and more specifically 1.5% by weight to 3.5% by weight. When in the above range, the effect of removing the Lewis acid of the above lithium salt can be fully exerted, and the high-temperature durability of the battery can be improved, which is preferable.

[0048] (3) Organic solvent The non-aqueous electrolyte according to the present invention contains an organic solvent. The 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 reaction or the like is minimized during the charge and discharge process of the secondary battery.

[0049] Specifically, the organic solvent may contain at least one selected from linear carbonates, cyclic carbonates, linear esters, cyclic esters, ethers, glymes, and nitriles. The organic solvent preferably may contain at least one selected from linear carbonates and cyclic carbonates, and more preferably may contain linear carbonates and cyclic carbonates. In particular, conventional non-aqueous electrolytes generally use cyclic carbonates as organic solvents due to their high dielectric constant, dissociation of lithium salts, etc., but the role of such cyclic carbonates can be partially replaced or replaced by the compound represented by Chemical Formula 1 described above. In particular, the compound represented by Chemical Formula 1 has high oxidation stability and excellent lithium ion transfer performance and does not generate gas by-products, so it can improve the durability and life characteristics of lithium secondary batteries. Therefore, compared with the case of using cyclic carbonates, excellent battery characteristics can be exhibited at a desirable level.

[0050] The linear carbonate may contain at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate.

[0051] The cyclic carbonate may include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, and fluoroethylene carbonate (FEC).

[0052] Specific examples of the linear ester include, but are not limited to, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0053] Specific examples of the cyclic ester include, but are not limited to, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0054] Specific examples of the ether include, but are not limited to, 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).

[0055] Specific examples of the glyme include, but are not limited to, dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0056] Specific examples of the nitrile include, but are not limited to, acetonitrile, propionitrile, butyronitrile, valeronitrile, capronitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, etc.

[0057] When the organic solvent contains the linear carbonate and the cyclic carbonate, the volume ratio of the linear carbonate to the cyclic carbonate may be 20:80 to 80:20, specifically 25:75 to 50:50.

[0058] (4) Additive The non-aqueous electrolyte may further contain an additive.

[0059] Specifically, the non-aqueous electrolyte may further contain at least one additive selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, fluoroethylene carbonate, LiPO2F2, LiODFB (lithium difluorooxalatoborate), LiBOB (lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (tris(trimethylsilyl)phosphite). Specifically, it may further contain an additive containing vinylene carbonate. When the additive is contained in the non-aqueous electrolyte, it is preferable in that it can form a stable solid electrolyte interface film (SEI layer) on the negative electrode and suppress an additional decomposition reaction of the electrolyte to improve the life characteristics.

[0060] The additive may be contained in the non-aqueous electrolyte in an amount of 0.1% by weight to 15% by weight, preferably 0.3% by weight to 5% by weight.

[0061] When the above-mentioned additive is contained in the non-aqueous electrolyte, the weight ratio of the compound represented by Chemical Formula 1 to the additive may be 0.1:1 to 11:1, specifically 3:1 to 9:1. When it is within the above range, the effect of improving the high-temperature performance by using the compound represented by Chemical Formula 1 and the additive in combination can be preferably realized.

[0062] Lithium secondary battery Furthermore, the present invention provides a lithium secondary battery including the aforementioned non-aqueous electrolyte.

[0063] Specifically, the lithium secondary battery according to the present invention includes a negative electrode, a positive electrode facing the negative electrode, a separator facing the negative electrode and the positive electrode, and the aforementioned non-aqueous electrolyte.

[0064] At this time, the lithium secondary battery of the present invention can be manufactured by a conventional method known in the art. For example, after forming an electrode assembly in which a positive electrode, a negative electrode, and a separator are sequentially laminated between the positive electrode and the negative electrode, the electrode assembly is inserted into the inside of a battery case, and the non-aqueous electrolyte according to the present invention is injected to manufacture it.

[0065] 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.

[0066] The negative electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity. Specifically, as the negative electrode current collector, copper, stainless steel, aluminum, nickel, titanium, fired carbon, those obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. may be used.

[0067] The negative electrode current collector usually has a thickness of 3 to 500 μm.

[0068] The negative electrode current collector may strengthen the binding force of the negative electrode active material by forming fine irregularities on the surface. For example, the 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 body, etc.

[0069] The negative electrode active material layer is disposed on at least one surface of the negative electrode current collector. Specifically, the negative electrode active material layer may be disposed on one or both surfaces of the negative electrode current collector.

[0070] The negative electrode active material layer may contain a negative electrode active material.

[0071] The negative electrode active material is a substance capable of reversibly intercalating / deintercalating lithium ions, and may contain at least one selected from the group consisting of carbon-based active materials, metalloid-based active materials, and lithium metal. Specifically, it may contain at least one selected from carbon-based active materials and metalloid-based active materials.

[0072] The carbon-based active material may contain at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may contain at least one selected from the group consisting of artificial graphite and natural graphite.

[0073] The average particle size (D 50 ) of the carbon-based active material may be 10 μm to 30 μm, preferably 15 μm to 25 μm, from the viewpoint of achieving structural stability during charge and discharge and reducing side reactions with the electrolyte.

[0074] Specifically, the metalloid-based active material may include at least one metalloid 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 at least one metalloid 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 and lithium; an oxide of at least one metalloid 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.

[0075] More specifically, the metalloid-based active material may include a silicon-based active material.

[0076] The silicon-based active material may contain a compound represented by SiO x (0 ≦ x < 2). Since SiO2 does not react with lithium ions, it cannot store lithium. Therefore, x is preferably within the above range, and more preferably, the silicon-based oxide may be SiO.

[0077] The average particle size (D 50 ) of the silicon-based active material may be 1 μm to 30 μm, preferably 2 μm to 15 μm, from the viewpoint of achieving structural stability during charge and discharge and reducing side reactions with the electrolyte.

[0078] The negative electrode active material may be contained in the negative electrode active material layer at 60% by weight to 99% by weight, preferably 75% by weight to 95% by weight.

[0079] The negative electrode active material layer may further contain a binder and / or a conductive material together with the negative electrode active material.

[0080] The binder is used to improve the adhesion between the negative electrode active material layer and the negative electrode current collector and thus improve the performance of the battery. For example, polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, 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 at least any one selected from the group consisting of substances in which hydrogen thereof is substituted with Li, Na, Ca, etc., or various copolymers thereof may be included.

[0081] The binder may be contained in the negative electrode active material layer in an amount of 0.5% by weight to 10% by weight, preferably 1% by weight to 5% by weight.

[0082] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0083] The conductive material may be contained in the negative electrode active material layer in an amount of 0.5% by weight to 10% by weight, preferably 1% by weight to 5% by weight.

[0084] The thickness of the negative electrode active material layer may be 10 μm to 100 μm, preferably 50 μm to 80 μm.

[0085] The negative electrode can be manufactured by coating at least one surface of a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and / or a solvent for forming the negative electrode slurry, followed by drying and rolling.

[0086] The solvent for forming the negative electrode slurry may be, for example, at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably including distilled water, from the viewpoint of facilitating the dispersion of the negative electrode active material, the binder, and / or the conductive material. The solid content of the negative electrode slurry may be 30% by weight to 80% by weight, specifically 40% by weight to 70% by weight.

[0087] The positive electrode faces the negative electrode.

[0088] The positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector.

[0089] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity. Specifically, the positive electrode current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, fired carbon, and an aluminum-cadmium alloy, preferably aluminum.

[0090] The thickness of the positive electrode current collector usually has a thickness of 3 to 500 μm.

[0091] The positive electrode current collector may strengthen the binding force of the positive electrode active material by forming fine irregularities on the surface. For example, the 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, and a non-woven fabric body.

[0092] The positive electrode active material layer is disposed on at least one side of the positive electrode current collector. Specifically, the positive electrode active material layer may be disposed on one side or both sides of the positive electrode current collector.

[0093] The positive electrode active material layer may include a positive electrode active material.

[0094] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium. Specifically, it may include a lithium transition metal composite oxide containing at least one transition metal selected from nickel, cobalt, manganese, and aluminum and lithium, preferably a lithium transition metal composite oxide containing a transition metal containing nickel, cobalt, and manganese and lithium.

[0095] For example, as the lithium transition metal composite oxide, there are lithium-manganese-based oxides (e.g., LiMnO2, LiMn2O4, etc.), lithium-cobalt-based oxides (e.g., LiCoO2, etc.), lithium-nickel-based oxides (e.g., LiNiO2, etc.), lithium-nickel-manganese-based oxides (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-z Ni z O4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt-based oxides (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), lithium-manganese-cobalt-based oxides (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt-based oxides (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or lithium-nickel-cobalt-transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.). Any one or two or more of these compounds may be included. Among them, from the viewpoint of enhancing the capacity characteristics and stability of the battery, the lithium transition metal composite oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel-manganese-cobalt oxide (e.g., Li(Ni0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), etc. may be used. Considering the significance of the improvement effect by controlling the types and content ratios of the constituent elements forming the lithium transition metal composite oxide, the lithium transition metal composite oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc. may be used, and any one or a mixture of two or more of these can be used.

[0096] More specifically, the positive electrode active material is a lithium transition metal composite oxide, and may contain 60 mol% or more of nickel based on the total number of moles of the transition metals contained in the lithium transition metal composite oxide. Specifically, the positive electrode active material is a lithium transition metal composite oxide, the transition metal contains nickel; and at least one selected from manganese, cobalt, and aluminum, and the nickel is contained in an amount of 60 mol% or more, specifically 60 mol% to 90 mol% based on the total number of moles of the transition metals. When using a lithium transition metal composite oxide using such a high content of nickel together with the aforementioned non-aqueous electrolyte, it is preferable in that it can reduce the by-products in the gas generated by structural collapse.

[0097] Further, the positive electrode active material may contain a lithium composite transition metal oxide represented by the following Chemical Formula 5.

[0098] [Chemical Formula 5] Li 1+x (Ni a Co b Mn c M d )O2

[0099] In Chemical Formula 5, M is one or more 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, and 1+x, a, b, c, and d are atomic fractions of independent elements, respectively, where 0≦x≦0.2, 0.50≦a<1, 0<b≦0.25, 0<c≦0.25, 0≦d≦0.1, and a+b+c+d=1.

[0100] Preferably, a, b, c, and d may be 0.70≦a≦0.95, 0.025≦b≦0.20, 0.025≦c≦0.20, and 0≦d≦0.05, respectively.

[0101] Also, a, b, c, and d may be 0.80≦a≦0.95, 0.025≦b≦0.15, 0.025≦c≦0.15, and 0≦d≦0.05, respectively.

[0102] Also, a, b, c, and d may be 0.85≦a≦0.90, 0.05≦b≦0.10, 0.05≦c≦0.10, and 0≦d≦0.03, respectively.

[0103] The positive electrode active material may be contained in the positive electrode active material layer at 80% to 99% by weight, preferably 92% to 98.5% by weight, in consideration of sufficient capacity exhibition of the positive electrode active material and the like.

[0104] The positive electrode active material layer may further contain a binder and / or a conductive material together with the aforementioned positive electrode active material.

[0105] The binder is a component that assists in binding an active material, a conductive material, etc. and binding to a current collector. Specifically, it may contain 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.

[0106] From the viewpoint of sufficiently ensuring the binding force between components such as the positive electrode active material, the binder may be contained in the positive electrode active material layer at 1% by weight to 20% by weight, preferably 1.2% by weight to 10% by weight.

[0107] The conductive material is used to assist and improve the conductivity of the secondary battery, and is not particularly limited as long as it does not cause a chemical change and has conductivity. Specifically, the positive electrode conductive material may contain at least one selected from the group consisting of graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably may contain carbon black from the viewpoint of improving conductivity.

[0108] From the viewpoint of sufficiently ensuring the electrical conductivity, the conductive material may be contained in the positive electrode active material layer at 1% by weight to 20% by weight, preferably 1.2% by weight to 10% by weight.

[0109] The thickness of the positive electrode active material layer may be 30 μm to 400 μm, preferably 40 μm to 110 μm.

[0110] The positive electrode can be manufactured by coating a positive electrode active material and a positive electrode slurry selectively containing a binder, a conductive material, and a solvent for forming the positive electrode slurry on the positive electrode current collector, followed by drying and rolling.

[0111] The solvent for forming the positive electrode slurry may contain an organic solvent such as NMP (N-methyl-2-pyrrolidone). The content of the solid component of the positive electrode slurry may be 40% by weight to 90% by weight, specifically 50% by weight to 80% by weight.

[0112] The separator is interposed between the positive electrode and the negative electrode.

[0113] The separator separates the negative electrode and the positive electrode and provides a migration path for lithium ions. It is not particularly limited as long as it is commonly used as a separator in a lithium secondary battery. In particular, those with low resistance to ion migration of the electrolyte and excellent electrolyte moisture retention ability are preferred. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof can be used. Also, a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, a coated separator containing a ceramic component or a polymer substance may be used to ensure heat resistance or mechanical strength, and optionally, it may be used as a single-layer or multi-layer structure.

[0114] The outer shape of the lithium secondary battery of the present invention is not particularly limited, and may be, for example, cylindrical, rectangular, pouch-shaped, coin-shaped, etc.

[0115] The lithium secondary battery according to the present invention can be used in a battery cell used as a power source for a small device, or can also be used as a unit cell in a medium- to large-sized battery module including a large number of battery cells.

[0116] The lithium secondary battery according to the present invention can be usefully used in fields of portable devices such as mobile phones, notebook computers, digital cameras, etc., and in fields of electric vehicles such as hybrid electric vehicles (HEV), electric vehicles (EV), etc.

[0117] Further, the present invention provides a battery module including the lithium secondary battery as a unit cell, and a battery pack including the battery module.

[0118] The battery module or battery pack can be used as a medium- to large-sized device power source selected from the group consisting of power tools; electric vehicles; hybrid electric vehicles; and power storage systems.

[0119] Hereinafter, the present invention will be described more specifically with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope of the description and the scope of the technical idea, and it goes without saying that such modifications and changes belong to the scope of the appended claims.

[0120] Example Example 1: Production of non-aqueous electrolyte LiPF6 as a lithium salt, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) as an organic solvent in a volume ratio of 30:70, a compound represented by the following Chemical Formula 2A, and vinylene carbonate as an additive were mixed to produce a non-aqueous electrolyte.

[0121] [Chemical formula]

[0122] The lithium salt was contained at a molar concentration of 1.0 M. The compound represented by Chemical Formula 2A was contained in the non-aqueous electrolyte at 0.5% by weight. The vinylene carbonate was contained in the non-aqueous electrolyte at 0.5% by weight.

[0123] Example 2: Production of non-aqueous electrolyte A non-aqueous electrolyte was produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 2A was contained in the non-aqueous electrolyte at 3% by weight.

[0124] Example 3: Production of non-aqueous electrolyte A non-aqueous electrolyte was produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 2A was contained in the non-aqueous electrolyte at 0.1% by weight.

[0125] Example 4: Production of non-aqueous electrolyte A non-aqueous electrolyte was produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 2A was contained in the non-aqueous electrolyte at 5% by weight.

[0126] Example 5: Production of non-aqueous electrolyte A non-aqueous electrolyte was produced in the same manner as in Example 1, except that the compound represented by the following Chemical Formula 2B was used instead of the compound represented by Chemical Formula 2A.

[0127] [Chemical formula]

[0128] Example 6: Production of non-aqueous electrolyte A non-aqueous electrolyte was produced in the same manner as in Example 5, except that the compound represented by Chemical Formula 2B was contained in the non-aqueous electrolyte at 3% by weight.

[0129] Example 7: Production of non-aqueous electrolyte An non-aqueous electrolyte solution was produced in the same manner as in Example 5, except that the compound represented by the chemical formula 2B was contained in the non-aqueous electrolyte solution at 5% by weight.

[0130] Example 8: Production of non-aqueous electrolyte solution An non-aqueous electrolyte solution was produced in the same manner as in Example 2, except that vinylene carbonate was not contained.

[0131] Comparative Example 1: Production of non-aqueous electrolyte solution An non-aqueous electrolyte solution was produced in the same manner as in Example 1, except that the compound represented by the chemical formula 2A was not contained in the non-aqueous electrolyte solution.

[0132] Comparative Example 2: Production of non-aqueous electrolyte solution An non-aqueous electrolyte solution was produced in the same manner as in Example 1, except that the compound represented by the following chemical formula 3 (cis-1,2-dicyanoethylene) was contained instead of the compound represented by the chemical formula 2A.

[0133]

Chemical formula

[0134] Comparative Example 3: Production of non-aqueous electrolyte solution An non-aqueous electrolyte solution was produced in the same manner as in Example 2, except that the compound represented by the chemical formula 3 was contained instead of the compound represented by the chemical formula 2A.

[0135] Comparative Example 4: Production of non-aqueous electrolyte solution An non-aqueous electrolyte solution was produced in the same manner as in Example 1, except that the compound represented by the following chemical formula 4 was contained instead of the compound represented by the chemical formula 2A.

[0136]

Chemical formula

[0137] Comparative Example 5: Production of non-aqueous electrolyte solution A non-aqueous electrolyte solution was produced in the same manner as in Example 2, except that the compound represented by Chemical Formula 4 was included instead of the compound represented by Chemical Formula 2A.

[0138]

Table 1

[0139] Experimental Example Experimental Example 1: Measurement of Negative Electrode Reduction Potential Using a graphite electrode as the working electrode, a lithium metal as the counter electrode, and the non-aqueous electrolyte solution of Example 1, a coin-shaped half cell of Example 1 was produced by a conventional method.

[0140] Also, coin-shaped half cells of Examples 2 to 8 and Comparative Examples 1 to 5 were produced in the same manner as in Example 1, except that the non-aqueous electrolyte solutions of Examples 2 to 8 and Comparative Examples 1 to 5 were used instead of the non-aqueous electrolyte solution of Example 1.

[0141] For the coin-shaped half cells of Examples 1 to 8 and Comparative Examples 1 to 5, cyclic voltammetry was performed between 3 V and 0 V at a scanning rate of 1 mA, and the reduction peak voltages measured therefrom are shown in Table 2 below.

[0142]

Table 2

[0143] Referring to Table 2, it can be confirmed that the non-aqueous electrolyte solutions of Examples 1 to 8 are reductively decomposed at a low potential. This means that the compound of Chemical Formula 1 is involved in the SEI film formation reaction of the negative electrode and can contribute to the improvement of the durability of the battery.

[0144] Experimental Example 2: Evaluation of High Temperature Cycle Capacity Retention Rate <Manufacture of Secondary Battery> 1. Manufacture of Negative Electrode As the negative electrode active material, artificial graphite; as the conductive material, carbon black (product name: Super C65, manufacturer: Timcal); as the binder, an acrylic binder (BM-L302, manufactured by Zeon Corporation); and as the thickener, carboxymethyl cellulose were added to a solvent for forming a negative electrode slurry at a weight ratio of 95:1.5:2.3:1.2 and added to distilled water to produce a negative electrode slurry.

[0145] On one side of a copper current collector as the negative electrode current collector, the negative electrode slurry was coated at a loading amount of 350 mg / 25 cm 2 and rolled (roll press), and dried in a vacuum oven at 130 °C for 10 hours to form a negative electrode active material layer, which was used as the negative electrode.

[0146] 2. Manufacture of the positive electrode As the positive electrode active material, Li[Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 O2, as the conductive material, carbon black (product name: Super C65, manufacturer: Timcal), and as the binder, polyvinylidene fluoride (PVdF) were added to a solvent for forming a positive electrode slurry at a weight ratio of 97.5:1.5:1.0 and added to N-methyl-2-pyrrolidone (NMP) to produce a positive electrode slurry.

[0147] On one side of an aluminum current collector as the positive electrode current collector, the positive electrode slurry was coated at a loading amount of 607 mg / 25 cm 2 and rolled (roll press), and dried in a vacuum oven at 130 °C for 10 hours to form a positive electrode active material layer, which was used as the positive electrode.

[0148] 3. Manufacture of the lithium secondary battery In a battery case, after interposing a porous separator between the positive electrode and the negative electrode manufactured above, the non-aqueous electrolyte solution manufactured in Example 1 was injected to manufacture the lithium secondary battery of Example 1.

[0149] The lithium secondary batteries of Examples 2 to 8 and Comparative Examples 1 to 5 were produced in the same manner as the production method of the lithium secondary battery of Example 1, except that the non-aqueous electrolytes of Examples 2 to 8 and Comparative Examples 1 to 5 were used instead of the non-aqueous electrolyte of Example 1.

[0150] <Evaluation of High Temperature Cycle Capacity Retention Rate> Using the lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5, the high temperature cycle capacity retention rate was evaluated.

[0151] Specifically, the lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were charged to 4.2 V under the conditions of CC / CV and 0.33C at 45 °C using an electrochemical charge and discharge device, and then discharged to 3 V under the conditions of CC and 0.33C. One cycle of charge and discharge was defined as one cycle, and 300 cycles of charge and discharge were performed, and the capacity retention rate was measured.

[0152] The capacity retention rate was calculated by the following formula, and the results are shown in Table 3 below.

[0153] Capacity retention rate (%) = (Discharge capacity after 300 cycles / Discharge capacity after 1 cycle) × 100

[0154] Experimental Example 3: Evaluation of High Temperature Cycle Resistance Increase Rate The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared in the same manner as the method described in Experimental Example 2.

[0155] The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were charged to 4.2 V under the conditions of CC / CV and 0.33C at 45 °C, and then discharged to 3 V under the conditions of CC and 0.33C. One cycle of charge and discharge was defined as one cycle, and 300 cycles of charge and discharge were performed.

[0156] After one cycle of charge and discharge, the discharge capacity after 1 cycle was measured using an electrochemical charge and discharge device. After adjusting the SOC to 50%, a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated from the difference between the voltage before the pulse application and the voltage after the application.

[0157] After 300 charge-discharge cycles, the resistance after 300 cycles was calculated by the same method as above, the resistance increase rate was calculated using the following formula, and the results are shown in Table 3 below.

[0158] Resistance increase rate (%) = (Resistance after 300 cycles - Initial resistance) / Initial resistance × 100

[0159] Experimental Example 4: Evaluation of high-temperature cycle volume increase rate Lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared by the same method as described in Experimental Example 2.

[0160] The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were subjected to charge and discharge for 300 cycles by the same method as in Experimental Example 2. At this time, the volume of the lithium secondary battery before charge and discharge (initial volume) and the volume of the lithium secondary battery after 300 cycles were measured, the volume increase rate was calculated by the following formula, and the results are shown in Table 3 below.

[0161] Volume increase rate (%) = (Volume of lithium secondary battery after 300 cycles - Initial volume) / Initial volume × 100

[0162]

Table 3

[0163] Referring to Table 3, it can be confirmed that the lithium secondary batteries of Examples 1 to 8 using the non-aqueous electrolyte containing the compound represented by Chemical Formula 1 are superior in high-temperature cycle life performance, have a lower resistance increase rate due to cycling, and less volume increase due to cycling compared to the lithium secondary batteries of Comparative Examples 1 to 5.

[0164] Experimental Example 5: Evaluation of capacity retention rate after high-temperature storage Lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared by the same method as described in Experimental Example 2.

[0165] The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were charged at room temperature under constant current / constant voltage (CC / CV) conditions of 0.33C / 4.25V up to 4.25V / 55mA and discharged at 0.33C down to 2.5V to perform initial charge and discharge. Thereafter, they were charged at room temperature under constant current / constant voltage (CC / CV) of 0.33C / 4.25V up to 4.25V / 55mA and then stored at 60°C for 12 weeks. After storage, the secondary batteries were charged at room temperature under constant current / constant voltage (CC / CV) conditions of 0.33C / 4.25V up to 4.25V / 55mA and discharged at 0.33C down to 2.5V, and the capacity during discharge was measured.

[0166] The capacity retention rate was evaluated according to the following formula, and the results are shown in Table 4 below.

[0167] Capacity retention rate (%) = (Discharge capacity after 12-week storage / Initial discharge capacity) × 100

[0168] Experimental Example 6: Evaluation of resistance increase rate after high-temperature storage Lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared by the same method as described in Experimental Example 2.

[0169] The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were initially charged and discharged by the same method as in Experimental Example 5. After confirming the capacity at room temperature, they were charged at SOC50 based on the discharge capacity and discharged at a 3C current for 10 seconds. The resistance was measured from the voltage drop difference at this time as the initial resistance, and after storage at 60°C for 12 weeks, the resistance was measured by the same method as the final resistance. The resistance increase rate was calculated according to the following formula. The results are shown in Table 4 below.

[0170] Resistance increase rate (%) = (Final resistance - Initial resistance) / (Initial resistance) × 100

[0171] Experimental Example 7: Evaluation of volume increase rate after high-temperature storage Lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were prepared by the same method as described in Experimental Example 2.

[0172] The lithium secondary batteries of Examples 1 to 8 and Comparative Examples 1 to 5 were initially charged and discharged by the same method as in Experimental Example 5. Each battery was set to SOC50 based on the discharge capacity, and the volume was measured, which was defined as the initial volume. The volume measured after high-temperature storage at 60°C for 12 weeks at SOC100% was defined as the final volume, and the volume increase rate of the battery was calculated by the following formula. The results are shown in Table 4 below.

[0173] Volume increase rate (%) = ((Final volume - Initial volume) / Initial volume) × 100

[0174]

Table 4

[0175] Referring to Table 4, it can be confirmed that the lithium secondary batteries of Examples 1 to 8 using the non-aqueous electrolyte containing the compound represented by Chemical Formula 1 are superior in high-temperature storage life performance, have a low resistance increase rate, and little volume increase compared to the lithium secondary batteries of Comparative Examples 1 to 5.

[0176] Experimental Example 8: Measurement of water content in electrolyte A sample solution of Example 1A containing 0.5% by weight of the compound represented by Chemical Formula 2A was prepared in a solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a volume ratio of 3:7.

[0177] For the sample solution of Example 1A one hour after the addition of the compound represented by Chemical Formula 2A, the water content in the electrolyte was measured using a Metrohm 756 Karl Fischer Coulometer instrument. The measurement was performed three times, and the average value of these electrolyte water contents was taken as the electrolyte water content of the Example 1A sample solution, which is shown in Table 5 below.

[0178] Except for using the sample solutions of Examples 2A to 7A and Comparative Examples 1A to 3A described in Table 5 below, the electrolyte water content was measured by the same method as above, and the results are shown in Table 5 below.

[0179]

Table 5

[0180] Referring to Table 5, it was confirmed that the sample solutions of Examples 1A to 7A containing the compound represented by Chemical Formula 1 had a very small amount of moisture in the electrolyte compared to the sample solutions of Comparative Examples 1A to 3A which did not. This is due to the remarkably excellent ability of the compound represented by Chemical Formula 1 to remove Lewis acid. As a result, when a non-aqueous electrolyte containing the compound represented by Chemical Formula 1 is applied to a lithium secondary battery, the high-temperature durability such as the high-temperature storage characteristics and high-temperature life characteristics of the lithium secondary battery can be remarkably improved.

Claims

1. A lithium salt, an organic solvent, a compound represented by the following Chemical Formula 1, and includes: The lithium salt contains at least one selected from the group consisting of LiPF6, LiBF4, LiSbF6, and LiAsF6, a non-aqueous electrolyte: 【Chemical 1】 (In the above chemical formula 1, L １ and L ２ are each independently selected from a single bond and an alkylene group having 1 to 5 carbon atoms, The aforementioned R １ is selected from hydrogen and alkyl groups having 1 to 5 carbon atoms.)

2. The non-aqueous electrolyte according to Claim 1, wherein the compound represented by Chemical Formula 1 is a compound represented by the following Chemical Formula 1A: [Chemical 2] (In the above chemical formula 1A, the R １ is selected from hydrogen and alkyl groups having 1 to 5 carbon atoms.)

3. The non-aqueous electrolyte according to Claim 1, wherein the compound represented by Chemical Formula 1 contains at least one selected from the group consisting of a compound represented by the following Chemical Formula 2A and a compound represented by the following Chemical Formula 2B. 【Chemical Formula 3】 【Chemical Formula 4】

4. The non-aqueous electrolyte according to Claim 1, wherein the compound represented by Chemical Formula 1 contains a compound represented by the following Chemical Formula 2B. 【Chemical Formula 5】

5. The non-aqueous electrolyte according to Claim 1, wherein the compound represented by Chemical Formula 1 is contained in the non-aqueous electrolyte in an amount of 0.01% by weight to 7% by weight.

6. The non-aqueous electrolyte according to Claim 1, wherein the compound represented by Chemical Formula 1 is contained in the non-aqueous electrolyte in an amount of 1.5% by weight to 3.5% by weight.

7. The lithium salt is LiPF ６ The non-aqueous electrolyte according to claim 1, which contains ６ .

8. The non-aqueous electrolyte according to Claim 1, wherein the lithium salt is contained in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M.

9. The non-aqueous electrolyte according to Claim 1, wherein the organic solvent contains at least one selected from linear carbonates and cyclic carbonates.

10. The non-aqueous electrolyte is at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, fluoroethylene carbonate, LiPO ２ F ２ , LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSSa (3-trimethoxysilyl-propyl-N-aniline), and TMSSi (Tris(trimethylsilyl)Phosphite), and further includes at least one additive selected from the group consisting of the non-aqueous electrolyte according to claim 1.

11. The non-aqueous electrolyte according to Claim 10, wherein the additive is vinylene carbonate.

12. The non-aqueous electrolyte according to Claim 10, wherein the additive is contained in the non-aqueous electrolyte in an amount of 0.1% by weight to 15% by weight.

13. A negative electrode, a positive electrode facing the negative electrode, a separator interposed between the negative electrode and the positive electrode, A lithium secondary battery including the non-aqueous electrolyte according to any one of Claims 1 to 12.

14. The positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, The positive electrode active material layer contains a positive electrode active material, The lithium secondary battery according to Claim 13, wherein the positive electrode active material contains a lithium composite transition metal oxide represented by the following Chemical Formula 5. [Chemical Formula 5] Li １＋ｘ (Ni ａ Co ｂ Mn ｃ M ｄ )O ２ (In the above Chemical Formula 5, M is one or more 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, 1 + x, a, b, c, and d are the atomic fractions of independent elements, respectively, and 0 ≤ x ≤ 0.2, 0.50 ≤ a < 1, 0 < b ≤ 0.25, 0 < c ≤ 0.25, 0 ≤ d ≤ 0.1, and a + b + c + d = 1.)

15. The lithium secondary battery according to claim 14, wherein a, b, c, and d in the chemical formula 5 are 0.80 ≤ a ≤ 0.95, 0.025 ≤ b ≤ 0.15, 0.025 ≤ c ≤ 0.15, and 0 ≤ d ≤ 0.05, respectively.

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