Nonaqueous electrolyte for lithium secondary battery and lithium secondary battery containing same

Abstract

The present invention provides a non-aqueous electrolyte for a lithium secondary battery and a lithium secondary battery containing the same. Specifically, the non-aqueous electrolyte for a lithium secondary battery contains a lithium salt, an organic solvent, and a compound represented by Chemical Formula 1, and thus can form a strong SEI film and improve battery performance.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0135188 dated October 12, 2021 and Korean Patent Application No. 10-2022-0127418 dated October 5, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated as part of this specification.

[0002] The present invention relates to a nonaqueous electrolyte for lithium secondary batteries containing an additive capable of forming a strong SEI film, and a lithium secondary battery containing the same, which can suppress an increase in initial resistance and improve output characteristics. [Background technology]

[0003] The development of the information society has led to the development of personal IT devices and computer networks, which has resulted in society as a whole becoming more dependent on electrical energy. This has created a demand for the development of technologies to efficiently store and utilize electrical energy.

[0004] Of the technologies currently being developed, secondary batteries are the most suitable for a variety of applications, and among these secondary batteries, interest is growing in lithium-ion batteries, which not only can be miniaturized to a size suitable for use in personal IT devices, but also have the highest energy density.

[0005] A lithium-ion battery is composed of a positive electrode made of a transition metal oxide containing lithium, a negative electrode made of a carbon-based material such as graphite that can store lithium, an electrolyte that acts as a medium for transmitting lithium ions, and a separator. In order to improve the electrochemical properties of the battery, it is important to select the appropriate components.

[0006] On the other hand, when a lithium secondary battery is operated under high temperature conditions, lithium salts such as LiPF6 contained in the electrolyte are converted to PF6 -The anions are thermally decomposed to form Lewis acids such as PF5, which react with moisture to generate HF. Such substances such as PF5 or HF may not only destroy the coating formed on the surface of the electrode, but may also cause a decomposition reaction of the organic solvent. As a result, a side reaction between the exposed positive electrode surface and the electrolyte induces the elution of transition metal ions from the positive electrode. In this way, the transition metal ions of the positive electrode are eluted, making the lattice structure of the positive electrode unstable, which generates active oxygen at the positive electrode, further promoting the decomposition of the electrolyte solvent and accelerating the generation of gas. Furthermore, the eluted transition metal ions move to the negative electrode through the electrolyte and are then electrodeposited on the surface of the negative electrode, causing the destruction of the SEI (solid electrolyte interphase) film and the consumption of additional lithium ions due to the regeneration reaction, which causes an increase in resistance and a decrease in capacity.

[0007] Therefore, various studies are being conducted to develop secondary batteries that can maintain the passivation properties of the SEI film and achieve excellent performance even under high temperature conditions. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve the above problems, and has an object to provide a nonaqueous electrolyte solution for a lithium secondary battery containing an additive capable of imparting an SEI strengthening effect, and a lithium secondary battery containing the same, which has improved output characteristics and suppresses an increase in battery resistance. [Means for solving the problem]

[0009] According to one embodiment, the present invention provides a non-aqueous electrolyte for a lithium secondary battery, comprising a lithium salt, a non-aqueous organic solvent, and a compound represented by the following Chemical Formula 1:

[0010] [ka]

[0011] In the above Chemical Formula 1, R1 and R2 each independently represent an alkylene group having 1 to 10 carbon atoms; R3 is one or more fluorines. in It is a substituted alkyl group having 1 to 20 carbon atoms.

[0012] According to another embodiment, the present invention provides a lithium secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the negative electrode and the positive electrode, and the nonaqueous electrolyte for the lithium secondary battery of the present invention. Effect of the Invention

[0013] The compound represented by Chemical Formula 1 contained in the non-aqueous electrolyte for a lithium secondary battery of the present invention has a propargyl group (-C≡C-) and one or more fluorine atoms in its structure. in Because it contains a substituted fluorocarbon functional group, it is reduced prior to the organic solvent, and a low-resistance SEI coating containing a fluorocarbon component can be formed on the surface of the electrode, thereby suppressing additional reductive decomposition reactions of the nonaqueous electrolyte.

[0014] Therefore, when the nonaqueous electrolyte for a lithium secondary battery is contained, a lithium secondary battery can be realized which prevents the self-discharge reaction of the negative electrode, suppresses an increase in initial resistance, and has improved room temperature and low temperature output characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] First, before describing the present invention, the terms and words used in this specification and claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0016] On the other hand, the terms used in this specification are merely used to describe exemplary embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless otherwise clearly indicated in the context.

[0017] As used herein, terms such as "comprise," "comprise," or "have" are intended to specify the presence of embodied features, numerals, steps, components, or combinations thereof, but should be understood as not precluding the presence or additional possibility of one or more other features, numerals, steps, components, or combinations thereof.

[0018] In this specification, "%" means % by weight unless expressly indicated otherwise.

[0019] Prior to describing the present invention, in the description of "carbon number a to b" in the specification, "a" and "b" refer to the number of carbon atoms contained in a specific functional group. That is, the functional group may contain "a" to "b" carbon atoms.

[0020] In addition, in this specification, unless otherwise defined, "substituted" means that at least one hydrogen bonded to a carbon is replaced with an element other than hydrogen, for example, with an alkyl group having 1 to 5 carbon atoms or a fluorine element.

[0021] The present invention will now be described in more detail.

[0022] In general, in lithium secondary batteries, a coating having passivation properties is formed on the surfaces of the positive and negative electrodes as the non-aqueous electrolyte is decomposed during initial charge and discharge, thereby ensuring high-temperature storage properties. However, the coating is deteriorated by Lewis acids such as HF and PF5, which are generated by thermal decomposition of lithium salts (such as LiPF6) that are widely used in lithium ion batteries. That is, when a transition metal element is dissolved from the positive electrode due to the attack of the Lewis acid, the surface structure changes, the surface resistance of the electrode increases, and the theoretical capacity decreases as the metal element, which is the redox center, disappears, so that the expressed capacity may decrease. In addition, the dissolved transition metal ions are electrodeposited on the negative electrode, which reacts in a strong reduction potential zone, and not only electrons are consumed, but the coating is destroyed during electrodeposition. As a result, the surface of the negative electrode is exposed, which causes an additional non-aqueous electrolyte decomposition reaction, which increases the resistance and irreversible capacity of the negative electrode, and the cell output characteristics are continuously reduced.

[0023] Therefore, in the present invention, in order to form a stable coating, a propargyl group (-C≡C-) and one or more fluorine atoms are contained in the molecular structure. in The present invention provides a nonaqueous electrolyte for lithium secondary batteries that contains a compound having a substituted fluorocarbon functional group as an additive, thereby enabling the formation of a low-resistance SEI coating, and a lithium secondary battery containing the same.

[0024] Nonaqueous electrolyte for lithium secondary batteries The present invention provides a non-aqueous electrolyte for a lithium secondary battery, comprising a lithium salt, a non-aqueous organic solvent, and a compound represented by the following Chemical Formula 1:

[0025] [ka]

[0026] In the above Chemical Formula 1, R1 and R2 each independently represent an alkylene group having 1 to 10 carbon atoms; R3 is one or more fluorines. in It is a substituted alkyl group having 1 to 20 carbon atoms.

[0027] (1) Lithium salt First, the lithium salt will be described as follows.

[0028] In the non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention, the lithium salt may be any of those commonly used in electrolytes for lithium secondary batteries, without any limitation. For example, Li + and as an anion, 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 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , and (CF3CF2SO2)2N- Specifically, the lithium salt may be LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB (C2O4) 2), LiCF3SO3, LiTFSI (LiN (SO2CF3) 2), LiFSI (LiN (SO2F) 2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN (SO2CF2CF3) 2). Specifically, the lithium salt may include a single substance or a mixture of two or more substances 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), and more specifically, may include LiPF6.

[0029] The lithium salt may be appropriately changed within a range that is normally usable, but in order to obtain an optimal effect of forming a corrosion prevention coating on the electrode surface, it may be contained in the electrolyte at a concentration of 0.8 M to 3.0 M, specifically, at a concentration of 1.0 M to 3.0 M.

[0030] When the concentration of the lithium salt satisfies the above range, the viscosity of the nonaqueous electrolyte can be controlled to achieve optimal impregnation, and the mobility of lithium ions can be improved, thereby improving the capacity characteristics and cycle characteristics of the lithium secondary battery.

[0031] (2) Non-aqueous organic solvent The non-aqueous organic solvent is described as follows.

[0032] The non-aqueous organic solvent may include at least one of a cyclic carbonate compound, a linear carbonate compound, and a linear ester compound.

[0033] The cyclic carbonate compound is a high-viscosity organic solvent that has a high dielectric constant and easily dissociates a lithium salt in the non-aqueous electrolyte solution, and specific examples thereof may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, may include at least one of ethylene carbonate and propylene carbonate (PC).

[0034] The linear carbonate compound is an organic solvent having low viscosity and low dielectric constant, and a representative example thereof is at least one organic solvent 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, and specifically may include ethyl methyl carbonate (EMC).

[0035] Specific examples of the linear ester compound 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, and may typically include at least one of ethyl propionate and propyl propionate.

[0036] In the present invention, in order to prepare an electrolyte solution having high ionic conductivity, a mixed solvent of a cyclic carbonate compound, a linear carbonate compound, and a linear ester compound may be used as the non-aqueous organic solvent. Meanwhile, the content of the cyclic carbonate compound in the total content of the non-aqueous organic solvent of the present invention may be 50% by volume or less, specifically 40% by volume or less, preferably 30% by volume or less.

[0037] The non-aqueous organic solvent may further contain at least one of a cyclic ester compound, an ether compound, an amide compound, and a nitrile compound.

[0038] The cyclic ester compound includes at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0039] As the ether compound, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, and ethyl propyl ether, or a mixture of two or more of these can be used.

[0040] In addition, the nitrile compound may be at least one selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0041] Meanwhile, in the non-aqueous electrolyte for a lithium secondary battery of the present invention, the remainder, excluding the lithium salt and the additives, is a non-aqueous organic solvent, unless otherwise specified.

[0042] (3) Electrolyte Additives The nonaqueous electrolyte for a lithium secondary battery of the present invention may contain a compound represented by the following chemical formula 1 as an electrolyte additive.

[0043] [ka]

[0044] In the above Chemical Formula 1, R1 and R2 each independently represent an alkylene group having 1 to 10 carbon atoms; R3 is one or more fluorines. in It is a substituted alkyl group having 1 to 20 carbon atoms.

[0045] Specifically, the compound represented by Chemical Formula 1 contains a propargyl functional group in its structure, and thus can be easily reductively decomposed on the surface of the negative electrode to form an SEI film having low resistance and high passivity. This not only improves the durability of the negative electrode itself, but also prevents electrodeposition of transition metals on the surface of the negative electrode, thereby preventing the self-discharge reaction of graphite-based and silicon-based negative electrodes caused by additional reductive decomposition of the electrolyte due to the instability of the SEI film.

[0046] In addition, the compound represented by Chemical Formula 1 has one or more fluorine atoms at the end of the structure. in By containing a substituted fluorocarbon functional group, a coating having oxidation resistance is formed on the surface of the positive electrode, thereby suppressing the elution of metallic impurities from the positive electrode and inhibiting the eluted metal ions from being electrodeposited and precipitated on the negative electrode, thereby preventing an internal short circuit.

[0047] In this way, the nonaqueous electrolyte of the present invention contains as an additive the compound represented by Chemical Formula 1, which contains a fluorocarbon functional group substituted with one or more fluorine elements and a propargyl group, which has excellent flame retardancy and non-flammability. This forms a strong SEI coating having low resistance, and not only suppresses the additional reductive decomposition reaction of the electrolyte, but also prevents the self-discharge reaction of the negative electrode. This makes it possible to manufacture a lithium secondary battery that suppresses an increase in initial resistance and has improved room temperature and low temperature output characteristics.

[0048] On the other hand, in the compound represented by the above Chemical Formula 1, R1 and R2 are each independently an alkylene group having 1 to 5 carbon atoms, and R3 is one or more fluorine atoms. in It may be a substituted alkyl group having 3 to 20 carbon atoms.

[0049] In the compound represented by the above chemical formula 1, R1 and R2 are each independently an alkylene group having 1 to 3 carbon atoms, and R3 is one or more fluorine atoms. in It may be a substituted alkyl group having 3 to 15 carbon atoms.

[0050] Specifically, in the compound represented by the formula 1, R3 is one or more fluorine atoms. in It may be a substituted alkyl group having 3 to 10 carbon atoms.

[0051] Preferably, the compound represented by Chemical Formula 1 may be at least one of the compounds represented by Chemical Formulas 1a to 1c below.

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] Meanwhile, the compound represented by Chemical Formula 1 may be included in an amount of 0.01 wt % to 10.0 wt % based on the total weight of the non-aqueous electrolyte for a lithium secondary battery.

[0056] When the content of the compound represented by Chemical Formula 1 is within the above range, defects such as side reactions, capacity reduction, and resistance increase due to additives can be minimized, and a low-resistance SEI coating can be formed on the surface of the negative electrode, improving the lithium migration effect in the coating, suppressing additional reduction decomposition reactions of the electrolyte, and preventing self-discharge reactions of the negative electrode.

[0057] Specifically, when the content of the compound represented by Chemical Formula 1 is 0.01 wt % or more, a stable coating is formed during the operation of the battery, and a low-resistance SEI coating is formed on the surface of the negative electrode, thereby improving the battery output performance. Also, when the content of the compound represented by Chemical Formula 1 is 10.0 wt % or less, the viscosity of the non-aqueous electrolyte can be controlled to achieve optimal impregnation, and an increase in battery resistance due to decomposition of additives can be effectively suppressed, and the ion conductivity in the battery can be further increased, thereby preventing a decrease in output characteristics.

[0058] Specifically, the compound represented by Chemical Formula 1 may be contained in the non-aqueous electrolyte solution in an amount of 0.1% by weight to 6.0% by weight, specifically 0.5% by weight to 5% by weight, and preferably 0.5% by weight to 3% by weight.

[0059] (4) Other additives Meanwhile, the nonaqueous electrolyte of the present invention may further contain other additives in addition to the compound represented by Formula 1, if necessary, in order to prevent the nonaqueous electrolyte from being decomposed in a high-output environment, which may cause the collapse of the negative electrode, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and the effect of suppressing battery expansion at high temperatures.

[0060] Examples of such other additives include at least one selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate or phosphite compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0061] The cyclic carbonate compound may be, for example, vinylene carbonate (VC) or vinyl ethylene carbonate (VEC).

[0062] The halogen-substituted carbonate compound may be, for example, fluoroethylene carbonate (FEC).

[0063] The sultone compound may be, for example, at least one compound selected from the group consisting of 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone.

[0064] The sulfate compound may be, for example, ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0065] The phosphate or phosphite compound may be, for example, one or more compounds selected from the group consisting of lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, tris(2,2,2-trifluoroethyl)phosphate, and tris(trifluoroethyl)phosphite.

[0066] The borate-based compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalatoborate (LiB(C2O4)2, LiBOB).

[0067] The nitrile compound may be, for example, at least one compound selected from the group consisting of succinonitrile (SN), adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0068] The benzene-based compound may be, for example, fluorobenzene, the amine-based compound may be, for example, triethanolamine or ethylenediamine, and the silane-based compound may be, for example, tetravinylsilane.

[0069] The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and examples of the lithium salt-based compound include lithium difluorophosphate (LiPO2F2) and LiBF4.

[0070] Among these additives, when vinylene carbonate, vinyl ethylene carbonate, or succinonitrile is included, a stronger SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery.In addition, when LiBF4 is included, the generation of gas that may be generated by decomposition of the electrolyte during high-temperature storage can be suppressed, and the high-temperature stability of the secondary battery can be improved.

[0071] The other additives may be used in combination of two or more compounds, and the total content of the compound represented by Formula 1 and the other additives may be 50% by weight or less, specifically 0.05 to 20% by weight, specifically 0.05 to 10% by weight, based on the total weight of the non-aqueous electrolyte. When the total content of the additives satisfies the above range, the low-temperature output characteristics of the battery can be improved, the high-temperature storage characteristics and the high-temperature life characteristics can be more effectively improved, and the occurrence of side reactions in the battery due to the additives remaining after the reaction can be prevented.

[0072] Lithium secondary battery In addition, another embodiment of the present invention provides a lithium secondary battery including the non-aqueous electrolyte for a lithium secondary battery of the present invention.

[0073] Specifically, the lithium secondary battery may include a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the negative electrode and the positive electrode, and the non-aqueous electrolyte for a lithium secondary battery of the present invention described above.

[0074] On the other hand, the lithium secondary battery of the present invention can be manufactured by forming an electrode assembly in which a positive electrode, a separator, and a negative electrode are laminated in this order, housing the electrode assembly in a battery case, and then injecting the non-aqueous electrolyte of the present invention described above.

[0075] The method for manufacturing such a lithium secondary battery of the present invention can be manufactured and applied by a conventional method known in the art, and specifically, it is as described below.

[0076] (1) Positive electrode The positive electrode according to the present invention includes a positive electrode active material layer containing a positive electrode active material, and, if necessary, the positive electrode active material layer may further include a conductive material and / or a binder.

[0077] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may include a lithium transition metal oxide containing one or more metals selected from cobalt, manganese, nickel, or aluminum and lithium. Specifically, lithium-manganese-based oxides, lithium iron phosphate, and lithium-nickel-manganese-cobalt-based oxides (for example, Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) may be included.

[0078] Specifically, the lithium-manganese oxide may be LiMnO2 or LiMn2O4, and the lithium iron phosphate may be LiFePO4.

[0079] The lithium-nickel-manganese-cobalt-based oxide is Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, 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, and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, and among them, it is preferable to include a lithium transition metal oxide in which the nickel content in the transition metal is 60 atm% or more. In other words, the higher the nickel content in the transition metal, the higher the capacity that can be realized, so using one in which the nickel content is 60 atm% or more is advantageous in realizing high capacity. As such a lithium composite metal oxide, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 ) O2.

[0080] On the other hand, the positive electrode active material of the present invention may be, in addition to the lithium transition metal oxide, a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2(0 <Y<1)、LiMn 2-Z NiZ O4 (0 < Z < 2), lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (0 < Y1 < 1), lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (0 < Z1 < 2), lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p1 Co q1 Mn r2 )O4 (0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are atomic fractions of independent elements, respectively, where 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc. One or more of these compounds may be further included.

[0081] The positive electrode active material may be contained in an amount of 90% to 99% by weight, specifically 93% to 98% by weight, based on the total weight of the solid content in the positive electrode active material layer.

[0082] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and examples of the conductive material that can be used include carbon powders such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; graphite powders such as natural graphite, artificial graphite, and graphite with highly developed crystal structures; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0083] The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the solid content in the positive electrode active material layer.

[0084] The binder is a component that plays a role in improving the adhesion between the positive electrode active material particles and the adhesive strength between the positive electrode active material and the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the solid content in the positive electrode active material layer. Examples of such binders include fluororesin-based binders including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders including styrene butadiene rubber (SBR), acrylonitrile butadiene rubber, and styrene-isoprene rubber; cellulose-based binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol-based binders including polyvinyl alcohol; polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester-based binders; and silane-based binders.

[0085] The positive electrode of the present invention may be manufactured by a method known in the art. For example, the positive electrode may be manufactured by a method of forming a positive electrode active material layer by coating a positive electrode slurry prepared by dissolving or dispersing a positive electrode active material, a binder, and / or a conductive material in a solvent on a positive electrode current collector, drying and rolling the resulting layer, or by casting the positive electrode active material layer on a separate support, peeling off the support, and laminating the resulting film on a positive electrode current collector.

[0086] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel whose surface has been surface-treated with carbon, nickel, titanium, silver, or the like may be used.

[0087] The solvent may contain an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a suitable viscosity when the positive electrode active material, and optionally a binder and a conductive material, etc. are contained. For example, the active material slurry containing the positive electrode active material, and optionally a binder and a conductive material may be contained so that the solid content concentration in the active material slurry is 10% by weight to 70% by weight, preferably 20% by weight to 60% by weight.

[0088] (2) Negative electrode Next, the negative electrode will be described.

[0089] The negative electrode according to the present invention includes a negative electrode active material layer containing a negative electrode active material, and the negative electrode active material layer may further include a conductive material and / or a binder, as necessary.

[0090] The negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal, an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0091] The carbon material capable of reversibly intercalating / deintercalating lithium ions can be used without particular limitation as long as it is a carbon-based negative electrode active material generally used in lithium-ion secondary batteries. Representative examples thereof include crystalline carbon, amorphous carbon, or both of these may be used. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0092] As the metal or an alloy of these metals and lithium, a 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, and Sn or an alloy of these metals and lithium can be used.

[0093] Examples of the metal composite oxide include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0 ≦ x ≦ 1), Li x WO2 (0 ≦ x ≦ 1), and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) can be used.

[0094] Examples of the substance capable of doping and undoping lithium include Si, SiO x (0 < x < 2), Si-Y alloy (where Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (where Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Sn), etc. Further, at least one of these may be mixed with SiO2 and used. The element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0095] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, etc.

[0096] The negative electrode active material may be contained in an amount of 80% to 99% by weight based on the total weight of the solid content in the negative electrode active material layer.

[0097] The conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 1 to 20% by weight based on the total weight of the solid content in the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and may be, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives.

[0098] The binder is a component that assists the bonding between the conductive material, the active material, and the current collector, and is usually added in an amount of 1 to 30% by weight based on the total weight of the solid content in the negative electrode active material layer. Examples of such binders include fluororesin-based binders including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose-based binders including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol-based binders including polyvinyl alcohol; polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester-based binders; and silane-based binders.

[0099] The negative electrode may be manufactured by a method known in the art, for example, by coating a negative electrode active material slurry prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, rolling and drying the resulting negative electrode active material layer, or by casting the negative electrode active material layer on a separate support, peeling off the support, and laminating the resulting film on the negative electrode current collector.

[0100] The negative electrode current collector generally has a thickness of 3 to 500 μm. Such a 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, and for example, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. may be used. In addition, as with the positive electrode current collector, the binding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0101] The solvent may include water or an organic solvent such as NMP or alcohol, and may be used in an amount that provides a suitable viscosity when the negative electrode active material and, optionally, a binder and a conductive material are contained therein. For example, the solvent may be contained so that the concentration of solids in the active material slurry containing the negative electrode active material and, optionally, a binder and a conductive material, is 50% by weight to 75% by weight, preferably 50% by weight to 65% by weight.

[0102] (3) Separator The lithium secondary battery according to the present invention includes a separator between the positive electrode and the negative electrode.

[0103] The separator separates the negative electrode and the positive electrode and provides a path for lithium ion migration. Any separator that is typically used as a separator in a lithium secondary battery can be used without any particular limitation. In particular, a separator that has low resistance to the migration of electrolyte ions and has excellent electrolyte moisture-absorbing ability is preferred.

[0104] Specifically, the separator may be a porous polymer film, 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, or an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof. Also, a normal porous nonwoven fabric, for example, a nonwoven fabric made of a high melting point glass fiber, a polyethylene terephthalate fiber, or the like, may be used. Also, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymeric substance may be used, and may be selectively used as a single layer or a multilayer structure.

[0105] The lithium secondary battery according to the present invention can be effectively used in portable devices such as mobile phones, notebook computers, and digital cameras, and in electric vehicles such as hybrid electric vehicles (HEVs).

[0106] According to another embodiment of the present invention, there is provided a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same.

[0107] The battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, including power tools; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); and power storage systems.

[0108] The external shape of the lithium secondary battery of the present invention is not particularly limited, and may be a cylindrical shape using a can, a square shape, a pouch shape, a coin shape, or the like.

[0109] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for small devices, but also suitably as a unit battery in a medium- to large-sized battery module containing a large number of battery cells.

[0110] The present invention will now be described in more detail with reference to specific examples.

[0111] In this regard, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those having ordinary skill in the art.

[0112] The present invention will now be described in more detail with reference to specific examples.

[0113] Working Example Example 1. (Production of non-aqueous electrolyte) LiPF6 was dissolved in a non-aqueous organic solvent in a volume ratio of 20:10:20:50 containing ethylene carbonate (EC), propylene carbonate (PC), ethyl propionate (EP), and propyl propionate (PP), and the solution was dissolved to a concentration of 1.0M. Then, 0.1% by weight of the compound represented by formula 1a and other additives such as vinyl ethylene carbonate (hereinafter referred to as "VEC"), 0.5% by weight of 1,3-propane sultone (hereinafter referred to as "PS"), 5.0% by weight of fluoroethylene carbonate (hereinafter referred to as "FEC"), 1.0% by weight of succinonitrile (hereinafter referred to as "SN"), and 0.5% by weight of lithium oxalyl difluoroborate (hereinafter referred to as "LiODFB") were added to the solution to prepare a non-aqueous electrolyte (see Table 1 below).

[0114] (Secondary battery manufacturing) A positive electrode slurry (solid content 50 wt%) was prepared by adding a positive electrode active material (LiCoO2), carbon black as a conductive material, and polyvinylidene fluoride as a binder in a weight ratio of 97.5:1:1.5 to a solvent N-methyl-2-pyrrolidone (NMP). The positive electrode slurry was applied to a positive electrode current collector (aluminum thin film) with a thickness of 15 μm, dried, and then roll pressed to prepare a positive electrode.

[0115] Anode active material (graphite), binder (SBR-CMC), and conductive material (carbon black) were mixed in a weight ratio of 95:3.5:1.5 to water as a solvent to prepare anode slurry (solid content: 60 wt%). The anode slurry was applied to a copper (Cu) thin film as anode current collector with a thickness of 6 μm, dried, and then roll pressed to prepare anode.

[0116] The positive electrode, a polyolefin-based porous separator coated with inorganic particles (Al2O3), and a negative electrode were sequentially stacked to prepare an electrode assembly.

[0117] The electrode assembly thus assembled was placed in a battery case, and 6 mL of the prepared non-aqueous electrolyte was then poured into the battery case to prepare a lithium secondary battery.

[0118] Example 2. A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 1.0 wt % of the compound represented by Formula 1a and other additives, 0.5 wt % of VEC, 1.0 wt % of PS, 5.0 wt % of FEC, 1.0 wt % of SN, and 0.5 wt % of LiODFB, were added to prepare a non-aqueous electrolyte (see Table 1 below).

[0119] Example 3. A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 5.0 wt % of the compound represented by Formula 1a and other additives, 0.5 wt % of VEC, 1.0 wt % of PS, 5.0 wt % of FEC, 1.0 wt % of SN, and 0.5 wt % of LiODFB, were added to prepare a non-aqueous electrolyte (see Table 1 below).

[0120] Example 4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 11.0 wt % of the compound represented by Chemical Formula 1a and other additives, 0.5 wt % of VEC, 1.0 wt % of PS, 5.0 wt % of FEC, 1.0 wt % of SN, and 0.5 wt % of LiODFB, were added to prepare a non-aqueous electrolyte (see Table 1 below).

[0121] Example 5. A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 1.0 wt % of the compound represented by Chemical Formula 1b and other additives, 0.5 wt % of VEC, 1.0 wt % of PS, 5.0 wt % of FEC, 1.0 wt % of SN, and 0.5 wt % of LiODFB, were added to prepare a non-aqueous electrolyte (see Table 1 below).

[0122] Example 6. A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 1.0 wt % of the compound represented by Chemical Formula 1c and other additives, 0.5 wt % of VEC, 1.0 wt % of PS, 5.0 wt % of FEC, 1.0 wt % of SN, and 0.5 wt % of LiODFB, were added to prepare a non-aqueous electrolyte (see Table 1 below).

[0123] Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that LiPF6 was dissolved in a non-aqueous organic solvent to a concentration of 1.0 M, and then 0.5 wt % VEC, 1.0 wt % PS, 5.0 wt % FEC, 1.0 wt % SN, and 0.5 wt % LiODFB were added as other additives to prepare a non-aqueous electrolyte solution (see Table 1 below).

[0124] Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte solution was manufactured by adding a compound represented by the following Chemical Formula 2 instead of the compound represented by Chemical Formula 1a (see Table 1 below).

[0125] [ka]

[0126] Comparative Example 3. A lithium secondary battery was manufactured in the same manner as in Example 2, except that the compound represented by Chemical Formula 2 was added instead of the compound represented by Chemical Formula 1a to prepare a non-aqueous electrolyte solution (see Table 1 below).

[0127] [Table 1]

[0128] Meanwhile, in Table 1, the abbreviations of the compounds have the following meanings. EC: Ethylene carbonate PC: Propylene carbonate EP: Ethyl propionate PP: Propyl propionate

[0129] Experimental Example Experimental example 1: Evaluation of interface resistance The lithium secondary batteries prepared in Examples 1 to 6 and the lithium secondary batteries prepared in Comparative Examples 1 to 3 were discharged at room temperature (25° C.) at 5C for 10 seconds to SOC 50%, and then the initial interface resistance was calculated from the voltage drop observed at that time using VMP3 (manufactured by Biologics). The results are shown in Table 2 below as a percentage relative to the secondary battery of Comparative Example 1.

[0130] Experimental example 2: Room temperature discharge capacity A constant current was applied to each of the lithium secondary batteries manufactured in Examples 1 to 3, 5, and 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 at room temperature (25° C.) at a rate of 0.2 C by a CC-CV (constant current-constant voltage) method up to 4.45 V, and then the current was controlled at a constant voltage of 4.45 V. During discharge, the capacity (PNE-0506 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5 V, 6 A)) obtained by cutting off at 3.0 V by a CC (constant current) method at a rate of 0.2 C is shown in Table 2 below.

[0131] Experimental example 3. Capacity retention rate at room temperature Each of the lithium secondary batteries manufactured in Examples 1 to 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 was charged at a 2C rate under constant current / constant voltage conditions at 25° C. up to 4.45 V, and then discharged at a 1C rate under constant current conditions down to 3.0 V, which constituted one cycle. The discharge capacity and resistance after one cycle were measured using a PNE-0506 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5 V, 6 A).

[0132] Thereafter, 200 cycles of charge and discharge were performed under the same cycle conditions as above, and then the capacity retention rate (%) was calculated according to the following formula 1, and the results are shown in Table 2 below.

[0133] [Formula 1] Capacity retention rate (%) = (discharge capacity after 200 cycles / discharge capacity after 1 cycle) x 100

[0134] [Table 2]

[0135] Referring to Table 2 above, it can be seen that the secondary batteries of Examples 1 to 3, 5 and 6 of the present invention have improved interface resistance (%) at room temperature (25°C), discharge capacity (mAh), and capacity retention rate (%) after 200 cycles compared to the secondary batteries of Comparative Examples 1 to 3.

[0136] On the other hand, the secondary battery of Example 4, which contains a slightly larger amount of additive, exhibits increased resistance and side reactions due to the additive inside the battery, and as a result, compared to the secondary batteries of Examples 1 to 3, 5, and 6, it is observed that the interfacial resistance (%) is increased and the capacity retention rate (%) is relatively decreased.

[0137] Experimental Example 4: Low-temperature discharge capacity A constant current was applied to each of the lithium secondary batteries prepared in Examples 1 to 6 and Comparative Examples 1 to 3 at a low temperature (10° C.) at a rate of 0.2 C by a CC-CV (constant current-constant voltage) method up to 4.45 V, and then the current was controlled at a constant voltage of 4.45 V. During discharge, the discharge capacity was measured using a PNE-0506 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5 V, 6 A) with a cut-off at 3.0 V by a CC (constant current) method at a rate of 0.2 C, and the results are shown in Table 3 below.

[0138] [Table 3]

[0139] Referring to Table 3, it can be seen that the secondary batteries of Examples 1 to 6 of the present invention have a discharge capacity (mAh) of 4235 mAh or more at low temperature, which is improved compared to the secondary batteries of Comparative Examples 1 to 3.

[0140] Experimental example 5.2C charging potential The lithium secondary batteries manufactured in Examples 1 to 3, 5, and 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 were each subjected to CC-CV charging at a rate of 2C at a low temperature (10°C) and the capacity at the beginning of charging (up to SOC 20%) was measured using a PNE-0506 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5V, 6A). The 2C charging potential (average voltage) at the beginning of charging was calculated according to the following Equation 2, and the results are shown in Table 4 below.

[0141] [Formula 2] 2C charging potential (average voltage) (V) = charging energy up to SOC 20% (mWh) / (capacity at SOC 20% (mAh))

[0142] [Table 4]

[0143] Referring to Table 4, the secondary batteries of Examples 1 to 3, 5, and 6 had a 2C charge potential of 4.10 V or less at low temperature, and thus could be charged at a lower potential than the secondary batteries of Comparative Examples 1 to 3.

[0144] Meanwhile, the secondary battery of Example 2 had a lower 2C charging potential than the secondary battery of Example 1, which means that the overpotential was reduced. This result shows that the effect of reducing resistance was further improved when the additive content was 1.0 wt % compared to when the additive content was 0.1 wt %.

[0145] On the other hand, the secondary battery of Example 3, in which the additive content was 5.0 wt %, was found to have an increased coating thickness, a relatively higher resistance, and a slightly higher potential compared to the secondary batteries of Examples 1 and 2.

[0146] Meanwhile, referring to Table 4, it can be seen that the secondary battery of Example 1, in which the additive content is 0.1 wt%, has a relatively small amount of fluorocarbon component in the SEI constituents, and therefore the effect of reducing resistance is relatively slightly reduced compared to the secondary battery of Example 2, in which the additive content is 1.0 wt%. In other words, it can be seen that the resistance of the SEI film is reduced due to the increased content of fluorocarbon component, which has low surface energy and is favorable for Li diffusion, during the formation of the SEI film.

Claims

1. The present invention includes a lithium salt, a non-aqueous organic solvent, and a compound represented by the following chemical formula 1: The compound represented by Chemical Formula 1 is contained in an amount of 0.01 wt % to 10.0 wt % based on the total weight of the nonaqueous electrolyte for a lithium secondary battery: 【Chemistry 1】 (In the above Chemical Formula 1, R １ and R ２ are each independently an alkylene group having 1 to 10 carbon atoms, R ３ is an alkyl group having 1 to 20 carbon atoms substituted with one or more fluorine atoms.

2. In the compound represented by the above formula 1, R １ and R ２ are each independently an alkylene group having 1 to 5 carbon atoms; R ３ 2. The nonaqueous electrolyte for a lithium secondary battery according to claim 1, wherein is an alkyl group having 3 to 20 carbon atoms and substituted with one or more fluorine atoms.

3. In the compound represented by the above formula 1, R １ and R ２ are each independently an alkylene group having 1 to 3 carbon atoms; R ３ 2. The nonaqueous electrolyte for a lithium secondary battery according to claim 1, wherein is an alkyl group having 3 to 15 carbon atoms and substituted with one or more fluorine atoms.

4. In the compound represented by the above formula 1, R ３ 2. The nonaqueous electrolyte for a lithium secondary battery according to claim 1, wherein is an alkyl group having 3 to 10 carbon atoms and substituted with one or more fluorine atoms.

5. The nonaqueous electrolyte for a lithium secondary battery according to claim 1, wherein the compound represented by Chemical Formula 1 is at least one of compounds represented by the following Chemical Formulas 1a to 1c: 【Chemistry 2】 【Chemistry 3】 【Chemistry 4】

6. 2. The non-aqueous electrolyte for a lithium secondary battery according to claim 1, wherein the compound represented by Formula 1 is contained in an amount of 0.1 to 6.0 wt % based on the total weight of the non-aqueous electrolyte for a lithium secondary battery.

7. 2. The nonaqueous electrolyte solution for a lithium secondary battery according to claim 1, further comprising at least one other additive selected from the group consisting of halogen-substituted or unsubstituted carbonate-based compounds, sultone-based compounds, sulfate-based compounds, phosphate-based or phosphite-based compounds, borate-based compounds, nitrile-based compounds, amine-based compounds, silane-based compounds, and lithium salt-based compounds.

8. a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator interposed between the negative electrode and the positive electrode; A lithium secondary battery comprising the nonaqueous electrolyte solution for a lithium secondary battery according to claim 1 .

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