Non-aqueous electrolyte solution for lithium secondary battery and lithium ion secondary battery containing the same

Abstract

The present invention relates to a non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery containing the same. More specifically, the present invention relates to a non-aqueous electrolyte solution for a lithium secondary battery and a lithium secondary battery containing the same, wherein the non-aqueous electrolyte solution comprises: a lithium salt; an organic solvent; a first additive; and a second additive, wherein the first additive is a compound represented by Chemical Formula 1, and the second additive is a compound represented by Chemical Formula 2.

Description

Technical Field

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2020-0131411, filed on October 12, 2020, and the entire contents of the Korean Patent Application are incorporated herein by reference.

[0002] The present invention relates to a non-aqueous electrolyte solution for a secondary battery, and more particularly to a non-aqueous electrolyte solution for a secondary battery and a secondary battery comprising the same, wherein the non-aqueous electrolyte solution can store LiPF at high temperatures. 6 Non-aqueous electrolyte solutions of lithium salts improve volumetric and resistive properties. Background Art

[0003] Recently, interest in developing energy storage technology has been increasing, and as the application fields are expanding to mobile phones, cameras and laptop PCs, as well as electric vehicles, efforts in research and development of electrochemical elements are currently being put into practice.

[0004] Among electrochemical devices, interest in developing secondary batteries has been increasing, and in particular, lithium secondary batteries developed in the 1990s have attracted much attention due to their advantages of high operating voltage and large energy density.

[0005] In the case of a lithium secondary battery system, unlike the early days when lithium metal was directly applied to the system, a transition metal oxide containing lithium is used as a positive electrode material, and a carbon-based material (such as graphite and alloy-based materials such as silicon) is applied to the negative electrode as a negative electrode material. In this way, a system that does not directly use lithium metal in a battery is currently implemented.

[0006] This lithium secondary battery is composed of a positive electrode, a negative electrode capable of storing lithium, an electrolyte solution for transferring lithium ions, and a separator, wherein the positive electrode is composed of a transition metal oxide containing lithium. In this article, the electrolyte solution is referred to as a component that significantly affects the stability and safety of the battery, and a large amount of research has been conducted on the electrolyte solution.

[0007] The electrolyte solution for lithium secondary batteries consists of a lithium salt, an organic solvent that dissolves the lithium salt, and a functional additive. In this context, it is important to appropriately select these components in order to improve the electrochemical characteristics of the battery. Examples of lithium salts currently used include LiPF 6 , LiBF 4 、LiFSI(Lithium Fluorosulfonyl Imide、LiN(SO 2 F) 2 )、LiTFSI(Lithium bis(trifluoromethanesulfonyl)imide、LiN(SO 2 CF 3 ) 2) or LiBOB (lithium bis(oxalato)borate, LiB(C 2 O 4 ) 2 ), and examples of the organic solvent include carbonate-based organic solvents, ester-based organic solvents, or ether-based organic solvents.

[0008] In the case of such lithium secondary batteries, the increase in resistance and the decrease in capacity during charging / discharging and storage at high temperatures present a big problem in terms of performance degradation. Here, one of the causes of this problem is the side reaction that occurs due to degradation at high temperatures, especially the degradation caused by the decomposition of salts at high temperatures. If the byproducts of the salts are activated and then decompose the film formed on the surface of the positive and negative terminals, the passivation ability of the film may decrease, thereby causing additional decomposition and self-discharge of the electrolyte solution.

[0009] LiPF 6 Mainly used as lithium salt in non-aqueous electrolyte solution. 6 - It is easily affected by heat, so when the battery is exposed to high temperature, it will produce PF due to thermal decomposition. 5 Lewis acids, and it is known that this PF 5 The carbonate-based organic solvent itself is decomposed and HF is generated, thereby accelerating the dissolution of the transition metal of the positive electrode active material.

[0010] In the case of lithium-ion batteries, especially the electrode material of the negative electrode, a graphite-based negative electrode is generally used. In the case of graphite, the operating potential is equal to or less than 0.3 V (relative to Li / Li+), and the currently used electrolyte solution undergoes reduction and decomposition. Such reduction decomposition products allow lithium ions to penetrate, but the additional decomposition of the electrolyte solution forms a solid electrolyte interface (SEI) film.

[0011] However, if the SEI film fails to have a passivation ability sufficient to suppress the additional decomposition of the electrolyte solution, the electrolyte solution is additionally decomposed during storage, and the charged graphite self-discharges, thereby showing a phenomenon in which the potential of the entire battery decreases. Therefore, in order to maintain the passivation ability of the SEI at high temperatures, an additive that can remove LiPF, a decomposition product generated due to heat / moisture, is urgently needed. 6 HF, PF 5 etc., or a stable film can be formed on the SEI film formed on the positive / negative electrode.

[0012] In order to suppress the deterioration at high temperature, Japanese Patent Application No. 2002-329528 discloses a technology for suppressing gas generation at high temperature using an unsaturated sultone compound, and Japanese Patent Publication No. 2001-006729 discloses a technology for improving high temperature storage characteristics by using a carbonate compound containing a vinyl group. However, these conventional technologies do not effectively remove PF 5 , thus failing to adequately address existing problems.

[0013] Therefore, a method is needed to effectively remove the 6 PF generated by thermal decomposition of lithium-like salts 5 Technology of non-aqueous electrolyte solutions. Summary of the invention

[0014] Technical issues

[0015] It is believed that the present invention solves at least some of the above problems. For example, one aspect of the present invention provides a non-aqueous electrolyte solution and a lithium secondary battery, wherein the non-aqueous electrolyte solution can effectively remove the electrolyte that may be present in the presence of LiPF. 6 PF generated in lithium salt electrolyte solution 5 , and the lithium secondary battery has improved high-temperature storage characteristics through the non-aqueous electrolyte solution.

[0016] Technical Solution

[0017] The non-aqueous electrolyte solution for lithium secondary batteries of the present invention includes: a lithium salt; an organic solvent; a first additive; and a second additive. Herein, the first additive is a compound represented by the following Chemical Formula 1, and the second additive is a compound represented by the following Chemical Formula 2.

[0018] [Chemical formula 1]

[0019]

[0020] Wherein, in the above chemical formula 1,

[0021] R 1 To R 3 Each is hydrogen or an alkyl group having 1 to 3 carbon atoms.

[0022] [Chemical formula 2]

[0023]

[0024] Herein, L is an alkylene group having 1 to 10 carbon atoms.

[0025] In one embodiment of the present invention, the amount of the first additive contained in the electrolyte solution corresponds to 0.05 wt % to 3 wt % of the total weight of the electrolyte solution, and the amount of the second additive contained in the electrolyte solution corresponds to 0.05 wt % to 5 wt % of the total weight of the electrolyte solution.

[0026] In one embodiment of the present invention, the first additive and the second additive are contained in the electrolyte solution in an amount corresponding to 0.3 wt % to 3 wt % of the total weight of the electrolyte solution.

[0027] In one embodiment of the present invention, the weight ratio of the first additive to the second additive is 2:8 to 7:3, and may preferably be 3:7 to 6:4.

[0028] In one embodiment of the present invention, the compound represented by Chemical Formula 1 is a compound represented by the following Chemical Formula 1a.

[0029] [Chemical formula 1a]

[0030]

[0031] In one embodiment of the present invention, the compound represented by Chemical Formula 2 is a compound represented by the following Chemical Formula 2a.

[0032] [Chemical formula 2a]

[0033]

[0034] In one embodiment of the present invention, the non-aqueous electrolyte solution for a lithium secondary battery further comprises: at least one selected from the group consisting of a halogen-substituted or unsubstituted cyclic carbonate compound, a propionate compound, a nitrile compound, a phosphate compound, a borate compound, a sultone compound, a sulfate compound and a lithium salt compound, and more preferably further comprises vinylene carbonate (VC) and propane sultone (PS) as additives.

[0035] In one embodiment of the present invention, a weight ratio of the total weight of the first additive and the second additive to the total weight of vinylene carbonate (VC) and propane sultone (PS) is 1:1 to 1:4, and may preferably be 1:1 to 1:3.

[0036] In one embodiment of the present invention, the lithium salt comprises LiPF 6 .

[0037] The lithium secondary battery of the present invention includes the above-mentioned non-aqueous electrolyte solution for lithium secondary batteries.

[0038] Beneficial effects

[0039] The additive included in the nonaqueous electrolyte solution according to the present invention can prevent a rapid increase in resistance under high temperature conditions and maintain a constant capacity by effectively removing byproducts generated from lithium salts, thereby improving high temperature characteristics.

[0040] Furthermore, since the nonaqueous electrolyte solution for a lithium secondary battery can form a strong SEI film on the negative electrode, a lithium secondary battery can be provided that can easily control the amount of gas generated due to side reactions during high-temperature storage while maintaining excellent resistance characteristics. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below. The terms and words used in this specification and claims should not be interpreted as limited to common or dictionary terms, and the inventors can appropriately define the concepts of the terms in order to best describe their inventions. The terms and words should be interpreted as meanings and concepts consistent with the technical ideas of the present invention.

[0042] In addition, in the term "carbon number a to b" in the present specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include a to b carbon atoms. For example, "alkylene having carbon number 1 to 5" refers to an alkylene having 1 to 5 carbon atoms, that is, -CH 2 -、-CH 2 CH 2 -、-CH 2 CH 2 CH 2 -、-CH 2 (CH 2 )CH-、-CH(CH 2 )CH 2 - and -CH(CH 2 )CH 2 CH 2 -wait.

[0043] An alkylene group refers to a divalent unsaturated hydrocarbon group.

[0044] Non-aqueous electrolyte solutions for lithium secondary batteries

[0045] In one embodiment of the present invention, the present invention provides a non-aqueous electrolyte solution for a lithium secondary battery, the non-aqueous electrolyte solution comprising: a lithium salt; an organic solvent; a first additive; and a second additive, wherein the first additive is a compound represented by the following Chemical Formula 1, and the second additive is a compound represented by the following Chemical Formula 2.

[0046] [Chemical formula 1]

[0047]

[0048] In this paper, R 1 To R 3 Each is hydrogen or an alkyl group having 1 to 3 carbon atoms.

[0049] [Chemical formula 2]

[0050]

[0051] Herein, L is an alkylene group having 1 to 10 carbon atoms.

[0052] (1) Lithium salt

[0053] In the non-aqueous electrolyte solution for a lithium secondary battery according to an embodiment of the present invention, the lithium salt includes LiPF 6 , and in addition to LiPF 6 In addition, those commonly used in electrolyte solutions for lithium secondary batteries can be used without limitation. For example, + as a cation of the lithium salt, and may include at least one selected from the group consisting of: F - , Cl - Br - ,I - 、NO 3 - 、N(CN) 2 - , ClO 4 - , BF 4 - , B 10 Cl 10 - PF 6 - CF 3 SO 3 - , CH 3 CO 2 - CF 3 CO 2 - , AsF 6 - , SbF 6 - 、AlCl 4 - 、AlO 4 - , CH 3 SO 3 - , BF 2 C 2 O 4- , BC 4 O 8 - , PF 4 C 2 O 4 - , PF 2 C 4 O 8 - , (CF 3 ) 2 PF 4 - , (CF 3 ) 3 PF 3 - , (CF 3 ) 4 PF 2 - , (CF 3 ) 5 PF - , C 4 F 9 SO 3 - , CF 3 CF 2 SO 3 - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3 - , SCN - and (CF 3 CF 2 SO 2 )2 N - .

[0054] Specifically, the lithium salt may include a lithium salt selected from the group consisting of LiPO 2 F 2 、LiCl、LiBr、LiI、LiClO 4 , LiBF 4 , LiB 10 Cl 10 、LiPF 6 、LiCF 3 SO 3 、LiCH 3 CO 2 、LiCF 3 CO 2 、LiAsF 6 、LiSbF 6 、LiAlCl 4 、LiAlO 4 、LiCH 3 SO 3 、LiFSI(lithium fluorosulfonyl imide, LiN(SO 2 F) 2 )、LiTFSI(Lithium bis(trifluoromethanesulfonyl)imide、LiN(SO 2 CF 3 ) 2 ) and LiBETI (lithium bis(perfluoroethanesulfonyl)imide, LiN(SO 2 C 2 F 5 ) 2 ) or a combination of two or more selected from the group consisting of: 6 , LiBF 4 、LiPO 2 F 2 、LiCH 3 CO 2 、LiCF 3 CO 2 、LiCH 3 SO 3 , LiFSI, LiTFSI and LiN(C 2 F 5 SO 2 ) 2 .

[0055] The lithium salt may be appropriately changed within a generally available range, but specifically, 0.1 M to 3 M of lithium salt may be included in the electrolyte solution, more specifically 0.8 M to 2.5 M of lithium salt. If the concentration of the lithium salt exceeds 3 M, the viscosity of the non-aqueous electrolyte solution increases, the lithium ion transfer effect decreases, and the wettability of the non-aqueous electrolyte solution decreases, so it is difficult to form a SEI film having a uniform thickness on the surface of the electrode.

[0056] (2) Organic solvents

[0057] The organic solvent can minimize the decomposition caused by oxidation reaction during the charge / discharge of the secondary battery, and there is no limitation on the type of the organic solvent as long as it can show the desired characteristics together with the additive. For example, carbonate organic solvents, ether organic solvents or ester organic solvents can be used alone or in combination of two or more.

[0058] The carbonate organic solvent in the organic solvent may include at least one of a cyclic carbonate organic solvent and a linear carbonate organic solvent. Specifically, the cyclic carbonate organic solvent 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 (VC) and fluoroethylene carbonate (FEC), and may specifically include a mixed solvent of ethylene carbonate with a high dielectric constant and propylene carbonate with a relatively low melting point compared to ethylene carbonate.

[0059] In addition, the straight-chain carbonate organic solvent is a solvent having low viscosity and a low dielectric constant, and may include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate, and may specifically include ethyl methyl carbonate (EMC) and diethyl carbonate (DEC).

[0060] In addition, as the ether organic solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, and ethyl propyl ether may be used, or a mixture of two or more thereof may be used, but is not limited thereto.

[0061] The ester organic solvent may be at least one selected from the group consisting of linear ester organic solvents and cyclic ester organic solvents.

[0062] At this time, one or a mixture of two or more selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate and butyl propionate may be used as the linear ester organic solvent, but the present invention is not limited to these examples.

[0063] As the cyclic ester organic solvent, one or a mixture of two or more selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone may be used, but the present invention is not limited to these examples.

[0064] Cyclic carbonate organic solvents with high viscosity that can easily dissociate lithium salts in the electrolyte due to high dielectric constant can be used as organic solvents. In addition, in order to manufacture an electrolyte with higher conductivity, linear carbonate compounds (such as dimethyl carbonate and diethyl carbonate) and linear ester compounds with low viscosity and low dielectric constant can be mixed with cyclic carbonate organic solvents in a suitable ratio.

[0065] More specifically, the organic solvent may be obtained by mixing a cyclic carbonate compound with a linear carbonate compound, and a weight ratio of the cyclic carbonate compound to the linear carbonate compound may be 10:90 to 70:30.

[0066] (3) First additive

[0067] In addition, the nonaqueous electrolyte solution for a secondary battery of the present invention may further include a compound represented by the following Chemical Formula 1 as a first additive.

[0068] [Chemical formula 1]

[0069]

[0070] (In Chemical Formula 1, R 1 To R 3 are each hydrogen or an alkyl group having 1 to 3 carbon atoms).

[0071] Since the compound represented by Chemical Formula 1 contains a functional group as a Lewis base including a nitrogen element in the structure, it cannot suppress the decomposition of anions, but can remove Lewis acids such as HF and PF. 5 , which are decomposition products generated due to the decomposition of anions. Therefore, degradation attributed to the chemical reaction of the film generated by the Lewis acid on the surface of the positive electrode or the negative electrode can be suppressed. In particular, the compound of Chemical Formula 1 can effectively remove the Lewis acid, which is a decomposition product of the lithium salt, through the imidazole functional group. As a result, since the decomposition of the additional electrolyte solution of the battery caused by the destruction of the membrane can be prevented by preventing the degradation of the membrane, the self-discharge of the battery can be finally suppressed.

[0072] In one embodiment of the present invention, as the compound represented by Chemical Formula 1, the compound represented by the following Chemical Formula 1a is effective in removing PF 5 More effective.

[0073] [Chemical formula 1a]

[0074]

[0075] (4) Second additive

[0076] In addition, the nonaqueous electrolyte solution for a secondary battery of the present invention may further include a compound represented by the following Chemical Formula 2 as a second additive.

[0077] [Chemical formula 2]

[0078]

[0079] Herein, L is an alkylene group having 1 to 10 carbon atoms.

[0080] Since the sulfonate compound of Chemical Formula 2 can reduce byproducts generated by side reactions with the electrode and the electrolyte solution by forming a stable protective film on the electrode, it is possible to suppress resistance increase or gas generation caused by additional electrode side reactions.

[0081] In one embodiment of the present invention, the compound represented by Chemical Formula 2 is most preferably a compound represented by the following Chemical Formula 2a.

[0082] [Chemical formula 2a]

[0083]

[0084] In a specific example of the present invention, the amount of the first additive contained in the electrolyte solution corresponds to 0.05% to 3% by weight of the total weight of the electrolyte solution, and preferably corresponds to 0.3% to 3% by weight of the total weight of the electrolyte solution. In addition, the amount of the second additive contained in the electrolyte solution corresponds to 0.05% to 5% by weight of the total weight of the electrolyte solution, and preferably corresponds to 0.3% to 3% by weight of the total weight of the electrolyte solution.

[0085] In addition, the weight ratio of the first additive to the second additive may be 2:8 to 7:3, preferably 3:7 to 6:4, and more preferably 3:7 to 5:5.

[0086] When the content of the first additive and the second additive is within the above range, a secondary battery with improved performance can be manufactured. For example, within the above range, byproducts can be effectively removed and metal dissolution can be effectively suppressed, thereby improving the effect of controlling the increase in resistance of the film by decomposition of the additive.

[0087] (5) Additional additives

[0088] The non-aqueous electrolyte solution of the present invention may also include additional additives, which, in addition to the effects exhibited by the above-mentioned mixed additives when used together with the above-mentioned mixed additives, can form a stable film on the surface of the negative electrode and the positive electrode without significantly increasing the initial resistance, or inhibit the decomposition of the solvent in the non-aqueous electrolyte solution, and act as a complementary element for improving the mobility of lithium ions.

[0089] For example, an additive for forming a SEI film capable of forming a stable film on the surfaces of the positive electrode and the negative electrode terminals may be used as the additional additive.

[0090] Specifically, as an additive for forming an SEI film, the non-aqueous electrolyte solution for a lithium secondary battery may also include: at least one selected from the group consisting of halogen-substituted or unsubstituted cyclic carbonate compounds, propionate compounds, nitrile compounds, phosphate compounds, borate compounds, sultone compounds, sulfate compounds and lithium salt compounds.

[0091] Specifically, the halogen-substituted cyclic carbonate compound or the halogen-unsubstituted cyclic carbonate compound may improve the durability of a battery by forming a stable SEI film on the surface of a negative electrode during battery activation.

[0092] The example of this halogen-substituted cyclic carbonate compound can be fluoroethylene carbonate (FEC). The example of the halogen-unsubstituted cyclic carbonate compound can be vinylene carbonate (VC) and vinyl ethylene carbonate (VEC), but vinylene carbonate (VC) is preferred in terms of compatibility with the first additive and the second additive.

[0093] The content of the halogen-substituted cyclic carbonate compound or the halogen-unsubstituted cyclic carbonate compound may correspond to 5% by weight or less of the total weight of the non-aqueous electrolyte solution. When the content of the cyclic carbonate compound in the non-aqueous electrolyte solution exceeds 5% by weight, the battery swelling inhibition performance and initial resistance may be deteriorated.

[0094] When the nitrile compound is used together with the above-mentioned mixed additive, the effects such as the improvement of high temperature characteristics can be expected by stabilizing the positive / negative electrode film. That is, it can act as a supplementary element when forming the negative electrode SEI film, inhibit the decomposition of the solvent in the electrolyte, and improve the mobility of lithium ions. Examples of nitrile compounds may include at least one selected from the group consisting of: succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, octanonitrile, heptonitrile, cyclopentanenitrile, cyclohexanenitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, benzonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, 1,4-dicyano-2-butene, glutaronitrile, 1,6-hexanetrinitrile and heptane dinitrile.

[0095] The content of the nitrile compound may correspond to 8 wt% or less of the total weight of the non-aqueous electrolyte solution. When the total content of the nitrile compound in the non-aqueous electrolyte solution exceeds 8 wt%, the resistance increases due to the increase of the film formed on the electrode surface, thereby deteriorating the performance of the battery.

[0096] In addition, since the phosphate compound stabilizes the PF6 anion in the electrolyte solution and helps to form the positive and negative electrode films, the durability of the battery is improved. Some examples of the phosphate compound may include at least one selected from the group consisting of lithium difluorophosphate (LiDFP, LiPO 2 F 2 ), tetramethyltrimethylsilyl lithium phosphate, trimethylsilyl phosphite (TMSPi), trimethylsilyl phosphate (TMSPa), di(prop-2-yn-1-yl)ethyl phosphate, allyl diphosphate, tri(2,2,2-trifluoroethyl) phosphate (TFEPa) and tri(trifluoroethyl) phosphite, and the content of the phosphate ester / salt compound can correspond to less than 3 weight % of the total weight of the non-aqueous electrolyte solution.

[0097] Borate compounds can improve the mobility of lithium ions by promoting ion pair separation, reduce the interfacial resistance of the SEI film, and can solve problems such as hydrofluoric acid gas generation by dissociating materials such as LiF, which is generated during battery reactions and is not easily separated. LiBOB, LiB(C 2 O 4 ) 2 , lithium oxalyldifluoroborate, or tetramethyltrimethylsilylborate (TMSB) may be used as the borate compound, and the content of the borate compound may be equal to or less than 3 wt % of the total weight of the nonaqueous electrolyte solution.

[0098] At least one compound selected from the group consisting of propane sultone (PS), 1,4-butene sultone, ethane sultone, 1,3-propene sultone and 1-methyl-1,3-propene sultone may be used as the sultone compound, and the content of the sultone compound may be 0.3 wt % to 5 wt %, particularly 1 wt % to 5 wt % of the total weight of the non-aqueous electrolyte solution. Among them, 1,3-propane sultone (PS) is more preferred in terms of compatibility with the first additive and the second additive.

[0099] When the content of the sultone compound in the non-aqueous electrolyte solution exceeds 5 wt %, an excessively thick film may be formed on the surface of the electrode, thereby increasing resistance and deteriorating output, and resistance may increase due to a large amount of additives in the non-aqueous electrolyte solution, thereby deteriorating output characteristics.

[0100] In addition, the lithium salt compound is a compound different from the lithium salt contained in the non-aqueous electrolyte solution. Some examples of the lithium salt compound include one or more selected from the group consisting of lithium methyl sulfate, lithium ethyl sulfate, 2-trifluoromethyl-4,5-dicyanoimidazole lithium, lithium tetrafluorooxalate phosphate, LiODFB and LiBF 4 , and the content of the lithium salt compound may be equal to or less than 3 weight % of the total weight of the non-aqueous electrolyte solution.

[0101] The content of the above additional additives may be 15 wt % or less, and specifically 0.01 wt % to 10 wt %, and preferably 0.1 wt % to 5.0 wt %, based on the total weight of the electrolyte solution.

[0102] A mixture of two or more may be used as an additional additive, and among the above-mentioned additional additives, a mixture of vinylene carbonate (VC) and propane sultone (PS), and a non-aqueous electrolyte solution comprising the first additive and the second additive exhibit a more excellent effect of improving characteristics after high-temperature storage.

[0103] The weight ratio of the total weight of the first additive and the second additive to the total weight of vinylene carbonate (VC) and propane sultone (PS) may be 1:1 to 1:4, more preferably 1:1 to 1:3, and most preferably 4:5 to 2:5.

[0104] When the content of the additive for forming the SEI film is less than 0.01 wt%, the high temperature storage characteristics and gas reduction effect intended to be achieved by the additive are very weak, and if the content of the additive for forming the SEI film exceeds 15 wt%, side reactions may occur excessively. Specifically, when a large amount of additives for forming the SEI film are added, they may not be fully decomposed and may remain precipitated or unreacted in the electrolyte solution at room temperature. Therefore, the resistance increases, and the life characteristics of the secondary battery may deteriorate.

[0105] Lithium secondary battery

[0106] Furthermore, in an embodiment of the present invention, there is provided a lithium secondary battery including the nonaqueous electrolyte solution for a secondary battery of the present invention.

[0107] The lithium secondary battery of the present invention can be manufactured by injecting the non-aqueous electrolyte solution of the present invention into an electrode assembly, which is obtained by sequentially stacking a positive electrode, a negative electrode, and a separator inserted between the positive electrode and the negative electrode. At this time, the positive electrode, the negative electrode, and the separator commonly used in the manufacture of lithium secondary batteries can be used as the positive electrode, the negative electrode, and the separator forming the electrode assembly.

[0108] Furthermore, the positive electrode and the negative electrode forming the lithium secondary battery of the present invention can be manufactured and used in a general method.

[0109] (1) Positive electrode

[0110] The positive electrode can be manufactured by forming a positive electrode mixture layer on a positive electrode current collector. The positive electrode mixture layer can be formed by coating a positive electrode slurry including a positive electrode active material, a binder, a conductive material, and a solvent on the positive electrode current collector, then drying the slurry and rolling the positive electrode current collector.

[0111] The positive electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel whose surface is treated with carbon, nickel, titanium, or silver, etc.

[0112] The positive electrode active material is a compound capable of reversibly inserting and extracting lithium, and can specifically include a lithium metal oxide containing lithium and at least one metal (such as cobalt, manganese, nickel, or aluminum). Specifically, some examples of the lithium metal oxide can include lithium-nickel-manganese-cobalt-based oxides (for example, Li(Ni p Co q Mn r1 )O 2 (In this text, 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O 4 (In this text, 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.) or lithium-nickel-cobalt-transition metal (M) oxides (for example, Li(Ni p2 Co q2 Mn r3 M s2 )O 2 (In this text, M is selected from one of the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, and B, and p2, q2, r3, and s2 are atomic fractions of respective independent elements, and 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, p2 + q2 + r3 + s2 = 1), etc.).

[0113] Examples of the positive electrode active material can include Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O 2 、Li(Ni 0.35 Mn 0.28 Co 0.37 )O 2 、Li(Ni0.6 Mn 0.2 Co 0.2 ) 2 、Li(Ni 0.5 Mn 0.3 Co 0.2 ) 2 、Li(Ni 0.7 Mn 0.15 Co 0.15 ) 2 、Li(Ni 0.8 Mn 0.1 Co 0.1 ) 2 Or Li(Ni 0.8 Co 0.15 Al 0.05 ) 2 .

[0114] The content of the positive electrode active material may correspond to 90 to 99 wt %, specifically 93 to 99 wt %, based on the total weight of solids in the positive electrode slurry.

[0115] The binder is added in an amount of 1 wt % to 30 wt % based on the total weight of the solids in the positive electrode slurry as a component that helps to bind between the active material and the conductive material and to the current collector. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, fluororubber and various copolymers.

[0116] Such a conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and examples thereof include: carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black; graphite powder such as natural graphite or artificial graphite, or graphite in which the crystal structure has been well developed; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride, aluminum and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives, etc.

[0117] The conductive material is generally added in an amount of 0.5 wt % to 20 wt % based on the total weight of solids in the positive electrode slurry.

[0118] The solvent may include an organic solvent, such as NMP (N-methyl-2-pyrrolidone), and its amount may be such that the desired viscosity is obtained when the positive electrode active material and the optional binder and the conductive material are included. For example, the concentration of the solid in the slurry including the positive electrode active material and the optional binder and the conductive material may be 30% to 90% by weight, preferably 40% to 80% by weight.

[0119] (2) Negative electrode

[0120] The negative electrode may be manufactured by forming a negative electrode mixture layer on a negative electrode current collector. The negative electrode mixture layer may be formed by coating a slurry including a negative electrode active material, a binder, a conductive material, a solvent, etc. on the negative electrode current collector, followed by drying and roll pressing.

[0121] The negative electrode current collector is usually made into a thickness of 3 to 500 microns. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and examples thereof include copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel whose surface has been treated with carbon, nickel, titanium or silver, aluminum-cadmium alloy, etc. In addition, as with the positive electrode current collector, fine concavoconvex objects may be formed on the surface to enhance the binding force of the negative electrode active material, and it may be used in various forms, such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

[0122] In addition, the negative electrode active material may include at least one selected from the group consisting of lithium metal, carbon materials capable of reversibly intercalating / deintercalating lithium ions, metals or alloys of metals and lithium, metal oxides, materials capable of doping and dedoping lithium, and transition metal oxides.

[0123] Any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used as a carbon material capable of reversibly inserting / deinserting lithium ions, and its representative examples may include crystalline carbon, amorphous carbon, or a combination thereof. Some examples of crystalline carbon may include amorphous, flaky, spherical, or fibrous natural graphite or artificial graphite, and some examples of amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbide, and fired coke.

[0124] 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 lithium and these metals can be used.

[0125] As the metal oxide, PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb2 O 3 、Sb 2 O 4 、Sb 2 O 5 、GeO、GeO 2 、Bi 2 O 3 、Bi 2 O 4 、Bi 2 O 5 、Li x Fe 2 O 3 (0≤x≤1), Li x WO 2 (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 and Group 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) of a group.

[0126] Some examples of materials capable of doping and undoping lithium can include Si, SiO x (0 < x ≤ 2), Si-Y alloy (Y is selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and is not Si), Sn, SnO 2 、Sn-Y (Y is selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and is not Sn), and at least one of them can be mixed with SiO 2 As the element Y, one 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, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po and their combinations can be used.

[0127] Examples of transition metal oxides include lithium-containing titanium oxide (LTO), vanadium oxide, lithium vanadium oxide, etc.

[0128] Based on the total weight of the solids in the negative electrode paste, the content of the negative electrode active material can be 80% to 99% by weight.

[0129] The binder is a component that assists the bonding between the conductive material, the active material and the current collector, and is generally added in an amount of 1 to 30 weight percent based on the total weight of the solids in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, fluororubber and various copolymers thereof.

[0130] The conductive material is a component for further improving the conductivity of the negative electrode active material, and the addition amount may be 1 to 20 weight % based on the total weight of the solid in the negative electrode slurry. Such a conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride, aluminum, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives, etc.

[0131] The solvent may include water or an organic solvent, such as NMP or an alcohol, and may be used in an amount that becomes a desired viscosity when including the negative electrode active material and the optional binder and the conductive material. For example, the concentration of the solid in the slurry containing the negative electrode active material and the optional binder and the conductive material may be 30 wt % to 75 wt %, preferably 40 wt % to 65 wt %.

[0132] As the separator, an organic separator or an organic and inorganic composite separator may be used.

[0133] The porous polymer film prepared by polyolefin polymer (such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer) can be used alone, or its laminate can be used as organic separator. Alternatively, general porous nonwoven fabric (such as nonwoven fabric made of glass fiber, polyethylene terephthalate fiber, etc. with high melting point) can be used as organic separator.

[0134] As the organic and inorganic composite separator, an organic / inorganic composite porous safety reinforced separator (SRS) obtained by applying a porous coating layer containing inorganic particles and a binder polymer on a porous polyolefin-based separator substrate may be used.

[0135] Inorganic particles having lithium ion transfer capability or a mixture thereof are preferably used as the inorganic particles, and some examples of the inorganic particles include those selected from the group consisting of BaTiO 3 、BaTiO 3, Pb(Zr,Ti)O 3 (PZT), Pb 1-x La x Zr 1-y Ti y O 3 (PLZT, where 0 < x < 1, 0 < y < 1), hafnium dioxide (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , Al 2 O 3 , TiO 2 , SiC and mixtures of one or more of these mixtures.

[0136] The external shape of the lithium secondary battery of the present invention is not particularly limited, but the lithium secondary battery may have a cylindrical shape, a prismatic shape, a pouch shape, or a coin shape using a can.

[0137] Hereinafter, the present invention will be described in detail with reference to embodiments. However, the embodiments according to the present invention can 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 fully describe the present invention to those skilled in the art.

[0138] Example 1

[0139] (Preparation of non-aqueous electrolyte solution)

[0140] Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a volume ratio of 30:70, and LiPF 6 and LiFSI are dissolved therein to have a concentration of 1.0 M LiPF 6 , thereby manufacturing a non-aqueous organic solvent. The non-aqueous electrolyte solution of the present invention is manufactured by adding 0.3 wt% of the compound represented by Chemical Formula 1a, 0.5 wt% of the compound represented by Chemical Formula 2a, 1.0 wt% of vinylene carbonate (VC), and 0.5 wt% of propane sultone (PS) to the non-aqueous organic solvent (see Table 1 below).

[0141] (Electrode preparation)

[0142] By using a positive electrode active material (Li(Ni 0.85 Co 0.05 Mn 0.08 Al 0.02 )O2 ), a conductive material (carbon black) and a binder (polyvinylidene fluoride) were added to N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 98:0.7:1.3 to prepare a positive electrode active material slurry (solid concentration 74 wt%). The positive electrode was manufactured by applying the positive electrode active material slurry on a positive electrode collector (Al film) with a thickness of 15 μm, then drying the slurry and rolling the positive electrode collector.

[0143] The negative electrode active material slurry (solid concentration 52 wt%) was prepared by adding the negative electrode active material (artificial graphite), the binder (CMC) and the conductive material (carbon black) to distilled water as a solvent at a weight ratio of 95.5:3.5:1. The negative electrode was prepared by applying the negative electrode active material slurry on a negative electrode current collector (Cu film) having a thickness of 8 μm, then drying the slurry and rolling the negative electrode current collector.

[0144] (Preparation of Secondary Battery)

[0145] The positive electrode and negative electrode manufactured in the above manner were sequentially laminated with a polyethylene porous film to manufacture an electrode assembly. Thereafter, the electrode assembly was placed in a battery case, a non-aqueous electrolyte solution was injected into the battery case, and then the battery case was sealed to manufacture a lithium secondary battery (battery capacity 2Ah).

[0146] Examples 2 to 6

[0147] Non-aqueous electrolyte solutions were prepared by changing the amount of the first additive and the amount of the second additive in Example 1 and the types and amounts of other additives as shown in Table 1. In addition, electrodes and secondary batteries were prepared in the same manner as in Example 1.

[0148] Comparative Examples 1 to 3

[0149] Non-aqueous electrolyte solutions were prepared by changing the amount of the first additive and the amount of the second additive in Example 1 and the types and amounts of other additives as shown in Table 1. In addition, electrodes and secondary batteries were prepared in the same manner as in Example 1.

[0150] Experimental Example 1: Evaluation of capacity retention after high temperature (60°C) storage

[0151] The lithium secondary batteries manufactured in Examples 1 to 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 were formed under 200mA current (0.1C rate), and the formed batteries were stored at 60°C for one day, and then the gas in the battery was removed (degassing process). Thereafter, the batteries were charged at 0.33C / 4.2V constant current / constant voltage (CC / CV) and 4.2V / 0.05C at 25°C, and discharged at 0.33C / 2.5V constant current. At this point, the discharge capacity measured using a PNE-0506 charge-discharge device (manufacturer: PNE Solution Co., Ltd., 5V, 6A) was defined as the initial discharge capacity.

[0152] Thereafter, each secondary battery was set to a SOC 100% state of charge and then stored at 60° C. for 4 weeks.

[0153] Thereafter, charging was performed at 25°C under the conditions of 0.33C / 4.2V constant current / constant voltage (CC / CV) and 4.2V / 0.05C, and discharging was performed under the conditions of 0.33C / 2.5V constant current. In addition, the discharge capacity was measured using a PNE-0506 charge-discharge device (manufacturer: PNE Solution Co., Ltd., 5V, 6A). At this time, the measured capacity was defined as the discharge capacity after high temperature storage.

[0154] The measured initial discharge capacity and discharge capacity after high-temperature storage were applied to the following formula (1) to measure the capacity retention rate, and the results are shown in Table 1 below.

[0155] Formula (1): Capacity retention rate (%) = (discharge capacity after high temperature storage / initial discharge capacity) × 100

[0156] Experimental Example 2: Evaluation of resistance increase after high temperature (60%) storage

[0157] The lithium secondary batteries manufactured in Examples 1 to 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 were formed under a current of 200 mA (0.1 C rate), and then the gas in the battery was removed (degassing process). Thereafter, charging was performed at 0.33C / 4.2V constant current / constant voltage (CC / CV) and 4.2V / 0.05C at 25°C, and discharging was performed at a constant current of 0.33C / 2.5V to reach SOC 50%. Thereafter, the initial resistance value was obtained by measuring the voltage drop, which was shown in a state where a discharge pulse was provided for 10 seconds at a constant current of 2.5C using a PNE-0506 charge-discharge device (manufacturer: PNE Solution Co., Ltd., 5V, 6A). Thereafter, charging was performed under conditions of 0.33C / 4.25 constant current / constant voltage (CC / CV) and 4.2V / 0.05C at a voltage operating range of 2.5V to 4.2V, thereby charging the battery to a SOC 100% state.

[0158] Thereafter, each secondary battery was left alone at 60° C. for 4 weeks.

[0159] Thereafter, the battery was charged under the conditions of 0.33C / 4.2V constant current / constant voltage (CC / CV) and 4.2V / 0.05C, and discharged at 0.33C using a PNE-0506 charge-discharge device (manufacturer: PNE Solution Co., Ltd., 5V, 6A) to bring the battery to a SOC 50% state. Thereafter, the resistance value after high temperature storage was obtained by measuring the voltage drop, which was shown in the state of 2.5C constant current pulse discharge for 10 seconds.

[0160] The resistance increase rate (%) of each secondary battery was calculated from the ratio of the increased resistance after high-temperature storage relative to the initial resistance using the following formula (2), and the results are shown in Table 1 below.

[0161] Formula (2): Resistance increase rate (%) = {(resistance after high temperature storage - initial resistance) / initial resistance} × 100

[0162] Experimental Example 3: Evaluation of volume increase rate after high temperature (60%) storage

[0163] The lithium secondary batteries manufactured in Examples 1 to 6 and the lithium secondary batteries manufactured in Comparative Examples 1 to 3 were formed under a current of 200 mA (0.1 C rate), and then the gas in the battery was removed (degassing process). Thereafter, the battery was fully charged to SOC 100% at 0.33C / 4.2V constant current / constant voltage (CC / CV) and 4.2V / 0.05C at 25°C. In this state, the initial volume was obtained by placing the insulated lithium secondary battery in a bowl filled with distilled water at room temperature using TWD-150DM (manufacturer: Two-pls) and calculating using the Archimedes principle.

[0164] Thereafter, each secondary battery was left alone at 60° C. for 4 weeks.

[0165] After that, after cooling each lithium secondary battery at room temperature, the volume after high temperature storage was measured in the same manner as above, and the measured initial volume and the volume after high temperature storage were substituted into the following formula (3) to calculate the volume increase rate. Thereafter, the results are shown in Table 1.

[0166] Formula (3): Volume increase rate (%) = [{(volume after high temperature storage - initial volume) / initial volume)} × 100]

[0167] [Table 1]

[0168]

[0169] Referring to Table 1 above, the secondary batteries of Examples 1 to 5 show a more excellent capacity retention rate after high temperature storage compared to the secondary batteries of Comparative Examples 1 to 3. In addition, the resistance increase rate and volume increase rate after high temperature storage in the secondary batteries of Examples 1 to 5 are reduced compared to the secondary batteries of Comparative Examples 1 to 3. Therefore, it can be seen that the nonaqueous electrolyte solution containing the first additive and the second additive of the present invention shows the effect of improving the characteristics after high temperature storage.

[0170] In addition, the secondary battery of Example 6 in which no additional additive (VC, PS) was added had poor characteristics after high temperature storage compared to Examples 1 to 5 in which the additional additive was added. Therefore, it can be seen that in addition to the first additive and the second additive, it is preferred to include an additional additive in the non-aqueous electrolyte solution to improve the characteristics after high temperature storage.

[0171] The above description merely illustrates the technical idea of ​​the present invention, and a person skilled in the art to which the present invention belongs may make various modifications and changes without departing from the basic characteristics of the present invention. Therefore, the drawings disclosed in the present invention are not intended to limit the technical idea of ​​the present invention, but to describe the present invention, and the scope of the technical idea of ​​the present invention is not limited by these drawings. The scope of protection of the present invention shall be interpreted by the attached claims, and all technical ideas within their equivalent scope shall be interpreted as included within the scope of the present invention.

Claims

1. A non-aqueous electrolyte solution for a lithium secondary battery, the non-aqueous electrolyte solution comprising: Lithium salts; Organic solvents; First additive; A second additive, and Vinylene carbonate (VC) and propane sultone (PS) as additives, in, The first additive is a compound represented by the following Chemical Formula 1: [Chemical formula 1] Among them, R 1 To R 3 are each hydrogen or an alkyl group having 1 to 3 carbon atoms, Wherein, the second additive is a compound represented by the following chemical formula 2: [Chemical formula 2] and Here, L is an alkylene group having 1 to 10 carbon atoms.

2. The non-aqueous electrolyte solution according to claim 1, in, The electrolyte solution contains the first additive in an amount corresponding to 0.05 wt % to 3 wt % of the total weight of the electrolyte solution, and The amount of the second additive contained in the electrolyte solution corresponds to 0.05 wt % to 5 wt % of the total weight of the electrolyte solution.

3. The non-aqueous electrolyte solution according to claim 1, in, The first additive and the second additive are each contained in the electrolyte solution in an amount corresponding to 0.3 wt % to 3 wt % of the total weight of the electrolyte solution.

4. The nonaqueous electrolyte solution according to claim 1, in, The weight ratio of the first additive to the second additive is 2:8 to 7:

3.

5. The non-aqueous electrolyte solution according to claim 1, in, The weight ratio of the first additive to the second additive is 3:7 to 6:

4.

6. The non-aqueous electrolyte solution according to claim 1, in, The compound represented by Chemical Formula 1 is a compound represented by the following Chemical Formula 1a: [Chemical formula 1a] 7. The nonaqueous electrolyte solution according to claim 1, in, The compound represented by Chemical Formula 2 is a compound represented by the following Chemical Formula 2a: [Chemical formula 2a] 8. The non-aqueous electrolyte solution according to claim 1, further comprising: at least one selected from the group consisting of halogen-substituted or unsubstituted cyclic carbonate compounds, propionate compounds, nitrile compounds, phosphate compounds, borate compounds, sultone compounds, sulfate compounds and lithium salt compounds.

9. The nonaqueous electrolyte solution according to claim 1, in, A weight ratio of the total weight of the first additive and the second additive to the total weight of the vinylene carbonate (VC) and the propane sultone (PS) is 1:1 to 1:

4.

10. The non-aqueous electrolyte solution according to claim 1, in, A weight ratio of the total weight of the first additive and the second additive to the total weight of the vinylene carbonate (VC) and the propane sultone (PS) is 1:1 to 1:

3.

11. The nonaqueous electrolyte solution according to claim 1, in, The lithium salt contains LiPF 6 . 12 . A lithium secondary battery comprising the non-aqueous electrolyte solution for a lithium secondary battery according to claim 1 .

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