Nonaqueous electrolyte and lithium secondary battery containing same

Abstract

The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a compound represented by the following Chemical Formula 1 as an additive. JPEG2025539657000072.jpg48170In the above Chemical Formula 1, n is an integer of 0 or 1; R1 is any one selected from the group consisting of R, an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, OR', OCOR', F, and CH2PO(R)2; and R' may be any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and PO(R)2. In the above Chemical Formula 1 and R1, R is a structure represented by the following Chemical Formula 2. JPEG2025539657000073.jpg58170In the above chemical formula 2, Rx and Ry are each independently either H or F.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0117304 filed on September 4, 2023, and Korean Patent Application No. 10-2024-0119601 filed on September 3, 2024, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

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

[0003] In recent years, the application areas of lithium secondary batteries have rapidly expanded from power supply for electronic devices such as electrical, electronic, communication, and computer equipment to power storage and supply for large-area devices such as automobiles and power storage devices. Accordingly, there has been an increasing demand for high-capacity, high-power, and highly stable secondary batteries.

[0004] In particular, high capacity, high power output, and long life are important characteristics for lithium secondary batteries for automotive applications. To achieve high capacity, secondary batteries may use positive electrode active materials with high nickel content, which have high energy density but low stability, or may be operated at high voltage.

[0005] However, when a secondary battery is operated under the above conditions, as charging and discharging proceeds, the coating formed on the surface of the positive and negative electrodes or the electrode surface structure deteriorates due to side reactions caused by electrolyte degradation, which can lead to the elution of transition metal ions from the surface of the positive electrode.The eluted transition metal ions are then electro-deposited on the negative electrode, reducing the passivation ability of the SEI, resulting in the degradation of the negative electrode.

[0006] Such deterioration of secondary batteries tends to be accelerated when the potential of the positive electrode is increased, or when the battery is exposed to heat generated during operation or to an external high-temperature environment.

[0007] Furthermore, when a lithium secondary battery is used continuously for a long time or left at a high temperature, gas is generated and the thickness of the battery increases, which is called swelling. It is known that the amount of gas generated at this time depends on the state of the SEI.

[0008] Therefore, in order to solve these problems, research and development efforts are being conducted to find methods that can suppress the elution of metal ions from the positive electrode, form a stable SEI film on the negative electrode, reduce the swelling phenomenon of secondary batteries, and improve their long-term life characteristics and high-temperature durability. Summary of the Invention [Problem to be solved by the invention]

[0009] As a result of extensive research into solving the above problems, an object of the present invention is to provide an additive for a non-aqueous electrolyte that can suppress deterioration of a positive electrode, reduce side reactions between a positive electrode and an electrolyte, and form a stable SEI film on a negative electrode.

[0010] Another object of the present invention is to provide a non-aqueous electrolyte that contains the additive for a non-aqueous electrolyte and thereby has improved stability at high temperatures.

[0011] Another object of the present invention is to provide a lithium secondary battery containing the non-aqueous electrolyte, which has improved high-temperature cycle characteristics and high-temperature storage characteristics, and thus improved performance. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides a non-aqueous electrolyte containing a lithium salt, an organic solvent, and a compound represented by the following Chemical Formula 1 as an additive:

[0013] [ka]

[0014] In the above Chemical Formula 1, n is an integer of 0 or 1; R1 is any one selected from the group consisting of R, an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, OR', OCOR', F, and CH2PO(R)2; R' is any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and PO(R)2; and R has a structure represented by the following Chemical Formula 2.

[0015] [ka]

[0016] In the above formula 2, Rx and Ry are each independently either H or F.

[0017] The present invention also provides a lithium secondary battery containing the non-aqueous electrolyte. [Effects of the Invention]

[0018] The compound represented by Chemical Formula 1, which is provided as an additive for non-aqueous electrolytes according to the present invention, overcomes the problems associated with 1,3-propane sultone, a widely used electrolyte additive for film formation. 1,3-propane sultone increases the resistance of lithium secondary batteries, making it difficult to add large amounts to the electrolyte and generating toxic by-products. Therefore, 1,3-propane sultone degrades the output characteristics of lithium secondary batteries, and its limited addition in large amounts makes it difficult to achieve sufficiently long battery life.

[0019] The compound represented by Chemical Formula 1, which is provided as an additive for a non-aqueous electrolyte according to the present invention, contains two or more R structures derived from 1,3-propane sultone in the molecule, and thus can form a large amount of strong coating on the positive / negative electrodes without using an excessive amount, thereby providing a lithium secondary battery having excellent high-voltage life characteristics, high-temperature life characteristics, high-temperature durability, etc.

[0020] In addition, the compound of Chemical Formula 1 has a P-containing linker linked to the carbon at position 3, which is responsible for the toxicity-inducing reaction of 1,3-propane sultone, thereby reducing the generation of toxic by-products. Furthermore, in the compound of Chemical Formula 1, the unique properties of electron-rich phosphorus (P) improve lithium ion transport properties when the P-containing linker forms a coating on the positive and negative electrodes. This allows the compound of Chemical Formula 1 to form stable CEI (Cathode Electrolyte Interface) and SEI (Solid Electrolyte Interphase) coatings on the surfaces of the positive and negative electrodes. This prevents the degradation of the positive electrode active material and the elution of transition metals at high voltages, and also prevents the deterioration of the SEI passivation ability at high temperatures, preventing the degradation of the negative electrode.

[0021] Therefore, by using the nonaqueous electrolyte of the present invention containing the compound of Chemical Formula 1 as an additive, an electrode-electrolyte interface that is stable and has low resistance even at high temperatures can be formed, thereby improving the high-temperature cycle characteristics and high-temperature storage characteristics, and realizing a lithium secondary battery with improved performance. DETAILED DESCRIPTION OF THE INVENTION

[0022] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0023] As used herein, the terms "comprises," "comprises," or "having" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the presence or possible addition of one or more other features, numbers, steps, components, or combinations thereof.

[0024] Meanwhile, before describing the present invention, unless otherwise specified in the present invention, "*" means a linking moiety between the same or different atoms or terminal ends of a chemical formula.

[0025] In addition, in the description of "number of carbon atoms a to b" herein, "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. For example, "an alkyl group having 1 to 5 carbon atoms" refers to an alkyl group containing 1 to 5 carbon atoms, i.e., -CH3, -CH2CH3, -CH2CH2CH3, -CH2C(CH3)H2, -CH(CH3)2, -CH(CH3)CH2CH3, -CH(CH2CH3)2, etc.

[0026] In addition, in this specification, the alkyl group, alkenyl group, and alkynyl group may be substituted or unsubstituted. Unless otherwise defined, the term "substituted" means that at least one hydrogen atom bonded to a carbon atom is replaced with an element other than hydrogen, for example, a halogen atom such as F or Cl.

[0027] The present invention will be described in detail below.

[0028] The non-aqueous electrolyte and / or lithium secondary battery according to the present invention includes at least one of the configurations disclosed below, and may include any technically possible combination of the following configurations.

[0029] non-aqueous electrolyte The non-aqueous electrolyte of the present invention contains a lithium salt, an organic solvent, and a non-aqueous electrolyte additive represented by the following chemical formula 1.

[0030] [ka]

[0031] In the above Chemical Formula 1, n is an integer of 0 or 1.

[0032] In Chemical Formula 1, R1 is any one selected from the group consisting of R, an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, OR', OCOR', F, and CH2PO(R)2, and R' is any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and PO(R)2.

[0033] In the above Chemical Formula 1 and R1, R is a structure represented by the following Chemical Formula 2.

[0034] [ka]

[0035] In the above formula 2, Rx and Ry are each independently either H or F.

[0036] The compound of Chemical Formula 1 contains two or more R structures derived from 1,3-propane sultone in the molecule, and thus can form a large amount of strong coating on the positive / negative electrodes without using an excessive amount, thereby providing a lithium secondary battery with excellent high-voltage life characteristics, high-temperature life characteristics, high-temperature durability, etc.

[0037] In addition, the compound of Chemical Formula 1 has a P-containing linker linked to the carbon at position 3, which is responsible for the toxicity-inducing reaction of 1,3-propane sultone, thereby reducing the generation of toxic by-products. Furthermore, in the compound of Chemical Formula 1, the unique properties of electron-rich phosphorus (P) improve lithium ion transport properties when the P-containing linker forms a coating on the positive and negative electrodes. This allows the compound of Chemical Formula 1 to form stable CEI (Cathode Electrolyte Interface) and SEI (Solid Electrolyte Interphase) coatings on the surfaces of the positive and negative electrodes. Therefore, it can prevent chain structural collapse due to oxygen desorption from the positive electrode at high temperatures, as well as reduce the deterioration of the SEI's passivation ability, preventing negative electrode degradation.

[0038] Therefore, by using the nonaqueous electrolyte of the present invention containing the compound of Chemical Formula 1, an electrode-electrolyte interface that is stable even at high temperatures and has low resistance can be formed, thereby improving high-temperature cycle characteristics and high-temperature storage characteristics, and realizing a lithium secondary battery with improved performance.

[0039] The compound of Chemical Formula 1 may be a compound represented by the following Chemical Formula 1-1.

[0040] [ka]

[0041] In Chemical Formula 1-1, R1 is F, R, or OR', and R' may be any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine.

[0042] In the above chemical formula 1-1 and R1, R may be a structure represented by the following chemical formula 2.

[0043] [ka]

[0044] In the above formula 2, Rx and Ry may each independently be either H or F.

[0045] Specifically, the compound represented by Chemical Formula 1-1 may be any one of the compounds represented by Chemical Formulas 1-1a to 1-1f below.

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] In the chemical formulas 1-1a to 1-1f, R may be a structure represented by the following chemical formula 2-1.

[0053] [ka]

[0054] The compound of Chemical Formula 1 may be a compound represented by the following Chemical Formula 1-2.

[0055] [ka]

[0056] In the above formula 1-2, X may be —CH 2 — or —O—.

[0057] In the above chemical formula 1-2 and R1, R may be a structure represented by the following chemical formula 2.

[0058] [ka]

[0059] In the above formula 2, Rx and Ry may each independently be either H or F.

[0060] Specifically, the compound represented by Chemical Formula 1-2 may be any one of compounds represented by Chemical Formulas 1-2a and 1-2b below.

[0061] [ka]

[0062] [ka]

[0063] In the chemical formulas 1-2a and 1-2b, R may be a structure represented by the following chemical formula 2-1.

[0064] [ka]

[0065] The compound of Formula 1 may be a compound represented by the following Formula 1-3.

[0066] [ka]

[0067] In Chemical Formula 1-3, R1 is F, R, or OR', and R' may be any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine.

[0068] In the above chemical formulas 1-3 and R1, R may be a structure represented by the following chemical formula 2.

[0069] [ka]

[0070] In the above formula 2, Rx and Ry may each independently be either H or F.

[0071] Specifically, the compound represented by Chemical Formula 1-3 may be any one of the compounds represented by Chemical Formulas 1-3a to 1-3f below.

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] In the chemical formulas 1-3a to 1-3f, R may be a structure represented by the following chemical formula 2-1.

[0079] [ka]

[0080] The additive for a non-aqueous electrolyte according to the present invention may be contained in an amount of 0.1 to 5 parts by weight, preferably 0.1 to 3 parts by weight, and more preferably 0.1 to 1 part by weight, per 100 parts by weight of the non-aqueous electrolyte. When the content of the compound represented by Chemical Formula 1 satisfies the above range, the effect of forming a coating on the positive electrode and negative electrode is sufficient, the elution of transition metals from the positive electrode active material is suppressed, and the deterioration of the negative electrode is also suppressed. Furthermore, the lithium mobility in the electrolyte is appropriate, and the resistance of the lithium secondary battery is low.

[0081] The lithium salt contained in the non-aqueous electrolyte of the present invention is used as an electrolyte salt in a lithium secondary battery and is used as a medium for transferring ions. + and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 -, PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - , and SCN - At least one selected from the group consisting of:

[0082] Specifically, the lithium salts include LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide; LiBETI), and LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide; LiTFSI). In addition to these, any lithium salt commonly used in the electrolyte of a lithium secondary battery can be used without any limitation.

[0083] The lithium salt can be varied as appropriate within a range that is normally usable, but to obtain the optimum effect of forming a corrosion-preventing coating on the electrode surface, it may be contained in the electrolyte at a concentration of 0.5 M to 4.0 M, preferably 0.5 M to 3.0 M, and more preferably 0.8 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics of the lithium secondary battery during high-temperature storage is sufficient, and the viscosity of the non-aqueous electrolyte is appropriate, resulting in improved electrolyte impregnation.

[0084] The organic solvent may include at least one organic solvent selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0085] Specifically, the organic solvent may include a cyclic carbonate organic solvent, a linear carbonate organic solvent, or a mixed organic solvent thereof.

[0086] The cyclic carbonate organic solvent is a highly viscous organic solvent that has a high dielectric constant and therefore easily dissociates the lithium salt in the electrolyte. Specific examples of the cyclic carbonate organic solvent 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, ethylene carbonate may be included.

[0087] The linear carbonate organic solvent is an organic solvent having low viscosity and low dielectric constant, and typical examples thereof include 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, ethyl methyl carbonate (EMC) may be used.

[0088] In addition, in order to produce an electrolyte having high ionic conductivity, the organic solvent may further include at least one ester organic solvent selected from the group consisting of linear ester organic solvents and cyclic ester organic solvents in addition to the at least one carbonate organic solvent selected from the group consisting of cyclic carbonate organic solvents and linear carbonate organic solvents.

[0089] Specific examples of such linear ester-based organic solvents include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0090] The cyclic ester organic solvent may be at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0091] Meanwhile, the organic solvent may further include, as needed, any organic solvent commonly used in non-aqueous electrolytes, for example, at least one of an ether-based organic solvent, a glyme-based organic solvent, and a nitrile-based organic solvent.

[0092] The ether solvent may be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more thereof, but is not limited thereto.

[0093] The glyme-based solvent has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents and is less reactive with metals, and may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME), but is not limited thereto.

[0094] The nitrile solvent may be one or more 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, but is not limited thereto.

[0095] In addition, the non-aqueous electrolyte of the present invention may further contain a known electrolyte additive, as needed, to prevent the non-aqueous electrolyte from being decomposed and causing the collapse of the negative electrode in a high-power environment, 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.

[0096] Representative examples of such other electrolyte additives may include at least one additive for forming an SEI film selected from the group consisting of cyclic carbonate-based compounds, halogen-substituted carbonate-based compounds, sultone-based compounds, sulfate-based compounds, phosphate-based compounds, borate-based compounds, nitrile-based compounds, benzene-based compounds, amine-based compounds, silane-based compounds, and lithium salt-based compounds.

[0097] Examples of the cyclic carbonate compounds include vinylene carbonate (VC) and vinylethylene carbonate.

[0098] The halogen-substituted carbonate compounds include fluoroethylene carbonate (FEC).

[0099] The sultone compound may be 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.

[0100] Examples of the sulfate-based compounds include ethylene sulfate (Esa), trimethylene sulfate (TMS), and methyl trimethylene sulfate (MTMS).

[0101] The phosphate-based compound may be 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(2,2,2-trifluoroethyl)phosphite.

[0102] The borate-based compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalateborate (LiB(C2O4)2, LiBOB).

[0103] The nitrile compound may be at least one compound selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0104] The benzene-based compound may be fluorobenzene, the amine-based compound may be triethanolamine or ethylenediamine, and the silane-based compound may be tetravinylsilane.

[0105] The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and examples thereof include lithium difluorophosphate (LiDFP), LiPO2F2, and LiBF4.

[0106] Among these other electrolyte additives, when a combination of vinylene carbonate (VC), 1,3-propane sultone (PS), and ethylene sulfate (Esa) is included, a stronger SEI coating can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, the generation of gas that may be generated by decomposition of the electrolyte at high temperatures can be suppressed, and the high-temperature stability of the secondary battery can be improved.

[0107] Meanwhile, the other electrolyte additives may be used in combination of two or more kinds, and may be included in an amount of 0.1 wt % to 10 wt %, specifically 0.2 wt % to 8 wt %, and preferably 0.5 wt % to 8 wt %, based on the total weight of the non-aqueous electrolyte. When the content of the other electrolyte additives satisfies the above range, better ionic conductivity and improved cycle characteristics can be obtained.

[0108] Lithium secondary battery The present invention also provides a lithium secondary battery containing the non-aqueous electrolyte.

[0109] Specifically, the lithium secondary battery includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte.

[0110] The lithium secondary battery of the present invention can be manufactured by a conventional method known in the art, for example, by forming an electrode assembly in which a positive electrode, a negative electrode, and a separator between the positive electrode and the negative electrode are sequentially stacked, inserting the electrode assembly into a battery case, and injecting the nonaqueous electrolyte according to the present invention into the battery case.

[0111] (1) Positive electrode The positive electrode may be prepared by coating a positive electrode mixture slurry containing a positive electrode active material, a binder, a conductive material, and a solvent on a positive electrode current collector.

[0112] 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 treated with carbon, nickel, titanium, silver, or the like may be used.

[0113] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium metal oxide is a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), 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 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Co q Mn r [[ID=二十六]])O2 (where 0 < p < 1, 0 < q < 1, 0 < r < 1, p + q + r = 1) or Li(Ni p1 Co q1 Mn r1 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r1 < 2, p1 + q1 + r1 = 2), etc.), or a lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2)O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r2, and s2 are atomic fractions of independent elements, respectively, where 0 < p2 < 1, 0 < q2 < 1, 0 < r2 < 1, 0 < s2 < 1, and p2 + q2 + r2 + s2 = 1), etc.) etc. may be mentioned, and any one or two or more of these compounds may be included.

[0114] Among them, from the point of view of being able to enhance the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (for example, 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, etc.), lithium nickel cobalt aluminum oxide (for example, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), or lithium nickel manganese cobalt aluminum oxide (for example, Li(Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 )O2), etc. may be used, and any one or two or more of these mixtures may be used.

[0115] Among them, from the point of view of being able to maximize the capacity characteristics of the battery, a positive electrode active material with a nickel content of 80 atm% or more may be used. For example, the lithium transition metal oxide may include those represented by the following Chemical Formula 3.

[0116] [Chemical Formula 3] Li x Nia Co b M 1 c M 2 d O2

[0117] In the above Chemical Formula 3, the M 1 is one or more selected from Mn and Al, and may be preferably Mn or a combination of Mn and Al.

[0118] M 2 may be one or more selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S.

[0119] The x represents the atomic fraction of lithium in the lithium transition metal oxide, and may be 0.90≦x≦1.1, preferably 0.95≦x≦1.08, and more preferably 1.0≦x≦1.08.

[0120] The a represents the atomic fraction of nickel among the metal elements excluding lithium in the lithium transition metal oxide, and may be 0.80≦a<1.0, preferably 0.80≦a≦0.95, and more preferably 0.80≦a≦0.90. When the nickel content satisfies the above range, high capacity characteristics can be achieved.

[0121] The b represents the atomic fraction of cobalt among the metal elements excluding lithium in the lithium transition metal oxide, and is 0. <b<0.2、0<b≦0.15、または0.01≦b≦0.10であってよい。

[0122] The c is M among the metal elements other than lithium in the lithium transition metal oxide. 1 represents the atomic fraction of 0 <c<0.2、0<c≦0.15、または0.01≦c≦0.10であってよい。

[0123] The d is the number of metal elements other than lithium in the lithium transition metal oxide. 2 and may be 0≦d≦0.1, or 0≦d≦0.05.

[0124] The positive electrode active material may be contained in an amount of 60% to 99% by weight, preferably 70% to 99% by weight, and more preferably 80% to 98% by weight, based on the total weight of solids in the positive electrode mixture slurry excluding the solvent.

[0125] The binder is a component that assists in binding the active material and the conductive material, etc., and in binding the active material to the current collector.

[0126] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers.

[0127] Typically, the binder may be contained in an amount of 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 1 to 10% by weight, based on the total weight of the solid content excluding the solvent in the positive electrode mixture slurry.

[0128] The conductive material is a component for further improving the conductivity of the positive electrode active material, and may be added in an amount of 1 wt % to 20 wt % based on the total weight of the solid content in the positive electrode mixture slurry. Such a conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity, and examples thereof 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.

[0129] Typically, the conductive material may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids in the positive electrode mixture slurry excluding the solvent.

[0130] The solvent may include 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, are contained. For example, the solvent may be contained so that the concentration of the solids including the positive electrode active material, and optionally a binder and a conductive material, is 50% by weight to 95% by weight, preferably 70% by weight to 95% by weight, and more preferably 70% by weight to 90% by weight.

[0131] (2) Negative electrode The negative electrode may be prepared by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, or a graphite electrode made of carbon (C) or a metal itself may be used as the negative electrode.

[0132] For example, when a negative electrode is manufactured by coating a negative electrode mixture slurry onto the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloy, etc. may be used. Furthermore, as with the positive electrode current collector, the bonding strength of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and the negative electrode current collector may be used in various forms such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0133] In addition, 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 or an alloy of such a metal and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0134] The carbonaceous material capable of reversibly intercalating / deintercalating lithium ions may be any carbonaceous negative electrode active material commonly used in lithium ion secondary batteries, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination of these. Examples of crystalline carbon include graphite, such as amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite. Examples of amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, and calcined coke.

[0135] 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.

[0136] As the metal composite oxide, 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) selected from the group consisting of can be used.

[0137] As the substance capable of doping and undoping lithium, 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 a combination 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 a combination thereof, and is not Sn), etc. can be mentioned, and at least one of these and SiO2 may be mixed 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 a combination thereof.

[0138] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, and the like.

[0139] Among them, the negative electrode active material may be a mixture of graphite and SiO x (0 < x ≤ 2). From the viewpoint of increasing the capacity of the lithium secondary battery, the graphite and SiO x (0 < x ≤ 2) may be contained in a weight ratio of 99.5:0.5 to 70:30.

[0140] The negative electrode active material may be contained in an amount of 60% to 99% by weight, preferably 70% to 99% by weight, more preferably 80% to 98% by weight, based on the total weight of the solid content in the negative electrode binder slurry.

[0141] The binder is a component that aids in binding between the conductive material, the active material, and the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluorine rubber, and various copolymers thereof.

[0142] Generally, the binder may be contained in an amount of 1% to 20% by weight, preferably 1% to 15% by weight, more preferably 1% to 10% by weight, based on the total weight of the solid matter excluding the solvent in the negative electrode binder slurry.

[0143] 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 wt % to 20 wt % based on the total weight of the solid content in the negative electrode mixture slurry. Such a conductive material is not particularly limited as long as it does not cause chemical changes in the battery and has conductivity, and examples thereof 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 crystalline 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.

[0144] The conductive material may be contained in an amount of 1 to 20% by weight, preferably 1 to 15% by weight, and more preferably 1 to 10% by weight, based on the total weight of solids in the negative electrode mixture slurry excluding the solvent.

[0145] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), 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. For example, the solvent may be contained so that the concentration of the solids including the negative electrode active material, and optionally a binder and a conductive material, is 50% by weight to 95% by weight, preferably 70% by weight to 90% by weight.

[0146] When a metal is used as the anode, the anode can be manufactured by physically bonding, rolling, or depositing a metal on a metal thin film or the anode current collector. The deposition method can be electrochemical deposition or chemical vapor deposition of the metal.

[0147] For example, the metal thin film itself or the metal bonded / rolled / deposited on the negative electrode current collector may include one metal or an alloy of two metals selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In).

[0148] (3) Separator The separator may be a conventional porous polymer film, such as 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, either alone or in a laminate, or a conventional porous nonwoven fabric, such as a nonwoven fabric made of a high-melting point glass fiber or polyethylene terephthalate fiber, but is not limited to these. Furthermore, to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material may be used, and may be selectively used as a single-layer or multi-layer structure.

[0149] 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.

[0150] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the present description and technical concept, and it goes without saying that such changes and modifications fall within the scope of the appended claims.

[0151] Example Example 1 (Production of non-aqueous electrolyte) LiPF was dissolved in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) = 20:70:10 volume ratio) to a concentration of 1.2 M to prepare a non-aqueous solvent, and 0.5 g of a compound represented by the following formula 1-1a was added to 99.5 g of the non-aqueous solvent to prepare a non-aqueous electrolyte.

[0152] [ka]

[0153] The R is a structure represented by the following chemical formula 2-1.

[0154] [ka]

[0155] (Lithium secondary battery manufacturing) Cathode active material (LiNi 0.60 Co 0.10 Mn 0.30 A cathode slurry (solid content 60 wt%) was prepared by adding O2, a conductive material (carbon black), and a binder (polyvinylidene fluoride) in a weight ratio of 97.6:0.8:1.6 to a solvent, N-methyl-2-pyrrolidone (NMP). The cathode slurry was applied to one side of a 13.5 μm-thick cathode current collector (Al thin film), dried, and roll-pressed to prepare a cathode.

[0156] Anode active material (graphite:SiO = 97.5:2.5 weight ratio), conductive material (carbon black), and binder (SBR-CMC) were mixed in a weight ratio of 95.6:1.0:3.4 to N-methyl-2-pyrrolidone (NMP) as a solvent to prepare anode slurry (solid content 60 wt%). The anode slurry was applied to one side of a 6 μm-thick anode current collector (Cu thin film), dried, and roll-pressed to prepare anode.

[0157] A porous polymer separator was interposed between the positive electrode and negative electrode prepared above in a dry room, and the non-aqueous electrolyte prepared above was injected to prepare a secondary battery.

[0158] Example 2 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following Formula 1-1b was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0159] [ka]

[0160] The R is a structure represented by the following chemical formula 2-1.

[0161] [ka]

[0162] Example 3 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following Formula 1-2a was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0163] [ka]

[0164] The R is a structure represented by the following chemical formula 2-1.

[0165] [ka] )

[0166] Example 4 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following Formula 1-1b was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0167] [ka]

[0168] The R is a structure represented by the following chemical formula 2-1.

[0169] [ka]

[0170] Example 5 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following Formula 1-3a was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0171] [ka]

[0172] The R is a structure represented by the following chemical formula 2-1.

[0173] [ka]

[0174] Example 6 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following Formula 1-3b was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0175] [ka]

[0176] The R is a structure represented by the following chemical formula 2-1.

[0177] [ka]

[0178] Example 7 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound represented by the following formula 1-3f was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0179] [ka]

[0180] The R is a structure represented by the following chemical formula 2-1.

[0181] [ka]

[0182] Comparative Example 1 A secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte was prepared using 100 g of the non-aqueous solvent prepared in Example 1.

[0183] Comparative Example 2 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of 1,3-propane sultone was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0184] Comparative Example 3 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound of the following formula A was added to 99.5 g of the nonaqueous solvent prepared in Example 1 to prepare a nonaqueous electrolyte.

[0185] [ka]

[0186] The R' is a structure represented by the following chemical formula B.

[0187] [ka]

[0188] Experimental Example 1 - Evaluation of high temperature cycle characteristics (1) The lithium secondary batteries manufactured in Examples 1 to 7 and the secondary batteries manufactured in Comparative Examples 1 to 3 were each subjected to a formation process at 25° C. and a rate of 0.1 C for 3 hours, and then charged at 25° C. and a rate of 0.33 C under CC-CV (constant current-constant voltage) conditions up to 4.4 V, and then discharged at a rate of 0.33 C under CC conditions down to 2.5 V. This charge-discharge cycle was counted as one cycle, and three cycles of initial charge-discharge were performed.

[0189] Next, at a high temperature (45°C), each of the initially charged and discharged lithium secondary batteries was charged under CC-CV conditions at a rate of 0.33 C to 4.4 V, and then discharged under CC conditions at a rate of 0.33 C to 2.5 V. This charge and discharge constituted one cycle, and 100 cycles were performed.

[0190] The capacity retention rate was calculated by substituting the capacity after the first cycle and the capacity after the 100th cycle into the following formula 1. The results are shown in Table 1 below.

[0191] [Formula 1] Capacity retention rate (%) = (discharge capacity after 100th cycle / discharge capacity after 1st cycle) x 100

[0192] Experimental Example 2 - Evaluation of high temperature cycle characteristics (2) The lithium secondary batteries manufactured in Examples 1 to 7 and the secondary batteries manufactured in Comparative Examples 1 to 3 were each charged at 25°C at a rate of 0.33 C to 4.4 V under CC-CV (constant current-constant voltage) conditions, and then discharged at a rate of 0.33 C to 2.5 V under CC conditions. This charge-discharge cycle was counted as one cycle, and three cycles of initial charge-discharge were performed. The SOC (State of Charge) was adjusted to 50% based on the discharge capacity of the third charge-discharge cycle. At a SOC (State of Charge) of 50%, a discharge pulse was applied at 2.5 C for 10 seconds, and the DC internal resistance was calculated from the voltage drop that occurred, and this resistance was set as the initial resistance.

[0193] Then, at a high temperature (45°C), each of the initially charged and discharged lithium secondary batteries was charged under CC-CV conditions at a rate of 0.33C to 4.4V, and then discharged under CC conditions at a rate of 0.33C to 2.5V. This charge-discharge cycle was counted as one cycle, and after 100 cycles, each lithium secondary battery was transferred to a charger / discharger at room temperature (25°C) and given a discharge pulse at 2.5C for 10 seconds at a State of Charge (SOC) of 50%, and the DC internal resistance was calculated from the voltage drop that occurred when the battery was charged.

[0194] The initial resistance and the resistance after the 100th cycle were substituted into the following formula 2 to calculate the high-temperature cycle resistance increase rate. The results are shown in Table 2 below.

[0195] [Formula 2] Resistance increase rate (%) = {(resistance after 100th cycle - initial resistance) / initial resistance} x 100

[0196] [Table 1]

[0197] As shown in Table 1, Examples 1 to 7, which used the additive for non-aqueous electrolytes of the present invention, showed improvements in both capacity retention and resistance increase rate compared to Comparative Examples 1 to 3, which did not use the additive. The lithium secondary batteries of Examples 1 to 7, which used the additive of the present invention in which a linker was attached to the third carbon of propane sultone, had a longer overall additive length compared to the lithium secondary battery of Comparative Example 3, which used the additive of Comparative Example 3 in which a linker was attached to the fourth carbon of propane sultone. Therefore, it is believed that the additive of the present invention increases the area covered by the coating, resulting in excellent high-temperature life characteristics.

[0198] Experimental Example 3 - Evaluation of high temperature storage characteristics (1) The lithium secondary batteries manufactured in Examples 1 to 7 and the secondary batteries manufactured in Comparative Examples 1 to 3 were charged at 25°C under CC-CV (constant current-constant voltage) conditions at a rate of 0.33C to 4.4V, and then discharged under CC conditions at a rate of 0.33C to 2.5V. This charge-discharge cycle was counted as one cycle, and three cycles of initial charge-discharge were performed. The discharge capacity of the third charge-discharge cycle was set as the initial discharge capacity. The batteries were then charged at a rate of 0.33C to 4.4V under CC-CV (constant current-constant voltage) conditions, and stored at 60°C for five weeks.

[0199] Then, each lithium secondary battery was transferred to a charger / discharger at room temperature (25°C) and charged under CC-CV conditions at a rate of 0.33 C to 4.4 V, and discharged under CC conditions at a rate of 0.33 C to 2.5 V. The high-temperature storage capacity retention rate was calculated by substituting the discharge capacity and initial capacity of the third charge / discharge into Equation 3 below. The results are shown in Table 2 below.

[0200] [Formula 3] Capacity retention rate (%) = (discharge capacity after 5 weeks of high temperature storage / initial discharge capacity) x 100

[0201] Experimental Example 4 - Evaluation of high temperature storage characteristics (2) The lithium secondary batteries manufactured in Examples 1 to 7 and the secondary batteries manufactured in Comparative Examples 1 to 3 were each charged at 25°C under CC-CV (constant current-constant voltage) conditions at a rate of 0.33C to 4.4V, and then discharged at a rate of 0.33C to 2.5V under CC conditions. This charge-discharge cycle constitutes one cycle, and three initial charge-discharge cycles were performed. The SOC (State of Charge) was adjusted to 50% based on the discharge capacity of the third charge-discharge cycle. At a SOC of 50%, a discharge pulse was applied at 2.5C for 10 seconds. The DC internal resistance was calculated from the voltage drop, and this resistance was set as the initial resistance. The batteries were then charged at a rate of 0.33C to 4.4V under CC-CV (constant current-constant voltage) conditions, and stored at 60°C for 5 weeks.

[0202] Then, each of the lithium secondary batteries was placed in a charger / discharger at room temperature (25°C), and a discharge pulse was applied at 2.5C for 10 seconds at a SOC (State of Charge) of 50%. The DC internal resistance was calculated from the voltage drop that occurred when the battery was charged.

[0203] The initial resistance and the high-temperature storage resistance were substituted into the following formula 4 to calculate the high-temperature storage resistance increase rate. The results are shown in Table 2 below.

[0204] [Formula 4] Resistance increase rate (%) = {(resistance after 5 weeks of high temperature storage - initial resistance) / initial resistance} x 100

[0205] Experimental Example 5 - Evaluation of high temperature storage characteristics (3) The lithium secondary batteries manufactured in Examples 1 to 7 and the secondary batteries manufactured in Comparative Examples 1 to 3 were each charged at 25°C at a rate of 0.33C up to 4.4V under CC-CV (constant current-constant voltage) conditions, and their volumes were measured at room temperature using a buoyancy method. This was designated as the initial volume (0%). The batteries after volume measurement were stored at 60°C for 5 weeks and then transferred to a charger / discharger at room temperature (25°C). The capacity retention rate of Experimental Example 3 was measured, and then the batteries were fully charged at 25°C at a rate of 0.33C up to 4.4V under CC-CV (constant current-constant voltage) conditions, and their volumes were measured using a buoyancy method. The initial volume and the high-temperature storage volume were substituted into the following equation 5 to calculate the high-temperature storage volume increase rate. The results are shown in Table 2 below.

[0206] [Formula 5] Volume increase rate (%) = {(volume after 5 weeks of high temperature storage - initial volume) / initial volume} x 100

[0207] [Table 2]

[0208] As shown in Table 2, the secondary batteries of Examples 1 to 7 were improved in the capacity retention rate, resistance increase rate, and volume increase rate after 5 weeks compared to the secondary batteries of Comparative Examples 1 to 3. The lithium secondary batteries of Examples 1 to 7, which used the additive of the present invention in which a linker was connected to the third carbon of propane sultone, had a longer overall additive length compared to the lithium secondary battery of Comparative Example 3 in which a linker was connected to the fourth carbon of propane sultone. This suggests that the additive of the present invention increases the area covered by the coating and exhibits excellent high-temperature storage properties.

Claims

1. A non-aqueous electrolyte comprising a lithium salt, an organic solvent, and a compound of the following chemical formula 1 as an additive: 【Chemistry 1】 In the above Chemical Formula 1, n is an integer of 0 or 1; R １ represents R, an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, OR', OCOR', F, and CH ２ PO(R) ２ any one selected from the group consisting of: R' is an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine, or PO(R) ２ any one selected from the group consisting of: R is a structure represented by the following chemical formula 2: 【Chemistry 2】 In Formula 2, Rx and Ry are each independently either H or F.

2. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is a compound of Chemical Formula 1-1: 【Transformation 3】 In the above chemical formula 1-1, R １ is F, R, or OR', and R' is any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine; R is a structure represented by the following chemical formula 2: 【Chemistry 4】 In Formula 2, Rx and Ry are each independently either H or F.

3. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is a compound of Chemical Formula 1-2: 【Transformation 5】 In the above chemical formula 1-2, X is —CH ２ - or -O-, R is a structure represented by the following chemical formula 2: 【Transformation 6】 In Formula 2, Rx and Ry are each independently either H or F.

4. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is a compound of Chemical Formula 1-3: 【Transformation 7】 In the above chemical formula 1-3, R １ is F, R, or OR', and R' is any one selected from the group consisting of an alkyl group having 1 to 10 carbon atoms which may be substituted with fluorine, an alkenyl group having 2 to 10 carbon atoms which may be substituted with fluorine, and an alkynyl group having 2 to 10 carbon atoms which may be substituted with fluorine; R is a structure represented by the following chemical formula 2: 【Transformation 8】 In Formula 2, Rx and Ry are each independently either H or F.

5. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is any one of compounds of the following Chemical Formulas 1-1a to 1-1f: 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 In the chemical formulas 1-1a to 1-1f, R is a structure represented by the following chemical formula 2-1. 【Chemistry 15】

6. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is any one of compounds of the following Chemical Formulas 1-2a and 1-2b: 【Chemistry 16】 【Chemistry 17】 In the chemical formulas 1-2a and 1-2b, R is a structure represented by the following chemical formula 2-1. [Chemistry 18]

7. 2. The nonaqueous electrolyte according to claim 1, wherein the compound of Chemical Formula 1 is any one of compounds of the following Chemical Formulas 1-3a to 1-3f: 【Chemistry 19】 【Chemistry 20】 【Chemistry 21】 【Chemistry 22】 【Chemistry 23】 【Chemistry 24】 In the chemical formulas 1-3a to 1-3f, R is a structure represented by the following chemical formula 2-1. 【Chemistry 25】

8. 8. The non-aqueous electrolyte according to claim 1, wherein the compound of Formula 1 is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the non-aqueous electrolyte.

9. The lithium salt is LiPF ６ , LiCl, LiBr, LiI, LiBF ４ , LiClO ４ , LiB １０ Cl １０ , LiAlCl ４ , LiAlO ２ , LiSO ３ CH ３ , LiSO ３ CF ３ , LiCO ２ CH ３ , LiCO ２ CF ３ , LiAsF ６ , LiSbF ６ , LiN(SO ２ F) ２ , LiN (SO ２ CF ２ CF ３ ) ２ , and LiN(SO ２ CF ３ ) ２ The non-aqueous electrolyte according to claim 1 , wherein the non-aqueous electrolyte is one or more selected from the group consisting of:

10. 8. The non-aqueous electrolyte according to claim 1, wherein the lithium salt is contained at a concentration of 0.5 M to 4.0 M.

11. 8. The nonaqueous electrolyte according to claim 1, wherein the organic solvent comprises at least one organic solvent selected from the group consisting of a cyclic carbonate organic solvent, a linear carbonate organic solvent, a linear ester organic solvent, and a cyclic ester organic solvent.

12. 8. The nonaqueous electrolyte according to claim 1, further comprising, as an additive, one or more compounds selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

13. A positive electrode and a negative electrode; A lithium secondary battery comprising the nonaqueous electrolyte according to claim 1 .

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