Non-aqueous electrolyte containing an additive for non-aqueous electrolyte and lithium secondary battery containing the same

Abstract

The present invention provides a non-aqueous electrolyte comprising an additive for a non-aqueous electrolyte, the additive comprising a repeating unit represented by chemical formulas 1 and 2, wherein X in chemical formula 1 is a perfluoroalkyl group having 1 to 10 carbon atoms, R 1 is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group; R in Chemical Formula 2 is an alkyl group having 1 to 10 carbon atoms substituted with one or more nitrile groups; R 2 is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group. JPEG2024531423000017.jpg52170

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0005270, filed on January 13, 2022, and all the contents disclosed in the document of the Korean Patent Application are incorporated herein by reference in their entirety.

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

Background Art

[0003] In recent years, the application fields of lithium secondary batteries have rapidly expanded not only to power supply for electronic devices such as electric, electronic, communication, and computer devices, but also to power storage and supply for large-area devices such as automobiles and power storage devices. Along with this, the demand for secondary batteries with high capacity, high output, and high stability is increasing.

[0004] In particular, in lithium secondary batteries for automotive applications, high capacity, high output, and long-term life characteristics are important. For increasing the capacity of secondary batteries, cathode active materials with high energy density but low stability, such as those with a high nickel content, may be used, or secondary batteries may be driven at high voltages.

[0005] However, when driving a secondary battery under the above conditions, as charge and discharge proceed, due to side reactions caused by deterioration of the electrolyte, the film formed on the surface of the positive / negative electrode or the structure of the electrode surface deteriorates, and transition metal ions can be eluted from the surface of the positive electrode. In this way, the eluted transition metal ions are electrodeposited on the negative electrode, reducing the passivation ability of the SEI, resulting in a problem of deterioration of the negative electrode.

[0006] Such a deterioration phenomenon of the secondary battery tends to accelerate when the potential of the positive electrode increases or the battery is exposed to high temperatures.

[0007] In addition, when a lithium-ion battery is used continuously for a long time or left at a high temperature, a so-called swelling phenomenon occurs in which gas is generated and the thickness of the battery increases. The amount of gas generated at this time is known to depend on the state of such SEI.

[0008] Therefore, in order to solve such problems, research and development have been conducted on a method that can suppress the elution of metal ions in the positive electrode, form a stable SEI film on the negative electrode, reduce the swelling phenomenon of the secondary battery, and enhance the stability at high temperatures.

Summary of the Invention

Problems to be Solved by the Invention

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

[0010] Another object of the present invention is to provide a non-aqueous electrolyte having enhanced stability at high temperatures by including the additive for non-aqueous electrolytes.

[0011] Furthermore, an object of the present invention is to provide a lithium secondary battery in which the high-temperature cycle characteristics and high-temperature storage characteristics are improved and various performances are enhanced by including the non-aqueous electrolyte.

Means for Solving the Problems

[0012] According to one embodiment, in order to achieve the above object, the present invention provides a non-aqueous electrolyte including an additive for non-aqueous electrolytes containing repeating units represented by the following Chemical Formula 1 and Chemical Formula 2.

[0013]

Chem.

[0014] In the above Chemical Formula 1, X is a perfluoroalkyl group having 1 to 10 carbon atoms, and R 1 is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group.

[0015]

Chemical formula

[0016] In the above Chemical Formula 2, R is an alkyl group having 1 to 10 carbon atoms substituted with at least one or more nitrile groups, and R 2 is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group.

[0017] According to another embodiment, the present invention provides a lithium secondary battery including the above non-aqueous electrolyte.

Advantages of the Invention

[0018] The polymer containing the repeating units represented by Chemical Formula 1 and Chemical Formula 2 provided as an additive for the non-aqueous electrolyte of the present invention can form a strong SEI (Solid Electrolyte Interphase) film having elasticity on the surface of the negative electrode. Therefore, by maintaining a strong SEI layer even at high temperatures, deterioration of the negative electrode can be prevented, and an additional SEI formation reaction due to decomposition of the solvent during the progress of the cycle can be suppressed.

[0019] In addition, the polymer provided as an additive for the non-aqueous electrolyte of the present invention contains a perfluoroalkyl group in the repeating unit of Chemical Formula 1, so that LiF inorganic matter is easily generated and a stable polymer-inorganic-based SEI layer can be formed.

[0020] Furthermore, the polymer provided as an additive for the non-aqueous electrolyte of the present invention contains a nitrile group in the repeating unit of Chemical Formula 2, so that it can be well electrodeposited on the negative electrode and the SEI layer can be easily formed.

[0021] Therefore, when the non-aqueous electrolyte of the present invention containing the polymer provided as an additive for the non-aqueous electrolyte of the present invention is used, an electrode-electrolyte interface that is stable even at high temperatures and has strong durability can be formed. Thus, a lithium secondary battery with improved high-temperature cycle characteristics and high-temperature storage characteristics and enhanced various performances can be realized.

Embodiments for Carrying Out the Invention

[0022] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. The inventors should interpret them in accordance with the meaning and concept consistent with the technical idea of the present invention in accordance with the principle that they can appropriately define the concept of the terms in order to explain their invention in the best way.

[0023] In this specification, terms such as "including", "comprising", or "having" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and should be understood not to preclude the presence or addition possibility of one or more other features, numbers, steps, components, or combinations thereof in advance.

[0024] In addition, in this specification, in the description of "carbon number a to b", "a" and "b" mean 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 alkylene group having 1 to 5 carbon atoms" means an alkylene group containing 1 to 5 carbon atoms, that is, -CH 2 -, -CH 2 CH 2 -, -CH 2 CH 2 CH 2 -, -CH 2 (CH 3 )CH-, -CH(CH 3 )CH 2 -, and -CH(CH 3 )CH 2 CH 2 - and the like.

[0025] In addition, in this specification, the term "alkyl group" means a branched or unbranched monovalent saturated hydrocarbon group.

[0026] In addition, in this specification, an alkyl group, an alkenyl group, an alkoxy group, a cycloalkyl group, a cycloalkenyl group, and an aryl group may or may not be substituted. The term "substituted" means that at least one or more hydrogens bonded to carbon are substituted with an element other than hydrogen, unless otherwise defined. For example, it means being substituted with an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, a heterocycloalkyl group having 3 to 12 carbon atoms, a heterocycloalkenyl group having 3 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, and the like.

[0027] Hereinafter, the present invention will be described in more detail.

[0028] [Non-aqueous electrolyte] The non-aqueous electrolyte according to the present invention contains, as an additive, a polymer containing repeating units represented by the following Chemical Formula 1 and Chemical Formula 2. A secondary battery containing the non-aqueous electrolyte of the present invention can suppress deterioration due to interfacial reactions at high temperatures and can have excellent high-temperature cycle characteristics and high-temperature storage characteristics.

[0029] [Chemical formula]

[0030] [Chemical formula]

[0031] The repeating unit of Chemical Formula 1 contained in the polymer provided as an additive for the non-aqueous electrolyte of the present invention contains a perfluoroalkyl group, so that LiF inorganic matter is easily generated and a stable polymer-inorganic-based SEI layer can be formed. Therefore, it is possible to suppress a decrease in the passivation ability of SEI at high temperatures and prevent deterioration of the negative electrode.

[0032] Furthermore, the polymer provided as an additive for the non-aqueous electrolyte of the present invention contains a nitrile group in the repeating unit of Chemical Formula 2, so that it can be well electrodeposited on the negative electrode and the SEI layer can be easily formed. As a result, a strong SEI layer can be formed rapidly.

[0033] In Chemical Formula 1, X may be a perfluoroalkyl group having 1 to 10 carbon atoms. Preferably, X in Chemical Formula 1 may be a linear or branched perfluoroalkyl group having 1 to 5 carbon atoms, and most preferably, X in Chemical Formula 1 may be a linear perfluoroalkyl group having 1 to 3 carbon atoms.

[0034] In Chemical Formula 2, R may be an alkyl group having 1 to 10 carbon atoms substituted with one or more nitrile groups. Preferably, R in Chemical Formula 2 has 1 to 5 carbon atoms and may be a linear or branched alkyl group substituted with one or more nitrile groups. Most preferably, R in Chemical Formula 2 may be an alkyl group having 1 to 3 carbon atoms substituted with one or more nitrile groups.

[0035] In Chemical Formulas 1 and 2, R 1 and R 2 may each independently be any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group. Preferably, R 1 and R 2 in Chemical Formulas 1 and 2 may each independently be any one selected from the group consisting of H and an alkyl group having 1 to 10 carbon atoms. Most preferably, R 1 and R 2 in Chemical Formulas 1 and 2 may be H.

[0036] The non-aqueous electrolyte according to the present invention may contain, as an additive, a polymer represented by the following Chemical Formula 3.

[0037]

Chemical Formula

[0038] In Chemical Formula 3, X may be a perfluoroalkyl group having 1 to 10 carbon atoms. Preferably, X in Chemical Formula 3 may be a linear or branched perfluoroalkyl group having 1 to 5 carbon atoms. Most preferably, X in Chemical Formula 3 may be a linear perfluoroalkyl group having 1 to 3 carbon atoms.

[0039] In Chemical Formula 3, R may be an alkyl group having 1 to 10 carbon atoms substituted with one or more nitrile groups. Preferably, R in Chemical Formula 3 has 1 to 5 carbon atoms and may be a linear or branched alkyl group substituted with one or more nitrile groups. Most preferably, R in Chemical Formula 3 may be an alkyl group having 1 to 3 carbon atoms substituted with one or more nitrile groups.

[0040] In Chemical Formula 3, m and n may each independently be an integer from 1 to 100. Preferably, m may be an integer from 10 to 50, and n may be an integer from 60 to 100. Most preferably, m may be from 10 to 30 and n may be from 70 to 90. When m and n in Chemical Formula 3 satisfy the above ranges, there is an advantage that when forming a polymer-inorganic-based SEI layer with the additive of the present invention, the amount of inorganic components such as LiF can be appropriately adjusted.

[0041] The additive for non-aqueous electrolyte according to the present invention is contained in an amount of 0.01 parts by weight to 5 parts by weight, preferably 0.05 parts by weight to 2 parts by weight, more preferably 0.10 parts by weight to 1.5 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte. When the content of the polymer containing the repeating units represented by Chemical Formula 1 and Chemical Formula 2 satisfies the above range, the effect of forming a film on the negative electrode is sufficient, and there is an effect of excellent high-temperature life characteristics and high-temperature storage characteristics.

[0042] The non-aqueous electrolyte according to the present invention may further contain a lithium salt, an organic solvent, or other electrolyte additives.

[0043] The lithium salt is used as an electrolyte salt in a lithium secondary battery and is used as a medium for transmitting ions. Usually, as the lithium salt, for example, as a cation, it contains Li + and as an anion, F - 、Cl - 、Br - 、I - 、NO 3 - 、N(CN) 2- , BF 4 - , ClO 4 - , B 10 Cl 10 - , AlCl 4 - , AlO 2 - , PF 6 - , CF 3 SO 3 - , CH 3 CO 2 - , CF 3 CO 2 - , AsF 6 - , SbF 6 - , CH 3 SO 3 - , (CF 3 CF 2 SO 2 ) 2 N - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , 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 - , (CF 3 ) 6 P - , C 4 F 9 SO 3 - , CF 3 CF 2 SO 3 - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , CF 3 (CF 2 ) 7 SO 3 - , and at least any one selected from the group consisting of SCN - are included.

[0044] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF 4 , LiClO 4 , LiB 10 Cl 10 , LiAlCl 4 , LiAlO 2 , LiPF 6 , LiCF 3 SO 3 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiCH 3 SO 3 , LiN(SO 2 F) 2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiN(SO 2 CF 2 CF 3 ) 2(Lithium bis(perfluoroethanesulfonyl)imide; LiBETI), and LiN(SO 2 CF 3 ) 2 (Lithium bis(trifluoromethanesulfonyl)imide; LiTFSI), or a single substance or a mixture of two or more selected from the group consisting thereof may be included. In addition to these, lithium salts usually used in the electrolyte of lithium secondary batteries can be used without limitation.

[0045] The lithium salt can be appropriately changed within the usually usable range. However, in order to obtain the optimal effect of forming a film for preventing corrosion of the electrode surface, it may be contained in the electrolyte at a concentration of 0.5 M to 4.0 M, preferably 1.0 M to 3.0 M, more preferably 1.5 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics during high-temperature storage of the lithium secondary battery is sufficient, and the viscosity of the non-aqueous electrolyte is appropriate and the electrolyte impregnation property can be improved.

[0046] The non-aqueous organic solvent may contain at least one organic solvent selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, linear ester-based organic solvents, and cyclic ester-based organic solvents.

[0047] The additive according to the present invention is particularly effective when using a cyclic carbonate solvent. When using a conventional electrolyte additive together with a cyclic carbonate solvent, the SEI film formed by the decomposition of the cyclic carbonate solvent has a problem that it is difficult to maintain the SEI film due to the volume change of the negative electrode occurring during the progress of the cycle, and the decomposition of the solvent continues to occur. As a result, there has been a problem that the ionic conductivity of the electrolytic solution decreases and the cycle characteristics deteriorate. However, when using the polymer according to the present invention as an additive together with a cyclic carbonate solvent, a strong SEI film can be formed, and there is an effect that the cycle characteristics are maintained high.

[0048] The cyclic carbonate-based organic solvent is a high-viscosity organic solvent with a high dielectric constant, which easily dissociates lithium salts in the electrolyte. Specific examples thereof include at least one or more organic solvents selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. Among them, fluoroethylene carbonate may be included.

[0049] In addition, the linear carbonate-based organic solvent is an organic solvent having a low viscosity and a low dielectric constant. Representative examples thereof include at least one or more organic solvents 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. Specifically, diethyl carbonate (DEC) may be included.

[0050] In addition, in order to produce an electrolyte having a high ionic conductivity, the organic solvent may further include at least one ester-based organic solvent selected from the group consisting of a linear ester-based organic solvent and a cyclic ester-based organic solvent in at least one carbonate-based organic solvent selected from the group consisting of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent.

[0051] Specific examples of such linear ester-based organic solvents include at least one or more organic solvents selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0052] In addition, examples of the cyclic ester-based organic solvent include at least one or more organic solvents selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0053] On the other hand, the organic solvent may be added and used without being limited to the organic solvents commonly used in non-aqueous electrolytes, if necessary. For example, it may further contain at least one or more organic solvents such as ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents.

[0054] As the ether-based solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more thereof can be used, but it is not limited thereto.

[0055] The glyme-based solvent has a higher dielectric constant and a lower surface tension than linear carbonate-based organic solvents and has less reactivity with metals. It may contain at least one or more selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraethylene glycol dimethyl ether (TEGDME), but is not limited thereto.

[0056] The nitrile-based 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.

[0057] In addition, the non-aqueous electrolyte of the present invention may further contain a known electrolyte additive in the non-aqueous electrolyte as necessary to prevent the non-aqueous electrolyte from being decomposed in a high-output environment and causing the collapse of the negative electrode, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, battery expansion suppression effect at high temperature, etc.

[0058] Such other electrolyte additives may include, as representative examples thereof, at least one or more SEI film-forming additives 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.

[0059] Examples of the cyclic carbonate compound include vinylene carbonate (VC) or vinyl ethylene carbonate.

[0060] Examples of the halogen-substituted carbonate compound include fluoroethylene carbonate (FEC).

[0061] Examples of the sultone compound include at least one or more compounds selected from the group consisting of 1,3-propanesultone (PS), 1,4-butanesultone, ethenesultone, 1,3-propenesultone (PRS), 1,4-butenesultone, and 1-methyl-1,3-propenesultone.

[0062] Examples of the sulfate compound include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0063] Examples of the phosphate compound include one or more compounds selected from the group consisting of lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tetramethyltrimethylsilyl phosphate, trimethylsilyl phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(trifluoroethyl) phosphite.

[0064] Examples of the borate compound include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), or lithium bisoxalate borate (LiB(C 2 O 4 ) 2 , LiBOB).

[0065] Examples of the nitrile compound include at least one or more compounds 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.

[0066] Examples of the benzene compound include fluorobenzene, examples of the amine compound include triethanolamine or ethylenediamine, and examples of the silane compound include tetravinylsilane.

[0067] The lithium salt compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and examples thereof include lithium difluorophosphate (LiDFP), LiPO 2 F 2 , or LiBF 4 .

[0068] Among such other electrolyte additives, when further containing a combination of vinylene carbonate (VC), 1,3 - propane sultone (PS), ethylene sulfate (Esa), and lithium difluorophosphate (LiDFP), a stronger SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, suppressing the generation of gases that can be generated by the decomposition of the electrolyte at high temperatures, and improving the high - temperature stability of the secondary battery.

[0069] On the other hand, two or more of the other electrolyte additives may be mixed and used. Based on the total weight of the non - aqueous electrolyte, they may be contained in an amount of 0.050 to 20% by weight, specifically 0.10 to 15% by weight, and preferably 0.30 to 10% by weight. When the content of the other electrolyte additives satisfies the above range, better ion conductivity and cycle characteristics improvement effects can be obtained.

[0070] [Lithium secondary battery] The present invention also provides a lithium secondary battery containing the non - aqueous electrolyte.

[0071] Specifically, the lithium secondary battery includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and the aforementioned non - aqueous electrolyte.

[0072] At this time, the lithium secondary battery of the present invention can be manufactured by a conventional method known in the art. For example, after forming an electrode assembly in which a positive electrode, a negative electrode, and a separator are sequentially laminated between the positive electrode and the negative electrode, the electrode assembly is inserted into the interior of a battery case, and the non - aqueous electrolyte according to the present invention is injected to manufacture it.

[0073] (1) Positive electrode The positive electrode can be manufactured 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.

[0074] 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, fired carbon, or those obtained by surface treatment of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used.

[0075] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium. Specifically, it 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., LiMnO 2 、LiMn 2 O 4 etc.), a lithium-cobalt-based oxide (e.g., LiCoO 2 etc.), a lithium-nickel-based oxide (e.g., LiNiO 2 etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O 2 (where 0 < Y < 1), LiMn 2-Z Ni Z O 4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O 2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O 4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Co q Mn r )O 2 (where 0 < p < 1, 0 < q < 1, 0 < r < 1, p + q + r = 1) or Li(Ni p1 Coq1 Mn r1 )O 4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r1 < 2, p1 + q1 + r1 = 2), etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O 2 (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 the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r2 < 1, 0 < s2 < 1, and p2 + q2 + r2 + s2 = 1), etc.) and the like, and any one or two or more of these compounds may be included.

[0076] Among them, from the viewpoint of being able to enhance the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO 2 , LiMnO 2 , LiNiO 2 , lithium nickel manganese cobalt oxide (e.g., Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O 2 , Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 , and Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 etc.) and the like, and any one or two or more of these mixtures may be used.

[0077] The positive 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 matter excluding the solvent in the positive electrode mixture slurry.

[0078] The binder is a component that assists in binding the active material, conductive material, etc. and binding to the current collector.

[0079] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluorine rubber, various copolymers, and the like.

[0080] 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 content excluding the solvent in the positive electrode mixture slurry.

[0081] 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 to 20% by weight based on the total weight of the solid content in the positive electrode mixture slurry. Such conductive materials are not particularly limited as long as they do not cause a chemical change in the battery and have conductivity. For example, carbon powders such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives can be used.

[0082] Generally, the conductive material 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 solids excluding the solvent in the positive electrode active material slurry.

[0083] The solvent may contain an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a suitable viscosity when the positive electrode active material, and optionally a binder and a conductive material, etc. are included. For example, it may be included such that the concentration of the solid content including the positive electrode active material, and optionally a binder and a conductive material, is 50 to 95% by weight, preferably 70 to 95% by weight, more preferably 70 to 90% by weight.

[0084] (2) Negative electrode The negative electrode can be produced, for example, by coating a negative electrode current collector with a negative electrode active material slurry containing a negative electrode active material, a binder, a conductive material, and a solvent, etc., or a graphite electrode made of carbon (C) or the metal itself can be used as the negative electrode.

[0085] For example, when producing a negative electrode by coating a negative electrode current collector with a negative electrode active material slurry, the negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, a surface-treated product with carbon, nickel, titanium, silver, etc. on the surface of copper or stainless steel, an aluminum-cadmium alloy, etc. may be used. Also, similar to the positive electrode current collector, the binding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and it may be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric body, etc.

[0086] Further, the negative electrode active material may contain at least one or more selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal, an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and undoping lithium, and a transition metal oxide.

[0087] The carbon material capable of reversibly intercalating / deintercalating lithium ions is not particularly limited as long as it is a carbon-based negative electrode active material generally used in lithium ion secondary batteries, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination of these. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, and calcined coke.

[0088] 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.

[0089] 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.

[0090] Examples of the metal composite oxide include PbO, PbO 2 , Pb 2 O 3 , Pb 3 O 4 , Sb 2 O 3 , Sb 2O 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, Group 3 of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) can be selected from the group consisting of.

[0091] As substances that can dope and undope the lithium, Si, SiO x (0 < x ≦ 2), Si-Y alloy (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO 2 、Sn-Y (wherein Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), etc. can be mentioned, and at least one of these and SiO 2 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 combinations thereof.

[0092] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, and the like.

[0093] The additive according to the present invention is particularly effective when Si or SiO x (0 < x ≤ 2) is used as the negative electrode active material. Specifically, when a Si-based negative electrode active material is used, if a strong SEI layer is not formed on the surface of the negative electrode during initial activation, the life characteristics will be promoted to decline due to intense volume expansion - contraction during the progress of the cycle. However, the additive according to the present invention can form a strong SEI layer while having elasticity, so that a secondary battery using a Si-based negative electrode active material can have excellent life characteristics and storage characteristics.

[0094] The negative electrode active material may be contained in an amount of 50 to 99% by weight, preferably 60 to 99% by weight, more preferably 70 to 98% by weight based on the total weight of the solid content in the negative electrode binder slurry.

[0095] Examples of the binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene - propylene - diene monomer, sulfonated ethylene - propylene - diene monomer, styrene - butadiene rubber, fluorine rubber, various copolymers thereof, and the like. Specifically, styrene - butadiene rubber (SBR) - carboxymethyl cellulose (CMC) can be used from the viewpoint of high thickening property.

[0096] Usually, 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.

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

[0098] The conductive material 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 solids excluding the solvent in the negative electrode binder slurry.

[0099] The solvent may contain 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, etc. are included. For example, it may be included such that the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material, is 50% to 95% by weight, preferably 70% to 90% by weight.

[0100] When using the metal itself as the negative electrode, it can be manufactured by a method such as physically bonding, rolling, or vapor depositing the metal on the metal thin film itself or the negative electrode current collector. As the vapor deposition method, a method of electrically vapor depositing or chemically vapor depositing (chemical vapor deposition) the metal can be used.

[0101] For example, the metal film itself or the metal joined / rolled / vapor-deposited on the negative electrode current collector may include one metal selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In), or an alloy of two metals, etc.

[0102] (3) Separator Also, as the separator, a normal porous polymer film conventionally used as a separator, for example, a porous polymer film made of a polyolefin-based polymer such as a homopolymer of ethylene, a homopolymer of propylene, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer may be used alone or in a laminated form, or a normal porous non-woven fabric, for example, a non-woven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc. may be used, but it is not limited thereto. Further, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer substance may be used, and it may be selectively used as a single-layer or multi-layer structure.

[0103] Specifically, as the separator included in the electrode assembly of the present invention, an SRS (safety reinforced separator) separator having a coating layer containing a ceramic component or a polymer substance formed thereon may be used in order to ensure heat resistance or mechanical strength.

[0104] Specifically, the separator included in the electrode assembly of the present invention includes a porous separator substrate and a porous coating layer entirely coated on one or both sides of the separator substrate, and the coating layer may include a mixture of inorganic particles selected from metal oxides, metalloid oxides, metal fluorides, metal hydroxides, and combinations thereof, and a binder polymer that connects and fixes the inorganic particles to each other.

[0105] The coating layer contains, as inorganic particles, Al 2O 3 , SiO 2 , TiO 2 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , Y 2 O 3 , SrTiO 3 , BaTiO 3 , Mg(OH) 2 It may contain one or more selected from MgF. Here, the inorganic particles can improve the thermal stability of the separator. That is, the inorganic particles can prevent the separator from shrinking at high temperatures. And the binder polymer can fix the inorganic particles and also improve the mechanical stability of the separator.

[0106] The outer shape of the lithium secondary battery of the present invention is not particularly limited, and it may be a cylindrical shape, a rectangular shape, a pouch shape, a coin shape, etc. using a can.

[0107] Hereinafter, the present invention will be described more specifically with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope of the description and the scope of the technical idea, and it goes without saying that such modifications and changes belong to the scope of the appended claims.

[0108] 〔Synthesis Example〕 Under an argon (Ar) atmosphere, 4.0 mmol of AgOTf, 6.0 mmol of KF, 4.0 mmol of 2-fluoropyridine, and 4.0 mmol of TMSCF 3 were placed in an EtOAc solvent and stirred at room temperature for 12 hours. To this, 3.0 mmol of Selectfluor was added and reacted, and then 0.02 mol of PVA-CN was added and reacted. After the reaction was completed, the AgF by-product was filtered, the remaining polymer solution was precipitated in distilled water, and the precipitate was dried in vacuo to obtain a polymer. The obtained polymer was a substance represented by Chemical Formula 3.

[0109] [Chemical formula] (X is CF 3 and R is CH 2 CH 2 CN, where m = 20 and n = 80)

[0110] [Example] Example 1 (Manufacture of non-aqueous electrolyte) LiPF was dissolved in an organic solvent (fluoroethylene carbonate (FEC): diethyl carbonate (DEC) = 10:90 by volume ratio) to a concentration of 1.5 M to produce a non-aqueous solvent. 0.1 g of the polymer of Chemical Formula 3 below was added to 99.9 g of the non-aqueous solvent to produce a non-aqueous electrolyte. 6

[0111] [Chemical formula] (X is CF 3 and R is CH 2 CH 2 CN, where m = 20 and n = 80)

[0112] (Manufacture of lithium secondary battery) A cathode active material (LiNi 0.85 Co 0.05 Mn 0.08 Al 0.02 O 2 ), a conductive material (carbon nanotube), and a binder (polyvinylidene fluoride) were added to N-methyl-2-pyrrolidone (NMP), which is a solvent, at a weight ratio of 97.74:0.7:1.56 to produce a cathode slurry (solid content: 75.5% by weight). The cathode slurry was applied to one side of a cathode current collector (Al thin film) with a thickness of 15 μm, and drying and roll press were performed to produce a cathode.

[0113] ​The negative electrode active material (silicon; Si), the conductive material (carbon black), and the binder (styrene-butadiene rubber (SBR)-carboxymethyl cellulose (CMC)) were added to N-methyl-2-pyrrolidone (NMP), which is a solvent, at a weight ratio of 70:20.3:9.7 to produce a negative electrode slurry (solid content: 26% by weight). The negative electrode slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 15 μm, followed by drying and roll pressing to produce a negative electrode.

[0114] In a dry room, after interposing a polyolefin-based porous separator coated with inorganic particles Al 2 O 3 between the positive electrode and the negative electrode manufactured above, the non-aqueous electrolyte manufactured above was injected to produce a secondary battery.

[0115] Example 2 A secondary battery was manufactured in the same manner as in Example 1, except that 0.3 g of the polymer of Chemical Formula 3 was added to 99.7 g of the non-aqueous solvent manufactured in Example 1 to produce a non-aqueous electrolyte.

[0116] Example 3 A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the polymer of Chemical Formula 3 was added to 99.5 g of the non-aqueous solvent manufactured in Example 1 to produce a non-aqueous electrolyte.

[0117] Example 4 A secondary battery was manufactured in the same manner as in Example 1, except that 1.0 g of the polymer of Chemical Formula 3 was added to 99.0 g of the non-aqueous solvent manufactured in Example 1 to produce a non-aqueous electrolyte.

[0118] Example 5 LiPF 6 was dissolved in an organic solvent (fluoroethylene carbonate (FEC): diethyl carbonate (DEC) = 10:90 volume ratio) to a concentration of 1.5 M to produce a non-aqueous solvent, and 0.1 g of the polymer of Chemical Formula 4 was added to 99.9 g of the non-aqueous solvent to produce a non-aqueous electrolyte.

[0119] [Chemical formula] (R 1 is CH 3 and R 2 is OCH 3 and X is CF 3 and R is CH 2 CH 2 CN, where m = 20 and n = 80)

[0120] A secondary battery was manufactured in the same manner as in Example 1, except for manufacturing the non-aqueous electrolyte.

[0121] Example 6 LiPF 6 was dissolved in an organic solvent (fluoroethylene carbonate (FEC): diethyl carbonate (DEC) = 10:90 by volume ratio) to a concentration of 1.5 M to produce a non-aqueous solvent. 0.1 g of the polymer of Chemical Formula 4 below was added to 99.9 g of the non-aqueous solvent to produce a non-aqueous electrolyte.

[0122] [Chemical formula] (R 1 is F, and R 2 is CH 2 CHCH 2 and X is CF 3 and R is CH 2 CH 2 CN, where m = 20 and n = 80)

[0123] A secondary battery was manufactured in the same manner as in Example 1, except for manufacturing the non-aqueous electrolyte.

[0124] Comparative Example 1 A secondary battery was manufactured in the same manner as in Example 1, except for manufacturing a non-aqueous electrolyte using 100 g of the non-aqueous solvent manufactured in Example 1.

[0125] [Experimental Example 1 - Evaluation of High-Temperature Cycle Characteristics] The cycle characteristics of each of the secondary batteries manufactured in Examples 1 to 6 and Comparative Example 1 were evaluated.

[0126] Specifically, each of the batteries manufactured in Examples 1 to 6 and Comparative Example 1 was charged to 4.2 V at a constant current of 1 C at 45 °C and discharged to 3.0 V at a constant current of 0.5 C, which was defined as one cycle. After performing charge and discharge 250 times, the capacity retention rate with respect to the initial capacity after one cycle was measured. The results are shown in Table 1 below.

[0127] [Table 1]

[0128] As shown in Table 1, Examples 1 to 6 using the additive for non-aqueous electrolytes of the present invention had a higher capacity retention rate and better life characteristics than Comparative Example 1 that did not use it.

[0129] [Experimental Example 2 - Evaluation of High-Temperature Storage Characteristics] The high-temperature storage characteristics of each of the secondary batteries manufactured in Examples 1 to 6 and Comparative Example 1 were evaluated.

[0130] Specifically, each of the secondary batteries of Examples 1 to 6 and Comparative Example 1 was fully charged to 4.2 V and then stored at 60 °C for 8 weeks.

[0131] Before storage, the resistance of the fully charged secondary battery was measured and set as the resistance of the initial secondary battery.

[0132] After 8 weeks, the resistance of the stored secondary battery was measured, and the resistance increased during the 8-week storage period was calculated. The percentage ratio of the increased resistance to the resistance of the initial secondary battery was calculated to derive the resistance increase rate after 8 weeks. The results are shown in Table 2 below.

[0133] [Table 2]

[0134] As shown in Table 2 above, the secondary batteries of Examples 1 to 6 had a lower resistance increase rate after 8 weeks compared to the secondary battery of Comparative Example 1, and stable performance at high temperatures was confirmed.

Claims

1. A non-aqueous electrolyte containing an additive for non-aqueous electrolytes, which contains a repeating unit represented by the following Chemical Formula 1 and a repeating unit represented by the following Chemical Formula 2: 【Chemical 1】 (In the above Chemical Formula 1, X is a perfluoroalkyl group having 1 to 10 carbon atoms, R １ is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group, [Chemical Formula 2] in the above Chemical Formula 2, R is an alkyl group having 1 to 10 carbon atoms substituted with one or more nitrile groups, R ２ is any one selected from the group consisting of H, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a halogen atom, and a nitrile group.

2. The non-aqueous electrolyte according to Claim 1, wherein the additive for non-aqueous electrolytes is represented by the following Chemical Formula 3: [Chemical Formula 3] (In the above Chemical Formula 3, X is a perfluoroalkyl group having 1 to 10 carbon atoms, R is an alkyl group having 1 to 10 carbon atoms substituted with one or more nitrile groups, m and n are each independently an integer from 1 to 100.)

3. wherein X is CF ３ and R is CH ２ CH ２ CN, the non-aqueous electrolyte according to claim 1.

4. Wherein X is CF ３ and R is CH ２ CH ２ CN, and the non-aqueous electrolyte according to claim 2.

5. The non-aqueous electrolyte according to Claim 2, wherein m is an integer from 10 to 50 and n is an integer from 60 to 100.

6. The non-aqueous electrolyte according to Claim 1, wherein the additive for non-aqueous electrolytes is contained in a content of 0.01 part by weight to 5 parts by weight with respect to 100 parts by weight of the non-aqueous electrolyte.

7. LiCl, LiBr, LiI, LiBF ４ , LiClO ４ , LiB １０ Cl １０ , LiAlCl ４ , LiAlO ２ , LiPF ６ , LiCF ３ SO ３ , LiCH ３ CO ２ , LiCF ３ CO ２ , LiAsF ６ , LiSbF ６ , LiCH ３ SO ３ , LiN(SO ２ F) ２ , LiN(SO ２ CF ２ CF ３ ) ２ , and at least one or more lithium salts selected from the group consisting of LiN(SO ２ CF ３ ) ２ The non-aqueous electrolyte according to claim 1, further comprising

8. The non-aqueous electrolyte according to Claim 7, wherein the lithium salt is contained at a concentration of 0.5 M to 4.0 M.

9. The non-aqueous electrolyte according to Claim 1, further comprising an organic solvent.

10. The non-aqueous electrolyte according to Claim 9, wherein the organic solvent includes a cyclic carbonate-based organic solvent.

11. The non-aqueous electrolyte according to Claim 10, wherein the cyclic carbonate-based organic solvent is fluoroethylene carbonate (FEC).

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

13. A positive electrode, a negative electrode, and the non-aqueous electrolyte according to Claim 1, a lithium secondary battery.

14. The negative electrode contains SiO as a negative electrode active material ｘ The lithium secondary battery according to claim 13, wherein (0 ≦ x ≦ 2) is included.

15. The lithium secondary battery according to Claim 13, wherein the additive for non-aqueous electrolytes is represented by the following Chemical Formula 3: 【Chemical 4】 (In the chemical formula 3, X is CF ３ and R is CH ２ CH ２ CN, m and n are each independently an integer from 1 to 100.)

Images