The electrolyte does not contain water, and lithium secondary batteries include this electrolyte.

Abstract

The invention relates to a non-aqueous electrolyte and a lithium secondary battery comprising such electrolyte. The non-aqueous electrolyte under the invention comprises lithium salt; an organic solvent and an additive. The organic solvent comprises a primary organic solvent and a secondary organic solvent, the primary organic solvent being possible to be CFH2CFHCFH2, and the secondary organic solvent being possible to be a cyclic carbonate-based organic solvent.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same

[0001] Cross-citation with related application(s)

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0057211, filed April 29, 2024, and Korean Patent Application No. 10-2025-0055788, filed April 28, 2025, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery including the same.

[0006] Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing.

[0007] For example, as lithium secondary batteries are developed to have high capacity and high output, the probability of abnormal temperature rises due to various reasons during the charging and discharging process is increasing, which can lead to the so-called thermal runaway phenomenon in which sparks explode at high temperatures, and in case of thermal runaway, the fire is not easily extinguished, etc. Safety issues are recognized as one of the more important issues to be resolved in high capacity and high output lithium secondary batteries.

[0008] The present invention seeks to provide a non-aqueous electrolyte for a lithium secondary battery, which can suppress decomposition of the non-aqueous electrolyte and reduce gas generation during operation of the lithium secondary battery and / or during high-temperature storage.

[0009] A lithium secondary battery including a non-aqueous electrolyte according to the present invention provides improved overall performance by improving high-temperature cycle characteristics and high-temperature storage characteristics.

[0010] [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the organic solvent comprises a first organic solvent and a second organic solvent, the first organic solvent is CFH2CFHCFH2, and the second organic solvent is a cyclic carbonate-based organic solvent.

[0011] [2] The present invention provides a non-aqueous electrolyte in which, in the above [1], the first organic solvent is included in an amount of 5 to 40 volume% based on the total volume of the organic solvent.

[0012] [3] The present invention provides a non-aqueous electrolyte in which, in the above [1] or [2], the second organic solvent is included in an amount of 5 to 40 volume% based on the total volume of the organic solvent.

[0013] [4] The present invention provides a non-aqueous electrolyte in at least one of the above [1] to [3], wherein the cyclic carbonate-based organic solvent is ethylene carbonate or propylene carbonate.

[0014] [5] The present invention provides a non-aqueous electrolyte in at least one of the above [1] to [4], wherein the organic solvent further includes a third organic solvent, and the third organic solvent is a linear carbonate-based organic solvent.

[0015] [6] The present invention provides a non-aqueous electrolyte, wherein in at least one of the above [1] to [5], the linear carbonate-based organic solvent includes at least one selected from dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate.

[0016] [7] The present invention provides a non-aqueous electrolyte comprising LiPF6 in at least one of the above [1] to [6].

[0017] [8] The present invention provides a non-aqueous electrolyte in which, in at least one of the above [1] to [7], the additive is at least one selected from a cyclic carbonate compound, a halogen-substituted carbonate compound, a sultone compound, a sulfate compound, a phosphate compound, a borate compound, a nitrile compound, a benzene compound, an amine compound, a silane compound, and a lithium salt compound.

[0018] [9] The present invention provides a non-aqueous electrolyte, wherein in at least one of the above [1] to [8], the additive further comprises a combination of vinylene carbonate (VC), 1,3-propane sultone (PS) or 1,3-propene sultone (PRS).

[0019]

[0010] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte according to claim 1.

[0020]

[0011] The present invention provides a lithium secondary battery in which, in the above

[0010] , the positive electrode includes a lithium nickel cobalt manganese oxide as a positive electrode active material.

[0021]

[0012] In the present invention, in the above

[0010] or

[0011] , the negative electrode is SiO as a negative electrode active material. x (0 <x<2) 또는 SiC를 포함하는 리튬 이차 전지를 제공한다.

[0022]

[0013] The present invention provides a method for producing a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the organic solvent comprises a first organic solvent and a second organic solvent, the first organic solvent uses CFH2CFHCFH2, and the second organic solvent uses a cyclic carbonate-based organic solvent.

[0023]

[0014] The present invention provides a method for producing a non-aqueous electrolyte, wherein, in the above

[0013] , the first organic solvent is included in an amount of 5 to 40 volume% relative to the total organic solvent.

[0024]

[0015] The present invention provides a method for producing a non-aqueous electrolyte, wherein in the above

[0013] or

[0014] , the second organic solvent is included in an amount of 5 to 40 volume% based on the total volume of the organic solvent.

[0025]

[0016] The present invention provides a method for producing a non-aqueous electrolyte, wherein, in at least one of the above

[0013] to

[0015] , the cyclic carbonate-based organic solvent uses ethylene carbonate or propylene carbonate.

[0026]

[0017] The present invention provides a method for producing a non-aqueous electrolyte, wherein in at least one of the above

[0013] to

[0016] , the organic solvent further includes a third organic solvent, and the third organic solvent uses a linear carbonate-based organic solvent.

[0027]

[0018] The present invention provides a method for producing a non-aqueous electrolyte, wherein, in the above

[0013] to

[0017] , the linear carbonate-based organic solvent includes at least one selected from dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate.

[0028] The non-aqueous electrolyte of the present invention comprises CFH2CFHCFH2 as a cosolvent together with a cyclic carbonate solvent having a high lithium transport rate, thereby having the effect of suppressing the decomposition of the cyclic carbonate solvent and the decomposition of CFH2CFHCFH2 itself. As a result, the generation of gases generated by electrolyte side reactions during operation of a lithium secondary battery can be reduced. In addition, the non-aqueous electrolyte of the present invention comprises CFH2CFHCFH2 as a cosolvent together with a cyclic carbonate solvent, thereby maintaining high ionic conductivity of the electrolyte, thereby having an excellent effect of improving output characteristics. In addition, when the non-aqueous electrolyte of the present invention is used, electrolyte side reactions at the negative electrode can be suppressed, thereby suppressing cell deterioration.

[0029] Accordingly, the lithium secondary battery of the present invention has the effect of not deteriorating overall performance even when driven while exposed to high voltage and high temperature for a long period of time.

[0030] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0031] Figure 1 shows the structure of a lithium secondary battery according to one embodiment of the present invention.

[0032] FIG. 2 is a drawing for explaining an automobile including a battery pack composed of the lithium secondary battery of FIG. 1.

[0033] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0034]

[0035] Description of the symbol

[0036] 100: Lithium secondary battery

[0037] 110: Positive

[0038] 120: Cathode

[0039] 130: Membrane

[0040] 140: Non-aqueous electrolyte

[0041] 150: Battery case

[0042] 200: Battery Pack

[0043] 300: Car

[0044] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0045] It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0046] In addition, in the description of "carbon atoms a to b" in the present specification, "a" and "b" refer to the number of carbon atoms included in a specific functional group. That is, the functional group may include "a" to "b" carbon atoms. For example, "alkylene group having 1 to 5 carbon atoms" refers to an alkylene group including 1 to 5 carbon atoms, i.e., -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, or -CH(CH3)CH2CH2-.

[0047] In addition, all alkyl groups in this specification may be substituted or unsubstituted. The term "substituted" as used herein, unless otherwise defined, means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, it means that it is replaced with a halogen atom, a nitro group, a nitrile group, etc.

[0048] Among the various applications of lithium secondary batteries, for example, high-capacity, high-power, and long-life characteristics are becoming increasingly important for lithium secondary batteries used in automobiles. Typically, linear carbonate organic solvents, which possess both high dielectric constants and high viscosity, are selected as electrolyte solvents for high-power lithium secondary batteries, along with cyclic carbonate organic solvents, which possess high viscosity and low dielectric constants.

[0049] However, linear carbonate-based organic solvents are easily reduced and decomposed at the negative electrode to generate hydrocarbon gases, and can cause many side reactions at the negative electrode, which can cause problems such as deterioration in the performance and stability of lithium secondary batteries containing them.

[0050] This deterioration phenomenon of secondary batteries tends to accelerate when the potential of the positive electrode increases or when the battery is exposed to high temperatures.

[0051] Taking these points into consideration, the present invention proposes a technology that can reduce the swelling phenomenon of a lithium secondary battery and increase stability at high temperatures.

[0052]

[0053] Hereinafter, the present invention will be described in detail.

[0054] The non-aqueous electrolyte according to the present invention, the lithium secondary battery including the same, and the method for manufacturing the non-aqueous electrolyte include at least one of the following disclosed configurations, and may include any combination between technically possible configurations among the following configurations.

[0055]

[0056] Referring to FIG. 1, a lithium secondary battery (100) according to one embodiment of the present invention includes an electrode assembly comprising a positive electrode (110), a negative electrode (120) facing the positive electrode (110), a separator (130) interposed between the positive electrode (110) and the negative electrode (120), and a battery case (150) that accommodates a non-aqueous electrolyte (140) and the electrode assembly and the non-aqueous electrolyte (140).

[0057] The above lithium secondary battery (100) can be manufactured by housing the electrode assembly in a battery case (150) and then injecting the non-aqueous electrolyte (140) described above.

[0058] A lithium secondary battery (100) according to one embodiment of the present invention may be manufactured in, for example, a prismatic type, a pouch type, a coin type, and a cylindrical type, depending on the manufacturing form.

[0059]

[0060] non-aqueous electrolyte

[0061] A non-aqueous electrolyte (140) according to one embodiment of the present invention includes a lithium salt; an organic solvent, and an additive. Here, the organic solvent includes a first organic solvent and a second organic solvent, and the first organic solvent is CFH2CFHCFH2, and the second organic solvent is a cyclic carbonate-based organic solvent.

[0062]

[0063] (1) Lithium salt

[0064] The lithium salt included in the non-aqueous electrolyte (140) of the present invention is commonly used as an electrolyte salt in a lithium secondary battery (100), and is used as a medium for transferring ions.

[0065] The lithium salt used in the present invention is, for example, Li as a cation. + , and the anion is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , AlO2 - , AlO4 - , AlCl4 - , PF6 - , SbF6 - , AsF6 - , B 10 Cl 10 - , BF2C2O4 - , BC4O8 -, PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , C4F9SO3 - , CF3CF2SO3 - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CH3SO3 - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - It may include at least one selected from. For example, the lithium salt may be LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiFSI (lithium bis(fluorosulfonyl) imide, LiN(SO2F)2), LiBETI (lithium bis(perfluoroethanesulfonyl) imide, LiN(SO2CF2CF3)2) and LiTFSI (lithium bis(trifluoromethanesulfonyl) imide, LiN(SO2CF3)2). In one embodiment, the lithium salt may include LiPF6.

[0066] The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film for preventing corrosion on the electrode surface, it may be included in the electrolyte at a concentration of 0.1 M to 3.0 M, for example, a concentration of 0.5 M to 3.0 M, or a concentration of 1.0 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 a lithium secondary battery is sufficient, and the viscosity of the non-aqueous electrolyte (140) is appropriate, so that the electrolyte impregnation property can be improved.

[0067]

[0068] (2) Organic solvent

[0069] (2-1) First organic solvent

[0070] A non-aqueous electrolyte (140) according to one embodiment of the present invention includes CFH2CFHCFH2 as a first organic solvent.

[0071] The above CFH2CFHCFH2 is less likely to self-decompose at high temperatures and high potentials compared to 1,1,1-trifluoropropane or 1,1,2-trifluoropropane due to the fluorine (F) functional group structure uniformly distributed within the structure, and has the effect of stabilizing the cyclic carbonate-based organic solvent by the mechanism of action of further binding Li cations to the cyclic carbonate-based organic solvent. Therefore, the decomposition of the cyclic carbonate-based organic solvent, which is the second organic solvent described below, can be effectively suppressed. Accordingly, a lithium secondary battery including the non-aqueous electrolyte of the present invention including CFH2CFHCFH2 as the first organic solvent can effectively reduce the generation of gases generated by electrolyte side reactions during operation.

[0072]

[0073] The first organic solvent may be included in an amount of about 5% by volume or more, about 10% by volume or more, or about 15% by volume or more, based on the total organic solvent. In addition, the first organic solvent may be included in an amount of about 40% by volume or less, or about 30% by volume or less, based on the total organic solvent. In one embodiment, the first organic solvent may be included in an amount of about 25% by volume or less. When the content of the first organic solvent satisfies the above range, there is an effect of improving the high-temperature durability of the cell while maintaining high ionic conductivity.

[0074]

[0075] (2-2) Second organic solvent

[0076] The non-aqueous electrolyte (140) of the present invention includes a cyclic carbonate-based organic solvent as a second organic solvent. The cyclic carbonate-based organic solvent is a high-viscosity organic solvent with a high dielectric constant, which can easily dissociate lithium salts in the electrolyte, thereby improving the output characteristics of the lithium secondary battery (100). Examples of the cyclic carbonate may include at least one organic solvent selected from ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, and 2,3-pentylene carbonate. In one embodiment, among these, ethylene carbonate (EC) may be used in terms of stable film formation and relatively high ionic conductivity.

[0077]

[0078] The second organic solvent may be included in an amount of about 5% by volume or more or about 10% by volume or more based on the total organic solvent. For example, the second organic solvent may be included in an amount of about 15% by volume or more. In addition, the second organic solvent may be included in an amount of about 40% by volume or less or about 35% by volume or less based on the total organic solvent. For example, the second organic solvent may be included in an amount of about 30% by volume or less. When the content of the second organic solvent satisfies the above range, the cell has an excellent high-temperature durability while maintaining high ionic conductivity.

[0079]

[0080] Meanwhile, the ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the second organic solvent, cyclic carbonate-based organic solvent, may be about 0.16 to 2.0. Within the above range, the viscosity of the organic solvent can be appropriately controlled, and the gas generation reduction effect can be significantly improved.

[0081] For example, the ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the second organic solvent, cyclic carbonate-based organic solvent, may be about 0.16 or more, 0.2 or more, about 0.3 or more, about 0.4 or more, or about 0.6 or more. The ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the second organic solvent, cyclic carbonate-based organic solvent, may be about 2.0 or less, 1.9 or less, about 1.8 or less, about 1.7 or less, about 1.6 or less, about 1.5 or less, or about 1.3 or less. The above numerical ranges can be combined with each other without limitation. For example, the ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the second organic solvent, the cyclic carbonate-based organic solvent, may be about 0.16 to 2.0, about 0.3 to 1.8, about 0.6 to 1.6, or about 0.6 to 1.3. When within the above range, the viscosity of the organic solvent is appropriately secured, and the ionic conductivity of the lithium salt can be improved. In addition, the combination of these organic solvent components can minimize gas generation due to decomposition of the cyclic carbonate-based organic solvent, prevent destruction of the SEI film on the surface of the negative electrode active material, and improve the oxidation stability, chemical stability, and electrochemical stability of the non-aqueous electrolyte.

[0082]

[0083] (2-3) Third organic solvent

[0084] The non-aqueous electrolyte according to one embodiment of the present invention may additionally include a third organic solvent.

[0085] According to one embodiment, the third organic solvent may include a linear carbonate-based organic solvent. The linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate. For example, the linear carbonate-based organic solvent may include at least one selected from dimethyl carbonate, diethyl carbonate (DEC), and ethylmethyl carbonate, or may include at least one of dimethyl carbonate and ethylmethyl carbonate.

[0086]

[0087] When the organic solvent further includes a linear carbonate-based organic solvent as a third organic solvent, the ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the third organic solvent, the linear carbonate-based organic solvent, may be about 0.07 or more, 0.10 or more, 0.16 or more, 0.20 or more, 0.25 or more, 0.30 or more, or about 0.40 or more. The ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the third organic solvent, the linear carbonate-based organic solvent, may be about 6.0 or less, 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, or about 1.5 or less. The above numerical ranges may be combined with each other without limitation. According to one embodiment, the ratio of the volume of the first organic solvent, CFH2CFHCFH2, to the volume of the third organic solvent, the linear carbonate-based organic solvent, may be about 0.07 to 6.0, about 0.10 to 5.0, about 0.20 to 4.0, or about 0.3 to 2.0. When within the above range, it is possible to implement a non-aqueous electrolyte (140) having excellent oxidation stability while appropriately controlling the viscosity of the organic solvent.

[0088]

[0089] In addition, in order to prepare an electrolyte having high ionic conductivity with the third organic solvent, at least one ester organic solvent selected from a linear ester organic solvent and a cyclic ester organic solvent may be additionally included.

[0090] Such linear ester organic solvents may include, for example, at least one organic solvent selected from methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0091] In addition, the cyclic ester organic solvent may include at least one organic solvent selected from γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0092]

[0093] In addition, the non-aqueous electrolyte (140) of the present invention may be used by adding an organic solvent commonly used in the non-aqueous electrolyte (140) as a third organic solvent without limitation, if necessary. For example, at least one organic solvent among an ether-based organic solvent, a glyme-based organic solvent, and a nitrile-based organic solvent may be additionally included.

[0094] As the above ether organic solvent, any one selected from 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 may be used, but is not limited thereto.

[0095] The above glyme-based organic solvent has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents, and is a solvent with less reactivity with metals, and may include at least one selected from dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto.

[0096] The above nitrile-based organic solvent may be at least one selected from acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0097] Meanwhile, the remainder of the organic solvent, excluding the first organic solvent and the second organic solvent, included in the non-aqueous electrolyte (140) of the present invention may be a third organic solvent unless otherwise specified.

[0098]

[0099] (3) Additives

[0100] The above non-aqueous electrolyte (140) may further include an additive along with the above-described lithium salt and organic solvent.

[0101] The above additive may include an additive capable of additionally forming an SEI film within the non-aqueous electrolyte (140) as needed to prevent the non-aqueous electrolyte (140) of a lithium secondary battery (100) from being decomposed and causing cathode collapse in a high-power environment, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and high-temperature battery expansion suppression effects.

[0102] Such additives may include, as representative examples, at least one additive selected from 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, and may include, for example, at least one additive selected from cyclic carbonate compounds, sultone compounds, and sulfate compounds, or may include a cyclic carbonate compound.

[0103] In one embodiment, the cyclic carbonate compound may be vinylene carbonate (VC) or vinylethylene carbonate.

[0104] In one embodiment, the halogen-substituted carbonate compound may include fluoroethylene carbonate.

[0105] The above sultone compound may include at least one compound selected from 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.

[0106] The above sulfate compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0107] The above phosphate compound may include at least one compound selected from 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.

[0108] The above borate compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalatoborate (LiB(C2O4)2, LiBOB).

[0109] The above nitrile compound may include at least one compound selected from succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0110] The benzene compound may include fluorobenzene, the amine compound may include triethanolamine or ethylenediamine, and the silane compound may include tetravinylsilane.

[0111] The above lithium salt compound is a compound different from the lithium salt included in the non-aqueous electrolyte, and may include lithium difluorophosphate (LiDFP), LiPO2F2, or LiBF4.

[0112] The above additive may be at least one selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), propane sultone (PS), ethene sultone, 1,3-propene sultone (PRS), ethylene sulfate, lithium difluoro(bisoxalato)phosphate, and lithium difluorophosphate, and may include vinylene carbonate (VC) according to one embodiment. In addition, when a combination of vinylene carbonate (VC), 1,3-propane sultone (PS), and 1,3-propene sultone (PRS) is additionally included as the above additive, a more robust SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, and gas generation that may be generated due to decomposition of the electrolyte at high temperatures can be suppressed, thereby improving the high-temperature stability of the lithium secondary battery (100) according to one embodiment of the present invention.

[0113]

[0114] Meanwhile, two or more of the above additives may be mixed and used, and may be included in an amount of about 0.1 wt% or more, for example, about 0.2 wt% or more, or about 0.5 wt% or more, and may also be included in an amount of about 10 wt% or less, about 8 wt% or less, or about 5 wt% or less, based on the total weight of the non-aqueous electrolyte. When the content of the additive satisfies the above range, the effect of improving ionic conductivity and cycle characteristics is more excellent.

[0115]

[0116] lithium secondary battery

[0117] According to one embodiment, the present invention provides a lithium secondary battery (100) including the aforementioned non-aqueous electrolyte (140).

[0118] A lithium secondary battery (100) according to the present invention includes a positive electrode (110); a negative electrode (120) facing the positive electrode (110); a separator (130) interposed between the positive electrode (110) and the negative electrode (120); and the non-aqueous electrolyte (140) described above.

[0119] According to one embodiment, the lithium secondary battery may be manufactured by housing an electrode assembly including the positive electrode (110); a negative electrode (120) facing the positive electrode (110); and a separator (130) interposed between the positive electrode (110) and the negative electrode (120) in a battery case (150), and then injecting the non-aqueous electrolyte (140) described above. At this time, as described above, the lithium secondary battery (100) according to one embodiment of the present invention may be manufactured in a prismatic type, a pouch type, a coin type, and a cylindrical type, for example, depending on the manufactured form.

[0120]

[0121] Following the aforementioned non-aqueous electrolyte (140), the positive electrode (110), negative electrode (120), and separator (130) are described below.

[0122]

[0123] (1) Bipolar

[0124] The above positive electrode (110) may include a positive electrode active material.

[0125] The above-mentioned positive electrode active material may include a lithium nickel cobalt manganese oxide having a high nickel content as a positive electrode active material to increase energy density. For example, the lithium nickel cobalt manganese oxide may have a composition represented by the following chemical formula 2.

[0126] [Chemical Formula 2]

[0127] Li x Ni a Co b M 1 d M 2 d O2

[0128] In the above chemical formula 2, the M 1 It can be Mn or a combination of Mn and Al, and it can be a combination of Mn and Al from the viewpoint of strengthening structural stability.

[0129] M 2 It may be at least one selected from Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0130] The above x represents the atomic fraction of lithium in the lithium nickel cobalt manganese oxide, and may be about 0.90≤x≤1.1, or about 0.95≤x≤1.08, or about 1.0≤x≤1.08.

[0131] The above a represents the atomic fraction of nickel among the metal elements excluding lithium in the lithium nickel cobalt manganese oxide, and may be about 0.80≤a<1.0, or about 0.80≤a≤0.95, or about 0.80≤a≤0.90. When the nickel content satisfies the above range, high-capacity characteristics can be realized.

[0132] The above b represents the atomic fraction of cobalt among the metal elements excluding lithium in the lithium nickel cobalt manganese oxide, and is approximately 0. <b<0.2, 약 0<b≤0.15, 또는 약 0.01≤b≤0.10일 수 있다.

[0133] The above c is M among the metal elements excluding lithium in the lithium nickel cobalt manganese oxide. 1 It represents the atomic fraction of , approximately 0 <c<0.2, 0<c≤0.15, 또는 약 0.01≤c≤0.10일 수 있다.

[0134] The above d is M among the metal elements excluding lithium in the lithium nickel cobalt manganese oxide. 2 It represents the atomic fraction of , which can be about 0≤d≤0.1, or about 0≤d≤0.05.

[0135] The positive electrode active material may be included in an amount of about 60 wt% to 99 wt%, or about 70 wt% to 99 wt%, or about 80 wt% to 98 wt%, based on the total weight of solids excluding the solvent in the positive electrode mixture slurry.

[0136]

[0137] The above positive electrode (110) may include a positive electrode current collector; and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. In this case, the positive electrode active material layer may include the above-described positive electrode active material.

[0138] The thickness of the above positive electrode collector may typically have a thickness of about 3 ㎛ to 500 ㎛.

[0139] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0140] Additionally, the positive electrode current collector may have fine irregularities formed on its surface to enhance the bonding strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0141]

[0142] The positive electrode active material layer is disposed on at least one surface of the positive electrode current collector. For example, the positive electrode active material layer may be disposed on one or both surfaces of the positive electrode current collector.

[0143] The above-mentioned positive electrode active material may be included in the positive electrode active material layer at about 80 wt% to about 99 wt%, taking into account sufficient capacity of the positive electrode active material, etc.

[0144]

[0145] The above-described positive electrode active material layer may further include a binder and / or a conductive material together with the above-described positive electrode active material.

[0146] The binder is a component that improves adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the current collector, and examples thereof include a fluororesin binder including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; a polyalcohol binder including polyvinyl alcohol; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; a polyester binder; and a silane binder.

[0147] Typically, the binder may be included in the positive electrode active material layer in an amount of about 0.1 wt% to 20 wt%, for example, about 0.5 wt% to 15 wt%, or about 1 wt% to 10 wt%.

[0148] Next, the conductive material is a component for further improving the conductivity of the positive electrode active material, and is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powder; conductive powder such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. can be used.

[0149] The above-mentioned conductive material may be included in the positive electrode active material layer in an amount of about 1 wt% to 20 wt%, or about 1 wt% to 15 wt%, or about 1 wt% to 10 wt%.

[0150] In one embodiment, the positive electrode can be manufactured by coating a positive electrode slurry comprising a positive electrode active material and optionally a binder, a conductive material, and a solvent for forming a positive electrode slurry on the positive electrode current collector, followed by drying and rolling. Alternatively, the positive electrode can be manufactured by mixing a positive electrode active material and optionally a binder, a conductive material, etc. to manufacture a film, which is then laminated to the positive electrode current collector.

[0151] The solvent for forming the positive electrode slurry may include at least one selected from N-methyl pyrrolidone, ethanol, methanol and isopropyl alcohol, in terms of facilitating dispersion of the positive electrode active material, binder and / or conductive material, and may include N-methyl pyrrolidone according to one embodiment.

[0152] The solvent may be used in an amount that provides an appropriate viscosity when including the positive electrode active material, and optionally a binder and a conductive material. For example, the solvent may be included so that the concentration of the solid content including the positive electrode active material, and optionally a binder and a conductive material, is about 50 wt% to 95 wt%, or about 70 wt% to 95 wt%, or about 70 wt% to 90 wt%.

[0153]

[0154] (2) Cathode

[0155] Next, the cathode (120) will be described.

[0156] The above negative electrode (120) may include a negative electrode active material.

[0157] According to one embodiment, the negative electrode active material may be a carbon-based active material, a silicon-based active material, or a mixture of a carbon-based active material and a silicon-based active material.

[0158] As the above carbon-based active material, various carbon-based active materials used in the art, for example, graphite-based materials such as natural graphite, artificial graphite, and Kish graphite; pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes, soft carbon, hard carbon, etc. can be used. The shape of the carbon-based active material is not particularly limited, and materials of various shapes such as amorphous, plate-like, flaky, spherical, or fibrous can be used.

[0159] According to one embodiment, the carbon-based active material may be either natural graphite or artificial graphite, and both natural graphite and artificial graphite may be used together to increase adhesion to the current collector and suppress delamination of the active material.

[0160] In addition, the silicon-based active material may be, for example, metal silicon (Si), silicon oxide (SiO). x, here 0 <x<2) 실리콘 탄화물(SiC) 및 Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로부터 선택되는 원소이며, Si은 아님)로부터 선택되는 선택된 1종 이상을 포함할 수 있다. 상기 원소 Y로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (dubnium), Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로부터 선택될 수 있다.

[0161] The average particle diameter (D) of the above silicon-based active material 50 ) may be about 1㎛ to 30㎛, or about 2㎛ to 15㎛, in order to reduce side reactions with the electrolyte while ensuring structural stability during charging and discharging.

[0162] In addition, the negative electrode (120) of the present invention may include at least one selected from the carbon-based active material and the silicon-based active material.

[0163] According to one embodiment, the negative electrode (120) of the present invention may include the carbon-based active material and the silicon-based active material.

[0164] At this time, the weight ratio of the silicon-based active material and the carbon-based active material may be about 1:99 to 30:70, or about 3:97 to 15:85. When the mixing ratio of the silicon-based active material and the carbon-based active material satisfies the above range, the capacity characteristics can be improved while the volume expansion of the silicon-based active material is suppressed, thereby ensuring excellent cycle performance.

[0165]

[0166] The above negative electrode (120) may include a negative electrode current collector; and a negative electrode composite layer disposed on at least one surface of the negative electrode current collector. In this case, the negative electrode active material may be included in the negative electrode composite layer.

[0167] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0168] The above negative electrode current collector may typically have a thickness of about 3 μm to 500 μm.

[0169]

[0170] The negative electrode composite layer is disposed on at least one surface of the negative electrode current collector. For example, the negative electrode composite layer may be disposed on one or both surfaces of the negative electrode current collector.

[0171] The above-mentioned negative active material may be included in the negative electrode composite layer at about 60 wt% to 99 wt% in order to sufficiently express the capacity of the secondary battery while minimizing the effect of volume expansion / contraction on the battery.

[0172] The above negative electrode composite layer may further include a binder and / or a conductive material together with the negative electrode active material.

[0173] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector. Examples of such binders include fluororesin binders such as polyvinylidene fluoride (PVDF); rubber binders including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose binders including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol binders including polyvinyl alcohol; polyolefin binders including polyethylene and polypropylene; polyimidazole binders; polyester binders; and silane binders.

[0174] The binder may be included in the negative electrode composite layer in an amount of about 0.1 wt% to 20 wt%, for example, about 0.5 wt% to 15 wt%, or about 1 wt% to 10 wt%.

[0175] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of about 1 wt% to 20 wt% based on the total weight of the solid content in the negative electrode mixture slurry. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include 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 or metal fibers; fluorinated carbon powders; conductive powders such as 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.

[0176] The conductive material may be included in the negative electrode composite layer in an amount of about 1 wt% to 20 wt%, for example, about 1 wt% to 15 wt%, or about 1 wt% to 10 wt%.

[0177] The above negative electrode (120) can be manufactured by coating a negative electrode slurry containing a negative electrode active material and optionally a binder, a conductive material, and a solvent for forming a negative electrode slurry on the negative electrode current collector, followed by drying and rolling. Alternatively, a negative electrode (120) can be manufactured by mixing a negative electrode active material and optionally a binder, a conductive material, etc. to manufacture a film, and then laminating the film on a negative electrode current collector.

[0178] The solvent for forming the negative electrode slurry may include at least one selected from distilled water, N-methyl pyrrolidone, ethanol, methanol and isopropyl alcohol, for example, distilled water, in terms of facilitating dispersion of the negative electrode active material, binder and / or conductive material.

[0179] The solvent may be used in an amount that provides an appropriate viscosity when including the negative electrode active material, and optionally a binder and a conductive material. For example, the solvent may be included so that the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material, is about 50 wt% to 95 wt%, or about 70 wt% to 90 wt%.

[0180]

[0181] (3) Membrane

[0182] As a separator (130) that can be included in the lithium secondary battery (100) of the present invention, a conventional porous polymer film used as a separator in the past, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, can be used alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc., can be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0183]

[0184] There is no particular limitation on the external shape of the lithium secondary battery (100) of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0185]

[0186] Hereinafter, the present invention will be described through examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims.

[0187]

[0188] Examples and Comparative Examples

[0189] Example 1.

[0190] (Manufacturing of non-aqueous electrolyte)

[0191] Ethylene carbonate (EC), CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0192]

[0193] (Secondary battery manufacturing)

[0194] The cathode active material (Li(Ni)) was added to the solvent N-methyl-2-pyrrolidone (NMP). 0.9 Mn 0.03 Co 0.06 Al 0.01 )O2), a conductive agent (carbon black), and a binder (polyvinylidene fluoride) were added in a weight ratio of 97.6:0.8:1.6 to prepare a positive electrode slurry (solid content 60.0 wt%). The positive electrode slurry was applied to a 13.5 μm thick positive electrode current collector (Al thin film) and dried, and then roll pressed to prepare a positive electrode.

[0195] A negative electrode slurry (solid content: 60 wt%) was prepared by adding a negative electrode active material (graphite:SiO = 94:6 weight ratio), a binder (SBR-CMC), and a conductive agent (carbon black) to water as a solvent in a weight ratio of 97.7:0.8:1.5. The negative electrode slurry was applied to a 6 μm thick copper (Cu) thin film as a negative electrode current collector, dried, and then roll pressed to prepare a negative electrode.

[0196] An electrode assembly was manufactured by interposing a porous separator polypropylene between the positive and negative electrodes manufactured above, and then the assembly was placed in a battery case, and the electrolyte for a lithium secondary battery manufactured above was injected to manufacture a lithium secondary battery.

[0197]

[0198] Example 2.

[0199] (Manufacturing of non-aqueous electrolyte)

[0200] Ethylene carbonate (EC), CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:40:30, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0201]

[0202] (Secondary battery manufacturing)

[0203] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0204]

[0205] Example 3.

[0206] (Manufacturing of non-aqueous electrolyte)

[0207] Ethylene carbonate (EC), CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:10:60, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0208]

[0209] (Secondary battery manufacturing)

[0210] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0211]

[0212] Example 4.

[0213] (Manufacturing of non-aqueous electrolyte)

[0214] Ethylene carbonate (EC), CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:60:10, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0215]

[0216] (Secondary battery manufacturing)

[0217] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0218]

[0219] Example 5.

[0220] (Manufacturing of non-aqueous electrolyte)

[0221] Ethylene carbonate (EC), CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:6:65, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0222]

[0223] (Secondary battery manufacturing)

[0224] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0225]

[0226] Comparative Example 1.

[0227] (Manufacturing of non-aqueous electrolyte)

[0228] Ethylene carbonate (EC) and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:70, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0229]

[0230] (Secondary battery manufacturing)

[0231] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0232]

[0233] Comparative Example 2.

[0234] (Manufacturing of non-aqueous electrolyte)

[0235] CFH2CFCFH2 and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0236]

[0237] (Secondary battery manufacturing)

[0238] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0239]

[0240] Comparative Example 3.

[0241] (Manufacturing of non-aqueous electrolyte)

[0242] Ethylene carbonate (EC), 1,1,1-trifluoropropane and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0243]

[0244] (Secondary battery manufacturing)

[0245] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0246]

[0247] Comparative Example 4

[0248] (Manufacturing of non-aqueous electrolyte)

[0249] Ethylene carbonate (EC), 1,1,2-trifluoropropane and LiPF6 was dissolved to 1.0 M in an organic solvent mixed with ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then vinylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0250]

[0251] (Secondary battery manufacturing)

[0252] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries used above was used.

[0253]

[0254] Lithium salt solvent additive type concentration 1 solvent 2 solvent 3 solvent composition ratio (volume ratio) type content Example 1 LiPF 6 1.0 MCFH 2 CCF H 2 EDM C 20:30:50 VC 0.5 Example 2 LiPF 6 1.0 MCFH 2 CCF H 2 EDM C 40:30:30 VC 0.5 Example 3 LiPF 6 1.0 MCFH 2 CCF H 2 EDM C 10:30:60 VC 0.5 Example 4 LiPF 6 1.0 MCFH 2 CCF H 2 EDM C 60:30:10 VC 0.5 Example 5 LiPF 61.0MCFH2CFCFH2ECDMC5:30:65VC0.5Comparative Example 1LiPF61.0M-ECDMC0:30:70VC0.5Comparative Example 2LiPF61.0MCFH2CFCFH2-DMC20:0:80VC0.5Comparative Example 3LiPF61.0M1,1,1-TrifluoropropaneECDMC20:30:50VC0.5Comparative Example 4LiPF61.0M1,1,2-TrifluoropropaneECDMC20:30:50VC0.5

[0255]

[0256] [Experimental Example]

[0257] Experimental Example 1. Evaluation of high-temperature capacity or storage characteristics

[0258] For the lithium secondary batteries manufactured in the examples and comparative examples, an activation (formation) process was performed under the condition of charging at a 0.2C rate for 3 hours, and then charging was performed under constant current / constant voltage conditions (0.05C cut-off) at a 0.33C rate at 25°C to 4.2 V, fully charging to 100% SOC, and storing at a high temperature (60°C) for 16 weeks.

[0259] During the initial charge and discharge, after checking the capacity at room temperature, the battery was charged to SOC 50 based on the discharge capacity, discharged for 10 seconds at a current of 2.5 C, and the resistance was measured based on the difference in voltage drop at this time, which was used as the initial resistance. After 16 weeks of storage at 60°C, the resistance was measured using the same method, which was used as the final resistance, and the resistance increase rate was calculated using the following formula I. The results are shown in Table 2 below.

[0260] [Formula I]

[0261] Resistance increase rate (%) = (final resistance - initial resistance) / (initial resistance) × 100

[0262]

[0263] Experimental Example 2. Evaluation of High-Temperature Gas Generation

[0264] The lithium secondary batteries manufactured in the examples and comparative examples were subjected to an activation (formation) process under the condition of charging at a 0.2C rate for 3 hours, and then charged at a constant current / constant voltage condition (0.05C cut-off) at a 0.33C rate at 25°C to 4.2 V to fully charge to 100% SOC, and stored at a high temperature (60°C) for 16 weeks. Thereafter, the amount of gas generated was analyzed, and the relative value for the amount of gas generated by the non-aqueous electrolyte of Comparative Example 1 was calculated using the following Equation II, and the results are shown in Table 2 below.

[0265] [Formula II]

[0266] Gas generation amount (%) = {Gas generation amount / Gas generation amount of Comparative Example 1} × 100

[0267] Resistance Increase Rate (%) Gas Generation Amount (%) Example 13.2 18 5.88 Example 21.2 28 1.84 Example 36.9 6 9 2.51 Example 4 16.1 19 4.81 Example 5 19.5 5 9 5.39 Comparative Example 1 36.6 6 100 Comparative Example 2 68.7 9 114.7 Comparative Example 3 60.4 4 103.75 Comparative Example 4 48.6 9 103.17

[0268]

[0269] Referring to Table 2 above, it can be confirmed that in the case of the lithium secondary batteries of Examples 1 to 5, the rate of increase in resistance at high temperatures is significantly reduced and the amount of gas generated is significantly reduced compared to the lithium secondary batteries of Comparative Examples 1 to 4.

[0270] FIG. 2 is a drawing for explaining an automobile (300) including a battery pack (200) composed of the lithium secondary battery (100) of FIG. 1.

[0271] Referring to FIG. 2, a vehicle (300) according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack (200) composed of a lithium secondary battery (100) according to one embodiment of the present invention. The vehicle (300) includes a four-wheeled vehicle and a two-wheeled vehicle. The vehicle (300) operates by receiving power from the battery pack (200) according to one embodiment of the present invention.

[0272]

[0273] Although the present disclosure has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the various embodiments of the present disclosure may be made without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims

1. A non-aqueous electrolyte comprising a lithium salt, an organic solvent and an additive, The above organic solvent includes a first organic solvent and a second organic solvent, The above first organic solvent is CFH2CFHCFH2, The above second organic solvent is a non-aqueous electrolyte which is a cyclic carbonate-based organic solvent.

2. In claim 1, A non-aqueous electrolyte in which the first organic solvent is included in an amount of 5 to 40 volume% based on the total volume of the organic solvent.

3. In claim 1, A non-aqueous electrolyte in which the second organic solvent is included in an amount of 5 to 40 volume% based on the total organic solvent.

4. In claim 1, The above cyclic carbonate-based organic solvent is a non-aqueous electrolyte which is ethylene carbonate or propylene carbonate.

5. In claim 1, The above organic solvent further comprises a third organic solvent, The third organic solvent is a non-aqueous electrolyte that is a linear carbonate-based organic solvent.

6. In claim 5, A non-aqueous electrolyte comprising at least one linear carbonate-based organic solvent selected from dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate.

7. In claim 1, The above lithium salt is a non-aqueous electrolyte containing LiPF6.

8. In claim 1, The above additive is a non-aqueous electrolyte selected from at least one of a cyclic carbonate compound, a halogen-substituted carbonate compound, a sultone compound, a sulfate compound, a phosphate compound, a borate compound, a nitrile compound, a benzene compound, an amine compound, a silane compound, and a lithium salt compound.

9. In claim 8, The above additive is a non-aqueous electrolyte further comprising a combination of vinylene carbonate (VC), 1,3-propane sultone (PS) or 1,3-propene sultone (PRS).

10. Bipolar; A cathode opposite to the anode; A separator interposed between the positive electrode and the negative electrode; and A lithium secondary battery comprising a non-aqueous electrolyte according to claim 1.

11. In claim 10, The above positive electrode is a lithium secondary battery containing lithium nickel cobalt manganese oxide as a positive electrode active material.

12. In claim 10, The above negative electrode is SiO as a negative electrode active material. x (0 <x<2) 또는 SiC를 포함하는 리튬 이차 전지.

13. Containing lithium salt, organic solvent and additives, The above organic solvent includes a first organic solvent and a second organic solvent, The first organic solvent used above is CFH2CFHCFH2, A method for producing a non-aqueous electrolyte using a cyclic carbonate-based organic solvent as the second organic solvent.

14. In claim 13, A method for producing a non-aqueous electrolyte, wherein the first organic solvent is included in an amount of 5 to 40 volume% relative to the total organic solvent.

15. In claim 13, A method for producing a non-aqueous electrolyte, wherein the second organic solvent is included in an amount of 5 to 40 volume% based on the total organic solvent.

16. In claim 13, A method for producing a non-aqueous electrolyte using ethylene carbonate or propylene carbonate as the above cyclic carbonate-based organic solvent.

17. In claim 13, The above organic solvent further comprises a third organic solvent, A method for producing a non-aqueous electrolyte using a linear carbonate-based organic solvent as the third organic solvent.

18. In claim 17, A method for producing a non-aqueous electrolyte, wherein the linear carbonate-based organic solvent comprises at least one selected from dimethyl carbonate, diethyl carbonate, and ethylmethyl carbonate.

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