Non-aqueous electrolyte and lithium secondary battery comprising the same

Abstract

The present application provides a nonaqueous electrolyte and a lithium secondary battery comprising the same. The nonaqueous electrolyte of the present application comprises a lithium salt, an organic solvent, and an additive. The organic solvent comprises a first organic solvent and a second organic solvent, the first organic solvent can be CFH2CFHCFH2, and the second organic solvent can be a cyclic carbonate-based organic solvent.

Description

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Korean Patent Application No. 10-2024-0057211 filed on April 29, 2024, and Korean Patent Application No. 10-2025-0055788 filed on April 28, 2025, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] This invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the non-aqueous electrolyte. Background Technology

[0004] Recently, as the application fields of lithium secondary batteries have expanded to a wide range of technologies, including not only the power supply of electronic equipment such as electrical, electronic, communication and computer devices, but also the energy storage of large-area devices such as vehicles and energy storage devices, the demand for secondary batteries with high capacity, high output and high stability is continuing to grow.

[0005] For example, as lithium-ion batteries develop towards higher capacity and higher power, the probability of abnormal temperature rise during charging and discharging increases. This can lead to so-called thermal runaway, a phenomenon where flames erupt at high temperatures, and once thermal runaway occurs, the flames may be difficult to extinguish. Therefore, safety is considered one of the most important issues to be addressed in high-capacity, high-output lithium-ion batteries. Summary of the Invention

[0006] Technical issues

[0007] This invention provides a non-aqueous electrolyte for lithium secondary batteries that can suppress the decomposition of the non-aqueous electrolyte during operation and / or high-temperature storage, thereby reducing gas generation.

[0008] The lithium secondary battery of the present invention, which incorporates the non-aqueous electrolyte, provides improved overall performance due to improved high-temperature cycling and high-temperature storage characteristics.

[0009] Technical solution

[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 being CFH2CFHCFH2 and the second organic solvent being a cyclic carbonate organic solvent.

[0011] [2] The present invention provides the non-aqueous electrolyte described above [1], wherein the content of the first organic solvent is 5% to 40% by volume relative to the total organic solvent.

[0012] [3] The present invention provides the non-aqueous electrolyte described in [1] or [2] above, wherein the content of the second organic solvent is from 5% to 40% by volume relative to the total organic solvent.

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

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

[0015] [6] The present invention provides at least one of the non-aqueous electrolytes described in [1] to [5] above, wherein the linear carbonate organic solvent is at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

[0016] [7] The present invention provides a non-aqueous electrolyte as described in at least one of [1] to [6] above, wherein the lithium salt comprises LiPF6.

[0017] [8] The present invention provides at least one of the non-aqueous electrolytes described in [1] to [7] above, wherein the additive is at least one selected from cyclic carbonate compounds, halogenated carbonate compounds, sulfonyl lactone compounds, sulfate compounds, phosphoric acid compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds and lithium salt compounds.

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

[0019]

[10] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode opposite to the positive electrode; a separator sandwiched between the positive electrode and the negative electrode; and the non-aqueous electrolyte described above [1].

[0020]

[11] The present invention provides the lithium secondary battery described above

[10] , wherein the positive electrode comprises lithium nickel cobalt manganese oxide as the positive electrode active material.

[0021]

[12] The present invention provides a lithium secondary battery as described in

[10] or

[11] above, wherein the negative electrode comprises SiO x Alternatively, SiC can be used as the negative electrode active material, where 0 <x<2。

[0022]

[13] The present invention provides a method for manufacturing a non-aqueous electrolyte, the 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, wherein the first organic solvent is CFH2CFHCFH2 and the second organic solvent is a cyclic carbonate organic solvent.

[0023]

[14] The present invention provides a method for manufacturing the non-aqueous electrolyte described above

[13] , wherein the content of the first organic solvent is 5% to 40% by volume relative to the total organic solvent.

[0024]

[15] The present invention provides a method for manufacturing the non-aqueous electrolyte described above in

[13] or

[14] , wherein the content of the second organic solvent is from 5% to 40% by volume relative to the total organic solvent.

[0025]

[16] The present invention provides a method for manufacturing a non-aqueous electrolyte as described in at least one of

[13] to

[15] above, wherein the cyclic carbonate organic solvent is ethylene carbonate or propylene carbonate.

[0026]

[17] The present invention provides a method for manufacturing a non-aqueous electrolyte as described in at least one of

[13] to

[16] above, wherein the organic solvent further comprises a third organic solvent, and the third organic solvent is a linear carbonate organic solvent.

[0027]

[18] The present invention provides a method for manufacturing a non-aqueous electrolyte as described in at least one of

[13] to

[17] above, wherein the linear carbonate organic solvent comprises at least one selected from dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.

[0028] Beneficial effects

[0029] The non-aqueous electrolyte of the present invention contains CFH2CFHCFH2 as a co-solvent along with a cyclic carbonate solvent having high lithium transport properties, thus suppressing the decomposition of the cyclic carbonate solvent and the decomposition of CFH2CFHCFH2 itself. This reduces gas generation due to electrolyte side reactions during lithium-ion battery operation. Furthermore, because the non-aqueous electrolyte of the present invention contains CFH2CFHCFH2 as a co-solvent along with the cyclic carbonate solvent, it maintains high ionic conductivity, thereby providing excellent performance in improving output characteristics. Additionally, when using the non-aqueous electrolyte of the present invention, electrolyte side reactions can be suppressed at the negative electrode, thereby inhibiting cell degradation.

[0030] Therefore, the lithium secondary battery of the present invention has the following effect: even if the battery is exposed to high voltage and high temperature for a long time, the overall performance will not deteriorate. Attached Figure Description

[0031] The accompanying drawings illustrate exemplary embodiments of the invention and, together with the detailed description that follows, serve to further understand the technical concept of the invention. Therefore, the invention should not be construed as being limited to the contents described in the drawings.

[0032] Figure 1 The structure of a lithium secondary battery according to one embodiment of the present invention is shown.

[0033] Figure 2 For the purpose of illustrating that it contains by Figure 1 A diagram of a vehicle with a battery pack consisting of lithium secondary batteries.

[0034] In some accompanying drawings, corresponding components are given the same reference numerals. Those skilled in the art will understand that the drawings present elements in a concise and clear manner and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements shown in the drawings may be exaggerated compared to other elements. Furthermore, to avoid interfering with the essence of various embodiments of the invention, elements of known technology that are available or necessary in commercially feasible embodiments may often not be illustrated.

[0035] Symbol Explanation

[0036] 100: Lithium secondary battery

[0037] 110: Positive electrode

[0038] 120: Negative electrode

[0039] 130: Diaphragm

[0040] 140: Non-aqueous electrolyte

[0041] 150: Battery casing

[0042] 200: Battery Pack

[0043] 300: Vehicles Detailed Implementation

[0044] It should be noted that the terms or words used in this specification and claims should not be construed as limited to their conventional or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical idea of ​​the invention, based on the principle that the inventors can appropriately define the concepts of the terms in order to best describe their invention.

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

[0046] Furthermore, in the description of "a to b carbon atoms" in this specification, "a" and "b" refer to the number of carbon atoms contained in a specific functional group. That is, the functional group can contain "a" to "b" carbon atoms. For example, "alkylene with 1 to 5 carbon atoms" refers to alkylene containing 1 to 5 carbon atoms, such as -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, or -CH(CH3)CH2CH2-.

[0047] Furthermore, all alkyl groups in this specification may be substituted or unsubstituted. Unless otherwise defined, “substituted” as used above means that at least one hydrogen atom bonded to a carbon atom is replaced by an element other than hydrogen, such as a halogen atom, a nitro group, or a cyano group.

[0048] In various applications of lithium-ion batteries, such as those used in automotive applications, high capacity, high output, and long lifespan are becoming increasingly important. Typically, linear carbonate organic solvents with low viscosity and low dielectric constant are chosen in combination with cyclic carbonate organic solvents with high dielectric constant but high viscosity as the electrolyte organic solvents used to provide high-output lithium-ion batteries.

[0049] However, linear carbonate organic solvents are easily reduced and decomposed at the negative electrode, producing hydrocarbon gases and potentially causing numerous side reactions. This can lead to performance and stability degradation in lithium-ion batteries containing these solvents.

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

[0051] In view of this, the present invention proposes a technology that can reduce the expansion phenomenon of lithium secondary batteries and improve their stability at high temperatures.

[0052] The invention will be described in more detail below.

[0053] The non-aqueous electrolyte, the lithium secondary battery containing the non-aqueous electrolyte, and / or the method of manufacturing the non-aqueous electrolyte of the present invention may include at least one of the following disclosed configurations, and may include any technically feasible combination of the following configurations.

[0054] See Figure 1 One embodiment of the lithium secondary battery 100 of the present invention includes an electrode assembly, a non-aqueous electrolyte 140, and a battery casing 150. The electrode assembly consists of a positive electrode 110, a negative electrode 120 opposite to the positive electrode 110, and a separator 130 sandwiched between the positive electrode 110 and the negative electrode 120. The battery casing 150 houses the electrode assembly and the non-aqueous electrolyte 140.

[0055] The lithium secondary battery 100 can be manufactured by placing the electrode assembly in the battery casing 150 and then injecting the aforementioned non-aqueous electrolyte 140.

[0056] The lithium secondary battery 100 of one embodiment of the present invention can be manufactured in, for example, prismatic, pouch, coin or cylindrical shapes, depending on the manufacturing form.

[0057] Non-aqueous electrolytes

[0058] In one embodiment of the present invention, the non-aqueous electrolyte 140 comprises a lithium salt, an organic solvent, and an additive. Here, the organic solvent comprises a first organic solvent and a second organic solvent, wherein the first organic solvent is CFH2CFHCFH2, and the second organic solvent is a cyclic carbonate organic solvent.

[0059] (1) Lithium salts

[0060] The lithium salt contained in the non-aqueous electrolyte 140 of the present invention is typically used as an electrolyte salt in a lithium secondary battery 100 and as a medium for transporting ions.

[0061] The lithium salt used in this invention contains, for example, Li. + As a cation and as an anion, it may contain a substance selected from 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 - At least one of the following. Specifically, the lithium salt may include those selected from LiCl, LiBr, LiI, LiBF4, LiClO4, and LiB. 10 Cl 10 The lithium salt may be one or a mixture of two or more of the following: 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). According to one embodiment, the lithium salt may include LiPF6.

[0062] The lithium salt can be appropriately varied within the generally available range, but to obtain the best film-forming effect against electrode surface corrosion, its concentration in the electrolyte can be from 0.1 M to 3.0 M, for example, from 0.5 M to 3.0 M or from 1.0 M to 2.0 M. When the lithium salt concentration meets the above range, the effect of improving the cycle characteristics of the lithium secondary battery when stored at high temperatures is sufficient, and the viscosity of the non-aqueous electrolyte 140 is suitable, thereby improving the electrolyte impregnation.

[0063] (2) Organic solvents

[0064] (2-1) First organic solvent

[0065] In one embodiment of the present invention, the non-aqueous electrolyte 140 contains CFH2CFHCFH2 as a first organic solvent.

[0066] Because the fluorine (F) functional groups are uniformly distributed throughout the structure, CFH2CFHCFH2 is less likely to decompose at high temperatures and potentials compared to 1,1,1-trifluoropropane or 1,1,2-trifluoropropane. Furthermore, through a mechanism that further binds the Li cation to the cyclic carbonate organic solvent, it stabilizes the cyclic carbonate organic solvent. Therefore, the decomposition of the cyclic carbonate organic solvent described below as the second organic solvent can be effectively suppressed. Thus, a lithium secondary battery containing the non-aqueous electrolyte of this invention (containing CFH2CFHCFH2 as the first organic solvent) can effectively reduce gas generation due to side reactions of the electrolyte during operation.

[0067] The content of the first organic solvent relative to all organic solvents can be about 5% by volume or more, or about 10% by volume or more. For example, the content of the first organic solvent can be about 15% by volume or more. Moreover, the content of the first organic solvent relative to all organic solvents can be about 40% by volume or less, or about 30% by volume or less. According to one embodiment, the content of the first organic solvent can be about 25% by volume or less. When the content of the first organic solvent meets the above range, it has the effect of improving the high-temperature durability of the battery cell while maintaining high ionic conductivity.

[0068] (2-2) Second organic solvent

[0069] The non-aqueous electrolyte 140 of the present invention includes a cyclic carbonate organic solvent as a second organic solvent. Cyclic carbonate organic solvents are high-viscosity organic solvents with high dielectric constants, thereby readily dissociating lithium salts in the electrolyte and improving the output characteristics of the lithium secondary battery 100. For example, the cyclic carbonate organic solvent 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-pentaneene carbonate, and 2,3-pentaneene carbonate. According to one embodiment, ethylene carbonate (EC) may be used for stable film formation and to exhibit relatively high ionic conductivity.

[0070] The content of the second organic solvent relative to the total organic solvent can be about 5% by volume or more, or about 10% by volume or more. For example, the content of the second organic solvent can be about 15% by volume or more. Moreover, the content of the second organic solvent relative to the total organic solvent can be about 40% by volume or less, or about 35% by volume or less. For example, the content of the second organic solvent can be about 30% by volume or less. When the content of the second organic solvent meets the above ranges, it has the effect of improving the high-temperature durability of the battery cell while maintaining high ionic conductivity.

[0071] Meanwhile, the volume ratio of the first organic solvent CFH2CFHCFH2 to the volume of the second organic solvent, a cyclic carbonate organic solvent, can be approximately 0.16 to 2.0. Within this range, while appropriately adjusting the viscosity of the organic solvent, the effect of reducing gas generation can be significantly improved.

[0072] For example, the volume ratio of the first organic solvent CFH2CFHCFH2 to the volume ratio of the second organic solvent (cyclic carbonate organic solvent) can be about 0.16 or more, about 0.2 or more, about 0.3 or more, about 0.4 or more, or about 0.6 or more. The volume ratio of the first organic solvent CFH2CFHCFH2 to the volume ratio of the second organic solvent (cyclic carbonate organic solvent) can be about 2.0 or less, about 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. These numerical ranges can be combined without limitation. For example, the volume ratio of the first organic solvent CFH2CFHCFH2 to the volume ratio of the second organic solvent (cyclic carbonate organic solvent) can 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. Within these ranges, the viscosity of the organic solvent is appropriately ensured, and the ionic conductivity of the lithium salt can be improved. Furthermore, the combination of these organic solvent components can minimize gas generation caused by the decomposition of cyclic carbonate organic solvents, prevent or suppress the damage of the SEI film on the surface of the negative electrode active material, and improve the oxidative stability, chemical stability and electrochemical stability of the non-aqueous electrolyte.

[0073] (2-3) Third organic solvent

[0074] The non-aqueous electrolyte in one embodiment of the present invention may further include a third organic solvent.

[0075] According to one embodiment, the third organic solvent may comprise a linear carbonate organic solvent. Furthermore, linear carbonate organic solvents are organic solvents with low viscosity and low dielectric constant. As a representative example, at least one organic solvent selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate may be used. For example, it may comprise at least one selected from dimethyl carbonate, diethyl carbonate (DEC), and ethyl methyl carbonate, or it may comprise at least one of dimethyl carbonate and ethyl methyl carbonate.

[0076] When the organic solvent further comprises a linear carbonate organic solvent as a third organic solvent, the volume ratio of the first organic solvent CFH2CFHCFH2 to the volume of the third organic solvent linear carbonate organic solvent can 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 volume ratio of the first organic solvent CFH2CFHCFH2 to the volume of the third organic solvent linear carbonate organic solvent can 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 can be combined without limitation. According to one embodiment, the volume ratio of the first organic solvent CFH2CFHCFH2 to the volume of the third organic solvent linear carbonate organic solvent can 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. Within the aforementioned range, a non-aqueous electrolyte 140 with excellent oxidative stability can be achieved by appropriately adjusting the viscosity of the organic solvent.

[0077] In addition, in order to prepare an electrolyte with high ionic conductivity using a third organic solvent, it may also contain at least one ester organic solvent selected from linear ester organic solvents and cyclic ester organic solvents.

[0078] Linear ester organic solvents may include at least one organic solvent selected from, for example, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate and butyl propionate.

[0079] In addition, cyclic ester organic solvents may include at least one organic solvent selected from γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone and ε-caprolactone.

[0080] Furthermore, in the non-aqueous electrolyte 140 of the present invention, if necessary, an organic solvent commonly used in non-aqueous electrolytes 140 may be added and used as a third organic solvent without limitation. For example, at least one organic solvent selected from ether organic solvents, glycol ether organic solvents, and nitrile organic solvents may also be included.

[0081] For ether-based organic solvents, any one or a mixture of two or more 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) can be used, but the present invention is not limited thereto.

[0082] Glycol ether organic solvents are solvents with high dielectric constant, low surface tension and low metal reactivity compared with linear carbonate organic solvents. They may contain at least one selected from dimethoxyethane (glycol dimethyl ether, DME), diethoxyethane, diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (Triglyme) and tetraethylene glycol dimethyl ether (TEGDME), but the present invention is not limited thereto.

[0083] Nitrile organic solvents may be selected from at least one of acetonitrile, propionitrile, butyronitrile, valerate, octanoic acid, heptanonitrile, cyclopentaneformitrile, cyclohexaneformitrile, 2-fluorobenzyl nitrile, 4-fluorobenzyl nitrile, difluorobenzyl nitrile, trifluorobenzyl nitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but are not limited thereto.

[0084] Meanwhile, in the organic solvent contained in the non-aqueous electrolyte 140 of the present invention, unless otherwise stated, the remaining portion of the organic solvent other than the first organic solvent and the second organic solvent may contain only the third organic solvent.

[0085] (3) Additives

[0086] The non-aqueous electrolyte 140 may also contain additives along with the lithium salt and organic solvents described above.

[0087] Regarding additives, in order to prevent the non-aqueous electrolyte 140 of the lithium secondary battery 100 from decomposing under high power conditions and causing negative electrode failure, or to further improve the low-temperature high-rate discharge characteristics, high-temperature stability, overcharge protection and high-temperature battery expansion suppression effect, additives that can form an SEI film may be included in the non-aqueous electrolyte 140 if necessary.

[0088] As a representative example, the additive may include at least one additive selected from cyclic carbonate compounds, halogenated carbonate compounds, sulfonyl compounds, sulfate compounds, phosphoric acid compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds and lithium salt compounds, and may include, for example, at least one selected from cyclic carbonate compounds, sulfonyl compounds and sulfate compounds, or may contain cyclic carbonate compounds.

[0089] According to one embodiment, cyclic carbonate compounds may include vinylene carbonate (VC) or vinyl ethylene carbonate.

[0090] According to one embodiment, the halocarbonate compound may include fluoroethylene carbonate (FEC).

[0091] Sulfolactone compounds may include at least one compound selected from 1,3-propanesulfonyl lactone (PS), 1,4-butanesulfonyl lactone, ethylenesulfonyl lactone, 1,3-propenesulfonyl lactone (PRS), 1,4-butenesulfonyl lactone, and 1-methyl-1,3-propenesulfonyl lactone.

[0092] Sulfate compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyltrimethyl sulfate (MTMS).

[0093] Phosphoric acid compounds may include at least one compound selected from lithium difluorodioxazophosphate, lithium difluorophosphate, tri(trimethylsilyl) phosphate, tri(trimethylsilyl) phosphite, tri(2,2,2-trifluoroethyl) phosphate, and tri(2,2,2-trifluoroethyl) phosphite.

[0094] Boric acid compounds may include tetraphenylborate, lithium difluoroborate oxalate (LiODFB), or lithium dioxalate borate (LiB(C2O4)2, LiBOB).

[0095] Nitrile compounds may include at least one compound selected from succinic anion, adiponitrile, acetonitrile, propionitrile, butyric anion, valerate, octanoic anion, heptanoic anion, cyclopentaneformitrile, cyclohexaneformitrile, 2-fluorobenzyl anion, 4-fluorobenzyl anion, difluorobenzyl anion, trifluorobenzyl anion, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0096] Benzene compounds may include fluorobenzene, amine compounds may include triethanolamine or ethylenediamine, and silane compounds may include tetravinylsilane.

[0097] Lithium salts are compounds that are different from lithium salts contained in non-aqueous electrolytes, and can include lithium difluorophosphate (LiDFP), LiPO2F2, or LiBF4.

[0098] The additive may be at least one selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), propane sulpholone (PS), vinyl sulpholone, 1,3-propene sulpholone (PRS), ethylene sulfate, lithium difluorodioxazophosphate, and lithium difluorophosphate, and according to one embodiment, it may include vinylene carbonate (VC). Furthermore, when a combination of vinylene carbonate (VC), 1,3-propane sulpholone (PS), and 1,3-propene sulpholone (PRS) is also included as an additive, a more robust SEI film can be formed on the negative electrode surface during the initial activation process of the secondary battery. Then, gas generation that may occur due to electrolyte decomposition 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.

[0099] Furthermore, two or more of these additives can be used in combination, and their content relative to the total weight of the non-aqueous electrolytes can be more than about 0.1% by weight, for example, more than about 0.2% by weight, or more than about 0.5% by weight, or the content can be less than about 10% by weight, less than about 8% by weight, or less than about 5% by weight. When the content of the above additives meets the above ranges, the effect of improving ion conductivity and cycling characteristics is even more excellent.

[0100] Lithium secondary batteries

[0101] According to one embodiment, the present invention provides a lithium secondary battery 100 comprising the above-described non-aqueous electrolyte 140.

[0102] The lithium secondary battery 100 of the present invention includes: a positive electrode 110; a negative electrode 120 opposite to the positive electrode 110; a separator 130 sandwiched between the positive electrode 110 and the negative electrode 120; and the aforementioned non-aqueous electrolyte 140.

[0103] According to one embodiment, the lithium secondary battery 100 can be manufactured by placing an electrode assembly in a battery casing 150 and then injecting the aforementioned non-aqueous electrolyte 140. The electrode assembly includes: a positive electrode 110; a negative electrode 120 opposite to the positive electrode 110; and a separator 130 sandwiched between the positive electrode 110 and the negative electrode 120. Here, as described above, the lithium secondary battery 100 of one embodiment of the present invention can be manufactured in, for example, a prismatic, pouch, coin, or cylindrical shape, depending on the manufacturing process.

[0104] Following the non-aqueous electrolyte 140 described above, the positive electrode 110, negative electrode 120, and separator 130 will be described below.

[0105] (1) Positive electrode

[0106] The positive electrode 110 may contain positive electrode active materials.

[0107] The positive electrode active material may include lithium nickel cobalt manganese oxides with high nickel content as the positive electrode active material to improve energy density. For example, lithium nickel cobalt manganese oxides may have the composition represented by the following chemical formula 2.

[0108] [Chemical Formula 2]

[0109] Li x Ni a Co b M 1 d M 2 d O2

[0110] In the above chemical formula 2, M 1 It can be Mn or a combination of Mn and Al, or, from the perspective of enhancing structural stability, it can be a combination of Mn and Al.

[0111] M 2 may be at least one selected from Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb.

[0112] The symbol "x" represents the atomic fraction of lithium in the lithium nickel cobalt manganese oxide, and may be about 0.90 ≤ x ≤ 1.1, about 0.95 ≤ x ≤ 1.08, or about 1.0 ≤ x ≤ 1.08.

[0113] The symbol "a" represents the atomic fraction of nickel among the metal elements other than lithium in the lithium nickel cobalt manganese oxide, and may be about 0.80 ≤ a < 1.0, 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 achieved.

[0114] The symbol "b" represents the atomic fraction of cobalt among the metal elements other than lithium in the lithium nickel cobalt manganese oxide, and may be about 0 < b < 0.2, about 0 < b ≤ 0.15, or about 0.01 ≤ b ≤ 0.10.

[0115] The symbol "c" represents the atomic fraction of M 1 among the metal elements other than lithium in the lithium nickel cobalt manganese oxide, and may be about 0 < c < 0.2, 0 < c ≤ 0.15, or about 0.01 ≤ c ≤ 0.10.

[0116] The symbol "d" represents the atomic fraction of M 2 among the metal elements other than lithium in the lithium nickel cobalt manganese oxide, and may be about 0 ≤ d ≤ 0.1 or about 0 ≤ d ≤ 0.05.

[0117] Relative to the total weight of the solids other than the solvent in the positive electrode paste mixture, the content of the positive electrode active material may be about 6 wt% to 99 wt%, 70 wt% to 99 wt%, or about 80 wt% to 98 wt%.

[0118] The positive electrode 110 may include a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector. Here, the positive electrode active material may include the above positive electrode active material.

[0119] The thickness of the positive electrode current collector may generally be a thickness of about 3 μm to 500 μm.

[0120] The positive electrode current collector is not particularly limited as long as it has conductivity and does not cause chemical changes in the corresponding battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel with its surface treated with carbon, nickel, titanium, silver, etc. may be used.

[0121] In addition, the bonding strength of the positive electrode active material can be improved by forming fine irregularities on the surface of the positive electrode current collector. For example, the positive electrode current collector can be used in various forms, such as films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0122] 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.

[0123] Considering the full capacity utilization of the positive electrode active material, the positive electrode active material layer may contain approximately 80% to approximately 99% by weight of the positive electrode active material.

[0124] The positive electrode active material layer may also include an adhesive and / or conductive material together with the aforementioned positive electrode active material.

[0125] Adhesives are components that improve the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Examples include: fluoropolymer adhesives including polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber adhesives including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose adhesives including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyol adhesives including polyvinyl alcohol; polyolefin adhesives including polyethylene and polypropylene; polyimide adhesives; polyester adhesives; and silane adhesives.

[0126] Typically, the binder content in the positive electrode active material layer can be from about 0.1% to 20% by weight, for example from about 0.5% to 15% by weight, or from about 1% to 10% by weight.

[0127] Secondly, conductive materials are components used to further improve the conductivity of the positive electrode active material. There are no particular restrictions, as long as they are conductive and do not cause chemical changes in the corresponding battery. For example, the following can be used: carbon powder, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermally cracked carbon 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 dioxide; and conductive materials, such as polyphenylene derivatives.

[0128] In the positive electrode active material layer, the content of conductive material can be from about 1% to 20% by weight, from about 1% to 15% by weight, or from about 1% to 10% by weight.

[0129] According to one embodiment, a positive electrode can be manufactured by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and rolling. The positive electrode slurry comprises a positive electrode active material, and optionally a binder, a conductive material, and a solvent for forming the positive electrode slurry. Alternatively, a membrane can be prepared by mixing the positive electrode active material with optional binders, conductive materials, etc., and then the membrane can be laminated onto the positive electrode current collector to manufacture a positive electrode.

[0130] In order to facilitate the dispersion of positive electrode active materials, binders and / or conductive materials, the solvent for forming the positive electrode slurry may include at least one selected from N-methylpyrrolidone, ethanol, methanol and isopropanol, and according to one embodiment, may include N-methylpyrrolidone.

[0131] The solvent can be used in an amount that yields a suitable viscosity when the positive electrode active material and optional binders, conductive materials, etc., are included. For example, the solvent content can be such that the concentration of the solids, including the positive electrode active material and optional binders and conductive materials, is about 50% to 95% by weight, about 70% to 95% by weight, or about 70% to 90% by weight.

[0132] (2) Negative electrode

[0133] Next, the negative electrode 120 will be described.

[0134] The negative electrode 120 may contain a negative electrode active material.

[0135] According to one embodiment, for the negative electrode active material, carbon-based active materials, silicon-based active materials, or a mixture of carbon-based and silicon-based active materials can be used.

[0136] For carbon-based active materials, various carbon-based active materials used in this field can be used, such as graphite materials like natural graphite, artificial graphite, and Kish graphite; pyrolytic carbon, mesophase pitch-based carbon fibers, mesophase carbon microspheres, mesophase pitch, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived coke, soft carbon, and hard carbon. There are no particular limitations on the shape of carbon-based active materials; materials with various shapes such as amorphous, plate-like, sheet-like, spherical, or fibrous can be used.

[0137] According to one embodiment, for carbon-based active materials, natural graphite or artificial graphite can be used, or both natural graphite and artificial graphite can be used simultaneously, to enhance adhesion to the current collector and inhibit desorption of the active material.

[0138] In addition, silicon-based anode active materials may include, for example, those selected from metallic silicon (Si) and silicon oxide (SiO2). x, where 0 < x < 2), silicon carbide (SiC), and at least one of Si-Y alloy (Y is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si). The element Y can be selected from 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, and combinations thereof.

[0139] In terms of reducing side reactions with the electrolyte while ensuring structural stability during charge and discharge, the average particle size (D 50 ) of the silicon-based active material can be about 1 µm to 30 µm, or about 2 µm to 15 µm.

[0140] In addition, the negative electrode 120 of the present invention may include at least one selected from carbon-based active materials and silicon-based active materials.

[0141] According to one embodiment, the negative electrode 120 of the present invention may include a carbon-based active material and a silicon-based active material.

[0142] Here, the weight ratio of the silicon-based active material to the carbon-based active material can 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 volume expansion of the silicon-based active material can be suppressed while the capacity characteristics can be improved, thereby ensuring excellent cycle performance.

[0143] The negative electrode 120 may include a negative electrode current collector and a negative electrode composite layer provided on at least one surface of the negative electrode current collector. Here, the negative electrode active material may be included in the negative electrode composite layer.

[0144] The negative electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the corresponding battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum cadmium alloy can be used. Moreover, like the positive electrode current collector, the binding force of the negative electrode active material can also be enhanced by forming fine concavities and convexities on the surface. The negative electrode current collector can be used in various forms, such as films, sheets, foils, meshes, porous bodies, foams, and non-woven fabrics.

[0145] The thickness of the negative electrode current collector is usually about 3 μm to 500 μm.

[0146] 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.

[0147] To fully realize the capacity of the secondary battery while minimizing the impact of volume expansion / contraction on the battery, the content of the negative electrode active material in the negative electrode composite layer can be approximately 60% to 99% by weight.

[0148] The negative electrode composite layer may also include an adhesive and / or conductive material together with the negative electrode active material.

[0149] Adhesives are components that facilitate the bonding between conductive materials, active materials, and current collectors. Examples of such adhesives may include: fluoropolymer adhesives such as polyvinylidene fluoride (PVDF); rubber adhesives including styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, and styrene-isoprene rubber; cellulose adhesives including carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyol adhesives including polyvinyl alcohol; polyolefin adhesives including polyethylene and polypropylene; polyimide adhesives; polyester adhesives; and silane adhesives.

[0150] In the negative electrode composite layer, the content of the binder can be from about 0.1% by weight to 20% by weight, for example from about 0.5% by weight to 15% by weight, or from about 1% by weight to 10% by weight.

[0151] Conductive materials are components used to further improve the conductivity of the negative electrode active material. Their addition amount can range from approximately 1% to 20% by weight relative to the total weight of solids in the negative electrode slurry mixture. There are no specific limitations on the conductive material, as long as it is conductive and does not cause chemical changes in the corresponding battery. Examples of materials that can be used include: carbon powder, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermally cracked carbon black; graphite powder, such as natural graphite, artificial graphite, or graphite with a highly developed crystalline 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 dioxide; and conductive materials, such as polyphenylene derivatives.

[0152] In the negative electrode composite layer, the content of conductive material can be from about 1% to 20% by weight, for example, from about 1% to 15% by weight, or from about 1% to 10% by weight.

[0153] The negative electrode 120 can be manufactured by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and rolling. The negative electrode slurry comprises a negative electrode active material, and optionally a binder, a conductive material, and a solvent for forming the negative electrode slurry. Alternatively, a membrane can be prepared by mixing the negative electrode active material with optional binders, conductive materials, etc., and then the membrane can be laminated onto the negative electrode current collector to manufacture the negative electrode 120.

[0154] In order to promote the dispersion of, for example, negative electrode active materials, binders and / or conductive materials, the solvent for forming the negative electrode slurry may include at least one selected from distilled water, N-methylpyrrolidone, ethanol, methanol and isopropanol, such as distilled water.

[0155] The solvent can be used in an amount that yields a suitable viscosity when the negative electrode active material and optional binders, conductive materials, etc., are included. For example, the solvent content can be such that the concentration of the solids, including the negative electrode active material and optional binders and conductive materials, is about 50% to 95% by weight, or about 70% to 90% by weight.

[0156] (3) Diaphragm

[0157] For the separator 130 included in the lithium secondary battery 100 of the present invention, a conventional porous polymer membrane commonly used as a separator can be employed. For example, a porous polymer membrane made of polyolefin polymers (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 conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc., can be used, but the present invention is not limited thereto. In addition, coated separators containing ceramic components or polymer materials can also be used to ensure heat resistance or mechanical strength, and can optionally be used in a single-layer or multi-layer structure.

[0158] The shape of the lithium secondary battery 100 of the present invention is not particularly limited, but it can be cylindrical, prismatic, pouch-shaped or coin-shaped.

[0159] The present invention will be illustrated below by way of examples. However, the following examples are merely illustrative to aid in understanding the invention and are not intended to limit the scope of the invention. Those skilled in the art will understand that various changes and modifications can be made within the scope of this specification and the technical concept, and these changes and modifications are naturally within the scope of the appended claims.

[0160] Examples and Comparative Examples

[0161] Example 1

[0162] (Manufacturing of non-aqueous electrolytes)

[0163] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then ethylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0164] (Manufacturing of secondary batteries)

[0165] The positive electrode active material (Li(Ni) 0.9 Mn 0.03 Co 0.06 Al 0.01 O2, conductive material (carbon black), and binder (polyvinylidene fluoride) were added to N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 97.6:0.8:1.6 to prepare a positive electrode slurry (solids content: 60.0% by weight). The positive electrode slurry was coated onto a 13.5 μm thick positive current collector (Al film) and dried, and then rolled to manufacture the positive electrode.

[0166] A negative electrode active material (graphite:SiO = 94:6 by weight), a binder (SBR-CMC), and a conductive material (carbon black) were added to water as a solvent in a weight ratio of 97.7:0.8:1.5 to prepare a negative electrode slurry (solids content: 60% by weight). The negative electrode slurry was coated onto a 6 μm thick negative electrode current collector (copper (Cu) film) and dried, followed by roll forming to manufacture the negative electrode.

[0167] A porous polypropylene separator is inserted between the manufactured positive and negative electrodes to produce an electrode assembly. The electrode assembly is then housed in a battery casing and injected with a prepared lithium-ion battery electrolyte to manufacture a lithium-ion secondary battery.

[0168] Example 2

[0169] (Manufacturing of non-aqueous electrolytes)

[0170] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 30:40:30, and then ethylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0171] (Manufacturing of secondary batteries)

[0172] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0173] Example 3

[0174] (Manufacturing of non-aqueous electrolytes)

[0175] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 30:10:60, and then ethylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0176] (Manufacturing of secondary batteries)

[0177] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0178] Example 4

[0179] (Manufacturing of non-aqueous electrolytes)

[0180] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 30:60:10, and then ethylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0181] (Manufacturing of secondary batteries)

[0182] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0183] Example 5

[0184] (Manufacturing of non-aqueous electrolytes)

[0185] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 30:6:65, and then ethylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0186] (Manufacturing of secondary batteries)

[0187] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0188] Comparative Example 1

[0189] (Manufacturing of non-aqueous electrolytes)

[0190] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 30:70, and then ethylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0191] (Manufacturing of secondary batteries)

[0192] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0193] Comparative Example 2

[0194] (Manufacturing of non-aqueous electrolytes)

[0195] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing CFH2CFCFH2 and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then vinylene carbonate (VC) was added as an additive to 0.5% by weight to prepare a non-aqueous electrolyte (see Table 1 below).

[0196] (Manufacturing of secondary batteries)

[0197] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0198] Comparative Example 3

[0199] (Manufacturing of non-aqueous electrolytes)

[0200] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), 1,1,1-trifluoropropane and ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then ethylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0201] (Manufacturing of secondary batteries)

[0202] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0203] Comparative Example 4

[0204] (Manufacturing of non-aqueous electrolytes)

[0205] LiPF6 was dissolved to 1.0 M in an organic solvent obtained by mixing ethylene carbonate (EC), 1,1,2-trifluoropropane and ethyl methyl carbonate (EMC) in a volume ratio of 30:20:50, and then ethylene carbonate (VC) was added as an additive to 0.5 wt% to prepare a non-aqueous electrolyte (see Table 1 below).

[0206] (Manufacturing of secondary batteries)

[0207] The lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte for lithium secondary batteries prepared above was used.

[0208] [Table 1] Composition of non-aqueous electrolytes

[0209] [Experimental Example]

[0210] Experimental Example 1. Evaluation of High-Temperature Capacity or Storage Characteristics

[0211] The lithium secondary batteries manufactured in the examples and comparative examples were activated (formed) by charging at a rate of 0.2 C for 3 hours, and then charged at 25°C at a rate of 0.33 C under constant current / constant voltage conditions to 4.2 V (0.05 C cutoff). The batteries were fully charged to 100% SOC and stored at high temperature (60°C) for 16 weeks.

[0212] During the initial charge and discharge, after confirming the capacity at room temperature, the battery was charged to SOC 50 based on the discharge capacity and then discharged at a current of 2.5 C for 10 seconds. The resistance was measured using the voltage drop at this point and used as the initial resistance. After storage at 60°C for 16 weeks, the resistance was measured using the same method and used as the final resistance. The rate of increase in resistance was then calculated using the following mathematical formula I. The results are shown in Table 2 below.

[0213] [Mathematical Formula I]

[0214] Resistance increase rate (%) = (Final resistance - Initial resistance) / Initial resistance × 100

[0215] Experimental Example 2. Evaluation of High-Temperature Gas Generation

[0216] The lithium secondary batteries manufactured in the Examples and Comparative Examples were activated (formed) by charging at a rate of 0.2 C for 3 hours, and then charged at 25°C under constant current / constant voltage conditions at a rate of 0.33 C to 4.2 V (0.05 C cutoff). The batteries were fully charged to 100% SOC and stored at high temperature (60°C) for 16 weeks. The amount of gas produced was then analyzed, and the amount of gas produced relative to the non-aqueous electrolyte of Comparative Example 1 was calculated using the following mathematical formula II. The results are shown in Table 2 below.

[0217] [Mathematical Expression II]

[0218] Gas production rate (%) = {Gas production rate / Gas production rate of Comparative Example 1} × 100

[0219] [Table 2]

[0220] Referring to Table 2 above, it can be found that compared with the lithium secondary batteries of Comparative Examples 1 to 4, the lithium secondary batteries of Examples 1 to 5 show a significant decrease in the rate of increase in resistance at high temperature and a significant reduction in the amount of gas generated.

[0221] Figure 2 For the purpose of illustrating that it contains by Figure 1 The diagram shows a vehicle 300 consisting of a battery pack 200 made up of a lithium secondary battery 100.

[0222] Reference Figure 2 The vehicle 300 of one embodiment of the present invention may be, for example, an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, and includes a battery pack 200 comprising a lithium secondary battery 100 of one embodiment of the present invention. The vehicle 300 includes four-wheeled motor vehicles and two-wheeled motor vehicles. The vehicle 300 operates when powered by the battery pack 200 of one embodiment of the present invention.

[0223] As can be seen from the foregoing, various embodiments of the present invention have been described for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, the various embodiments disclosed herein are not intended to be limiting, and their true scope and spirit are shown in the appended claims.

Claims

1. A non-aqueous electrolyte comprising a lithium salt, an organic solvent, and additives. in, 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 organic solvent.

2. The non-aqueous electrolyte as described in claim 1, wherein, The content of the first organic solvent is 5% to 40% by volume relative to the total organic solvent.

3. The non-aqueous electrolyte as described in claim 1, wherein, The content of the second organic solvent is 5% to 40% by volume relative to the total organic solvent.

4. The non-aqueous electrolyte as described in claim 1, wherein, The cyclic carbonate organic solvent is ethylene carbonate or propylene carbonate.

5. The non-aqueous electrolyte as described in claim 1, wherein, The organic solvent further comprises a third organic solvent, and The third organic solvent is a linear carbonate organic solvent.

6. The non-aqueous electrolyte as described in claim 5, wherein, The linear carbonate organic solvent is at least one selected from dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

7. The non-aqueous electrolyte as described in claim 1, wherein, The lithium salt comprises LiPF6.

8. The non-aqueous electrolyte as described in claim 1, wherein, The additive is selected from at least one of cyclic carbonate compounds, halogenated carbonate compounds, sulcolepsy compounds, sulfate compounds, phosphoric acid compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

9. The non-aqueous electrolyte as described in claim 8, wherein, The additive also comprises a combination of vinylene carbonate (VC), 1,3-propanesulfonyl lactone (PS), or 1,3-propenesulfonyl lactone (PRS).

10. A lithium secondary battery, comprising: positive electrode; The negative electrode opposite to the positive electrode; The membrane sandwiched between the positive and negative electrodes; and The non-aqueous electrolyte according to claim 1.

11. The lithium secondary battery as described in claim 10, wherein, The positive electrode contains lithium nickel cobalt manganese oxide as the positive electrode active material.

12. The lithium secondary battery as described in claim 10, wherein, The negative electrode contains SiO x Alternatively, SiC can be used as the negative electrode active material, where 0 <x<2。 13. A method for manufacturing a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises a lithium salt, an organic solvent, and additives. in, The organic solvent comprises a first organic solvent and a second organic solvent. The first organic solvent used is CFH2CFHCFH2, and The second organic solvent used is a cyclic carbonate organic solvent.

14. The method of claim 13, wherein, The content of the first organic solvent is 5% to 40% by volume relative to the total organic solvent.

15. The method of claim 13, wherein, The content of the second organic solvent is 5% to 40% by volume relative to the total organic solvent.

16. The method of claim 13, wherein, The cyclic carbonate organic solvent used is ethylene carbonate or propylene carbonate.

17. The method of claim 13, wherein, The organic solvent further comprises a third organic solvent, and The third organic solvent used is a linear carbonate organic solvent.

18. The method of claim 17, wherein, The linear carbonate organic solvent includes at least one selected from dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

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