Nonaqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention relates to a nonaqueous electrolyte comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises a compound represented by chemical formula 1, the additive comprises at least one from among the compound represented by chemical formula 1, ethylene sulfate and 1,3-propane sultone, the compound represented by chemical formula 1 is included in an amount of 0.25-1.60 wt% in the nonaqueous electrolyte, and the total amount of the compound represented by chemical formula 1, ethylene sulfate and 1,3-propane sultone can be 0.25-1.60 wt% on the basis of the total weight of the nonaqueous electrolyte. [Chemical formula 1] In chemical formula 1, R1 is -O-NO2, L1 is a C1-C5 alkyleneoxy group, M is a metal cation or an organic cation, a is the valence of M if M is a metal cation and is 1 if M is an organic cation, and a equals b.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0104253, filed August 5, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery including the same.

[0005] As modern society increasingly relies on electrical energy, the development of large-capacity power storage devices capable of stably supplying power while simultaneously increasing production is gaining traction. Furthermore, the need for high-capacity portable power is increasing as the performance of electronic devices, from small electronic devices like mobile phones to medium- to large-sized ones like electric vehicles, continues to improve. Lithium secondary batteries, with their highest potential, satisfy high-capacity power storage requirements and are therefore utilized in a wide range of applications, from small electronic devices to electric vehicles (EVs) and energy storage systems (ESS).

[0006] The above lithium secondary battery is generally composed of a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte that serves as a medium for transferring lithium ions, and a separator. At this time, carbon-based active materials, silicon-based active materials, lithium transition metal oxides, lithium metal, etc. can be used as the negative electrode active material. In addition, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel-cobalt-manganese composite oxide, and lithium iron phosphate can be used as the positive electrode active material.

[0007] When charging a lithium secondary battery, lithium ions are generated from the positive electrode and stored in the negative electrode in the form of a laminate or alloy, while discharge proceeds in the opposite direction. In theory, the movement of lithium ions to the positive and negative electrodes during charge and discharge of such a lithium secondary battery should be reversible, but in reality, some of the movement of lithium within the lithium secondary battery may be irreversible. Specifically, the medium through which lithium ions can move is the electrolyte. During charging, lithium ions are mostly laminated / alloyed within the negative electrode active material, but some can be reduced together with the organic and inorganic substances that make up the electrolyte to form nano-sized organic-inorganic complexes on the surface of the negative electrode material. This is an irreversible and permanent loss of lithium ions provided by the positive electrode, and the organic-inorganic film formed in this way is called a solid electrolyte interface layer (SEI layer). Meanwhile, a solid-electrolyte interface layer can be formed on the surface of the positive electrode active material through an oxidation reaction of a substance that makes up the electrolyte. When the above solid electrolyte interfacial layer is formed, irreversible lithium ion loss is reduced, and the operating potential of the electrolyte is broadly secured, enabling smooth, reversible movement of lithium ions between the positive and negative electrodes. Since this solid electrolyte interfacial layer can also contribute to lowering the energy barrier required for lithium ion charge transfer to the negative or positive electrode depending on the internal components, the appropriate design of the solid-electrolyte interfacial layer has become a research topic for improving the performance of lithium secondary batteries.

[0008] Specifically, the life characteristics and durability of a lithium secondary battery can be determined depending on the stability of the solid-electrolyte interfacial layer. For example, as a lithium secondary battery undergoes charge and discharge, the instability of the initially formed solid-electrolyte interfacial layer can cause additional lithium ion reduction on the surface of the anode material, resulting in the formation of a thicker film than the initially formed solid-electrolyte interfacial layer. The loss of additional lithium ions can also cause an additional interfacial layer thicker than the initially formed solid-electrolyte interfacial layer on the surface of the cathode material, or structural degradation of the cathode material can occur. This can be one of the causes of increased resistance of a lithium secondary battery. When a lithium secondary battery is exposed to high temperatures, the materials that make up the electrolyte decompose, and the side reactions generated as a result can deteriorate the performance of the electrolyte, and the resistance of the lithium secondary battery can increase. As lithium secondary batteries are exposed to high temperatures and repeatedly charged and discharged, the resistance increases, which can cause the positive and negative electrodes to be driven at higher or lower voltages than those in their initial lifespan. This accelerates electrolyte oxidation and reduction reactions at the positive and negative electrodes, which can deteriorate the performance of the lithium secondary battery. Additionally, the instability of the solid-electrolyte interface can cause continuous electrolyte oxidation and reduction reactions, which can generate gases inside the lithium secondary battery. Therefore, enhancing the stability of the solid-electrolyte interface is an important task in order to ensure stable operation of lithium secondary batteries and ensure battery performance such as long life, high-temperature durability, and reduced gas generation.

[0009] [Prior Art Literature]

[0010] [Patent Document]

[0011] Korean Patent Publication No. 10-2377944

[0012] The present invention is intended to solve the above problems, and provides a non-aqueous electrolyte that increases the stability of the solid-electrolyte interface layer formed on the negative electrode and the positive electrode, increases the structural stability of the positive electrode by suppressing lithium loss of the positive electrode, and secures excellent durability and stability at low, room, and high temperatures by including a component having low resistance.

[0013] In addition, the present invention provides a lithium secondary battery having improved overall performance by including the non-aqueous electrolyte, thereby improving low-temperature life, low-temperature output, high-speed charging, room-temperature life, high-temperature storage characteristics, and high-temperature life characteristics.

[0014] [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt; an organic solvent; and an additive, wherein the additive comprises a compound represented by the following chemical formula 1, and the additive comprises at least one of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone, and the compound represented by the chemical formula 1 is contained in the non-aqueous electrolyte in an amount of 0.25 wt% to 1.60 wt%, and the total content of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone is 0.25 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte.

[0015] [Chemical Formula 1]

[0016]

[0017] In the above chemical formula 1, R1 is -O-NO2, L1 is an alkyleneoxy group having 1 to 5 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, and is 1 when M is an organic cation, and a=b.

[0018] [2] The present invention provides a non-aqueous electrolyte in the above [1], wherein M is a metal cation, and M is one selected from the group consisting of Li, K, Ca, Mg, and Cs.

[0019] [3] The present invention provides a non-aqueous electrolyte in at least one of the above [1] and [2], wherein M is an organic cation, and M is any one selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6.

[0020] [Chemical Formula M-1]

[0021]

[0022] In the above chemical formula M-1, X M1 Silver -N(R M15 )- or -S-, and R M11 , R M12 , R M13 , R M14 and R M15 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0023] [Chemical Formula M-2]

[0024]

[0025] In the above chemical formula M-2, X M2 Silver -N(R M25 )- or -S-, and R M21 , R M22 , R M23 , R M24 and R M25are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0026] [Chemical Formula M-3]

[0027]

[0028] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0029] [Chemical Formula M-4]

[0030]

[0031] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M41 , R M42 , R M43 and R M44 At least two of these can be combined with each other to form an aliphatic hydrocarbon ring.

[0032] [Chemical Formula M-5]

[0033]

[0034] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M51 , R M52 , R M53 and R M54 At least two of these can be combined with each other to form an aliphatic hydrocarbon ring.

[0035] [Chemical Formula M-6]

[0036]

[0037] In the above chemical formula M-6, R M61 , R M62 and R M63 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M61 , R M62 and R M63 At least two of these can be combined with each other to form an aliphatic hydrocarbon ring.

[0038] [4] The present invention provides a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-A, wherein the compound represented by the chemical formula 1 in at least one of the above [1] to [3] is a compound represented by the following chemical formula 1-A.

[0039] [Chemical Formula 1-A]

[0040]

[0041] In the above chemical formula 1-A, each of M, a, b and R1 is as defined in the above chemical formula 1.

[0042] [5] The present invention provides a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-A-1, wherein the compound represented by the chemical formula 1 in at least one of the above [1] to [4] is:

[0043] [Chemical Formula 1-A-1]

[0044]

[0045] In the above chemical formula 1-A-1, each of M, a, and b is as defined in the above chemical formula 1.

[0046] [6] The present invention provides a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-a-1 in at least one of the above [1] to [5], wherein the compound represented by the chemical formula 1 in claim 1 is a compound represented by the following chemical formula 1-a-1.

[0047] [Chemical formula 1-a-1]

[0048]

[0049] [7] The present invention provides a non-aqueous electrolyte in which the total content of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone in at least one of the above [1] to [6] is 0.75 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte.

[0050] [8] The present invention provides a non-aqueous electrolyte, wherein in one or more of the above [1] to [7], the additive further includes at least one selected from the group consisting of a cyclic carbonate compound, a nitrile compound, a benzene compound, a lithium salt compound, an amine compound, and a silane compound.

[0051] [9] The present invention provides a non-aqueous electrolyte comprising a carbonate-based organic solvent in at least one of the above [1] to [8].

[0052]

[0010] The present invention provides a non-aqueous electrolyte comprising at least one of the above [1] to [9], wherein the carbonate-based organic solvent comprises a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[0053]

[0011] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the negative electrode and the positive electrode; and a non-aqueous electrolyte according to at least one of [1] to

[0010] .

[0054]

[0012] The present invention provides a lithium secondary battery according to the above

[0011] , wherein the negative electrode includes a negative electrode active material, and the negative electrode active material includes at least one selected from a carbon-based active material and a silicon-based active material.

[0055]

[0013] The present invention provides a lithium secondary battery according to at least one of the above

[0011] and

[0012] , wherein the negative electrode includes a negative electrode active material, and the negative electrode active material includes at least one selected from a carbon-based active material and a silicon-based active material.

[0056] The non-aqueous electrolyte according to the present invention comprises an additive, wherein the additive comprises a salt-form compound containing an organosulfonyl group and nitrogen and oxygen (a compound represented by Chemical Formula 1) in a specific content range. In addition, the additive may optionally include ethylene sulfate and / or 1,3-propane sultone together with the compound represented by Chemical Formula 1, and the content range of these is characterized in that it is controlled within a specific range. When within the above range, a film having strong durability and capable of reducing resistance can be formed on the surfaces of positive and negative electrodes. Therefore, when the non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, it can exhibit excellent life performance and storage performance even under conditions such as high temperature and high voltage, and at the same time, output performance at low temperatures can be improved.

[0057] Figure 1 shows the XIC results for the compound represented by chemical formula 1-a-1.

[0058] Figure 2 is an MS spectrum for a compound represented by chemical formula 1-a-1.

[0059] Figure 3 shows the results of MS / MS analysis (Tandem MS, dual mass spectrometry) for the compound represented by chemical formula 1-a-1.

[0060] Figure 4 is a ¹H-NMR spectrum of a preparation solution of a compound represented by chemical formula 1-a-1.

[0061] Figure 5 is a graph showing the cycle capacity retention rate evaluation of lithium secondary batteries of examples and comparative examples.

[0062] The terms and words used in this specification and claims are only used to describe exemplary embodiments, and should not be construed as limited to their usual or dictionary meanings, and should be construed as meanings and concepts that are consistent with the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to describe his or her own invention in the best way.

[0063] For example, in this specification, terms such as “include,” “have,” or “have” should be understood to specify the presence of a feature, number, step, component, or combination thereof, but not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0064] 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(CH2)CH-, -CH2CH2CH2CH2CH2-, and -CH(CH2)CH2CH2-.

[0065] In addition, in the present specification, the term "alkylene group" means a functional group in the form of a branched or unbranched aliphatic hydrocarbon group or a form in which one hydrogen atom is missing from the carbon atoms located at both ends of the aliphatic hydrocarbon group. In one embodiment, the alkylene group may be substituted or unsubstituted. The alkylene group includes, but is not limited to, a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, a tert-butylene group, a pentylene group, a 3-pentylene group, and the like, and each of these may be optionally substituted in other embodiments.

[0066] Additionally, in this specification, unless otherwise defined, “substitution” means that at least one hydrogen bonded to carbon is replaced with another element such as fluorine.

[0067] Additionally, in this specification, “*” means a bonding site in a chemical formula unless otherwise defined.

[0068]

[0069] Hereinafter, the present invention will be described in more detail.

[0070]

[0071] non-aqueous electrolyte

[0072] The present invention relates to a non-aqueous electrolyte, and more specifically, to a non-aqueous electrolyte for a lithium secondary battery.

[0073] Specifically, the non-aqueous electrolyte of the present invention comprises a lithium salt; an organic solvent; and an additive; wherein the additive comprises a compound represented by the following chemical formula 1, and the additive comprises at least one of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone, and the compound represented by the chemical formula 1 is contained in the non-aqueous electrolyte in an amount of 0.25 wt% to 1.60 wt%, and the total content of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone is 0.25 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte.

[0074] [Chemical Formula 1]

[0075]

[0076] In the above chemical formula 1, R1 is -O-NO2, L1 is an alkyleneoxy group having 1 to 5 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, and is 1 when M is an organic cation, and a=b.

[0077] The non-aqueous electrolyte according to the present invention comprises an additive, wherein the additive comprises a salt-form compound containing an organosulfonyl group and nitrogen and oxygen (a compound represented by Chemical Formula 1) in a specific content range. In addition, the additive may optionally include ethylene sulfate and / or 1,3-propane sultone together with the compound represented by Chemical Formula 1, and the content range of these is characterized in that it is controlled within a specific range. When within the above range, a film having strong durability and capable of reducing resistance can be formed on the surfaces of positive and negative electrodes. Therefore, when the non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, it can exhibit excellent life performance and storage performance even under conditions such as high temperature and high voltage, and at the same time, output performance at low temperatures can be improved.

[0078]

[0079] 1) Lithium salt

[0080] As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation. For example, the lithium salt may be 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 the group consisting of .

[0081] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO2, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 , LiBOB (LiB(C2O4)2), LiCF3SO3, LiFSI (LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI (LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB (LiB(C2O4)2), LiCF3SO3, LiTFSI (LiN(SO2CF3)2), LiFSI ((LiN(SO2F)2), and LiBETI (LiN(SO2CF2CF3)2).

[0082] The lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, specifically at a concentration of 0.8 M to 4 M, and more specifically at a concentration of 0.8 M to 2.5 M. When the concentration of the lithium salt satisfies the above range, the lithium ion yield (Li + The output characteristics of the battery can be improved by improving the transference number and the degree of dissociation of lithium ions.

[0083] Alternatively, the lithium salt may be included in the non-aqueous electrolyte as a remainder, excluding, for example, the organic solvent and additives described below.

[0084]

[0085] 2) Organic solvent

[0086] The organic solvent mentioned above is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as decomposition due to oxidation reactions, etc. during the charging and discharging process of the secondary battery can be minimized.

[0087] The organic solvent may be included in the non-aqueous electrolyte as a remainder, excluding, for example, lithium salts and additives.

[0088] Specifically, the organic solvent may include a carbonate-based organic solvent. The carbonate-based organic solvent may specifically include at least one selected from a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, and more specifically, may include a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[0089] More specifically, the cyclic carbonate-based organic solvent is a high-viscosity organic solvent having a high dielectric constant and thus capable of dissociating a lithium salt in the electrolyte well, and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and may include ethylene carbonate (EC) even more specifically.

[0090] In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may specifically include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethylmethyl carbonate (EMC), methylpropyl carbonate (MPC), and ethylpropyl carbonate (EPC), and more specifically, may include at least one selected from the group consisting of ethylmethyl carbonate and dimethyl carbonate, and even more specifically, may include ethylmethyl carbonate and dimethyl carbonate.

[0091] When the above carbonate-based organic solvent includes a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent, the weight ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be 10:90 to 50:50, specifically 15:85 to 45:55, more specifically 15:85 to 40:60, and even more specifically 20:80 to 40:60.

[0092]

[0093] The above organic solvent may further include at least one of an ester organic solvent, an ether organic solvent, a glyme organic solvent, and a nitrile organic solvent, together with the above carbonate organic solvent.

[0094] The above ester organic solvent may include at least one selected from a linear ester organic solvent and a cyclic ester organic solvent. The linear ester organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. In addition, the cyclic ester organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0095] As the above ether solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto.

[0096] The above glyme-based 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 the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto.

[0097] The above nitrile solvent may be at least one selected from the group consisting of 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.

[0098]

[0099] The organic solvent may be comprised solely of the carbonate-based organic solvent. Even if the carbonate-based organic solvent is used solely as the organic solvent, it is preferable in that it facilitates the dissolution of non-aqueous electrolyte components, such as the additives described below, and enables the implementation of lithium salt mobility and appropriate viscosity of the non-aqueous electrolyte.

[0100]

[0101] 3) Additives

[0102] The above additive comprises a compound represented by the following chemical formula 1. In addition, the compound represented by the chemical formula 1 is included in the non-aqueous electrolyte in an amount of 0.25 wt% to 1.60 wt%. The compound represented by the chemical formula 1 is included in an amount of 0.25 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte.

[0103] [Chemical Formula 1]

[0104]

[0105] In the above chemical formula 1, R1 is -O-NO2, L1 is an alkyleneoxy group having 1 to 5 carbon atoms, M is a metal cation or an organic cation, a is the valence of M when M is a metal cation, and is 1 when M is an organic cation, and a=b.

[0106] The compound represented by the above chemical formula 1 can form a film that is durable and reduces resistance on the positive / negative electrode surface by including a salt-type compound containing an organosulfonyl group and nitrogen and oxygen.

[0107] Specifically, the compound represented by the above chemical formula 1 contains an organosulfonyl group in its structure, and thus, when charged and discharged, it is reduced and decomposed before the organic solvent, and a solid-electrolyte interface layer containing lithium sulfide and lithium sulfoxide having excellent ion conductivity is uniformly formed on the surface of the negative electrode, so that it can function as an effective ion transporter, and thus, degradation of the negative and positive electrodes is suppressed, and since the solid-electrolyte interface layer derived from the functional group has excellent durability, deterioration of the solid-electrolyte interface layer and the problem of transition metal elution of the positive electrode resulting therefrom can be prevented. In addition, the compound represented by the above chemical formula 1 included as the additive contains nitrogen as an anionic terminal group in the structure, and can form a solid-electrolyte interface layer containing lithium nitride, lithium nitrate, lithium oxide, etc. on the surface of the negative electrode, which can improve lithium ion diffusion within the solid-electrolyte interface layer, thereby reducing resistance, and has excellent high-temperature durability to minimize reversible lithium ion loss, and can effectively suppress transition metal elution from the positive electrode by preventing side reactions between the electrolyte and the positive electrode.

[0108] In addition, in the case of existing lithium nitrate-based additives (e.g., LiNO3), when introduced as an electrode film component, there is a problem that the resistance increases and the output performance is lowered because the non-uniform solid-electrolyte interface layer growth induces a reduction reaction of the organic solvent. In addition, the lithium nitrate-based additive also has a problem that it does not dissolve well in carbonate-based organic solvents. On the other hand, in the case of the compound represented by Chemical Formula 1 according to the present invention, as a salt-type compound containing an organosulfonyl group and nitrogen, it is possible to form a uniform solid-electrolyte interface layer, suppress the reduction reaction of the organic solvent, form an electrode film with low resistance, and in particular, it is possible to improve the output performance even under low-temperature conditions where the mobility characteristics of lithium ions are a problem.

[0109] In particular, when the compound represented by the above chemical formula 1 is used as an electrolyte additive, uniform formation of a solid-electrolyte interface layer is realized by simultaneously including an organosulfonyl group and nitrogen in a single compound structure. However, if a substance that does not simultaneously include an organosulfonyl group and nitrogen in a single compound, such as lithium nitrate or cyclic sulfur oxide, is used as an electrolyte additive, a solid-electrolyte interface layer in a particle form or a non-uniform form is formed, and thus the effects of preventing reductive decomposition of an organic solvent, forming a low-resistance film, suppressing elution of a transition metal from a positive electrode, and preventing reduction reaction of a transition metal ion cannot be achieved.

[0110] That is, in the case of the compound represented by the above chemical formula 1, it is possible to implement a strong and highly durable electrode film without lowering the mobility characteristics of lithium ions or the output performance. Accordingly, in the case of the non-aqueous electrolyte including the compound represented by the above chemical formula 1, the electrode can be effectively protected in an environment where side reactions of the electrolyte, collapse of the positive electrode, or destruction of the SEI film of the negative electrode are likely to occur, such as at high temperature and high voltage, and accordingly, the life performance and storage performance of the lithium secondary battery, particularly the life performance and storage performance of the lithium secondary battery under high temperature and high voltage, can be significantly improved. That is, the compound represented by the above chemical formula 1 is highly desirable in that it can achieve the effects of improving the output performance; life performance; and storage performance of the lithium secondary battery at the same time.

[0111] The compound represented by the above chemical formula 1 is contained in the non-aqueous electrolyte at 0.25 wt% to 1.60 wt%. If the compound represented by the above chemical formula 1 is contained in the non-aqueous electrolyte at less than 0.25 wt%, it is difficult to sufficiently form an inorganic film including lithium-nitrogen, lithium-oxygen, and lithium-sulfur bonds on the surfaces of the positive and negative electrodes. If the compound represented by the above chemical formula 1 is contained in the non-aqueous electrolyte at more than 1.60 wt%, problems such as side reactions due to additives, decreased capacity, and increased resistance may occur. Therefore, in order to realize the effect according to the application of the compound represented by the above-mentioned chemical formula 1, it should be used in the above-mentioned range, and through this, while minimizing the disadvantages such as side reactions due to additives, capacity reduction, and resistance increase, a solid inorganic film including lithium-nitrogen, lithium-oxygen, and lithium-sulfur bonds is uniformly formed on the surfaces of the positive and negative electrodes, so that it can effectively operate as an ion transporter, effectively suppress the elution of transition metals from the positive electrode, and effectively suppress side reactions between the electrolyte and the electrode, thereby realizing excellent high-temperature durability and low-temperature output performance.

[0112] Specifically, the compound represented by the above chemical formula 1 may be included in the non-aqueous electrolyte at 0.25 wt% or more, 0.28 wt% or more, 0.30 wt% or more, 0.40 wt% or more, 0.50 wt% or more, 0.60 wt% or more, 0.70 wt% or more, 0.80 wt% or more, 0.90 wt% or more, 1.0 wt% or more, 1.20 wt% or more, 1.30 wt% or more, 1.40 wt% or more, or 1.45 wt% or more. The compound represented by the above chemical formula 1 may be included in the non-aqueous electrolyte at 1.60 wt% or less, 1.50 wt% or less, 1.45 wt% or less, 1.40 wt% or less, 1.30 wt% or less, 1.20 wt% or less, 1.10 wt% or less, 1.0 wt% or less, 0.90 wt% or less, 0.80 wt% or less, 0.70 wt% or less, 0.60 wt% or less, 0.50 wt% or less, 0.40 wt% or less, or 0.35 wt% or less. The above ranges may be combined with each other without limitation.

[0113]

[0114] In the above chemical formula 1, M can be a metal cation or an organic cation.

[0115] Specifically, when M is a metal cation, M may be any one selected from the group consisting of Li, K, Ca, Mg, and Cs, and may be, for example, Li.

[0116] In addition, when M is an organic cation (i.e., a cation in the form of an organic compound), M may be any one selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6.

[0117] [Chemical Formula M-1]

[0118]

[0119] In the above chemical formula M-1, X M1 Silver -N(R M15 )- or -S-, and R M11 , R M12, R M13 , R M14 and R M15 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M11 , R M12 , R M13 , R M14 and R M15 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the chemical formula M-1, R M11 , R M12 , R M13 , R M14 and R M15 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, a methoxy group, or an ethoxy group.

[0120] [Chemical Formula M-2]

[0121]

[0122] In the above chemical formula M-2, X M2 Silver -N(R M25 )- or -S-. R M21 , R M22 , R M23 , R M24 and R M25may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 2 to 12 carbon atoms. Specifically, R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, in the chemical formula M-2, R M21 , R M22 , R M23 , R M24 and R M25 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, an ethoxymethyl group, a 2-ethoxyethyl group, a 3-ethoxypropyl group, a methoxy group, or an ethoxy group.

[0123] [Chemical Formula M-3]

[0124]

[0125] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, an ethoxymethyl group, a 2-ethoxyethyl group, a 3-ethoxypropyl group, a methoxy group, or an ethoxy group.

[0126] [Chemical Formula M-4]

[0127]

[0128] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M41 , R M42 , R M43 and R M44 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, an ethoxymethyl group, a 2-ethoxyethyl group, a 3-ethoxypropyl group, a methoxy group, or an ethoxy group. In addition, R M41 , R M42 , R M43 and R M44 At least two of them may be combined with each other to form an aliphatic ring, specifically R M41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and these can be bonded to each other to form an aliphatic hydrocarbon ring.

[0129] [Chemical Formula M-5]

[0130]

[0131] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M51 , R M52 , R M53 and R M54 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, an ethoxymethyl group, a 2-ethoxyethyl group, a 3-ethoxypropyl group, a methoxy group, or an ethoxy group. In addition, R M51 , R M52 , R M53 and R M54 At least two of them may be combined with each other to form an aliphatic ring, specifically R M51 , R M52 , R M53 and R M54At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and these can be bonded to each other to form an aliphatic hydrocarbon ring.

[0132] [Chemical Formula M-6]

[0133]

[0134] In the above chemical formula M-6, R M61 , R M62 and R M63 may independently be hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. Specifically, R M61 , R M62 and R M63 are independently hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 5 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. More specifically, R M61 , R M62 and R M63 may independently be hydrogen, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, an allyl group (*-CH2CH=CH2), a phenyl group, a cyanomethyl group, a 2-cyanoethyl group, a 3-cyanopropyl group, a 4-cyanobutyl group, a methoxymethyl group, a 2-methoxyethyl group, a 3-methoxypropyl group, an ethoxymethyl group, a 2-ethoxyethyl group, a 3-ethoxypropyl group, a methoxy group, or an ethoxy group. In addition, R M61 , R M62 and R M63 At least two of them may be combined with each other to form an aliphatic ring, specifically R M61 , R M62and R M63 At least two of them are alkyl groups having 1 to 5 carbon atoms or alkyl groups having 2 to 3 carbon atoms, and these can be bonded to each other to form an aliphatic hydrocarbon ring.

[0135] At this time, in the chemical formulas M-1 to M-6, the alkoxyalkyl group having 2 to 10 carbon atoms is, for example, R j2 -OR j1 -*(* is the binding site) can be expressed as R j1 and R j2 may be independently an alkyl group having 1 to 5 carbon atoms, and specifically, may be independently a methyl group, an ethyl group, a propyl group, a butyl group, or a pentyl group.

[0136] For example, the compound represented by the above chemical formula M-1 may include at least one selected from the group consisting of compounds represented by the following chemical formulas M-1-1 to M-1-10.

[0137] [Chemical Formula M-1-1]

[0138]

[0139] [Chemical Formula M-1-2]

[0140]

[0141] [Chemical Formula M-1-3]

[0142]

[0143] [Chemical Formula M-1-4]

[0144]

[0145] [Chemical Formula M-1-5]

[0146]

[0147] [Chemical formula M-1-6]

[0148]

[0149] [Chemical Formula M-1-7]

[0150]

[0151] [Chemical formula M-1-8]

[0152]

[0153] [Chemical formula M-1-9]

[0154]

[0155] [Chemical formula M-1-10]

[0156]

[0157] The compound represented by the above chemical formula M-2 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-2-1 to M-2-3.

[0158] [Chemical Formula M-2-1]

[0159]

[0160] [Chemical formula M-2-2]

[0161]

[0162] [Chemical formula M-2-3]

[0163]

[0164] The compound represented by the above chemical formula M-3 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-3-1 to M-3-6.

[0165] [Chemical Formula M-3-1]

[0166]

[0167] [Chemical formula M-3-2]

[0168]

[0169] [Chemical formula M-3-3]

[0170]

[0171] [Chemical formula M-3-4]

[0172]

[0173] [Chemical formula M-3-5]

[0174]

[0175] [Chemical formula M-3-6]

[0176]

[0177] The compound represented by the above chemical formula M-4 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-4-1 to M-4-17.

[0178] [Chemical formula M-4-1]

[0179]

[0180] [Chemical formula M-4-2]

[0181]

[0182] [Chemical formula M-4-3]

[0183]

[0184] [Chemical formula M-4-4]

[0185]

[0186] [Chemical formula M-4-5]

[0187]

[0188] [Chemical formula M-4-6]

[0189]

[0190] [Chemical formula M-4-7]

[0191]

[0192] [Chemical formula M-4-8]

[0193]

[0194] [Chemical formula M-4-9]

[0195]

[0196] [Chemical formula M-4-10]

[0197]

[0198] [Chemical formula M-4-11]

[0199]

[0200] [Chemical formula M-4-12]

[0201]

[0202] [Chemical formula M-4-13]

[0203]

[0204] [Chemical formula M-4-14]

[0205]

[0206] [Chemical formula M-4-15]

[0207]

[0208] [Chemical formula M-4-16]

[0209]

[0210] [Chemical formula M-4-17]

[0211]

[0212] The compound represented by the above chemical formula M-5 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-5-1 to M-5-14.

[0213] [Chemical Formula M-5-1]

[0214]

[0215] [Chemical Formula M-5-2]

[0216]

[0217] [Chemical formula M-5-3]

[0218]

[0219] [Chemical formula M-5-4]

[0220]

[0221] [Chemical formula M-5-5]

[0222]

[0223] [Chemical formula M-5-6]

[0224]

[0225] [Chemical formula M-5-7]

[0226]

[0227] [Chemical formula M-5-8]

[0228]

[0229] [Chemical formula M-5-9]

[0230]

[0231] [Chemical formula M-5-10]

[0232]

[0233] [Chemical Formula M-5-11]

[0234]

[0235] [Chemical formula M-5-12]

[0236]

[0237] [Chemical Formula M-5-13]

[0238]

[0239] [Chemical formula M-5-14]

[0240]

[0241] The compound represented by the above chemical formula M-6 may be at least one selected from the group consisting of compounds represented by the following chemical formulas M-6-1 to M-6-11.

[0242] [Chemical Formula M-6-1]

[0243]

[0244] [Chemical formula M-6-2]

[0245]

[0246] [Chemical formula M-6-3]

[0247]

[0248] [Chemical formula M-6-4]

[0249]

[0250] [Chemical formula M-6-5]

[0251]

[0252] [Chemical formula M-6-6]

[0253]

[0254] [Chemical formula M-6-7]

[0255]

[0256] [Chemical formula M-6-8]

[0257]

[0258] [Chemical formula M-6-9]

[0259]

[0260] [Chemical formula M-6-10]

[0261]

[0262] [Chemical formula M-6-11]

[0263]

[0264] In the above chemical formula 1, when M is a metal cation, a is the valence of M. For example, for Li, which is an alkali metal, a is 1, and for Ca, which is an alkaline earth metal, a is 2. When M is an organic cation, a is 1. In the above chemical formula 1, a=b.

[0265] For example, the compound represented by the above chemical formula 1 may include a compound represented by the following chemical formula 1-1.

[0266] [Chemical Formula 1-1]

[0267]

[0268] In the above chemical formula 1-1, M, a, b and L1 are as defined in the above chemical formula 1.

[0269] In the above chemical formula 1, L1 may be an alkyleneoxy group having 1 to 5 carbon atoms. For example, L1 may be -OR L1 - can be, R L1 may be an alkylene group having 1 to 5 carbon atoms. In this case, L1 is an alkyleneoxy group (e.g., -OR L1 -), oxygen (O) may be bonded to sulfur (S). L1 may be specifically an alkyleneoxy group having 2 to 3 carbon atoms, more specifically an ethyleneoxy group or a propyleneoxy group, and even more specifically an ethyleneoxy group.

[0270]

[0271] Specifically, the compound represented by the above chemical formula 1 may include a compound represented by the following chemical formula 1-A.

[0272] [Chemical Formula 1-A]

[0273]

[0274] In the above chemical formula 1-A, each of M, a, b and R1 is as defined in the above chemical formula 1.

[0275] More specifically, the compound represented by the above chemical formula 1 may include a compound represented by the following chemical formula 1-A-1.

[0276] [Chemical Formula 1-A-1]

[0277]

[0278] In the above chemical formula 1-A-1, each of M, a, and b is as defined in the above chemical formula 1.

[0279]

[0280] More specifically, the compound represented by the above chemical formula 1 may include a compound represented by the following chemical formula 1-a-1.

[0281] [Chemical formula 1-a-1]

[0282]

[0283]

[0284] The compound represented by the above chemical formula 1 can be formed, for example, by reacting a sulfur oxide (e.g., a cyclic sulfur oxide containing a sulfate group (-OS(=O)2-O-) in the ring) with a metal nitrate (e.g., lithium nitrate, lithium nitrite, etc.), but is not particularly limited thereto. This reaction may be performed in advance before producing a non-aqueous electrolyte, or may be performed by introducing the above-described sulfur oxide and metal nitrate into an organic solvent during the process of producing a non-aqueous electrolyte.

[0285] The presence or absence of the compound represented by the above chemical formula 1 is determined by HR-LS / MS (High Resolution Liquid Chromatography-Mass Spectrometry) and / or 1 It can be confirmed through H-NMR (1H-Nuclear Magnetic Resonance Spectroscopy), but is not particularly limited thereto.

[0286]

[0287] In the present invention, the additive includes at least one of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone. That is, the non-aqueous electrolyte according to the present invention may optionally include ethylene sulfate and / or 1,3-propane sultone together with the compound represented by the chemical formula 1 as an additive. Alternatively, the non-aqueous electrolyte according to the present invention may include ethylene sulfate and / or 1,3-propane sultone together with the compound represented by the chemical formula 1 as an additive, or may include only the compound represented by the chemical formula 1. The ethylene sulfate and / or 1,3-propane sultone may be included in the additive as an auxiliary for forming a sulfur (S)-containing SEI film.

[0288] The total content of the compound represented by the above chemical formula 1, ethylene sulfate, and 1,3-propane sultone is 0.25 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte. When the total content of the compound represented by the above chemical formula 1, ethylene sulfate, and 1,3-propane sultone is less than 0.25 wt% based on the total weight of the non-aqueous electrolyte, there is a problem of deterioration in life performance and / or storage performance due to uneven film formation, and there is a concern that resistance may increase. In addition, when the total content of the compound represented by the above chemical formula 1, ethylene sulfate, and 1,3-propane sultone exceeds 1.60 wt% based on the total weight of the non-aqueous electrolyte, there is a concern that the electrode film may become thicker, increasing the resistance of the battery, and may have a negative effect on charge transfer phenomena such as a decrease in output performance, hysteresis, and polarization, and gaseous byproducts may be generated at the portion where the positive and negative electrodes face each other, hindering the diffusion of lithium ions and causing deposition of lithium metal, thereby accelerating irreversible capacity loss, and other problems may occur.

[0289] In the present invention, the total content of the compound represented by the chemical formula 1, ethylene sulfate, and 1,3-propane sultone may mean, for example, when the non-aqueous electrolyte does not contain ethylene sulfate, the total content of the compound represented by the chemical formula 1 and 1,3-propane sultone in the non-aqueous electrolyte; when the non-aqueous electrolyte does not contain 1,3-propane sultone, the total content of the compound represented by the chemical formula 1 and ethylene sulfate in the non-aqueous electrolyte; and when the non-aqueous electrolyte does not contain 1,3-propane sultone and ethylene sulfate, the content of the compound represented by the chemical formula 1 may mean.

[0290] Specifically, the total content of the compound represented by the above chemical formula 1, ethylene sulfate, and 1,3-propane sultone may be 0.75 wt% to 1.60 wt%, 0.8 wt% to 1.5 wt%, or 0.9 wt% to 1.5 wt% based on the total weight of the non-aqueous electrolyte. When it is within the above-mentioned range, it is preferable in that not only the uniformity of the electrode film is improved, but also stable battery performance can be realized through smooth diffusion of lithium ions.

[0291] If the additive includes ethylene sulfate, the ethylene sulfate may be 1 wt% or less, 0.9 wt% or less, 0.85 wt% or less, 0.81 wt% or less, 0.7 wt% or less, 0.6 wt% or less, or 0.1 wt% or less, based on the total weight of the non-aqueous electrolyte. If the additive includes ethylene sulfate, the ethylene sulfate may be greater than 0 wt% based on the total weight of the non-aqueous electrolyte. The additive may not include ethylene sulfate.

[0292] If the additive includes 1,3-propane sultone, the 1,3-propane sultone may be 0.5 wt% or less, 0.3 wt% or less, 0.2 wt% or less, or 0.1 wt% or less, based on the total weight of the non-aqueous electrolyte. If the additive includes 1,3-propane sultone, the 1,3-propane sultone may be greater than 0 wt% based on the total weight of the non-aqueous electrolyte. The additive may not include 1,3-propane sultone.

[0293]

[0294] The above additives may additionally include auxiliary additives in the electrolyte as needed to prevent the electrolyte from decomposing in a high-power environment and causing cathode collapse, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and high-temperature battery expansion suppression effects.

[0295] The above auxiliary additive may include at least one selected from the group consisting of cyclic carbonate compounds, nitrile compounds, benzene compounds, lithium salt compounds, amine compounds, and silane compounds.

[0296] The above cyclic carbonate compound may be at least one selected from vinylene carbonate (VC) and vinylethylene carbonate (VEC).

[0297] The benzene-based compound may be fluorobenzene. The amine-based compound may be at least one selected from triethanolamine and ethylenediamine. The silane-based compound may be at least one selected from tetravinylsilane, tris(trimethylsilyl) phosphate (TMSPa), and tris(trimethylsilyl) phosphite (TMSPi). The lithium salt-based additive may be at least one selected from lithium bis(oxalato)borate (LiBOB), lithium difluorooxalatoborate (LiODFB), and lithium difluorophosphate (LiDFP).

[0298] The above nitrile compound may be at least one selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0299] Specifically, the auxiliary additive may include at least one selected from vinylene carbonate and fluoroethylene carbonate, and specifically may include vinylene carbonate and fluoroethylene carbonate.

[0300] Meanwhile, two or more of the above auxiliary additives may be mixed and used, and may be included in an amount of less than 10 wt%, specifically 0.01 wt% or more and less than 8.0 wt%, more specifically 0.05 wt% to 5.0 wt%, and even more specifically 3 wt% to 5 wt%, based on the total weight of the non-aqueous electrolyte.

[0301]

[0302] In the present invention, in the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging a lithium secondary battery including the non-aqueous electrolyte, a peak may exist at 1.76 V to 2.25 V.

[0303] In the present specification, the "peak" may be defined as the top point of any one peak region existing in a V-dQ / dV graph where the x-axis is a voltage (V) value and the y-axis is a dQ / dV value, specifically, a point having a minimum dQ / dV value in the peak region. More specifically, any one peak region existing in the V-dQ / dV graph may refer to a voltage region where a reduction reaction of a specific component existing in a non-aqueous electrolyte occurs, and it may be understood that the reduction reaction of the specific component starts at the point where the peak region starts (the minimum voltage point of the peak region), the reduction reaction of the specific component occurs to a maximum at the peak point of the peak region, and the reduction reaction of the specific component ends at the point where the peak region ends (the maximum voltage point of the peak region). The area of ​​the peak region may refer to the amount of the reduction reaction of the specific component, and the width of the peak area may refer to the reduction reaction rate of the specific component.

[0304] In the above V - dQ / dV graph, the peak present at 1.76 V to 2.25 V may be derived from a reduction reaction of the compound represented by the above chemical formula 1. In the above V - dQ / dV graph, the peak present at 1.76 V to 2.25 V may be distinguished from a peak present at 1.0 V to 1.75 V derived from a reduction reaction of a compound that does not contain a sulfur-containing functional group in its structure, such as lithium nitrate; and a peak present at 0.7 V to 1.25 V derived from a reduction reaction of a cyclic sulfur oxide, such as ethylene sulfate or 1,3-propanesultone.

[0305] In deriving the above V - dQ / dV graph, the lithium secondary battery may be in a half-cell form. Specifically, the lithium secondary battery includes a positive electrode (or may be indicated as a first electrode), a negative electrode (or may be indicated as a second electrode), and a separator and a non-aqueous electrolyte, and the positive electrode may include lithium metal and the negative electrode may include a negative electrode active material.

[0306] Specifically, the positive electrode may include lithium metal. Specifically, the positive electrode may be made of lithium metal. The positive electrode may be in the form of a sheet.

[0307] In the above negative electrode, the V - dQ / dV graph is intended to evaluate the reduction performance of a non-aqueous electrolyte compared to lithium metal, and therefore there may be no particular limitation on the type of negative electrode active material. Specifically, the negative electrode active material is a material capable of reversibly inserting / de-inserting black lithium ions, and may include at least one selected from the group consisting of a carbon-based active material, a (semi)metal-based active material, and lithium metal, and specifically may include at least one selected from a carbon-based active material and a (semi)metal-based active material, and more specifically, may include a carbon-based active material. The carbon-based active material may specifically include graphite, and the graphite may be artificial graphite or natural graphite. More specifically, the negative electrode may be directly applied to the description of the negative electrode of a lithium secondary battery described below. Specifically, the descriptions of the negative electrode current collector, the negative electrode active material, the negative electrode active material layer, the negative electrode active material, and optionally included additional components such as a binder and a conductive material may be directly applied to the negative electrode.

[0308] In addition to the above description, the components included in the lithium secondary battery for deriving the V - dQ / dV graph may be the same as those described in the lithium secondary battery described in the present invention.

[0309] In deriving the above V - dQ / dV graph, the charging process of the lithium secondary battery being performed may mean an activation process (formation) of the lithium secondary battery. That is, in deriving the above V - dQ / dV graph, the lithium secondary battery used may be a lithium secondary battery in an uncharged state.

[0310] The charging conditions of the above lithium secondary battery are not particularly limited. For example, the lithium secondary battery can be charged in a constant current / constant voltage (CC / CV) mode, and for example, can be charged in a constant current / constant voltage (CC / CV) mode and cut off at 0.05C, 0.05V. When charging the lithium secondary battery, it can be charged at a charging rate of 0.05C to 1C, specifically 0.1C to 0.5C. When charging the lithium secondary battery, the SOC of the lithium secondary battery can be charged up to 40% to 100%, specifically 70% to 100%, and more specifically 100%.

[0311] In the V - dQ / dV graph obtained by differentiating the graph of voltage V and battery capacity Q measured by charging the lithium secondary battery, a peak may exist at 1.76 V to 2.25 V, specifically at 1.8 V to 2.2 V, and more specifically at 2.0 V to 2.1 V.

[0312]

[0313] lithium secondary battery

[0314] In addition, the present invention provides a lithium secondary battery including the aforementioned non-aqueous electrolyte.

[0315] Specifically, a lithium secondary battery according to the present invention may include a positive electrode; a negative electrode facing the positive electrode; a separator interposed between the negative electrode and the positive electrode; and a non-aqueous electrolyte. The non-aqueous electrolyte may be the non-aqueous electrolyte described above.

[0316] The above lithium secondary battery can be manufactured by housing an electrode assembly including the positive electrode; a negative electrode opposite the positive electrode; and a separator interposed between the positive electrode and the negative electrode in a battery case, and then injecting the above-described non-aqueous electrolyte.

[0317]

[0318] Since the non-aqueous electrolyte has been described above, the cathode, anode, and separator will be described below.

[0319]

[0320] (1) Bipolar

[0321] The above positive electrode may include a positive electrode active material.

[0322] The above-mentioned positive electrode active material is a compound capable of reversible intercalation and deintercalation, and is not particularly limited as long as it is a positive electrode active material used in the relevant field, and may specifically include a lithium metal composite oxide. More specifically, the lithium metal composite oxide may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a lithium iron oxide such as LiFe3O4; a lithium iron phosphate such as LiFePO4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3Lithium manganese composite oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein, M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); but is not limited thereto. The positive electrode may be a Li-metal positive electrode.

[0323] More specifically, the positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide, lithium manganese-rich oxide, and lithium iron phosphate. Even more specifically, the positive electrode active material may include lithium iron phosphate.

[0324] The above lithium nickel cobalt manganese oxide can be represented by the following chemical formula P-1.

[0325] [Chemical formula P-1]

[0326] Li 1+x (Ni a Co b Mn c M d )O2

[0327] In the chemical formula P-1, M is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 1+x, a, b, c and d are atomic fractions of independent elements, respectively, 0≤x≤0.2, 0.50≤a<1, 0 <b≤0.25, 0<c≤0.25, 0≤d≤0.1, a+b+c+d=1이다. 바람직하게는, 상기 a, b, c 및 d는 각각 0.70≤a≤0.95, 0.025≤b≤0.20, 0.025≤c≤0.20, 0≤d≤0.05일 수 있다. 또한, 상기 a, b, c 및 d는 각각 0.80≤a≤0.95, 0.025≤b≤0.15, 0.025≤c≤0.15, 0≤d≤0.05일 수 있다. 또한, 상기 a, b, c 및 d는 각각 0.85≤a≤0.90, 0.05≤b≤0.10, 0.05≤c≤0.10, 0≤d≤0.03일 수 있다.

[0328] The above lithium manganese-rich oxide may include a compound represented by the following chemical formula P-2.

[0329] [Chemical Formula P-2]

[0330] Li 1+s [Ni t Co u Mn v M 1 w ]O 2+z

[0331] In the above chemical formula P-2, M 1is at least one selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, and 0.05≤s≤1, 0≤t≤0.5, 0≤u≤0.3, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. Preferably, in the chemical formula B, 0.05≤s≤1.0, 0.1≤t≤0.5, 0≤u≤0.1, 0.5≤v<1.0, 0≤w≤0.2, 0≤z≤1. More preferably, in the chemical formula P-2, 0.10≤s≤0.50, 0.1≤t≤0.5, 0≤u≤0.1, 0.6≤v<1.0, 0≤w≤0.1, 0≤z≤0.50 may be satisfied.

[0332] The above lithium iron phosphate may include a compound represented by the following chemical formula P-3.

[0333] [Chemical Formula P-3]

[0334] Li 1+e Fe 1-g M 2 g (PO 4-f )X f

[0335] In the above chemical formula P-3, M 2 is one or more elements selected from Co, Ni, Mn, Al, Mg, Ti, and V, X is F, S, or N, and 0≤g≤0.5; -0.5≤e≤+0.5; 0≤f≤0.1. The above chemical formula P-3 can be specifically represented as LiFePO4 (g=0, e=0, and f=0).

[0336] The above positive electrode active material may be in the form of particles. Specifically, the average particle diameter (D) of the positive electrode active material 50 ) can be 1㎛ to 30㎛.

[0337] The above positive electrode active material may be included in the positive electrode active material layer in an amount of 70 wt% to 99 wt%, specifically 80 wt% to 98 wt%, in order to improve capacity.

[0338]

[0339] The above positive electrode 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.

[0340] The thickness of the above positive electrode collector may typically be 3 to 500 μm.

[0341] The above-described positive electrode current collector may also form fine irregularities on its surface to enhance the bonding strength of the positive electrode active material. For example, the above-described positive electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0342] The positive electrode active material layer is disposed on at least one surface of the positive electrode current collector. Specifically, the positive electrode active material layer may be disposed on one or both surfaces of the positive electrode current collector.

[0343] The above-mentioned positive electrode active material may be included in the positive electrode active material layer at 80% to 99% by weight in consideration of sufficient capacity of the positive electrode active material, etc.

[0344] 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.

[0345] The above binder is a component that assists in the binding of the active material and the conductive material and the binding to the current collector, and specifically, may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, and preferably may include polyvinylidene fluoride.

[0346] The above binder may be included in the positive electrode active material layer at 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%, in order to sufficiently secure binding force between components such as the positive electrode active material.

[0347] The conductive material may be used to assist and improve conductivity in a secondary battery, and is not particularly limited as long as it has conductivity without causing chemical changes. Specifically, the positive electrode conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably, in terms of improving conductivity, may include carbon nanotubes.

[0348] The conductive material may be included in the positive electrode active material layer in an amount of 1 wt% to 20 wt%, preferably 1.2 wt% to 10 wt%, in order to sufficiently secure electrical conductivity.

[0349] The thickness of the positive electrode active material layer may be 5 µm to 500 µm, preferably 20 µm to 200 µm.

[0350] The positive electrode can be manufactured by coating a positive electrode slurry containing 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, a positive electrode can be manufactured by mixing a positive electrode active material and optionally a binder, a conductive material, etc. to manufacture a film, and then laminating the film on a positive electrode current collector.

[0351] The solvent for forming the positive electrode slurry may include at least one selected from the group consisting of distilled water, N-methyl pyrrolidone, ethanol, methanol and isopropyl alcohol, preferably N-methyl pyrrolidone, in order to facilitate dispersion of the positive electrode active material, binder and / or conductive agent, for example.

[0352]

[0353] (2) Cathode

[0354] Next, let's explain the cathode.

[0355] The above negative electrode may include a negative electrode active material.

[0356] The above negative electrode active material is a material capable of reversibly inserting / de-inserting lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, (semi)metal-based active materials, and lithium metal, and specifically may include at least one selected from the carbon-based active material and the (semi)metal-based active material. More specifically, the negative electrode active material may include at least one selected from the carbon-based active material and the silicon-based active material.

[0357] The above carbon-based active material may include at least one selected from the group consisting of graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include graphite. The graphite may be, for example, at least one of artificial graphite and natural graphite.

[0358] The average particle diameter (D) of the above carbon-based active material 50 ) may be 10㎛ to 30㎛, preferably 15㎛ to 25㎛, in order to ensure structural stability during charging and discharging and reduce side reactions with the electrolyte.

[0359] Specifically, the (semi-)metal-based active material is at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium and at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (semi-)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); lithium vanadium oxide; It may include:

[0360] More specifically, the (semi)metal-based active material may include a silicon-based active material.

[0361] The above silicon-based active material is SiO x It may include at least one selected from the group consisting of compounds represented by (0≤x<2) and silicon-carbon composites. In the case of SiO2, since it does not react with lithium ions and thus cannot store lithium, it is preferable that x is within the above range, and more preferably, the silicon-based active material may be SiO.

[0362] The average particle diameter (D) of the above silicon-based active material 50 ) may be 1㎛ to 30㎛, preferably 2㎛ to 15㎛, in order to reduce side reactions with the electrolyte while ensuring structural stability during charging and discharging.

[0363] Additionally, the negative electrode active material may include at least one selected from the carbon-based active material and the silicon-based active material.

[0364] For example, the negative electrode of the present invention may include the carbon-based active material and the silicon-based active material. At this time, the weight ratio of the silicon-based active material and the carbon-based active material may be 1:99 to 30:70, specifically 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.

[0365]

[0366] The above negative electrode may include a negative electrode current collector; and a negative electrode active material 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 active material layer.

[0367] The above negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or an aluminum-cadmium alloy.

[0368] The above negative electrode current collector may typically have a thickness of 3 to 500 μm.

[0369] The above-described negative electrode current collector may have fine irregularities formed on its surface to enhance the bonding strength of the negative electrode active material. For example, the above-described negative electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0370] The negative electrode active material layer is disposed on at least one surface of the negative electrode current collector. Specifically, the negative electrode active material layer may be disposed on one or both surfaces of the negative electrode current collector.

[0371] The above negative active material may be included in the negative active material layer at 60 wt% to 99 wt% in order to sufficiently express the capacity of the secondary battery.

[0372] The above negative electrode active material layer may further include a conductive material and / or a binder together with the negative electrode active material.

[0373] The above binder can be used to improve the adhesion between the negative electrode active material layer and the negative electrode current collector, or to improve the bonding strength between negative electrode active materials.

[0374] Specifically, the binder can further improve electrode adhesion and provide sufficient resistance to volume expansion / contraction of the negative electrode active material, and is selected from the group consisting of styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR), acrylonitrile butadiene rubber, acrylic rubber, butyl rubber, fluoro rubber, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyacryl amide (PAM), polyvinylidene fluoride, It may include at least one selected from the group consisting of polytetrafluoroethylene, and polyvinylidene fluoride-hexafluoropropylene.

[0375] The above binder may be included in the negative electrode active material layer at 1 wt% to 30 wt%, and when present in the above range, the negative electrode active material can be better bound, thereby minimizing the problem of volume expansion of the active material, and at the same time, when preparing a slurry for forming the negative electrode active material layer, it can facilitate dispersion of the binder and improve the coating property and phase stability of the slurry.

[0376] The conductive material may be used to assist and improve conductivity in a secondary battery, and is not particularly limited as long as it has conductivity without causing chemical changes. Specifically, the conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, paneth black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.

[0377] The conductive material may be included in the negative electrode active material layer at 1 wt% to 20 wt%, and is preferable in that it can form an excellent conductive network while alleviating the increase in resistance due to the binder when included in the above range.

[0378] The thickness of the negative active material layer may be 5 µm to 500 µm, preferably 5 µm to 200 µm.

[0379] The above negative electrode 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, the negative electrode 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 the negative electrode current collector.

[0380] The solvent for forming the negative electrode slurry may include at least one selected from the group consisting of distilled water, N-methyl pyrrolidone, ethanol, methanol and isopropyl alcohol, preferably distilled water, in order to facilitate dispersion of the negative electrode active material, binder and / or conductive material.

[0381]

[0382] (3) Membrane

[0383] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. If it is a separator commonly used in lithium secondary batteries, it can be used without any special restrictions. In particular, it is preferable that it have low resistance to ion movement of a non-aqueous electrolyte and excellent non-aqueous electrolyte wetting ability.

[0384] Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used as the separator. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, or the like may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0385]

[0386] Meanwhile, the external shape of the lithium secondary battery of the present invention is not particularly limited, and may be cylindrical, square, pouch-shaped, or coin-shaped.

[0387] In addition, the lithium secondary battery of the present invention can be usefully used in portable devices such as mobile phones, laptop computers, and digital cameras, and in electric vehicles such as hybrid electric vehicles (HEVs) and energy storage systems (ESS).

[0388]

[0389] Hereinafter, the present invention will be described in detail with examples to specifically illustrate it. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention should not be construed as being limited to the examples described below. These examples are provided to more fully explain the present invention to those of average skill in the art.

[0390]

[0391] Examples and Comparative Examples

[0392] Example 1

[0393] (1) Preparation of a compound represented by chemical formula 1

[0394] Ethylene sulfate and LiNO3 were dissolved in an equivalence ratio of 1.2:1 in ethyl acetate (EA) solvent at a ratio of 10 wt%, and then mixed at room temperature (15-25°C) to carry out a reaction for forming a compound represented by the chemical formula 1-a-1. As a result of the compound forming reaction, the compound represented by the chemical formula 1, which was not dissolved in the ethyl acetate (EA) solvent, was precipitated in the form of a powder. The solution after the reaction was filtered to obtain a powder. Thereafter, the ethyl acetate solvent remaining in the powder was evaporated, thereby obtaining a compound represented by the chemical formula 1-a-1.

[0395]

[0396] The presence of the compound represented by the above chemical formula 1-a-1 was confirmed by HR-LC / MS (High Resolution Liquid Chromatography-Mass Spectrometry) and 1 It was confirmed using the H-NMR (1H-Nuclear Magnetic Resonance Spectroscopy) method.

[0397] First, the compound (powder) represented by the above chemical formula 1-a-1 was added to an organic solvent containing ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate in a volume ratio of 30:50:20, and diluted with acetone D6 solvent to prepare a sample solution. Using the sample solution, HR-LC / MS and 1 H-NMR was measured.

[0398] HR-LC / MS equipment used was an Orbitrap IQ-X Tribrid from ThermoFisher. The measurement conditions were as follows: CapcellPak C18 as the column, acetonitrile and trifluoroacetate (volume ratio 100:0.02) as eluent A, and distilled water and trifluoroacetate (volume ratio 100:0.02) as eluent B. The flow rate was 1 mL / min, the UV detector was 220 nm, and the ionization mode was electrospray ionization (ESI) negative ionization mode. The 1H-NMR equipment used was an Advance Neo from Bruker.

[0399] The presence of a compound represented by chemical formula 1-a-1 was confirmed through FIGS. 1 to 4. Specifically, the XIC (Extracted Ion Chromatogram) for m / z 185.97140 according to FIG. 1 showed a single peak at 1.35 minutes, confirming that a compound represented by chemical formula 1-a-1 existed in the sample and was separated on LC.

[0400] In the MS spectrum according to Figure 2, 185.97140 corresponding to the anion of the compound represented by Chemical Formula 1-a-1 was observed, which is the molecular formula C2H4NO7S of the compound represented by Chemical Formula 1-a-1. - It matched with .

[0401] Additional MS / MS analysis (Tandem MS, dual mass spectrometry) according to Figure 3 detected fragment ions such as m / z 61.98818 (O3N) and 79.95725 (O3S), which match the expected structural decomposition pattern. These results support the existence and structural identity of the compound represented by Chemical Formula 1-a-1.

[0402] The characteristic chemical shifts of 4.76 (t,2) and 4.18 (t,2) observed in the ¹H-NMR spectrum according to FIG. 4 support the existence of a compound represented by the chemical formula 1-a-1.

[0403]

[0404] (2) Preparation of non-aqueous electrolyte

[0405] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then the compound represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) were contained in the non-aqueous electrolyte in amounts of 0.80 wt%, 3.00 wt%, 1.00 wt%, and 0.10 wt%, respectively.

[0406]

[0407] (3) Manufacturing of lithium secondary batteries

[0408] (Polar electrode manufacturing)

[0409] A positive electrode active material slurry (solid content 100 wt%) was prepared by mixing a positive electrode active material (LiFePO4), a conductive agent (carbon nanotube, CNT), and a binder (polytetrafluoroethylene, PTFE) in a weight ratio of 96.0: 0.5: 3.5. The positive electrode active material slurry was applied to a positive electrode current collector (Al thin film) having a thickness of 13 μm and roll pressed to prepare a positive electrode.

[0410] (Cathode manufacturing)

[0411] A negative active material (a mixture of artificial graphite and natural graphite in a weight ratio of 80:20), styrene-butadiene rubber and carboxymethyl cellulose as binders, and carbon black as a conductive material were added to distilled water as a solvent in a weight ratio of 96.7:2.8:0.5 to prepare a negative active material slurry (solid content: 53 wt%). The negative active material slurry was applied to a negative electrode current collector (Cu thin film) having a thickness of 6 μm, dried, and roll pressed to prepare a negative electrode.

[0412]

[0413] Example 2

[0414] (1) Preparation of non-aqueous electrolyte

[0415] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the manufacturing method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (ESa), and 1,3-propanesultone (PS) were added as additives to prepare a non-aqueous electrolyte. Compounds represented by the above chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (ESa), and 1,3-propanesultone (PS) were included in the non-aqueous electrolyte in amounts of 0.30 wt%, 3.00 wt%, 1.00 wt%, 0.80 wt%, and 0.20 wt%, respectively.

[0416]

[0417] (2) Manufacturing of lithium secondary batteries

[0418] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0419]

[0420] Example 3

[0421] (1) Preparation of non-aqueous electrolyte

[0422] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in the non-aqueous electrolyte in amounts of 1.50 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0423]

[0424] (2) Manufacturing of lithium secondary batteries

[0425] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0426]

[0427] Comparative Example 1

[0428] (1) Preparation of non-aqueous electrolyte

[0429] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a 1.0 M concentration in an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS). The non-aqueous electrolyte contained 3.00 wt%, 1.00 wt%, and 0.2 wt% of vinylene carbonate (VC), 1.00 wt%, and 1,3-propane sultone (PS), respectively.

[0430]

[0431] (2) Manufacturing of lithium secondary batteries

[0432] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0433]

[0434] Comparative Example 2

[0435] (1) Preparation of non-aqueous electrolyte

[0436] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding LiNO3, vinylene carbonate (VC), and fluoroethylene carbonate (FEC). The non-aqueous electrolyte contained 0.25 wt%, 3.00 wt%, and 1.00 wt% of LiNO3, vinylene carbonate (VC), and fluoroethylene carbonate (FEC), respectively.

[0437]

[0438] (2) Manufacturing of lithium secondary batteries

[0439] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0440]

[0441] Comparative Example 3

[0442] (1) Preparation of non-aqueous electrolyte

[0443] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC). The non-aqueous electrolyte contained 0.50 wt%, 3.00 wt%, and 1.00 wt% of ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC), respectively.

[0444]

[0445] (2) Manufacturing of lithium secondary batteries

[0446] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0447]

[0448] Comparative Example 4

[0449] (1) Preparation of non-aqueous electrolyte

[0450] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then adding the compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) as additives. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) were included in amounts of 0.20 wt%, 0.40 wt%, 3.00 wt%, 1.00 wt%, and 0.20 wt%, respectively.

[0451]

[0452] (2) Manufacturing of lithium secondary batteries

[0453] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0454]

[0455] Comparative Example 5

[0456] (1) Preparation of non-aqueous electrolyte

[0457] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 1.70 wt%, 0.70 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0458]

[0459] Comparative Example 6

[0460] (1) Preparation of non-aqueous electrolyte

[0461] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 1.40 wt%, 0.30 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0462]

[0463] (2) Manufacturing of lithium secondary batteries

[0464] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0465]

[0466] Comparative Example 7

[0467] (1) Preparation of non-aqueous electrolyte

[0468] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesultone (PS) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesultone (PS) were included in amounts of 1.40 wt%, 0.10 wt%, 3.00 wt%, 1.00 wt%, and 0.20 wt%, respectively.

[0469]

[0470] (2) Manufacturing of lithium secondary batteries

[0471] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0472]

[0473] Comparative Example 8

[0474] (1) Preparation of non-aqueous electrolyte

[0475] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propane sultone (PS) were included in amounts of 0.30 wt%, 3.00 wt%, 1.00 wt%, and 1.50 wt%, respectively.

[0476]

[0477] (2) Manufacturing of lithium secondary batteries

[0478] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0479]

[0480] Comparative Example 9

[0481] (1) Preparation of non-aqueous electrolyte

[0482] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 0.30 wt%, 1.50 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0483]

[0484] (2) Manufacturing of lithium secondary batteries

[0485] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0486]

[0487] Comparative Example 10

[0488] (1) Preparation of non-aqueous electrolyte

[0489] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesultone (PS) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and 1,3-propanesultone (PS) were contained in amounts of 0.70 wt%, 3.00 wt%, 1.00 wt%, and 1.00 wt%, respectively.

[0490]

[0491] (2) Manufacturing of lithium secondary batteries

[0492] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0493]

[0494] Comparative Example 11

[0495] (1) Preparation of non-aqueous electrolyte

[0496] LiPF6 was dissolved to 1.0 M in an organic solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 30:50:20, and then a compound represented by the chemical formula 1-a-1 (prepared by the method according to Example 1), ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were added as additives to prepare a non-aqueous electrolyte. The compound represented by the chemical formula 1-a-1, ethylene sulfate (ESa), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) were included in amounts of 0.70 wt%, 1.00 wt%, 3.00 wt%, and 1.00 wt%, respectively.

[0497]

[0498] (2) Manufacturing of lithium secondary batteries

[0499] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above non-aqueous electrolyte was used.

[0500]

[0501] Additive (% by weight, based on the weight of non-aqueous electrolyte) Total weight of the compound represented by the chemical formula 1-a-1, ESa and PS Chemical formula 1-a-1 ESaLiNO3 VCFECPS Example 10.80--3.00 1.00 0.10 0.90 Example 20.30 0.80-3.00 1.00 0.20 1.30 Example 31.50--3.00 1.00-1.50 Comparative Example 1---3.00 1.00 0.20 Comparative Example 2--0.25 3.00 1.00-0 Comparative Example 3-0.50-3.00 1.00-0.50 Comparative Example 40.20 0.40-3.00 1.00 0.20 0.80 Comparative Example 51.700.70-3.001.00-2.40Comparative example 61.400.30-3.001.00-1.70Comparative example 71.400.10-3.001.000.201.70Comparative example 80.30--3.001.001.501.80Comparative example 90.301.50-3.001.00-1.80Comparative example 100.70--3.001.001.001.70Comparative example 110.701.00-3.001.00-1.70

[0502]

[0503] Experimental Example: High-Temperature Cycle Performance Evaluation

[0504] High-temperature cycle performance evaluation was performed on the lithium secondary batteries of the examples and comparative examples manufactured above.

[0505] Specifically, the lithium secondary batteries of the examples and comparative examples were charged to 3.8 V under constant current / constant voltage (CC / CV) conditions at 45°C and 0.33 C (0.05 C cut-off), and discharged to 2.5 V under constant current (CC) at 0.33 C, which was considered one cycle, and the discharge capacity after one cycle was measured.

[0506] Then, after 300 charge-discharge cycles under the above-mentioned charge-discharge conditions, the capacity retention rate (%) was measured. The capacity retention rate (%) was calculated according to the following equation. The results are shown in Fig. 5 and Table 2.

[0507] Capacity retention rate (%) = (discharge capacity after 300 cycles / discharge capacity after 1 cycle) × 100

[0508]

[0509] Capacity Retention Rate (%, 300th Cycle) Example 1 91.38 Example 2 90.66 Example 3 91.02 Comparative Example 181.39 Comparative Example 284.58 Comparative Example 386.97 Comparative Example 4 87.06 Comparative Example 5 87.79 Comparative Example 6 88.06 Comparative Example 7 87.77 Comparative Example 8 87.69 Comparative Example 9 87.30 Comparative Example 10 87.49 Comparative Example 11 88.53

[0510]

[0511] Referring to Table 2 and FIG. 5 above, it can be confirmed that the lithium secondary batteries of the examples, which include the compound represented by Chemical Formula 1 in the above-described range and have the content ranges of the compound represented by Chemical Formula 1, ethylene sulfate, and 1,3-propane sultone at specific levels, exhibit significantly superior cycle performance compared to the comparative examples.

Claims

1. A non-aqueous electrolyte comprising a lithium salt; an organic solvent; and an additive; The above additive comprises a compound represented by the following chemical formula 1, The above additive comprises at least one of the compound represented by the above chemical formula 1, ethylene sulfate and 1,3-propane sultone, The compound represented by the above chemical formula 1 is contained in the non-aqueous electrolyte at 0.25 wt% to 1.60 wt%, A non-aqueous electrolyte in which the total content of the compound represented by the above chemical formula 1, ethylene sulfate and 1,3-propane sultone is 0.25 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte: [Chemical Formula 1] In the above chemical formula 1, R1 is -O-NO2, L1 is an alkyleneoxy group having 1 to 5 carbon atoms, M is a metal cation or organic cation, a is the valence of M when M is a metal cation, and 1 when M is an organic cation, a=b.

2. In claim 1, The above M is a metal cation, The above M is a non-aqueous electrolyte selected from the group consisting of Li, K, Ca, Mg and Cs.

3. In claim 1, The above M is an organic cation, The above M is a non-aqueous electrolyte selected from the group consisting of compounds represented by the following chemical formulas M-1 to M-6: [Chemical Formula M-1] In the above chemical formula M-1, X M1 Silver -N(R M15 )- or -S-, and R M11 , R M12 , R M13 , R M14 and R M15 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-2] In the above chemical formula M-2, X M2 Silver -N(R M25 )- or -S-, and R M21 , R M22 , R M23 , R M24 and R M25 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-3] In the above chemical formula M-3, R M31 , R M32 , R M33 , R M34 , R M35 and R M36 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. [Chemical Formula M-4] In the above chemical formula M-4, R M41 , R M42 , R M43 and R M44 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M41 , R M42 , R M43 and R M44 At least two of them are alkyl groups having 1 to 5 carbon atoms, and these can be combined with each other to form an aliphatic hydrocarbon ring. [Chemical Formula M-5] In the above chemical formula M-5, R M51 , R M52 , R M53 and R M54 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoalkyl group having 2 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M51 , R M52 , R M53 and R M54 At least two of these can be combined with each other to form an aliphatic hydrocarbon ring. [Chemical Formula M-6] In the above chemical formula M-6, R M61 , R M62 and R M63 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 12 carbon atoms, an alkynyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a cyanoethyl group having 1 to 12 carbon atoms, an alkoxyalkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and R M61 , R M62 and R M63 At least two of these can be combined with each other to form an aliphatic hydrocarbon ring.

4. In claim 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-A: [Chemical Formula 1-A] In the above chemical formula 1-A, each of M, a, b and R1 is as defined in the above chemical formula 1.

5. In claim 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-A-1: [Chemical Formula 1-A-1] In the above chemical formula 1-A-1, each of M, a, and b is as defined in the above chemical formula 1.

6. In claim 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1-a-1: [Chemical formula 1-a-1] .

7. In claim 1, A non-aqueous electrolyte in which the total content of the compound represented by the above chemical formula 1, ethylene sulfate, and 1,3-propane sultone is 0.75 wt% to 1.60 wt% based on the total weight of the non-aqueous electrolyte.

8. In claim 1, A non-aqueous electrolyte further comprising at least one auxiliary additive selected from the group consisting of a cyclic carbonate compound, a nitrile compound, a benzene compound, a lithium salt compound, an amine compound, and a silane compound.

9. In claim 1, The above organic solvent is a non-aqueous electrolyte containing a carbonate-based organic solvent.

10. In claim 9, The above carbonate-based organic solvent is a non-aqueous electrolyte including a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

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

12. In claim 11, The above negative electrode includes a negative electrode active material, A lithium secondary battery wherein the negative electrode active material comprises at least one selected from a carbon-based active material and a silicon-based active material.

13. In claim 11, The above positive electrode includes a positive electrode active material, A lithium secondary battery wherein the positive electrode active material includes lithium iron phosphate.

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