Nonaqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention provides a nonaqueous electrolyte comprising: a lithium salt; an organic solvent; and a compound represented by Formula 1. [Formula 1] In Formula 1, R1 to R5 are each independently one selected from the group consisting of H, F, a nitrile group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms, and n is an integer from 1 to 5. # imgabs0 #

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of Korean Patent Application Nos. 10 - 2023 - 0126663, filed on September 21, 2023, and 10 - 2024 - 0122725, filed on September 9, 2024, the contents of which are incorporated herein by reference. Technical field

[0003] The present invention relates to a non - aqueous electrolyte and a lithium secondary battery including the non - aqueous electrolyte. Background art

[0004] In recent years, as the application fields of lithium secondary batteries have rapidly expanded from power supply for electronic devices such as electric, electronic, communication, and computer devices to power storage and supply for large - scale devices such as automobiles and power storage devices, the demand for secondary batteries with high capacity, high output, and high stability has been increasing.

[0005] In particular, in lithium secondary batteries for automobiles, high - capacity, high - output, and long - life characteristics have become important. To increase the capacity of secondary batteries, a nickel - rich cathode active material with a high energy density but low stability can be used, or the secondary battery can be driven at a high voltage.

[0006] However, when a secondary battery is driven under the above conditions, due to side reactions caused by the deterioration of the electrolyte during battery charging and discharging, the coating film formed on the surface of the positive electrode / negative electrode or the electrode surface structure may deteriorate, and thus transition metal ions may dissolve out from the positive electrode surface. In this way, if the dissolved transition metal ions are electrodeposited on the negative electrode, the passivation ability of the SEI may be reduced, leading to negative electrode deterioration.

[0007] When the positive electrode potential increases, or when the battery is exposed to high temperatures, the deterioration phenomenon of the secondary battery tends to accelerate.

[0008] In addition, if a lithium - ion battery is used continuously for a long time or placed at a high temperature, gas is generated, resulting in an increase in the battery thickness, which is called the swelling phenomenon. It is known that the amount of gas generated in this case is determined by the state of the SEI.

[0009] Therefore, to solve this problem, attempts are being made to research and develop a method that suppresses the dissolution of metal ions from the positive electrode, forms a stable SEI film on the negative electrode, thereby reducing the swelling phenomenon of the secondary battery and improving the stability at high temperatures. Summary of the invention

[0010] [Technical problem]

[0011] In order to solve the above problems, various studies have been conducted. As a result, the present invention aims to provide an additive for non-aqueous electrolytes that can suppress the deterioration of the positive electrode, reduce side reactions between the positive electrode and the electrolyte, and form a stable SEI film on the negative electrode.

[0012] In addition, the present invention aims to provide a non-aqueous electrolyte having improved high-temperature stability by containing the additive for non-aqueous electrolytes.

[0013] Furthermore, the present invention aims to provide a lithium secondary battery having improved high-temperature cycle characteristics and high-temperature storage characteristics by containing the non-aqueous electrolyte, thereby improving the overall performance.

[0014] [Technical Solution]

[0015] [1] The present invention provides a non-aqueous electrolyte comprising: a lithium salt; an organic solvent; and a compound represented by the following formula 1.

[0016] [Formula 1]

[0017]

[0018] In Formula 1, each of R1 to R5 is independently one selected from the group consisting of H, F, a cyano group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms, and n is an integer from 1 to 5.

[0019] [2] The present invention can provide the non-aqueous electrolyte described in [1], wherein the compound of Formula 1 is represented by the following Formula 1-1.

[0020] [Formula 1-1]

[0021]

[0022] In Formula 1-1, n is an integer from 1 to 5.

[0023] [3] The present invention can provide the non-aqueous electrolyte described in [1], wherein the compound of Formula 1 is a compound selected from the group consisting of the following Formulas 1-2a to 1-2f.

[0024] [Formula 1-2a]

[0025]

[0026] [Formula 1-2b]

[0027]

[0028] [Formula 1-2c]

[0029]

[0030] [Formula 1-2d]

[0031]

[0032] [Formula 1-2e]

[0033]

[0034] [Formula 1-2f]

[0035]

[0036] [4] The present invention can provide the non-aqueous electrolyte according to any one of [1] to [3], wherein, based on 100 parts by weight of the non-aqueous electrolyte, the content of the compound of Formula 1 is 0.01 part by weight to 10 parts by weight.

[0037] [5] The present invention can provide the non-aqueous electrolyte according to any one of [1] to [4], wherein the lithium salt is contained at a concentration of 0.5 M to 2.0 M.

[0038] [6] The present invention can provide the non-aqueous electrolyte according to any one of [1] to [5], wherein the lithium salt is selected from the group consisting of LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2 and one or more thereof.

[0039] [7] The present invention can provide the non-aqueous electrolyte according to any one of [1] to [6], wherein the organic solvent contains at least one organic solvent selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0040] [8] The present invention can provide the non-aqueous electrolyte according to any one of [1] to [7], which further contains one or more compounds selected from the group consisting of cyclic carbonate compounds, halogenated carbonate compounds, sultone compounds, sulfate or ester compounds, phosphate or ester compounds, borate or ester compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds as additives.

[0041] [9]The present invention can provide a lithium secondary battery, comprising: a positive electrode; a negative electrode; and the non-aqueous electrolyte according to any one of [1] to [7].

[0042]

[10] The present invention can provide the lithium secondary battery according to [9], wherein the positive electrode contains a lithium nickel-based oxide represented by Formula 2 below as a positive electrode active material.

[0043] [Formula 2]

[0044] Li x Ni a Co b M 1 c M 2 d O2

[0045] In Formula 2, M 1 is Mn, Al or a combination thereof, M 2 is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, 0.8 ≤ x ≤ 1.2, 0.8 ≤ a < 1, 0 < b < 0.2, 0 < c < 0.2, 0 ≤ d ≤ 0.1.

[0046]

[11] The present invention can provide the lithium secondary battery according to [9] or

[10] , wherein the negative electrode contains SiO x (0 ≤ x < 2) as a negative electrode active material.

[0047] [Advantageous Effects]

[0048] The compound represented by Formula 1 provided as an additive for the non-aqueous electrolyte of the present invention has coumarin as a basic structure. The compound having a coumarin structure has strong reducibility at the negative electrode, causing the ring structure to rapidly undergo a ring-opening reaction in the initial negative electrode film-forming reaction. The resulting polyethylene oxide (PEO)-like polymer film has the characteristic of high elasticity. As a result, even in a lithium secondary battery containing a silicon-based negative electrode active material (which has a large volume change during charge and discharge), the durability of the film is excellent. Therefore, an excellent life characteristic effect can be obtained.

[0049] In addition, the compound of Formula 1 of the present invention can form free radicals to promote the reduction reaction of the organic solvent or other additives contained in the non-aqueous electrolyte, thereby rapidly forming a film with excellent durability.

[0050] Furthermore, the compound of Formula 1 of the present invention can form a film containing inorganic components such as LiF between polymer organic films through BF3 substituted at the 1-position. - Therefore, the film formed by the compound of Formula 1 can be an organic / inorganic composite film and can have excellent durability even when exposed to high temperature or high voltage.

[0051] In addition, the compound of Formula 1 of the present invention exhibits the characteristics of a Lewis acid, where BF3 substituted at the 1-position - can capture anions present in the electrolyte. Thereby, by stabilizing the anions that act as Lewis bases in the electrolyte, the structural transformation of the negative electrode film can be suppressed, and thus the high-temperature storage characteristics of the lithium secondary battery can be improved. In addition, since the reduction product in the electrolyte forms a B-O bond with BF3 substituted at the 1-position of the compound of Formula 1 - the interfacial adhesion force at the negative electrode is enhanced, and thus the strength of the film derived from the compound of Formula 1 is enhanced. As a result, in a lithium secondary battery including a silicon-based negative electrode active material with a large volume change during charge and discharge, the durability of the film is excellent, and thus excellent life characteristics can be achieved.

[0052] Therefore, by suppressing the deterioration of the passivation ability of the SEI at high temperature, the deterioration of the negative electrode can be prevented, and thus the life characteristics of the battery can be improved.

[0053] That is, by using the non-aqueous electrolyte of the present invention containing the compound of Formula 1, a stable electrode-electrolyte interface with low resistance can be formed even at high temperature, and thus the high-temperature cycle characteristics and high-temperature storage characteristics can be improved, thereby realizing a lithium secondary battery with improved overall performance. Detailed Embodiments

[0054] The words or terms used in the description and claims of the present invention should not be construed as having the meanings defined in a common dictionary. Based on the principle that the inventor can appropriately define the meanings of the words or terms to best explain the present invention, the words or terms should be construed as having meanings consistent with the technical concept of the present invention.

[0055] In this specification, the terms "comprising", "including", or "having" are intended to specify the presence of features, numbers, steps, components, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof in advance.

[0056] In addition, in this specification, in the description of "a to b carbon atoms", "a" and "b" each refer to the number of carbon atoms contained in a specific functional group. That is, the functional group may contain "a" to "b" carbon atoms. For example, "an alkylene group having 1 to 5 carbon atoms" refers to an alkylene group having 1 to 5 carbon atoms, namely -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, -CH(CH3)CH2CH2-, etc.

[0057] In addition, in this specification, all of alkyl, alkenyl, and alkynyl can be either substituted or unsubstituted. Unless otherwise defined, the term "substituted" means that at least one hydrogen atom bonded to carbon is replaced by an element other than hydrogen, for example, replaced by a halogen atom such as F and Cl.

[0058] The present invention will be described in more detail below.

[0059] The non-aqueous electrolyte and / or lithium secondary battery of the present invention includes at least one of the configurations disclosed below, and may include any combination between various configurations that are technically feasible among the following configurations.

[0060] Non-aqueous electrolyte

[0061] The non-aqueous electrolyte of the present invention is characterized by containing a compound of the following formula 1 as an additive.

[0062] [Formula 1]

[0063]

[0064] The compound represented by formula 1 has coumarin as a basic structure. The compound having a coumarin structure has strong reducibility at the negative electrode, so that the ring structure rapidly undergoes a ring-opening reaction in the initial negative electrode film-forming reaction. The polyethylene oxide (PEO)-like polymer film formed thereby has the characteristic of high elasticity. As a result, even in a lithium secondary battery containing a silicon-based negative electrode active material (which has a large volume change during charge and discharge), the durability of the film is excellent, and excellent life characteristics are obtained.

[0065] In addition, the compound of formula 1 of the present invention can form free radicals to promote the reduction reaction of the organic solvent or other additives contained in the non-aqueous electrolyte, thereby rapidly forming a film with excellent durability.

[0066] Furthermore, the compound of formula 1 of the present invention can form a film containing inorganic components such as LiF between polymer organic films through BF3 substituted at the 1-position. - Therefore, the film formed by the compound of formula 1 becomes an organic / inorganic composite film, and can have excellent durability even when exposed to high temperature or high voltage.

[0067] In addition, BF3 substituted at the 1-position in the compound of formula 1 of the present invention - exhibits the characteristics of a Lewis acid and can capture anions present in the electrolyte. Thus, by stabilizing the anions as Lewis bases in the electrolyte, the structural deterioration of the negative electrode film can be suppressed, and thereby the high-temperature storage characteristics of the lithium secondary battery can be improved. In addition, due to BF3 substituted at the 1-position of the compound of formula 1 -Form a B-O bond with the reduction product in the electrolyte to enhance the interfacial adhesion at the negative electrode, so the strength of the film derived from the compound of Formula 1 is enhanced. As a result, even in a lithium secondary battery containing a silicon-based negative electrode active material with a large volume change during charge and discharge, the durability of the film is excellent, and thus the life characteristics are excellent.

[0068] Therefore, by suppressing the deterioration of the passivation ability of SEI at high temperatures, the deterioration of the negative electrode can be prevented, and thus the life characteristics of the battery can be improved.

[0069] In Formula 1, R1 to R5 are each independently one selected from H, F, cyano group, alkoxycarbonyl group having 2 to 10 carbon atoms, alkylcarbonyl group having 2 to 10 carbon atoms, alkyl group having 1 to 10 carbon atoms, alkenyl group having 2 to 10 carbon atoms, and alkynyl group having 2 to 10 carbon atoms, and preferably one selected from H, F, cyano group, and alkyl group having 1 to 5 carbon atoms.

[0070] In Formula 1, n is an integer from 1 to 5, and preferably, n can be an integer from 1 to 3.

[0071] Preferably, the compound of Formula 1 can be represented by the following Formula 1-1.

[0072] [Formula 1-1]

[0073]

[0074] In Formula 1-1, n is an integer from 1 to 5, and preferably, n can be an integer from 1 to 3.

[0075] The additive for the non-aqueous electrolyte of the present invention can be one selected from the following Formulas 1-2a to 1-2f.

[0076] [Formula 1-2a]

[0077]

[0078] [Formula 1-2b]

[0079]

[0080] [Formula 1-2c]

[0081]

[0082] [Formula 1-2d]

[0083]

[0084] [Formula 1-2e]

[0085]

[0086] [Formula 1-2f]

[0087]

[0088] Based on 100 parts by weight of the non-aqueous electrolyte, the content of the additive for the non-aqueous electrolyte of the present invention may be 0.01 part by weight to 10 parts by weight, 0.1 part by weight to 5 parts by weight, 0.1 part by weight to 4 parts by weight, 0.3 part by weight to 2 parts by weight, or 0.5 part by weight to 1.0 part by weight. If the content of the compound represented by Formula 1 satisfies the above range, the film-forming effect on the positive electrode is sufficient, so the elution of transition metals from the positive electrode active material is suppressed, and the viscosity of the electrolyte is maintained at an appropriate level, so the rate characteristics or life characteristics during high-temperature storage are excellent.

[0089] The non-aqueous electrolyte of the present invention may further include a lithium salt, an organic solvent, or other electrolyte additives.

[0090] The lithium salt is used as an electrolyte salt in a lithium secondary battery and as a medium for transporting ions. Generally, the lithium salt includes Li + as a cation, and selected from F - , Cl - , Br - , I-, NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P -, C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - as at least one of the anions.

[0091] Specifically, the lithium salt may include a single material selected from LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), lithium bis(perfluoroethylsulfonyl)imide (LiBETI, LiN(SO2CF2CF3)2), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), or a mixture of two or more thereof. In addition, lithium salts commonly used in electrolytes for lithium secondary batteries can be used without limitation.

[0092] The lithium salt can be appropriately changed within a commonly used range. However, in order to obtain the best film-forming effect for the anti-electrode surface corrosion film, it can be included in the electrolyte at a concentration of 0.5 M to 2.0 M, preferably 0.5 M to 1.8 M, and more preferably 0.7 M to 1.6 M. If the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics of the lithium secondary battery during high-temperature storage can be sufficient, and the viscosity of the non-aqueous electrolyte can be appropriate, so the electrolyte impregnation property can be improved.

[0093] The non-aqueous organic solvent may include at least one organic solvent selected from cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0094] Specifically, the organic solvent may include cyclic carbonate organic solvents, linear carbonate organic solvents, or a mixed organic solvent thereof.

[0095] The cyclic carbonate organic solvent is an organic solvent having a high viscosity and a high dielectric constant, which can easily dissociate the lithium salt in the electrolyte. Specific examples thereof include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and ethylene carbonate may be included.

[0096] In addition, linear carbonate organic solvents are organic solvents with low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate. Specifically, it may contain ethyl methyl carbonate (EMC).

[0097] In addition, in order to prepare an electrolyte with high ionic conductivity, in addition to at least one carbonate organic solvent selected from the group consisting of cyclic carbonate organic solvents and linear carbonate organic solvents, the organic solvent may additionally include at least one ester organic solvent selected from the group consisting of linear ester organic solvents and cyclic ester organic solvents.

[0098] The linear ester organic solvents may specifically include, for example, at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0099] In addition, the cyclic ester organic solvents may be at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0100] Meanwhile, if necessary, any organic solvent commonly used in non-aqueous electrolytes may be additionally added to the organic solvent without limitation. For example, it may additionally include at least one organic solvent selected from ether organic solvents, glyme solvents, and nitrile solvents.

[0101] The ether solvents may be any one or a mixture of two or more 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), but the present invention is not limited thereto.

[0102] Glyme solvents are solvents with a high dielectric constant and low surface tension compared to linear carbonate organic solvents and low reactivity with metals, and may include at least one selected from the group consisting of dimethoxyethane (glyme dimethyl ether, DME), diethoxyethane, diglyme dimethyl ether, triglyme dimethyl ether, and tetraethylene glycol dimethyl ether (TEGDME), but are not limited thereto.

[0103] The nitrile solvents may be more than one selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, octanenitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but are not limited thereto.

[0104] In addition, in order to prevent the non-aqueous electrolyte from decomposing in a high-output environment and causing the collapse of the negative electrode, or in order to further improve the low-temperature high-rate discharge characteristics, high-temperature stability, overcharge protection, and high-temperature battery expansion suppression effect, when necessary, the non-aqueous electrolyte of the present invention may additionally contain known non-aqueous electrolyte additives.

[0105] As a representative example, other electrolyte additives may include at least one SEI film-forming additive selected from the group consisting of cyclic carbonate compounds, halogenated carbonate compounds, sultone compounds, sulfate or ester compounds, phosphate or ester compounds, borate or ester compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0106] The cyclic carbonate compounds may include vinylene carbonate (VC) or ethylene vinyl carbonate.

[0107] The halogenated carbonate compounds may include fluoroethylene carbonate (FEC).

[0108] The sultone compounds may include at least one compound selected from 1,3-propane sultone (PS), 1,4-butane sultone, ethylene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone.

[0109] The sulfate or ester compounds may include ethylene sulfite (Esa), trimethylsulfate (TMS), or methyl trimethylsulfate (MTMS).

[0110] The phosphate or ester compounds may include at least one compound selected from the group consisting of lithium difluoro(oxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(2,2,2-trifluoroethyl) phosphite.

[0111] The borate or ester compounds may include tetraphenylborate, lithium oxalyl difluoroborate (LiODFB), and lithium bis(oxalato)borate (LiB(C2O4)2, LiBOB).

[0112] The nitrile compounds may include at least one compound selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, octanenitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0113] The benzene compounds may include fluorobenzene, the amine compounds may include triethanolamine or ethylenediamine, and the silane compounds may include tetraethenylsilane.

[0114] The lithium salt compounds are different from the lithium salts contained in the non-aqueous electrolyte and may include lithium difluorophosphate (LiDFP), LiPO2F2, or LiBF4.

[0115] Among the above other electrolyte additives, if a combination of vinylene carbonate (VC), 1,3-propane sultone (PS), ethylene sulfite (Esa), and lithium difluorophosphate (LiDFP) is additionally included, during the initial activation process of the secondary battery, a stronger SEI film can be formed on the surface of the negative electrode, and the generation of gases that may be produced due to the decomposition of the electrolyte at high temperatures can be inhibited, thereby improving the high-temperature stability of the secondary battery.

[0116] Meanwhile, two or more of the other electrolyte additives can be used in combination, and based on the total weight of the non-aqueous electrolyte, their content can be 0.01 to 30% by weight, specifically 0.1 to 25% by weight, preferably 1 to 20% by weight. If the content of the other electrolyte additives satisfies the above range, the effects of improving ion conductivity and cycling characteristics are more excellent.

[0117] Lithium secondary battery

[0118] The present disclosure also provides a lithium secondary battery including the above non-aqueous electrolyte.

[0119] Specifically, the lithium secondary battery includes: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and the above non-aqueous electrolyte.

[0120] In this case, the lithium secondary battery of the present invention can be manufactured by a common method known in the art. For example, the positive electrode, the negative electrode, and the separator disposed between the positive electrode and the negative electrode are sequentially stacked to form an electrode assembly, and then the electrode assembly is inserted into a battery case and the non-aqueous electrolyte of the present invention is injected to manufacture the battery.

[0121] (1) Positive electrode

[0122] The positive electrode can be manufactured by coating a positive electrode mixture paste including a positive electrode active material, a binder, a conductive material, and a solvent on a positive electrode current collector.

[0123] The positive electrode current collector is not particularly limited as long as it has conductivity and does not cause chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0124] The positive electrode active material is a compound capable of reversibly inserting and extracting lithium. Specifically, it may include lithium metal oxides containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium metal oxides are: lithium manganese-based oxides (e.g., LiMnO2, LiMn2O4), lithium cobalt-based oxides (e.g., LiCoO2), lithium nickel-based oxides (e.g., LiNiO2), lithium nickel manganese-based oxides (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-z Ni z O4 (where 0 < Z < 2)), lithium nickel cobalt-based oxides (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1)), lithium manganese cobalt-based oxides (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2)), lithium nickel manganese cobalt-based oxides (e.g., Li(Ni p Co q Mn r )O2 (where 0 < p < 1, 0 < q < 1, 0 < r < 1 and p + q + r = 1), Li(Ni p1 Co q1 Mn r1 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r1 < 2 and p1 + q1 + r1 = 2)) or lithium nickel cobalt transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O2 (where M is selected from Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are the atomic fractions of the respective elements, where 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1 and p2 + q2 + r3 + s2 = 1)), and may include any one of them or two or more thereof.

[0125] Among them, from the viewpoint of improving the capacity characteristics and stability of the battery, the lithium metal oxide may be LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co0.2 ) O2, Li(Ni 0.7 Mn 0.15 Co 0.15 ) O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 ) O2), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 ) O2), and any one or a mixture of two or more of them can be used.

[0126] Among them, from the viewpoint of maximizing the capacity characteristics of the battery, a positive electrode active material with a nickel content of 80 atm% or more can be used. For example, the lithium transition metal oxide can include one represented by the following formula 2.

[0127] [Formula 2]

[0128] Li x Ni a Co b M 1 c M 2 d O2

[0129] In formula 2, M 1 is at least one selected from Mn and Al, preferably can be Mn, or a combination of Mn and Al.

[0130] M 2 can be one or more selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S.

[0131] x represents the atomic fraction of lithium in the lithium transition metal oxide, and can be 0.90 ≤ x ≤ 1.1, preferably 0.95 ≤ x ≤ 1.08, more preferably 1.0 ≤ x ≤ 1.08.

[0132] a represents the atomic fraction of nickel in the metal elements other than lithium in the lithium transition metal oxide, and can be 0.80 ≤ a < 1.0, preferably 0.80 ≤ a ≤ 0.95, more preferably 0.80 ≤ a ≤ 0.90. If the nickel content satisfies the above range, high capacity characteristics can be achieved.

[0133] b represents the atomic fraction of cobalt in the metal elements other than lithium in the lithium transition metal oxide, and can be 0 < b < 0.2, 0 < b ≤ 0.15, or 0.01 ≤ b ≤ 0.10.

[0134] c represents M in the metal elements other than lithium in the lithium transition metal oxide 1The atomic fraction of c can be 0 < c < 0.2, 0 < c ≤ 0.15, or 0.01 ≤ c ≤ 0.10.

[0135] d represents M among the metal elements other than lithium in the lithium transition metal oxide 2 The atomic fraction of d can be 0 ≤ d ≤ 0.1, or 0 ≤ d ≤ 0.05.

[0136] Relative to the total solid content excluding the solvent in the positive electrode mixture slurry, the content of the positive electrode active material can be 60 to 99% by weight, preferably 70 to 99% by weight, more preferably 80 to 98% by weight.

[0137] The binder is a component that helps bind the active material to the conductive material and to the current collector.

[0138] Examples of the binder include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene - propylene - diene monomer, sulfonated ethylene - propylene - diene monomer, styrene - butadiene rubber, fluororubber, various copolymers thereof, etc.

[0139] Generally, relative to the total weight of the solid content excluding the solvent in the positive electrode mixture slurry, the content of the binder can be 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight.

[0140] The conductive material is a component used to further improve the conductivity of the positive electrode active material, and can be added in an amount of 1 to 20% by weight relative to the total solid content in the positive electrode mixture slurry. There is no particular limitation on the conductive material as long as it has conductivity and does not cause chemical changes in the battery. For example, carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal cracking carbon black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; carbon fluoride powders; conductive powders such as aluminum powder or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives; and so on.

[0141] Generally, relative to the total solid content excluding the solvent in the positive electrode mixture slurry, the content of the conductive material can be 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight.

[0142] The solvent may include an organic solvent such as N-methyl-2-pyrrolidone (NMP), and when including the positive electrode active material and optional binder and conductive material, the amount of the solvent may provide the desired viscosity. For example, the content of the solvent may make the concentration of the solid components including the positive electrode active material and optional binder and conductive material 50 to 95% by weight, preferably 70 to 95% by weight, more preferably 70 to 90% by weight.

[0143] (2) Negative electrode

[0144] The negative electrode can be manufactured, for example, by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, or a graphite electrode made of carbon (C) or the metal itself can be used as the negative electrode.

[0145] For example, if the negative electrode is manufactured by coating a negative electrode mixture slurry on a negative electrode current collector, the negative electrode current collector generally has a thickness of 3 to 500 μm. The negative electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium, and silver, and aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the bonding strength of the negative electrode active material, and the negative electrode current collector can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0146] In addition, the negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly inserting / extracting lithium ions, a metal or an alloy of a metal and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0147] As the carbon material capable of reversibly inserting / extracting lithium ions, any carbon-based negative electrode active material commonly used in lithium ion secondary batteries can be used without particular limitation, and its representative examples include crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite, such as natural graphite or artificial graphite in amorphous, plate-like, flake-like, spherical, or fibrous forms, and examples of amorphous carbon include soft carbon (low-temperature fired carbon) or hard carbon, mesophase pitch carbide, fired coke, etc.

[0148] As the metal or the alloy of a metal and lithium, a metal selected from Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn or an alloy of these metals and lithium can be used.

[0149] As the metal composite oxide, one selected from PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1) and Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8) can be used.

[0150] Materials capable of doping and de-doping lithium include Si, SiO x (0 < x ≤ 2), Si-Y alloy (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, but not Si), Sn, SnO2 and Sn-Y (where Y is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements and combinations thereof, but not Sn), and at least one of them can be used in combination with SiO2. The element Y can be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po and combinations thereof.

[0151] The transition metal oxide can be a lithium-containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, etc.

[0152] Relative to the total weight of the solid components in the negative electrode mixture slurry, the content of the negative electrode active material can be 60 to 99% by weight, preferably 70 to 99% by weight, more preferably 80 to 98% by weight.

[0153] The binder is a component that helps the binding between the conductive material, the active material and the current collector. Examples of the binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber and various copolymers thereof.

[0154] Generally, based on the total weight of the solid components other than the solvent in the negative electrode mixture slurry, the content of the binder can be 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight.

[0155] The conductive material is a component for further improving the conductivity of the negative electrode active material, and can be added in an amount of 1 to 20% by weight based on the total weight of the solid components in the negative electrode mixture slurry. There is no particular limitation on the conductive material as long as it has conductivity and does not cause chemical changes in the battery. For example, the following can be used: carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal cracking carbon black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; carbon fluoride powders; conductive powders such as aluminum powder or nickel powder; conductive whiskers of zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives; and so on.

[0156] Based on the total weight of the solid components excluding the solvent in the negative electrode mixture slurry, the content of the conductive material can be 1 to 20% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight.

[0157] The solvent can include water or an organic solvent such as N-methyl-2-pyrrolidone (NMP), and when the negative electrode active material and optionally the binder and the conductive material are included, the amount of the solvent can provide the required viscosity. For example, the content of the solvent can be such that the concentration of the solid components including the negative electrode active material and optionally the binder and the conductive agent is 50 to 95% by weight, preferably 70 to 90% by weight.

[0158] In the case where the metal itself is used as the negative electrode, the metal thin film itself can be used, or the metal can be physically joined, roll-pressed, or deposited on the negative electrode current collector. The deposition method can use an electroplating method or a chemical vapor deposition method.

[0159] For example, the metal thin film itself or the metal joined / roll-pressed / deposited on the negative electrode current collector can include one metal selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In) or an alloy of two metals.

[0160] (3) Separator

[0161] In addition, as the separator, common porous polymer membranes used as separators in the art can be used alone or in layers, such as porous polymer membranes made of polyolefin polymers (e.g., ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, ethylene / methacrylate copolymers), or conventional porous non-woven fabrics, such as non-woven fabrics made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc., but not limited thereto. In addition, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer material can be used, and it can be used in a single-layer or multi-layer structure optionally.

[0162] The shape of the lithium secondary battery of the present invention is not particularly limited and can be cylindrical, prismatic, bag-shaped, or coin-shaped using a can.

[0163] Hereinafter, the present invention will be described in more detail based on specific embodiments. However, the embodiments are only for helping to understand the present invention and do not limit the scope of the present invention. It will be obvious to those skilled in the art that various modifications and changes can be made within the scope and technical spirit of this specification, and such modifications and changes naturally fall within the scope of the appended claims.

[0164] Examples

[0165] Example 1

[0166] (Preparation of non-aqueous electrolyte)

[0167] Dissolve LiPF6 with a concentration of 1.3 M and vinylene carbonate (VC) with a concentration of 0.5 wt% in an organic solvent (fluoroethylene carbonate (FEC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) = 10:45:45 by volume ratio) to prepare a non-aqueous solvent. Add 0.1 g of the compound of Formula 1-1 to 99.9 g of the non-aqueous solvent to prepare a non-aqueous electrolyte.

[0168] [Formula 1-2a]

[0169]

[0170] (Manufacture of lithium secondary battery)

[0171] The positive electrode active material (LiNi 0.85 Co 0.05 Mn 0.07 Al 0.03O2): The conductive material (carbon nanotubes): binder (polyvinylidene fluoride) was added to N-methyl-2-pyrrolidone (NMP) as a solvent in a weight ratio of 97.74:0.70:1.56 to prepare a positive electrode paste (solid content 75.5 wt%). The positive electrode paste was coated on one side of a positive electrode current collector (Al film) with a thickness of 15 μm, dried and then roll-pressed to form a positive electrode.

[0172] The negative electrode active material (Si): conductive material (carbon black): binder (styrene-butadiene rubber) was added to H2O as a solvent in a weight ratio of 70.0:20.3:9.7 to prepare a negative electrode paste (solid content 26 wt%). The negative electrode paste was coated on one side of a negative electrode current collector (Cu film) with a thickness of 15 μm, dried and then roll-pressed to form a negative electrode.

[0173] In a drying chamber, a polyethylene separator was placed between the above-formed positive and negative electrodes, and the prepared non-aqueous electrolyte was injected to manufacture a secondary battery.

[0174] Example 2

[0175] A secondary battery was manufactured in the same manner as in Example 1, except that 1.0 g of the compound of Formula 1-2b was added to 99.0 g of the non-aqueous solvent prepared in Example 1 to prepare a non-aqueous electrolyte.

[0176] [Formula 1-2b]

[0177]

[0178] Example 3

[0179] A secondary battery was manufactured in the same manner as in Example 1, except that 2.0 g of the compound of Formula 1-2c was added to 98.0 g of the non-aqueous solvent prepared in Example 1 to prepare a non-aqueous electrolyte.

[0180] [Formula 1-2c]

[0181]

[0182] Example 4

[0183] A secondary battery was manufactured in the same manner as in Example 1, except that 1.0 g of the compound of Formula 1-2a was added to 99.0 g of the non-aqueous solvent prepared in Example 1 to prepare a non-aqueous electrolyte.

[0184] Example 5

[0185] A secondary battery was manufactured in the same manner as in Example 1, except that 3.0 g of the compound of Formula 1-2a was added to 97.0 g of the non-aqueous solvent prepared in Example 1 to prepare a non-aqueous electrolyte.

[0186] Example 6

[0187] A secondary battery was manufactured in the same manner as in Example 1, except that 5.0 g of the compound of Formula 1-2a was added to 95.0 g of the non-aqueous solvent prepared in Example 1 to prepare a non-aqueous electrolyte.

[0188] Comparative Example 1

[0189] A secondary battery was manufactured in the same manner as in Example 1, except that 100 g of the non-aqueous solvent prepared in Example 1 was used to prepare a non-aqueous electrolyte.

[0190] Comparative Example 2

[0191] A secondary battery was manufactured in the same manner as in Example 1, except that 0.5 g of the compound of Formula A was added to 99.5 g of the non-aqueous solvent prepared in Example 1 instead of the compound of Formula 1-2a to prepare a non-aqueous electrolyte.

[0192] [Formula A]

[0193]

[0194] Experimental Example 1 - Evaluation of High-Temperature Cycling Characteristics

[0195] The cycling characteristics of each of the secondary batteries manufactured in Examples 1 to 6 and Comparative Examples 1 and 2 were evaluated.

[0196] Specifically, each of the batteries manufactured in Examples 1 to 6, Comparative Examples 1 and 2 was charged at a constant current of 0.33C to 4.2V at 45 °C, then charged at a constant voltage to 1 / 40C, and then discharged at a constant current of 0.33C to 2.5V. This constitutes one cycle, and then 100 charge-discharge cycles were performed, and the resistance increase rate compared with the initial resistance after 100 cycles was measured. The results are shown in Table 1 below.

[0197] [Table 1]

[0198] Resistance increase rate (%) Example 1 50.4 Example 2 36.8 Example 3 54.9 Example 4 47.6 Example 5 48.5 Example 6 66.2 Comparative Example 1 94.6 Comparative Example 2 67.3

[0199] As shown in Table 1, Examples 1 to 6 using the additive for non-aqueous electrolyte of the present invention had a lower resistance increase rate than Comparative Example 1 without using the additive, and thus had excellent life characteristics. In addition, it was also confirmed that Examples 1 to 6 using the additive for non-aqueous electrolyte of the present invention and the additive of Formula A (which does not have BF3-containing at the 1-position of coumarin) -Compared with Comparative Example 2 (substituent), the resistance increase rate is low, so the life characteristics are excellent.

[0200] Experimental Example 2 - Evaluation of High Temperature Storage Characteristics

[0201] The high temperature storage characteristics of each secondary battery manufactured in Examples 1 to 6 and Comparative Examples 1 and 2 were evaluated.

[0202] Specifically, the secondary batteries of Examples 1 to 6 and Comparative Examples 1 and 2 were each charged to 4.2 V, and then stored at 60 °C for 4 weeks.

[0203] Before storage, the volume of the fully charged secondary battery was measured and set as the initial secondary battery volume.

[0204] After 4 weeks, the volume of the stored secondary battery was measured again, and the increased volume during the 4-week storage was calculated. The percentage of the increased volume relative to the initial secondary battery volume was calculated to obtain the volume increase rate after 4 weeks. The results are shown in Table 2 below.

[0205] [Table 2]

[0206] Volume increase rate (%) Example 1 12.2 Example 2 9.6 Example 3 6.8 Example 4 10.4 Example 5 4.3 Example 6 3.1 Comparative Example 1 16.0 Comparative Example 2 24.8

[0207] As shown in Table 2 above, compared with the secondary battery of Comparative Example 1 that does not use the additive for non-aqueous electrolyte of the present invention, the secondary batteries of Examples 1 to 6 showed a smaller volume increase rate after 4 weeks, so less gas was generated at high temperature. In addition, it was also confirmed that Examples 1 to 6 using the additive for non-aqueous electrolyte of the present invention and Comparative Example 2 using the additive of formula A (which does not have a substituent containing BF3 at the 1-position of coumarin) - showed a smaller volume increase rate after 4 weeks, so less gas was generated at high temperature.

Claims

1. A non-aqueous electrolyte, comprising: a lithium salt; an organic solvent; and a compound represented by Formula 1 below: [Formula 1] In Formula 1, R1 to R5 are each independently one selected from the group consisting of H, F, a nitrile group, an alkoxycarbonyl group having 2 to 10 carbon atoms, an alkylcarbonyl group having 2 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, and an alkynyl group having 2 to 10 carbon atoms, and n is an integer from 1 to 5.

2. The non-aqueous electrolyte according to claim 1, wherein The compound of Formula 1 is represented by Formula 1-1 below: [Formula 1-1] In Formula 1-1, n is an integer from 1 to 5.

3. The non-aqueous electrolyte according to claim 1, wherein, The compound of Formula 1 is one selected from the group consisting of Formula 1-2a to Formula 1-2f below: [Formula 1-2a] [Formula 1-2b] [Formula 1-2c] [Formula 1-2d] [Formula 1-2e] [Formula 1-2f] 4. The non-aqueous electrolyte according to claim 1, wherein, Based on 100 parts by weight of the non-aqueous electrolyte, the content of the compound of Formula 1 is 0.01 part by weight to 10 parts by weight.

5. The non-aqueous electrolyte according to claim 1, wherein The lithium salt is contained at a concentration of 0.5 M to 2.0 M.

6. The non-aqueous electrolyte according to claim 1, wherein, The lithium salt is selected from one or more of the group consisting of LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2.

7. The non-aqueous electrolyte according to claim 1, wherein The organic solvent contains one or more organic solvents selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

8. The non-aqueous electrolyte according to claim 1, further comprising one or more compounds selected from the group consisting of cyclic carbonate compounds, halogenated carbonate compounds, sultone compounds, sulfate or ester compounds, phosphate or ester compounds, borate or ester compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds as additives.

9. A lithium secondary battery, comprising: a positive electrode; a negative electrode; and the non-aqueous electrolyte according to any one of claims 1 to 8.

10. The lithium secondary battery according to claim 9, wherein, The positive electrode contains a lithium nickel-based oxide represented by Formula 2 below as a positive electrode active material, [Formula 2] Li x Ni a Co b M 1 c M 2 d O2 In Formula 2, M 1 is Mn, Al, or a combination thereof, and M 2 is one or more selected from the group consisting of Zr, W, Y, Ba, Ca, Ti, Mg, Ta, and Nb, 0.8 ≤ x ≤ 1.2, 0.8 ≤ a < 1, 0 < b < 0.2, 0 < c < 0.2, 0 ≤ d ≤ 0.

1.

11. The lithium secondary battery according to claim 9, wherein, The negative electrode contains SiO x as the negative electrode active material, where 0 ≤ x < 2.

Images