Non-aqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention relates to a non-aqueous electrolyte and a lithium secondary battery comprising same. The non-aqueous electrolyte comprises a lithium salt, an organic solvent, and an additive, the additive comprising a first additive and a second additive, wherein the first additive comprises a compound in which two cyclic sulfur oxide groups are bonded directly or via a linker, and the second additive comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a propargyl group.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same

[0001] The present invention relates to a non-aqueous electrolyte and a lithium secondary battery containing the same.

[0002] Recently, as the application areas of lithium-ion batteries have rapidly expanded to include not only power supply for electronic devices such as electrical, electronic, telecommunications, and computers, but also power storage for large-area devices such as automobiles and power storage systems, there is a growing demand for high-capacity, high-output, and high-stability secondary batteries.

[0003] In particular, with the growing interest in solving environmental problems and realizing a sustainable circular society, research on energy storage devices such as lithium-ion batteries and electric double-layer capacitors is being conducted extensively. Among these, lithium-ion batteries are receiving attention as battery systems that theoretically have the highest energy density within battery technology.

[0004] The aforementioned lithium secondary battery is largely composed of a positive electrode made of a transition metal oxide containing lithium, a negative electrode capable of storing lithium, an electrolyte that acts as a medium for transporting lithium ions, and a separator. Among these components, the electrolyte is known to have a significant impact on the battery's stability and safety, and as such, extensive research is being conducted on it.

[0005] Meanwhile, high operating voltages are required to achieve high energy density in lithium secondary batteries. However, when operating at such high voltages, problems such as electrolyte depletion due to oxidative decomposition reactions of the electrolyte, gas generation, and the leaching of transition metals from the cathode active material lead to issues such as reduced battery lifespan, storage performance, and durability.

[0006] One objective of the present invention is to solve the above-mentioned problems by providing a non-aqueous electrolyte that effectively protects the negative electrode by minimizing gas generation that may occur during the operation of a secondary battery, and enables improved lifespan, reduced resistance, and enhanced durability of the secondary battery.

[0007] In addition, another objective of the present invention is to provide a lithium secondary battery comprising the aforementioned non-aqueous electrolyte.

[0008] [1] The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a first additive and a second additive, wherein the first additive comprises a compound in which two cyclic sulfates are directly bonded or bonded through a linker, and the second additive comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group.

[0009] [2] The present invention provides a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1, wherein the first additive in [1] is a compound represented by the following chemical formula 1.

[0010] [Chemical Formula 1]

[0011] R a -L a -R L -L b -R b

[0012] In the above chemical formula 1, R a and R b is independently selected from the following formulas R-1 to R-3, and L a and L b are independently directly bonded or are alkylene groups having 1 to 5 carbon atoms, and R L It is selected from direct bonds, alkylene groups having 1 to 5 carbon atoms, and substituents represented by the following formulas L-1 to L-7.

[0013] [Chemical Formula R-1]

[0014]

[0015] [Chemical Formula R-2]

[0016]

[0017] [Chemical Formula R-3]

[0018]

[0019] [Chemical Formula L-1]

[0020]

[0021] [Chemical Formula L-2]

[0022]

[0023] [Chemical Formula L-3]

[0024]

[0025] [Chemical Formula L-4]

[0026]

[0027] [Chemical Formula L-5]

[0028]

[0029] [Chemical Formula L-6]

[0030]

[0031] [Chemical Formula L-7]

[0032]

[0033] In the above chemical formulas R-1 to R-3 and L-1 to L-7, * is a binding site, and R L1 and R L2 The groups are independently selected from hydrogen, fluorine (F), and alkyl groups having 1 to 3 carbon atoms.

[0034] [3] The present invention provides a non-aqueous electrolyte comprising at least one compound selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-4, wherein the compound represented by chemical formula 1 is the compound represented by chemical formula 1-1.

[0035] [Chemical Formula 1-1]

[0036]

[0037] [Chemical Formula 1-2]

[0038]

[0039] [Chemical Formula 1-3]

[0040]

[0041] [Chemical Formula 1-4]

[0042]

[0043] [4] The present invention provides a non-aqueous electrolyte comprising at least one of [1] to [3], wherein the second additive comprises at least one selected from the group consisting of compounds represented by the following formulas 2-1 and 2-2.

[0044] [Chemical Formula 2-1]

[0045]

[0046] In the above chemical formula 2-1, Y 11 is nitrogen (N) or R Y11 is the substituted carbon (C), and Y 12 is oxygen (O), sulfur (S), R Y121 nitrogen (N) or R substituted Y122 and R Y123 is the substituted carbon (C), and Y 13 is nitrogen (N) or R Y13 is the substituted carbon (C), and Y 14 is nitrogen (N) or R Y14 is the substituted carbon (C), and Y 15 is nitrogen (N) or R Y15 is the substituted carbon (C), and here, Y 11 and Y 15 At least one of them is nitrogen (N), and Y 11 , Y 12 , Y 13 , Y 14 , and Y 15At least one of them is carbon (C), and R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 At least one of them is a substituent represented by the above chemical formula 2-a, and

[0047] [Chemical Formula 2-2]

[0048]

[0049] In the above chemical formula 2-2, Y 21 is nitrogen (N) or R Y21 is the substituted carbon (C), and Y 22 is nitrogen (N) or R Y22 is the substituted carbon (C), and Y 23 is nitrogen (N) or R Y23 is the substituted carbon (C), and Y 24 is nitrogen (N) or R Y24 is the substituted carbon (C), and Y 25 is nitrogen (N) or R Y25 is the substituted carbon (C), and in this case, Y 21 , Y 22 , Y 23 , Y 24 and Y 25 At least one of them is carbon (C), and R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y21 , R Y22, R Y23 , R Y24 and R Y25 At least one of them is a substituent represented by the above chemical formula 2-a, and

[0050] [Chemical Formula 2-a]

[0051]

[0052] In the above chemical formula 2-a, L Y1 is selected from direct bonds, esters, ethers, and alkylene groups having 1 to 5 carbon atoms, and R Y1 is a directly bonded or C1 to C5 alkylene group, and R Y2 It is *-CH=CH2 or *-C≡CH, where * is the bonding site.

[0053] [5] The present invention provides a non-aqueous electrolyte comprising at least one compound selected from the group consisting of the compounds represented by the following formulas 2-1-A, 2-1-B, 2-1-C, 2-1-D, 2-1-E and 2-1-F, wherein the compound represented by formula 2-1 is represented by formula 2-1.

[0054] [Chemical Formula 2-1-A]

[0055]

[0056] [Chemical Formula 2-1-B]

[0057]

[0058] [Chemical Formula 2-1-C]

[0059]

[0060] [Chemical Formula 2-1-D]

[0061]

[0062] [Chemical Formula 2-1-E]

[0063]

[0064] [Chemical Formula 2-1-F]

[0065]

[0066] In the above chemical formulas 2-1-A, 2-1-B, 2-1-C, 2-1-D, 2-1-E, and 2-1-F, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is as defined in Chemical Formula 2-1.

[0067] [6] The present invention provides a non-aqueous electrolyte comprising at least one compound selected from the group consisting of the compounds represented by the following formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D and 2-2-E, wherein the compound represented by formula 2-2 is the compound represented by formula 2-2.

[0068] [Chemical Formula 2-2-A]

[0069]

[0070] [Chemical Formula 2-2-B]

[0071]

[0072] [Chemical Formula 2-2-C]

[0073]

[0074] [Chemical Formula 2-2-D]

[0075]

[0076] [Chemical Formula 2-2-E]

[0077]

[0078] In the above chemical formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D, and 2-2-E, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is as defined in Chemical Formula 2-2.

[0079] [7] The present invention provides a non-aqueous electrolyte comprising at least one compound selected from the group consisting of compounds represented by the following formulas 2-1-A1 to 2-1-A4, wherein the second additive comprises at least one compound selected from the group consisting of at least one compound represented by the following formulas 2-1-A1 to 2-1-A4.

[0080] [Chemical Formula 2-1-A1]

[0081]

[0082] [Chemical Formula 2-1-A2]

[0083]

[0084] [Chemical Formula 2-1-A3]

[0085]

[0086] [Chemical Formula 2-1-A4]

[0087]

[0088] [8] The present invention provides a non-aqueous electrolyte in which, in at least one of [1] to [7], the first additive is included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight.

[0089] [9] The present invention provides a non-aqueous electrolyte in which, in at least one of [1] to [8], the second additive is included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight.

[0090]

[0010] The present invention provides a non-aqueous electrolyte in which the weight ratio of the first additive and the second additive is 1:1 to 40:1 in at least one of [1] to [9].

[0091]

[0011] The present invention provides a lithium secondary battery comprising: a cathode; an anode facing the cathode; a separator interposed between the cathode and the anode; and a non-aqueous electrolyte according to at least one of [1] to [9].

[0092] The non-aqueous electrolyte of the present invention is characterized by comprising a combination of a first additive and a second additive as additives. The first additive comprises a compound in which two cyclic sulfur oxides are directly bonded or bonded through a linker, and the second additive comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group. According to the present invention, the first additive and the second additive react with each other to form a reaction product, and since this reaction product can continuously participate in the formation of an electrode film during the charging and discharging of a lithium secondary battery, it is possible to realize a battery with enhanced high-temperature durability and lifespan performance, while simultaneously controlling heat generation characteristics and hot box safety.

[0093] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0094] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0095] Meanwhile, prior to describing the present invention, unless otherwise specifically stated in the present invention, "*" refers to a connected portion (bonding site) between identical or different atoms or terminal portions of a chemical formula.

[0096] In addition, in the description of "a to b carbon atoms" within this 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, "alkyl group having 1 to 5 carbon atoms" refers to an alkyl group containing 1 to 5 carbon atoms, namely CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2CH2-, etc.

[0097] In addition, in this specification, alkyl groups or aryl groups may all be substituted or unsubstituted. Unless otherwise defined, the term "substitution" above means that at least one hydrogen bonded to a carbon is substituted with an element other than hydrogen, for example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, a cycloalkenyl group having 3 to 12 carbon atoms, a cycloalkynyl group having 3 to 12 carbon atoms, a heterocycloalkyl group having 3 to 12 carbon atoms, a heterocycloalkynyl group having 2 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group, an aryl group having 6 to 20 carbon atoms, and a group having 2 to It means that it is substituted with a heteroaryl group of 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, etc.

[0098]

[0099] The present invention will be described in more detail below.

[0100]

[0101] Non-aqueous electrolytes

[0102] The present invention relates to a non-aqueous electrolyte.

[0103] Specifically, the non-aqueous electrolyte according to the present invention comprises a lithium salt, an organic solvent, and an additive, wherein the additive comprises a first additive and a second additive, wherein the first additive comprises a compound in which two cyclic sulfates are directly bonded or bonded through a linker, and the second additive comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group.

[0104] The non-aqueous electrolyte of the present invention is characterized by comprising a combination of a first additive and a second additive as additives. The first additive comprises a compound in which two cyclic sulfur oxides are directly bonded or bonded through a linker, and the second additive comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group. According to the present invention, the first additive and the second additive react with each other to form a reaction product, and since this reaction product can continuously participate in the formation of an electrode film during the charging and discharging of a lithium secondary battery, it is possible to realize a battery with enhanced high-temperature durability and lifespan performance, while simultaneously controlling heat generation characteristics and hot box safety.

[0105]

[0106] (1) Lithium salt

[0107] As the lithium salt used in the present invention, various lithium salts commonly used in non-aqueous electrolytes for lithium secondary batteries may be used without limitation. For example, the lithium salt is Li as a cation. + It includes, and as anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , 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 a group consisting of

[0108] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10It may include at least one selected from the group consisting of 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).

[0109] The above lithium salt may be included in the above-mentioned non-aqueous electrolyte at a concentration of 0.5M to 5M, specifically 0.8M to 4M, and more specifically 0.8M to 2.0M. When the concentration of the above-mentioned lithium salt satisfies the above range, the lithium ion yield (Li + The transference number and the degree of dissociation of lithium ions are improved, which can enhance the output characteristics of the battery.

[0110]

[0111] (2) Organic solvent

[0112] The above organic solvent is a non-aqueous solvent commonly used in lithium secondary batteries, and is not particularly limited as long as it minimizes decomposition due to oxidation reactions, etc., during the charging and discharging process of the secondary battery.

[0113] Specifically, the organic solvent may include at least one selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, linear ester-based organic solvents, and cyclic ester-based organic solvents.

[0114] Specifically, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixture thereof.

[0115] The above-mentioned cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and can effectively dissociate lithium salts in the electrolyte. Specifically, it 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. More specifically, it may include at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC), and even more specifically, it may include ethylene carbonate (EC).

[0116] In addition, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and specifically may include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate; more specifically, may include at least one selected from the group consisting of ethylmethyl carbonate (EMC) and diethyl carbonate (DEC); and even more specifically, may include ethylmethyl carbonate (EMC).

[0117] The above organic solvent may be a mixture of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent. In this case, the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed in a volume ratio of 5:95 to 40:60, specifically in a volume ratio of 10:90 to 30:70. When the mixing ratio of the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent satisfies the above range, high dielectric constant and low viscosity characteristics are simultaneously satisfied, and excellent ionic conductivity characteristics can be achieved.

[0118] In addition, to produce an electrolyte having high ionic conductivity, the organic solvent may further include at least one ester-based organic solvent selected from the group consisting of a linear ester-based organic solvent and a cyclic ester-based organic solvent in addition to at least one carbonate-based organic solvent selected from the group consisting of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[0119] The above linear ester-based organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0120] In addition, the above-mentioned cyclic ester-based 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.

[0121]

[0122] Meanwhile, the above organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes as needed. For example, it may additionally include at least one organic solvent among ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents.

[0123] As the above ether-based solvent, any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methylpropyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more of these may be used, but is not limited thereto.

[0124] The above-mentioned glyme-based solvent has a high dielectric constant and low surface tension compared to linear carbonate-based organic solvents and is a solvent with low reactivity with metals. It may include at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME), but is not limited thereto.

[0125] The above nitrile-based solvent may be one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0126]

[0127] (3) Additives

[0128] The above-mentioned non-aqueous electrolyte contains additives.

[0129] The above additive may include a first additive and a second additive.

[0130] The first additive may include a compound in which two cyclic sulfates are directly bonded or bonded through a linker. The second additive may include a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group.

[0131] The first additive comprises a compound in which two cyclic sulfates are directly bonded or bonded through a linker (a substituent having two bonding sites that bond the cyclic sulfates). The first additive undergoes a ring-opening reaction during activation or battery charging and discharging, thereby enabling the formation of a flexible, highly covering, and highly durable polymer-type electrode film.

[0132] Meanwhile, during the charging, discharging, and storage of lithium secondary batteries, issues such as the desorption of reactive oxygen from the cathode active material, structural collapse of the cathode active material due to the desorption of reactive oxygen, and the leaching of transition metals may arise. The reactive oxygen reacts with the organic solvent of the electrolyte to generate byproducts such as CO, CO2, and H2O. Among these, H2O decomposes the lithium salt to produce HF, and this HF promotes the leaching of transition metals and desorbs oxygen again, which can accelerate the degradation of lifespan and storage performance. In particular, this problem is exacerbated during high-voltage operation. At this time, the second additive acts as a Lewis base capable of capturing HF, which is a Lewis acid, thereby blocking the generation of reactive oxygen caused by HF.

[0133] Meanwhile, the first additive and the second additive can react with each other to form an adduct. Specifically, the adduct is formed through a reaction in which one or two cyclic sulfur oxides present in the first additive are ring-opened by lone pairs of electrons present on the nitrogen of a nitrogen-containing heteroaromatic compound. This adduct remains continuously present during the charging and discharging of the lithium secondary battery and contributes to the formation of the electrode film. Therefore, it is possible to continuously provide an SEI film to counteract the leaching of the anode transition metal during high-voltage and high-temperature operation and the destruction of the anode SEI film by the leached transition metal. Furthermore, the vinyl or proparzyl groups present in the second additive can further improve accessibility to the anode, thereby facilitating the formation of a sulfur-containing SEI film. Accordingly, in the case of a non-aqueous electrolyte in which the first and second additives are used in combination, it is possible to realize a battery with enhanced high-temperature durability and lifespan performance, while simultaneously controlling heat generation characteristics and improving hot box safety.

[0134]

[0135] The first additive may include a compound in which two cyclic sulfates are directly bonded or bonded through a linker. The linker may be, for example, an alkylene group having 1 to 5 carbon atoms.

[0136] Specifically, the first additive may include a compound represented by the following chemical formula 1.

[0137] [Chemical Formula 1]

[0138] R a -L a -R L -L b -R b

[0139] In the above chemical formula 1, R a and R b is independently selected from the following formulas R-1 to R-3, and L a and L b are independently directly bonded or are alkylene groups having 1 to 5 carbon atoms, and R L It is selected from direct bonds, alkylene groups having 1 to 5 carbon atoms, and substituents represented by the following formulas L-1 to L-7.

[0140] [Chemical Formula R-1]

[0141]

[0142] [Chemical Formula R-2]

[0143]

[0144] [Chemical Formula R-3]

[0145]

[0146] [Chemical Formula L-1]

[0147]

[0148] [Chemical Formula L-2]

[0149]

[0150] [Chemical Formula L-3]

[0151]

[0152] [Chemical Formula L-4]

[0153]

[0154] [Chemical Formula L-5]

[0155]

[0156] [Chemical Formula L-6]

[0157]

[0158] [Chemical Formula L-7]

[0159]

[0160] In the above chemical formulas R-1 to R-3 and L-1 to L-7, * is a binding site, and R L1 and R L2 The groups are independently selected from hydrogen, fluorine (F), and alkyl groups having 1 to 3 carbon atoms.

[0161] The compound represented by Chemical Formula 1 above has a structure in which two cyclic sulfates are bonded together, and these cyclic sulfates are each ring-opened, enabling the formation of an electrode film with wide coverage. In this case, the compound represented by Chemical Formula 1 is not formed by the bonding of two cyclic sulfates in, for example, a spiro structure, but rather by direct bonding or through a linker. In the case of cyclic sulfates with a spiro structure, charge density is concentrated at specific points due to the nature of the electron-withdrawing group of the sulfates and their polar structure; this can lead to problems such as reduced solubility in non-aqueous electrolytes, increased viscosity of non-aqueous electrolytes, and interference with the insertion / extraction of lithium ions. In this regard, the structure in which the two cyclic sulfates included in the compound represented by Chemical Formula 1 are each bonded via a single carbon atom. Furthermore, in the compound represented by Chemical Formula 1, the bonding of the two cyclic sulfates does not involve a spiro bond.

[0162] In the above chemical formula 1, R a and R b can be independently selected from the above formulas R-1 to R-3. L a and L b The groups may be independently directly bonded or have 1 to 5 carbon atoms, and specifically, may be independently directly bonded or be methylene groups.

[0163] R L The group may be selected from a direct bond, an alkylene group having 1 to 5 carbon atoms, and a substituent represented by the formulas L-1 to L-7, and specifically, it may be a direct bond, a substituent represented by the formula L-4, or a substituent represented by the formula L-7.

[0164] In the above chemical formula L-7, R L1 and R L2The groups can be independently selected from hydrogen, fluorine (F), and alkyl groups having 1 to 3 carbon atoms, specifically, they can be independently hydrogen or fluorine, and more specifically, they can be independently hydrogen.

[0165] Specifically, the compound represented by Chemical Formula 1 may include at least one selected from the group consisting of compounds represented by Chemical Formulas 1-1 to 1-4 below. More specifically, the compound represented by Chemical Formula 1 may include a compound represented by Chemical Formula 1-2 below.

[0166] [Chemical Formula 1-1]

[0167]

[0168] [Chemical Formula 1-2]

[0169]

[0170] [Chemical Formula 1-3]

[0171]

[0172] [Chemical Formula 1-4]

[0173]

[0174] The first additive may be included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight. Specifically, the first additive may be included in the non-aqueous electrolyte in an amount of 0.001% or more, 0.01% or more, 0.05% or more, 0.1% or more, 0.3% or more, 0.5% or more, 0.7% or more, or 1% or more by weight. Additionally, the first additive may be included in the non-aqueous electrolyte in an amount of 10% or less by weight, 9% or less by weight, 8% or less by weight, 7% or less by weight, 6% or less by weight, 5% or less by weight, 4% or less by weight, 3% or less by weight, 2.5% or less by weight, 2% or less by weight, 1.5% or less by weight, or 1% or less by weight. When the first additive is included within the above content range, it is desirable in terms of forming a cyclic sulfur oxide-derived electrode film to a uniform and thin level.

[0175]

[0176] The second additive above comprises a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group.

[0177] Specifically, it may include at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1 and 2-2.

[0178] [Chemical Formula 2-1]

[0179]

[0180] In the above chemical formula 2-1, Y 11 is nitrogen (N) or R Y11 is the substituted carbon (C), and Y 12 is oxygen (O), sulfur (S), R Y121 nitrogen (N) or R substituted Y122 and R Y123 is the substituted carbon (C), and Y 13 is nitrogen (N) or R Y13 is the substituted carbon (C), and Y 14 is nitrogen (N) or R Y14 is the substituted carbon (C), and Y15 is nitrogen (N) or R Y15 is the substituted carbon (C), and here, Y 11 and Y 15 At least one of them is nitrogen (N), and Y 11 , Y 12 , Y 13 , Y 14 , and Y 15 At least one of them is carbon (C), and R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 At least one of them is a substituent represented by the above chemical formula 2-a.

[0181] [Chemical Formula 2-2]

[0182]

[0183] In the above chemical formula 2-2, Y 21 is nitrogen (N) or R Y21 is the substituted carbon (C), and Y 22 is nitrogen (N) or R Y22 is the substituted carbon (C), and Y 23 is nitrogen (N) or R Y23 is the substituted carbon (C), and Y 24 is nitrogen (N) or R Y24 is the substituted carbon (C), and Y 25 is nitrogen (N) or R Y25 is the substituted carbon (C), and in this case, Y 21 , Y 22 , Y 23 , Y 24 and Y 25At least one of them is carbon (C), and R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y21 , R Y22 , R Y23 , R Y24 and R Y25 At least one of them is a substituent represented by the above chemical formula 2-a.

[0184] [Chemical Formula 2-a]

[0185]

[0186] In the above chemical formula 2-a, L Y1 is selected from direct bonds, esters, ethers, and alkylene groups having 1 to 5 carbon atoms, and R Y1 is a directly bonded or C1 to C5 alkylene group, and R Y2 It is *-CH=CH2 or *-C≡CH, where * is the bonding site.

[0187] In the above chemical formula 2-1, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 ☐ can be independently selected from hydrogen, alkyl groups having 1 to 3 carbon atoms, and substituents represented by the following chemical formula 2-a. Specifically, in the above chemical formula 2-1, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 can be independently selected from hydrogen, a methyl group, and a substituent represented by the following chemical formula 2-a. In this case, R Y11 , R Y121 , R Y122, R Y123 , R Y13 , R Y14 and R Y15 At least one of them may be a substituent represented by the above chemical formula 2-a. Specifically, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 One of them may be a substituent represented by the above chemical formula 2-a, and the remainder that is not a substituent represented by the above chemical formula 2-a may independently be hydrogen or an alkyl group having 1 to 3 carbon atoms, specifically hydrogen or a methyl group, more specifically hydrogen.

[0188] In the above chemical formula 2-2, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 can be independently selected from hydrogen, alkyl groups having 1 to 3 carbon atoms, and substituents represented by the following chemical formula 2-a. Specifically, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 can be independently selected from hydrogen, a methyl group, and a substituent represented by the following chemical formula 2-a. In this case, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 At least one of them may be a substituent represented by the above chemical formula 2-a. Specifically, R Y21 , R Y22 , R Y23 , R Y24 and R Y25Any one of them may not be a substituent represented by the above formula 2-a, and the others may independently be hydrogen or an alkyl group having 1 to 3 carbon atoms, specifically hydrogen or a methyl group, more specifically hydrogen. In this case, hydrogen or an alkyl group having 1 to 3 carbon atoms does not cause steric hindrance and thus does not impede the anodic film-forming effect of the substituent represented by the above formula 2-a or the HF scavenging effect of the nitrogen-containing heteroaromatic compound of formula 2-1 and / or formula 2-2.

[0189] In the above chemical formula 2-a, L Y1 ... can be selected from direct bonds, esters (*-C(=O)O-*), ethers (*-O-*), and alkylene groups having 1 to 5 carbon atoms. Specifically, L Y1 It can be a direct bond or an ester. More specifically, L Y1 It may be an ester. The above L Y1 In the case of this ester (*-C(=O)O-*), the bonding positions of the two bonding sites (*) are not particularly restricted, but the bonding site adjacent to oxygen is R Y1 It is bonded to, and the bonding site adjacent to the carbonyl carbon is R Y1 A bonding site that is not bonded to, specifically Y 11 , Y 12 , Y 13 , Y 14 , or Y 15 ; Y 21 , Y 22 , Y 23 , Y 24 or Y 25 It can be combined with ;.

[0190] R Y1 may be a direct bond or an alkylene group having 1 to 5 carbon atoms. Specifically, R Y1 It may be a direct bond or an alkylene group having 1 to 3 carbon atoms.

[0191] R Y2It can be *-CH=CH2 or *-C≡CH, and specifically *-C≡CH.

[0192]

[0193] The compound represented by the above chemical formula 2-1 may include at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1-A, 2-1-B, 2-1-C, 2-1-D, 2-1-E, and 2-1-F, and specifically may include the compound represented by the following chemical formula 2-1-A.

[0194] [Chemical Formula 2-1-A]

[0195]

[0196] [Chemical Formula 2-1-B]

[0197]

[0198] [Chemical Formula 2-1-C]

[0199]

[0200] [Chemical Formula 2-1-D]

[0201]

[0202] [Chemical Formula 2-1-E]

[0203]

[0204] [Chemical Formula 2-1-F]

[0205]

[0206] In the above chemical formulas 2-1-A, 2-1-B, 2-1-C, 2-1-D, 2-1-E, and 2-1-F, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is as defined in Chemical Formula 2-1.

[0207] The compound represented by the above chemical formula 2-2 may include at least one selected from the group consisting of compounds represented by the following chemical formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D, and 2-2-E.

[0208] [Chemical Formula 2-2-A]

[0209]

[0210] [Chemical Formula 2-2-B]

[0211]

[0212] [Chemical Formula 2-2-C]

[0213]

[0214] [Chemical Formula 2-2-D]

[0215]

[0216] [Chemical Formula 2-2-E]

[0217]

[0218] In the above chemical formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D, and 2-2-E, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is as defined in Chemical Formula 2-2.

[0219]

[0220] Specifically, the second additive may include at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1-A1 to 2-1-A4, and more specifically, may include a compound represented by the chemical formula 2-1-A1.

[0221] [Chemical Formula 2-1-A1]

[0222]

[0223] [Chemical Formula 2-1-A2]

[0224]

[0225] [Chemical Formula 2-1-A3]

[0226]

[0227] [Chemical Formula 2-1-A4]

[0228]

[0229]

[0230] The second additive may be included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight. Specifically, the second additive may be included in the non-aqueous electrolyte in an amount of 0.001% or more by weight, 0.01% or more by weight, 0.02% or more by weight, 0.05% or more by weight, 0.07% or more by weight, or 0.1% or more by weight. Additionally, the second additive may be included in the non-aqueous electrolyte in an amount of 10% or less by weight, 9% or less by weight, 8% or less by weight, 7% or less by weight, 6% or less by weight, 5% or less by weight, 4% or less by weight, 3% or less by weight, 2.5% or less by weight, 2% or less by weight, 1% or less by weight, 0.7% or less by weight, 0.5% or less by weight, or 0.3% or less by weight. Each of these ranges may be combined with one another.

[0231]

[0232] The weight ratio of the first additive and the second additive may be 1:1 to 40:1, specifically 1:1 to 20:1, more specifically 1:1 to 15:1, even more specifically 1:1 to 10:1, and even more specifically 2:1 to 7:1 in order to form a smooth reaction product of the first additive and the second additive.

[0233]

[0234] The above additive may further include an auxiliary additive together with the first additive and the second additive.

[0235] The above auxiliary additive may be included in the non-aqueous electrolyte to prevent the decomposition of the non-aqueous electrolyte in a high-power environment from causing cathode collapse, or to provide low-temperature high-rate discharge characteristics, high-temperature stability, prevention of overcharging, and suppression of battery expansion at high temperatures.

[0236] Specifically, the above auxiliary additive may include at least one selected from the group consisting of lithium difluorophosphate (LiDFP), vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, LiBOB (Lithium bis-(oxalato)borate), LiBF4 (Lithium tetrafluoroborate), LiDFOB (Lithium difluoro(oxalato)borate), LiDFOP (Lithium difluoro bis(oxalato) phosphate), TMSPa (Tris(trimethylsilyl) Phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite).

[0237] The above auxiliary additive may be included in the above non-aqueous electrolyte in an amount of 0.1% to 15% by weight, more specifically 0.3% to 5% by weight.

[0238]

[0239] lithium secondary battery

[0240] In addition, the present invention provides a lithium secondary battery comprising the aforementioned non-aqueous electrolyte.

[0241] Specifically, the lithium secondary battery according to the present invention comprises a negative electrode; a positive electrode facing the negative electrode; a separator interposed between the negative electrode and the positive electrode; and the aforementioned non-aqueous electrolyte.

[0242] The above lithium secondary battery can be manufactured by housing an electrode assembly comprising the above negative electrode; a positive electrode facing the above negative electrode; and a separator interposed between the above negative electrode and the positive electrode in a battery case, and then injecting the aforementioned non-aqueous electrolyte.

[0243]

[0244] As the non-aqueous electrolyte has been described above, the cathode, anode, and separator will be described below.

[0245]

[0246] (1) Cathode

[0247] The above cathode can be opposite to the above anode.

[0248] The above cathode includes a cathode active material.

[0249] The above-mentioned negative electrode active material is a material capable of reversibly inserting / extracting lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, (quasi)metal-based active materials, and lithium metal, and specifically may include at least one selected from carbon-based active materials and (quasi)metal-based active materials. The above-mentioned negative electrode active material may include at least one selected from the group consisting of carbon-based active materials and silicon-based active materials.

[0250] The above carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include at least one selected from the group consisting of artificial graphite and natural graphite.

[0251] Average particle size (D of the above carbon-based active material) 50) can be 10㎛ to 30㎛, preferably 15㎛ to 25㎛, in terms of ensuring structural stability during charging and discharging and reducing adverse reactions with the electrolyte.

[0252] Specifically, the above (quasi)metallic active material may include at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium with at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); lithium vanadium oxide; etc.

[0253] More specifically, the above (quasi)metallic active material may include a silicon-based active material.

[0254] The above silicon-based active material is silicon (Si) and silicon oxide (SiO₂). x (0 <x<2)로 표시될 수 있음) 및 실리콘-탄소 복합체(Si / C Composite)로 이루어진 군에서 선택된 적어도 1종을 포함할 수 있다.

[0255] Average particle size (D) of the above silicon-based active material 50 ) can be 1㎛ to 30㎛, preferably 2㎛ to 15㎛, in terms of reducing adverse reactions with the electrolyte while ensuring structural stability during charging and discharging.

[0256]

[0257] The above cathode may include a cathode current collector; and a cathode active material layer disposed on at least one surface of the cathode current collector. In this case, the cathode active material may be included in the cathode active material layer.

[0258] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the above-mentioned negative current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy.

[0259] The above-mentioned cathode current collector can typically have a thickness of 3 to 500 μm.

[0260] The above-mentioned negative current collector may form fine irregularities on its surface to strengthen the bonding force of the negative active material. For example, the above-mentioned negative current collector can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0261]

[0262] The above negative electrode active material layer may be disposed on at least one surface of the negative electrode current collector, specifically on one or both surfaces of the negative electrode current collector.

[0263] The above-mentioned negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight, preferably 75% to 95% by weight.

[0264] The explanation regarding other positive active materials has been previously provided and will be omitted.

[0265] The above cathode active material layer may further include a binder and / or a conductive material together with the cathode active material.

[0266] The binder is used to improve the performance of the battery by enhancing the adhesion between the negative electrode active material layer and the negative electrode current collector, and may include, for example, at least one selected from the group consisting of polyvinylidenefluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidenefluoride (PVDF), polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, and materials in which hydrogens thereof are substituted with Li, Na, or Ca, etc., and may also include various copolymers thereof. there is.

[0267] The above binder may be included in the cathode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0268] The above conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, Farnes 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; conductive materials such as polyphenylene derivatives may be used.

[0269] The above conductive material may be included in the above negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0270] The thickness of the above negative electrode active material layer may be 10㎛ to 200㎛, preferably 20㎛ to 150㎛.

[0271] The above cathode can be manufactured by coating a cathode slurry comprising a cathode active material, a binder, a conductive material, and / or a solvent for forming a cathode slurry on at least one surface of a cathode current collector, and then drying and rolling.

[0272] The solvent for forming the cathode slurry may include, for example, at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the cathode active material, binder, and / or conductive material. The solid content of the cathode slurry may be 30% to 80% by weight, specifically 40% to 70% by weight.

[0273]

[0274] (2) bipolar

[0275] The above anode may include an anode active material.

[0276] The above-mentioned cathode active material is a compound capable of reversible intercalation and deintercalation, and is not particularly limited as long as it is a cathode active material used in the field. Specifically, the above-mentioned cathode active material is a layered compound such as lithium cobalt oxide (LiCoO2) or lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; lithium iron phosphate such as LiFePO4; and a compound with the chemical formula Li 1+c1 Mn 2-c1Lithium manganese oxides such as O4 (0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2, etc.; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7, etc.; 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, satisfying 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxides represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn and Ta, satisfying 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); etc., but are not limited to these. The anode may also be a Li-metal anode.

[0277] More specifically, the positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), high-nickel lithium nickel-cobalt-manganese oxide, over-lithium manganese-rich oxide, and lithium iron phosphate.

[0278] The above high-nickel containing lithium nickel-cobalt-manganese oxide can be represented by the following chemical formula A.

[0279] [Chemical Formula A]

[0280] Li 1+x (Ni a Co b Mn c M d )O2

[0281] In the above chemical formula A, M is one or more 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 each atomic fractions of independent elements, where 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.

[0282] The above-mentioned lithium manganese-rich oxide may include a compound represented by the following chemical formula B.

[0283] [Chemical Formula B]

[0284] Li 1+s [Ni t Co u Mn v M 1 w ]O 2+z

[0285] In the above chemical formula B, M 1... is one or more 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 above 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 above formula B, 0.10≤s≤0.50, 0.1≤t≤0.5, 0≤u≤0.1, 0.6≤v<1.0, 0≤w≤0.1, and 0≤z≤0.50.

[0286] The above lithium iron phosphate may include a compound represented by the following chemical formula C.

[0287] [Chemical Formula C]

[0288] Li 1+e Fe 1-g M 2 g (PO 4-f )X f

[0289] In the above chemical formula C, 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 C can specifically be represented as LiFePO4 (g=0, e=0, and f=0).

[0290] The above positive electrode may include a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.

[0291] The above positive current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Specifically, the above positive current collector may include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy, preferably aluminum.

[0292] The thickness of the above positive current collector can typically be 3 to 500 μm.

[0293] The above positive current collector may form fine irregularities on its surface to strengthen the bonding force of the positive active material. For example, the above positive current collector can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0294] The positive active material layer may be disposed on at least one surface of the positive current collector. Specifically, the positive active material layer may be disposed on one or both surfaces of the positive current collector.

[0295] The above positive active material layer may include the aforementioned positive active material.

[0296] The above positive active material may be included in the above positive active material layer in an amount of 80% to 99% by weight, specifically 85% to 98% by weight.

[0297] The above positive active material layer may optionally further include a binder and / or a conductive material together with the aforementioned positive active material.

[0298] The above binder is a component that assists in the binding of active materials and conductive materials, and in binding to current collectors, and specifically may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene ter polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride.

[0299] The above binder may be included in the positive active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to sufficiently secure binding strength between components such as the positive active material.

[0300] The above conductive material can be used to assist and enhance conductivity in a secondary battery, and is not particularly limited as long as it is conductive without causing chemical changes. Specifically, the above cathode 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 carbon black, acetylene black, Ketjen black, channel black, Farnes 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 may include carbon nanotubes for the purpose of enhancing conductivity.

[0301] The above conductive material may be included in the above positive active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to sufficiently ensure electrical conductivity.

[0302] The thickness of the above positive active material layer may be 5㎛ to 500㎛, preferably 20㎛ to 200㎛.

[0303] The above anode can be manufactured by coating an anode slurry comprising an anode active material and optionally a binder, a conductive material, and a solvent for forming an anode slurry onto the above anode current collector, and then drying and rolling.

[0304]

[0305] (3) Separator

[0306] The above separator may be interposed between the anode and the cathode.

[0307] As the above separator, a conventional porous polymer film used as a separator, such as a polyolefin-based polymer film made of ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, may be used alone or in a laminate thereof, or a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc., may be used, but is not limited thereto. In addition, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0308]

[0309] The external shape of the lithium secondary battery of the present invention is not particularly limited, but can be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0310]

[0311] The present invention will be explained in more detail below through specific embodiments. However, the following embodiments are merely examples to aid in understanding the invention and do not limit the scope of the invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of this description, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0312]

[0313] Examples and Comparative Examples

[0314] Example 1

[0315] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0316] As an organic solvent, a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80 was used. LiPF6 was dissolved in the above organic solvent to a concentration of 1.2 M, and then a non-aqueous electrolyte was prepared by adding a compound represented by Formula 1-1 as a first additive and a compound represented by Formula 2-1-A1 as a second additive.

[0317] In the non-aqueous electrolyte, the first additive was added at 0.5% by weight and the second additive was added at 0.1% by weight.

[0318]

[0319] (Secondary battery manufacturing)

[0320] Anode active material (Li[Ni 0.6 Co 0.1 Mn 0.3 An anode slurry (solid content 30 wt%) was prepared by adding ]O2), a conductive material (carbon nanotubes), and a binder (polyvinylidene fluoride) in a weight ratio of 97.0:1.2:1.8. The anode slurry was applied to an anode current collector (Al thin film) and dried, then a roll press was performed to produce an anode.

[0321] A cathode slurry (solid content: 30 wt%) was prepared by adding a cathode active material (a mixture of graphite and a silicon-carbon composite in a weight ratio of 95:5), a binder (SBR-CMC), and a conductive material (carbon nanotubes) to water, a solvent, in a weight ratio of 96.84:3.15:0.01. The cathode slurry was coated onto a copper (Cu) thin film serving as a cathode current collector and dried, after which a roll press was performed to manufacture the cathode.

[0322] An electrode assembly was manufactured by interposing a porous separator polypropylene between the anode and cathode manufactured above, then housed in a battery case, and a lithium secondary battery was manufactured by injecting the electrolyte for the lithium secondary battery manufactured above.

[0323]

[0324] Example 2

[0325] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0326] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the first additive was added at 2% by weight in the non-aqueous electrolyte.

[0327]

[0328] (Secondary battery manufacturing)

[0329] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0330]

[0331] Example 3

[0332] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0333] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the first additive was added to the non-aqueous electrolyte at 0.1 wt%.

[0334]

[0335] (Secondary battery manufacturing)

[0336] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0337]

[0338] Example 4

[0339] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0340] A lithium secondary battery was manufactured in the same manner as in Example 1, except that 0.5% by weight of the second additive was added to the non-aqueous electrolyte.

[0341]

[0342] (Secondary battery manufacturing)

[0343] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0344]

[0345] Example 5

[0346] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0347] A lithium secondary battery was manufactured in the same manner as in Example 1, except that a second additive was added to the non-aqueous electrolyte at 0.05 wt%.

[0348]

[0349] (Secondary battery manufacturing)

[0350] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0351]

[0352] Comparative Example 1

[0353] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0354] A non-aqueous electrolyte for a lithium secondary battery was prepared in the same manner as in Example 1, except that the first additive and the second additive were not included in the non-aqueous electrolyte.

[0355]

[0356] (Secondary battery manufacturing)

[0357] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0358]

[0359] Comparative Example 2

[0360] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0361] A non-aqueous electrolyte for a lithium secondary battery was prepared in the same manner as in Example 1, except that the first additive was not included in the non-aqueous electrolyte.

[0362]

[0363] (Secondary battery manufacturing)

[0364] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0365]

[0366] Comparative Example 3

[0367] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0368] A non-aqueous electrolyte for a lithium secondary battery was prepared in the same manner as in Example 1, except that the second additive was not included in the non-aqueous electrolyte.

[0369]

[0370] (Secondary battery manufacturing)

[0371] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0372]

[0373] Comparative Example 4

[0374] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0375] A non-aqueous electrolyte for a lithium secondary battery was prepared in the same manner as in Example 1, except that the first additive was not included in the non-aqueous electrolyte and ethylene sulfate was included in the non-aqueous electrolyte at 0.5 wt%.

[0376]

[0377] (Secondary battery manufacturing)

[0378] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0379]

[0380] Comparative Example 5

[0381] (Manufacture of non-aqueous electrolytes for lithium secondary batteries)

[0382] A non-aqueous electrolyte for a lithium secondary battery was prepared in the same manner as in Example 1, except that the first additive was not included in the non-aqueous electrolyte and that a compound represented by the following chemical formula C-1 was included in the non-aqueous electrolyte at 0.5 wt%.

[0383] [Chemical Formula C-1]

[0384]

[0385]

[0386] (Secondary battery manufacturing)

[0387] A lithium secondary battery was manufactured using the same method as in Example 1, except that the non-aqueous electrolyte for a lithium secondary battery manufactured above was used.

[0388]

[0389] Experimental Example 1. Evaluation of High-Temperature Cycle Characteristics

[0390] The lithium secondary batteries of the examples and comparative examples prepared above were charged to 4.4V and 0.05C at 45℃ under CC / CV and 0.33C conditions using an electrochemical charge / discharger, and then discharged to 2.5V under CC and 0.33C conditions, with 400 charge / discharge cycles performed as one cycle.

[0391]

[0392] (1) Evaluation of capacity retention rate

[0393] The capacity retention rate was calculated using the formula below, and the results are shown in Table 1 below.

[0394]

[0395] Capacity Retention Rate (%) = {(Discharge Capacity after 400 Cycles) / (Discharge Capacity after 1 Cycle)} × 100

[0396]

[0397] (2) Evaluation of resistance growth rate

[0398] After one cycle of charging and discharging, the discharge capacity after one cycle was measured using an electrochemical charge / discharger, and the SOC was adjusted to 50%. Then, a pulse of 2.5C was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse application.

[0399] After 400 cycles of charging and discharging, the resistance after 400 cycles was calculated using the same method as above, and the resistance increase rate was calculated. The results are shown in Table 1 below.

[0400]

[0401] Resistance increase rate (%) = {(Resistance after 400 cycles - Resistance after 1 cycle) / Resistance after 1 cycle)} × 100 =

[0402]

[0403] (3) Evaluation of gas generation amount

[0404] After 400 cycles of charge and discharge, the amount of gas generated was measured using gas chromatography-mass spectrometry (GC-MS).

[0405]

[0406] Capacity Retention Rate (%) Resistance Increase Rate (%) Gas Generation Amount (μL) Example 1: 90 31 1893 Example 2: 87 34 2017 Example 3: 84 39 2342 Example 4: 89 36 2324 Example 5: 86 331965 Comparative Example 1: 157 835 302 Comparative Example 2: 637 54513 Comparative Example 3: 72 46 2850 Comparative Example 4: 75 49 2934 Comparative Example 5: 76 46 3152

[0407]

[0408] Referring to Table 1, it can be seen that the lithium secondary batteries of the embodiments using the non-aqueous electrolyte according to the present invention have significantly improved cycle charge / discharge performance at high temperatures compared to the comparative example.

[0409]

[0410] Experimental Example 2. Evaluation of High-Temperature Storage Characteristics

[0411] The lithium secondary batteries of the examples and comparative examples prepared above were charged to 4.4V and 0.05C at 25°C under CC / CV and 0.33C conditions and discharged to 2.5V at CC and 0.33C conditions to perform initial charge and discharge, and then charged to 4.4V and 0.05C at 25°C under CC / CV and 0.33C conditions, and then stored at 60°C for 16 weeks.

[0412]

[0413] (1) Evaluation of capacity retention rate

[0414] After storage, the above secondary batteries were charged to 4.4V and 0.05C at 25℃ under CC / CV and 0.33C conditions, and discharged to 2.5V at CC and 0.33C. The capacity retention rate was evaluated according to the following formula, and the results are shown in Table 2 below.

[0415]

[0416] Capacity Retention Rate (%) = (Discharge Capacity after 16 Weeks of Storage / Initial Discharge Capacity) × 100

[0417]

[0418] (2) Evaluation of resistance growth rate

[0419] During the initial charge / discharge, the capacity was checked at room temperature, charged to SOC 50 based on the discharge capacity, and discharged for 10 seconds with a current of 2.5C. The resistance was measured using the difference in voltage drop at that time and set as the initial resistance. After storing at 60℃ for 16 weeks, the resistance was measured in the same way and set as the final resistance. The resistance increase rate was then calculated using the following formula. The results are shown in Table 2 below.

[0420]

[0421] Resistance Increase Rate (%) = (Final Resistance - Initial Resistance) / (Initial Resistance) × 100

[0422]

[0423] (3) Evaluation of gas generation amount

[0424] After storage under the above conditions, the amount of gas generated was measured using gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 2 below.

[0425]

[0426] Capacity Retention Rate (%) Resistance Increase Rate (%) Gas Generation Amount (μL) Example 19 325 2603 Example 28 8 323 127 Example 38 139 3652 Example 49 131 3374 Example 58 9 29 2879 Comparative Example 15 6 74 6732 Comparative Example 26 35 95 926 Comparative Example 37 5 44 4983 Comparative Example 47 9 45 5135 Comparative Example 57 7 43 45 95

[0427]

[0428] Referring to Table 2, it can be seen that the lithium secondary batteries of the embodiments using the non-aqueous electrolyte according to the present invention have significantly improved storage performance at high temperatures compared to the comparative example.

Claims

1. Contains a lithium salt, an organic solvent, and additives, The above additive includes a first additive and a second additive, and The first additive comprises a compound in which two cyclic sulfates are directly bonded or bonded through a linker, and The second additive above is a non-aqueous electrolyte comprising a nitrogen-containing heteroaromatic compound substituted with at least one of a vinyl group and a proparzyl group.

2. In Claim 1, The above first additive is a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] R a -L a -R L -L b -R b In the above chemical formula 1, R a and R b The are independently selected from the following chemical formulas R-1 to R-3, and L a and L b are independently directly bonded or are alkylene groups having 1 to 5 carbon atoms, and R L It is selected from direct bonds, alkylene groups having 1 to 5 carbon atoms, and substituents represented by the following formulas L-1 to L-7. [Chemical Formula R-1] [Chemical Formula R-2] [Chemical Formula R-3] [Chemical Formula L-1] [Chemical Formula L-2] [Chemical Formula L-3] [Chemical Formula L-4] [Chemical Formula L-5] [Chemical Formula L-6] [Chemical Formula L-7] In the above chemical formulas R-1 to R-3 and L-1 to L-7, * is a binding site, and R L1 and R L2 The groups are independently selected from hydrogen, fluorine (F), and alkyl groups having 1 to 3 carbon atoms.

3. In Claim 2, A non-aqueous electrolyte comprising at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-4, wherein the compound represented by the above chemical formula 1: [Chemical Formula 1-1] [Chemical Formula 1-2] [Chemical Formula 1-3] [Chemical Formula 1-4] .

4. In Claim 1, The above second additive is a non-aqueous electrolyte comprising at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1 and 2-2: [Chemical Formula 2-1] In the above chemical formula 2-1, Y 11 is nitrogen (N) or R Y11 is the substituted carbon (C), and Y 12 is oxygen (O), sulfur (S), R Y121 nitrogen (N) or R substituted Y122 and R Y123 is the substituted carbon (C), and Y 13 is nitrogen (N) or R Y13 is the substituted carbon (C), and Y 14 is nitrogen (N) or R Y14 is the substituted carbon (C), and Y 15 is nitrogen (N) or R Y15 is the substituted carbon (C), and here, Y 11 and Y 15 At least one of them is nitrogen (N), and Y 11 , Y 12 , Y 13 , Y 14 , and Y 15 At least one of them is carbon (C), and R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 At least one of them is a substituent represented by the above chemical formula 2-a, and [Chemical Formula 2-2] In the above chemical formula 2-2, Y 21 is nitrogen (N) or R Y21 is the substituted carbon (C), and Y 22 is nitrogen (N) or R Y22 is the substituted carbon (C), and Y 23 is nitrogen (N) or R Y23 is the substituted carbon (C), and Y 24 is nitrogen (N) or R Y24 is the substituted carbon (C), and Y 25 is nitrogen (N) or R Y25 is the substituted carbon (C), and in this case, Y 21 , Y 22 , Y 23 , Y 24 and Y 25 At least one of them is carbon (C), and R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is independently selected from hydrogen, an alkyl group having 1 to 3 carbon atoms, and a substituent represented by the following chemical formula 2-a, wherein R Y21 , R Y22 , R Y23 , R Y24 and R Y25 At least one of them is a substituent represented by the above chemical formula 2-a, and [Chemical Formula 2-a] In the above chemical formula 2-a, L Y1 is selected from direct bonds, esters, ethers, and alkylene groups having 1 to 5 carbon atoms, and R Y1 is a directly bonded or C1 to C5 alkylene group, and R Y2 It is *-CH=CH2 or *-C≡CH, where * is the bonding site.

5. In Claim 4, A non-aqueous electrolyte comprising at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1, 2-1-B, 2-1-C, 2-1-D, 2-1-E, and 2-1-F: [Chemical Formula 2-1-A] [Chemical Formula 2-1-B] [Chemical Formula 2-1-C] [Chemical Formula 2-1-D] [Chemical Formula 2-1-E] [Chemical Formula 2-1-F] In the above chemical formulas 2-1-A, 2-1-B, 2-1-C, 2-1-D, 2-1-E, and 2-1-F, R Y11 , R Y121 , R Y122 , R Y123 , R Y13 , R Y14 and R Y15 is as defined in Chemical Formula 2-1.

6. In Claim 4, A non-aqueous electrolyte comprising at least one selected from the group consisting of compounds represented by the following chemical formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D, and 2-2-E: [Chemical Formula 2-2-A] [Chemical Formula 2-2-B] [Chemical Formula 2-2-C] [Chemical Formula 2-2-D] [Chemical Formula 2-2-E] In the above chemical formulas 2-2-A, 2-2-B, 2-2-C, 2-2-D, and 2-2-E, R Y21 , R Y22 , R Y23 , R Y24 and R Y25 is as defined in Chemical Formula 2-2.

7. In Claim 1, The above second additive is a non-aqueous electrolyte comprising at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1-A1 to 2-1-A4: [Chemical Formula 2-1-A1] [Chemical Formula 2-1-A2] [Chemical Formula 2-1-A3] [Chemical Formula 2-1-A4] .

8. In Claim 1, The first additive is a non-aqueous electrolyte included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight.

9. In Claim 1, The second additive is a non-aqueous electrolyte included in the non-aqueous electrolyte in an amount of 0.001% to 10% by weight.

10. In Claim 1, A non-aqueous electrolyte in which the weight ratio of the first additive and the second additive is 1:1 to 40:

1.

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

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