Nonaqueous electrolyte and lithium secondary battery comprising same

Abstract

The present invention relates to a nonaqueous electrolyte and a lithium secondary battery comprising same. The nonaqueous electrolyte according to the present invention comprises a lithium salt, a nonaqueous electrolyte, and an additive, wherein the additive may comprise a compound represented by chemical formula 1.

Description

Non-aqueous electrolyte and lithium secondary battery containing the same

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

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0153869 filed November 1, 2024 and Korean Patent Application No. 10-2025-0157235 filed October 27, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of this specification.

[0003]

[0004] Technology field

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

[0006] As dependence on electrical energy gradually increases in modern society, the development of large-capacity power storage devices capable of stably supplying power while simultaneously increasing production is emerging. Furthermore, the need for high-capacity portable power is growing due to the performance improvements of electronic products, ranging from small devices such as mobile phones to medium-to-large devices such as electric vehicles. Lithium-ion batteries, which possess the highest potential, satisfy high-capacity power storage performance requirements and are therefore being utilized in a wide range of applications, from small electronic devices to electric vehicles (EVs) and energy storage systems (ESS).

[0007] The above lithium secondary battery generally consists of a positive electrode containing a positive active material, a negative electrode containing a negative active material, an electrolyte serving as a medium for transporting lithium ions, and a separator. In this case, carbon-based active materials, silicon-based active materials, lithium transition metal oxides, lithium metal, etc., may be used as the negative electrode active material. Additionally, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel-cobalt-manganese composite oxide, and lithium iron phosphate may be used as the positive electrode active material.

[0008] During the charging of a lithium secondary battery, lithium ions are generated from the positive electrode and can be converted into stacked or alloyed forms for storage on the negative electrode, while discharge proceeds in the opposite direction. Theoretically, the movement of lithium ions to the positive and negative electrodes during charging and discharging of such lithium secondary batteries should be reversible; however, in reality, the movement of lithium within the battery may be partially irreversible. Specifically, the medium through which lithium ions can move is the electrolyte. During charging, most lithium ions are stacked or alloyed within the negative electrode active material, but some are reduced together with the organic and inorganic materials constituting the electrolyte to form nano-sized organic-inorganic composites on the surface of the negative electrode material. This formed organic-inorganic film is called a solid electrolyte interface layer (SEI layer). Meanwhile, a solid electrolyte interface layer can also be formed on the surface of the positive electrode active material through the oxidation reaction of the materials constituting the electrolyte.

[0009] While such a solid-electrolyte interface layer causes irreversible permanent loss of lithium ions supplied by the anode during formation, once formed, this irreversible loss is reduced, and a wide driving potential of the electrolyte is secured, enabling smooth reversible movement of lithium ions between the anode and cathode. Depending on its internal composition, this solid-electrolyte interface layer can contribute to lowering the energy barrier required for charge transfer of lithium ions to the cathode or anode, or its stability can determine the lifespan characteristics and durability of the lithium secondary battery.

[0010] Meanwhile, as the application range of lithium secondary batteries expands to include not only portable power sources such as mobile phones, laptop computers, digital cameras, and camcorders, but also medium and large power sources such as power tools, electric bicycles, hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), high driving voltages are required to achieve high energy density.

[0011] However, when operating continuously under high voltage, not only is the electrolyte depleted due to oxidative decomposition reactions between the anode and the electrolyte, but the breakdown of the passivation film on the electrode surface also leads to problems such as gas generation from side reactions in the electrolyte and the leaching of transition metals from the anode, resulting in a deterioration of the battery's long-life performance. These problems are exacerbated or accelerated by exothermic reactions generated during battery operation.

[0012] Accordingly, strengthening the stability of the solid-electrolyte interface layer formed on the surfaces of the anode and cathode is emerging as an important challenge to improve the high-voltage driving performance of lithium secondary batteries.

[0013] The present invention aims to solve the above-mentioned problems by providing a non-aqueous electrolyte capable of increasing the stability of the solid-electrolyte interface layer formed at the cathode and the anode.

[0014] In addition, the present invention provides a lithium secondary battery with improved high-temperature durability by including the above-mentioned non-aqueous electrolyte.

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

[0016] [Chemical Formula 1]

[0017]

[0018] (In the above chemical formula 1,

[0019] R1 and R2 are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms).

[0020] [2] The present invention provides a non-aqueous electrolyte in which, in [1], R1 and R2 in Formula 1 are each independently hydrogen or an alkyl group having 1 to 3 carbon atoms.

[0021] [3] The present invention provides a non-aqueous electrolyte in which, in [1] or [2], the compound represented by Formula 1 is selected from the group consisting of at least one compound represented by Formulas 1A to 1D below.

[0022] [Chemical Formula 1A]

[0023]

[0024] [Chemical Formula 1B]

[0025]

[0026] [Chemical Formula 1C]

[0027]

[0028] [Chemical Formula 1D]

[0029]

[0030] [4] The present invention provides a non-aqueous electrolyte in which, in at least one of [1] to [3], the compound represented by Formula 1 is included in an amount of 0.01% to 13.0% by weight based on the total weight of the non-aqueous electrolyte.

[0031] [5] The present invention provides a non-aqueous electrolyte in which, in at least one of [1] to [4], the compound represented by Formula 1 is included in an amount of 0.01% to 5.0% by weight based on the total weight of the non-aqueous electrolyte.

[0032] [6] The present invention provides a non-aqueous electrolyte, wherein, in at least one of [1] to [5], the additive further comprises a lithium salt-based compound.

[0033] [7] The present invention provides a non-aqueous electrolyte in which the lithium salt compound of [6] is selected from the group consisting of lithium bis-oxalatoborate (LiB(C2O4)2, LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiPO2F2, LiDFP) and lithium difluoro(bis-oxalato)phosphate (LiDFOP).

[0034] [8] The present invention provides a non-aqueous electrolyte in which, in [6] or [7], the lithium salt compound is included in an amount of 0.01% to 10.0% by weight based on the total weight of the non-aqueous electrolyte.

[0035] [9] The present invention provides a non-aqueous electrolyte in which, in at least one of [1] to [8], the non-aqueous electrolyte further comprises at least one auxiliary additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, and silane compounds.

[0036]

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

[0037] The non-aqueous electrolyte according to the present invention can form a durable inorganic film on the surface of the positive and negative electrodes by including a selenium-based compound as an additive. When this non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, the structural stability of the positive electrode under high voltage conditions can be increased, and side reactions between the negative electrode and the electrolyte can be suppressed, thereby improving high-temperature durability.

[0038] The terms and words used in this specification and claims are used merely to describe exemplary embodiments and should not be interpreted as being limited to their ordinary or dictionary meanings, and 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.

[0039] For example, in this specification, terms such as “comprising,” “having,” 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.

[0040] In addition, in the description of “carbon number a to b” 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, “alkylene group having 1 to 5 carbon atoms” refers to an alkylene group containing carbon atoms having 1 to 5 carbon atoms, namely -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH2CH2CH2CH2CH2-, and -CH(CH3)CH2CH2-, etc.

[0041] Additionally, in this specification, the term “alkylene group” means a branched or unbranched aliphatic hydrocarbon group or a functional group in which one hydrogen atom is removed from each carbon atom located at both ends of the aliphatic hydrocarbon group. In one embodiment, the alkylene group may be substituted or unsubstituted. The alkylene group includes, but is not limited to, methylene groups, ethylene groups, propylene groups, isopropylene groups, butylene groups, isobutylene groups, tert-butylene groups, pentylene groups, 3-pentylene groups, etc., and each of these may be optionally substituted in other embodiments.

[0042] Additionally, in this specification, “substitution” means that at least one hydrogen bonded to carbon is substituted with another element, such as fluorine, unless otherwise defined.

[0043] Additionally, in this specification, “*” refers to a connected portion between the terminals of a chemical formula unless otherwise defined.

[0044] Additionally, in this specification, “%” means weight % unless otherwise explicitly indicated.

[0045] The present invention will be described in detail below.

[0046] The non-aqueous electrolyte and lithium secondary battery according to the present invention comprise at least one of the configurations disclosed below, and may comprise any combination of technically feasible configurations among the configurations below.

[0047] Non-aqueous electrolytes

[0048] The present invention relates to a non-aqueous electrolyte, and more specifically, to a non-aqueous electrolyte for a lithium secondary battery.

[0049] Specifically, the non-aqueous electrolyte of the present invention comprises a lithium salt; a non-aqueous organic solvent and an additive, wherein the additive may comprise a compound represented by the following chemical formula 1.

[0050] [Chemical Formula 1]

[0051]

[0052] (In the above chemical formula 1,

[0053] R1 and R2 are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms).

[0054]

[0055] The non-aqueous electrolyte according to the present invention comprises a selenium-based compound substituted with nitrogen dioxide (NO2) as an additive, thereby enabling the formation of a durable inorganic film on the surfaces of the anode and cathode. Therefore, when this non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, high voltage and high temperature durability can be improved.

[0056]

[0057] (1) Lithium salt

[0058] 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, Li as a cation + It includes, and as anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO4 - , 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 - and CF3(CF2)7SO3 - At least one selected from the group consisting of can be cited.

[0059] Specifically, the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 It may include a single substance selected from the group consisting of LiAlCl4, LiAlO4, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2(Lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF2CF3)2(lithium bis(pentafluoroethanesulfonyl)imide, LiBETI), and LiN(SO2CF3)2(lithium bis(trifluoromethanesulfonyl)imide, LiTFSI), or a mixture of two or more substances. 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).

[0060] The above lithium salt can be appropriately modified within a range that is typically usable, but in order to obtain the effect of forming a corrosion-preventing film on the optimal electrode surface, it may be included in the electrolyte at a concentration of 0.8M to 4.0M, specifically at a concentration of 1.0M to 3.0M.

[0061] When the concentration of the above lithium salt is included within the above range, the viscosity of the non-aqueous electrolyte can be controlled to achieve optimal impregnation, and the mobility of lithium ions can be improved to obtain the effect of improving the capacity characteristics and cycle characteristics of the lithium secondary battery.

[0062]

[0063] (2) Non-aqueous organic solvent

[0064] The above-mentioned non-aqueous 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.

[0065] The above-mentioned non-aqueous organic solvent may be included in the non-aqueous electrolyte in the remainder excluding lithium salts and additives, for example.

[0066] Specifically, the above-mentioned non-aqueous organic solvent may include a carbonate-based organic solvent. Specifically, the carbonate-based organic solvent may include at least one selected from (i) a cyclic carbonate-based organic solvent and (ii) a linear carbonate-based organic solvent, and more specifically, may include (iii) a mixed solvent of a cyclic carbonate-based organic solvent and a linear carbonate-based organic solvent.

[0067] The above (i) cyclic carbonate-based organic solvent is a high-viscosity organic solvent that has a high dielectric constant and effectively dissociates lithium salts in a non-aqueous electrolyte, and may include at least one organic solvent 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 as specific examples, and may include at least one of ethylene carbonate and propylene carbonate.

[0068] The above (ii) linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may include at least one 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 as specific examples, and specifically may include one of dimethyl carbonate and ethyl methyl carbonate.

[0069] In order to secure a higher ionic conductivity, the non-aqueous electrolyte of the present invention may use (iii) the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent in combination, in which case the cyclic carbonate-based organic solvent and the linear carbonate-based organic solvent may be mixed in a volume ratio of 10:90 to 50:50, specifically 20:80 to 40:60.

[0070] In addition, the non-aqueous electrolyte of the present invention may further include at least one organic solvent among (iv) a linear ester-based organic solvent and (v) a cyclic ester-based organic solvent, which has a lower melting point and higher stability at high temperatures compared to the cyclic carbonate-based organic solvent and / or the linear carbonate-based organic solvent, together with the carbonate-based organic solvent.

[0071] The above (iv) linear ester-based organic solvent may include, as a representative 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, and specifically may include at least one of ethyl propionate and propyl propionate.

[0072] The above (v) cyclic ester-based organic solvent may include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0073] Meanwhile, the above organic solvent may consist solely of the carbonate-based organic solvent. Even if only the carbonate-based organic solvent is used as the organic solvent, it is preferable in that it facilitates the dissolution of non-aqueous electrolyte components, such as the additives described later, and enables the realization of appropriate mobility of the lithium salt and viscosity of the non-aqueous electrolyte.

[0074] Meanwhile, the remainder of the non-aqueous electrolyte of the present invention, excluding the lithium salt, electrolyte additive, and auxiliary additives described below, may all be organic solvents unless otherwise noted.

[0075]

[0076] (3) Additives

[0077] The non-aqueous electrolyte of the present invention may include a compound represented by the following chemical formula 1 as an additive.

[0078] [Chemical Formula 1]

[0079]

[0080] (In the above chemical formula 1,

[0081] R1 and R2 are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms).

[0082] The compound represented by Chemical Formula 1 above is a 1,3,2-dioxaselenane-2-oxide compound substituted with a nitro group (-NO2). Since it contains a selenium (Se) element with strong interaction with metals within a heterocyclic structure containing two or more oxygen elements, the electron density around the selenium element decreases, allowing the ring-opening reaction to easily occur around the selenium element. After the ring-opening reaction, a polymeric film containing some oxygen (O) with LiSe2 and SeO bonds can be formed on the anode surface through electrochemical reduction and recombination reactions. This improves the Li ion transport characteristics and prevents side reactions between the electrolyte and the anode, thereby effectively suppressing the leaching of transition metals from the anode. Therefore, by forming a film with superior Li ion migration characteristics compared to selenide compounds such as selenophen that do not contain oxygen in their structure, it is possible to obtain an effect of improved output characteristics resulting from reduced interfacial resistance and increased charge / discharge efficiency.

[0083] In addition, since the compound represented by Chemical Formula 1 has a nitro group (-NO2) substituted at the para- position of the selenium element, compared to 1,3,2-dioxaselenan-2-oxide, which does not contain a nitro group (-NO2) represented by Chemical Formula 4 below, or compounds in which a nitro group (-NO2) is substituted at the ortho- position of the selenium element, the electron configuration within the ring structure is symmetrically positioned, allowing it to participate more easily in film formation, thereby enabling the formation of a more robust nitrogen-containing inorganic film on the negative electrode surface. Consequently, the stability of the solid-electrolyte interface layer can be further enhanced, thereby preventing side reactions between the negative electrode and the electrolyte and preventing transition metal ions eluted from the anode from being electrodeposited on the negative electrode surface, thus enabling the manufacture of a lithium secondary battery with excellent high-temperature durability and minimized loss of reversible lithium ions.

[0084] [Chemical Formula 4]

[0085]

[0086] Meanwhile, in the above chemical formula 1, R1 may be hydrogen or an alkyl group having 1 to 3 carbon atoms, and specifically may be hydrogen or an alkyl group having 1 or 2 carbon atoms.

[0087] In the above chemical formula 1, R2 may be hydrogen or an alkyl group having 1 to 3 carbon atoms, and specifically may be hydrogen or an alkyl group having 1 or 2 carbon atoms.

[0088] Specifically, the compound represented by the above chemical formula 1 may be at least one selected from the group consisting of compounds represented by the following chemical formulas 1A to 1D.

[0089] [Chemical Formula 1A]

[0090]

[0091] [Chemical Formula 1B]

[0092]

[0093] [Chemical Formula 1C]

[0094]

[0095] [Chemical Formula 1D]

[0096] .

[0097] The compound represented by Chemical Formula 1 above may be included in an amount of 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, 0.09 wt% or more, or 1.0 wt% or more, based on the total weight of the non-aqueous electrolyte. Additionally, the compound represented by Chemical Formula 1 above may be included in an amount of 13 wt% or less, 12 wt% or less, 11 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, or 4 wt% or less, based on the total weight of the non-aqueous electrolyte.

[0098] The above ranges may be combined with one another without limitation. For example, the compound represented by Formula 1 may be included in an amount of 0.01 wt% to 13.0 wt% based on the total weight of the non-aqueous electrolyte, or in an amount of 0.01 wt% to 5.0 wt%, or in an amount of 0.1 wt% to 3.0 wt%.

[0099] When the compound represented by Chemical Formula 1 satisfies the above numerical range, a robust inorganic film containing lithium-selenium (LiSe2), selenium-oxygen (Se-O), and lithium-nitrogen (Li3N) bonds can be uniformly formed on the surfaces of the anode and cathode while minimizing disadvantages such as side reactions caused by additives, capacity reduction, and increased resistance. Accordingly, side reactions between the electrolyte and the electrode can be effectively suppressed, and the leaching of transition metals from the anode and the electrodeposition of transition metals on the cathode surface can be effectively suppressed, thereby enabling excellent high voltage and high temperature durability.

[0100] Meanwhile, the above additive may additionally include a lithium salt-based compound.

[0101] When the above lithium salt-based compound and the above selenium-based compound are used in combination, Li ions are smoothly supplied, making it possible to form a stable Li-based inorganic film on the surface of the cathode. In particular, since the anions of the lithium salt-based compound, like the selenium-based compound, form strong interactions with the surface of the anode and participate in the anode film formation reaction together with the selenium-based compound, a more robust film with improved coverage characteristics can be formed. Meanwhile, if the lithium salt-based compound is further included as an additive, the compound represented by Chemical Formula 1 may be named as the first additive, and the lithium salt-based compound may be named as the second additive.

[0102] These lithium salt-based compounds are compounds different from the lithium salt included in the electrolyte, and as representative examples, may include at least one selected from the group consisting of lithium bis-oxalatoborate (LiB(C2O4)2, LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiPO2F2, LiDFP), and lithium difluoro(bis-oxalato)phosphate (LiDFOP). Specifically, the lithium salt-based compound may include lithium difluorophosphate (LiPO2F2, LiDFP).

[0103] The above lithium salt-based compound may be included in an amount of 0.01 wt% or more, 0.02 wt% or more, 0.03 wt% or more, 0.04 wt% or more, 0.05 wt% or more, 0.06 wt% or more, 0.07 wt% or more, 0.08 wt% or more, 0.09 wt% or more, or 1.0 wt% or more, based on the total weight of the non-aqueous electrolyte. Additionally, the compound represented by Chemical Formula 1 may be included in an amount of 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, or 3 wt% or less, based on the total weight of the non-aqueous electrolyte.

[0104] The above ranges may be combined with one another without limitation. For example, the lithium salt-based compound may be included in an amount of 0.01 wt% to 10.0 wt% based on the total weight of the non-aqueous electrolyte, or in an amount of 0.01 wt% to 5.0 wt%, or in an amount of 0.1 wt% to 3.0 wt%.

[0105] When the content of the above lithium salt-based compound satisfies the above range, it is possible to form a stable Li-based inorganic film on the surfaces of the anode and cathode together with the above selenium-based compound, thereby effectively suppressing the leaching of oxygen or transition metals from the anode and preventing side reactions between the cathode and the electrolyte, thereby enabling excellent high voltage and high temperature durability.

[0106]

[0107] Meanwhile, the non-aqueous electrolyte of the present invention may additionally include auxiliary additives within the non-aqueous electrolyte as needed to prevent the decomposition of the electrolyte in a high-power environment from causing cathode collapse, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, prevention of overcharging, and suppression of battery expansion at high temperatures. If auxiliary additives are additionally included in the non-aqueous electrolyte, the compound represented by Chemical Formula 1 may be named as the first additive, and the auxiliary additive may be named as the second additive. Furthermore, if both the lithium salt-based compound and the auxiliary additive are included as electrolyte additives, the compound represented by Chemical Formula 1 may be named as the first additive, the lithium salt-based compound may be named as the second additive, and the auxiliary additive may be named as the third additive.

[0108] The above auxiliary additive may include at least one selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, and silane compounds, and the phosphate compounds and borate compounds may include compounds with different structures, excluding the lithium salt compounds described above.

[0109] Examples of the above-mentioned cyclic carbonate compounds include vinylene carbonate (VC) or vinylethylene carbonate.

[0110] Examples of the above halogen-substituted carbonate compounds include fluoroethylene carbonate (FEC).

[0111] The above sulfone-based compound may include at least one compound selected from the group consisting of 1,3-propane sulfone (PS), 1,4-butane sulfone, ethen sulfone, 1,3-propene sulfone (PRS), 1,4-butene sulfone, and 1-methyl-1,3-propene sulfone.

[0112] Examples of the above sulfate compounds include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0113] The above phosphate-based compounds may include one or more compounds selected from the group consisting of lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl)phosphate, tris(2,2,2-trifluoroethyl)phosphate, and tris(trifluoroethyl)phosphate.

[0114] Examples of the above borate-based compounds include tetraphenylborate.

[0115] The above nitrile-based compound may include at least one compound selected from the group consisting of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0116] Examples of the above benzene-based compounds include fluorobenzene, and examples of the above amine-based compounds include triethanolamine or ethylenediamine.

[0117] Tetravinylsilane can be cited as the above silane compound.

[0118] Among these auxiliary additives, if vinylene carbonate, vinylethylene carbonate, or succinonitrile is included, a more robust SEI film can be formed on the negative electrode surface during the initial activation process of the secondary battery.

[0119] Meanwhile, the above auxiliary additives may be used in a mixture of two or more types and may be included in an amount of 30% by weight or less, specifically 0.01 to 10.0% by weight, based on the total weight of the electrolyte, and preferably 0.05 to 5.0% by weight. If the content of the above auxiliary additive is less than 0.01% by weight, the effect of improving low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery is negligible, and if the content of the above auxiliary additive exceeds 30% by weight, there is a possibility that excessive side reactions may occur within the electrolyte during charging and discharging of the battery. In particular, when the above SEI film-forming additives are added in excess, they may not decompose sufficiently at high temperatures and may remain as unreacted substances or precipitated within the electrolyte at room temperature. Accordingly, side reactions that degrade the lifespan or resistance characteristics of the secondary battery may occur.

[0120]

[0121] lithium secondary battery

[0122] In addition, the present invention provides a lithium secondary battery comprising the aforementioned non-aqueous electrolyte.

[0123] Specifically, a lithium secondary battery according to the present invention may include a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The electrolyte may be the electrolyte for a lithium secondary battery of the present invention described above.

[0124] The above lithium secondary battery can be manufactured by housing an electrode assembly comprising a positive electrode, a negative electrode opposite to the positive electrode, and a separator interposed between the positive electrode and the negative electrode in a battery case, and then injecting the electrolyte for a lithium secondary battery according to the present invention as described above.

[0125] As the non-aqueous electrolyte has been described above, the anode, cathode, and separator will be described below.

[0126]

[0127] (1) positive electrode

[0128] The above anode may include an anode active material.

[0129] 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, it may include a lithium metal composite oxide. More specifically, the lithium metal composite oxide 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.

[0130] Specifically, the lithium metal composite oxide may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide, lithium manganese-rich oxide, and lithium iron phosphate, and most preferably may include lithium nickel cobalt manganese oxide.

[0131] The above lithium nickel-cobalt-manganese oxide can be represented by the following chemical formula 2.

[0132] [Chemical Formula 2]

[0133] Li 1+a Ni x Co y M 1 z M 2 w O2

[0134] In the above chemical formula 2,

[0135] M 1is Mn, Al, or a combination thereof, and

[0136] M 2 is at least one selected from the group consisting of Al, Zr, W, Ti, Mg, Ca, and Sr, and 0≤a≤0.5, 0.55 <x<1.0, 0<y≤0.4, 0<z≤0.4, 0≤w≤0.1 이다.

[0137] In this case, x+y+z+w can be 1.

[0138] In the above chemical formula 2, 1+a represents the molar ratio of lithium in the lithium nickel-cobalt-manganese composite oxide, and may be 0≤a≤0.5, preferably 0≤a≤0.2, more preferably 0≤a≤0.1.

[0139] In the above Chemical Formula 2, x represents the molar ratio of nickel among the total transition metals excluding lithium in the lithium nickel-cobalt-manganese composite oxide, 0.55 <x<1.0, 더욱 구체적으로는 0.6≤x≤0.98, 보다 더 구체적으로는 0.6≤x≤0.95일 수 있다.

[0140] In the above Chemical Formula 2, y represents the molar ratio of cobalt among the total transition metals excluding lithium in the lithium nickel-cobalt-manganese composite oxide, where 0 <y≤0.4, 구체적으로 0<y≤0.3, 더욱 구체적으로는 0.05≤y≤0.3일 수 있다.

[0141] In the above chemical formula 2, z is M among the total transition metals excluding lithium in the lithium nickel-cobalt-manganese composite oxide. 1 Representing the molar ratio of elements, 0 <z≤0.4, 바람직하게는 0<z≤0.3, 더 바람직하게는 0.01≤z≤0.3일 수 있다.

[0142] In the above chemical formula 2, w is M among the total transition metals excluding lithium in the lithium nickel-cobalt-manganese composite oxide. 2 Representing the molar ratio of elements, 0 <w≤0.1, 바람직하게는 0<w≤0.05, 더 바람직하게는 0<w≤0.02이다.

[0143] The above lithium nickel-cobalt-manganese oxide is Li(Ni with a Ni content of 0.55 atm% or more to realize a high-capacity battery. 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni) 0.7 Mn 0.15 Co 0.15 )O2, Li(Ni 0.7 Mn 0.2 Co 0.1 )O2, Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li(Ni 0.86 Mn 0.07 Co 0.05 Al 0.02 )O2, Li(Ni 0.90 Mn 0.05 Co 0.05 )O2 or Li(Ni 0.9 Mn 0.03 Co 0.06 Al 0.01 It can be )O2).

[0144] Meanwhile, the above-mentioned positive active material may be in the form of particles. Specifically, the average particle size (D) of the above-mentioned positive active material. 50 ) can be 1㎛ to 30㎛.

[0145] The above positive active material may be included in the positive active material layer in an amount of 70% to 99% by weight, specifically 80% to 98% by weight, for capacity enhancement.

[0146]

[0147] 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.

[0148] The above positive active material layer may include the aforementioned positive active material.

[0149] The thickness of the above positive current collector can typically be 3 to 500 μm.

[0150] 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.

[0151] The positive active material layer is 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.

[0152] The above-mentioned positive active material may be included in the positive active material layer in an amount of 70% to 99% by weight, specifically 80% to 98% by weight, taking into consideration the sufficient capacity exertion of the positive active material.

[0153] In addition, the positive active material layer may further include a binder and / or a conductive material together with the aforementioned positive active material.

[0154] The above binder serves to improve adhesion between positive active material particles and adhesion between the positive active material and the current collector. Examples of such binders include fluoropolymer-based binders comprising polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders comprising styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose-based binders comprising carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyalcohol-based binders comprising polyvinyl alcohol; polyolefin-based binders comprising polyethylene or polypropylene; polyimide-based binders; and polyester-based binders. One type of silane binder alone or a mixture of two or more types may be used.

[0155] The above binder may be included in an amount of 0.1 to 15.0 weight%, preferably 0.1 to 10.0 weight%, based on the total weight of the positive active material layer.

[0156] The above conductive material may be used to assist and improve 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 carbon black such as carbon black, acetylene black (or Denka black), Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; polyphenylene derivatives, etc., and one of these alone or a mixture of two or more may be used.

[0157] The above conductive material may be included in an amount of 0.1 to 10.0 weight%, preferably 0.1 to 5.0 weight%, based on the total weight of the positive active material layer.

[0158] The thickness of the above positive active material layer may be 5㎛ to 500㎛, preferably 20㎛ to 200㎛.

[0159] The anode may 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 anode current collector, and then drying and rolling. Alternatively, the anode may be manufactured by mixing an anode active material and optionally a binder, a conductive material, etc. to produce a film, and then laminating it onto an anode current collector.

[0160] The solvent for forming the anode slurry may include, for example, at least one selected from the group consisting of distilled water, N-methylpyrrolidone, ethanol, methanol, and isopropyl alcohol, preferably N-methylpyrrolidone, in order to facilitate the dispersion of the anode active material, binder, and / or conductive material. The amount of the solvent used is not particularly limited, provided that it is sufficient to allow the anode composite to have an appropriate viscosity, taking into account the coating thickness, manufacturing yield, workability, etc. of the anode composite.

[0161]

[0162] (2) Cathode

[0163] Next, the cathode is explained.

[0164] The above cathode may include a cathode active material.

[0165] The above 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.

[0166] The carbon-based active material may include at least one selected from the group consisting of graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably may include graphite. The graphite may be, for example, at least one of artificial graphite and natural graphite.

[0167] 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.

[0168] Specifically, the (quasi)metallic active material comprises: at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium and at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one (quasi)metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Fe, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); and lithium vanadium oxide. It may include the back.

[0169] More specifically, the above (quasi)metallic active material may include a silicon-based active material.

[0170] The above silicon-based active material is SiO x It may include at least one selected from the group consisting of compounds represented by (0≤x<2) and silicon-carbon composites. Since SiO2 does not react with lithium ions and therefore cannot store lithium, it is preferable that x be within the above range, and more preferably, the silicon-based active material may be SiO.

[0171] 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.

[0172] In addition, the negative electrode active material of the present invention may include a carbon-based negative electrode active material together with a silicon-based negative electrode active material.

[0173] At this time, the weight ratio of the silicon-based active material and the carbon-based active material may be 1:99 to 30:70, specifically 3:97 to 15:85. When the mixing ratio of the silicon-based active material and the carbon-based active material satisfies the above range, excellent cycle performance can be secured by suppressing the volume expansion of the silicon-based active material while improving capacity characteristics.

[0174]

[0175] Meanwhile, the above-mentioned 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.

[0176] 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.

[0177] The above-mentioned cathode current collector can typically have a thickness of 3 to 500 μm.

[0178] 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.

[0179] The above-mentioned negative electrode active material layer is disposed on at least one surface of the negative electrode current collector. Specifically, the negative electrode active material layer may be disposed on one or both surfaces of the negative electrode current collector.

[0180] The above negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight in order to sufficiently express capacity in the secondary battery while minimizing the effect of volume expansion / contraction on the battery.

[0181] The above cathode active material layer may further include a conductive material and / or a binder together with the cathode active material.

[0182] The above conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, preferably 5% by weight or less, specifically 0.1% to 5% by weight, based on the total weight of the negative electrode active material layer. Such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, carbon black such as carbon black, acetylene black (or Denka black), Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; polyphenylene derivatives, etc. may be used.

[0183] The above binder is a component that assists in the bonding between a conductive material, an active material, and a current collector, and specific examples include a fluoropolymer-based binder comprising polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); a rubber-based binder comprising styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; a cellulose-based binder comprising carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; a polyalcohol-based binder comprising polyvinyl alcohol; a polyolefin-based binder comprising polyethylene or polypropylene; a polyimide-based binder; a polyester-based binder; and a silane-based binder.

[0184] The above binder may be included in an amount of 0.1 to 15.0 weight%, preferably 0.1 to 10.0 weight%, based on the total weight of the negative electrode active material layer.

[0185] The thickness of the above negative electrode active material layer may be 5㎛ to 500㎛, preferably 5㎛ to 100㎛.

[0186] The above cathode may be manufactured by coating a cathode slurry comprising a cathode active material and optionally a binder, a conductive material, and a solvent for forming a cathode slurry onto the cathode current collector, and then drying and rolling. Alternatively, the cathode may be manufactured by mixing a cathode active material and optionally a binder, a conductive material, etc. to produce a film, and then laminating it onto a cathode current collector.

[0187] The solvent for forming the above cathode slurry may include, for example, at least one selected from the group consisting of distilled water, N-methylpyrrolidone, ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the cathode active material, binder, and / or conductive material.

[0188]

[0189] (3) Separator

[0190] The above separator separates the negative and positive electrodes and provides a pathway for the movement of lithium ions. It can be used without any specific restrictions as long as it is commonly used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of lithium salt ions while having excellent electrolyte moisture retention capacity.

[0191] Specifically, as a separator, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, 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.

[0192]

[0193] The lithium secondary battery according to the present invention as described above can be usefully applied in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0194] 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.

[0195] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0196]

[0197] Hereinafter, the present invention will be described in detail with reference to examples in order to specifically explain the invention. However, the embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the invention to those with average knowledge in the art.

[0198]

[0199] Examples

[0200] Example 1.

[0201] (Preparation of non-aqueous electrolytes)

[0202] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A as an electrolyte additive (see Table 1 below). The compound represented by Formula 1A was included in the non-aqueous electrolyte at a concentration of 0.01 wt%.

[0203]

[0204] (Secondary battery manufacturing)

[0205] Anode active material (Li(Ni) in solvent N-methyl-2-pyrrolidone (NMP) 0.8 Mn 0.1 Co 0.1An anode slurry (solid content 60.0 wt%) was prepared by adding O2), a conductive material (carbon black), and a binder (polyvinylidene fluoride) in a weight ratio of 97.6:0.8:1.6. The anode slurry was applied to an anode current collector (Al thin film) with a thickness of 13.5 μm and dried, then a roll press was performed to produce an anode.

[0206] A cathode slurry (solid content: 60 wt%) was prepared by adding a cathode active material (natural graphite), a binder (SBR-CMC), and a conductive material (carbon black) to water, a solvent, in a weight ratio of 97.6:0.8:1.6. The cathode slurry was applied to a 6 μm thick copper (Cu) thin film serving as a cathode current collector, dried, and then subjected to a roll press to manufacture the cathode.

[0207] An electrode assembly was manufactured by interposing a porous polypropylene separator between the anode and cathode manufactured above, then housing it in a battery case, and a lithium secondary battery was manufactured by injecting the non-aqueous electrolyte manufactured above.

[0208]

[0209] Example 2.

[0210] (Preparation of non-aqueous electrolytes)

[0211] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A as an electrolyte additive (see Table 1 below). The compound represented by Formula 1A was included in the non-aqueous electrolyte at 0.5 wt%.

[0212]

[0213] (Secondary battery manufacturing)

[0214] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0215]

[0216] Example 3.

[0217] (Preparation of non-aqueous electrolytes)

[0218] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A as an electrolyte additive (see Table 1 below). The compound represented by Formula 1A was included in the non-aqueous electrolyte at a concentration of 5 wt%.

[0219]

[0220] (Secondary battery manufacturing)

[0221] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0222]

[0223] Example 4.

[0224] (Preparation of non-aqueous electrolytes)

[0225] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A as an electrolyte additive (see Table 1 below). The compound represented by Formula 1A was included in the non-aqueous electrolyte at a concentration of 10 wt%.

[0226]

[0227] (Secondary battery manufacturing)

[0228] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0229]

[0230] Example 5.

[0231] (Preparation of non-aqueous electrolytes)

[0232] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1B as an electrolyte additive (see Table 1 below). The compound represented by Formula 1B was included in the non-aqueous electrolyte at a concentration of 5 wt%.

[0233]

[0234] (Secondary battery manufacturing)

[0235] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0236]

[0237] Example 6.

[0238] (Preparation of non-aqueous electrolytes)

[0239] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by the chemical formula 1C as an electrolyte additive (see Table 1 below). The compound represented by the chemical formula 1C was included in the non-aqueous electrolyte at a concentration of 5 wt%.

[0240]

[0241] (Secondary battery manufacturing)

[0242] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0243]

[0244] Example 7.

[0245] (Preparation of non-aqueous electrolytes)

[0246] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Chemical Formula 1D as an electrolyte additive (see Table 1 below). The compound represented by Chemical Formula 1D was included in the non-aqueous electrolyte at a concentration of 5 wt%.

[0247]

[0248] (Secondary battery manufacturing)

[0249] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0250]

[0251] Example 8.

[0252] (Preparation of non-aqueous electrolytes)

[0253] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 0.01 wt% and 0.01 wt%, respectively (see Table 1 below).

[0254]

[0255] (Secondary battery manufacturing)

[0256] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0257]

[0258] Example 9.

[0259] (Preparation of non-aqueous electrolytes)

[0260] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 10 wt% and 0.01 wt%, respectively (see Table 1 below).

[0261]

[0262] (Secondary battery manufacturing)

[0263] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0264]

[0265] Example 10.

[0266] (Preparation of non-aqueous electrolytes)

[0267] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 0.01 wt% and 10 wt%, respectively (see Table 1 below).

[0268]

[0269] (Secondary battery manufacturing)

[0270] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0271]

[0272] Example 11.

[0273] (Preparation of non-aqueous electrolytes)

[0274] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 10 wt% and 10 wt%, respectively (see Table 1 below).

[0275]

[0276] (Secondary battery manufacturing)

[0277] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0278]

[0279] Example 12.

[0280] (Preparation of non-aqueous electrolytes)

[0281] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0282]

[0283] (Secondary battery manufacturing)

[0284] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0285]

[0286] Example 13.

[0287] (Preparation of non-aqueous electrolytes)

[0288] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Chemical Formula 1A and lithium bisoxalate toborate (LiB(C2O4)2, LiBOB) as electrolyte additives. The compound represented by Chemical Formula 1A and lithium bisoxalate toborate (LiB(C2O4)2, LiBOB) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0289]

[0290] (Secondary battery manufacturing)

[0291] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0292]

[0293] Example 14.

[0294] (Preparation of non-aqueous electrolytes)

[0295] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1A and lithium difluoro(oxalato) borate (LiDFOB) as electrolyte additives. The compound represented by Formula 1A and lithium difluoro(oxalato) borate (LiDFOB) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0296]

[0297] (Secondary battery manufacturing)

[0298] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0299]

[0300] Example 15.

[0301] (Preparation of non-aqueous electrolytes)

[0302] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Formula 1A and lithium difluoro(bisoxalato) phosphate (LiDFOP) as electrolyte additives. The compound represented by Formula 1A and lithium difluoro(bisoxalato) phosphate (LiDFOP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0303]

[0304] (Secondary battery manufacturing)

[0305] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0306]

[0307] Example 16.

[0308] (Preparation of non-aqueous electrolytes)

[0309] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1B and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1B and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0310]

[0311] (Secondary battery manufacturing)

[0312] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0313]

[0314] Example 17.

[0315] (Preparation of non-aqueous electrolytes)

[0316] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1C and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1C and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0317]

[0318] (Secondary battery manufacturing)

[0319] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0320]

[0321] Example 18.

[0322] (Preparation of non-aqueous electrolytes)

[0323] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Formula 1D and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1D and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0324]

[0325] (Secondary battery manufacturing)

[0326] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0327]

[0328] Example 19.

[0329] (Preparation of non-aqueous electrolytes)

[0330] A non-aqueous electrolyte was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Formula 1A and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Formula 1A and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 15 wt% and 0.01 wt%, respectively (see Table 1 below).

[0331]

[0332] (Secondary battery manufacturing)

[0333] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0334]

[0335] Comparative Example 1.

[0336] (Preparation of non-aqueous electrolytes)

[0337] A non-aqueous electrolyte for lithium secondary batteries was prepared by dissolving LiPF6 in a non-aqueous organic solvent to a concentration of 1.2 M (see Table 1 below).

[0338]

[0339] (Secondary battery manufacturing)

[0340] A lithium secondary battery was manufactured in the same manner as in Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0341]

[0342] Comparative Example 2.

[0343] (Preparation of non-aqueous electrolytes)

[0344] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio to a concentration of 1.2 M, and then adding 1 wt% of LiDFP as an electrolyte additive (see Table 1 below).

[0345]

[0346] (Secondary battery manufacturing)

[0347] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0348]

[0349] Comparative Example 3.

[0350] (Preparation of non-aqueous electrolytes)

[0351] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio to a concentration of 1.2 M, and then adding 3 wt% of vinylene carbonate (VC) as an electrolyte additive (see Table 1 below).

[0352]

[0353] (Secondary battery manufacturing)

[0354] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0355]

[0356] Comparative Example 4.

[0357] (Preparation of non-aqueous electrolytes)

[0358] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding vinylene carbonate (VC) and LiDFP as electrolyte additives. The vinylene carbonate (VC) and LiDFP were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0359]

[0360] (Secondary battery manufacturing)

[0361] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0362]

[0363] Comparative Example 5.

[0364] (Preparation of non-aqueous electrolytes)

[0365] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding vinylene carbonate (VC) and lithium bisoxalate toborate (LiB(C2O4)2, LiBOB) as electrolyte additives. The vinylene carbonate (VC) and lithium bisoxalate toborate (LiBOB) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0366]

[0367] (Secondary battery manufacturing)

[0368] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0369]

[0370] Comparative Example 6.

[0371] (Preparation of non-aqueous electrolytes)

[0372] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding vinylene carbonate (VC) and lithium difluoro(oxalato) borate (LiDFOB) as electrolyte additives. The vinylene carbonate (VC) and lithium difluoro(oxalato) borate (LiDFOB) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0373]

[0374] (Secondary battery manufacturing)

[0375] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0376]

[0377] Comparative Example 7.

[0378] (Preparation of non-aqueous electrolytes)

[0379] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding vinylene carbonate (VC) and lithium difluoro(bisoxalato) phosphate (LiDFOP) as electrolyte additives. The vinylene carbonate (VC) and lithium difluoro(bisoxalato) phosphate (LiDFOP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0380]

[0381] (Secondary battery manufacturing)

[0382] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0383]

[0384] Comparative Example 8.

[0385] (Preparation of non-aqueous electrolytes)

[0386] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Chemical Formula 3 below and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Chemical Formula 3 and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0387] [Chemical Formula 3]

[0388]

[0389]

[0390] (Secondary battery manufacturing)

[0391] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0392]

[0393] Comparative Example 9.

[0394] (Preparation of non-aqueous electrolytes)

[0395] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 20:80 volume ratio, and then adding a compound represented by Chemical Formula 4 below and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Chemical Formula 4 and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0396] [Chemical Formula 4]

[0397]

[0398]

[0399] (Secondary battery manufacturing)

[0400] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0401]

[0402] Comparative Example 10.

[0403] (Preparation of non-aqueous electrolytes)

[0404] A non-aqueous electrolyte for a lithium secondary battery was prepared by dissolving LiPF6 to a concentration of 1.2 M in a non-aqueous organic solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 20:80, and then adding a compound represented by Chemical Formula 5 below and lithium difluorophosphate (LiDFP) as electrolyte additives. The compound represented by Chemical Formula 5 and lithium difluorophosphate (LiDFP) were included in the non-aqueous electrolyte at 3 wt% and 1 wt%, respectively (see Table 1 below).

[0405] [Chemical Formula 5]

[0406]

[0407]

[0408] (Secondary battery manufacturing)

[0409] A lithium secondary battery was manufactured in the same manner as Comparative Example 1, except that the above-manufactured non-aqueous electrolyte was injected.

[0410] Lithium Salt / Non-aqueous Organic Solvent 1st Additive 2nd Additive Chemical Formula Content (Wt%) Chemical Formula Content (Wt%) Example 1 1.2M LiPF6 / EC:EMC = 20 : 80 Volume Ratio 1A 0.01 -- Example 2 1A 0.5 -- Example 3 1A5 -- Example 4 1A10 -- Example 5 1B5 -- Example 6 1C5 -- Example 7 1D5 -- Example 8 1A 0.01 LiDFP 0.01 Example 9 1A 10 LiDFP 0.01 Example 10 1A 0.01 LiDFP 10 Example 11 1A 10 LiDFP 10 Example 12 1A 3 LiDFP 1 Example 13 1A 3 LiBOB 1 Example 14 1A 3 LiDFOB 1 Example 151A3LiDFOP1 Example 161B3LiDFP1 Example 171C3LiDFP1 Example 181D3LiDFP1 Example 191A15LiDFP0.01 Comparative Example 1----Comparative Example 2--LiDFP1 Comparative Example 3VC3--Comparative Example 4VC3LiDFP1 Comparative Example 5VC3LiBOB1 Comparative Example 6VC3LiDFOB1 Comparative Example 7VC3LiDFOP1 Comparative Example 833LiDFP1 Comparative Example 943LiDFP1 Comparative Example 1053LiDFP1

[0411] In Table 1 above, the abbreviations of the compounds each mean the following.

[0412] EC: Ethylene carbonate

[0413] EMC: Ethyl methyl carbonate

[0414] LiDPF: Lithium difluorophosphate

[0415] LiBOB: Lithium bisoxalate toborate

[0416] LiDFOB: Lithium difluoro(oxalato) borate

[0417] LiDFOP: Lithium difluoro(bisoxalato) phosphate

[0418] VC: Vinylene carbonate

[0419]

[0420] Experimental Example

[0421] Experimental Example 1. Evaluation of High-Temperature Cycle Characteristics

[0422] For the lithium secondary batteries prepared in the examples and comparative examples, an activation (formation) process was performed by charging at a rate of 0.1C for 3 hours, and then the batteries were fully charged to 100% SOC by charging at 25°C at a rate of 0.33C under constant current / constant voltage conditions up to 4.2V (0.05C cut-off). The fully charged batteries were charged at a high temperature (45°C) at a rate of 0.33C under constant current / constant voltage conditions up to 4.4V, and discharged at a rate of 0.33C under constant current conditions down to 2.5V; this constituted one cycle, and 400 th After performing the cycle, use Equation 1 below to 400 th The capacity retention rate after the cycle was calculated, and the results are shown in Table 2 below. In addition, through Equation 2 below, 400 th The resistance increase rate after the cycle was calculated, and the results are shown in Table 2 below.

[0423] [Equation 1]

[0424] Capacity retention rate (%) = (400 th Capacity after cycle / Capacity after 1 cycle) × 100

[0425]

[0426] [Equation 2]

[0427] Resistance increase rate (%) = {(400 th Resistance after cycle - Initial resistance) / Initial resistance} × 100

[0428]

[0429] 400 th Capacitance retention rate after cycle (%) Resistance increase rate (%) Example 18327 Example 28524 Example 38919 Example 48724 Example 58723 Example 68824 Example 78722 Example 88523 Example 98723 Example 108724 Example 118622 Example 128920 Example 138821 Example 148922 Example 158720 Example 168822 Example 178721 Example 188822 Example 197033 Comparative Example 15242 Comparative Example 25055 Comparative Example 35548 Comparative Example 45749 Comparative Example 55951 Comparative Example 65850 Comparative Example 76244 Comparative Example 85242 Comparative Example 96541 Comparative Example 105848

[0430]

[0431] Looking at Table 2 above, it can be seen that in the case of the secondary battery of the embodiment of the present invention, both the resistance increase rate (%) and the capacity retention rate (%) after high-temperature cycling are improved compared to the lithium secondary battery of the comparative example.

[0432]

[0433] Experimental Example 2. Evaluation of High-Temperature Storage Characteristics

[0434] For the lithium secondary batteries prepared in the examples and comparative examples, respectively, a formation process was performed by charging at a rate of 0.1C for 3 hours, and then the batteries were fully charged to 100% SOC by charging under constant current / constant voltage conditions (0.05C cut-off) at a rate of 0.33C to 4.4V at 25℃, and stored at a high temperature (60℃) for 20 weeks. Afterward, the batteries were discharged under constant current conditions at a rate of 0.33C to 2.5V, and the capacity retention rate after high-temperature storage was calculated using Equation 3 below, and the results are shown in Table 3 below. In addition, the batteries were transferred to a charge / discharger at room temperature (25℃) to measure the resistance, and the resistance increase rate after high-temperature storage was calculated using Equation 4 below, and the results are shown in Table 3 below.

[0435] [Equation 3]

[0436] Capacity retention rate (%) = (Capacity after high-temperature storage / Capacity after 1 cycle) × 100

[0437]

[0438] [Equation 4]

[0439] Resistance increase rate (%) = {(Resistance after high-temperature storage - Initial resistance) / Initial resistance} × 100

[0440] Capacity retention rate after high-temperature storage (%) Resistance increase rate (%) Example 18329 Example 28727 Example 39021 Example 48627 Example 59022 Example 68923 Example 78821 Example 88627 Example 98526 Example 108626 Example 118725 Example 129020 Example 139023 Example 148821 Example 158922 Example 168921 Example 178922 Example 189023 Example 197237 Comparative Example 14845 Comparative Example 25044 Comparative Example 35249 Comparative Example 45747 Comparative Example 55545 Comparative Example 65748 Comparative Example 75850 Comparative Example 86347 Comparative Example 96748 Comparative Example 105551

[0441]

[0442] Looking at Table 3 above, it can be seen that in the case of the secondary battery of the embodiment of the present invention, both the resistance increase rate (%) and the capacity retention rate (%) after high-temperature storage are improved compared to the lithium secondary battery of the comparative example.

[0443]

[0444] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the invention without departing from the spirit and technical scope of the invention as set forth in the claims below. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

Claims

1. Lithium salt; comprising a non-aqueous organic solvent and additives, The above additive is a non-aqueous electrolyte comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] (In the above chemical formula 1, R1 and R2 are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms).

2. In Paragraph 1, In the above chemical formula 1, R1 and R2 are each independently hydrogen or an alkyl group having 1 to 3 carbon atoms, a non-aqueous electrolyte.

3. In Paragraph 1, A non-aqueous electrolyte in which the compound represented by Chemical Formula 1 above is at least one selected from the group consisting of compounds represented by Chemical Formulas 1A to 1D below: [Chemical Formula 1A] [Chemical Formula 1B] [Chemical Formula 1C] [Chemical Formula 1D] .

4. In Paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte included in an amount of 0.01% to 13.0% by weight based on the total weight of the non-aqueous electrolyte.

5. In Paragraph 1, The compound represented by the above chemical formula 1 is a non-aqueous electrolyte included in an amount of 0.01% to 5.0% by weight based on the total weight of the non-aqueous electrolyte.

6. In Paragraph 1, The above additive is a non-aqueous electrolyte further comprising a lithium salt-based compound.

7. In Paragraph 6, The above lithium salt-based compound is a non-aqueous electrolyte selected from the group consisting of lithium bis-oxalatoborate (LiB(C2O4)2, LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorophosphate (LiPO2F2, LiDFP), and lithium difluoro(bis-oxalato)phosphate (LiDFOP).

8. In Paragraph 6, The above lithium salt-based compound is included in a non-aqueous electrolyte in an amount of 0.01% to 10.0% by weight based on the total weight of the non-aqueous electrolyte.

9. In Paragraph 1, The above-mentioned non-aqueous electrolyte further comprises at least one auxiliary additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, and silane compounds.

10. Anode; A cathode opposite to the anode above; 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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