Non-aqueous electrolyte and lithium secondary battery comprising same

Abstract

A non-aqueous electrolyte of the present invention comprises lithium salt, an organic solvent, and an additive, wherein the additive comprises a compound having a cyclic borate-based substituent and an oxazolidone-based precursor, and thus a lithium secondary battery using said electrolyte has improved cycle and storage characteristics at high temperatures and the overall performance is improved.

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 including the same.

[0002]

[0003] Recently, as the application areas of lithium secondary batteries have expanded across various technological fields, including not only power supply for electronic devices such as electrical, electronic, communication, and computers, but also power storage for large-area devices such as automobiles and power storage devices, the demand for high-capacity, high-output, and high-stability secondary batteries is increasing.

[0004] For example, as lithium secondary batteries are developed to have high capacity and high output, the probability of abnormal temperature rises due to various reasons during the charging and discharging process is increasing, which can lead to the so-called thermal runaway phenomenon in which sparks explode at high temperatures, and in case of thermal runaway, the fire is not easily extinguished, etc. Safety issues are recognized as one of the more important issues to be resolved in high capacity and high output lithium secondary batteries.

[0005]

[0006] The present invention aims to provide a non-aqueous electrolyte capable of suppressing the deterioration of a positive electrode, reducing side reactions between a positive electrode and an electrolyte, forming a uniform and dense SEI (Solid Electrolyte Interphase) film on a negative electrode, and improving the durability of a lithium secondary battery at high temperatures.

[0007] In addition, the present invention aims to provide a lithium secondary battery having improved high-temperature cycle characteristics and high-temperature storage characteristics by including the non-aqueous electrolyte, thereby improving overall performance.

[0008]

[0009] The present invention provides a non-aqueous electrolyte comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a compound represented by the following chemical formula 1:

[0010] [Chemical Formula 1]

[0011]

[0012]

[0013] In the above chemical formula 1, L1 is an arylene group having 6 to 20 carbon atoms that can be substituted with fluorine, L2 is selected from a direct bond or an alkylene group having 1 to 10 carbon atoms that can be substituted with fluorine, R1 and R2 are each independently any one selected from H, F, and an alkyl group having 1 to 5 carbon atoms that can be substituted with fluorine, and A1 is selected from the following chemical formula A-1 or chemical formula A-2.

[0014] [Chemical Formula A-1]

[0015]

[0016] [Chemical Formula A-2]

[0017]

[0018]

[0019] In the above chemical formula A-1 or chemical formula A-2, R 11 , R 12 , R 13 , R 14 , R 21 , R 22 , R 23 , R 24 , R 25 and R 26 are each independently selected from H, F, an alkyl group having 1 to 5 carbon atoms, and an alkyl group having 1 to 5 carbon atoms substituted with at least one fluorine, and * is a bonding site.

[0020]

[0021] In addition, the present invention provides a lithium secondary battery including a positive electrode; a negative electrode; and the non-aqueous electrolyte.

[0022]

[0023] The compound represented by Chemical Formula 1 provided as an additive for a non-aqueous electrolyte of the present invention has a structure in which film-forming reaction is possible at both terminals, so that a cross-linked film can be formed. Accordingly, a lithium secondary battery including the non-aqueous electrolyte of the present invention can form a uniform and dense SEI (Solid Electrolyte Interphase) film in a polymeric form on the negative electrode.

[0024] In addition, the compound of Chemical Formula 1 has a cyclic borate substituent and an oxazolidinedione matrix. The cyclic borate substituent forms a stable positive / negative electrode film through a ring-opening reaction, and the formed film has excellent lithium transport characteristics due to the presence of oxygen atoms surrounding the boron. In addition, the cyclic borate substituent reacts with an acid in the electrolyte to suppress metal dissolution from the positive electrode, thereby preventing damage to the film derived therefrom.

[0025] The oxazolidinedione skeleton has a large number of highly electronegative oxygen and nitrogen atoms within its structure, which allows for strong bonding with metals, thereby suppressing metal dissolution from the anode. Furthermore, oxazolidinedione forms a film through a ring-opening reaction, and the film thus formed contains a large number of electron-rich nitrogen (N) and oxygen (O) atoms, resulting in excellent lithium transport properties.

[0026] For example, when a non-aqueous electrolyte including the compound of the chemical formula 1 provided as an additive for a non-aqueous electrolyte of the present invention is applied to a lithium secondary battery, the passivation ability of SEI can be suppressed from deteriorating at high temperatures, thereby preventing deterioration of the negative electrode, thereby improving the life characteristics of the battery.

[0027] Therefore, by using the non-aqueous electrolyte of the present invention including the compound of the above chemical formula 1, a stable electrode-electrolyte interface can be formed even at high temperatures, and thus, high-temperature cycle characteristics and high-temperature storage characteristics can be improved, thereby realizing a lithium secondary battery with improved overall performance.

[0028]

[0029] The following drawings attached to this specification illustrate embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0030] Figure 1 shows the structure of a lithium secondary battery according to one embodiment of the present invention.

[0031] FIG. 2 is a drawing for explaining an automobile including a battery pack composed of the lithium secondary battery of FIG. 1.

[0032] In some of the accompanying drawings, corresponding components are designated by the same reference numerals. Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements. Furthermore, elements of known technology that are useful or essential in commercially feasible embodiments may often not be depicted so as not to obscure the spirit of various embodiments of the present invention.

[0033]

[0034] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0035] It should be understood that the terms “include,” “comprising,” or “having” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0036] In addition, in the description of "carbon atoms a to b" in the present specification, "a" and "b" mean 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" means an alkylene group including 1 to 5 carbon atoms, i.e., -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, -CH(CH3)CH2CH2-, -CH(CH2CH3)CH2CH2-, etc.

[0037] In addition, all alkyl groups in this specification may be substituted or unsubstituted. The term "substituted" as used herein, unless otherwise defined, means that at least one hydrogen bonded to carbon is replaced with an element other than hydrogen, for example, it means that it is replaced with a halogen atom, a nitro group, a nitrile group, etc.

[0038] When operating a secondary battery at a high voltage to increase its capacity, as charging and discharging progress, the film formed on the surface of the positive / negative electrode or the electrode surface structure deteriorates due to side reactions caused by deterioration of the electrolyte within the secondary battery, and for example, transition metal ions may be eluted from the positive electrode surface of the secondary battery. In this way, the eluted transition metal ions are electro-deposited on the negative electrode of the secondary battery, thereby lowering the passivation ability of the SEI, which causes the negative electrode to deteriorate.

[0039] This deterioration phenomenon of secondary batteries tends to accelerate when the potential of the positive electrode increases or when the battery is exposed to high temperatures.

[0040] In addition, when a lithium secondary battery is used continuously for a long time or is exposed to high temperatures, a so-called swelling phenomenon occurs in which gas is generated and the thickness of the battery increases. The amount of gas generated at this time is known to depend on, for example, the state of the SEI formed on the negative electrode.

[0041] In consideration of these points, the present invention supplies a non-aqueous electrolyte that suppresses the dissolution of metal ions from the positive electrode, forms a stable SEI film on the negative electrode, reduces the swelling phenomenon of the secondary battery, and increases stability at high temperatures.

[0042]

[0043] Hereinafter, the present invention will be described in more detail.

[0044] Referring to FIG. 1, a lithium secondary battery (100) according to one embodiment of the present invention includes an electrode assembly comprising a positive electrode (110), a negative electrode (120) facing the positive electrode (110), a separator (130) interposed between the positive electrode (110) and the negative electrode (120), and a battery case (150) that accommodates a non-aqueous electrolyte (140) and the electrode assembly and the non-aqueous electrolyte (140).

[0045] The above lithium secondary battery (100) can be manufactured by housing the electrode assembly in a battery case (150) and then injecting the above-described non-aqueous electrolyte (140).

[0046] A lithium secondary battery (100) according to one embodiment of the present invention may be manufactured in, for example, a prismatic type, a pouch type, a coin type, and a cylindrical type, depending on the manufacturing form.

[0047]

[0048] non-aqueous electrolyte

[0049] A non-aqueous electrolyte (140) according to one embodiment of the present invention includes a lithium salt, an organic solvent, and an additive, and includes a compound represented by the following chemical formula 1 as the additive. A lithium secondary battery (100) using a non-aqueous electrolyte (140) including the additive of the present invention can have excellent high-temperature cycle characteristics and high-temperature storage characteristics because deterioration due to interface reaction at high temperatures is suppressed.

[0050] [Chemical Formula 1]

[0051]

[0052]

[0053] The compound of the above chemical formula 1 can be decomposed and polymerized into a polymer form to form a uniform and dense polymeric film on the surface of the negative electrode, and the film thus formed can prevent or suppress precipitation and deposition due to transition metal dissolution from the positive electrode, thereby improving high-temperature durability and life characteristics. In addition, when a lithium secondary battery is exposed to a high potential, the compound of the above chemical formula 1 can form a film on the positive electrode with the remaining amount after forming the negative electrode film, thereby preventing or suppressing deterioration due to electrolyte oxidation and decomposition on the surface of the positive electrode.

[0054]

[0055] In the above chemical formula 1, L1 is an arylene group having 6 to 20 carbon atoms that can be substituted with fluorine. For example, L1 can be any one selected from the chemical formulas L1-1, L1-2, L1-3, and L1-4.

[0056] [Chemical formula L1-1]

[0057]

[0058]

[0059] [Chemical formula L1-2]

[0060]

[0061] [Chemical formula L1-3]

[0062]

[0063] [Chemical formula L1-4]

[0064]

[0065]

[0066] In the above chemical formulas L1-1, L1-2, L1-3 and L1-4, * represents a binding site.

[0067] In the above chemical formula 1, the L2 may be selected from an alkylene group having 1 to 10 carbon atoms that may be substituted with a direct bond or fluorine. In addition, the L2 may be selected from an alkylene group having 1 to 5 carbon atoms that may be substituted with a direct bond or fluorine. The L2 may be -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH3)CH-, -CH(CH3)CH2-, -CH(CH3)CH2CH2-, -CH(CH2CH3)CH2CH2-, etc.

[0068]

[0069] In the above chemical formula 1, A1 is selected from the following chemical formula A-1 or chemical formula A-2. In the case of the following chemical formula A-1, A1 is R on the BO side where the ring opening reaction occurs. 11 Inland R 14 There is an advantage in that the film formation reaction occurs more easily because there is less structural interference between the substituents.

[0070] [Chemical Formula A-1]

[0071]

[0072] [Chemical Formula A-2]

[0073]

[0074]

[0075] In the above chemical formula A-1 or chemical formula A-2, R 11 , R 12 , R 13 , R14 , R 21 , R 22 , R 23 , R 24 , R 25 and R 26 Each of which may be independently selected from H, F, an alkyl group having 1 to 5 carbon atoms, and an alkyl group having 1 to 5 carbon atoms substituted with one or more fluorines. In the above chemical formula A-1 or A-2, * is a bonding site. For example, in the above chemical formula A-1 or A-2, R 11 , R 12 , R 13 , R 14 , R 21 , R 22 , R 23 , R 24 , R 25 and R 26 may each be independently selected from H, F, an alkyl group having 1 to 3 carbon atoms, and an alkyl group having 1 to 3 carbon atoms substituted with at least one fluorine, or may each be independently selected from H, F, and a methyl group. In this case, the viscosity of the solvent does not increase, the ring opening reaction is not affected, and the structural stability of the compound may be better.

[0076]

[0077] According to one embodiment, the compound of formula 1 of the present invention may be any one selected from the following formulae 1a to 1j.

[0078] [Chemical Formula 1a]

[0079]

[0080] [Chemical Formula 1b]

[0081]

[0082] [Chemical Formula 1c]

[0083]

[0084] [Chemical Formula 1d]

[0085]

[0086] [Chemical Formula 1e]

[0087]

[0088] [Chemical formula 1f]

[0089]

[0090]

[0091] [Chemical formula 1g]

[0092]

[0093] [Chemical formula 1h]

[0094]

[0095] [Chemical Formula 1i]

[0096]

[0097] [Chemical formula 1j]

[0098]

[0099]

[0100] The additive for a non-aqueous electrolyte according to the present invention may be included in an amount of 0.01 to 10.0 parts by weight based on 100 parts by weight of a non-aqueous electrolyte, for example, 0.1 to 8.0 parts by weight, or 3.0 to 6.0 parts by weight. When the above range is satisfied, a sufficient amount of SEI can be formed, and the viscosity of the electrolyte is maintained at an appropriate level, so that the cycle characteristics or capacity characteristics of the lithium secondary battery (100) are excellent when stored at high temperatures.

[0101]

[0102] The lithium salt included in the non-aqueous electrolyte (140) of the present invention is used as an electrolyte salt in a lithium secondary battery (100) and is used as a medium for transferring ions. Typically, the lithium salt is, for example, Li as a cation. + , and the anion is F -, Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - At least one selected from may be cited.

[0103] For example, the lithium salts include LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10, LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2 (lithium bis(fluorosulfonyl)imide; LiFSI), LiN(SO2CF2CF3)2 (lithium bis(perfluoroethanesulfonyl)imide; LiBETI), and LiN(SO2CF3)2 (lithium bis(trifluoromethanesulfonyl)imide; LiTFSI). In addition to these, lithium salts commonly used in the electrolyte (140) of a lithium secondary battery (100) can be used without limitation.

[0104] The lithium salt may be appropriately changed within a generally usable range, but in order to obtain an optimal effect of forming a film for preventing corrosion of the electrode surface according to one embodiment, it may be included in the electrolyte at a concentration of 0.5 M to 3 M, or a concentration of 0.5 M to 2.5 M, or a concentration of 0.8 M to 2 M. When the concentration of the lithium salt satisfies the above range, the effect of improving the cycle characteristics during high-temperature storage of the lithium secondary battery (100) is sufficient, and the viscosity of the non-aqueous electrolyte (140) is appropriate, so that the electrolyte impregnation property can be improved.

[0105]

[0106] The organic solvent included in the non-aqueous electrolyte (140) of the present invention may include at least one organic solvent selected from a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

[0107] In one embodiment, the organic solvent may include a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, or a mixed organic solvent thereof.

[0108] The above cyclic carbonate-based organic solvent is a high-viscosity organic solvent with a high dielectric constant that can easily dissociate a lithium salt in an electrolyte, and may include at least one organic solvent selected from, for example, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and among these, may include ethylene carbonate.

[0109] The above linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and representative examples thereof include at least one organic solvent selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate, and may include, for example, ethylmethyl carbonate (EMC).

[0110] In addition, the organic solvent may further include at least one carbonate organic solvent selected from the cyclic carbonate organic solvent and the linear carbonate organic solvent, and at least one ester organic solvent selected from the linear ester organic solvent and the cyclic ester organic solvent, in order to produce an electrolyte having high ionic conductivity.

[0111] Such linear ester organic solvents may include, for example, at least one organic solvent selected from methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0112] In addition, the cyclic ester organic solvent may include at least one organic solvent selected from γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0113]

[0114] The above organic solvent may be used without limitation by adding organic solvents commonly used in non-aqueous electrolytes (140) as needed. For example, at least one organic solvent among an ether-based organic solvent, a glyme-based solvent, and a nitrile-based organic solvent may be additionally included.

[0115] As the above ether solvent, any one selected from dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL) or a mixture of two or more thereof may be used, but is not limited thereto.

[0116] The above 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, and may include at least one selected from dimethoxyethane (glyme, DME), diethoxyethane, diglyme, tri-glyme, and tetra-glyme (TEGDME), but is not limited thereto.

[0117] The above nitrile solvent may be at least one selected from acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited thereto.

[0118]

[0119] The non-aqueous electrolyte (140) of the present invention may additionally include a known electrolyte additive in the non-aqueous electrolyte (140) as needed to prevent or suppress the decomposition of the non-aqueous electrolyte (140) in a high-power environment, thereby causing cathode collapse, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and high-temperature battery expansion suppression effects.

[0120] These other electrolyte additives may include at least one SEI film forming additive selected from representative examples of cyclic carbonate compounds, sultone compounds, sulfate compounds, phosphate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds.

[0121] The above cyclic carbonate compounds may include vinylene carbonate (VC), vinylethylene carbonate, or fluoroethylene carbonate.

[0122] The above sultone compound may include at least one compound selected from 1,3-propane sultone (PS), 1,4-butane sultone, ethene sultone, 1,3-propene sultone (PRS), 1,4-butene sultone, and 1-methyl-1,3-propene sultone.

[0123] The above sulfate compounds may include ethylene sulfate (Esa), trimethylene sulfate (TMS), or methyl trimethylene sulfate (MTMS).

[0124] The above phosphate compound may include at least one selected compound selected from lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, tris(2,2,2-trifluoroethyl)phosphate, and tris(2,2,2-trifluoroethyl)phosphite.

[0125] The above borate compounds include tetraphenylborate, lithium oxalyldifluoroborate (LiODFB), and lithium bisoxalatoborate (LiB(C2O4)2, LiBOB).

[0126] The above nitrile compound may include at least one compound selected from succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0127] The benzene compound may include fluorobenzene, the amine compound may include triethanolamine or ethylenediamine, and the silane compound may include tetravinylsilane.

[0128] The above lithium salt compound is a compound different from the lithium salt included in the non-aqueous electrolyte, and may include lithium difluorophosphate (LiDFP), LiPO2F2, or LiBF4.

[0129] Among these other electrolyte additives, when a combination of vinylene carbonate (VC), 1,3-propane sultone (PS), and ethylene sulfate (Esa) is additionally included, a more robust SEI film can be formed on the surface of the negative electrode during the initial activation process of the secondary battery, and gas generation that may be generated due to decomposition of the electrolyte at high temperatures can be suppressed, thereby improving the high-temperature stability of the lithium secondary battery (100).

[0130]

[0131] The above-mentioned other electrolyte additives may be used in combination of two or more, and may be included in an amount of 0.1 wt% to 10 wt%, for example, 0.2 wt% to 8 wt%, or 0.5 wt% to 8 wt%, based on the total weight of the non-aqueous electrolyte (140). When the content of the above-mentioned other electrolyte additives satisfies the above range, the effect of improving ionic conductivity and cycle characteristics is more excellent.

[0132]

[0133] lithium secondary battery

[0134] The present invention also provides a lithium secondary battery (100) including the non-aqueous electrolyte (140).

[0135] The above lithium secondary battery (100) includes a positive electrode (110) including a positive electrode active material, a negative electrode (120) including a negative electrode active material, and the non-aqueous electrolyte (140) described above.

[0136] The above lithium secondary battery (100) may include a positive electrode (110) including a positive electrode active material, a negative electrode (120) including a negative electrode active material, a separator (130) interposed between the positive electrode and the negative electrode, and the non-aqueous electrolyte (140) described above.

[0137] The lithium secondary battery (100) of the present invention can be manufactured according to a conventional method known in the art. For example, an electrode assembly may be formed by sequentially stacking a positive electrode (110), a negative electrode (120), and a separator (130) between the positive electrode (110) and the negative electrode (120), and then inserting the electrode assembly into a battery case (150) and injecting a non-aqueous electrolyte (140) according to the present invention.

[0138]

[0139] (1) Bipolar

[0140] The above positive electrode (110) may include a positive electrode active material.

[0141] The positive electrode (110) may include a positive electrode current collector and a positive electrode active material layer positioned on at least one surface of the positive electrode current collector. The positive electrode active material layer may include the positive electrode active material. The positive electrode active material layer may further include at least one of a binder and a conductive material together with the positive electrode active material.

[0142] The above positive electrode (110) can be manufactured by coating a positive electrode mixture slurry containing a positive electrode active material, a binder, a conductive agent, and a solvent on a positive electrode current collector.

[0143] The above-mentioned positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used.

[0144]

[0145] The above-mentioned positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically may include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel or aluminum. For example, the lithium metal oxide may be a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (where Y is 0) <Y<1), LiMn 2-Z Ni Z O4 (where Z is 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2 (here, Y1 is 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2 (where Y2 is 0) <Y2<1), LiMn 2-Z1 Co Z1 O4 (where Z1 is 0<Z1<2), etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(where p is 0<p<1, q is 0<q<1, r is 0<r<1, and p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O4 (wherein, p1 is 0<p1<2, q1 is 0<q1<2, r1 is 0<r1<2, and p1+q1+r1=2), etc.), or lithium-nickel-cobalt-transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r2 M s2)O2 (wherein, M is selected from Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, where p2 is 0 < p2 < 1, q2 is 0 < q2 < 1, r2 is 0 < r2 < 1, s2 is 0 < s2 < 1, and p2 + q2 + r2 + s2 = 1), etc.), and any one or two or more compounds thereof may be included.

[0146] Among these, the lithium metal oxides are LiCoO2, LiMnO2, LiNiO2, lithium nickel-manganese-cobalt oxide (e.g., Li(Ni)) in that they can improve the capacity characteristics and stability of the battery. 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni) 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 and Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.), or lithium nickel manganese cobalt aluminum oxide (e.g. Li(Ni 0.86 Co 0.05 Mn 0.07 Al 0.02 )O2) etc., and any one of these or a mixture of two or more of them may be used.

[0147] Among these, a cathode active material having a nickel content of 80 atm% or more can be used because it can maximize the capacity characteristics of the battery. For example, the lithium transition metal oxide may include one represented by the following [Chemical Formula 2].

[0148] [Chemical Formula 2]

[0149] Li x Ni a Co b M 1 c M 2 d O2

[0150] In the above chemical formula 2, the M 1 is at least one selected from Mn and Al, and may be Mn or a combination of Mn and Al from the viewpoint of durability.

[0151] M 2 It may be at least one selected from Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P, and S.

[0152] The above x represents the atomic fraction of lithium in the lithium transition metal oxide, and x may be 0.90≤x≤1.1, or 0.95≤x≤1.08, or 1.0≤x≤1.08.

[0153] The above a represents the atomic fraction of nickel among the metal elements excluding lithium in the lithium transition metal oxide, and may be 0.80≤a<1.0, or 0.80≤a≤0.95, or 0.80≤a≤0.90. When the nickel content satisfies the above range, high-capacity characteristics can be realized.

[0154] The above b represents the atomic fraction of cobalt among the metal elements excluding lithium in the lithium transition metal oxide, 0 <b<0.2, 0<b≤0.15, 또는 0.01≤b≤0.10일 수 있다.

[0155] The above c is M among the metal elements excluding lithium in the lithium transition metal oxide. 1 It represents the atomic fraction of , 0 <c<0.2, 0<c≤0.15, 또는 0.01≤c≤0.10일 수 있다.

[0156] The above d is M among the metal elements excluding lithium in the lithium transition metal oxide. 2It represents the atomic fraction of , and can be 0≤d≤0.1, or 0≤d≤0.05.

[0157] The positive electrode active material may be included in an amount of 60 wt% to 99 wt%, for example, 70 wt% to 99 wt%, or 80 wt% to 98 wt%, based on the total weight of solids excluding the solvent in the positive electrode mixture slurry.

[0158]

[0159] The above binder is a component that assists in the bonding of the active material and the conductive material and the bonding to the current collector.

[0160] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluoroelastomer, and various copolymers.

[0161] Typically, the binder may be included in an amount of 1 wt% to 20 wt%, for example, 1 wt% to 15 wt%, or 1 wt% to 10 wt%, based on the total weight of the solid content excluding the solvent in the positive electrode slurry.

[0162] The conductive agent is a component for further improving the conductivity of the positive electrode active material, and may be added in an amount of 1 wt% to 20 wt% based on the total weight of the solid content in the positive electrode mixture slurry. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powders; conductive powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0163] Typically, the conductive agent may be included in an amount of 1 wt% to 20 wt%, or 1 wt% to 15 wt%, or 1 wt% to 10 wt%, based on the total weight of solids excluding the solvent in the positive electrode mixture slurry.

[0164] The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides an appropriate viscosity when including the positive electrode active material, and optionally a binder and a conductive material. For example, the positive electrode active material, and optionally a binder and a conductive material may be included so that the concentration of the solid content is 50 wt% to 95 wt%, for example, 70 wt% to 95 wt%, or 70 wt% to 90 wt%.

[0165]

[0166] (2) Cathode

[0167] The above negative electrode (120) may include a negative electrode active material.

[0168] The above negative electrode (120) may include a negative electrode current collector and a negative electrode active material layer positioned on at least one surface of the negative electrode current collector. The negative electrode active material layer may include the negative electrode active material. The negative electrode active material layer may further include at least one of a binder and a conductive material together with the negative electrode active material.

[0169] The above-mentioned negative electrode (120) can be manufactured, for example, by coating a negative electrode mixture slurry containing a negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, or a graphite electrode made of carbon (C) or the metal itself can be used as the negative electrode (120).

[0170] For example, when manufacturing a negative electrode (120) by coating a negative electrode mixture slurry on the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 ㎛ to 500 ㎛. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0171] In addition, the negative electrode active material may include at least one of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0172] As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used without particular limitation, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0173] As the above metal or an alloy of these metals with lithium, a metal selected from Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals with lithium can be used.

[0174] The above metal composite oxides include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1) and Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로부터 선택되는 것이 사용될 수 있다.

[0175] Materials capable of doping and dedoping the above lithium include Si, SiO x(0 <x≤2), 실리콘-탄소 복합체(Si-C composite), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로부터 선택되는 원소이며, Si은 아님), Sn, SnO2, Sn-Y(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로부터 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Y로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po 및 이들의 조합으로부터 선택될 수 있다.

[0176] Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

[0177]

[0178] According to one embodiment, the negative active material comprises graphite and SiO x (0≤x<2) may include at least one of the following. For example, the negative active material may include graphite and SiO x (0≤x<2) may be included. The negative active material may be graphite and SiO x When including (0≤x<2), the graphite and SiO x (0≤x<2) can be included in a weight ratio of 99:1 to 70:30 in terms of increasing the capacity of a lithium secondary battery.

[0179]

[0180] The above negative active material may be included in an amount of 60 wt% to 99 wt%, for example, 70 wt% to 99 wt%, or 80 wt% to 98 wt%, based on the total weight of the solid content in the negative electrode mixture slurry.

[0181] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0182] Typically, the binder may be included in an amount of 1 wt% to 20 wt%, for example, 1 wt% to 15 wt%, or 1 wt% to 10 wt%, based on the total weight of solids excluding the solvent in the negative electrode composite slurry.

[0183] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 1 wt% to 20 wt% based on the total weight of the solid content in the negative electrode mixture slurry. The conductive agent is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and examples thereof include carbon powders such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powders such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon powders; conductive powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0184] The above-mentioned conductive agent may be included in an amount of 1 wt% to 20 wt%, for example, 1 wt% to 15 wt%, or 1 wt% to 10 wt%, based on the total weight of solids excluding the solvent in the negative electrode mixture slurry.

[0185] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides an appropriate viscosity when including the negative electrode active material, and optionally a binder and a conductive material. For example, the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material may be 50 wt% to 95 wt%, for example, 70 wt% to 90 wt%.

[0186] When using the metal itself as the above-mentioned cathode (120), it can be manufactured by physically bonding, rolling, or depositing the metal onto the metal thin film itself or the cathode current collector. The deposition method can use an electrical deposition method or a chemical vapor deposition method.

[0187] For example, the metal to be bonded / rolled / deposited on the metal thin film itself or the negative electrode current collector may include one metal selected from lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In), or an alloy of two metals.

[0188]

[0189] (3) Membrane

[0190] As the separator (130), a conventional porous polymer film conventionally used as a separator, for example, a porous polymer film made of a polyolefin polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, may be used alone or in a laminated manner, or a conventional porous nonwoven fabric, for example, 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 secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0191]

[0192] There is no particular limitation on the external shape of the lithium secondary battery (100) of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0193]

[0194] Hereinafter, the present invention will be described through examples. However, the following examples are merely illustrative and serve to aid understanding of the present invention and do not limit its scope. It will be apparent to those skilled in the art that various modifications and variations are possible within the scope and technical spirit of this disclosure, and such modifications and variations are naturally within the scope of the appended claims.

[0195]

[0196] Example

[0197] Example 1

[0198] (Manufacture of non-aqueous electrolyte)

[0199] A non-aqueous solvent was prepared by dissolving LiPF6 in an organic solvent (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 20:80 volume ratio) to a concentration of 1.2 M, and 0.05 g of a compound of the following chemical formula 1a was added to 99.95 g of the non-aqueous solvent to prepare a non-aqueous electrolyte.

[0200] [Chemical Formula 1a]

[0201]

[0202]

[0203] (Lithium secondary battery manufacturing)

[0204] Cathode active material (LiNi) 0.90 Co 0.03 Mn 0.06 Al 0.01 O2), a conductive agent (carbon black), and a binder (polyvinylidene fluoride) were added to a solvent, N-methyl-2-pyrrolidone (NMP), in a weight ratio of 97.5:1.3:1.2 to prepare a positive electrode slurry (solid content 74 wt%). The positive electrode slurry was applied to one surface of a positive electrode current collector (Al thin film) having a thickness of 130 μm, and dried and roll pressed to prepare a positive electrode.

[0205] A negative electrode slurry (solid content 60 wt%) was prepared by adding a negative electrode active material (graphite: SiO = 97:3 weight ratio), a conductive agent (carbon black), and a binder (polyvinylidene fluoride) to a solvent, N-methyl-2-pyrrolidone (NMP), in a weight ratio of 96.8:0.2:3.0. The negative electrode slurry was applied to one surface of a 128 ㎛ thick negative electrode current collector (Cu thin film), and drying and roll pressing were performed to prepare a negative electrode.

[0206] A porous polymer separator made of a polyolefin polymer was interposed between the positive and negative electrodes manufactured above in a dry room, and then the non-aqueous electrolyte manufactured above was injected to manufacture a secondary battery.

[0207]

[0208] Example 2

[0209] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of the compound of the following chemical formula 1a was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0210]

[0211] Example 3

[0212] A secondary battery was manufactured in the same manner as in Example 1, except that 10 g of a compound of the following chemical formula 1a was added to 90 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0213]

[0214] Example 4

[0215] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of the compound of the following chemical formula 1b was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0216] [Chemical Formula 1b]

[0217]

[0218]

[0219] Example 5

[0220] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of the compound of the following chemical formula 1c was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0221] [Chemical Formula 1c]

[0222]

[0223]

[0224]

[0225] Example 6

[0226] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of a compound of the following chemical formula 1d was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0227] [Chemical Formula 1d]

[0228]

[0229]

[0230] Example 7

[0231] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of a compound of the following chemical formula 1e was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0232] [Chemical Formula 1e]

[0233]

[0234]

[0235] Example 8

[0236] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of a compound of the following chemical formula 1f was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0237] [Chemical formula 1f]

[0238]

[0239] Example 9

[0240] A secondary battery was manufactured in the same manner as in Example 1, except that 5 g of a compound of the following chemical formula 1 g was added to 95 g of the non-aqueous solvent manufactured in Example 1 to manufacture a non-aqueous electrolyte.

[0241] [Chemical formula 1g]

[0242]

[0243]

[0244] Comparative Example 1

[0245] A secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was manufactured using 100 g of the non-aqueous solvent manufactured in Example 1. For example, in Comparative Example 1, a secondary battery was manufactured without using the non-aqueous electrolyte additive according to the present invention.

[0246]

[0247] Experimental Example 1 - Evaluation of High-Temperature Cycle Characteristics

[0248] For each of the secondary batteries manufactured in Examples 1 to 9 and Comparative Example 1, cycle characteristics were evaluated.

[0249] Each of the batteries manufactured in Examples 1 to 9 and Comparative Example 1 was charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 45°C, and then discharged to 2.5 V under CC, 0.33 C conditions, which was considered one cycle, and then 300 cycles of charge and discharge were performed. The capacity retention rate after 300 cycles was measured compared to the initial capacity after 1 cycle.

[0250] Capacity retention rate (%) = {(discharge capacity after 300 cycles / discharge capacity after 1 cycle)} × 100

[0251] In addition, the resistance increase rate after 12 weeks of storage compared to the initial resistance was measured. Meanwhile, before storage, the SOC of the secondary battery was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse application. After 12 weeks, the resistance of the stored secondary battery was measured using the same method, and the increased resistance during the 12-week storage period was calculated. The resistance increase rate after 12 weeks was derived by calculating the percentage ratio of the increased resistance with respect to the initial capacity of the secondary battery.

[0252] In addition, the resistance increase rate after 300 cycles compared to the initial resistance was measured. Specifically, the discharge capacity after 1 cycle was measured using an electrochemical charger / discharger, the SOC was adjusted to 50% SOC, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse application. After 300 cycles of charge / discharge, the resistance of the secondary battery was measured using the same method, and the increased resistance during 300 cycles was calculated. The percentage ratio of the increased resistance to the initial capacity of the secondary battery was calculated to derive the resistance increase rate after 12 weeks.

[0253] Resistance increase rate (%) = (Resistance after 300 cycles - Initial resistance) / (Initial resistance) × 100

[0254] The results are shown in Table 1 below.

[0255]

[0256] Capacity retention rate (%) Resistance increase rate (%) Example 18815 Example 29013 Example 38914 Example 48914 Example 58816 Example 69014 Example 79014 Example 88915 Example 98913 Comparative example 15653

[0257] As shown in Table 1, the capacity retention rates of the secondary batteries of Examples 1 to 9 were 88% to 90%, which is significantly superior to 56% of Comparative Example 1. In addition, the resistance increase rates of the secondary batteries of Examples 1 to 9 were 13% to 16%, which is significantly superior to 53% of Comparative Example 1. As a result, the secondary batteries of Examples 1 to 9 containing about 0.1 wt% to 10 wt% of the electrolyte additive had superior high-temperature cycle characteristics in terms of capacity retention rate and resistance increase rate compared to the secondary battery of Comparative Example 1 not containing the electrolyte additive.

[0258] Experimental Example 2 - Evaluation of High-Temperature Storage Characteristics

[0259] For each of the secondary batteries manufactured in Examples 1 to 9 and Comparative Example 1, high-temperature storage characteristics were evaluated.

[0260] For example, the secondary batteries of Examples 1 to 9 and Comparative Example 1 were charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C, respectively, and discharged to 2.5 V under CC, 0.33 C conditions to perform initial charging and discharging. Afterwards, they were fully charged to 4.4 V, 0.05 C under CC / CV, 0.33 C conditions at 25°C, and then stored at 60°C for 12 weeks.

[0261] Before storage, the capacity of a fully charged secondary battery was measured and set to the initial capacity of the secondary battery. After 12 weeks, the capacity of the stored secondary battery was measured and the capacity loss during the 12-week storage period was calculated. The percentage ratio of the decreased capacity to the initial capacity of the secondary battery was calculated to derive the capacity retention rate after 12 weeks.

[0262] Capacity retention rate (%) = (Discharge capacity after 12 weeks of storage / Initial discharge capacity) × 100

[0263] In addition, the resistance increase rate after 12 weeks of storage compared to the initial resistance was measured. Specifically, before storage, the SOC of the secondary battery was adjusted to 50%, and then a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated through the difference between the voltage before and after the pulse application. After 12 weeks, the resistance of the stored secondary battery was measured using the same method, and the increased resistance during the 12-week storage period was calculated. The resistance increase rate after 12 weeks was derived by calculating the percentage ratio of the increased resistance with respect to the initial capacity of the secondary battery.

[0264] Resistance increase rate (%) = (Resistance after 12 weeks - Initial resistance) / (Initial resistance) × 100

[0265] The results are shown in Table 2 below.

[0266]

[0267] Capacity retention rate (%) Resistance increase rate (%) Example 19212 Example 29311 Example 39113 Example 49212 Example 59013 Example 69212 Example 79011 Example 89113 Example 99212 Comparative Example 16154

[0268] As shown in Table 2 above, the capacity retention rates of the secondary batteries of Examples 1 to 9 were 90% to 93%, which was significantly superior to 61% of Comparative Example 1. In addition, the resistance increase rates of the secondary batteries of Examples 1 to 9 were 11% to 13%, which was significantly superior to 54% of Comparative Example 1. As a result, it was confirmed that the secondary batteries of Examples 1 to 9 containing 0.1 wt% to 10 wt% of the electrolyte additive had stable performance in terms of capacity retention rate and resistance increase rate at high temperatures compared to the secondary battery of Comparative Example 1 not containing the electrolyte additive.

[0269] Experimental Example 3 - Thermal Stability Evaluation

[0270] For each of the secondary batteries manufactured in Examples 1 to 9 and Comparative Example 1, thermal stability was evaluated.

[0271] For example, the lithium secondary batteries manufactured in the above examples and comparative examples were subjected to an activation (formation) process, and then charged (0.05C cut off) under constant current / constant voltage conditions at a 0.33C rate at 25°C to 4.4 V to fully charge to 100% SOC. The fully charged batteries were heated to 140°C at a 5°C / min heating rate, and then left for 1 hour to conduct a hot box evaluation experiment to check for ignition. If no ignition occurred, it was evaluated as Pass, and if ignition occurred, it was evaluated as Fail. The results are shown in Table 3 below.

[0272]

[0273] Hotbox Test ResultsExample 1PassExample 2PassExample 3PassExample 4PassExample 5PassExample 6PassExample 7PassExample 8PassExample 9PassComparative Example 1Fail

[0274] As shown in Table 3 above, it was confirmed that the secondary batteries of Examples 1 to 9 had superior thermal stability compared to the secondary battery of Comparative Example 1 as a result of the hot box test. FIG. 2 is a drawing for explaining an automobile (300) including a battery pack (200) composed of the lithium secondary battery (100) of FIG. 1.

[0275] Referring to FIG. 2, a vehicle (300) according to one embodiment of the present invention may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle, and includes a battery pack (200) composed of a lithium secondary battery (100) according to one embodiment of the present invention. The vehicle (300) includes a four-wheeled vehicle and a two-wheeled vehicle. The vehicle (300) operates by receiving power from the battery pack (200) according to one embodiment of the present invention.

[0276] Although the present disclosure has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the various embodiments of the present disclosure may be made without departing from the technical scope of the various embodiments of the present disclosure as set forth in the claims below. Accordingly, the technical scope of the various embodiments of the present disclosure should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0277]

[0278] <Explanation of symbols>

[0279] 100: Lithium secondary battery

[0280] 110: Positive

[0281] 120: Cathode

[0282] 130: Membrane

[0283] 140: Non-aqueous electrolyte

[0284] 150: Battery case

[0285] 200: Battery Pack

[0286] 300: Car

Claims

1. Contains lithium salt, organic solvent and additives, The above additive is a non-aqueous electrolyte containing a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, The above L1 is an arylene group having 6 to 20 carbon atoms that can be substituted with fluorine, The above L2 is selected from alkylene groups having 1 to 10 carbon atoms that can be substituted with a direct bond or fluorine, The above R1 and R2 are each independently selected from H, F, and an alkyl group having 1 to 5 carbon atoms that can be substituted with fluorine, The above A1 is selected from the following chemical formula A-1 or chemical formula A-2, [Chemical Formula A-1] [Chemical Formula A-2] In the above chemical formula A-1 or chemical formula A-2, R 11 , R 12 , R 13 , R 14 , R 21 , R 22 , R 23 , R 24 , R 25 and R 26 are each independently selected from H, F, an alkyl group having 1 to 5 carbon atoms, and an alkyl group having 1 to 5 carbon atoms substituted with at least one fluorine, * is the binding site.

2. In claim 1, The above L1 is a non-aqueous electrolyte selected from the chemical formulas L1-1, L1-2, L1-3 and L1-4. [Chemical formula L1-1] [Chemical formula L1-2] [Chemical formula L1-3] [Chemical formula L1-4] In the above chemical formulas L1-1, L1-2, L1-3 and L1-4, * represents a binding site.

3. In claim 1, The above L2 is a non-aqueous electrolyte with direct bonding.

4. In claim 1, A non-aqueous electrolyte wherein R1 and R2 are each independently H, F or CH3.

5. In claim 1, The above A1 is a non-aqueous electrolyte having the following chemical formula A-1. [Chemical Formula A-1] 6. In claim 1, The compound of the above chemical formula 1 is a non-aqueous electrolyte selected from any one of the following chemical formulas 1a to 1j. [Chemical Formula 1a] [Chemical Formula 1b] [Chemical Formula 1c] [Chemical Formula 1d] [Chemical Formula 1e] [Chemical formula 1f] [Chemical formula 1g] [Chemical formula 1h] [Chemical Formula 1i] [Chemical formula 1j] .

7. In claim 1, A non-aqueous electrolyte in which the compound represented by the above chemical formula 1 is included in an amount of 0.01 to 10.0 parts by weight per 100 parts by weight of the non-aqueous electrolyte.

8. In claim 1, The above lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10 , LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiN(SO2F)2, LiN(SO2CF2CF3)2, and LiN(SO2CF3)2.

9. In claim 1, A non-aqueous electrolyte comprising the lithium salt in a concentration of 0.5 M to 3 M.

10. In claim 1, A non-aqueous electrolyte comprising at least one organic solvent selected from a cyclic carbonate-based organic solvent, a linear carbonate-based organic solvent, a linear ester-based organic solvent, and a cyclic ester-based organic solvent.

11. Bipolar; cathode; and A lithium secondary battery comprising a non-aqueous electrolyte according to claim 1.

12. In claim 11, The above positive electrode includes a positive electrode active material, A lithium secondary battery wherein the positive electrode active material includes a lithium nickel-cobalt-manganese oxide.

13. In claim 11, The above negative electrode includes a negative electrode active material, The above negative active material is graphite and SiO x A lithium secondary battery comprising at least one of (0≤x<2).

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