Novle additives for nonaqueous electrolyte and lithium secondary battery containing the same

Abstract

The present invention relates to a novel additive for a non-aqueous electrolyte and a lithium secondary battery containing the same. The additive for a non-aqueous electrolyte includes an ionic compound represented by Chemical Formula 1, thereby forming a film on the electrode surface during activation of the secondary battery, which prevents the generation of a large amount of gas under high temperature conditions. Additionally, since metal ions can be leached from the electrode, preventing a decrease in the cell's OCV and a reduction in capacity retention rate, the durability, performance, and high-temperature safety of the battery can be effectively improved.

Description

Technology Field

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

[0003] Recently, secondary batteries are being widely applied not only to small devices such as portable electronic devices, but also to medium and large devices such as battery packs or power storage devices for hybrid or electric vehicles. Examples of such secondary batteries include lithium-ion batteries, lithium batteries, lithium-ion capacitors, and non-aqueous electrolyte batteries such as sodium-ion batteries.

[0004] Among these non-aqueous electrolyte batteries, lithium-ion batteries are used by injecting an electrolyte into a battery cell comprising a positive electrode containing a positive electrode active material capable of intercalating and deintercalating lithium, and a negative electrode containing a negative electrode active material capable of intercalating and deintercalating lithium. In particular, the electrolyte uses an organic solvent in which a lithium salt is dissolved, and it is important in determining the stability and performance of the lithium secondary battery.

[0005] For example, LiPF6, which is generally the most widely used lithium salt in electrolytes, reacts with the electrolyte solvent to accelerate solvent depletion and generate HF. This generated HF not only produces a large amount of gas under high temperature conditions but can also leach out metal ions. If the leached metal ions are deposited on the surface of the negative electrode, it causes an increase in negative electrode potential and a decrease in cell OCV, thereby degrading the battery's performance, lifespan, and high-temperature safety. The problem to be solved

[0007] Accordingly, the objective of the present invention is to provide a technology that prevents direct contact between the anode and the electrolyte by forming a film on the electrode surface, and suppresses gas generation by reducing the oxidative decomposition of the electrolyte while preventing direct contact between the anode and HF, PF5, etc., and improves the capacity retention rate by improving the metal ion precipitation phenomenon from the anode, while preventing a drop in the OCV of the battery. means of solving the problem

[0009] In order to solve the aforementioned problem,

[0010] In one embodiment of the present invention,

[0011] The present invention provides an electrolyte additive for a secondary battery comprising a compound represented by the following chemical formula 1:

[0012] [Chemical Formula 1]

[0013]

[0014] In the above chemical formula 1,

[0015] R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0016] R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and

[0017] R3 is a fluoro group, a C1- to C10 alkyl group, a C1- to C10 alkoxy group, or However,

[0018] The above alkyl group, alkoxy group and One or more of the hydrogen atoms contained in can be replaced with fluorine atoms, and

[0019] X is an oxygen atom (O) or -NR4, and R4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0020] M comprises one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, and

[0021] l is an integer from 1 to 6, and

[0022] m is an integer from 2 to 20.

[0024] Specifically, the above R1 is hydrogen or a methyl group, and

[0025] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0026] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0027] X is an oxygen atom (O), -NH or -NCH3, and

[0028] M is lithium, and

[0029] l is an integer of 1 or 2, and

[0030] m can be an integer from 2 to 10.

[0032] More specifically, the compound represented by the above chemical formula 1 may be one or more of the following <Structural Formula 1> to <Structural Formula 48>:

[0033]

[0035] In addition, in one embodiment of the present invention,

[0036] The present invention provides an electrolyte composition for a lithium secondary battery comprising a non-aqueous organic solvent; a lithium salt; and a compound represented by the following chemical formula 1:

[0037] [Chemical Formula 1]

[0038]

[0039] In the above chemical formula 1,

[0040] R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0041] R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and

[0042] R3 is a fluoro group, a C1- to C10 alkyl group, a C1- to C10 alkoxy group, or However,

[0043] The above alkyl group, alkoxy group and One or more of the hydrogen atoms contained in can be replaced with fluorine atoms, and

[0044] X is an oxygen atom (O) or -NR4, and R4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0045] M comprises one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, and

[0046] l is an integer from 1 to 6, and

[0047] m is an integer from 2 to 20.

[0049] At this time, the compound represented by the above chemical formula 1 may be included in an amount of 0.01 to 3 weight% with respect to the total weight of the electrolyte composition.

[0050] In addition, the lithium salts are LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB10Cl 10 It may include one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi and (FSO2)2NLi.

[0051] In addition, the above-mentioned non-aqueous organic solvent may include N-methyl-2-pyrrolidinone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfranc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, and ethyl propionate.

[0053] Furthermore, in one embodiment of the present invention,

[0054] An electrode assembly comprising: a positive electrode comprising one or more positive active materials among lithium metal oxides represented by the following chemical formulas 2 and 3; a negative electrode; and a separator interposed between the positive electrode and the negative electrode, and

[0055] A lithium secondary battery comprising an electrolyte composition according to the present invention is provided:

[0056] [Chemical Formula 2]

[0057] Li x [Ni y Co z Mn w M 1 v ]O2

[0058] [Chemical Formula 3]

[0059] LiM 2 p Mn (2-p) O4

[0060] In the above chemical formulas 2 and 3,

[0061] M 1It is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and

[0062] x, y, z, w, and v are 1.0≤x≤1.30, 0.5≤y<1, 0, respectively. <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고,

[0063] M 2 is Ni, Co, or Fe, and

[0064] p is 0.05≤p≤0.6.

[0065] At this time, the cathode active material may include one or more selected from the group consisting of LiNi0.8Co0.1Mn0.1O2, LiNi0.6Co0.2Mn0.2O2, LiNi0.9Co0.05Mn0.05O2, LiNi0.6Co0.2Mn0.1Al0.1O2, LiNi0.6Co0.2Mn0.15Al0.05O2, LiNi0.7Co0.1Mn0.1Al0.1O2, and LiNi0.5Mn1.5O4.

[0066] In addition, the above-mentioned cathode active material is composed of a carbon material and a silicon material, and the silicon material may include one or more of silicon (Si), silicon carbide (SiC) and silicon oxide (SiOq, provided that 0.8≤q≤2.5).

[0067] In addition, the silicon material may be included in an amount of 1 to 20 weight percent based on the total weight of the negative electrode active material. Effects of the invention

[0069] The electrolyte additive according to the present invention can prevent the generation of a large amount of gas under high temperature conditions by forming a film on the electrode surface when activating a secondary battery, and can effectively prevent the leaching of metal ions from the electrode, thereby preventing a decrease in the cell's OCV and a reduction in capacity retention rate, thus effectively improving the durability, performance, and high-temperature safety of the battery. Specific details for implementing the invention

[0071] The present invention is capable of various modifications and may have various embodiments, and specific embodiments are to be described in detail in the detailed description.

[0072] However, this is not intended to limit the invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0073] In the present invention, terms such as "comprising" or "having" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0074] Furthermore, in the present invention, when a part such as a layer, film, region, or plate is described as being "on" another part, this includes not only cases where it is "immediately above" the other part, but also cases where there is another part in between. Conversely, when a part such as a layer, film, region, or plate is described as being "under" another part, this includes not only cases where it is "immediately below" the other part, but also cases where there is another part in between. Additionally, in the present application, being "placed on" may include cases where it is placed on the lower part as well as on the upper part.

[0075] In addition, in the present invention, "include as a main component" may mean including a defined component in an amount of 50% or more by weight, 60% or more by weight, 70% or more by weight, 80% or more by weight, 90% or more by weight, or 95% or more by weight with respect to the total weight. For example, "include graphite as a main component as a negative electrode active material" may mean including graphite in an amount of 50% or more by weight, 60% or more by weight, 70% or more by weight, 80% or more by weight, 90% or more by weight, or 95% or more by weight with respect to the total weight of the negative electrode active material, and in some cases, it may mean that the entire negative electrode active material is made of graphite and includes graphite in an amount of 100% by weight.

[0077] The present invention will be described in more detail below.

[0079] Electrolyte additives for secondary batteries

[0080] In one embodiment of the present invention,

[0081] The present invention provides an electrolyte additive for a secondary battery comprising a compound represented by the following chemical formula 1:

[0082] [Chemical Formula 1]

[0083]

[0084] In the above chemical formula 1,

[0085] R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0086] R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and

[0087] R3 is a fluoro group, a C1- to C10 alkyl group, a C1- to C10 alkoxy group, or However,

[0088] The above alkyl group, alkoxy group and One or more of the hydrogen atoms contained in can be replaced with fluorine atoms, and

[0089] X is an oxygen atom (O) or -NR4, and R4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0090] M comprises one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, and

[0091] l is an integer from 1 to 6, and

[0092] m is an integer from 2 to 20.

[0094] The electrolyte additive for a secondary battery according to the present invention comprises an ionic compound having a core formed by combining a (meth)acrylate group or a (meth)acrylamide group on one side, centered around a sulfonylimide group as in Formula 1, through a cyclic unsaturated hydrocarbon group having a conjugated structure or a cyclic unsaturated heterohydrocarbon group having a structure in which a heteroatom is introduced to the cyclic unsaturated hydrocarbon group. The above compound includes a cyclic unsaturated hydrocarbon group having a conjugated structure or a functional group having a structure in which a heteroatom is introduced to the cyclic unsaturated hydrocarbon group as a linker between the sulfonylimide group and the (meth)acrylate group or the (meth)acrylamide group, thereby enabling the implementation of a conjugated structure from the sulfonylimide group to the (meth)acrylate group or the (meth)acrylamide group, so that it can more stably contain charge within the molecule. Accordingly, a secondary battery containing the above compound can stably and uniformly form an organic and / or inorganic film on the surface of the positive electrode and / or negative electrode upon activation, thereby suppressing the decomposition of the electrolyte and the generation of gas when the battery is exposed to high temperatures, while improving the phenomenon of the battery's OCV drop and capacity retention rate reduction occurring at the positive electrode.

[0096] To this end, in the compound represented by the above chemical formula 1,

[0097] R1 is hydrogen, a methyl group, an ethyl group, or a propyl group, and

[0098] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0099] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0100] X is an oxygen atom (O), -NH, -NCH3 or -NCH2CH3, and

[0101] M comprises one or more selected from the group consisting of lithium, sodium, tetramethylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer from 1 to 6, and m is an integer from 2 to 20.

[0103] Specifically, R1 is hydrogen or a methyl group, and

[0104] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0105] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0106] X is an oxygen atom (O), -NH or -NCH3, and

[0107] M is lithium, l is an integer of 1 or 2, and m can be an integer from 2 to 10.

[0109] As an example, the compound represented by the above chemical formula 1 may be one or more of the following <Structural Formula 1> to <Structural Formula 48>:

[0110]

[0112] As described above, the electrolyte additive according to the present invention has a (meth)acrylate group or a (meth)acrylamide group bonded to one side of a sulfonylimide group through a functional group having a conjugated structure or a structure in which a heteroatom is introduced to the sulfonylimide group, and by having a structure having an internal charge within the molecule, it can directly participate in the solvation shell of lithium ions even at a low potential during battery activation, thereby uniformly forming a negatively charged and / or inorganic film through a reduction reaction on the negative electrode surface, and simultaneously uniformly forming an inorganic film through an oxidation reaction on the positive electrode surface.

[0113] Through this, the electrolyte additive can suppress the decomposition of the electrolyte and the generation of gas when the battery is exposed to high temperatures, while improving the reduction in OCV and capacity of the battery occurring at the positive electrode, thereby preventing the degradation of the secondary battery and further improving high-temperature safety.

[0115] Electrolyte composition for lithium secondary batteries

[0116] In addition, in one embodiment of the present invention,

[0117] The present invention provides an electrolyte composition for a lithium secondary battery comprising a non-aqueous organic solvent; a lithium salt; and a compound represented by the following chemical formula 1:

[0118] [Chemical Formula 1]

[0119]

[0120] In the above chemical formula 1,

[0121] R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0122] R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and

[0123] R3 is a fluoro group, a C1- to C10 alkyl group, a C1- to C10 alkoxy group, or However,

[0124] The above alkyl group, alkoxy group and One or more of the hydrogen atoms contained in can be replaced with fluorine atoms, and

[0125] X is an oxygen atom (O) or -NR4, and R4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0126] M comprises one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, and

[0127] l is an integer from 1 to 6, and

[0128] m is an integer from 2 to 20.

[0130] The electrolyte composition for a lithium secondary battery according to the present invention is a non-aqueous electrolyte composition and has a composition comprising a lithium salt and an electrolyte additive in a non-aqueous organic solvent. Here, the electrolyte composition includes the electrolyte additive of the present invention described above, which includes a compound represented by Chemical Formula 1 as the electrolyte additive, and when the battery containing the same is activated, it directly participates in the solvation shell of lithium ions to uniformly form a negatively charged and / or inorganic film through a reduction reaction on the surface of the negative electrode.

[0131] To this end, in the compound represented by the above chemical formula 1,

[0132] R1 is hydrogen, a methyl group, an ethyl group, or a propyl group, and

[0133] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0134] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0135] X is an oxygen atom (O), -NH, -NCH3 or -NCH2CH3, and

[0136] M comprises one or more selected from the group consisting of lithium, sodium, tetramethylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer from 1 to 6, and m is an integer from 2 to 20.

[0138] Specifically, R1 is hydrogen or a methyl group, and

[0139] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0140] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0141] X is an oxygen atom (O), -NH or -NCH3, and

[0142] M is lithium, l is an integer of 1 or 2, and m can be an integer from 2 to 10.

[0144] In addition, the compound represented by Chemical Formula 1 may be included in the electrolyte composition in a specific amount. Specifically, the compound represented by Chemical Formula 1 may be included in an amount of 0.01 to 5 weight% with respect to the total weight of the electrolyte composition, and more specifically, in an amount of 0.05 to 3 weight% or 1.0 to 2.5 weight% with respect to the total weight of the electrolyte composition. The present invention can prevent the decrease in wettability to the electrode and separator by increasing the viscosity of the electrolyte composition using an excess amount of electrolyte additive whose content falls outside the range described above, and simultaneously prevent the reduction in the ion conductivity of the electrolyte composition from causing a decrease in battery performance. Furthermore, the present invention can prevent the effect of the additive from being negligible by using a trace amount of electrolyte additive that falls outside the range described above.

[0146] Meanwhile, the lithium salt used in the above electrolyte composition may be applied without particular limitation as long as it is used in the industry for non-aqueous electrolytes. Specifically, the lithium salt is LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl 10 It may include one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi and (FSO2)2NLi.

[0147] There are no specific restrictions on the concentration of these lithium salts, but the lower limit of the appropriate concentration range is 0.5 mol / L or higher, specifically 0.7 mol / L or higher, more specifically 0.9 mol / L or higher, and the upper limit is 2.5 mol / L or lower, specifically 2.0 mol / L or lower, more specifically 1.5 mol / L or lower. If the concentration of the lithium salt is lower than 0.5 mol / L, the ion conductivity decreases, which may lead to a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery. In addition, if the concentration of the lithium salt exceeds 2.5 mol / L, the viscosity of the electrolyte for the non-aqueous electrolyte battery increases, which may also lead to a decrease in ion conductivity and a decrease in the cycle characteristics and output characteristics of the non-aqueous electrolyte battery.

[0148] In addition, when a large amount of lithium salt is dissolved in a non-aqueous organic solvent at once, the liquid temperature may rise due to the heat of dissolution of the lithium salt. If the temperature of the non-aqueous organic solvent rises significantly due to the heat of dissolution of the lithium salt in this way, in the case of a lithium salt containing fluorine, decomposition is accelerated and there is a risk of hydrogen fluoride (HF) being generated. Hydrogen fluoride (HF) is undesirable because it causes degradation of battery performance. Therefore, the temperature at which the lithium salt is dissolved in the non-aqueous organic solvent is not particularly limited, but can be controlled to -20 to 80°C, and specifically to 0 to 60°C.

[0149] In addition, the non-aqueous organic solvent used in the above electrolyte composition can be applied without particular limitation as long as it is used in the industry for non-aqueous electrolytes. Specifically, the above-mentioned non-aqueous organic solvents include, for example, N-methyl-2-pyrrolidinone, ethylene carbonate (EC), propylene carbonate, butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), gamma-butyrolactone, 1,2-dimethoxyethane (DME), tetrahydroxyfranc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxymethane, dioxolone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl propionate, ethyl propionate, etc. Aprotic organic solvents can be used.

[0150] In addition, the non-aqueous organic solvent used in the present invention may be used as a single type, or two or more types may be mixed in any combination or ratio according to the application. Among these, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, diethyl carbonate, dimethyl carbonate, and ethylmethyl carbonate are particularly preferred in terms of electrochemical stability against oxidation and reduction and chemical stability against reaction with heat or solutes.

[0151] Meanwhile, the above electrolyte composition may further include additives in addition to the basic components described above. As long as it does not impair the essence of the present invention, additives generally used in the non-aqueous electrolyte of the present invention may be added in any proportion. Specifically, examples include compounds having an overcharge prevention effect, a negative electrode film formation effect, and a positive electrode protection effect, such as cyclohexylbenzene, biphenyl, t-butylbenzene, carbonate, vinylethylene carbonate, difluoroanisole, fluoroethylene carbonate, propanesulfone, succinonitrile, and dimethylvinylene carbonate. In addition, it is also possible to use the electrolyte for a non-aqueous electrolyte battery by pseudo-solidifying it with a gelling agent or a cross-linking polymer, as in the case of use in a non-aqueous electrolyte battery called a lithium polymer battery.

[0153] lithium secondary battery

[0154] Furthermore, in one embodiment of the present invention,

[0155] An electrode assembly comprising: a positive electrode comprising one or more positive active materials among lithium metal oxides represented by the following chemical formulas 2 and 3; a negative electrode; and a separator interposed between the positive electrode and the negative electrode, and

[0156] A lithium secondary battery comprising an electrolyte composition according to the present invention is provided:

[0157] [Chemical Formula 2]

[0158] Li x [Ni y Co z Mn w M 1 v ]O2

[0159] [Chemical Formula 3]

[0160] LiM 2 p Mn (2-p) O4

[0161] In the above chemical formulas 2 and 3,

[0162] M 1It is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and

[0163] x, y, z, w, and v are 1.0≤x≤1.30, 0.5≤y<1, 0, respectively. <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고,

[0164] M 2 is Ni, Co, or Fe, and

[0165] p is 0.05≤p≤0.6.

[0167] A lithium secondary battery according to the present invention comprises a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and a lithium salt-containing non-aqueous electrolyte composition of the present invention as described above.

[0168] Specifically, the anode comprises an anode composite layer manufactured by applying, drying, and pressing an anode active material onto an anode current collector, and may optionally further include a conductive material, a binder, other additives, etc., as needed.

[0169] Here, the positive active material is a material capable of causing an electrochemical reaction on a positive current collector and may include one or more of the lithium metal oxides represented by Chemical Formula 2 and Chemical Formula 3 that are capable of reversibly intercalating and deintercalating lithium ions.

[0170] The lithium metal oxides represented by the above chemical formulas 2 and 3 are materials containing high amounts of nickel (Ni) and manganese (Mn), respectively, and when used as cathode active materials, they have the advantage of being able to stably supply high capacity and / or high voltage electricity.

[0171] In this case, LiNi is used as the lithium metal oxide represented by the above chemical formula 2. 0.8 Co0.1 Mn 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2, LiNi 0.6 Co 0.2 Mn 0.1 Al 0.1 O2, LiNi 0.6 Co 0.2 Mn 0.15 Al 0.05 O2, LiNi 0.7 Co 0.1 Mn 0.1 Al 0.1 The lithium metal oxide represented by the above chemical formula 3 may include O2, etc., and is LiNi 0.7 Mn 1.3 O4; LiNi 0.5 Mn 1.5 O4; LiNi 0.3 Mn 1.7 It may include O4, etc., and can be used alone or in combination.

[0172] In addition, the above-mentioned positive electrode may be used as a positive electrode current collector that has high conductivity without causing chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, etc. may be used, and in the case of aluminum or stainless steel, surface-treated materials such as carbon, nickel, titanium, silver, etc. may be used. Furthermore, the average thickness of the above-mentioned current collector may be appropriately applied in the range of 3 to 500 μm, taking into consideration the conductivity and total thickness of the manufactured positive electrode.

[0173] In addition, the above-mentioned cathode, like the anode, comprises a cathode composite layer manufactured by applying, drying, and pressing a cathode active material onto a cathode current collector, and may optionally further include a conductive material, a binder, other additives, etc., as needed.

[0174] The above-mentioned cathode active material may include carbon materials and silicon materials. Specifically, the carbon material refers to a material having carbon atoms as its main component, and such carbon materials may include one or more selected from the group consisting of natural graphite, artificial graphite, expanded graphite, non-graphitized carbon, carbon black, acetylene black, and Ketjen black. In addition, the silicon material refers to a material having silicon atoms as its main component, and such silicon materials may include silicon (Si), silicon carbide (SiC), silicon monoxide (SiO), or silicon dioxide (SiO2) alone or in combination. When silicon monoxide (SiO) and silicon dioxide (SiO2) are uniformly mixed or composited as silicon (Si)-containing materials and included in the cathode composite layer, they may be represented as silicon oxide (SiOq, provided that 0.8≤q≤2.5).

[0175] In addition, the silicon material may be included in an amount of 1 to 20 weight% with respect to the total weight of the negative electrode active material, and specifically, may be included in an amount of 3 to 10 weight%; 8 to 15 weight%; 13 to 18 weight%; or 2 to 8 weight%. The present invention can maximize the energy density of the battery by controlling the content of the silicon material to the above-mentioned content range.

[0176] In addition, the above-mentioned negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, nickel, titanium, calcined carbon, etc. may be used, and in the case of copper or stainless steel, surface-treated carbon, nickel, titanium, silver, etc. may be used. Furthermore, the average thickness of the above-mentioned negative electrode current collector can be appropriately applied in the range of 1 to 500 μm, taking into consideration the conductivity and total thickness of the negative electrode being manufactured.

[0177] Meanwhile, the separator interposed between the anode and the cathode of each unit cell is an insulating thin film having high ion permeability and mechanical strength, and is not particularly limited as long as it is commonly used in the industry, but specifically, it may be used that comprises one or more polymers selected from chemically resistant and hydrophobic polypropylene; polyethylene; and polyethylene-propylene copolymer. The separator may have the form of a porous polymer substrate such as a sheet or nonwoven fabric containing the aforementioned polymer, and in some cases, it may have the form of a composite separator in which organic or inorganic particles are coated on the porous polymer substrate by an organic binder. In addition, the separator may have an average pore diameter of 0.01 to 10 μm and an average thickness of 5 to 300 μm.

[0178] Furthermore, the secondary battery comprises, as an electrolyte, a non-aqueous electrolyte composition according to the present invention described above.

[0179] The above electrolyte composition comprises, as an electrolyte additive, an ionic compound represented by the following chemical formula 1, having a core having a (meth)acrylate group or a (meth)acrylamide group bonded to one side of a sulfonylimide group through a functional group having a conjugated structure, or a functional group having a structure in which a heteroatom is introduced to the sulfonylimide group:

[0180] [Chemical Formula 1]

[0181]

[0182] In the above chemical formula 1,

[0183] R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0184] R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms containing one or more heteroatoms among N, S, and O, and

[0185] R3 is a fluoro group, a C1- to C10 alkyl group, a C1- to C10 alkoxy group, or However,

[0186] The above alkyl group, alkoxy group and One or more of the hydrogen atoms contained in can be replaced with fluorine atoms, and

[0187] X is an oxygen atom (O) or -NR4, and R4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and

[0188] M comprises one or more selected from the group consisting of lithium, sodium, potassium, tetraalkylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, and

[0189] l is an integer from 1 to 6, and

[0190] m is an integer from 2 to 20.

[0192] The above compound has a structure represented by Chemical Formula 1, thereby enabling the uniform formation of an organic and / or inorganic film on the surface of the positive electrode and / or negative electrode upon activation of a secondary battery containing it. Through this, the electrolyte additive can suppress the decomposition of the electrolyte and the generation of gas when the battery is exposed to high temperatures, and can improve the decrease in OCV and capacity of the battery occurring at the positive electrode, thereby further enhancing the performance and high-temperature safety of the battery.

[0194] To this end, in the compound represented by the above chemical formula 1,

[0195] R1 is hydrogen, a methyl group, an ethyl group, or a propyl group, and

[0196] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0197] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0198] X is an oxygen atom (O), -NH, -NCH3 or -NCH2CH3, and

[0199] M comprises one or more selected from the group consisting of lithium, sodium, tetramethylammonium having 1 to 4 carbon atoms, and tetraalkylphosphonium having 1 to 4 carbon atoms, l is an integer from 1 to 6, and m is an integer from 2 to 20.

[0201] Specifically, R1 is hydrogen or a methyl group, and

[0202] R2 is a phenylene group, naphthalene group, anthracenylene group, biphenylene group, phenyleneoxy group, pyridinylene group, thiophenylene group, dioxolene group, or dithiolene group, and

[0203] R3 is a fluoro group, methyl group, ethyl group, propyl group, methoxy group, ethoxy group, or And,

[0204] X is an oxygen atom (O), -NH or -NCH3, and

[0205] M is lithium, l is an integer of 1 or 2, and m can be an integer from 2 to 10.

[0207] As an example, the compound represented by the above chemical formula 1 may be one or more of the following <Structural Formula 1> to <Structural Formula 48>:

[0208]

[0211] The present invention will be explained in more detail below through examples and experimental examples.

[0212] However, the following examples and experimental examples are merely illustrative of the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

[0214] Examples 1–5 and Comparative Examples 1–6. Preparation of electrolyte compositions for lithium secondary batteries

[0215] A non-aqueous electrolyte composition was prepared by dissolving LiPF6 as a lithium salt at a concentration of 1M in a solvent mixed with ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a 3:7 volume ratio, and by weighing and dissolving an electrolyte additive based on the total weight of the electrolyte as shown in Table 1 below.

[0216] Types of non-aqueous electrolyte additives Content Example 1 <구조식 25> 2 wt% Example 2 0.001 wt% Example 3 10 wt% Example 4 <구조식 26> 2 wt% Example 5 <구조식 29> 2 wt% Example 6 <구조식 31> 2 wt% Example 7 <구조식 33> 2 wt% Comparative Example 1 No additives - Comparative Example 2 <구조식 49> 2 wt% Comparative Example 3 <구조식 50> 2 wt% Comparative Example 4 <구조식 51> 2 wt% Comparative Example 5 <구조식 52> 2 wt% Comparative Example 6 <구조식 53> 2 wt%

[0218] Comparative Example 7. Preparation of an electrolyte composition for a lithium secondary battery

[0219] A non-aqueous electrolyte composition for a lithium secondary battery was prepared by performing the same method as in Example 1, except that an oligomer (weight-average molecular weight: 2,500 to 5,000) obtained by polymerizing a compound represented by the following structural formula 25 was used instead of the compound represented by structural formula 25 as an electrolyte additive.

[0221] Examples 8–14 and Comparative Examples 8–14. Preparation of lithium secondary batteries

[0222] LiNi with a particle size of 5㎛ as a cathode active material 0.5 Mn 1.5 O4 was prepared, and a slurry was formed by mixing it with N-methylpyrrolidone (NMP) in a weight ratio of 94:3:3 as a carbon-based conductive agent and binder, and then casting it onto an aluminum foil, drying it in a vacuum oven at 120°C, and rolling it to produce an anode.

[0223] Separately, a negative electrode active material was prepared in which artificial graphite and silicon oxide (SiO2) were mixed in a weight ratio of 9:1, and 97 parts by weight of the negative electrode active material and 3 parts by weight of styrene-butadiene rubber (SBR) were mixed with water to form a slurry, cast onto a copper foil, dried in a vacuum oven at 130°C, and then rolled to manufacture a negative electrode.

[0224] A separator made of 18 μm polypropylene was interposed between the anode and cathode obtained above, inserted into a case, and then an electrolyte composition prepared in Examples 1 to 7 and Comparative Examples 1 to 7 was injected as shown in Table 2 below to manufacture a lithium secondary battery.

[0225] Types of electrolyte compositions Example 8 Electrolyte composition of Example 1 Example 9 Electrolyte composition of Example 2 Example 10 Electrolyte composition of Example 3 Example 11 Electrolyte composition of Example 4 Example 12 Electrolyte composition of Example 5 Example 13 Electrolyte composition of Example 6 Example 14 Electrolyte composition of Example 7 Comparative Example 8 Electrolyte composition of Comparative Example 1 Comparative Example 9 Electrolyte composition of Comparative Example 2 Comparative Example 10 Electrolyte composition of Comparative Example 3 Comparative Example 11 Electrolyte composition of Comparative Example 4 Comparative Example 12 Electrolyte composition of Comparative Example 5 Comparative Example 13 Electrolyte composition of Comparative Example 6 Comparative Example 14 Electrolyte composition of Comparative Example 7

[0228] Experimental Example 1.

[0229] In order to analyze the form in which the electrolyte composition for a lithium ion battery according to the present invention exists in a secondary battery, the following experiments were performed on the electrolyte compositions prepared in Example 1 and Comparative Examples 1 and 7, respectively.

[0231] a) Raman spectroscopic analysis

[0232] 650–760 cm using a 532 nm laser on the electrolyte composition (5 ml) prepared in Example 1 -1 Raman spectroscopic analysis was performed in the wavelength range.

[0233] As a result, the electrolyte composition of the example containing the electrolyte additive represented by Formula 1 according to the present invention yielded 743±1 cm compared to the electrolyte composition prepared in Comparative Example 1 which does not contain the electrolyte additive. -1 It was confirmed that the band intensity of the Raman spectrum increased in the vicinity. This is due to the negatively charged nitrogen atoms contained in the sulfonylimide of the electrolyte additive represented by Chemical Formula 1 and the positively charged lithium ions (Li + This is a phenomenon exhibited by the formation of coordination bonds between ionic substances, meaning that the electrolyte composition of Example 1 contains an ionic compound. In addition, the increase in band intensity as described above indicates that the ionic compound can cause a reduction reaction on the cathode surface.

[0235] b) Analysis of the differential capacity curve of the half-cell

[0236] A half-cell was fabricated using lithium metal and graphite (a mixture of artificial graphite and natural graphite in a weight ratio of 9:1), and the electrolyte compositions prepared in Example 1 and Comparative Examples 1 and 7 were injected into the half-cell, respectively. Then, the battery was charged to 0.05V at a rate of 0.005C at 3.5±0.5V at 25℃, and after measuring the potential value (V) and capacity value (mAh), the reduction potential value was determined by differentiating the capacity value relative to the potential value (dQ / dV).

[0237] As a result, it was confirmed that the electrolyte composition of the example containing the electrolyte additive represented by Formula 1 according to the present invention exhibits a downward peak at a voltage of approximately 1.40 V relative to lithium, unlike the electrolyte composition of the comparative example that does not contain the electrolyte additive. The downward peak indicates that a reduction reaction occurred on the surface of the graphite electrode, which is the cathode, and indicates that the electrolyte additive represented by Formula 1 included in the electrolyte composition is converted into a film material through a reduction reaction on the cathode surface at approximately 1.40 V relative to lithium.

[0239] c) Linear Scan Potential Evaluation of a Three-Electrode Cell

[0240] Three-electrode cells were fabricated by injecting the electrolyte compositions prepared in Example 1 and Comparative Examples 1 and 7, respectively, into a cell comprising a platinum electrode, a platinum electrode, and a lithium metal electrode as three electrodes, and linear scanning potential (LSV) analysis was performed on each fabricated cell. At this time, the linear scanning potential (LSV) was performed under conditions of an observation range of 3.0 to 6.0 V (lithium reference), a step voltage of 50 mV, and a measurement rate of 50 mV / s.

[0241] As a result, it can be seen that the current of the electrolyte composition of the example containing the electrolyte additive represented by Formula 1 according to the present invention increases at around 4.0±0.05V relative to lithium. This implies that an oxidation reaction occurs on the lithium metal surface at around 4.0±0.05V, indicating that the electrolyte additive included in the electrolyte composition of Example 1 forms a film through an oxidation reaction on the anode surface when the condition is 4.0±0.05V or higher relative to lithium. Furthermore, it indicates that an oxidation reaction is induced at a lower potential than on the platinum electrode surface due to the catalytic properties of carbon or transition metals in the carbon electrode or anode electrode.

[0242] From these results, it can be seen that the electrolyte additive according to the present invention is an ionic substance that performs oxidation and reduction reactions at the positive and negative electrodes, respectively, during the charging and discharging of the battery, thereby forming a film on the surface of each electrode.

[0244] Experimental Example 2.

[0245] The following experiment was performed to analyze the film formed on the electrode surface upon activation of the lithium secondary battery according to the present invention and to evaluate the high-temperature safety of the lithium secondary battery. At this time, the lithium secondary batteries subjected to the experiment were each LiNi 0.6 Co 0.2 Mn 0.2 Secondary batteries of Examples 15–21 and Comparative Examples 15–21, prepared by performing the same method as Examples 8–14 and Comparative Examples 8–14 except that they contain O2 and artificial graphite, were used.

[0247] a) Analysis of the film on the electrode surface

[0248] For the secondary batteries of Example 15, Comparative Example 15, and Comparative Example 21, charge and discharge were performed three times each with a charge termination voltage of 4.2 V (NMC / graphite) and a discharge termination voltage of 2.5 V (NMC / graphite) at a charge / discharge current density of 0.33 C / 0.33 C, and X-ray photoelectron spectroscopy (XPS) was performed on the surfaces of the positive and negative electrodes of each battery in a fully discharged state.

[0249] As a result, the secondary battery (Example 15) containing the electrolyte composition of Example 1 was found to have peaks in the range of 280 to 300 eV, representing the binding energy of carbon and fluorine, on both the positive and negative electrodes during X-ray photoelectron spectroscopy (XPS) analysis of the electrode surfaces. Specifically, the positive and negative electrodes of the secondary battery showed a peak representing the binding energy of the CF3 group at 293 ± 0.2 eV, which means that the electrolyte additive represented by Formula 1 contained in the electrolyte composition participated in the formation of the film formed on the surfaces of the positive and negative electrodes. On the other hand, the secondary battery using the electrolyte composition of Comparative Example 1 that does not contain the electrolyte additive (Comparative Example 15) and the secondary battery using the electrolyte composition of Comparative Example 7 containing the electrolyte additive in the form of an oligomer (Comparative Example 21) were confirmed not to show a binding energy peak originating from the CF3 group on both the positive and negative electrodes.

[0250] From these results, it can be seen that the electrolyte additive according to the present invention can form a film on the electrode surface upon activation of a secondary battery by including a monomolecular ionic compound represented by Formula 1, having a core having a (meth)acrylate group or an acrylamide group bonded through a functional group having a structure in which a (meth)acrylate group or an acrylamide group is bonded through a cyclic unsaturated hydrocarbon group having a conjugated structure or a functional group in which a heteroatom is introduced to the cyclic unsaturated hydrocarbon group on one side centered on a sulfonylimide group.

[0252] b) Evaluation of high-temperature storage stability of secondary batteries

[0253] For each secondary battery, ① the amount of gas generated inside the secondary battery and ② the OCV of the secondary battery were observed over time while storing at 60°C for 56 days, and ③ the capacity retention rate before and after high-temperature storage was analyzed.

[0254] Specifically, each secondary battery was charged and discharged three times with a charge / discharge current density of 0.33C / 0.33C and a charge termination voltage of 4.2V (NMC / graphite) and 2.5V (NMC / graphite), respectively, to measure the battery capacity. After fully charging in CC / CV mode with a charge termination voltage of 4.2V at 0.33C, high-temperature storage was initiated. During this high-temperature storage, the batteries were kept in a 60°C constant temperature chamber for a total of 56 days. After 56 days, the OCV deviation before and after storage (i.e., the degree of OCV drop) and the capacity retention rate were measured, and the volume of gas generated within the secondary battery after high-temperature storage was measured using the Archimedes principle. The results are shown in Table 3 below.

[0255] Types of electrolyte additives used OCV deviation [mV] Capacity retention rate [%] Gas generation amount [µl] Example 15 <구조식 25> 32.9 98.0 1313 Example 16 35.7 96.5 1826 Example 17 36.3 96.8 1971 Example 18 <구조식 26> 33.2 97.9 1325 Example 19 <구조식 29> 33.5 97.9 1361 Example 20 <구조식 31> 34.0 97.3 1407 Example 21 <구조식 33> 32.8 97.5 1388 Comparative Example 15 No additives 38.5 95.6 2023 Comparative Example 16 <구조식 49> 40.0 95.0 1710 Comparative Example 17 <구조식 50> 39.6 95.4 1943 Comparative Example 18 <구조식 51> 35.6 96.9 1560 Comparative Example 19 <구조식 52> 38.1 95.8 1943 Comparative Example 20 <구조식 53> 39.6 96.1 1928 Comparative Example 21 Oligomer derived from <Structural Formula 25> 39.2 95.7 1877

[0257] As shown in Table 3 above, it can be seen that the secondary batteries of the example containing the compound represented by Formula 1 according to the present invention as an electrolyte additive significantly reduce the amount of gas generated and the decrease in OCV generated at the anode due to the film formed on the surface of the anode and cathode even when exposed to high temperature conditions, as the decomposition of the electrolyte is reduced.

[0259] 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 art will understand that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the invention as described in the claims set forth below.

[0260] Therefore, 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

Claim 1 Electrolyte additive for secondary batteries comprising a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms comprising one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms comprising one or more heteroatoms among N, S, and O, and R3 comprises a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or However, the above alkyl group, alkoxy group and One or more of the hydrogens included in may be substituted with fluorine atoms, X is an oxygen atom (O) or -NR4, R4 is hydrogen or a carbon-1 to carbon-4 alkyl group, M includes one or more selected from the group consisting of lithium, sodium, potassium, carbon-1 to carbon-4 tetraalkylammonium and carbon-1 to carbon-4 tetraalkylphosphonium, l is an integer from 1 to 6, and m is an integer from 2 to 20. Claim 2 In claim 1, R1 is hydrogen or a methyl group, R2 is a phenylene group, a naphthalene group, anthracenylene group, a biphenylene group, a phenyleneoxy group, a pyridinylene group, a thiophenylene group, a dioxolene group, or a dithiolene group, and R3 is a fluoro group, a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, or An electrolyte additive for a secondary battery, wherein X is an oxygen atom (O), -NH or -NCH3, M is lithium, l is an integer of 1 or 2, and m is an integer from 2 to 10. Claim 3 In claim 1, the compound represented by Chemical Formula 1 is an electrolyte additive for a secondary battery that is one or more of the following <Structural Formula 1> to <Structural Formula 48>: Claim 4 Electrolyte composition for a lithium secondary battery comprising: a non-aqueous organic solvent; a lithium salt; and a compound represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, R1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R2 comprises an arylene group having 6 to 20 carbon atoms; an aryleneoxy group having 6 to 20 carbon atoms; a heteroarylene group having 5 to 10 carbon atoms comprising one or more heteroatoms among N, S, and O; or a heteroaryleneoxy group having 5 to 10 carbon atoms comprising one or more heteroatoms among N, S, and O, and R3 comprises a fluoro group, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or However, the above alkyl group, alkoxy group and One or more of the hydrogens included in may be substituted with fluorine atoms, X is an oxygen atom (O) or -NR4, R4 is hydrogen or a carbon-1 to carbon-4 alkyl group, M includes one or more selected from the group consisting of lithium, sodium, potassium, carbon-1 to carbon-4 tetraalkylammonium and carbon-1 to carbon-4 tetraalkylphosphonium, l is an integer from 1 to 6, and m is an integer from 2 to 20. Claim 5 In claim 4, the electrolyte composition for a lithium secondary battery comprises a compound represented by Chemical Formula 1 in an amount of 0.01 to 3 weight% based on the total weight of the electrolyte composition. Claim 6 In paragraph 4, the lithium salt is LiCl, LiBr, LiI, LiClO4, LiBF4, LiB10Cl 10 An electrolyte composition for a lithium secondary battery comprising one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi, and (FSO2)2NLi. Claim 7 In claim 4, the above-mentioned non-aqueous organic solvent comprises one or more of N-methyl-2-pyrrolidinone, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolone, formamide, dimethylformamide, dioxolone, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate tryster, trimethoxymethane, dioxolone derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether, methyl propionate, and ethyl propionate, forming an electrolyte composition for a lithium secondary battery. Claim 8 A lithium secondary battery comprising: an electrode assembly comprising one or more positive active materials among lithium metal oxides represented by the following chemical formulas 2 and 3; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte composition according to claim 4: [Chemical Formula 2]Li x [Ni y Co z Mn w M 1 v ]O2[Chemical Formula 3]LiM 2 p Mn (2-p) O4 In the above chemical formulas 2 and 3, M 1 is one or more elements selected from the group consisting of W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and x, y, z, w, and v are 1.0≤x≤1.30, 0.5≤y<1, 0, respectively. <z≤0.3, 0<w≤0.3, 0≤v≤0.1이되, y+z+w+v=1이고,M 2 is Ni, Co, or Fe, and p is 0.05≤p≤0.

6. Claim 9 A lithium secondary battery according to claim 8, wherein the positive active material comprises one or more selected from the group consisting of LiNi0.8Co0.1Mn0.1O2, LiNi0.6Co0.2Mn0.2O2, LiNi0.9Co0.05Mn0.05O2, LiNi0.6Co0.2Mn0.1Al0.1O2, LiNi0.6Co0.2Mn0.15Al0.05O2, LiNi0.7Co0.1Mn0.1Al0.1O2, and LiNi0.5Mn1.5O4. Claim 10 A lithium secondary battery according to claim 8, wherein the negative electrode active material is composed of a carbon material and a silicon material, and the silicon material comprises one or more of silicon (Si), silicon carbide (SiC) and silicon oxide (SiOq, provided that 0.8≤q≤2.5). Claim 11 A lithium secondary battery according to claim 10, wherein the silicon material is included in an amount of 1 to 20 weight% relative to the total weight of the negative electrode active material.

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