Non-aqueous electrolyte for lithium secondary battery and lithium secondary battery containing the same

Abstract

The present invention relates to a non-aqueous electrolyte for a lithium secondary battery containing a compound represented by Chemical Formula 1, a lithium salt, and an organic solvent; and a lithium secondary battery including the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0085281 filed on July 11, 2022, and Korean Patent Application No. 10-2023-0086887 filed on July 5, 2023, and all of its contents are included herein.

[0002] The present invention relates to a non-aqueous electrolyte for a lithium secondary battery and a lithium secondary battery including the same.

Background Art

[0003] A lithium secondary battery is generally manufactured by forming an electrode assembly with a separator interposed between a positive electrode including a positive electrode active material made of a transition metal oxide containing lithium and a negative electrode including a negative electrode active material capable of storing lithium ions, inserting the electrode assembly into a battery case, injecting a non-aqueous electrolyte serving as a medium for transmitting lithium ions, and then sealing it.

[0004] Lithium secondary batteries can be miniaturized, have high energy density and operating voltage, and are applied to various fields such as mobile devices, electronic products, and electric vehicles. As the application fields of lithium secondary batteries become diverse, the required physical property conditions are gradually increasing. In particular, there is a demand for the development of lithium secondary batteries that can be stably driven even under high-temperature conditions and have long-life characteristics.

[0005] On the other hand, when a lithium secondary battery is driven under high-temperature conditions, PF6 - anions such as LiPF6 contained in the electrolyte may be thermally decomposed to generate Lewis acids such as PF5, which react with moisture to generate HF. Such decomposition products such as PF5 and HF not only destroy the film formed on the electrode surface, but may also cause a decomposition reaction of the organic solvent, react with the decomposition products of the positive electrode active material to elute transition metal ions, and the eluted transition metal ions may be electrodeposited on the negative electrode to destroy the film formed on the negative electrode surface.

[0006] If an electrolyte decomposition reaction persists on the film thus damaged, the performance of the battery further deteriorates. Therefore, there is a demand for the development of a secondary battery that can maintain excellent performance even under high-temperature conditions.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The present invention is for solving the above problems, and by including a compound derived from a pyrazole carboxylic acid substituted with R2, it is possible to form a stable film on an electrode and control metal elution, and through this, it aims to provide a non-aqueous electrolyte that can contribute to the improvement of the performance of a lithium secondary battery and a lithium secondary battery containing the same.

MEANS FOR SOLVING THE PROBLEMS

[0008] According to one embodiment, the present invention provides a non-aqueous electrolyte for a lithium secondary battery including a lithium salt; an organic solvent; and a compound represented by the following Chemical Formula 1.

[0009]

CHEM.

[0010] According to another embodiment, the present invention provides a lithium secondary battery including a positive electrode containing a positive electrode active material; a negative electrode containing a negative electrode active material; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte for the lithium secondary battery.

Advantages of the Invention

[0011] The non-aqueous electrolyte according to the present invention contains a compound represented by Chemical Formula 1 having a function of enhancing the positive electrode / negative electrode coating and controlling eluted metals, and thus can contribute to improving the high-temperature performance of the lithium secondary battery. In particular, since the compound contains a functional group based on fluorine, sulfur, or nitrogen in its structure, it can contribute to improving the stability and safety of the battery through the formation of an organic / inorganic composite coating. In addition, since interaction with transition metals is possible through the N and COO functional groups contained in the compound represented by Chemical Formula 1, it is possible to prevent the eluted metal from being electrodeposited on the negative electrode, and ultimately provide a lithium secondary battery with improved electrochemical characteristics.

Modes for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in more detail.

[0013] Generally, anions contained in lithium salts such as LiPF6 widely used in electrolytes for lithium secondary batteries form decomposition products such as hydrogen fluoride (HF) and PF5 due to thermal decomposition or moisture. Since such decomposition products have acidic properties, they deteriorate the coating or the electrode surface in the battery.

[0014] Due to the decomposition products of the electrolyte and the structural changes of the positive electrode caused by repeated charge and discharge, the transition metals in the positive electrode are easily eluted into the electrolyte. The eluted transition metals are re-deposited on the positive electrode again, increasing the resistance of the positive electrode. Moreover, when the eluted transition metals move to the negative electrode through the electrolyte, they may electrodeposit on the negative electrode to generate dendrites, causing the destruction of the SEI (solid electrolyte interphase) film and further electrolyte decomposition reactions, resulting in problems such as lithium ion consumption and increased resistance.

[0015] Also, protective films are formed on the positive and negative electrodes during the initial activation of the battery due to electrolyte reactions. However, when the films become unstable for the above reasons, further decomposition of the electrolyte occurs during charge and discharge or high-temperature exposure, accelerating battery deterioration and generating gas.

[0016] To solve such problems, the inventors of the present invention included a compound represented by the following Chemical Formula 1 in the non-aqueous electrolyte, and found that it has the effect of reducing the side reactions of the electrolyte at the positive / negative electrodes, suppressing the elution of transition metals, gas generation, and the increase in cell resistance. In particular, to ensure a high energy density, an increase in the driving voltage of the cell is indispensable. When the driving voltage increases, the above-mentioned performance degradation problems may become more serious. However, by applying the compound represented by Chemical Formula 1, such problems can be solved.

[0017] Hereinafter, each component constituting the present invention will be described in more detail.

[0018] Non-aqueous electrolyte The present invention provides a non-aqueous electrolyte for a lithium secondary battery containing a lithium salt; an organic solvent; and a compound represented by Chemical Formula 1.

[0019] Hereinafter, each component will be specifically described.

[0020] (1) Compound represented by Chemical Formula 1 The non-aqueous electrolyte of the present invention contains a compound represented by the following Chemical Formula 1.

[0021]

Chem.

[0022] Since the compound represented by Chemical Formula 1 contains an unshared electron pair at the bonding part (N-N) between the ester (-COO-) and the nitrogen in the pyrazole, stable film formation can be achieved through a strong bond with the transition metal on the positive electrode surface. Moreover, since it can also bond with metal ions through the unshared electron pair in the electrolyte, electrodeposition on the negative electrode can be prevented. In addition, when an ester functional group is included as in Chemical Formula 1 of the present application, since it is excellent in the ability to move Li through the unshared electron pair of oxygen during film formation, it is preferable in that a film useful for improving the output of the battery can be formed as compared with a structure in which a sulfonyl group, an F-based substituent, etc. are directly substituted for pyrazole.

[0023] In one embodiment of the present invention, R1 of Chemical Formula 1 may be an alkyl group having 1 to 5 carbon atoms or a nitrile group, and specifically, may be a methyl group or a nitrile group. When an alkyl group or a nitrile group is substituted in place of hydrogen at the position of R1, H by deprotonation +By preventing the increase, acidification of the electrolyte solution and side reactions induced thereby can be suppressed, which is effective in improving the durability of the battery. In particular, when a nitrile group is substituted, it is more preferable in that the effect of metal ion scavenging can be further expected due to the lone pair of electrons.

[0024] In one embodiment of the present invention, R2 in Chemical Formula 1 is an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, or an isocyanate group, preferably a methyl group, a trifluoromethyl group, or an isocyanate group. When R2 is hydrogen, there is a problem that the acidity of the electrolyte solution increases due to deprotonation in which -COOH and H + are eliminated.

[0025] In one embodiment of the present invention, R3 in Chemical Formula 1 is an alkyl group having 1 to 10 carbon atoms substituted with fluorine, specifically, an alkyl group having 1 to 5 carbon atoms substituted with fluorine, and more specifically, it may be a trifluoromethyl group.

[0026] In one embodiment of the present invention, n in Chemical Formula 1 may be 0 or 1, preferably n = 1. Compared with the case where n = 0 in Chemical Formula 1, when n = 1, a film with improved high-temperature performance may be formed. Specifically, when fluorine is contained in the structure, the oxidation stability is improved, which means that a stable film is formed on the positive electrode. When an unstable film is formed on the positive electrode, the performance may be reduced due to the decomposition reaction of the electrolyte solution under high voltage, but there is an effect of preventing this. In addition, since a film containing fluorine is formed during reduction at the negative electrode, it can be combined with the organic film formed by pyrazole to form an organic / inorganic composite film. That is, it is preferable in that an SEI is formed in which the effect of improving the life performance of the organic film and the advantage of the strong durability of the inorganic film are both exhibited.

[0027] In one embodiment of the present invention, the compound represented by Chemical Formula 1 may be represented by the following Chemical Formula 1-1 or Chemical Formula 1-2.

[0028]

Chem.

[0029]

Chem.

[0030] In one embodiment of the present invention, the above Chemical Formula 1 may be represented by any one of the following Chemical Formulas 1A to 1F.

[0031]

Chem.

[0032]

Chem.

[0033]

Chem.

[0034]

Chem.

[0035]

Chem.

[0036]

Chem.

[0037] In one embodiment of the present invention, the content of the compound represented by Chemical Formula 1 may be from 0.01% by weight to 15% by weight, preferably from 0.03% by weight to 12% by weight, and more preferably from 0.05% by weight to 10% by weight based on the total weight of the non-aqueous electrolyte.

[0038] When the content of the compound represented by Chemical Formula 1 is 0.01% by weight or more, the above-described effects can be realized. When it is 15% by weight or less, it is preferable in terms of preventing a decrease in the ionic conductivity of the non-aqueous electrolyte and preventing the formation of a non-uniform film on the electrode surface or an increase in side reactions.

[0039] (2) Additive The non-aqueous electrolyte of the present invention can further selectively contain an additive as necessary in order to prevent the electrolyte from being decomposed in a high-voltage environment and inducing electrode collapse, and to further improve effects such as low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and suppression of battery swelling at high temperatures.

[0040] The additive may be one or more selected from the group consisting of cyclic carbonate compounds, sultone compounds, sulfate compounds, phosphorus compounds, nitrile compounds, amine compounds, silane compounds, benzene compounds, and lithium salt compounds.

[0041] The cyclic carbonate compound may be one or more selected from the group consisting of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and fluoroethylene carbonate (FEC), and specifically may be vinylene carbonate.

[0042] The sultone compound is a substance capable of forming a stable SEI film by a reduction reaction on the surface of the negative electrode, and may be one or more compounds selected from the group consisting of 1,3-propanesultone (PS), 1,4-butanesultone, ethenesultone, 1,3-propenesultone (PRS), 1,4-butenesultone, and 1-methyl-1,3-propenesultone, and specifically may be 1,3-propanesultone (PS).

[0043] The sulfate-based compound is a substance that can be electrically decomposed on the surface of the negative electrode to form a stable SEI film without cracks even during high-temperature storage, and may be one or more selected from the group consisting of ethylene sulfate (Ethylene Sulfate; Esa), trimethylene sulfate (Trimethylene sulfate; TMS), or methyl trimethylene sulfate (Methyl trimethylene sulfate; MTMS).

[0044] The phosphorus-based compound may be a phosphate-based or phosphite-based compound. Specifically, it may be one or more selected from the group consisting of tris(trimethylsilyl) phosphate, tris(trimethylsilyl) phosphite, tris(2,2,2-trifluoroethyl) phosphate, and tris(trifluoroethyl) phosphite.

[0045] The nitrile-based compound may be one or more selected from the group consisting of succinonitrile (SN), adiponitrile (ADN), acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, ethylene glycol bis(2-cyanoethyl) ether (ASA3), 1,3,6-hexanetricarbonitrile (HTCN), 1,4-dicyano-2-butene (DCB), and 1,2,3-tris(2-cyanoethyl) propane (TCEP).

[0046] The amine-based compound may be one or more selected from the group consisting of triethanolamine and ethylenediamine, and the silane-based compound may be tetravinylsilane.

[0047] The benzene-based compound may be at least one selected from the group consisting of monofluorobenzene, difluorobenzene, trifluorobenzene, and tetrafluorobenzene.

[0048] The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte, and may be at least one compound selected from the group consisting of lithium difluorophosphate (LiDFP; LiPO2F2), lithium bis(oxalato)borate (LiBOB; LiB(C2O4)2), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate, and lithium difluoro(bisoxalato)phosphate (LiDFOP).

[0049] Preferably, the non-aqueous electrolyte according to an embodiment of the present invention may further include at least one additive selected from the group consisting of vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propanesultone (PS), ethylene sulfate (ESa), lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiODFB), and lithium difluorophosphate (LiDFP). More preferably, it may include vinyl ethylene carbonate (VEC). In this case, there is an effect of suppressing the decomposition of the compound represented by Chemical Formula 1 of the present invention through rapid film formation on the positive and negative electrodes and increasing the residual amount of the compound that can bind to PF5. This is an effect caused by the unshared electron pair of nitrogen in the pyrazole structure. Since the unshared electron pair in the pyrazole structure acts as a Lewis base, further decomposition of PF5, which is a Lewis acid, can be prevented. Such decomposition of the Lewis acid induces side reactions and an increase in resistance due to by-products in the electrode film, which can be a factor in deteriorating the performance of the battery.

[0050] On the one hand, the content of the additive may be from 0.1% by weight to 10% by weight based on the total weight of the non-aqueous electrolyte, preferably from 0.3% by weight to 5% by weight, and more preferably from 0.3% by weight to 1% by weight. When the content of the additive is within the above range, there is an effect of suppressing side reactions through film formation on the positive electrode and the negative electrode.

[0051] (3) Organic solvent The non-aqueous electrolyte of the present invention contains an organic solvent.

[0052] As the organic solvent, various organic solvents usually used in lithium electrolytes may be used without limitation. For example, the organic solvent may be a cyclic carbonate-based solvent, a linear carbonate-based solvent, a linear ester-based solvent, a cyclic ester-based solvent, a nitrile-based solvent, or a mixture thereof, preferably contains a mixture of two or more selected from the group consisting of a cyclic carbonate-based solvent, a linear carbonate-based solvent, and a linear ester-based solvent, and more preferably contains a mixture of a cyclic carbonate-based solvent and a linear carbonate-based solvent.

[0053] The cyclic carbonate-based solvent has a high dielectric constant as a high-viscosity organic solvent and can well dissociate the lithium salt in the electrolyte. It may be one or more selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and preferably may contain ethylene carbonate (EC) or propylene carbonate (PC).

[0054] In addition, the linear carbonate-based solvent is an organic solvent having a low viscosity and a low dielectric constant, and may be one or more selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate. Preferably, it may contain ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or diethyl carbonate (DEC).

[0055] In order to produce an electrolyte solution having a high ionic conductivity, it is preferable to use a mixture of a cyclic carbonate-based solvent and a linear carbonate-based solvent as the organic solvent.

[0056] The linear ester-based solvent may be one or more selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate. Preferably, it may be methyl propionate, ethyl propionate, or propyl propionate.

[0057] The cyclic ester-based solvent may be one or more selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0058] The nitrile-based solvent may be one or more selected from the group consisting of succinonitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile. Preferably, it may be succinonitrile.

[0059] Among the total weight of the non-aqueous electrolyte, the remaining portion excluding other constituent components such as the compound represented by the chemical formula 1, the additive, and the lithium salt may all be an organic solvent unless otherwise specified.

[0060] (4) Lithium salt The non-aqueous electrolyte of the present invention contains a lithium salt.

[0061] The lithium salt may be used without limitation, such as those commonly used in electrolytes for lithium secondary batteries. Specifically, the lithium salt contains Li as a cation + and, as an anion, 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 - , BF2C2O4CHF - , PF4C2O4 - , PF2C4O8 - , PO2F2-, (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 -, CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - It may contain any one or more selected from the group consisting of.

[0062] Specifically, the lithium salt is LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiN(FSO2)2; LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate (LiSO3CF3), lithium difluorophosphite (LiPO2F2), lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiFOB), lithium difluoro(bisoxalate)phosphate (LiDFOP), lithium tetrafluoro(oxalate)phosphate (LiTFOP), and lithium fluoromalonate(difluoro)borate (LiFMDFB), and may be one or more selected from the group consisting of, and preferably, it may be LiPF6.

[0063] In one embodiment of the present invention, the concentration of the lithium salt in the non-aqueous organic solution containing the lithium salt and the organic solvent may be from 0.5 M to 4.0 M, specifically, from 0.5 M to 3.0 M, and more specifically, from 0.8 M to 2.0 M. When the concentration of the lithium salt is within the above range, while sufficiently ensuring the effects of improving low-temperature output and cycle characteristics, it is possible to prevent the viscosity and surface tension from becoming too high and obtain appropriate electrolyte impregnation properties.

[0064] Lithium secondary battery Next, the lithium secondary battery according to the present invention will be described.

[0065] The lithium secondary battery according to the present invention includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. At this time, the non-aqueous electrolyte is the non-aqueous electrolyte according to the present invention. Since the non-aqueous electrolyte has been described above, the description thereof will be omitted, and hereinafter, other components will be described.

[0066] (1) Positive electrode The positive electrode according to the present invention contains a positive electrode active material, and can be manufactured by coating a positive electrode slurry containing a positive electrode active material, a binder, a conductive material, a solvent, etc. on a positive electrode current collector, and then drying and rolling.

[0067] The positive electrode current collector is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, stainless steel; aluminum; nickel; titanium; fired carbon; or those obtained by surface-treating the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used.

[0068] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and is one or more selected from the group consisting of LCO (LiCoO2); LNO (LiNiO2); LMO (LiMnO2); LiMn2O4, LiCoPO4; LFP (LiFePO4); and lithium composite transition metal oxides containing nickel (Ni), cobalt (Co), and manganese (Mn). For example, Li(Ni p Co q Mn r1 )O2 (0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) represented by lithium-nickel-manganese-cobalt-based oxide, Li(Ni p1 Co q1 Mn r2 )O4 (0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2) represented by lithium-nickel-manganese-cobalt-based oxide, or Li(Ni p2 Co q2 Mn r3 M S2)O2(M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, p2 + q2 + r3 + s2 = 1), and may be a lithium-nickel-cobalt-transition metal (M) oxide represented by

[0069] On the other hand, among the transition metals, the positive electrode active material may have a nickel molar ratio of 60 mol% or more, preferably 70 mol% or more, and more preferably 80 mol% or more.

[0070] In one embodiment of the present invention, the lithium composite transition metal oxide may be a compound represented by the following Chemical Formula 2. That is, the positive electrode active material according to one embodiment of the present invention may contain a lithium composite transition metal oxide represented by the following Chemical Formula 2.

[0071] [Chemical Formula 2] Li 1+x (Ni a Co b Mn c M d )O2 In the Chemical Formula 2, M is one or more 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, 1 + x, a, b, c, and d are atomic fractions of independent elements, respectively, -0.2 ≦ x ≦ 0.2, 0.6 ≦ a < 1, 0 < b ≦ 0.3, 0 < c ≦ 0.3, 0 ≦ d ≦ 0.1, and a + b + c + d = 1.

[0072] The 1 + x indicates the lithium molar ratio in the lithium composite transition metal oxide, and may be -0.1 ≦ x ≦ 0.2, or 0 ≦ x ≦ 0.2. When the lithium molar ratio satisfies the above range, the crystal structure of the lithium composite transition metal oxide can be stably formed.

[0073] Said a represents the molar ratio of nickel among all the metals excluding lithium in the lithium composite transition metal oxide, and may be 0.70 ≦ a < 1, 0.75 ≦ a < 1, or 0.80 ≦ a < 1. When the molar ratio of nickel satisfies the above range, it exhibits a high energy density and enables the realization of a high capacity.

[0074] Said b represents the cobalt molar ratio among all the metals excluding lithium in the lithium composite transition metal oxide, and may be 0 < b ≦ 0.20, 0 < b ≦ 0.18, or 0 < b ≦ 0.15. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0075] Said c represents the molar ratio of manganese among all the metals excluding lithium in the lithium composite transition metal oxide, and may be 0 < c ≦ 0.20, 0 < c ≦ 0.18, or 0 < c ≦ 0.15. When the molar ratio of manganese satisfies the above range, the structural stability of the positive electrode active material is excellently shown.

[0076] In one embodiment of the present invention, the lithium composite transition metal oxide may contain one or more doping 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. In other words, said d representing the molar ratio of the doping element among all the metals excluding lithium in the lithium composite transition metal oxide may be 0 < d ≦ 0.10, 0 < d ≦ 0.08, or 0 < d ≦ 0.05.

[0077] Preferably, a, b, c, and d in Chemical Formula 2 may be 0.70 ≦ a < 1, 0 < b ≦ 0.2, 0 < c ≦ 0.2, and 0 ≦ d ≦ 0.1, respectively.

[0078] In still another embodiment of the present invention, the lithium composite transition metal oxide is Li p Mn 1-q M q A2, Li p Mn2O 4-r X r 、Li pMn 2-q M q M’ r A4, Li p Co 1-q M q A2, Li p Co 1-q M q O 2-r X r , Li p Ni 1-q M q O 2-r X r , Li p Ni 1-q Co q O 2-r X r , Li p Ni 1-q-r Co q M r A w , Li p Ni 1-q-r Co q M r O 2-w X w , Li p Ni 1-q-r Mn q M r A w and Li p Ni 1-q-r Mn q M r O 2-w X w It is any one or more selected from the group consisting of, where p, q, r, and w are 0.9 ≦ p ≦ 1.2, 0 ≦ q ≦ 1, 0 ≦ r ≦ 1, and 0 ≦ w ≦ 2, respectively, M and M’ are the same as or different from each other, and are one or more elements selected from the group consisting of Mg, Al, Co, K, Na, Ca, Si, Ti, Sn, V, Ge, Ga, B, As, Zr, Mn, Cr, Fe, Sr, V, and rare earth elements; A is one or more elements selected from the group consisting of O, F, S, and P; and X is one or more elements selected from the group consisting of F, S, and P.

[0079] The positive electrode active material may be contained in an amount of 80% by weight to 99% by weight, specifically 90% by weight to 99% by weight, based on the total weight of the solid content in the positive electrode slurry. When the content of the positive electrode active material is 80% by weight or less, the energy density may be low and the capacity may decrease.

[0080] The binder is a component that assists in binding the active material, conductive material, etc. and binding to the current collector, and is usually added in an amount of 1% by weight to 30% by weight based on the total weight of the solid content in the positive electrode slurry.

[0081] Examples of such binders may include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sulfonated ethylene-propylene-diene polymer, styrene-butadiene rubber, fluororubber, or various copolymers thereof.

[0082] In addition, the conductive material is a substance that imparts conductivity without inducing a chemical change in the battery, and may be added in an amount of 0.5% by weight to 20% by weight based on the total weight of the solid content in the positive electrode slurry.

[0083] The conductive material may be selected from, for example, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; graphite powders such as natural graphite, artificial graphite, carbon nanotubes, and graphite; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, 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.

[0084] Further, the solvent of the positive electrode slurry may contain an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used so as to have a preferable viscosity when containing the positive electrode active material, binder, conductive material, etc. For example, the solid content concentration in the positive electrode slurry containing the positive electrode active material, binder, and conductive material may be included so as to be 40% by weight to 90% by weight, preferably 50% by weight to 80% by weight.

[0085] (2) Negative electrode The negative electrode according to the present invention contains a negative electrode active material, and can be manufactured by coating a negative electrode slurry containing the negative electrode active material, binder, conductive material, solvent, etc. on a negative electrode current collector, followed by drying and rolling.

[0086] The negative electrode current collector generally has a thickness of 3 μm to 500 μm. Such a negative electrode current collector is not particularly limited as long as it has high conductivity without inducing a chemical change in the battery. For example, copper; stainless steel; aluminum; nickel; titanium; fired carbon; a surface-treated one of copper or stainless steel with carbon, nickel, titanium, silver, etc.; or an aluminum-cadmium alloy, etc. may be used. Also, similar to the positive electrode current collector, fine irregularities can be formed on the surface to strengthen the binding force of the negative electrode active material, and it may be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric body, etc.

[0087] Further, the negative electrode active material can include one or more selected from the group consisting of 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; lithium metal; and a transition metal oxide.

[0088] As the carbonaceous material capable of reversibly intercalating / deintercalating the lithium ions, any carbonaceous negative electrode active material generally used in a lithium ion secondary battery can be used without particular limitation, and typical examples thereof include crystalline carbon, amorphous carbon, or both of them can be used. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, calcined coke and the like.

[0089] As the metal or an alloy of these metals and lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals and lithium may be used.

[0090] Examples of the metal composite oxide 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, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0<x≦1; 1≦y≦3; 1≦z≦8), and one or more selected from the group may be used.

[0091] As the substance capable of doping and undoping lithium, Si, SiO x(0 < x < 2), Si - Y alloy (wherein Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Si), Sn, SnO2, Sn - Y (wherein Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, and combinations thereof, and is not Sn), etc. can be mentioned, and at least one of these and SiO2 can also be mixed and used. The element Y may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (Dubnium), Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0092] Examples of the metal oxide include lithium - containing titanium composite oxide (LTO), vanadium oxide, lithium vanadium oxide, etc.

[0093] In one embodiment of the present invention, the negative electrode active material may be a mixture of the carbon - based material and the silicon - based material, and preferably may be a mixture of graphite and SiO.

[0094] The negative electrode active material may be contained in an amount of 80% by weight to 99% by weight based on the total weight of the solid content in the negative electrode slurry.

[0095] The binder is a component that aids in the bonding between the conductive material, the active material, and the current collector, and may usually be added in a content of 1 wt% to 30 wt% based on the total weight of the solid content in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer, sulfonated ethylene-propylene-diene polymer, styrene-butadiene rubber, fluororubber, or various copolymers thereof.

[0096] The conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 0.5 wt% to 20 wt% based on the total weight of the solid content in the negative electrode slurry. Such a conductive material is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; graphite powder such as natural graphite, artificial graphite, carbon nanotubes, and graphite; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, 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.

[0097] The solvent of the negative electrode slurry may contain water or an organic solvent such as NMP and alcohol, and may be used so as to have a preferable viscosity when containing the negative electrode active material, the binder, the conductive material, etc. For example, the solid content concentration in the slurry containing the negative electrode active material, the binder, and the conductive material may be included so as to be 30 wt% to 80 wt%, preferably 40 wt% to 70 wt%.

[0098] (3) Separator The lithium secondary battery according to the present invention includes a separator between the positive electrode and the negative electrode.

[0099] The separator separates the negative electrode from the positive electrode and provides a migration path for lithium ions. Generally, any separator can be used without particular limitation as long as it is used as a separator in a lithium secondary battery. In particular, a separator having low resistance to ion migration of the electrolyte solution, excellent electrolyte moisture retention ability, and excellent safety is preferable.

[0100] Specifically, as the separator, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a homopolymer of ethylene, a homopolymer of propylene, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer; or a laminate structure of two or more layers thereof may be used. Further, an ordinary porous nonwoven fabric, for example, a nonwoven fabric made of high-melting glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymer substance may be used, and it may be used in a single-layer or multi-layer structure.

[0101] The lithium secondary battery according to the present invention as described above may be usefully used in portable devices such as mobile phones, notebook computers, digital cameras; and in the field of electric vehicles such as hybrid electric vehicles (HEV).

[0102] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0103] The battery module or battery pack may be used as a power source for any one or more of the following medium to large-sized devices: a power tool; an electric vehicle (including an electric vehicle, an EV, a hybrid electric vehicle, and a plug-in hybrid electric vehicle, a PHEV); and a power storage system.

[0104] Although there is no particular limitation on the external shape of the lithium secondary battery of the present invention, it may be a cylindrical shape using a can, a rectangular shape, a pouch type, a coin type, or the like.

[0105] The lithium secondary battery according to the present invention is not only used for a battery cell used as a power source for a small device, but may also be preferably used as a unit battery of a medium to large-sized battery module including a large number of battery cells.

[0106] Hereinafter, the present invention will be specifically described through specific examples.

[0107] <Example: Manufacture of Lithium Secondary Battery> Example 1. 1) Manufacture of non-aqueous electrolyte Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 30:70, and then LiPF6 was dissolved to a concentration of 1M to produce a non-aqueous organic solution. 0.05 wt% of the compound represented by Chemical Formula 1A and the remaining non-aqueous organic solution were mixed to produce 100 wt% of a non-aqueous electrolyte.

[0108] 2) Manufacture of lithium secondary battery Li(Ni 0.8 Co 0.1 Mn 0.1Oxygen (O₂), a conductive material (carbon black), and a binder (polyvinylidene fluoride) were added in a weight ratio of 98:1:1 to produce a positive electrode slurry (solid content: 60 wt%). After applying and drying the positive electrode slurry onto an aluminum (Al) thin film, which is a positive electrode current collector with a thickness of 15 μm, a roll press was performed to produce a positive electrode.

[0109] Graphite was used as the negative electrode active material, SBR-CMC as the binder, and carbon black as the conductive material. They were added to water, which is the solvent, in a weight ratio of 95:3.5:1.5 to produce a negative electrode slurry (solid content: 60 wt%). After applying and drying the negative electrode slurry onto a copper (Cu) thin film, which is a negative electrode current collector with a thickness of 10 μm, a roll press was performed to produce a negative electrode.

[0110] The positive electrode, a polyolefin-based porous separator coated with inorganic particles (Al₂O₃), and the negative electrode were sequentially laminated to produce an electrode assembly.

[0111] The assembled electrode assembly was housed in a pouch-type battery case, and 5 mL of the manufactured non-aqueous electrolyte was injected to produce a lithium secondary battery.

[0112] Example 2. A lithium secondary battery was produced in the same manner as in Example 1, except that 0.5 wt% of vinyl ethylene carbonate (VEC) was further added during the production of the non-aqueous electrolyte.

[0113] Example 3. A lithium secondary battery was produced in the same manner as in Example 1, except that the content of the compound represented by Chemical Formula 1A was changed to 10 wt% during the production of the non-aqueous electrolyte.

[0114] Example 4. A lithium secondary battery was produced in the same manner as in Example 3, except that 0.5 wt% of vinyl ethylene carbonate (VEC) was further added during the production of the non-aqueous electrolyte.

[0115] Example 5. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1B was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0116] Example 6. A lithium secondary battery was manufactured in the same manner as in Example 5, except that the content of the compound represented by Chemical Formula 1B was changed to 10 wt% during the production of the non-aqueous electrolyte.

[0117] Example 7. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1C was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0118] Example 8. A lithium secondary battery was manufactured in the same manner as in Example 7, except that the content of the compound represented by Chemical Formula 1C was changed to 10 wt% during the production of the non-aqueous electrolyte.

[0119] Example 9. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1D was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0120] Example 10. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1E was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0121] Example 11. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1F was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0122] Comparative Example 1. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula 1A was not added during the production of the non-aqueous electrolyte.

[0123] Comparative Example 2. A lithium secondary battery was manufactured in the same manner as in Comparative Example 1, except that 0.5 wt% of vinyl ethylene carbonate (VEC) was further added during the production of the non-aqueous electrolyte.

[0124] Comparative Example 3. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula Z1 below was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0125]

Chem.

[0126] Comparative Example 4. A lithium secondary battery was manufactured in the same manner as in Comparative Example 3, except that the content of the compound represented by Chemical Formula Z1 was changed to 10 wt% during the production of the non-aqueous electrolyte.

[0127] Comparative Example 5. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the compound represented by Chemical Formula Z2 below was used instead of the compound represented by Chemical Formula 1A during the production of the non-aqueous electrolyte.

[0128]

Chem.

[0129] Comparative Example 6. A lithium secondary battery was manufactured in the same manner as in Comparative Example 5, except that the content of the compound represented by Chemical Formula Z2 was changed to 10 wt% during the production of the non-aqueous electrolyte.

[0130] Comparative Example 7. A lithium secondary battery was manufactured in the same manner as in Comparative Example 6, except that a compound represented by the following chemical formula Z3 was used instead of the compound represented by the chemical formula Z2 during the production of the non-aqueous electrolyte.

[0131]

Chem.

[0132] <Experimental Example: Evaluation of Battery Performance> Experimental Example 1. Measurement of Capacity and Resistance after High-Temperature Storage After performing an activation process on the lithium secondary batteries manufactured in the above Examples and Comparative Examples, constant current / constant voltage (CC / CV) charging (0.05C cut off) was performed at 25°C at a 0.33C rate up to 4.25V, and constant current (CC) discharging was performed at a 0.33C rate down to 2.50V. Then, the initial discharge capacity was measured. Based on the measured discharge capacity, the state of charge was set to SOC50%, and the initial resistance was confirmed by measuring the voltage drop that appears when a discharge pulse is applied at a constant current of 2.5C for 10 seconds.

[0133] Thereafter, the battery was fully charged to SOC100% under the same conditions and stored at a high temperature (60°C) for 8 weeks. Then, after transferring it to a charge / discharge machine at room temperature (25°C), the capacity and resistance were measured again, and the capacity retention rate and resistance increase rate were calculated through the following Formula 1 and Formula 2, and the results are shown in Table 1 below. Formula 1: Capacity retention rate (%) = (Discharge capacity after high-temperature storage / Initial discharge capacity) × 100 Formula 2: Resistance increase rate (%) = {(Resistance after high-temperature storage - Initial resistance) / Initial resistance} × 100

[0134] Experimental Example 2. Measurement of Gas Generation Amount after High-Temperature Storage After performing the formation process on the lithium secondary batteries manufactured in the above Examples and Comparative Examples, charging was carried out under constant current / constant voltage conditions (0.05C cut off) up to 4.25V at a rate of 0.33C at 25°C until full charge to SOC100%. After storing the fully charged battery at 60°C for 8 weeks, it was transferred to a charger at room temperature (25°C), and the gas collected in the pouch was analyzed using GC-TCD (gas chromatography-thermal conductivity detector). The relative gas generation amount of each battery was calculated based on 100% of the gas generation amount measured in Comparative Example 1 and shown in Table 1 below.

[0135] Experimental Example 3. Evaluation of High-Temperature Life After performing the formation process on the lithium secondary batteries manufactured in the above Examples and Comparative Examples, constant current / constant voltage (CC / CV) charging (0.05C cut off) was carried out up to 4.25V at a rate of 0.33C at 45°C, and discharging was carried out at a constant current (CC) up to 2.5V at a rate of 0.33C.

[0136] Performing the above charge / discharge once each was defined as 1 cycle. After repeating the same charge / discharge 200 times, the capacity retention rate and the resistance increase rate (DCIR increase) were measured through the following Formulas 3 and 4. The measurement results are shown in Table 1 below. Formula 3: Capacity retention rate (%) = (Discharge capacity after 200 cycles / Discharge capacity after 1 cycle) × 100 Formula 4: Resistance increase rate (%) = { (Resistance after 200 cycles - Resistance after 1 cycle) / Resistance after 1 cycle} × 100

[0137] Experimental Example 4. Evaluation of Thermal Safety After performing the activation process on the lithium secondary batteries manufactured in the above Examples and Comparative Examples, charging (0.05C cut off) was carried out under constant current / constant voltage conditions up to 4.25V at a rate of 0.33C at 25°C until full charge to SOC100%. The fully charged battery was heated to 140°C at a heating rate of 5°C / min and then left for 1 hour each to conduct a hot box evaluation experiment to confirm whether ignition occurred.

[0138] The results were listed in Table 1 below and indicated as PASS if the battery did not catch fire and FAIL if it caught fire.

[0139]

Table 1

[0140] Through the results in Table 1 above, it can be confirmed that the batteries of Examples 1 to 11 to which the electrolyte containing the compound represented by Chemical Formula 1 was applied are superior in capacity and resistance characteristics after high-temperature storage compared to the batteries of Comparative Examples 1 to 7 to which the electrolyte not containing the compound represented by Chemical Formula 1 was applied, have less gas generation amount, and are excellent in life characteristics and safety at high temperatures.

[0141] In particular, even if the electrolytic solution contains a compound having a pyrazole structure, it can be confirmed that in the case of a compound in which the ester group is not substituted as in Chemical Formula Z1, a sulfonyl (-SO2-) group is substituted instead of the ester as in Chemical Formula Z2, or a carboxy group is substituted as in Chemical Formula Z3, the performance deteriorates significantly in all evaluation items. This is because the compound represented by Chemical Formula 1 contains an ester functional group and a lone pair of electrons at the nitrogen bonding part in pyrazole, and thus can form a stable film through a strong bond with the transition metal on the positive electrode surface. However, in the case of the comparative example, such an effect could not be obtained. Not only that, but the compound represented by Chemical Formula 1 can form a film useful for improving the output of the battery because the ability to move lithium is improved by the lone pair of electrons of oxygen. However, when a carboxy group is substituted as in Chemical Formula Z3, the acidification of the electrolytic solution and the side reactions caused thereby are induced while hydrogen ions are dissociated, so that the effects as in Chemical Formula 1 could not be obtained.

[0142] That is, it can be confirmed that the electrolytic solution containing the compound represented by Chemical Formula 1 as in the present invention has an effect of contributing to the improvement of the high-temperature storage and high-temperature life characteristics of the lithium secondary battery.

Claims

1. A non-aqueous electrolyte for a lithium secondary battery, comprising a lithium salt, an organic solvent, and a compound represented by the following Chemical Formula 1: 【Chemical 1】 In the Chemical Formula 1, L1 is a direct bond or an alkylene group having 1 to 10 carbon atoms, R1 is an alkyl group having 1 to 10 carbon atoms or a nitrile group, L2 is a direct bond, an alkylene group having 1 to 10 carbon atoms, an alkyleneoxy group having 1 to 10 carbon atoms, or a sulfonyl group, R2 is a fluorine-substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a nitrile group, or an isocyanate group, R3 is a fluorine-substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, n is any one integer from 0 to 2, and when n is 2, the two R3s are the same as or different from each other.

2. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein R2 in the Chemical Formula 1 is an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, or an isocyanate group.

3. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein R3 in the Chemical Formula 1 is a fluorine-substituted alkyl group having 1 to 10 carbon atoms.

4. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein the compound represented by the Chemical Formula 1 is represented by the following Chemical Formula 1-1 or the following Chemical Formula 1-2: 【Chemical 2】 [Chemical Formula 3] In the Chemical Formula 1-1 and the Chemical Formula 1-2, R1 to R3 are as defined in the Chemical Formula 1.

5. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein the content of the compound represented by the Chemical Formula 1 is 0.01% by weight to 15% by weight based on the total weight of the non-aqueous electrolyte.

6. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein the content of the compound represented by the Chemical Formula 1 is 0.05% by weight to 10% by weight based on the total weight of the non-aqueous electrolyte.

7. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, further comprising one or more additives selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, 1,3-propane sultone, ethylene sulfate, lithium tetrafluoroborate, lithium difluoro(oxalate) borate, and lithium difluorophosphate.

8. The non-aqueous electrolyte for a lithium secondary battery according to Claim 1, wherein the organic solvent contains a mixture of two or more selected from the group consisting of cyclic carbonate solvents, linear carbonate solvents, and linear ester solvents.

9. A positive electrode containing a positive electrode active material; A negative electrode containing a negative electrode active material; A separator interposed between the positive electrode and the negative electrode; and A lithium secondary battery containing the non-aqueous electrolyte according to any one of Claims 1 to 8.

10. The lithium secondary battery according to Claim 9, wherein the positive electrode active material contains a lithium composite transition metal oxide represented by the following Chemical Formula 2: [Chemical Formula 2] Li １＋ｘ (Ni ａ Co ｂ Mn ｃ M ｄ )O ２ In the Chemical Formula 2, M is one or more 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, 1 + x, a, b, c, and d are atomic fractions of independent elements, respectively, -0.2 ≤ x ≤ 0.2, 0.6 ≤ a < 1, 0 < b ≤ 0.3, 0 < c ≤ 0.3, 0 ≤ d ≤ 0.1, and a + b + c + d = 1.

11. The lithium secondary battery according to Claim 10, wherein a, b, c, and d in the Chemical Formula 2 are 0.70 ≤ a < 1, 0 < b ≤ 0.2, 0 < c ≤ 0.2, and 0 ≤ d ≤ 0.1, respectively.

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