Nonaqueous electrolyte and lithium secondary battery containing same

Abstract

The present invention relates to a nonaqueous electrolyte solution capable of forming a thin and stable SEI layer and improving the high-temperature stability and life characteristics of a lithium secondary battery, and relates to a nonaqueous electrolyte solution containing an organic solvent, a lithium salt, and one or more compounds selected from the group consisting of a compound represented by Chemical Formula I described in the present specification and compounds represented by Chemical Formulas II to V described in the present specification, and a lithium secondary battery containing the nonaqueous electrolyte solution.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0094116 dated July 28, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a non-aqueous electrolyte solution containing a silane-based compound, and a lithium secondary battery containing the same. [Background technology]

[0003] In recent years, the application areas of lithium secondary batteries have been rapidly expanding beyond power supply for electrical, electronic, communication, and computer electronic devices to power storage and supply for large-area devices such as automobiles and power storage devices. Accordingly, there has been an increasing demand for high-capacity, high-output, and highly stable secondary batteries.

[0004] Lithium secondary batteries are generally manufactured by coating a positive electrode active material made of lithium-containing transition metal oxide or a carbon-based or silicon-based negative electrode active material capable of intercalating and deintercalating lithium ions with a binder and a conductive material on a positive electrode collector and a negative electrode collector, respectively, to manufacture a positive electrode and a negative electrode, which are then laminated on both sides of a separator to form an electrode collector of a predetermined shape, and then inserting the electrode collector and a non-aqueous electrolyte into a battery case. In this case, formation and aging processes are almost always required to ensure the performance of the battery.

[0005] The formation process is a step of activating the secondary battery by repeatedly charging and discharging after the battery is assembled. During the charging process, lithium ions released from the lithium-containing transition metal oxide used as the positive electrode move to and are inserted into the carbon material negative electrode active material used as the negative electrode. At this time, the highly reactive lithium ions react with the electrolyte to form Li 2 CO 3 , Li 2The compounds, such as O, LiOH, etc., are generated on the surface of the electrode, and these compounds form a solid electrolyte interface (SEI) layer. The formation of the SEI layer is an important factor since the SEI layer closely affects the life and capacity maintenance.

[0006] In recent years, high capacity, high output, and long life characteristics have become important, especially for lithium secondary batteries for automobiles. In order to increase capacity, a positive electrode active material with high energy density but low stability is used, so it is necessary to form an active material-electrolyte interface that can protect the surface of the positive electrode active material and stabilize the positive electrode active material. On the other hand, a problem has been reported in which the surface species of the negative electrode are decomposed by the electrolyte and cause side reactions, so it is necessary to form a strong SEI layer with low resistance. In addition, since the SEI layer may gradually collapse during storage at high temperatures, causing problems such as electrode exposure, attempts have been made to develop additives in the electrolyte that help generate an SEI interface that can suppress side reactions during high-temperature storage.

[0007] As described above, as high-temperature operation and long-term life characteristics become important in lithium secondary batteries, electrolyte decomposition reactions due to oxidation-reduction reactions occurring at the interface between the electrolyte and the electrodes accumulate during repeated cycles, resulting in increased resistance, which causes a problem of deterioration of life characteristics. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide a nonaqueous electrolyte solution that is stable even at high temperatures and can form an electrode-electrolyte interface with low resistance, thereby improving the high-temperature stability and life characteristics of a lithium secondary battery, and a lithium secondary battery containing the same. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a nonaqueous electrolyte and a lithium secondary battery.

[0010] (1) The present invention provides a nonaqueous electrolyte solution comprising an organic solvent, a lithium salt, a compound represented by the following chemical formula I, and one or more compounds selected from the group consisting of compounds represented by the following chemical formulas II to V:

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[0014] [Chemical formula IV] Si(R'') 4

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[0016] In the above Chemical Formulae I to V, R a is C substituted with one or more fluorine atoms. 1 -C 10 is an alkyl group of the formula R b each independently represents a C which is substituted or not substituted with one or more fluorine atoms; 1 -C 10 is an alkyl group of the formula R c are each independently substituted or unsubstituted C 1 -C 10 is an alkyl group of the formula R' is independently hydrogen; 1 -C 10 or a substituted or unsubstituted C 1 -C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C 2 -C 10 or a substituted or unsubstituted C 2 -C 10 is an alkynyl group of the formula R d and R e are each independently hydrogen; 1 -C 10 Alkyl groups of substituted or unsubstituted C 1 -C 10 or a substituted or unsubstituted siloxane group, R d and R e When both of R d and R e may be linked to each other to form a ring consisting of a siloxane bond, n is 2 or 3.

[0017] (2) The present invention provides the nonaqueous electrolyte according to (1) above, wherein the compound represented by chemical formula I is one or more compounds selected from the compounds represented by the following chemical formulae Ia to If:

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[0024] (3) The present invention provides the nonaqueous electrolyte solution according to (1) or (2) above, wherein the compound represented by chemical formula II is one or more compounds selected from the compounds represented by the following chemical formulae II-a to II-f:

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[0031] (4) The present invention provides the nonaqueous electrolyte solution according to any one of (1) to (3) above, wherein the compound represented by chemical formula III is one or more compounds selected from the compounds represented by the following chemical formulae III-a to III-o:

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[0047] (5) The present invention provides the nonaqueous electrolyte solution according to any one of (1) to (4) above, wherein the compound represented by chemical formula IV is one or more compounds selected from the compounds represented by the following chemical formulae IV-a to IV-c:

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[0051] (6) The present invention provides the non-aqueous electrolyte according to any one of (1) to (5) above, wherein the compound represented by the chemical formula V is one or more compounds selected from the compounds represented by the following chemical formulas V-a and V-b.

[0052]

Chemical formula

[0053]

Chemical formula

[0054] (7) The present invention provides the non-aqueous electrolyte according to any one of (1) to (6) above, wherein the weight ratio of the compound represented by the chemical formula I to one or more compounds selected from the compounds represented by the chemical formulas II to V is 1 to 100:1.

[0055] (8) The present invention provides the non-aqueous electrolyte according to any one of (1) to (7) above, wherein the compound represented by the chemical formula I is contained in the non-aqueous electrolyte in an amount of 0.01 part by weight to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte.

[0056] (9) The present invention provides the non-aqueous electrolyte according to any one of (1) to (8) above, wherein one or more compounds selected from the compounds represented by the chemical formulas II to V are contained in the non-aqueous electrolyte in an amount of 0.01 part by weight to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte.

[0057] (10) 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 the non-aqueous electrolyte according to any one of (1) to (9) above.

[0058] (11) The present invention provides the lithium secondary battery according to (10) above, wherein the negative electrode active material is a silicon-based negative electrode active material.

Advantages of the Invention

[0059] In the case where the compound represented by the chemical formula I, which is a silane-based compound, and one or more compounds selected from the compounds represented by the chemical formulas II to V are contained as additives in the nonaqueous electrolyte solution as in the present invention, a thin and stable SEI layer is formed, and a lithium secondary battery having excellent high-temperature stability and life characteristics can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0060] The present invention will now be described in more detail.

[0061] The terms and words used in this specification and the claims should not be interpreted in a limited manner to their ordinary or dictionary meanings, but should be interpreted in a manner that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best describe their invention.

[0062] The terms used in the present invention are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be understood to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0063] non-aqueous electrolyte The present invention provides a nonaqueous electrolyte solution comprising an organic solvent, a lithium salt, a compound represented by the following chemical formula I, and one or more compounds selected from the group consisting of compounds represented by the following chemical formulas II to V:

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[0067] [Chemical formula IV] Si(R'') 4

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[0069] In the above Chemical Formulae I to V, R a is C substituted with one or more fluorine atoms. 1 -C 10 is an alkyl group of the formula R b each independently represents a C which is substituted or not substituted with one or more fluorine atoms; 1 -C 10 is an alkyl group of the formula R c are each independently substituted or unsubstituted C 1 -C 10 is an alkyl group of the formula R' is independently hydrogen; 1 -C 10 or a substituted or unsubstituted C 1 -C 10 is a heteroalkyl group of the formula R'' is a substituted or unsubstituted C 2 -C 10 or a substituted or unsubstituted C 2 -C 10 is an alkynyl group of the formula R d and R eare each independently hydrogen; 1 -C 10 Alkyl groups of the formula; substituted or unsubstituted C 1 -C 10 or a substituted or unsubstituted siloxane group, R d and R e When both of R d and R e may be linked to each other to form a ring consisting of a siloxane bond, n is 2 or 3.

[0070] In the present invention, in the case of a substituted alkyl group, a substituted heteroalkyl group, a substituted alkenyl group, a substituted alkynyl group, or a substituted siloxane group, the substituent may be a deuterium (-D), a hydroxyl group (-OH), an amino group (-NR 2 ), halogen group (-X), thiol group (-SR), cyano group (-CN), carbonyl group (-C(=O)-H, -C(=O)-R, -C(=O)-OH, -C(=O)-NR 2 , -C(=O)-OR, -C(=O)-X), carbamate group (-OC(=O)-NR 2 , -NR-C(=O)OR), urea group (-N(R)-C(=O)-NR 2 ), carbonate group (-OC(=O)-OR), anhydride group (-C(=O)-OC(=O)-R), ester group (-OC(=O)-R), cyanate group (-OCN), isocyanate group (-NCO), thiocyanate group (-SCN), nitrate group (-ON(=O)-OR), sulfonyl group (-S(=O) 2 -R), sulfinyl group (-S(=O)-R), phosphite (-OP(OR) 2 ), phosphate (-OPO(OR) 2 ), Phosphinate (-PO(OR)R), Phosphinite (-P(OR)R 2 ), Phosphonate (-PO 3 R 2), phosphonate (-P(OR) 2 ), Boronic Acid (-B(OR) 2 ), Borate, -OB(OR) 2 ), Borane (-BR 2 ), siloxane group (-Si-O-Si-R), silane group (-SiR 4 ), or linear or branched C 1 -C 6 In this case, in the substituent, X is a halogen group, and each R is independently an alkoxy group of C 1 -C 10 Alkyl group of C 2 -C 10 or C 2 -C 10 The alkynyl group may be:

[0071] (1) One or more compounds selected from the group consisting of a compound represented by chemical formula I and compounds represented by chemical formulas II to V The non-aqueous electrolyte according to the present invention contains, as an additive, the compound represented by the above chemical formula I, which is a silane-based compound, and one or more compounds selected from the compounds represented by the above chemical formulas II to V. That is, the nonaqueous electrolyte according to the present invention may contain both compounds represented by chemical formula I and chemical formula II, both compounds represented by chemical formula I and chemical formula III, both compounds represented by chemical formula I and chemical formula IV, both compounds represented by chemical formula I and chemical formula V, both compounds represented by chemical formula I, chemical formula II, and chemical formula III, both compounds represented by chemical formula I, chemical formula II, and chemical formula IV, both compounds represented by chemical formula I, chemical formula II, and chemical formula V, both compounds represented by chemical formula I, chemical formula III, and chemical formula IV, both compounds represented by chemical formula I, chemical formula III, and chemical formula V, both compounds represented by chemical formula I to IV, both compounds represented by chemical formula I, chemical formula II, chemical formula III, and chemical formula V, both compounds represented by chemical formula I, chemical formula II, chemical formula IV, and chemical formula V, or both compounds represented by chemical formula I, chemical formula III, chemical formula IV, and chemical formula V.

[0072] When the compound represented by the formula I and one or more compounds selected from the compounds represented by the formulas II to V are contained in a non-aqueous electrolyte, a thin and stable SEI layer is formed, and a lithium secondary battery having excellent high-temperature stability and life characteristics can be provided. In particular, when a silicon-based negative electrode material is used as the negative electrode of the lithium secondary battery, a thin and stable SEI layer containing not only siloxane bonds but also carbon-carbon bonds is formed, and the high-temperature stability and life characteristics of the battery can be further improved.

[0073] The compound represented by the formula I forms a covalent bond ([electrode]-O-Si-O-) with a hydroxy group (-OH) on the surface of the negative or positive electrode material, thereby forming an SEI layer with higher mechanical rigidity against volume change. In particular, when a silicon-based negative electrode material is applied, a siloxane network is formed, thereby protecting the silicon-based negative electrode, which has a large volume expansion during charging and discharging. In addition, since the compound represented by the formula I has a substituted or unsubstituted alkenyl group; or a substituted or unsubstituted alkynyl group, it can form a polymeric SEI layer by forming a CC bond through a reduction / oxidation decomposition reaction. In this case, since the compounds represented by the formulas II to V have two or more substituted or unsubstituted alkenyl groups; or a substituted or unsubstituted alkynyl group, they can act as a crosslinker to promote the efficiency of SEI formation, and as a result, can help form a stronger SEI layer. By forming such a stable SEI layer, it plays a role in extending the life of the electrode or effectively reducing the swelling of the battery caused by electrolyte decomposition at high temperatures. In addition, since the compounds represented by Formula I and Formula II contain a fluorine element, they serve as a fluorine ion source during reduction / oxidation decomposition reactions and play a role in helping to form LiF, a stable inorganic compound contained in the SEI layer.

[0074] According to the present invention, in the above formula I, R a Specifically, C substituted with one or more fluorine atoms 1 -C 6 More specifically, C substituted with one or more fluorine atoms 1 -C 5 The alkyl group may be:

[0075] According to the present invention, in the above formula I, R b Specifically, each independently represents C substituted with one or more fluorine atoms. 1 -C 10 More specifically, each independently may be an alkyl group of the formula:1 -C 6 More specifically, each independently is substituted with one or more fluorine atoms. 1 -C 5 The alkyl group may be:

[0076] According to the present invention, in the formula I, R' is specifically and independently hydrogen; or substituted or unsubstituted C 1 -C 10 More specifically, each independently is hydrogen; or a substituted C 1 -C 6 more specifically, each independently is hydrogen; or substituted C 1 -C 5 In this case, the substituent may specifically be a fluoro group.

[0077] According to the present invention, in the formula I, R″ is specifically an unsubstituted C 2 -C 10 or an unsubstituted C 2 -C 10 and more specifically, an unsubstituted C 2 -C 6 or an unsubstituted C 2 -C 6 and more particularly, unsubstituted C 2 -C 5 or an unsubstituted C 2 -C 5 The alkynyl group may be:

[0078] According to the present invention, the compound represented by the formula I may be one or more compounds selected from the compounds represented by the following formulas Ia to If.

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[0085] Meanwhile, the compound represented by the formula I can be prepared by a reaction of replacing the halogen element of a silane compound containing Si directly bonded to the halogen element with an alcohol, but is not limited thereto, and can be prepared by a known method. For example, as described in Organometallics, 2011, vol. 30. #2, p. 352-355, SiH(OR) 3 The compound may be produced by introducing an alkyne into a silane compound represented by the following formula:

[0086] According to the present invention, in the above formula II, R b Specifically, each independently represents C substituted with one or more fluorine atoms. 1 -C 10 More specifically, each independently may be an alkyl group of the formula: 1 -C 6 More specifically, each independently is substituted with one or more fluorine atoms. 1 -C 5For example, the R b is a C containing a trifluoro group. 1 -C 5 The alkyl group may be:

[0087] According to the present invention, in the formula II, R' is specifically and independently hydrogen; or unsubstituted C 1 -C 10 More specifically, each independently is hydrogen; or an unsubstituted C 1 -C 6 more specifically, each independently is hydrogen; or unsubstituted C 1 -C 5 The alkyl group may be:

[0088] According to the present invention, in the above formula II, R″ is specifically an unsubstituted C 2 -C 10 or an unsubstituted C 2 -C 10 and more specifically, an unsubstituted C 2 -C 6 or an unsubstituted C 2 -C 6 and more particularly, unsubstituted C 2 -C 5 or an unsubstituted C 2 -C 5 The alkynyl group may be:

[0089] According to the present invention, the compound represented by the formula II may be one or more compounds selected from the compounds represented by the following formulae II-a to II-f.

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[0096] According to the present invention, in the above-mentioned chemical formula III, R c Specifically, each independently represents an unsubstituted C 1 -C 10 Alkyl groups of C substituted with one or more fluorine atoms; 1 -C 10 or cyano-substituted C 1 -C 10 The R c More specifically, each independently represents an unsubstituted C 1 -C 6 Alkyl groups of C substituted with one or more fluorine atoms; 1 -C 10 or cyano-substituted C 1 -C 6 The alkyl group may be:

[0097] According to the present invention, in the formula III, R″ is specifically an unsubstituted C 2 -C 10 or an unsubstituted C 2 -C 10and more specifically, an unsubstituted C 2 -C 6 or an unsubstituted C 2 -C 6 and more particularly, unsubstituted C 2 -C 5 or an unsubstituted C 2 -C 5 The alkynyl group may be:

[0098] According to the present invention, the compound represented by the formula III may be one or more compounds selected from the compounds represented by the following formulae III-a to III-o:

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[0114] According to the present invention, in the formula IV, R″ is specifically an unsubstituted C 2 -C 10 or an unsubstituted C 2 -C 10 and more specifically, an unsubstituted C 2 -C 6 or an unsubstituted C 2 -C 6and more particularly, unsubstituted C 2 -C 5 or an unsubstituted C 2 -C 5 The alkynyl group may be:

[0115] According to the present invention, the compound represented by the formula IV may be one or more compounds selected from the compounds represented by the following formulae IV-a to IV-c.

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[0119] According to the present invention, in the formula V, R' is specifically and independently hydrogen; or unsubstituted C 1 -C 10 More specifically, each independently is hydrogen; or an unsubstituted C 1 -C 6 more specifically, each independently is hydrogen; or unsubstituted C 1 -C 5 The alkyl group may be:

[0120] According to the present invention, in the formula V, R″ is specifically an unsubstituted C 2 -C 10 or an unsubstituted C 2 -C 10 and more specifically, an unsubstituted C 2 -C 6 or an unsubstituted C2 -C 6 and more particularly, unsubstituted C 2 -C 5 or an unsubstituted C 2 -C 5 The alkynyl group may be:

[0121] According to the present invention, in the above-mentioned chemical formula V, R d and R e are specifically each independently hydrogen; unsubstituted C 1 -C 10 siloxane groups and / or siloxane groups substituted with silane groups; or unsubstituted siloxane groups, more specifically each independently being hydrogen; unsubstituted C 1 -C 6 alkyl groups; siloxane groups and / or siloxane groups substituted with silane groups; or unsubstituted siloxane groups, more particularly each independently hydrogen; unsubstituted C 1 -C 5 siloxane groups and / or siloxane groups substituted with silane groups; or unsubstituted siloxane groups. d and R e When both of R d and R e may be linked to each other to form a ring consisting of siloxane bonds.

[0122] According to the present invention, the compound represented by formula V may be one or more compounds selected from the compounds represented by formulas Va and Vb below.

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[0125] According to the present invention, the weight ratio (A:B) of the compound (A) represented by the formula I to one or more compounds (B) selected from the compounds represented by the formulas II to V may be 1 to 100:1, specifically 1 to 50:1, 1 to 40:1, 1 to 30:1, 1 to 20:1, 1 to 10:1, more specifically 1 to 9:1, 1 to 8:1, 1 to 7:1, 1 to 6:1, 1 to 5:1, 1 to 4:1, 1 to 3:1, 1 to 2:1. In this case, the compound represented by the formula I is abundant compared to the compounds represented by the formulas II to V acting as a crosslinking agent, and can efficiently form a crosslink, so that an SEI layer having strong mechanical rigidity is formed, and battery stability can be improved.

[0126] According to the present invention, the non-aqueous electrolyte may include the compound represented by Formula I in an amount of 0.01 to 10 parts by weight, specifically 0.01 to 5 parts by weight, 0.01 to 1 part by weight, or 0.1 to 1 part by weight, based on 100 parts by weight of the non-aqueous electrolyte. The non-aqueous electrolyte may also include one or more compounds selected from the compounds represented by Formulas II to V in an amount of 0.01 to 10 parts by weight, specifically 0.01 to 5 parts by weight, 0.01 to 2.5 parts by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte. In this case, when the nonaqueous electrolyte is applied to a secondary battery, the SEI layer derived from the compound represented by Chemical Formula I and one or more compounds selected from the compounds represented by Chemical Formula II and Chemical Formula V has an appropriate thickness that allows lithium ions to move smoothly and has strong mechanical rigidity, thereby improving stability, preventing an increase in internal resistance of the secondary battery, and preventing a decrease in battery capacity.

[0127] (2) Organic Solvent The organic solvent is a non-aqueous solvent commonly used in lithium secondary batteries, and is not limited as long as it can minimize decomposition due to an oxidation reaction during the charge / discharge process of the secondary battery and can exhibit desired properties together with the additives.

[0128] The organic solvent may be, for example, a linear or cyclic carbonate, a linear or cyclic ester, an ether, a glyme, a nitrile (acetonitrile, SN, etc.), etc., but is not limited thereto. As the organic solvent, typically, a carbonate-based electrolyte solvent containing a carbonate compound that is a cyclic carbonate, a linear carbonate, or a mixture thereof can be used.

[0129] On the other hand, specific examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, and fluoroethylene carbonate (FEC), but are not limited thereto.

[0130] Specific examples of the linear carbonate compound include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate.

[0131] Specific examples of the linear ester compound include, but are not limited to, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0132] Specific examples of the cyclic ester compound include, but are not limited to, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0133] Specific examples of the ether solvent include, but are not limited to, dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL).

[0134] The glyme-based solvent has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents and is less reactive with metals. Examples of the glyme-based solvent include, but are not limited to, dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0135] Specific examples of the nitrile solvent include, but are not limited to, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile.

[0136] On the other hand, the cyclic carbonate organic solvents, ethylene carbonate and propylene carbonate, are high viscosity organic solvents, have high dielectric constants, and can easily dissociate the lithium salt in the electrolyte, so they can be used preferably.When such cyclic carbonates are mixed with linear carbonates with low viscosity and low dielectric constants, such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, in an appropriate ratio, they can produce an electrolyte with high electrical conductivity, so they can be used more preferably.In this case, the cyclic carbonates and linear carbonates can be mixed in a volume ratio of 2:8 to 4:6.

[0137] (3) Lithium salt The lithium salt is used as an electrolyte salt in a lithium secondary battery and is used as a medium for transferring ions. Generally, the lithium salt is LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiClO 4 , LiN(C 2 F 5 SO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , C.F. 3 SO 3 Li, LiC(CF 3 SO 2 ) 3 , LiC 4 BO 8 , LiTFSI, LiFSI, and LiClO 4 and preferably LiPF 6 The lithium salts may include, but are not limited to, the following: On the other hand, the lithium salts may be used alone or in combination of two or more as required.

[0138] According to the present invention, the lithium salt may be contained in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, and preferably at a concentration of 0.5 M to 4 M. When the concentration of the lithium salt is within the above range, the concentration of lithium ions in the electrolyte is appropriate, which facilitates charging and discharging of the battery, and the viscosity of the electrolyte is appropriate, which provides excellent wetting in the battery, thereby improving the performance of the battery.

[0139] (4) Other electrolyte additives The non-aqueous electrolyte may further contain other electrolyte additives.

[0140] The other electrolyte additives are known electrolyte additives that can be further added to the non-aqueous electrolyte of the present invention, and examples of such additives include vinylene carbonate, vinyl ethylene carbonate, catechol carbonate, α-bromo-γ-butyrolactone, methyl chloroformate, succinimide, N-benzyloxycarbonyloxysuccinimide, N-hydroxysuccinimide, N-chlorosuccinimide, and methyl cinnamate. cinnamate, 1,3,5-tricyanobenzene, tetracyanoquinodimethane, pyrocarbonate, cyclohexylbenzene, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, fluoroethylene carbonate, LiPO 2 F 2, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), TMSPi (Tris(trimethylsilyl)Phosphite), 12-crown-4, 15-crown-5, 18-crown-6, aza-ethers, boranes, borates, boronates, ferrocene, and their derivatives, LiBF 4 etc.

[0141] The other electrolyte additives may be included in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 7.0 parts by weight, and more preferably 0.05 to 5.0 parts by weight, based on 100 parts by weight of the non-aqueous electrolyte.

[0142] Lithium secondary battery The present invention provides a lithium secondary battery containing the nonaqueous electrolyte.

[0143] Specifically, the lithium secondary battery includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and the nonaqueous electrolyte according to the present invention.

[0144] In this regard, the lithium secondary battery of the present invention may be manufactured by a conventional method known in the art, for example, by forming an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, inserting the electrode assembly into a battery case, and injecting the non-aqueous electrolyte according to the present invention into the battery case.

[0145] (1) Positive electrode The positive electrode may be prepared by coating a positive electrode slurry, which includes a positive electrode active material, a binder, a conductive material, and a solvent, on a positive electrode current collector.

[0146] The positive current collector is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel may be used. Further, the binding force of the positive electrode active material may be strengthened by forming fine irregularities on the surface, and it can be used in various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabric bodies, etc.

[0147] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium metal oxide is a lithium-manganese-based oxide (e.g., LiMnO 2 , LiMn 2 O 4 etc.), lithium-cobalt-based oxide (e.g., LiCoO 2 etc.), lithium-nickel-based oxide (e.g., LiNiO 2 etc.), lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O 2 (where 0 < Y < 1), LiMn 2-Z Ni Z O 4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O 2 (where 0 < Y1 < 1), etc.), lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O 2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O 4 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Coq Mn r1 )O 2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O 4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or lithium - nickel - cobalt - transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O 2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are atomic fractions of independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, p2 + q2 + r3 + s2 = 1), etc.) etc. may be mentioned, and any one or two or more of these compounds may be included.

[0148] Among them, from the point that the capacity characteristics and stability of the battery can be enhanced, the lithium metal oxide is LiCoO 2 , LiMnO 2 , LiNiO 2 , lithium nickel manganese cobalt oxide (e.g., Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O 2 , Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 , and Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co0.15 Al 0.05 )O 2 In consideration of the remarkable improvement effect by controlling the types and content ratio of the constituent elements forming the lithium composite metal oxide, the lithium composite metal oxide may be Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 , Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 , Li(Ni 0.7 Mn 0.15 Co 0.15 )O 2 , and Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 etc., and any one or a mixture of two or more of these can be used.

[0149] The positive electrode active material may be contained in an amount of 60% to 99% by weight, preferably 70% to 99% by weight, and more preferably 80% to 98% by weight, based on the total weight of solids excluding the solvent in the positive electrode slurry.

[0150] The binder is a component that assists in binding the active material and conductive material and the like to the current collector.

[0151] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene (PE), polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, various copolymers, and the like.

[0152] Generally, the binder may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids excluding the solvent in the positive electrode slurry.

[0153] The conductive material is a component for further improving the conductivity of the positive electrode active material.

[0154] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and examples of the conductive material that can be used include graphite; carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, 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.

[0155] Generally, the conductive material may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids excluding the solvent in the positive electrode slurry.

[0156] The solvent may contain an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a suitable viscosity when the positive electrode active material, and optionally a binder and a conductive material, etc. are contained. For example, the solvent may be contained so that the concentration of the solid content including the positive electrode active material, and optionally a binder and a conductive material, is 50% by weight to 95% by weight, preferably 70% by weight to 95% by weight, and more preferably 70% by weight to 90% by weight.

[0157] (2) Negative electrode The negative electrode can be prepared by coating a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and a solvent, or a graphite electrode made of carbon (C) or a metal itself can be used as the negative electrode.

[0158] For example, when the negative electrode is produced by coating the negative electrode slurry on the negative electrode collector, the negative electrode collector generally has a thickness of 3 to 500 μm. Such a negative electrode collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity, and for example, copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. may be used. In addition, as with the positive electrode collector, the binding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface, and it can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0159] The negative electrode active material may be natural graphite, artificial graphite, carbonaceous material, lithium-containing titanium oxide (LTO), Si, SiO x , Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe; alloys composed of the metals (Me); oxides of the metals (Me) (MeO x ); and a composite of the metal (Me) and carbon. Specifically, the negative electrode active material is silicon (Si), silicon oxide (SiO x ), or a silicon-based negative electrode active material including a silicon alloy, etc., may be used. In this case, a thin and stable SEI layer including a siloxane bond is formed, which can further improve the high-temperature stability and life characteristics of the battery.

[0160] The negative electrode active material may be contained in an amount of 60% to 99% by weight, preferably 70% to 99% by weight, and more preferably 80% to 98% by weight, based on the total weight of solids excluding the solvent in the negative electrode slurry.

[0161] The binder is a component that assists in binding between the conductive material, the active material, and the current collector. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0162] Generally, the binder may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids excluding the solvent in the negative electrode slurry.

[0163] The conductive material is a component for further improving the conductivity of the negative electrode active material. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and has conductivity, and may be, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fiber such as carbon fiber or metal fiber; metal powder such as carbon fluoride, aluminum, nickel powder; conductive whisker such as zinc oxide, potassium titanate; conductive metal oxide such as titanium oxide; conductive material such as polyphenylene derivative.

[0164] The conductive material may be contained in an amount of 1 wt % to 20 wt %, preferably 1 wt % to 15 wt %, and more preferably 1 wt % to 10 wt %, based on the total weight of solids excluding the solvent in the negative electrode slurry.

[0165] The solvent may include water or an organic solvent such as NMP (N-methyl-2-pyrrolidone), and may be used in an amount that provides a suitable viscosity when the negative electrode active material, and optionally a binder and a conductive material, etc. are included. For example, the solvent may be included so that the concentration of the solid content including the negative electrode active material, and optionally a binder and a conductive material, is 50% by weight to 95% by weight, preferably 70% by weight to 90% by weight.

[0166] When a metal is used as the negative electrode, the negative electrode can be manufactured by physically bonding, rolling, or depositing a metal on a metal thin film or the negative electrode current collector. The deposition method can be an electrical deposition or chemical vapor deposition method.

[0167] For example, the metal thin film itself or the metal bonded / rolled / deposited onto the negative electrode current collector may include one metal or an alloy of two metals selected from the group consisting of lithium (Li), nickel (Ni), tin (Sn), copper (Cu), and indium (In).

[0168] (3) Separator The separator may be a conventional porous polymer film, such as a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, or an ethylene / methacrylate copolymer, which may be used alone or in a laminated state, or a conventional porous nonwoven fabric, such as a nonwoven fabric made of a high melting point glass fiber, a polyethylene terephthalate fiber, etc., may be used, but is not limited thereto. In addition, in order to ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymeric substance may be used, and may be selectively used as a single layer or a multilayer structure.

[0169] The external shape of the lithium secondary battery of the present invention is not particularly limited, and may be a cylindrical shape using a can, a square shape, a pouch shape, a coin shape, or the like.

[0170] According to the present invention, there is provided a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same. The battery module and the battery pack include the lithium secondary battery having high capacity, high rate characteristics, and cycle characteristics, and therefore can be used as a power source for medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. EXAMPLES

[0171] The present invention will be described in more detail below with reference to specific examples. However, the following examples are merely illustrative for understanding the present invention and are not intended to limit the scope of the present invention. It is obvious to those skilled in the art that various changes and modifications are possible within the scope of the scope and technical ideas of the present description, and it goes without saying that such changes and modifications belong to the scope of the attached claims.

[0172] Synthesis Example Synthesis Example 1. Preparation of Compound Represented by Formula Ia 3.5 equivalents of 2,2,2-trifluoroethanol were placed in a two-necked round-bottom flask, which was then connected to a dropping funnel and a reflux condenser. The round-bottom flask was placed in an oil bath and heated to 50°C. While flowing nitrogen gas, 1 equivalent of trichlorovinylsilane was slowly dropped through the dropping funnel over 1 hour. After the dropwise addition was completed, the reactant was refluxed at 70°C while flowing nitrogen gas, reacted overnight, cooled to room temperature, and the pH was checked. If the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt generated in this process was filtered. The remaining reactants and by-products were removed by reducing the pressure at room temperature, and then the compound represented by formula Ia was obtained by distillation under reduced pressure at 60°C.

[0173] Compounds of formula Ia 1 The H-NMR data is as follows: 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 6.34(1H, dd), 6.18(1H, dd), 5.85(1H, dd), 4.12(6H, q)

[0174] Synthesis Example 2. Preparation of compound represented by formula II-a 2.5 equivalents of 2,2,2-trifluoroethanol were placed in a two-necked round-bottom flask, which was then connected to a dropping funnel and a reflux condenser. The round-bottom flask was placed in an oil bath and heated to 50°C. While flowing nitrogen gas, 1 equivalent of dichlorodivinylsilane was slowly dropped through the dropping funnel over 1 hour. After the dropwise addition was completed, the reactant was refluxed at 70°C while flowing nitrogen gas, reacted overnight, cooled to room temperature, and the pH was checked. If the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt generated in this process was filtered. The remaining reactants and by-products were removed by reducing the pressure at room temperature, and then the compound represented by chemical formula II-a was obtained by distillation under reduced pressure at 55°C.

[0175] Compounds represented by formula II-a 1 The H-NMR data is as follows: 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 6.32(2H, dd), 6.14(2H, dd), 5.84(2H, dd), 4.23(4H, q)

[0176] Synthesis Example 3. Preparation of compound represented by formula III-b Under a nitrogen atmosphere and ice bath, dichlorodimethylsilane (1 equivalent) was slowly added dropwise to a Schlenk round-bottom flask containing allylmagnesium bromide (2.2 equivalents, 1M in Ether) over a period of 1 hour. The reaction was then allowed to proceed overnight at room temperature. NH 4 The reaction was terminated by adding 5 equivalents of a saturated aqueous solution of Cl dropwise. The aqueous solution was removed by layer separation, and the resulting organic layer was washed with CaCl 2 The mixture was dried at 40°C, and the precipitate was removed by filtration. The remaining reactants and by-products were removed by reducing the pressure at room temperature, and then the compound represented by formula III-b was obtained by distillation at 80°C under reduced pressure.

[0177] Compounds represented by formula III-b 1 The H-NMR data is as follows: 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 5.77(2H, m), 4.85(4H, m), 1.53(4H, d), 0.00(6H, s)

[0178] Synthesis Example 4. Preparation of compound represented by formula III-j In a nitrogen atmosphere and ice bath, 3-(trichlorosilyl)propanenitrile (1 equivalent) was slowly added dropwise to a Schlenk round-bottom flask containing vinylmagnesium bromide (3.3 equivalents, 1M in Ether) over a period of 1 hour. The reaction was then carried out overnight at room temperature. NH 4 The reaction was terminated by adding 7 equivalents of a saturated aqueous solution of Cl dropwise. The aqueous solution was removed by layer separation, and the resulting organic layer was treated with CaCl 2 The mixture was dried at 40°C, and the precipitate was removed by filtration. The remaining reactants and by-products were removed by reducing the pressure at room temperature, and then the compound represented by formula III-j was obtained by distillation at 120°C under reduced pressure.

[0179] Compounds represented by formula III-j 1 The H-NMR data is as follows: 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 6.13(6H, m), 5.82(3H, m), 2.39(2H, t), 1.13(2H, t)

[0180] Synthesis Example 5. Preparation of Compound Represented by Formula III-m Trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (1 equivalent) was slowly added dropwise to a Schlenk round-bottom flask containing vinylmagnesium bromide (3.3 equivalents, 1M in Ether) under a nitrogen atmosphere and an ice bath over a period of 1 hour. The reaction was then allowed to proceed overnight at room temperature. NH 4The reaction was terminated by adding 7 equivalents of a saturated aqueous solution of Cl dropwise. The aqueous solution was removed by layer separation, and the resulting organic layer was treated with CaCl 2 The mixture was dried at 40°C, and the precipitate was removed by filtration. The remaining reactants and by-products were removed by reducing the pressure at room temperature, and then the compound represented by formula III-m was obtained by distillation at 110°C under reduced pressure.

[0181] Compounds represented by formula III-m 1 The H-NMR data is as follows: 1 H-NMR (400 MHz, CDCl 3 ) δ(ppm): 6.14(6H, m), 5.83(3H, m), 2.07(2H, m), 0.97(2H, m)

[0182] Examples and Comparative Examples Example 1 (Production of non-aqueous electrolyte) 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 0.67 g of the compound represented by formula Ia and 0.33 g of the compound represented by formula II-a to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved.

[0183] (Secondary battery manufacturing) Cathode active material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ), a conductive material (carbon black), and a binder (polyvinylidene fluoride) were added to N-methyl-2-pyrrolidone (NMP) in a weight ratio of 97.5:1:1.5 to prepare a slurry for the positive electrode (solid matter 60% by weight). The slurry for the positive electrode was applied to one side of a positive electrode current collector (aluminum thin film) having a thickness of 15 μm, and dried and roll pressed to prepare a positive electrode.

[0184] A negative electrode slurry (solid content 50 wt%) was prepared by adding a negative electrode active material (graphite:silicon oxide = 92:8 weight ratio), a conductive material (carbon black), styrene-butadiene rubber, and carboxymethyl cellulose to distilled water in a weight ratio of 95:1.5:1.5:2. The negative electrode slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 15 μm, and dried and roll pressed to prepare a negative electrode.

[0185] In a dry room, a porous polypropylene separator was interposed between the prepared positive electrode and negative electrode to prepare an electrode assembly, which was then placed in a battery case, the non-aqueous electrolyte was injected, and the battery case was sealed to prepare a pouch-type lithium secondary battery (battery capacity 6.24 mAh).

[0186] Example 2 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of the compound represented by formula II-a to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0187] Example 3 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of the compound represented by formula III-b to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0188] Example 4 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF4 To 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 by volume ratio) in which 4 was dissolved, 0.5 g of the compound represented by the chemical formula I-a and 0.5 g of the compound represented by the chemical formula III-j were added to produce a non-aqueous electrolyte. A lithium secondary battery was produced in the same manner as in Example 1 except that the non-aqueous electrolyte thus produced was used.

[0189] Example 5 1.0M LiPF 6 To 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 by volume ratio) in which 1.0M LiPF, 0.5 wt% VC, and 0.2 wt% LiBF 6 were dissolved, 0.5 g of the compound represented by the chemical formula I-a and 0.5 g of the compound represented by the chemical formula III-m were added to produce a non-aqueous electrolyte. A lithium secondary battery was produced in the same manner as in Example 1 except that the non-aqueous electrolyte thus produced was used. 4 4

[0190] Example 6 1.0M LiPF 6 To 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 by volume ratio) in which 1.0M LiPF, 0.5 wt% VC, and 0.2 wt% LiBF 6 were dissolved, 0.5 g of the compound represented by the chemical formula I-a and 0.5 g of the compound represented by the chemical formula IV-a, tetravinylsilane (Sigma-Aldrich), were added to produce a non-aqueous electrolyte. A lithium secondary battery was produced in the same manner as in Example 1 except that the non-aqueous electrolyte thus produced was used. 4 4

[0191] Example 7 1.0M LiPF 6 To 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 by volume ratio) in which 1.0M LiPF, 0.5 wt% VC, and 0.2 wt% LiBF 6 were dissolved, 0.5 g of the compound represented by the chemical formula I-a and 0.5 g of the compound represented by the chemical formula IV-a, tetravinylsilane (Sigma-Aldrich), were added to produce a non-aqueous electrolyte. A lithium secondary battery was produced in the same manner as in Example 1 except that the non-aqueous electrolyte thus produced was used. 4A non-aqueous electrolyte solution was prepared by adding 0.5 g of the compound represented by formula Ia and 0.5 g of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Tokyo Chemical Industry Co., Ltd.) represented by formula Vb to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0192] Comparative Example 1 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) in which the above was dissolved was used as a non-aqueous electrolyte.

[0193] Comparative Example 2 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0194] Comparative Example 3 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 1 g of tetraethoxysilane (TEOS) (Sigma-Aldrich) to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0195] Comparative Example 4 1.0M LiPF 6 , 0.5wt% VC, 0.2wt% LiBF 4 A non-aqueous electrolyte solution was prepared by adding 1 g of the compound represented by formula Ia to 99 g of an organic solution (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3: 7 volume ratio) in which the above was dissolved. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte solution prepared in this manner was used.

[0196] [Table 1]

[0197] Experimental Example Experimental example 1: Evaluation of high temperature (60℃) storage characteristics The volume change rate and resistance increase rate after high-temperature storage were confirmed by the following methods.

[0198] 1) Volume change rate after high temperature storage (%) The secondary batteries manufactured in Examples 1 to 7 and Comparative Examples 1 to 4 were activated at a constant current (CC) of 0.1C. Then, using a PESCO5-0.5 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5V, 500mA) at 25°C, the batteries were charged at a constant current of 0.3C up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, and then a 0.05C current cut was performed, followed by discharging at 0.33C up to 2.5V under CC conditions. The above charge / discharge cycle was counted as one cycle, and two cycles were performed. Next, the batteries were fully charged at a constant current-constant voltage of 0.33C / 4.2V, and discharged at 2.5C for 10 seconds at SOC50%, and the initial resistance was calculated from the difference between the voltage before and after discharging for 10 seconds. Next, the batteries were discharged at a constant current of 0.33C up to 2.5V. Then, the batteries were degassed, and the initially charged and discharged lithium secondary batteries were placed in a bowl filled with water at room temperature using a Two-pls TWD-150DM device, and the initial volume was measured.The lithium secondary batteries were then fully charged at a constant current-constant voltage of 0.33C / 4.2V, and stored at 60°C for 4 weeks (SOC100%), and then the lithium secondary batteries were placed in a bowl filled with water at room temperature using a Two-pls TWD-150DM device, and the volume after high-temperature storage was measured.

[0199] The initial volume and the volume after high-temperature storage measured as described above were substituted into the following formula (1) to evaluate the volume change rate, and the results are shown in Table 2 below.

[0200] Formula (1): Volume change rate after high-temperature storage (%) = {(volume after high-temperature storage - initial volume) / initial volume} x 100

[0201] 2) Resistance increase rate after high temperature storage (%) The secondary batteries manufactured in Examples 1 to 7 and Comparative Examples 1 to 4 were activated at a constant current (CC) of 0.1C. Then, using a PESCO5-0.5 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5V, 500mA) at 25°C, the batteries were charged at a constant current of 0.3C up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, and then a 0.05C current cut was performed, followed by discharging at 0.33C up to 2.5V under CC conditions. The above charge / discharge cycle was counted as one cycle, and two cycles were performed. Next, the batteries were fully charged at a constant current-constant voltage of 0.33C / 4.2V, and discharged at 2.5C for 10 seconds at SOC50%, and the initial resistance was calculated from the difference between the voltage before and after discharging for 10 seconds. Next, the batteries were discharged at a constant current of 0.33C up to 2.5V. Then, the batteries were degassed, charged at 4.2 V, and stored at 60° C. for 4 weeks (SOC 100%). After that, the batteries were discharged at 2.5 C for 10 seconds at SOC 50%, and the resistance after high-temperature storage was measured.

[0202] The initial resistance value and the resistance value after high-temperature storage measured as described above were substituted into the following formula (2) to evaluate the resistance increase rate, and the results are shown in Table 2 below.

[0203] Equation (2): Resistance increase rate after high-temperature storage (%) = {(resistance value after high-temperature storage - initial resistance value) / initial resistance value} x 100

[0204] [Table 2]

[0205] Experimental example 2: Cycle characteristics evaluation The secondary batteries manufactured in Examples 1 to 7 and Comparative Examples 1 to 4 were activated at a constant current (CC) of 0.1C. Then, using a PESCO5-0.5 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5V, 500mA) at 25°C, the batteries were charged at a constant current of 0.3C up to 4.2V under constant current-constant voltage (CC-CV) charging conditions, and then a 0.05C current cut was performed, followed by discharging at 0.33C up to 2.5V under CC conditions. The above charge / discharge cycle was counted as one cycle, and two cycles were performed. Next, the batteries were fully charged at a constant current-constant voltage of 0.33C / 4.2V, and discharged at 2.5C for 10 seconds at SOC50%, and the initial resistance was calculated from the difference between the voltage before and after discharging for 10 seconds. Next, the batteries were discharged at a constant current of 0.33C up to 2.5V.

[0206] Next, the batteries were degassed, and each battery was charged at a constant current of 0.33C under a voltage driving range of 2.5V to 4.5V at 45°C until the battery voltage reached 4.2V. The battery was then charged at a constant voltage of 4.2V, and the charging was terminated when the charging current reached 0.05C. Next, the battery was left for 20 minutes, and then discharged at a constant current of 0.33C until the battery voltage reached 2.5V. The above charge and discharge were counted as one cycle, and 100 cycles of charge and discharge were performed. At this time, the capacity after one cycle and the capacity after 100 cycles were measured using a PESCO5-0.5 charger and discharger (manufacturer: PNE Solution Co., Ltd., 5V, 500mA), and the capacity was substituted into the following formula (3) to evaluate the capacity retention rate. The results are shown in Table 3 below.

[0207] Equation (3): Capacity retention rate after 100 cycles (%) = {(Capacity after 100 cycles - Capacity after 1 cycle) / Capacity after 1 cycle} x 100

[0208] On the other hand, after 100 cycles, the battery was discharged at 2.5 C for 10 seconds at SOC 50%, and the resistance after 100 cycles was calculated from the difference in voltage before and after the 10 seconds of discharge.

[0209] The initial resistance value and the resistance value after 100 cycles measured as described above were substituted into the following formula (4) to evaluate the resistance increase rate. The results are shown in Table 3 below.

[0210] Equation (4): Resistance increase rate after 100 cycles (%) = {(resistance value after 100 cycles - initial resistance value) / initial resistance value} x 100

[0211] [Table 3]

[0212] Referring to Table 2, it can be seen that the secondary batteries manufactured in Examples 1 to 7 have significantly lower volume change rates and resistance increase rates even during high-temperature storage compared to the secondary batteries manufactured in Comparative Examples 1 to 4. Also, referring to Table 3, it can be seen that the secondary batteries manufactured in Examples 1 to 7 have significantly better life characteristics compared to the secondary batteries manufactured in Comparative Examples 1 to 4. This is because when a compound represented by Chemical Formula I and one or more compounds selected from the group consisting of compounds represented by Chemical Formulas II to V are included in a non-aqueous electrolyte as additives, polysiloxane and / or polysilylene are formed between the additives, resulting in the formation of an SEI layer with high structural flexibility and stability. In particular, the secondary batteries manufactured in Examples 1 to 7 contain a silicon-based negative electrode active material, and can form a stronger SEI layer having a covalent bond-based polysiloxane network on the surface of the negative electrode, thereby doubling the strong durability of the SEI layer. As a result, it is possible to confirm a more excellent effect of improving the capacity retention rate and the resistance increase rate.

[0213] Therefore, it can be seen that, when the compound represented by chemical formula I and one or more compounds selected from the compounds represented by chemical formulas II to V are contained as additives in a non-aqueous electrolyte solution as in the present invention, a strong SEI layer having low resistance is formed, and a lithium secondary battery having excellent high-temperature stability and life characteristics can be provided.

Claims

1. An organic solvent; A lithium salt; A compound represented by the following formula I: and one or more compounds selected from the group consisting of compounds represented by the following chemical formulas II to V: 【Chemistry 1】 (In the above Chemical Formulas I to V, R ａ is C substituted with one or more fluorine atoms. １ -C １０ is an alkyl group of the formula R ｂ each independently represents a C which is substituted or not substituted with one or more fluorine atoms; １ -C １０ is an alkyl group of the formula R ｃ are each independently substituted or unsubstituted C １ -C １０ is an alkyl group of the formula R′ is independently hydrogen; １ -C １０ or a substituted or unsubstituted C １ -C １０ is a heteroalkyl group of the formula R″ is a substituted or unsubstituted C ２ -C １０ or a substituted or unsubstituted C ２ -C １０ is an alkynyl group of the formula R ｄ and R ｅ are each independently hydrogen; １ -C １０ an alkyl group of the formula: １ -C １０ or a substituted or unsubstituted siloxane group, R ｄ and R ｅ When both are siloxane groups, R ｄ and R ｅ may be linked to each other to form a ring consisting of a siloxane bond, n is 2 or 3.

2. The non-aqueous electrolyte according to claim 1, wherein the compound represented by formula I is one or more compounds selected from the compounds represented by formulas I-a to If: 【Chemistry 2A】 【Chemistry 2B】

3. The non-aqueous electrolyte according to claim 1, wherein the compound represented by the chemical formula II is one or more compounds selected from the compounds represented by the following chemical formulas II-a to II-f. 【Chemistry 3A】 【Chemistry 3B】

4. The non-aqueous electrolyte according to claim 1, wherein the compound represented by the formula III is one or more compounds selected from the compounds represented by the following formulas III-a to III-o: 【Chemistry 4A】 【Chemistry 4B】 【Chemistry 4C】 【Chemistry 4D】

5. The non-aqueous electrolyte according to claim 1, wherein the compound represented by formula IV is one or more compounds selected from the compounds represented by formulas IV-a to IV-c below. 【Chemistry 5】

6. The nonaqueous electrolyte according to claim 1, wherein the compound represented by the chemical formula V is one or more compounds selected from the compounds represented by the following chemical formulas Va and Vb. 【Chemistry 6】

7. The nonaqueous electrolyte according to claim 1, wherein the weight ratio of the compound represented by the chemical formula I to one or more compounds selected from the compounds represented by the chemical formulas II to V is 1 to 100:

1.

8. 2. The non-aqueous electrolyte according to claim 1, comprising the compound represented by Formula I in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte.

9. The non-aqueous electrolyte according to claim 1, comprising at least one compound selected from the group consisting of compounds represented by Formulas II to V in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the non-aqueous electrolyte.

10. a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; a separator interposed between the positive electrode and the negative electrode; A lithium secondary battery comprising the nonaqueous electrolyte solution according to claim 1 .

11. The lithium secondary battery according to claim 10 , wherein the negative electrode active material is a silicon-based negative electrode active material.

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