Non-aqueous electrolyte and lithium secondary battery containing the 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 priority under Korean Patent Application No. 10-2022-0094116 dated 28 July 2022, and all content disclosed in the said Korean Patent Application is incorporated herein by reference.

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

[0003] In recent years, the application areas of lithium-ion batteries have rapidly expanded beyond power supply for electronic devices such as electrical, electronic, telecommunications, and computers to include power storage and supply for large-area equipment such as automobiles and power storage devices. Consequently, there is an increasing demand for high-capacity, high-output, and highly stable secondary batteries.

[0004] Lithium-ion secondary batteries are typically manufactured by applying a mixture of a positive electrode active material, such as a lithium-containing transition metal oxide, or a carbon-based or silicon-based negative electrode active material capable of intercalating and deintercalating lithium ions, along with a binder and conductive material, to the positive and negative electrode current collectors, respectively. These are then stacked on both sides of a separator to form electrode current collectors of a predetermined shape, and finally, these electrode current collectors and a non-aqueous electrolyte are inserted into the battery case. To ensure the performance of the battery, formation and aging processes are almost always necessary.

[0005] The formation process is a step in which the secondary battery is activated by repeatedly charging and discharging after the battery is assembled. During charging, 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 produce compounds such as Li2CO3, Li2O, and LiOH, and these compounds form a solid electrolyte interface (SEI) layer on the electrode surface. The formation of the SEI layer is an important factor because it closely affects the lifespan and capacity maintenance.

[0006] In recent years, high capacity, high power output, and long lifespan characteristics have become particularly important for lithium-ion secondary batteries used in automobiles. To achieve high capacity, on the positive electrode side, a positive electrode active material with high energy density but low stability is used, requiring the formation of an active material-electrolyte interface that protects the surface of the positive electrode active material and stabilizes it. On the negative electrode side, problems such as the decomposition of surface species in the electrolyte and the occurrence of side reactions have been reported, requiring the formation of a strong and low-resistance SEI layer. Furthermore, during storage at high temperatures, the SEI layer may gradually disintegrate, potentially causing problems such as electrode exposure. Therefore, attempts have been made to develop additives in the electrolyte that help in the formation of an SEI interface that can suppress side reactions during high-temperature storage.

[0007] As described above, as high-temperature operation and long-life characteristics become important in lithium secondary batteries, a problem arises in which electrolyte decomposition reactions due to oxidation-reduction reactions occurring at the interface between the electrolyte and electrodes accumulate during repeated cycles, and the resulting increased resistance degrades the lifespan characteristics. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention aims to solve the above-mentioned problems and provides a non-aqueous electrolyte that is stable even at high temperatures and can improve the high-temperature stability and lifespan characteristics of lithium secondary batteries by forming an electrode-electrolyte interface with low resistance, and a lithium secondary battery containing the same. [Means for solving the problem]

[0009] To solve the above problems, the present invention provides a non-aqueous electrolyte and a lithium secondary battery.

[0010] (1) The present invention provides a non-aqueous electrolyte comprising an organic solvent, a lithium salt, a compound represented by the following chemical formula I, and one or more compounds selected from 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 aforementioned chemical formulas I to V, R a This is a C1-C substituted with one or more fluorine elements. 10 It is an alkyl group, R bis, independently of each other, a C1-C alkyl group which is substituted or unsubstituted with one or more fluorine elements 10 and R c is, independently of each other, a C1-C alkyl group which is substituted or unsubstituted 10 and R’ is, independently of each other, hydrogen; a C1-C alkyl group which is substituted or unsubstituted; or a C1-C heteroalkyl group which is substituted or unsubstituted 10 and 10 and [[ID=十六]]R’’ is an alkenyl group of C2-C which is substituted or unsubstituted; or an alkynyl group of C2-C which is substituted or unsubstituted 10 and 10 and R d and R<000001'2>are, independently of each other, hydrogen; a C1-C alkyl group which is substituted or unsubstituted; a C1-C heteroalkyl group which is substituted or unsubstituted; or a siloxane group which is substituted or unsubstituted 10 and 10 and R d and R e If both are siloxane groups, R d and R / e may be connected to each other to form a ring consisting of siloxane bonds n is 2 or 3

[0017] (2) The present invention provides the non-aqueous electrolyte according to (1) above, wherein the compound represented by the chemical formula I is one or more compounds selected from the compounds of the following chemical formulas I-a to I-f

[0018] [[ID=SI]]

Chemical formula

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Chemical formula

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[0024] (3) The present invention provides a non-aqueous electrolyte according to (1) or (2) above, wherein the compound represented by chemical formula II is one or more compounds selected from the compounds of chemical formulas II-a to II-f below.

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[0031] (4) The present invention provides a non-aqueous electrolyte 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 of chemical formulas III-a to III-o below.

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[0047] (5) The present invention provides a non-aqueous electrolyte 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 of chemical formulas IV-a to IV-c below.

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

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

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

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

[0057] (10) The present invention provides a lithium secondary battery comprising 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 according to any one of (1) to (9) above.

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

[0059] As in the present invention, when a silane-based compound represented by chemical formula I and one or more compounds selected from those represented by chemical formulas II to V are both included as additives in a non-aqueous electrolyte, a thin and stable SEI layer is formed, providing a lithium secondary battery with excellent high-temperature stability and lifespan characteristics. [Modes for carrying out the invention]

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

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

[0062] The terms used in this invention are used solely to describe specific embodiments and are not intended to limit the invention. A singular expression includes plural expressions unless the context clearly indicates otherwise. In this invention, terms such as “includes” or “having” are intended to specify the presence of features, figures, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0063] non-aqueous electrolyte The present invention provides a non-aqueous electrolyte comprising an organic solvent, a lithium salt, a compound represented by the following chemical formula I, and one or more compounds selected from 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 aforementioned chemical formulas I to V, R a This is a C1-C substituted with one or more fluorine elements. 10 It is an alkyl group, R b Each of these is independently either substituted with one or more fluorine elements or unsubstituted with C1-C 10 It is an alkyl group, R c These are, independently, C1-C which are either substituted or not substituted. 10 It is an alkyl group, R' independently consists of hydrogen; substituted or unsubstituted C1-C 10 alkyl groups; or substituted or unsubstituted C1-C 10 It is a heteroalkyl group, R'' is either substituted or unsubstituted C2-C 10 alkenyl group; or substituted or unsubstituted C2-C 10 It is an alkynyl group, R d and Re These are, independently, hydrogen; substituted or unsubstituted C1-C 10 alkyl group; substituted or unsubstituted C1-C 10 A heteroalkyl group; or a substituted or unsubstituted siloxane group, R d and R e If both are siloxane groups, R d and R e They may be linked to each other to form a ring consisting of siloxane bonds. n is either 2 or 3.

[0070] In the present invention, in the case of substituted alkyl groups; substituted heteroalkyl groups; substituted alkenyl groups; substituted alkynyl groups; or substituted siloxane groups, the substituents are deuterium (-D), hydroxyl group (-OH), amino group (-NR2), halogen group (-X), thiol group (-SR), cyano group (-CN), carbonyl group (-C(=O)-H, -C(=O)-R, -C(=O)-OH, -C(=O)-NR2, -C(=O)-OR, -C(=O)-X), carbamate group (-OC(=O)-NR2, -NR-C(=O)OR), urea group (-N(R)-C(=O)-NR2), 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)R2), phosphonate (-PO3R2), phosphonit (-P(OR)2), boronic acid (Boronic The substituents may be an acid (-B(OR)2), borate (-OB(OR)2), borane (-BR2), siloxane group (-Si-O-Si-R), silane group (-SiR4), or a linear or branched C1-C6 alkoxy group. In this case, in the substituents, X is a halogen group, and R is independently a C1-C6 group. 10 alkyl group; C2-C 10 alkenyl group of; or C2-C 10 It may be an alkynyl group.

[0071] (1) One or more compounds selected from those represented by chemical formula I and those represented by chemical formulas II to V. The non-aqueous electrolyte according to the present invention includes, as additives, a compound represented by chemical formula I, which is a silane compound, and one or more compounds selected from those represented by chemical formulas II to V. In other words, the non-aqueous electrolyte according to the present invention may contain both the compound represented by chemical formula I and chemical formula II, both the compound represented by chemical formula I and chemical formula III, both the compound represented by chemical formula I and chemical formula IV, both the compound represented by chemical formula I and chemical formula V, both the compound represented by chemical formula I, chemical formula II, and chemical formula III, both the compound represented by chemical formula I, chemical formula II, and chemical formula IV, both the compound represented by chemical formula I, chemical formula II, and chemical formula V, both the compound represented by chemical formula I, chemical formula III, and chemical formula IV, both the compound represented by chemical formula I, chemical formula III, and chemical formula V, both the compound represented by chemical formulas I to IV, both the compound represented by chemical formula I, chemical formula II, chemical formula III, and chemical formula V, both the compound represented by chemical formula I, chemical formula III, chemical formula IV, and chemical formula V.

[0072] 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 both contained in a non-aqueous electrolyte, a thin and stable SEI layer is formed, providing a lithium secondary battery with excellent high-temperature stability and lifespan characteristics. 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, further improving the high-temperature stability and lifespan characteristics of the battery.

[0073] The compound represented by chemical formula I can form a SEI layer with higher mechanical rigidity against volume changes by forming covalent bonds ([electrode]-O-Si-O-) with hydroxyl groups (-OH) on the surface of the negative electrode material or positive electrode material. In particular, when silicon-based negative electrode materials are used, the formation of a siloxane network can protect the silicon-based negative electrode, which undergoes significant volume expansion during charging and discharging. Furthermore, since the compound represented by chemical formula I has substituted or unsubstituted alkenyl groups; or substituted or unsubstituted alkynyl groups, it can form a polymer-type SEI layer by forming CC bonds through reduction / oxidation decomposition reactions. In this case, the compounds represented by chemical formulas II to V have two or more substituted or unsubstituted alkenyl groups; or substituted or unsubstituted alkynyl groups, and can act as crosslinkers to promote SEI formation efficiency, thereby helping to form a stronger SEI layer. By forming such a stable SEI layer, the lifespan of the electrode is extended, or the swelling of the battery caused by electrolyte decomposition at high temperatures is effectively reduced. Furthermore, the compounds represented by chemical formulas I and II contain fluorine, and therefore act as a source of fluorine ions during reduction / oxidation decomposition reactions, playing a role in the formation of LiF, a stable inorganic compound contained in the SEI layer.

[0074] According to the present invention, in the above chemical formula I, R a Specifically, this may be a C1-C6 alkyl group substituted with one or more fluorine elements, or more specifically, a C1-C5 alkyl group substituted with one or more fluorine elements.

[0075] According to the present invention, in the above chemical formula I, R b Specifically, each of these is a C1-C molecule independently substituted with one or more fluorine elements. 10 The alkyl group may be, more specifically, a C1-C6 alkyl group independently substituted with one or more fluorine elements, or more specifically, a C1-C5 alkyl group independently substituted with one or more fluorine elements.

[0076] According to the present invention, in the chemical formula I, R' is specifically and independently hydrogen; or substituted or unsubstituted C1-C 10 The substituents may be alkyl groups, more specifically, each independently of hydrogen; or a substituted C1-C6 alkyl group, and more specifically, each independently of hydrogen; or a substituted C1-C5 alkyl group. In this case, the substituents may specifically be fluoro groups.

[0077] According to the present invention, in the chemical formula I, R'' specifically represents an unsubstituted C2-C 10 alkenyl group; or unsubstituted C2-C 10 The alkynyl group may be, more specifically, an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more specifically, an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

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

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[0085] On the other hand, the compound represented by chemical formula I can be produced by a reaction in which the halogen element of a silane compound containing Si directly bonded to a halogen element is replaced with an alcohol, but is not limited to this, and can be produced by known methods. For example, as described in Organometallics, 2011, vol.30,#2, pp.352-355, it may be produced by introducing an alkyne into a silane compound represented by SiH(OR)3 under a transition metal catalyst.

[0086] According to the present invention, in the above chemical formula II, R b Specifically, each of these is a C1-C molecule independently substituted with one or more fluorine elements. 10 R may be an alkyl group, more specifically, each independently a C1-C6 alkyl group substituted with one or more fluorine elements, and more specifically, each independently a C1-C5 alkyl group substituted with one or more fluorine elements. For example, the R b This may be a C1-C5 alkyl group containing a trifluoro group.

[0087] According to the present invention, in the chemical formula II, R' is specifically and independently hydrogen; or unsubstituted C1-C 10 The alkyl groups may be, more specifically, each independently of hydrogen; or an unsubstituted C1-C6 alkyl group, and more specifically, each independently of hydrogen; or an unsubstituted C1-C5 alkyl group.

[0088] According to the present invention, in the chemical formula II, R'' specifically represents an unsubstituted C2-C 10alkenyl group; or unsubstituted C2-C 10 The alkynyl group may be, more specifically, an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more specifically, an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

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

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[0096] According to the present invention, in the above chemical formula III, R c Specifically, each is independently of the unsubstituted C1-C 10 Alkyl alkyl groups; C1-C substituted with one or more fluorine elements 10Alkyl groups of; or C1-C substituted with cyano groups 10 The R may be an alkyl group. c More specifically, each is independently: an unsubstituted C1-C6 alkyl group; a C1-C6 alkyl group substituted with one or more fluorine elements. 10 The alkyl group may be a C1-C6 alkyl group substituted with a cyano group.

[0097] According to the present invention, in the above chemical formula III, R'' is specifically an unsubstituted C2-C 10 alkenyl group; or unsubstituted C2-C 10 The alkynyl group may be, more specifically, an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more specifically, an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0098] According to the present invention, the compound represented by chemical formula III may be one or more compounds selected from the compounds of chemical formulas III-a to III-o below.

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[0114] According to the present invention, in the chemical formula IV, R'' specifically represents an unsubstituted C2-C 10 alkenyl group; or unsubstituted C2-C 10 The alkynyl group may be, more specifically, an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more specifically, an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

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

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[0119] According to the present invention, in the chemical formula V, R' is specifically and independently hydrogen; or unsubstituted C1-C 10 The alkyl groups may be, more specifically, each independently of hydrogen; or an unsubstituted C1-C6 alkyl group, and more specifically, each independently of hydrogen; or an unsubstituted C1-C5 alkyl group.

[0120] According to the present invention, in the chemical formula V, R'' is specifically an unsubstituted C2-C 10 alkenyl group; or unsubstituted C2-C 10The alkynyl group may be, more specifically, an unsubstituted C2-C6 alkenyl group; or an unsubstituted C2-C6 alkynyl group, more specifically, an unsubstituted C2-C5 alkenyl group; or an unsubstituted C2-C5 alkynyl group.

[0121] According to the present invention, in the chemical formula V, R d and R e Specifically, these are, independently of each other, hydrogen; and unsubstituted C1-C 10 The alkyl group may be a siloxane group substituted with a siloxane group and / or a silane group; or an unsubstituted siloxane group, and more specifically, each independently may be hydrogen; an unsubstituted C1-C6 alkyl group; a siloxane group substituted with a siloxane group and / or a silane group; or an unsubstituted siloxane group, and more specifically, each independently may be hydrogen; an unsubstituted C1-C5 alkyl group; a siloxane group substituted with a siloxane group and / or a silane group; or an unsubstituted siloxane group. On the other hand, R d and R e If both are siloxane groups, R d and R e These may be linked together to form a ring consisting of siloxane bonds.

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

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[0125] According to the present invention, the weight ratio (A:B) of the compound (A) represented by chemical formula I to one or more compounds (B) selected from the compounds represented by chemical formulas II to V is 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, and 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, or 1 to 2:1. In this case, the compound represented by chemical formula I is abundant compared to the compounds represented by chemical formulas II to V that act as crosslinking agents, and crosslinks can be efficiently formed, resulting in the formation of a SEI layer with strong mechanical rigidity and improved battery stability.

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

[0127] (2) Organic solvents The aforementioned organic solvent is not limited as long as it is a non-aqueous solvent commonly used in lithium secondary batteries, which can minimize decomposition due to oxidation reactions during the charging and discharging process of the secondary battery and can exhibit the desired properties together with the additive.

[0128] The organic solvent may, but is not limited to, linear carbonates or cyclic carbonates, linear esters or cyclic esters, ethers, grime, nitriles (acetonitrile, SN, etc.), etc. 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 as the organic solvent.

[0129] On the other hand, specific examples of the aforementioned cyclic carbonate compounds include, but are not limited to, 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).

[0130] Specific examples of the linear carbonate compounds mentioned above 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 compounds mentioned above 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 aforementioned cyclic ester compounds include, but are not limited to, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0133] Specific examples of the aforementioned ether-based solvents 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 aforementioned glyme-based solvents have a higher dielectric constant and lower surface tension compared to linear carbonate-based organic solvents, and are solvents with low reactivity with metals. Examples include, but are not limited to, dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

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

[0136] On the other hand, ethylene carbonate and propylene carbonate, which are cyclic carbonate-based organic solvents, are preferred because they are high-viscosity organic solvents with high dielectric constants that easily dissociate lithium salts in the electrolyte. When such cyclic carbonates are mixed with low-viscosity, low-dielectric-constant linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate in appropriate proportions, it is possible to produce an electrolyte with high electrical conductivity, and therefore these can be used more preferably. In this case, the cyclic carbonates and linear carbonates may 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 serves as a medium for transferring ions. Typically, the lithium salt comprises one or more compounds selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiN(C2F5SO2)2, LiN(CF3SO2)2, CF3SO3Li, LiC(CF3SO2)3, LiC4BO8, LiTFSI, LiFSI, and LiClO4, and preferably contains LiPF6, but is not limited to these. On the other hand, the lithium salt may be used as a single type, or as a mixture of two or more types as needed.

[0138] According to the present invention, the lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, 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, allowing for smooth charging and discharging of the battery, and the viscosity of the electrolyte is appropriate, resulting in excellent wettability within 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 aforementioned other electrolyte additives are known electrolyte additives that can be further added to the non-aqueous electrolyte of the present invention, for example, vinylene carbonate, vinyl ethylene carbonate, catechol carbonate, α-bromo-γ-butyrolactone, methyl chloroformate, succinimide, N-benzyloxycarbonyloxysuccinimide, N-hydroxysuccinimide, N-chlorosuccinimide, methyl cinnamate, 1,3,5-tricyanobenzene (1,3,5-tricyanobenzene), tetracyanoquinodimethane, pyrocarbonate, cyclohexylbenzene, propane sultone, succinonitrile, adiponitrile, ethylene sulfate, propene sultone, fluoroethylene carbonate, LiPO2F2, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium These may include 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, LiBF4, etc.

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

[0142] Lithium-ion rechargeable battery The present invention provides a lithium secondary battery containing the non-aqueous electrolyte.

[0143] Specifically, the lithium secondary battery 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 according to the present invention.

[0144] At this time, the lithium secondary battery of the present invention can be manufactured by a conventional method known in the art. For example, after forming an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode, the electrode assembly is inserted into the inside of a battery case, and the non-aqueous electrolyte according to the present invention is injected to manufacture it.

[0145] (1) Positive electrode The positive electrode 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.

[0146] The positive electrode 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 a material obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel may be used. Also, 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., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-Z Ni Z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1O2 (where 0 < Y1 < 1, etc.), lithium-manganese-cobalt-based oxides (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where 0 < Z1 < 2, etc.), lithium-nickel-manganese-cobalt-based oxides (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2, etc.), or lithium-nickel-cobalt-transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r3 M s2 )O2 (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 the atomic fractions of the respective independent elements, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1, etc.), etc., and any one or two or more of these compounds may be included.

[0148] Among them, from the point of view of being able to improve the capacity characteristics and stability of the battery, the lithium metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (e.g., Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1)O2 etc.), or lithium nickel cobalt aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 (e.g., O2), etc., and considering the remarkable improvement effect of controlling the type and content ratio of constituent elements that form the lithium composite metal oxide, the lithium composite metal oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2, and Li(Ni 0.8 Mn 0.1 Co 0.1 ) may be O2, and one or more of these may be used as a mixture of two or more.

[0149] The positive electrode active material may be present 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 the solid matter in the positive electrode slurry excluding the solvent.

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

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

[0152] Typically, the binder may be present in an amount of 1% to 20% by weight, preferably 1% to 15% by weight, and more preferably 1% to 10% by weight, based on the total weight of the solid matter in the cathode slurry excluding the solvent.

[0153] The aforementioned conductive material is a component that further improves 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 is conductive. For example, graphite; carbon-based materials 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 may be used.

[0155] Typically, the conductive material may be present in an amount of 1% to 20% by weight, preferably 1% to 15% by weight, and more preferably 1% to 10% by weight, based on the total weight of the solid matter in the positive electrode slurry excluding the solvent.

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

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

[0158] For example, when a negative electrode is manufactured by coating a negative electrode slurry onto the negative electrode current collector, the negative electrode current collector generally has a thickness of 3 to 500 μm. Such a negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. Also, similar to the positive electrode current collector, the bonding 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 film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0159] The negative electrode active material may be natural graphite, artificial graphite, carbonaceous material; lithium-containing titanium composite oxide (LTO), Si, SiO x Metals (Me) that are Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe; alloys composed of the aforementioned metals (Me); oxides (MeO) of the aforementioned metals (Me) x Examples of negative electrode active materials include silicon (Si), silicon oxide (SiO2), and one or more selected from the group consisting of the aforementioned metals (Me) and carbon composites. Specifically, negative electrode active materials include silicon (Si), silicon oxide (SiO2), and silicon oxide (SiO2). x ), or silicon-based negative electrode active materials including silicon alloy may be used. In this case, a thin and stable SEI layer containing siloxane bonds is formed, which can further improve the high-temperature stability and lifespan characteristics of the battery.

[0160] The negative electrode active material may be present 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 the solid matter in the negative electrode slurry excluding the solvent.

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

[0162] Typically, the binder may be present in an amount of 1% to 20% by weight, preferably 1% to 15% by weight, and more preferably 1% to 10% by weight, based on the total weight of the solid matter in the negative electrode slurry excluding the solvent.

[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 is conductive, and may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive materials such as polyphenylene derivatives.

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

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

[0166] When using the metal itself as the negative electrode, it can be manufactured by a method such as physically bonding, rolling, or vapor-depositing the metal on the metal thin film itself or the negative electrode current collector. As the vapor deposition method, a method of electrically vapor-depositing or chemically vapor-depositing (chemical vapor deposition) the metal can be used.

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

[0168] (3) Separator Also, as the separator, a conventional porous polymer film that has been used as a separator, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, may be used alone or in a laminated form, or a conventional porous non-woven fabric, for example, a non-woven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc. may be used, but it is not limited thereto. 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 selectively used in a single-layer or multi-layer structure.

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

[0170] According to the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same can be provided. Since the battery module and battery pack include the lithium secondary battery having high capacity, high rate characteristics, and cycle characteristics, they can be used as a power source for medium to large 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 invention. It will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the described concept and technical idea, and it goes without saying that such variations and modifications fall within the scope of the appended claims.

[0172] Example of synthesis Synthesis Example 1. Preparation of the compound represented by chemical formula Ia 3.5 equivalents of 2,2,2-trifluoroethanol were placed in a two-necked round-bottom flask. A dropping funnel and a reflux condenser were connected, and the round-bottom flask was placed in an oil bath. The flask was then heated to 50°C, and while flowing nitrogen gas, 1 equivalent of trichlorovinylsilane was slowly added dropwise over 1 hour using the dropping funnel. After the addition was complete, the reaction was refluxed at 70°C while flowing nitrogen gas and allowed to proceed overnight. After cooling to room temperature, the pH was checked. If the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt produced in this process was filtered. After removing residual reactants and by-products by reducing the pressure at room temperature, the compound represented by chemical formula Ia was obtained by vacuum distillation at 60°C.

[0173] Compounds represented by chemical formula Ia 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 6.34(1H, dd), 6.18(1H, dd), 5.85(1H, dd), 4.12(6H, q)

[0174] Synthesis Example 2. Preparation of the compound represented by chemical formula II-a 2.5 equivalents of 2,2,2-trifluoroethanol were placed in a two-necked round-bottom flask. A dropping funnel and a reflux condenser were connected, and the round-bottom flask was placed in an oil bath. The flask was then heated to 50°C, and while flowing nitrogen gas, 1 equivalent of dichlorodivinylsilane was slowly added dropwise over 1 hour using the dropping funnel. After the addition was complete, the reaction was refluxed at 70°C while flowing nitrogen gas and allowed to proceed overnight. After cooling to room temperature, the pH was checked. If the pH was less than 7, it was neutralized with TEA (triethylamine), and the salt produced in this process was filtered. After removing residual reactants and by-products by reducing the pressure at room temperature, the compound represented by chemical formula II-a was obtained by vacuum distillation at 55°C.

[0175] Compounds represented by chemical formula II-a 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 6.32(2H, dd), 6.14(2H, dd), 5.84(2H, dd), 4.23(4H, q)

[0176] Synthesis Example 3. Preparation of the compound represented by chemical formula III-b Under a nitrogen atmosphere and an ice bath, dichlorodimethylsilane (1 equivalent) was slowly added dropwise over 1 hour to a Schlenk round-bottom flask containing allylmagnesium bromide (2.2 equivalents, 1 M in Ether). The reaction was then allowed to proceed overnight at room temperature. Five equivalents of saturated aqueous NH4Cl solution were added dropwise to the flask to terminate the reaction. After removing the aqueous solution by layer separation, the resulting organic layer was dried over CaCl2, and the precipitate was removed by filtration. After removing residual reactants and by-products under reduced pressure at room temperature, the compound represented by chemical formula III-b was obtained by vacuum distillation at 80°C.

[0177] Compounds represented by chemical formula III-b 1The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 5.77(2H, m), 4.85(4H, m), 1.53(4H, d), 0.00(6H, s)

[0178] Synthesis Example 4. Preparation of the compound represented by chemical formula III-j Under a nitrogen atmosphere and an ice bath, 3-(trichlorosilyl)propanenitrile (1 equivalent) was slowly added dropwise over 1 hour to a Schlenk round-bottom flask containing vinylmagnesium bromide (3.3 equivalents, 1 M in Ether). The reaction was then allowed to proceed overnight at room temperature. Seven equivalents of saturated aqueous NH4Cl solution were added dropwise to the flask to terminate the reaction. After removing the aqueous solution by layer separation, the resulting organic layer was dried over CaCl2, and the precipitate was removed by filtration. After removing residual reactants and by-products under reduced pressure at room temperature, the compound represented by chemical formula III-j was obtained by vacuum distillation at 120°C.

[0179] Compounds represented by chemical formula III-j 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) δ(ppm): 6.13(6H, m), 5.82(3H, m), 2.39(2H, t), 1.13(2H, t)

[0180] Synthesis Example 5. Preparation of the compound represented by chemical formula III-m Under a nitrogen atmosphere and ice bath, trichloro(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane (1 equivalent) was slowly added dropwise over 1 hour to a Schlenk round-bottom flask containing vinylmagnesium bromide (3.3 equivalents, 1 M in Ether). The reaction was then allowed to proceed overnight at room temperature. Seven equivalents of saturated aqueous NH4Cl solution were added dropwise to the flask to terminate the reaction. After removing the aqueous solution by layer separation, the resulting organic layer was dried over CaCl2, and the precipitate was removed by filtration. After removing residual reactants and by-products under reduced pressure at room temperature, the compound represented by chemical formula III-m was obtained by vacuum distillation at 110°C.

[0181] Compounds represented by the chemical formula III-m 1 The H-NMR data is as follows: 1 H-NMR(400MHz, CDCl3) 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 (Manufacturing of non-aqueous electrolytes) A non-aqueous electrolyte was prepared by adding 0.67 g of the compound represented by chemical formula Ia and 0.33 g of the compound represented by chemical formula II-a to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4.

[0183] (Manufacturing of secondary batteries) Cathode active material (LiNi 0.8 Co 0.1 Mn 0.1A cathode slurry (60% solids by weight) was prepared by adding O2, a conductive material (carbon black), and a binder (polyvinylidene fluoride) to N-methyl-2-pyrrolidone (NMP) in a weight ratio of 97.5:1:1.5. The cathode slurry was applied to one surface of a 15 μm thick cathode current collector (a thin aluminum film), and the cathode was manufactured by drying and roll pressing.

[0184] A negative electrode slurry (50% solids by weight) was prepared by adding a negative electrode active material (graphite:silicon oxide = 92:8 by weight ratio), a conductive material (carbon black), styrene-butadiene rubber, and carboxymethylcellulose to distilled water in a weight ratio of 95:1.5:1.5:2. The negative electrode slurry was applied to one surface of a 15 μm thick negative electrode current collector (Cu thin film), and the negative electrode was manufactured by drying and roll pressing.

[0185] In a dry room, an electrode assembly was manufactured by interposing a porous polypropylene separator between the manufactured positive electrode and negative electrode. Then, the assembly was placed in a battery case, the non-aqueous electrolyte was poured in, and the assembly was sealed to produce a pouch-type lithium secondary battery (battery capacity 6.24 mAh).

[0186] Example 2 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound represented by chemical formula II-a to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0187] Example 3 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound represented by chemical formula III-b to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0188] Example 4 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound represented by chemical formula III-j to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0189] Example 5 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound represented by chemical formula III-m to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0190] Example 6 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound tetravinylsilane (Sigma-Aldrich), represented by chemical formula IV-a, to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was then manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0191] Example 7 A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Tokyo Chemical Industries Co., Ltd.), represented by chemical formula Vb, to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A non-aqueous electrolyte was prepared by adding 0.5 g of the compound represented by chemical formula Ia and 0.5 g of the compound 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (Tokyo Chemical Industries Co., Ltd.), represented by chemical formula Vb. A lithium secondary battery was prepared in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0192] Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that an organic solution containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4 (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio) was used as the non-aqueous electrolyte.

[0193] Comparative Example 2 A non-aqueous electrolyte was prepared by adding 1 g of 1,3-propane sultone (Sigma-Aldrich) to 99 g of an organic solution containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4 (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio). A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0194] Comparative Example 3 A non-aqueous electrolyte was prepared by adding 1 g of TEOS (tetraethoxysilane) (Sigma-Aldrich) to 99 g of an organic solution containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4 (ethylene carbonate (EC): ethyl methyl carbonate (EMC) = 3:7 volume ratio). A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0195] Comparative Example 4 A non-aqueous electrolyte was prepared by adding 1 g of the compound represented by the chemical formula Ia to 99 g of an organic solution (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 volume ratio) containing 1.0 M LiPF6, 0.5 wt% VC, and 0.2 wt% LiBF4. A lithium secondary battery was manufactured in the same manner as in Example 1, except that the non-aqueous electrolyte prepared in this way was used.

[0196] [Table 1]

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

[0198] 1) Percentage change in volume after high-temperature storage (%) Each secondary battery manufactured in Examples 1-7 and Comparative Examples 1-4 was activated with a constant current (CC) of 0.1C. Next, using a PESCO5-0.5 charge / discharger (manufacturer: PNE Solutions Co., Ltd., 5V, 500mA) at 25°C, under constant current-constant voltage (CC-CV) charging conditions, the batteries were charged to 4.2V with a constant current of 0.3C, followed by a 0.05C current cut, and then discharged to 2.5V at 0.33C under CC conditions. This charge / discharge was considered one cycle, and two cycles were performed. Next, the batteries were fully charged with a constant current-constant voltage of 0.33C / 4.2V, discharged at 2.5C for 10 seconds at a SOC of 50%, and the initial resistance was calculated from the difference between the voltage before and after the 10-second discharge. Finally, the batteries were discharged with a constant current of 0.33C until the voltage reached 2.5V. Next, the lithium secondary batteries were degassed, and the initial volume was measured using a Two-pls TWD-150DM apparatus, with the batteries placed in a water-filled bowl at room temperature. Subsequently, each lithium secondary battery was fully charged with a constant current-voltage of 0.33C / 4.2V and stored at 60°C for 4 weeks (SOC 100%). After that, the volume after high-temperature storage was measured using a Two-pls TWD-150DM apparatus, with the batteries placed in a water-filled bowl at room temperature.

[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 rate of volume change, and the results are shown in Table 2 below.

[0200] Equation (1): Percentage change in volume after high-temperature storage (%) = {(Volume after high-temperature storage - Initial volume) / Initial volume} × 100

[0201] 2) Percentage increase in resistance after high-temperature storage (%) Each secondary battery manufactured in Examples 1-7 and Comparative Examples 1-4 was activated with a constant current (CC) of 0.1C. Next, using a PESCO5-0.5 charge / discharger (manufacturer: PNE Solutions Co., Ltd., 5V, 500mA) at 25°C, under constant current-constant voltage (CC-CV) charging conditions, the batteries were charged to 4.2V with a constant current of 0.3C, followed by a 0.05C current cut, and then discharged to 2.5V at 0.33C under CC conditions. This charge / discharge was considered one cycle, and two cycles were performed. Next, the batteries were fully charged with a constant current-constant voltage of 0.33C / 4.2V, discharged at 2.5C for 10 seconds at a SOC of 50%, and the initial resistance was calculated from the difference between the voltage before and after the 10-second discharge. Finally, the batteries were discharged with a constant current of 0.33C until the voltage reached 2.5V. Next, the batteries were degassed, charged at 4.2V, stored at 60°C for 4 weeks (SOC 100%), and then the resistance after high-temperature storage was measured while discharging at 2.5C for 10 seconds at SOC 50%.

[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 after high-temperature storage - Initial resistance) / Initial resistance} × 100

[0204] [Table 2]

[0205] Experimental Example 2: Cycle Characteristic Evaluation Each secondary battery manufactured in Examples 1-7 and Comparative Examples 1-4 was activated with a constant current (CC) of 0.1C. Next, using a PESCO5-0.5 charge / discharger (manufacturer: PNE Solutions Co., Ltd., 5V, 500mA) at 25°C, under constant current-constant voltage (CC-CV) charging conditions, the batteries were charged to 4.2V with a constant current of 0.3C, followed by a 0.05C current cut, and then discharged to 2.5V at 0.33C under CC conditions. This charge / discharge was considered one cycle, and two cycles were performed. Next, the batteries were fully charged with a constant current-constant voltage of 0.33C / 4.2V, discharged at 2.5C for 10 seconds at a SOC of 50%, and the initial resistance was calculated from the difference between the voltage before and after the 10-second discharge. Finally, the batteries were discharged with a constant current of 0.33C until the voltage reached 2.5V.

[0206] Next, the batteries were degassed and charged at 45°C with a constant current of 0.33C under a voltage drive range of 2.5V to 4.5V until they reached 4.2V. Charging continued at a constant voltage of 4.2V until the charging current reached 0.05C, at which point charging was terminated. After leaving them for 20 minutes, they were discharged with a constant current of 0.33C until they reached 2.5V. This charge-discharge cycle was considered one cycle, and 100 charge-discharge cycles were performed. During this process, the capacity after one cycle and the capacity after 100 cycles were measured using a PESCO5-0.5 charge / discharger (manufacturer: PNE Solutions Co., Ltd., 5V, 500mA), and the capacity retention rate was evaluated by substituting the capacity into the following formula (3). 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} × 100

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

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

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

[0211] [Table 3]

[0212] Referring to Table 2, it can be confirmed that the secondary batteries manufactured in Examples 1 to 7 exhibit 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. Furthermore, referring to Table 3, it can be confirmed that the secondary batteries manufactured in Examples 1 to 7 exhibit significantly superior 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 chemical formulas II to V are included as additives in the non-aqueous electrolyte, 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 with a covalently bonded polysiloxane network on the surface of the negative electrode, thereby doubling the robust durability of the SEI layer. As a result, we can confirm improvements in capacity retention rate and resistance increase rate.

[0213] Therefore, as in the present invention, when a compound represented by chemical formula I and one or more compounds selected from chemical formulas II to V are included as additives in a non-aqueous electrolyte, a low-resistance and robust SEI layer is formed, making it possible to provide a lithium secondary battery with excellent high-temperature stability and lifespan characteristics.

Claims

1. Organic solvents and Lithium salts and The compound represented by the following chemical formula I, A non-aqueous electrolyte for lithium secondary batteries comprising one or more compounds selected from those represented by the following chemical formulas II to V. 【Chemistry 1】 (Among the above chemical formulas I to V, R ａ C is a carbon atom substituted with one or more fluorine elements. １ -C １０ It is an alkyl group, R ｂ Each of these is independently either a C element that is substituted with one or more fluorine elements or an unsubstituted C element. １ -C １０ It is an alkyl group, R ｃ is, independently of each other, a substituted or unsubstituted C １ -C １０ alkyl group, and R' represents, independently, hydrogen; and either substituted or unsubstituted carbon. １ -C １０ alkyl group; or substituted or unsubstituted C １ -C １０ It is a heteroalkyl group, R'' is either a substituted or unsubstituted C ２ -C １０ The alkenyl group of; or a substituted or unsubstituted C ２ -C １０ It is an alkynyl group, R ｄ and R ｅ These are, independently, hydrogen; and substituted or unsubstituted carbon. １ -C １０ alkyl group; substituted or unsubstituted C １ -C １０ A heteroalkyl group; or a substituted or unsubstituted siloxane group, R ｄ and R ｅ If both are siloxane groups, R ｄ and R ｅ They may be linked to each other to form a ring consisting of siloxane bonds. n is either 2 or 3.

2. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the compound represented by the chemical formula I is one or more compounds selected from the compounds of the following chemical formulas I-a to I-f. 【Chemistry 2A】 【Chemistry 2B】

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

4. The non-aqueous electrolyte for a lithium secondary battery according to claim 1, wherein the compound represented by the chemical formula III is one or more compounds selected from the compounds of the following chemical formulas III-a to III-o. [Chemistry 4A] 【Chemistry 4B】 【Chemistry 4C】 [Transformation 4D]

5. The non-aqueous electrolyte for a lithium secondary battery according to claim 1, wherein the compound represented by the chemical formula IV is one or more compounds selected from the compounds of the following chemical formulas IV-a to IV-c. 【Transformation 5】

6. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, wherein the compound represented by the chemical formula V is one or more compounds selected from the compounds of the following chemical formulas V-a and V-b. 【Transformation 6】

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

1.

8. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, comprising the compound represented by the chemical formula I in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the non-aqueous electrolyte.

9. The non-aqueous electrolyte for lithium secondary batteries according to claim 1, comprising one or more compounds selected from those represented by chemical formulas II to V in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the non-aqueous electrolyte.

10. 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, A lithium secondary battery comprising a non-aqueous electrolyte for lithium secondary batteries according to any one of claims 1 to 9.

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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