Nonaqueous electrolyte for lithium secondary battery and lithium secondary battery containing same

Abstract

The present invention relates to a non-aqueous electrolyte for a lithium secondary battery, which contains a first additive containing a chromone compound, and a lithium secondary battery containing the same.

Description

[Technical Field]

[0001] The present invention claims the benefit of priority based on Korean Patent Application Nos. 10-2022-0155698, 10-2022-0155700, and 10-2022-0155701 filed on November 18, 2022, and Korean Patent Application No. 10-2023-0033302 filed on March 14, 2023, and all contents disclosed in the documents of these Korean patent applications are incorporated herein by reference.

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

[0003] In recent years, the application areas of lithium secondary batteries have rapidly expanded from power supply for electronic devices such as electrical, electronic, communication, and computer equipment to power storage and supply for large-area devices such as automobiles and power storage devices. Accordingly, there is an increasing demand for secondary batteries with high capacity, high output, and high stability. For lithium secondary batteries for automotive applications, high capacity, high output, and long life characteristics are becoming increasingly important.

[0004] On the other hand, when lithium secondary batteries are repeatedly charged and discharged and exposed to high temperatures, decomposition of the electrolyte accelerates, resulting in gas generation within the cell. In recent years, the high-voltage positive electrodes used in lithium secondary batteries have been causing the decomposition of certain solvents, further increasing gas generation.

[0005] Furthermore, high-capacity positive electrodes have low lattice oxygen stability of the positive electrode active material under high-pressure operating conditions, which leads to the generation of oxygen gas from the positive electrode active material, resulting in a chain reaction of decomposition. Research is underway to solve this gas problem and improve the performance, lifespan, and stability of lithium secondary batteries. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] KR2006-0037592A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a non-aqueous electrolyte for a lithium secondary battery, and a lithium secondary battery, which can minimize problems caused by oxygen gas by capturing oxygen gas generated from a positive electrode active material, and can improve the life and stability of the lithium secondary battery by suppressing decomposition of the non-aqueous electrolyte for the lithium secondary battery. [Means for solving the problem]

[0008] In order to solve the above problems, 1) the present invention provides a non-aqueous electrolyte for a lithium secondary battery, which includes a first additive containing a compound represented by the following Chemical Formula 1:

[0009] [ka]

[0010] In the above Chemical Formula 1, R1, R3 to R6 may be the same or different, and each independently represent a hydrogen atom, a halogen atom, *-L1-C≡N, *-L2-C(═O)R7, *-L3-NR8R9, *-L4-OR 10 , C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R2 is hydrogen, halogen, *-L5-C≡N, *-L6-C(=O)R 11 , *-L7-NR 12 R 13 , *-L8-OR 14 , C1~C 20 or C2-C 20 is an alkynyl group of the formula R7~R 14may be the same or different, and each independently represents hydrogen, *-L9-OR 15 , C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R 15 is hydrogen, C1 to C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula L1 to L9 may be the same or different, and each independently represent a direct bond or C1 to C 10 is an alkylene group, R1 to R6 are not all hydrogen atoms at the same time; one or more of R1 to R6 are halogen atoms, and the remaining five of R1 to R6 are not all hydrogen atoms at the same time.

[0011] 2) The present invention can provide the nonaqueous electrolyte solution for a lithium secondary battery according to 1) above, wherein the compound represented by Chemical Formula 1 includes one or more compounds represented by the following Chemical Formulas 1-1 to 1-22: [ka] [ka]

[0012] In the chemical formulas 1-1 to 1-22, R1', R3' to R6' may be the same or different, and each independently represent a halogen, *-L1'-C≡N, *-L2'-C(═O)R7', *-L3'-NR8'R9', *-L4'-OR 10 ', C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R2' is halogen, *-L5'-C≡N, *-L6'-C(=O)R 11 ',*-L7'-NR 12 'R 13',*-L8'-OR 14 ', C1~C 20 or C2-C 20 is an alkynyl group of the formula R7'~R 14 ' may be the same or different, and each independently represents hydrogen, *-L9'-OR 15 ', C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R 15 ' is hydrogen, C1 to C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula L1' to L9' may be the same or different, and each independently represent a direct bond or a C1 to C 10 is an alkylene group of the formula:

[0013] 3) The present invention can provide the nonaqueous electrolyte solution for a lithium secondary battery according to 1) above, wherein the compound represented by Chemical Formula 1 includes one or more compounds represented by the following chemical formulas: [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0014] 4) The present invention may provide the non-aqueous electrolyte solution for a lithium secondary battery according to any one of 1) to 3), wherein the content of the first additive is 0.01 to 10.00 parts by weight per 100 parts by weight of the non-aqueous electrolyte solution for a lithium secondary battery.

[0015] 5) The present invention can provide the nonaqueous electrolyte solution for a lithium secondary battery according to any one of 1) to 4), which contains a second additive containing one or more compounds represented by the following Chemical Formulas 2 to 4:

[0016] [ka]

[0017] In the above Chemical Formula 2, X 21 is *-S(=O)-* or *-S(=O)2-*, X 22 and X 23 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula:

[0018] [ka]

[0019] In the above Chemical Formula 3, Y 31 and L 33 may be the same or different and each independently represents *-S(=O)-* or *-S(=O)2-*, Y 32 , Y 33 , L 31 , L 32 , L 34 , and L 35 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula R 31 is hydrogen, C1 to C10 Alkyl groups of C2 to C 10 or an alkenylene group of C2 to C 10 is an alkynylene group of the formula:

[0020] [ka]

[0021] In the above Chemical Formula 4, Z 42 , Z 45 , and L 43 may be the same or different and each independently represents *-S(=O)-* or *-S(=O)2-*, Z 41 , Z 43 , Z 44 , Z 46 , L 41 , L 42 , L 44 , and L 45 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula:

[0022] 6) The present invention can provide the nonaqueous electrolyte solution for a lithium secondary battery according to 5) above, wherein the compound represented by Chemical Formula 2 includes one or more of compounds represented by the following Chemical Formulas 2-1 to 2-4, the compound represented by Chemical Formula 3 includes one or more of compounds represented by the following Chemical Formulas 3-1 to 3-3, and the compound represented by Chemical Formula 4 includes one or more of compounds represented by the following Chemical Formulas 4-1 to 4-3: [ka]

[0023] 7) The present invention can provide the non-aqueous electrolyte solution for a lithium secondary battery according to 5) or 6), wherein the content of the second additive is 0.01 to 5.00 parts by weight per 100 parts by weight of the non-aqueous electrolyte solution for a lithium secondary battery.

[0024] 8) The present invention can provide the nonaqueous electrolyte solution for a lithium secondary battery according to any one of 1) to 7), wherein the nonaqueous electrolyte solution for a lithium secondary battery contains one or more of a lithium salt and an organic solvent.

[0025] 9) The present invention provides a lithium secondary battery comprising the nonaqueous electrolyte for a lithium secondary battery according to any one of 1) to 8) above, a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and a separator interposed between the positive electrode and the negative electrode.

[0026] 10) The present invention can provide the lithium secondary battery according to 9) above, wherein the positive electrode active material includes at least one of an over-lithiated layered oxide represented by the following chemical formula 5 and an NCM-based lithium transition metal composite oxide represented by the following chemical formula 6:

[0027] <Chemical formula 5> xLi2MnO3·(1-x)Li a1 Ni b1 Co c1 Mn d1 M 1 e1 O2

[0028] In the above Chemical Formula 5, 0 <x<1、0≦a1≦2、0≦b1≦1、0≦c1≦1、0≦d1≦1、0≦e1≦1、a1+b1+c1+d1+e1=2であり、 M 1 contains one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc.

[0029] <Chemical formula 6> Li a2 Ni b2 Co c2 Mn d2 M 2 e2O2

[0030] In the above Chemical Formula 6, 0.9≦a2≦1.1, 0.7≦b2<1, 0≦c2<1, 0 <d2<1、0≦e2<1、b2+c2+d2+e2=1であり、 M 2 contains one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc. [Effects of the Invention]

[0031] The nonaqueous electrolyte for a lithium secondary battery and the lithium secondary battery of the present invention can minimize problems caused by oxygen gas by capturing oxygen gas generated at the positive electrode, and can improve the performance, life, and stability of the lithium secondary battery by suppressing decomposition of the nonaqueous electrolyte for a gaseous lithium secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0032] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way 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 explain their inventions.

[0033] The terms used in the present invention are merely used to describe specific 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 "comprise" or "have" and the like 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 possibility of addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0034] In this specification, the term "on" refers not only to a case where one structure is formed directly on top of another structure, but also to a case where a third structure is interposed between the structures.

[0035] In the present invention, the alkyl group refers to a linear or cyclic alkyl group, and the number of carbon atoms is not particularly limited, but may be any of C1 to C 20 alkyl group, preferably C1 to C 15 alkyl groups, more preferably C1 to C 10 The alkyl group may be an alkyl group of any one of the above, most preferably a C1 to C5 alkyl group. The alkyl group may be further substituted with other substituents. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a 1-methylbutyl group, a 1-ethylbutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an n-hexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, an n-hexyl group, a 2-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, a n-hexyl group, a 2-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, a n-hexyl group, a 2-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, a n-hexyl group, a 2-methylpentyl group, a 2-hexylbutyl ... Examples of alkyl groups include, but are not limited to, ethyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethylpropyl, 1,1-dimethylpropyl, isohexyl, 2-methylpentyl, 4-methylhexyl, and 5-methylhexyl groups.

[0036] In the present invention, the alkylene group has the same definition as the alkyl group described above, except that it is a divalent group.

[0037] In the present invention, the alkenyl group means a linear or cyclic alkenyl group, and the number of carbon atoms is not particularly limited, but may be any of C2 to C6. 20 Alkenyl groups, preferably C2 to C 15 Alkenyl groups of the formula C2 to C610 The alkenyl group may be an alkenyl group of any one of the above, most preferably a C2 to C5 alkenyl group. The alkenyl group may be further substituted with other substituents. Examples of the alkenyl group include, but are not limited to, vinyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 3-methyl-1-butenyl, 1,3-butadienyl, allyl, 1-phenylvinyl-1-yl, 2-phenylvinyl-1-yl, 2,2-diphenylvinyl-1-yl, 2-phenyl-2-(naphthyl-1-yl)vinyl-1-yl, 2,2-bis(diphenyl-1-yl)vinyl-1-yl, stilbenyl, and styrenyl.

[0038] In the present invention, the alkenylene group has the same definition as the alkenyl group described above, except that it is a divalent group.

[0039] In the present invention, the alkynyl group means a linear or cyclic alkynyl group, and the number of carbon atoms is not particularly limited, but may be any of C2 to C6. 20 Alkynyl groups, preferably C2 to C 15 Alkynyl groups of the formula C2 to C6 10 The alkynyl group may be an alkynyl group of any one of the above, most preferably an alkynyl group of C2 to C5. Examples of the alkynyl group include alkynyl groups such as ethynyl, propynyl, 2-methyl-2-propynyl, 2-butynyl, and 2-pentynyl, but are not limited to these.

[0040] In the present invention, the alkynylene group has the same definition as the alkynyl group described above, except that it is a divalent group.

[0041] In the present invention, the aryl group refers to a monocyclic or polycyclic aryl group, and the number of carbon atoms is not particularly limited, but it is preferably C6 to C8. 20 an aryl group, preferably C6 to C 18 an aryl group, more preferably C2 to C 12The aryl group may be an aryl group of the formula (I). The aryl group may be further substituted with other substituents. Here, the term "polycyclic" refers to a group in which the aryl group is directly linked to or condensed with other ring groups. Specific examples of the aryl group include, but are not limited to, a phenyl group, a biphenyl group, a triphenyl group, a naphthyl group, and an anthryl group.

[0042] In the present invention, the arylene group has the same definition as the aryl group, except that it is a divalent group.

[0043] In the present invention, halogen can include one or more of F, Cl, Br, I, and At.

[0044] In the present invention, "*" indicates a binding position.

[0045] 1.Non-aqueous electrolyte for lithium secondary batteries A non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention includes a first additive containing a compound represented by the following Chemical Formula 1:

[0046] [ka]

[0047] In the above Chemical Formula 1, R1, R3 to R6 may be the same or different, and each independently represent a hydrogen atom, a halogen atom, *-L1-C≡N, *-L2-C(═O)R7, *-L3-NR8R9, *-L4-OR 10 , C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R2 is hydrogen, halogen, *-L5-C≡N, *-L6-C(=O)R 11 , *-L7-NR 12 R 13 , *-L8-OR 14 , C1~C 20 or C2-C20 is an alkynyl group of the formula R7~R 14 may be the same or different, and each independently represents hydrogen, *-L9-OR 15 , C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R 15 is hydrogen, C1 to C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula L1 to L9 may be the same or different, and each independently represent a direct bond or C1 to C 10 is an alkylene group, R1 to R6 are not all hydrogen at the same time; or one or more of R1 to R6 are halogen and the remaining five of R1 to R6 are not all hydrogen at the same time.

[0048] The compound represented by Chemical Formula 1 contains a chromone-based structure that captures oxygen gas generated at the positive electrode, thereby minimizing problems caused by oxygen gas. In addition, the compound represented by Chemical Formula 1 contains an electron-withdrawing group as a substituent, which has a strong binding strength with active oxygen, thereby reducing the amount of gas generated.

[0049] On the other hand, when R2 is an aryl group, the molecular structure is stabilized by the pi bond, the ability to capture active oxygen is weakened, and the amount of gas generated as a by-product increases relatively. Also, if one of R1 to R6 is a halogen and the rest are hydrogen, a side reaction may occur to produce halogen acid, which may degrade the performance of the lithium secondary battery.

[0050] When at least one of R1 to R6 is a halogen and the remaining five of R1 to R6 are not all hydrogen, the electron-withdrawing effect of the halogen increases the binding strength with active oxygen. Furthermore, because the compound represented by Formula 1 contains an electron-withdrawing group as a substituent, the remaining substituent can stabilize the electrons generated when the compound binds with active oxygen. As a result, the generation of halogen acid can be minimized, improving the performance of lithium secondary batteries.

[0051] If one of R1 to R6 is a halogen and the remaining five of R1 to R6 are simultaneously hydrogen, a side reaction may occur to produce halogen acid, which may degrade the performance of the lithium secondary battery.

[0052] Additionally, in order for the compound to maintain its original structure and allow active oxygen to be added, unsaturated hydrocarbons are required rather than saturated hydrocarbons. The addition of active oxygen occurs in the direction of the Michael-type unsaturated double bond. However, compounds that lack a double bond in part of the core, such as chromanone, have very poor oxygen-capturing ability because they lack active sites that can react with active oxygen. As a result, it is difficult to achieve oxygen gas inhibition.

[0053] The compound represented by Chemical Formula 1 may include one or more of the compounds represented by the following Chemical Formulas 1-1 to 1-22. [ka] [ka]

[0054] In the chemical formulas 1-1 to 1-22, R1', R3' to R6' may be the same or different, and each independently represent a halogen, *-L1'-C≡N, *-L2'-C(═O)R7', *-L3'-NR8'R9', *-L4'-OR10 ', C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R2' is halogen, *-L5'-C≡N, *-L6'-C(=O)R 11 ',*-L7'-NR 12 'R 13 ',*-L8'-OR 14 ', C1~C 20 or C2-C 20 is an alkynyl group of the formula R7'~R 14 ' may be the same or different, and each independently represents hydrogen, *-L9'-OR 15 ', C1~C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula R 15 ' is hydrogen, C1 to C 20 Alkyl groups of C2 to C 20 Alkynyl groups of C6 to C 20 is an aryl group of the formula L1' to L9' may be the same or different, and each independently represent a direct bond or a C1 to C 10 is an alkyl group.

[0055] Only when an electron-withdrawing group is present as a substituent can the positive charge of the carbon that can bind to active oxygen increase, and as a result, the binding strength with active oxygen increase. To maximize this effect, R1 to R6 may be independently the same or different from each other and may be selected from halogen, *-C≡N, *-C(=O)R7, *-NR8R9, *-OR 10 , C1~C 10 Alkyl groups of C6 to C 12 It is preferable that the aryl group is an aryl group represented by the formula:

[0056] The compound represented by Chemical Formula 1 may include one or more compounds represented by the following chemical formulas: [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0057] Specifically, the compound represented by Chemical Formula 1-1 may include one or more of the compounds represented by Chemical Formulas 1-1-1 to 1-1-7.

[0058] The compound represented by Chemical Formula 1-2 may include one or more of the compounds represented by Chemical Formulas 1-2-1 to 1-2-4.

[0059] The compound represented by Chemical Formula 1-3 may include the compound represented by Chemical Formula 1-3-1.

[0060] The compound represented by Chemical Formula 1-4 may include one or more of the compounds represented by Chemical Formula 1-4-1 and Chemical Formula 1-4-2.

[0061] The compound represented by Chemical Formula 1-5 may include one or more of the compounds represented by Chemical Formula 1-5-1 and Chemical Formula 1-5-2.

[0062] The compound represented by Chemical Formula 1-6 may include one or more of the compounds represented by Chemical Formula 1-6-1 and Chemical Formula 1-6-2.

[0063] The compound represented by Chemical Formula 1-7 may include one or more of the compounds represented by Chemical Formula 1-7-1 and Chemical Formula 1-7-2.

[0064] The compound represented by Chemical Formula 1-8 may include one or more of the compounds represented by Chemical Formulas 1-8-1 to 1-8-3.

[0065] The compound represented by Chemical Formula 1-9 may include one or more of the compounds represented by Chemical Formulas 1-9-1 to 1-9-15.

[0066] The compound represented by Chemical Formula 1-10 may include one or more of the compounds represented by Chemical Formulas 1-10-1 to 1-10-18.

[0067] The compound represented by Chemical Formula 1-11 may include the compound represented by Chemical Formula 1-11-1.

[0068] The compound represented by Chemical Formula 1-12 may include one or more of the compounds represented by Chemical Formulas 1-12-1 to 1-12-3.

[0069] The compound represented by Chemical Formula 1-13 may include one or more of the compounds represented by Chemical Formulas 1-13-1 to 1-13-3.

[0070] The compound represented by Chemical Formula 1-14 may include one or more of the compounds represented by Chemical Formula 1-14-1 and Chemical Formula 1-14-2.

[0071] The compound represented by Chemical Formula 1-15 may include the compound represented by Chemical Formula 1-15-1.

[0072] The compound represented by Chemical Formula 1-16 may include one or more of the compounds represented by Chemical Formulas 1-16-1 to 1-16-4.

[0073] The compound represented by Chemical Formula 1-17 may include the compound represented by Chemical Formula 1-17-1.

[0074] The compound represented by Chemical Formula 1-18 may include one or more of the compounds represented by Chemical Formulas 1-18-1 to 1-18-3.

[0075] The compound represented by Chemical Formula 1-19 may include the compound represented by Chemical Formula 1-19-1.

[0076] The compound represented by Chemical Formula 1-20 may include one or more of the compounds represented by Chemical Formulas 1-20-1 to 1-20-5.

[0077] The compound represented by Chemical Formula 1-21 may include the compound represented by Chemical Formula 1-21-1.

[0078] The compound represented by Chemical Formula 1-22 may include the compound represented by Chemical Formula 1-22-1.

[0079] The content of the compound represented by Chemical Formula 1 may be 0.01 to 10.00 parts by weight, preferably 0.01 to 5.00 parts by weight, and more preferably 0.10 to 1.00 parts by weight, relative to 100 parts by weight of the nonaqueous electrolyte solution for a lithium secondary battery. When the above conditions are satisfied, the SEI layer derived from the compound represented by Chemical Formula 1 can have a thickness that allows smooth lithium ion migration. Furthermore, the SEI layer has strong mechanical rigidity, improving the stability of the lithium secondary battery. Furthermore, an increase in the internal resistance of the lithium secondary battery can be prevented, thereby preventing a decrease in the capacity of the lithium secondary battery.

[0080] The non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention may contain a second additive containing one or more compounds represented by the following chemical formulas 2 to 4.

[0081] A non-aqueous electrolyte solution for a lithium secondary battery, comprising a second additive containing one or more compounds represented by the following chemical formulas 2 to 4: [ka]

[0082] In the above Chemical Formula 2, X 21 is *-S(=O)-* or *-S(=O)2-*, X 22 and X 23 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula:

[0083] [ka]

[0084] In the above Chemical Formula 3, Y 31 and L 33 may be the same or different and each independently represent *-S(=O)-* or *-S(=O)2-*, Y 32 , Y 33 , L 31 , L 32 , L 34 , and L 35 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula R 31 is hydrogen, C1 to C 10 Alkyl groups of C2 to C 10 or an alkenylene group of C2 to C 10 is an alkynylene group of the formula:

[0085] [ka]

[0086] In the above Chemical Formula 4, Z 42 , Z 45 , and L 43 may be the same or different and each independently represent *-S(=O)-* or *-S(=O)2-*, Z 41 , Z 43 , Z 44 , Z 46 , L 41 , L 42 , L 44 , and L 45 may be the same or different, and each independently represents a direct bond, —O—, or C1 to C 10 is an alkylene group of the formula:

[0087] In the above Chemical Formula 3, preferably, Y 32 , Y 33 , L 31 , L 32 , L 34 , and L 35 may be the same or different, and each independently may be a direct bond, -O-, or a C1 to C5 alkylene group. 31 may be hydrogen, a C1 to C5 alkyl group, a C2 to C5 alkenylene group, or a C2 to C5 alkynylene group.

[0088] In the above chemical formula 4, preferably, Z 41 , Z 43 , Z 44 , Z 46 , L 41 , L 42 , L 44、 and L 45 may be the same or different and each independently represents a direct bond, *-O-*, or a C1 to C5 alkylene group.

[0089] The second additive has a relatively high reduction potential and can be reduced before the electrolyte in the lithium secondary battery. As a result, unnecessary decomposition of the electrolyte can be prevented. In addition, the compounds represented by Chemical Formulas 2 to 4 contain sulfur in their molecules, which allows the formation of a stronger SEI layer. Here, the SEI layer may contain components such as Li(SO3CH3) and Li2SO3.

[0090] The compound represented by Chemical Formula 2 may include one or more of the compounds represented by the following Chemical Formulas 2-1 to 2-4. [ka]

[0091] The compound represented by Chemical Formula 3 may include one or more of the compounds represented by the following Chemical Formulas 3-1 to 3-3. [ka]

[0092] The compound represented by Chemical Formula 4 may include one or more of the compounds represented by the following Chemical Formulas 4-1 to 4-3. [ka]

[0093] The content of the second additive may be 0.01 to 5.00 parts by weight, preferably 0.05 to 3.00 parts by weight, and more preferably 0.10 to 1.00 parts by weight, based on 100 parts by weight of the nonaqueous electrolyte for lithium secondary batteries. When the above conditions are met, an SEI layer of an appropriate thickness is formed on the negative electrode, which can suppress performance degradation and gas generation due to side reactions and improve the life stability of the lithium secondary battery.

[0094] Even when the second additive contains two or more of the compounds represented by Formulas 2 to 4, the content of the second additive can satisfy the above-mentioned conditions.

[0095] The non-aqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention may contain at least one of a lithium salt and an organic solvent.

[0096] The lithium salt may be any of those commonly used in non-aqueous electrolytes for lithium secondary batteries, without any particular limitation. + and as an anion, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO4 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , BF2C2O4CHF - , PF4C2O4 - , PF2C4O8 - , PO2F2 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 -, and SCN - It may contain one or more of the following:

[0097] Specifically, the lithium salts include LiPF6, LiClO4, LiBF4, LiN(FSO2)2 (LiFSI), LiN(SO2CF3)2 (LiTFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), LiSO3CF3, LiPO2F2, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiFOB), lithium difluoro(bisoxalato)phosphate (LiDFOP), lithium tetrafluoro(oxalate)phosphate (LiTFOP), and lithium fluoromalonato(difluoro)borate (LiTFOP). The lithium fluoride may be one or more of LiF, LiFePO, LiF ...

[0098] The concentration of the lithium salt in the non-aqueous organic solution containing the lithium salt and the organic solvent may be 0.5 to 4.0 M, specifically 0.5 to 3.0 M, more specifically 0.8 to 2.0 M. When the concentration of the lithium salt is within the above range, the effects of improving low-temperature output and cycle characteristics are sufficiently ensured, and excessive increases in viscosity and surface tension are prevented, resulting in appropriate electrolyte impregnation.

[0099] The organic solvent may be any of various organic solvents commonly used in lithium electrolytes without limitation. For example, the organic solvent may be a cyclic carbonate solvent, a linear carbonate solvent, a linear ester solvent, a cyclic ester solvent, a nitrile solvent, or a mixture thereof. Preferably, the organic solvent may include at least one of a cyclic carbonate solvent, a linear carbonate solvent, and a linear ester solvent, and more preferably, at least one of a cyclic carbonate solvent and a linear carbonate solvent.

[0100] The cyclic carbonate solvent is a high-viscosity organic solvent that has a high dielectric constant and therefore easily dissociates the lithium salt in the electrolyte. The cyclic carbonate solvent may include one or more of ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate, and preferably includes one or more of ethylene carbonate and propylene carbonate.

[0101] The linear carbonate solvent is an organic solvent having low viscosity and low dielectric constant, and may include one or more of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate, and preferably one or more of ethyl methyl carbonate, dimethyl carbonate, and diethyl carbonate.

[0102] The organic solvent is preferably a mixture of a cyclic carbonate solvent and a linear carbonate solvent in order to produce an electrolyte solution having high ionic conductivity.

[0103] The linear ester solvent may include one or more of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate, and preferably one or more of methyl propionate, ethyl propionate, and propyl propionate.

[0104] The cyclic ester solvent may include one or more of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0105] The nitrile solvent may include one or more of succinonitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, and preferably includes succinonitrile.

[0106] In the total weight of the nonaqueous electrolyte solution, the remainder excluding other components other than the organic solvent, for example, the compound represented by Chemical Formula 1, the additive, and the lithium salt, is the organic solvent unless otherwise specified.

[0107] The nonaqueous electrolyte for a lithium secondary battery according to an embodiment of the present invention may optionally further include the following additives, as needed, to prevent electrode collapse due to decomposition of the electrolyte in a high-voltage environment, or to further improve low-temperature high-rate discharge characteristics, high-temperature stability, overcharge prevention, and effects of suppressing battery expansion at high temperatures.

[0108] The additive may include one or more of a cyclic carbonate-based compound, a halogen-substituted carbonate-based compound, a sulfate-based compound, a phosphate-based or phosphite-based compound, a borate-based compound, a nitrile-based compound, an amine-based compound, a silane-based compound, a benzene-based compound, and a lithium salt-based compound.

[0109] The cyclic carbonate compound may include at least one of vinylene carbonate and vinylethylene carbonate, and specifically may include vinylene carbonate.

[0110] The halogen-substituted carbonate compound may include fluoroethylene carbonate (FEC).

[0111] The sulfate-based compound is a material that can be electrically decomposed on the surface of the negative electrode to form a stable SEI layer that does not crack even when stored at high temperatures, and may include one or more of ethylene sulfate, trimethylene sulfate, and methyl trimethylene sulfate.

[0112] The phosphate or phosphite compounds may include one or more of lithium difluoro(bisoxalato)phosphate, lithium difluorophosphate, tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, tris(2,2,2-trifluoroethyl)phosphate, and tris(trifluoroethyl)phosphite.

[0113] The borate-based compound may include lithium tetraphenylborate.

[0114] The nitrile compound may include one or more of succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, ethylene glycol bis(2-cyanoethyl)ether, 1,3,6-hexanetricarbonitrile, 1,4-dicyano-2-butene, and 1,2,3-tris(2-cyanoethyl)propane.

[0115] The amine-based compound may include one or more of triethanolamine and ethylenediamine, and the silane-based compound may include tetravinylsilane.

[0116] The benzene-based compound may include one or more of monofluorobenzene, difluorobenzene, trifluorobenzene, and tetrafluorobenzene.

[0117] The lithium salt-based compound is a compound different from the lithium salt contained in the non-aqueous electrolyte solution, and may include one or more of lithium difluorophosphate (LiDFP; LiPOF), lithium bis(oxalato)borate (LiBOB; LiB(C0)), lithium tetrafluoroborate (LiBF), and lithium difluoro(bis(oxalato)phosphate).

[0118] Preferably, the non-aqueous electrolyte according to one embodiment of the present invention may further include one or more additives selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, ethylene sulfate, succinonitrile, adiponitrile, ethylene glycol bis(2-cyanoethyl)ether, 1,3,6-hexanetricarbonitrile, 1,4-dicyano-2-butene, 1,2,3-tris(2-cyanoethyl)propane, lithium difluorooxalatoborate, lithium tetrafluoroborate, lithium difluoro(bisoxalato)phosphate, and lithium difluorophosphate. In this case, the additives decompose more quickly than the compound represented by Chemical Formula 1 to form a film, thereby increasing the amount of the compound represented by Chemical Formula 1 remaining after the activation process, thereby improving the long-term performance of the battery.

[0119] The content of the additive may be 0.1 wt % to 10.0 wt %, and preferably 0.3 wt % to 5.0 wt %, based on the total weight of the non-aqueous electrolyte solution. When the content of the additive is within the above range, the side reaction suppression effect due to the formation of a coating on the positive electrode and the negative electrode can be obtained.

[0120] 2. Lithium secondary batteries A lithium secondary battery according to another embodiment of the present invention includes the nonaqueous electrolyte for a lithium secondary battery according to one embodiment of the present invention, a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a separator interposed between the positive electrode and the negative electrode.

[0121] The non-aqueous electrolyte for the lithium secondary battery has been described above, so a description thereof will be omitted and other components will be described below.

[0122] 1) Positive electrode The positive electrode according to the present invention includes a positive electrode active material and can be manufactured by coating a positive electrode slurry containing the positive electrode active material, a binder, a conductive material, a solvent, etc., on a positive electrode current collector, followed by drying and rolling.

[0123] 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 those obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used.

[0124] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and may include one or more of LCO (LiCoO2); LNO (LiNiO2); LMO (LiMnO2); LiMn2O4, LiCoPO4; LFP (LiFePO4); and lithium composite transition metal oxides containing nickel (Ni), cobalt (Co), and manganese (Mn).

[0125] More specifically, the lithium metal oxide is a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, Li2MnO3, 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 Y1 O2 (where, 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where, 0 < Y2 < 1), LiMn 2-Z1 Co Z1 O4 (where, 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (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.), and lithium-nickel-cobalt-manganese-transition metal (M) oxides (e.g., Li(Ni p2 Co q2 Mn r3 M S2 )O2 (where M is one or more 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 independent elements, respectively, 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.) may be included.

[0126] According to the present invention, the positive electrode active material may include one or more of an over-lithiated layered oxide represented by the following Chemical Formula 5 and an NCM-based lithium composite transition metal oxide represented by the following Chemical Formula 6 for improving the capacity of the battery.

[0127] <Chemical Formula 5> xLi2MnO3·(1 - x)Li a1 Ni b1 Co c1 Mn d1 M 2 e1 O2

[0128] In the Chemical Formula 5, 0 < x < 1, 0 ≤ a1 ≤ 2, 0 ≤ b1 ≤ 1, 0 ≤ c1 ≤ 1, 0 ≤ d1 ≤ 1, 0 ≤ e1 ≤ 1, and a1 + b1 + c1 + d1 + e1 = 2, M 1 includes one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc.

[0129] <Chemical Formula 6> Li a2 Ni b2 Co c2 ​d2 M 2 e2 O2

[0130] In the above Chemical Formula 6, 0.9≦a2≦1.1, 0.7≦b2<1, 0≦c2<1, 0 <d2<1、0≦e2<1、b2+c2+d2+e2=1であり、 M2 includes one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc.

[0131] Meanwhile, when the positive electrode active material includes an overlithiated layered oxide or an NCM-based lithium composite transition metal oxide, high-voltage driving conditions are required, and corrosion of the electrode surface and gas generation due to decomposition of the electrolyte may become more problematic. However, the lithium secondary battery according to the present invention has the advantage of not having such problems while having a high capacity by including the above-mentioned nonaqueous electrolyte.

[0132] The positive electrode active material may be included in an amount of 80 wt% to 99 wt%, specifically 90 wt% to 99 wt%, based on the total weight of the solid content in the positive electrode slurry. If the content of the positive electrode active material is less than 80 wt%, the energy density may be reduced, resulting in a decrease in capacity.

[0133] The binder is a component that aids in binding the active material and conductive material, etc., and in binding to the current collector, and may be added in an amount of 1 wt % to 30 wt % based on the total weight of the solid content in the positive electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0134] The conductive material is a substance that imparts conductivity to the battery without causing any chemical change, and may be added in an amount of 0.5 wt % to 20 wt % based on the total weight of the solid content in the positive electrode slurry.

[0135] The conductive material may be selected from, for example, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; graphite powder such as natural graphite, artificial graphite, carbon nanotubes, and graphite; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0136] The solvent for the positive electrode slurry may include an organic solvent such as N-methyl-2-pyrrolidone, and may be used in an amount that provides a suitable viscosity when the positive electrode active material, binder, conductive material, etc. are contained. For example, the positive electrode slurry containing the positive electrode active material, binder, and conductive material may be contained so that the solids concentration is 40 wt % to 90 wt %, preferably 50 wt % to 80 wt %.

[0137] 2) Negative electrode The negative electrode includes a negative electrode active material and can be manufactured by coating a negative electrode slurry containing the negative electrode active material, a binder, a conductive material, and a solvent on a negative electrode current collector, followed by drying and rolling.

[0138] The negative electrode current collector generally has a thickness of 3 μm to 500 μm. There are no particular limitations on the negative electrode current collector, so long as it does not cause chemical changes in the battery and has high conductivity. Examples of such a negative electrode current collector include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, and aluminum-cadmium alloys. Similarly to the positive electrode current collector, the surface may be provided with fine irregularities to strengthen the binding force of the negative electrode active material, and the negative electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0139] In addition, the negative electrode active material may include one or more of a carbon material capable of reversibly intercalating / deintercalating lithium ions; a metal or an alloy of such a metal and lithium; a metal composite oxide; a material capable of doping and dedoping lithium; lithium metal; and a transition metal oxide.

[0140] The carbonaceous material capable of reversibly intercalating / deintercalating lithium ions may be any carbonaceous negative electrode active material commonly used in lithium ion secondary batteries, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination of these. Examples of crystalline carbon include graphite, such as amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite. Examples of amorphous carbon include soft carbon (low-temperature calcined carbon), hard carbon, mesophase pitch carbide, and calcined coke.

[0141] As the metal or an alloy of these metals and lithium, a metal containing one or more of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn, or an alloy of these metals and lithium can be used.

[0142] The metal composite oxide is PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), and Sn x Me 1-x Me’ y O z (Me: Mn, Fe, Pb, Ge; Me’: Al, B, P, Si, elements of Group 1, Group 2, Group 3 of the periodic table, halogen; 0<x≦1; 1≦y≦3; 1≦z≦8) may be one or more of them.

[0143] As the substance capable of doping and undoping lithium, Si, SiO x (0<x<2), Si-Y alloy (where Y is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (where Y is an element selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), etc. can be mentioned, and one or more of these may be mixed with SiO2 and used. The element Y may be selected from Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db (dubnium), Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0144] Examples of the transition metal oxide include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

[0145] The negative electrode active material may be included in an amount of 80 wt % to 99 wt % based on the total weight of the solid content in the negative electrode slurry.

[0146] The binder is a component that assists in bonding between the conductive material, active material, and current collector, and may be added in an amount of 1 wt% to 30 wt% based on the total weight of the solids in the negative electrode slurry. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene-butadiene rubber, fluororubber, and various copolymers thereof.

[0147] The conductive material is a component for further improving the conductivity of the negative electrode active material and may be added in an amount of 0.5 wt % to 20 wt % based on the total weight of the solids in the negative electrode slurry. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. Examples of conductive materials that can be used include carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; graphite powders such as natural graphite, artificial graphite, carbon nanotubes, and graphite, which have highly developed crystalline structures; conductive fibers such as carbon fibers and metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0148] The solvent for the negative electrode slurry may include water or an organic solvent such as N-methyl-2-pyrrolidone or alcohol, and may be used in an amount that provides a suitable viscosity when containing the negative electrode active material, binder, conductive material, etc. For example, the solvent may be included so that the solids concentration in the slurry containing the negative electrode active material, binder, and conductive material is 30 wt % to 80 wt %, preferably 40 wt % to 70 wt %.

[0149] 3) Separator The separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator that is commonly used as a separator in a lithium secondary battery can be used without any particular limitation. In particular, a separator that has low resistance to the movement of ions in the electrolyte, excellent electrolyte impregnation ability, and safety is preferred.

[0150] Specifically, the separator may be a 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; or a laminate structure of two or more layers thereof. Conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, may also be used. To ensure heat resistance or mechanical strength, a coated separator containing a ceramic component or a polymeric substance may also be used, and may be used in a single-layer or multi-layer structure.

[0151] The lithium secondary battery according to the present invention can be usefully used in portable devices such as mobile phones, notebook computers, and digital cameras; and electric vehicles such as hybrid electric vehicles (HEVs).

[0152] Therefore, according to another embodiment of 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.

[0153] The battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); and power storage systems.

[0154] 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.

[0155] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for small devices, but also as a unit battery in a medium- to large-sized battery module containing a large number of battery cells.

[0156] Hereinafter, the present invention will be described in detail with reference to examples. However, the examples of the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0157] Synthesis Example 1 <Preparation of Compound Represented by Chemical Formula 3-3> A flask was charged with 5 g of 3-butene-1,2-diol, 11.5 g of NaSO, and 10 g of water, and the mixture was stirred at 65°C for 9 hours while maintaining the pH at 7.3 to produce a reaction solution. The reaction solution was concentrated by distillation under reduced pressure, and 50 ml of methanol was added to obtain a precipitate. The precipitate was filtered under reduced pressure and dried in a vacuum oven to obtain 10 g of sodium 3,4-dihydroxybutane 2-sulfonate.

[0158] Then, 10 g of the sodium 3,4-dihydroxybutenesulfonate, 0.2 g of dimethylformamide, and 70 g of tetrahydroxyfuran were added to a flask, and 10 g of thionyl chloride was slowly added dropwise at 0°C. After the addition was completed, the reaction mixture was heated at 60°C for 2 hours, and then cooled to 25°C, and hydrochloric acid and methanol were added. The reaction mixture was then passed through a silica column and concentrated under reduced pressure to obtain 5 g of 3-hydroxymethyl-1,3-propane sultone.

[0159] Next, 30 g of diethyl acetate and 2.9 g of pyridine were added to the flask, and 5 g of 1-propyne-1-sulfonyl chloride was slowly added at 0°C and stirred at 25°C for 30 minutes. 5 g of the 3-hydroxymethyl-1,3-propane sultone was dissolved in 20 g of dimethyl acetate and slowly added to the flask. After reacting for 2 hours, the product was extracted as an organic layer using water and dimethyl acetate. The organic layer was concentrated to obtain the compound represented by chemical formula 3-3.

[0160] The synthesis of the compound represented by the chemical formula 3-3 was confirmed by 1H-NMR spectroscopy (Bruker, AVANCE NEO), and the 1H-NMR data is shown below. 1 H-NMR (500 MHz, Bruker, ACN-d3) = 4.8(1H), 4.18(1H), 4.05(1H), 3.30(2H), 2.55(1H), 2.3(1H), 1.9(3H)

[0161] Synthesis Example 2 <Preparation of Compound Represented by Chemical Formula 4-1> In the same manner as in Synthesis Example 1, 5 g of 1-propyne-1-sulfonyl chloride was obtained.

[0162] A flask was charged with 30 g of diethyl acetate and 2.9 g of pyridine, and 2.2 g of thionyl chloride was slowly added thereto, followed by stirring at 25°C for 30 minutes. 5 g of the 3-hydroxymethyl-1,3-propane sultone was dissolved in 20 g of dimethyl acetate and slowly added to the flask. After reacting for 2 hours, the product was extracted as an organic layer using water and methylene chloride. The organic layer was concentrated to obtain the compound represented by chemical formula 4-1.

[0163] The synthesis of the compound represented by the chemical formula 4-1 was confirmed by 1H-NMR spectroscopy (Bruker, AVANCE NEO), and the 1H-NMR data is shown below. 1 H-NMR (500 MHz, Bruker, ACN-d3) = 4.9(2H), 4.28(2H), 4.15(2H), 3.35(4H), 2.6(2H), 2.4(2H)

[0164] Synthesis Example 3 <Preparation of Compound Represented by Chemical Formula 4-3> A flask was charged with 5 g of the compound represented by formula 4-1 obtained in Synthesis Example 2, 40 g of acetonitrile, and 20 g of water. At 0°C, 0.03 g of RuCl3 and 4 g of NaIO4 were dissolved in 30 g of water to prepare a mixture. The mixture was then slowly added dropwise to the flask while stirring and allowed to react for 30 minutes. 100 g of t-butyl ether was then added to the flask and stirred, after which the product was separated. The product was extracted as an organic layer using water and ethyl acetate and concentrated under reduced pressure to obtain the compound represented by formula 4-3.

[0165] The synthesis of the compound represented by the chemical formula 4-3 was confirmed by 1H-NMR spectroscopy (Bruker, AVANCE NEO), and the 1H-NMR data is shown below. 1H-NMR (500 MHz, Bruker, ACN-d3) = 5.1(2H), 4.7(2H), 4.6(2H), 3.5(4H), 2.9(2H), 2.4(2H)

[0166] Example 1 <Production of non-aqueous electrolyte> Ethylene carbonate and ethyl methyl carbonate were mixed in a volume ratio of 3:7, and LiPF6 was dissolved therein to a concentration of 1.0 M to prepare a non-aqueous organic solution. 1.00 parts by weight of a compound represented by Chemical Formula 1-1-1 (manufacturer: TCI, trade name: Chromone-3-carbonitrile) was mixed with 99.00 parts by weight of the non-aqueous organic solution to prepare a non-aqueous electrolyte.

[0167] <Manufacturing lithium secondary batteries> N-methyl-2-pyrrolidone was used as the positive electrode active material ((0.35)Li2MnO3·(0.65)LiNi 0.55 Mn 0.45 A cathode slurry (solid content: 60.00 wt%) was prepared by adding 02), a conductive material (carbon black), and a binder (polyvinylidene fluoride) in a weight ratio of 95.5:1.5:3.0. The cathode slurry was applied to a 15.00 μm-thick aluminum (Al) thin film as a cathode current collector, dried, and then roll-pressed to prepare a cathode.

[0168] Anode active material (artificial graphite: natural graphite weight ratio = 1:1), conductive material (carbon black), and binder (polyvinylidene fluoride) were mixed in a weight ratio of 96.0:0.5:3.5 with distilled water as a solvent to prepare anode slurry (solid content: 50.00 wt%). The anode slurry was applied to an 8 μm-thick copper (Cu) thin film as anode current collector, dried, and then roll-pressed to prepare anode.

[0169] A separator (porous polypropylene) was placed between the positive and negative electrodes in a dry room to prepare an electrode assembly. The electrode assembly was placed in a battery case, and the nonaqueous electrolyte was poured into the battery case and sealed to prepare a pouch-type lithium secondary battery (battery capacity: 200 mA·h).

[0170] Example 2 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-2-2 (manufacturer: TCI, trade name: Chromone-2-carboxylic acid) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0171] Example 3 A nonaqueous electrolyte solution and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by Chemical Formula 1-3-1 (manufacturer: Aurum Pharmatech, trade name: 8-methyl-4H-chromen-4-one) was mixed in place of the compound represented by Chemical Formula 1-1-1 when the nonaqueous electrolyte solution of Example 1 was manufactured.

[0172] Example 4 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-4-1 (manufacturer: Sigma Aldrich, trade name: 7-Hydroxy-4-chromone) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0173] Example 5 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-5-1 (manufacturer: TCI, product name: 6-Nitrochromone) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0174] Example 6 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-6-2 (manufacturer: Sigma Aldrich, trade name: 5-Hydroxy-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the non-aqueous electrolyte solution of Example 1.

[0175] Example 7 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-7-1 (manufacturer: TCI, product name: 2-Amino-3-formylchromone) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0176] Example 8 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by chemical formula 1-8-1 (manufacturer: Sigma Aldrich, trade name: 8-Chloro-4-oxo-4H-chromene-3-carbaldehyde) was mixed in place of the compound represented by chemical formula 1-1-1 when manufacturing the non-aqueous electrolyte of Example 1.

[0177] Example 9 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-8-3 (manufacturer: Sigma Aldrich, trade name: 8-Methoxy-3-phenyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1 during the production of the non-aqueous electrolyte solution of Example 1.

[0178] Example 10 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-9-4 (manufacturer: Sigma Aldrich, trade name: 7-chloro-4-oxo-4H-chromene-3-carbonitrile) was mixed in place of the compound represented by chemical formula 1-1-1.

[0179] Example 11 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-9-14 (manufacturer: TCI, trade name: 7-Hydroxyisoflavone) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the non-aqueous electrolyte solution of Example 1.

[0180] Example 12 In the production of the non-aqueous electrolyte solution of Example 1, a compound represented by chemical formula 1-10-5 (manufacturer: Sigma Aldrich, trade name: 3-cyano-6-fluorochromone) was mixed in place of the compound represented by chemical formula 1-1-1. A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1.

[0181] Example 13 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-10-6 (manufacturer: TCI, trade name: 6-methylchromone-3-carbonitrile) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0182] Example 14 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by chemical formula 1-11-1 (manufacturer: Sigma Aldrich, trade name: 8-chloro-4-oxo-4H-chromene-3-carbaldehyde) was mixed instead of the compound represented by chemical formula 1-1-1 during the manufacture of the non-aqueous electrolyte of Example 1.

[0183] Example 15 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-12-1 (manufacturer: Sigma Aldrich, trade name: 7-Fluorochromone-2-carboxylic acid) was mixed in place of the compound represented by chemical formula 1-1-1 when producing the nonaqueous electrolyte solution of Example 1.

[0184] Example 16 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by chemical formula 1-13-2 (manufacturer: Sigma Aldrich, trade name: methyl 6-chloro-4-oxo-4H-chromene-2-carboxylate) was mixed in place of the compound represented by chemical formula 1-1-1 when manufacturing the non-aqueous electrolyte of Example 1.

[0185] Example 17 In the production of the non-aqueous electrolyte solution of Example 1, a compound represented by chemical formula 1-14-2 (manufacturer: Sigma Aldrich, trade name: 7-methoxy-2-methyl-3-phenyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1. A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-14-2 (manufacturer: Sigma Aldrich, trade name: 7-methoxy-2-methyl-3-phenyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1.

[0186] Example 18 A nonaqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that a compound represented by Chemical Formula 1-15-1 (manufacturer: SpectraBase, product name: 2-AMINO-6-FLUORO-4-OXO-4H-1-BENZOPYRAN-3-CARBOXALDEHYDE) was mixed in place of the compound represented by Chemical Formula 1-1-1 when the nonaqueous electrolyte of Example 1 was manufactured.

[0187] Example 19 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-16-1 (manufacturer: Sigma Aldrich, trade name: 7-Hydroxy-8-methyl-3-phenyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1.

[0188] Example 20 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-17-1 (manufacturer: Sigma Aldrich, trade name: 6,8-Dichloro-4-oxo-4H-chromene-3-carbaldehyde) was mixed in place of the compound represented by chemical formula 1-1-1 during the production of the non-aqueous electrolyte solution of Example 1.

[0189] Example 21 In the preparation of the non-aqueous electrolyte solution of Example 1, a compound represented by chemical formula 1-18-2 (manufacturer: Sigma Aldrich, trade name: 6-chloro-7-methyl-4-oxo-4H-chromene-3-carbonitrile) was mixed in place of the compound represented by chemical formula 1-1-1. A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by chemical formula 1-18-2 (manufacturer: Sigma Aldrich, trade name: 6-chloro-7-methyl-4-oxo-4H-chromene-3-carbonitrile) was mixed in place of the compound represented by chemical formula 1-1-1.

[0190] Example 22 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-19-1 (manufacturer: Sigma Aldrich, trade name: 6,8-Dichloro-4-oxo-4H-chromene-2-carboxylic acid) was mixed in place of the compound represented by chemical formula 1-1-1.

[0191] Example 23 In the production of the non-aqueous electrolyte solution of Example 1, instead of the compound represented by chemical formula 1-1-1, a compound represented by chemical formula 1-20-3 (manufacturer: Sigma Aldrich, trade name: 7-methoxy-2-8-dimethyl-3-phenyl-4H-chromen-4-one) was mixed. A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a non-aqueous electrolyte solution and a lithium secondary battery were produced.

[0192] Example 24 In the preparation of the non-aqueous electrolyte solution of Example 1, a compound represented by chemical formula 1-21-1 (manufacturer: Sigma Aldrich, trade name: 6,8-dichloro-3-ethyl-2-methyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1. A non-aqueous electrolyte solution and a lithium secondary battery were prepared in the same manner as in Example 1, except that a compound represented by chemical formula 1-21-1 (manufacturer: Sigma Aldrich, trade name: 6,8-dichloro-3-ethyl-2-methyl-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1.

[0193] Example 25 In the production of the non-aqueous electrolyte solution of Example 1, a compound represented by chemical formula 1-22-1 (manufacturer: Sigma Aldrich, trade name: 2,5-dimethyl-3-phenoy-7-propoxy-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1. A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that a compound represented by chemical formula 1-22-1 (manufacturer: Sigma Aldrich, trade name: 2,5-dimethyl-3-phenoy-7-propoxy-4H-chromen-4-one) was mixed in place of the compound represented by chemical formula 1-1-1.

[0194] Example 26 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, when producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of the compound represented by Chemical Formula 1-1-1 and 0.50 parts by weight of a compound represented by Chemical Formula 2-3 (manufacturer: Sigma Aldrich, trade name: 1,3-propane sultone) were mixed instead of 1.00 parts by weight of the compound represented by Chemical Formula 1-1-1.

[0195] Example 27 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, when producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of the compound represented by Chemical Formula 1-1-1 and 0.50 parts by weight of the compound represented by Chemical Formula 3-3 produced in Synthesis Example 1 were mixed instead of 1.00 parts by weight of the compound represented by Chemical Formula 1-1-1.

[0196] Example 28 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, when producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of the compound represented by Chemical Formula 1-1-1 and 0.50 parts by weight of the compound represented by Chemical Formula 4-3 produced in Synthesis Example 3 were mixed instead of 1.00 parts by weight of the compound represented by Chemical Formula 1-1-1.

[0197] Example 29 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, in producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of a compound represented by chemical formula 1-8-1 and 0.50 parts by weight of a compound represented by chemical formula 2-3 (manufacturer: Sigma Aldrich, trade name: 1,3-propane sultone) were mixed instead of 1.00 parts by weight of the compound represented by chemical formula 1-1-1.

[0198] Example 30 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, when producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of the compound represented by Chemical Formula 1-8-1 and 0.50 parts by weight of the compound represented by Chemical Formula 3-3 produced in Synthesis Example 1 were mixed instead of 1.00 parts by weight of the compound represented by Chemical Formula 1-1-1.

[0199] Example 31 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, in producing the nonaqueous electrolyte solution of Example 1, 0.50 parts by weight of the compound represented by Chemical Formula 1-8-1 and 0.50 parts by weight of the compound represented by Chemical Formula 4-3 produced in Synthesis Example 3 were mixed instead of 1.00 parts by weight of the compound represented by Chemical Formula 1-1-1.

[0200] Comparative Example 1 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1-1 was not mixed when producing the non-aqueous electrolyte solution of Example 1.

[0201] Comparative Example 2 A non-aqueous electrolyte and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 4H-chromon-4-one was mixed instead of the compound represented by Chemical Formula 1-1-1 when the non-aqueous electrolyte of Example 1 was manufactured.

[0202] Comparative Example 3 A non-aqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that 6-fluorochromone (Cas 105300-38-7) was mixed in place of the compound represented by Chemical Formula 1-1-1 during the production of the non-aqueous electrolyte solution of Example 1.

[0203] Comparative Example 4 A non-aqueous electrolyte solution and a lithium secondary battery were manufactured in the same manner as in Example 1, except that 2-phenyl-4H-chromon-4-one (Cas 525-82-6) was mixed in place of the compound represented by Chemical Formula 1-1-1 during the manufacture of the non-aqueous electrolyte solution of Example 1.

[0204] Comparative Example 5 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1-1 was not mixed and 1.00 parts by weight of the compound represented by Chemical Formula 2-3 was mixed during the production of the nonaqueous electrolyte solution of Example 26.

[0205] Comparative Example 6 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that, when producing the nonaqueous electrolyte solution of Example 26, the compound represented by Chemical Formula 1-1-1 was not mixed, and 1.00 parts by weight of the compound represented by Chemical Formula 3-3 was mixed.

[0206] Comparative Example 7 A nonaqueous electrolyte solution and a lithium secondary battery were produced in the same manner as in Example 1, except that the compound represented by Chemical Formula 1-1-1 was not mixed and 1.00 parts by weight of the compound represented by Chemical Formula 4-3 was mixed during the production of the nonaqueous electrolyte solution of Example 26.

[0207] Experimental Example 1: Evaluation of the amount of gas generated during activation The initial volume (hereinafter referred to as "initial volume (1)") of each of the lithium secondary batteries manufactured in the Examples and Comparative Examples was measured. Specifically, the initial volume (1) was measured using a Two-pls TWD-150DM device at 25°C by placing the lithium secondary battery in a bowl filled with water, based on Archimedes' law.

[0208] The lithium secondary battery was activated by charging at a constant current of 0.1 C to 4.60 V under constant current-constant voltage (CC-CV) charging conditions using a PESCO05-0.5 charger / discharger (manufacturer: PNE Solution Co., Ltd., 5 V, 500 mA) at 45°C, followed by discharging to 2.50 V under CC conditions with a 0.05 C current cut-off. Thereafter, the lithium secondary battery was placed in a bowl filled with water at 25°C using Two-pls TWD-150DM equipment, and the volume after activation (hereinafter referred to as the "activated volume") was measured.

[0209] The measured initial volume (1) and activation volume were substituted into the following formula to calculate the amount of gas (ml, hereinafter referred to as "gas amount") generated during activation per 1 g of positive electrode active material, and the results are shown in Table 1 below.

[0210] Amount of gas generated during activation per 1 g of positive electrode active material (ml / g) = {(Activation volume (ml)) - (Initial volume (1) (ml))} / (Weight of positive electrode active material (g))

[0211] Experimental example 2: Evaluation of life characteristics Each lithium secondary battery prepared in the Examples and Comparative Examples was charged at a constant current of 0.1 C to 4.60 V under constant current-constant voltage (CC-CV) charging conditions using a PESC05-0.5 charger / discharger (manufacturer: PEN Solutions, 5 V, 500 mA) at 45°C. Then, with a current cutoff of 0.05 C, it was discharged at 0.33 C to 2.50 V under CC conditions. This charge / discharge cycle constitutes one cycle, and two cycles were performed. Next, the battery was fully charged at a constant current-constant voltage of 0.33 C / 4.35 V, adjusted to an SOC of 50%, and then discharged at 2.5 C for 30 seconds. The initial resistance was calculated based on the difference between the voltage before discharge and the voltage after 10 seconds of discharge. It was then discharged at a constant current of 0.33 C to 2.50 V.

[0212] The battery was then degassed and placed in a bowl filled with water at 25°C using a Two-Pls TWOD-150DM device to measure its initial volume (hereinafter referred to as "initial volume (2)"). The battery was then charged at a constant current of 0.33 C to 4.35 V under CC-CV charging conditions at 45°C, followed by a 0.05 C current cutoff and 20 minutes of storage. The battery was then discharged at 0.33 C to 2.50 V under CC conditions. This cycle constitutes one charge / discharge cycle, and 100 cycles were performed. The discharge capacity after the first cycle (hereinafter referred to as "initial discharge capacity") and the discharge capacity after the 100th cycle were measured using a PESC05-0.5 charger / discharger (manufactured by PEN Solutions, 5 V, 500 mA). The discharge capacity retention rate after 100 cycles was calculated using the following equation (1). The results are shown in Table 1.

[0213] <Expression 1> Discharge capacity retention rate after 100 cycles (%) = {(discharge capacity after 100 cycles) / (initial discharge capacity)} × 100

[0214] Then, using a Two-pls TWD-150DM device, the lithium secondary battery was placed in a bowl filled with water at 25°C, and the volume after 100 charge / discharge cycles (volume after 100 cycles) was substituted into the following equation 2 to calculate the volume change rate, and the results are shown in Table 1 below.

[0215] <Expression 2> Volume change rate after 100 cycles (%) = [{(volume after 100 cycles) - (initial volume (2))} / (initial volume (2))] × 100

[0216] After 100 cycles, the battery was discharged at 2.5 C with an SOC of 50%, and the resistance after 100 cycles was calculated from the difference between the discharge voltage and the voltage after 10 seconds of discharge. The initial resistance calculated above and the resistance after 100 cycles were substituted into Equation 3 below to calculate the resistance increase rate after 100 cycles, and the results are shown in Table 1 below.

[0217] <Expression 3> Resistance increase rate after 100 cycles (%) = [{(resistance after 100 cycles) - (initial resistance)} / (initial resistance)] × 100

[0218] [Table 1A] [Table 1B]

[0219] Referring to Table 1, Examples 1 to 25, which used the compound represented by Chemical Formula 1 as an additive, showed significantly less gas generation during activation, a higher discharge capacity retention rate after 100 cycles, a lower resistance increase rate after 100 cycles, and a smaller volume change rate after 100 cycles, compared to Comparative Example 1, which did not use an additive. Furthermore, Examples 1 to 25 showed significantly less gas generation during activation, a higher discharge capacity retention rate after 100 cycles, a lower resistance increase rate after 100 cycles, and a smaller volume change rate after 100 cycles, compared to Comparative Example 2, which used 4-H-chromon-4-one as an additive.

[0220] Furthermore, compared to Comparative Example 3, which used 6-fluorochromone as an additive, Examples 1 to 25 had significantly less gas generated during activation, a higher discharge capacity retention rate after 100 cycles, a lower resistance increase rate after 100 cycles, and a smaller volume change rate after 100 cycles.

[0221] Furthermore, compared to Comparative Example 4, which used 2-phenyl-4H-chromon-4-one as the additive, Examples 1 to 25 had significantly less gas generated during activation, a higher discharge capacity retention rate after 100 cycles, a lower resistance increase rate after 100 cycles, and a smaller volume change rate after 100 cycles.

[0222] Furthermore, in Examples 26 and 29, in which the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 were used as additives, the amount of gas generated during activation was significantly smaller, the discharge capacity retention rate after 100 cycles was higher, the resistance increase rate after 100 cycles was lower, and the volume change rate after 100 cycles was smaller, compared to Comparative Example 5, in which no compound represented by Chemical Formula 1 was used at all and the compound represented by Chemical Formula 2 was used as an additive.

[0223] Furthermore, in Examples 27 and 30, in which the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 3 were used as additives, the amount of gas generated during activation was significantly smaller, the discharge capacity retention rate after 100 cycles was higher, the resistance increase rate after 100 cycles was lower, and the volume change rate after 100 cycles was smaller, compared to Comparative Example 6, in which no compound represented by Chemical Formula 1 was used at all and the compound represented by Chemical Formula 3 was used as an additive.

[0224] Furthermore, in Examples 28 and 31, in which the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 3 were used as additives, the amount of gas generated during activation was significantly smaller, the discharge capacity retention rate after 100 cycles was higher, the resistance increase rate after 100 cycles was lower, and the volume change rate after 100 cycles was smaller, compared to Comparative Example 7, in which no compound represented by Chemical Formula 1 was used at all and the compound represented by Chemical Formula 4 was used as an additive.

Claims

1. A non-aqueous electrolyte solution for a lithium secondary battery, comprising a first additive containing a compound represented by the following chemical formula 1: 【Chemistry 1】 (In the above Chemical Formula 1, R １ , R ３ ~R ６ may be the same or different, and are each independently hydrogen, halogen, *-L １ -C≡N, *-L ２ -C(=O)R ７ , *-L ３ -NR ８ R ９ , *-L ４ -OR １０ , C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula R ２ is hydrogen, halogen, *-L ５ -C≡N, *-L ６ -C(=O)R １１ , *-L ７ -NR １２ R １３ , *-L ８ -OR １４ , C １ ~C ２０ or an alkyl group of C ２ ~C ２０ is an alkynyl group of the formula R ７ ~R １４ may be the same or different, and are independently hydrogen, oxygen, *-L ９ -OR １５ , C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula R １５ is hydrogen, C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula L １ ~L ９ may be the same or different, and are each independently a direct bond or C １ ~C １０ is an alkylene group, R １ ~R ６ Isn't it hydrogen at the same time? １ ~R ６ At least one of R is halogen; １ ~R ６ The remaining five of these are not hydrogen at the same time.)

2. The nonaqueous electrolyte solution for a lithium secondary battery according to claim 1, wherein the compound represented by Chemical Formula 1 includes one or more compounds represented by the following Chemical Formulas 1-1 to 1-22: 【Chemistry 2】 【Transformation 3】 (In the above chemical formulas 1-1 to 1-22, R １ ', R ３ '~R ６ ' may be the same or different, and each independently represents a halogen, *-L １ '-C≡N, *-L ２ '-C(=O)R ７ ', *-L ３ '-NR ８ 'R ９ ', *-L ４ '-OR １０ ', C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula R ２ ' is halogen, *-L ５ '-C≡N, *-L ６ '-C(=O)R １１ ', *-L ７ '-NR １２ 'R １３ ', *-L ８ '-OR １４ ', C １ ~C ２０ or an alkyl group of C ２ ~C ２０ is an alkynyl group of the formula R ７ '~R １４ ' may be the same or different, and are independently hydrogen, oxygen, *-L ９ '-OR １５ ', C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula R １５ ' is hydrogen, C １ ~C ２０ alkyl group of C ２ ~C ２０ an alkynyl group of C ６ ~C ２０ is an aryl group of the formula L １ '~L ９ ' may be the same or different, and are each independently a direct bond or C １ ~C １０ is an alkylene group of the formula:

3. The nonaqueous electrolyte solution for a lithium secondary battery according to claim 1 , wherein the compound represented by Chemical Formula 1 includes at least one compound represented by the following chemical formula: 【Chemistry 4】 【Transformation 5】 【Transformation 6】 【Transformation 7】 【Transformation 8】 【Chemistry 9】 【Chemistry 10】

4. 2. The non-aqueous electrolyte solution for a lithium secondary battery according to claim 1, wherein the content of the compound represented by Formula 1 is 0.01 to 10.00 parts by weight based on 100 parts by weight of the non-aqueous electrolyte solution for a lithium secondary battery.

5. The nonaqueous electrolyte solution for a lithium secondary battery according to claim 1, further comprising a second additive containing one or more compounds represented by the following chemical formulas 2 to 4: 【Chemistry 11】 (In the above chemical formula 2, X ２１ is *-S(=O)-* or *-S(=O) ２ -*, X ２２ and X ２３ may be the same or different, and each independently represents a direct bond, *-O-*, or C １ ~C １０ is an alkylene group of the formula: 【Chemistry 12】 In the above Chemical Formula 3, Y ３１ and L ３３ may be the same or different, and each independently represents *-S(=O)-* or *-S(=O) ２ -*, Y ３２ , Y ３３ , L ３１ , L ３２ , L ３４ , and L ３５ may be the same or different, and each independently represents a direct bond, *-O-*, or C １ ~C １０ is an alkylene group of the formula R ３１ is hydrogen, C １ ~C １０ alkyl group of C ２ ~C １０ or an alkenylene group of C ２ ~C １０ is an alkynylene group of the formula: 【Chemistry 13】 In the above Chemical Formula 4, Z ４２ , Z ４５ , and L ４３ may be the same or different, and each independently represents *-S(=O)-* or *-S(=O) ２ -*, Z ４１ , Z ４３ , Z ４４ , Z ４６ , L ４１ , L ４２ , L ４４ , and L ４５ may be the same or different, and each independently represents a direct bond, *-O-*, or C １ ~C １０ is an alkylene group of the formula:

6. The compound represented by Chemical Formula 2 includes one or more compounds represented by the following Chemical Formulas 2-1 to 2-4: The compound represented by Chemical Formula 3 includes one or more compounds represented by the following Chemical Formulas 3-1 to 3-3: The nonaqueous electrolyte solution for a lithium secondary battery according to claim 5, wherein the compound represented by Chemical Formula 4 includes one or more compounds represented by the following Chemical Formulas 4-1 to 4-3: 【Chemistry 14】

7. 6. The non-aqueous electrolyte solution for a lithium secondary battery according to claim 5, wherein the content of the second additive is 0.01 to 5.00 parts by weight based on 100 parts by weight of the non-aqueous electrolyte solution for a lithium secondary battery.

8. 2. The nonaqueous electrolyte solution for a lithium secondary battery according to claim 1, wherein the nonaqueous electrolyte solution for a lithium secondary battery contains at least one of a lithium salt and an organic solvent.

9. The nonaqueous electrolyte solution for a lithium secondary battery according to any one of claims 1 to 8, 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.

10. 10. The lithium secondary battery of claim 9, wherein the positive electrode active material comprises at least one of an over-lithiated layered oxide represented by the following Chemical Formula 5 and an NCM-based lithium transition metal composite oxide represented by the following Chemical Formula 6: <Chemical formula 5> 8Li ２ MnO ３ ・(1-8)- ａ１ Ni ｂ１ Co ｃ１ Mn ｄ１ M １ ｅ１ O ２ (In the above chemical formula 5, 0<x<1, 0≦a1≦2, 0≦b1≦1, 0≦c1≦1, 0≦d1≦1, 0≦e1≦1, a1+b1+c1+d1+e1=2, M １ may include one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc. <Chemical formula 6> Li ａ２ Ni ｂ２ Co ｃ２ Mn ｄ２ M ２ ｅ２ O ２ In the above Chemical Formula 6, 0.9≦a2≦1.1, 0.7≦b2<1, 0≦c2<1, 0<d2<1, 0≦e2<1, b2+c2+d2+e2=1, M ２ may contain one or more of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, Ta, Mo, Sc, V, Zn, Cu, In, S, Bi, Rh, Pd, Ag, Cd, and Tc.

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