Electrolyte for lithium secondary battery and lithium secondary battery containing the same

Abstract

The present invention provides an electrolyte for a lithium secondary battery, the electrolyte comprising a non-aqueous organic solvent, a lithium salt, and an additive, the additive being a composition comprising a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and a lithium secondary battery comprising the electrolyte. The details of Chemical Formulas 1 and 2 are as described in the specification. JPEG2024503911000032.jpg94170

Description

[Technical Field]

[0001] This description relates to an electrolyte for a lithium secondary battery and a lithium secondary battery containing the same. [Background technology]

[0002] Lithium secondary batteries are rechargeable and have an energy density per unit weight that is more than three times higher than conventional lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries, and they can be charged quickly. As a result, they have been commercialized for use in laptops, mobile phones, power tools, and electric bicycles, and research and development is actively underway to further improve their energy density.

[0003] Such a lithium secondary battery is used by injecting an electrolyte into a battery cell including a positive electrode including a positive electrode active material capable of lithium intercalation and deintercalation, and a negative electrode including a negative electrode active material capable of lithium intercalation and deintercalation.

[0004] In particular, the electrolyte uses an organic solvent in which a lithium salt is dissolved, and such an electrolyte is important in determining the stability and performance of the lithium secondary battery.

[0005] Recently, safety issues have arisen due to the increase in energy density resulting from the increase in capacity of lithium secondary batteries, and one method known to improve safety is to use a flame retardant as an additive to the electrolyte.

[0006] As the flame retardant, fluorine-based compounds, phosphorus-based compounds, sulfur-based compounds, etc. are mainly used as compounds that have flame retardancy and cause little environmental pollution, but the use of these flame retardants can sometimes lead to a decrease in battery performance.

[0007] Therefore, there is a demand for electrolytes that improve battery performance while ensuring safety. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of one embodiment is to provide an electrolyte for a lithium secondary battery that ensures battery safety, such as thermal safety and penetration safety, while at the same time improving high-temperature storage characteristics.

[0009] Another object of another embodiment is to provide a lithium secondary battery having improved high-temperature storage characteristics by applying the electrolyte solution, thereby improving high-temperature safety, particularly by reducing the amount of gas generation during high-temperature storage and lowering the rate of increase in resistance. [Means for solving the problem]

[0010] One embodiment of the present invention provides an electrolyte solution for a lithium secondary battery, the electrolyte solution comprising a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive comprises a first compound represented by the following Chemical Formula 1 and a second compound represented by the following Chemical Formula 2: [ka] In the above Chemical Formula 1 and Chemical Formula 2, R 1 ~R 6 are each independently hydrogen, halogen, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C1-C10 alkylamine group; X 1 ~X 3 are each independently a halogen group or -OL a -R a and X 1 ~X 3 At least one of the groups is -OL a -R a and L a are each independently a single bond or a substituted or unsubstituted C1-C10 alkylene group, R aare each independently a cyano group (-CN), a difluorophosphate group (-OPF2), a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; R a exist independently of each other, or At least two R a are linked to form a substituted or unsubstituted monocyclic or polycyclic aliphatic heterocycle, or a substituted or unsubstituted monocyclic or polycyclic aromatic heterocycle.

[0011] The composition may contain the first compound and the second compound in a weight ratio of 0.5:1 to 10:1.

[0012] The composition may contain the first compound and the second compound in a weight ratio of 5:1 to 10:1.

[0013] R of Formula 1 1 ~R 6 At least one of the groups may be a fluoro group (—F).

[0014] R of Formula 1 1 ~R 6 at least one of which is a fluoro group (—F); Remaining R 1 ~R 6 At least one of the groups may be a substituted or unsubstituted C1 to C10 alkoxy group or a substituted or unsubstituted C1 to C10 alkylamine group.

[0015] The first compound is represented by Chemical Formula 1, which may be represented by Chemical Formula 1A or 1B below. [ka]

[0016] In the above Formula 1A and Formula 1B, R 7 ~R 9 are each independently a substituted or unsubstituted C1 to C10 alkyl group.

[0017] The first compound may be selected from the compounds listed in Group 1 below. [ka]

[0018] The second compound is represented by Chemical Formula 2, The formula 2 can be represented by any one of the following formulas 2-1 to 2-3. [ka] In the above chemical formula 2-1, m is an integer from 1 to 5; R 10 is a cyano group (-CN) or a difluorophosphate group (-OPF2); [ka] In the above chemical formula 2-2, L a1 ~L a3 are each independently a single bond or a substituted or unsubstituted C1-C5 alkylene group, R a1 ~R a3 are each independently a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; [ka] In the above chemical formula 2-3, X 1 is a halogen group or -OL a4 -R a4 and L a4 is a single bond or a substituted or unsubstituted C1-C5 alkylene group, R a4 is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; L 1 is a substituted or unsubstituted C2 to C5 alkylene group.

[0019] The second compound may be any one selected from the compounds listed in Group 2 below. [ka]

[0020] The first compound may be included in an amount of 0.1 wt % to 5.0 wt % based on the total weight of the electrolyte solution for a lithium secondary battery.

[0021] The second compound may be included in an amount of 0.1 wt % to 5.0 wt % based on the total weight of the electrolyte solution for a lithium secondary battery.

[0022] The composition may be included in an amount of 1.0 wt % to 10 wt % based on the total weight of the electrolyte solution for lithium secondary batteries.

[0023] Another embodiment of the present invention provides a lithium secondary battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and the above-described electrolyte for a lithium secondary battery. [Effects of the Invention]

[0024] By applying an additive with improved thermal safety, it is possible to suppress the increase in internal resistance and gas generation of the battery after high-temperature storage, and to suppress the voltage drop, thereby realizing a lithium secondary battery with improved high-temperature storage characteristics. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic diagram illustrating a lithium secondary battery according to an embodiment of the present invention. [Figure 2] 1 is a graph showing the measurement of the activation time of a Current Interrupt Device (CID) of lithium secondary batteries according to Examples 1 to 11 and Comparative Examples 1 to 7. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, a lithium secondary battery according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, which are given by way of example only and are not intended to limit the scope of the present invention, which is defined only by the scope of the claims that follow.

[0027] Unless otherwise defined, the term "substituted" used herein means that at least one hydrogen atom in a substituent or compound has been replaced with deuterium, a halogen group, a hydroxyl group, an amino group, a substituted or unsubstituted C1-C30 amine group, a nitro group, a substituted or unsubstituted C1-C40 silyl group, a C1-C30 alkyl group, a C1-C10 alkylsilyl group, a C6-C30 arylsilyl group, a C3-C30 cycloalkyl group, a C3-C30 heterocycloalkyl group, a C6-C30 aryl group, a C2-C30 heteroaryl group, a C1-C20 alkoxy group, a C1-C10 fluoroalkyl group, a cyano group, or a combination thereof.

[0028] In one embodiment of the present invention, "substituted" means that at least one hydrogen atom in a substituent or compound is replaced with deuterium, a halogen group, a C1-C30 alkyl group, a C1-C10 alkylsilyl group, a C6-C30 arylsilyl group, a C3-C30 cycloalkyl group, a C3-C30 heterocycloalkyl group, a C6-C30 aryl group, a C2-C30 heteroaryl group, a C1-C10 fluoroalkyl group, or a cyano group. In another specific embodiment of the present invention, "substituted" means that at least one hydrogen atom in a substituent or compound is replaced with deuterium, a halogen group, a C1-C20 alkyl group, a C6-C30 aryl group, a C1-C10 fluoroalkyl group, or a cyano group. In another specific embodiment of the present invention, "substituted" means that at least one hydrogen atom in a substituent or compound is replaced with deuterium, a halogen group, a C1-C5 alkyl group, a C6-C18 aryl group, a C1-C5 fluoroalkyl group, or a cyano group. In addition, in a specific example of the present invention, "substituted" means that at least one hydrogen atom of a substituent or compound is substituted with deuterium, a cyano group, a halogen group, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a biphenyl group, a terphenyl group, a trifluoromethyl group, or a naphthyl group.

[0029] Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries, and lithium polymer batteries depending on the type of separator and electrolyte used, into cylindrical, prismatic, coin, pouch, and other types depending on the shape, and into bulk and thin film types depending on the size. The structures and manufacturing methods of these batteries are widely known in the art, so detailed description will be omitted.

[0030] Here, a cylindrical lithium secondary battery will be described as an example of a lithium secondary battery. Figure 1 illustrates a schematic structure of a lithium secondary battery according to an embodiment. Referring to Figure 1, a lithium secondary battery 100 according to an embodiment includes a battery cell including a positive electrode 114, a negative electrode 112 facing the positive electrode 114, a separator 113 disposed between the positive electrode 114 and the negative electrode 112, and an electrolyte (not shown) impregnating the positive electrode 114, the negative electrode 112, and the separator 113; a battery container 120 housing the battery cell; and a sealing member 140 sealing the battery container 120.

[0031] The configuration of the lithium secondary battery 100 according to one embodiment of the present invention will be described in more detail below.

[0032] A lithium secondary battery according to one embodiment of the present invention includes an electrolyte, a positive electrode, and a negative electrode.

[0033] The electrolyte solution includes a non-aqueous organic solvent, a lithium salt, and an additive, and the additive includes a composition including a first compound represented by the following Chemical Formula 1 and a second compound represented by the following Chemical Formula 2: [ka] In the above Chemical Formula 1 and Chemical Formula 2, R 1 ~R 6 are each independently hydrogen, halogen, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, or a substituted or unsubstituted C1-C10 alkylamine group; X 1 ~X 3 are each independently a halogen group or -OL a -R a and X 1 ~X 3 At least one of the groups is -OL a -R a and L aare each independently a single bond or a substituted or unsubstituted C1-C10 alkylene group, R a are each independently a cyano group (-CN), a difluorophosphate group (-OPF2), a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; R a exist independently of each other, or At least two R a are linked to form a substituted or unsubstituted monocyclic or polycyclic aliphatic heterocycle, or a substituted or unsubstituted monocyclic or polycyclic aromatic heterocycle.

[0034] The first compound is a phosphazene-based compound. When a fire occurs, oxygen is generated due to the breakdown of the electrolyte or the positive electrode active material. The first compound captures this oxygen to prevent combustion. It also captures radical products, terminating the radical chain reaction and suppressing side reactions within the battery. The first compound also acts as a coating decomposition additive, forming a coating with low resistance.

[0035] That is, the composition contains the first compound represented by Chemical Formula 1, thereby improving the high temperature safety of the battery.

[0036] The second compound is reductively decomposed to form a solid electrolyte interface (SEI) film on the negative electrode, thereby preventing the decomposition of the electrolyte and the resulting decomposition reaction of the electrode, thereby suppressing an increase in internal resistance due to gas generation.

[0037] In addition, by including the second compound, not only the flame retardant properties but also the high-temperature decomposition effect of the electrolyte can be suppressed by stabilizing the lithium salt in the electrolyte, thereby further improving the effect of suppressing gas generation inside the battery at high temperatures, thereby simultaneously improving the safety and life characteristics of the battery.

[0038] When the first compound and the second compound are used in combination, the combination not only provides flame retardancy but also stabilizes the lithium salt in the electrolyte, thereby suppressing side reactions in the electrolyte, thereby improving the high temperature stability of the battery.

[0039] As an example, the composition may contain the first compound and the second compound in a weight ratio of 0.5:1 to 10:1.

[0040] As a specific example, the composition may contain the first compound and the second compound in a weight ratio of 1:1 to 10:1, 2:1 to 10:1, or 3:1 to 10:1.

[0041] As a most specific example, the composition may contain the first compound and the second compound in a weight ratio of 5:1 to 10:1.

[0042] As an example, R 1 ~R 6 At least one of the groups may be a fluoro group (—F).

[0043] As a specific example, R 1 ~R 6 at least one of which is a fluoro group (—F); Remaining R 1 ~R 6 At least one of the groups may be a substituted or unsubstituted C1 to C10 alkoxy group or a substituted or unsubstituted C1 to C10 alkylamine group.

[0044] As a more specific example, the first compound is represented by Chemical Formula 1, and Chemical Formula 1 may be represented by the following Chemical Formula 1A or Chemical Formula 1B. [ka] In the above Formula 1A and Formula 1B, R 7 ~R 9 are each independently a substituted or unsubstituted C1 to C10 alkyl group.

[0045] For example, the first compound may be selected from the compounds listed in Group 1 below. [ka]

[0046] As an example, the second compound is represented by the formula 2: The formula 2 can be represented by any one of the following formulas 2-1 to 2-3. [ka] In the above chemical formula 2-1, m is an integer from 1 to 5; R 10 is a cyano group (-CN) or a difluorophosphate group (-OPF2); [ka] In the above chemical formula 2-2, L a1 ~L a3 are each independently a single bond or a substituted or unsubstituted C1-C5 alkylene group, R a1 ~R a3 are each independently a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; [ka] In the above chemical formula 2-3, X 1 is a halogen group or -OL a4 -R a4 and L a4 is a single bond or a substituted or unsubstituted C1-C5 alkylene group, R a4 is a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted C2 to C10 alkynyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, a substituted or unsubstituted C3 to C10 cycloalkenyl group, a substituted or unsubstituted C3 to C10 cycloalkynyl group, or a substituted or unsubstituted C6 to C20 aryl group; L 1 is a substituted or unsubstituted C2 to C5 alkylene group.

[0047] As a specific example, the second compound may be represented by Formula 2-1 or Formula 2-3.

[0048] For example, the second compound may be any one selected from the compounds listed in Group 2 below. [ka]

[0049] According to a most specific embodiment, the additive contained in the electrolyte for a lithium secondary battery according to the present invention may be a composition including at least one of the compounds listed in Group 1 as a first compound and at least one of the compounds listed in Group 2 as a second compound.

[0050] For example, the additive contained in the electrolyte for a lithium secondary battery according to the present invention may be a composition containing compound 1-a or compound 1-b of Group 1 as a first compound and compound 2-a or compound 2-d of Group 2 as a second compound.

[0051] In one example, the first compound and the second compound may be included in a weight ratio of about 0.5:1, about 1:1, about 2:1, about 3:1, about 5:1, or about 10:1.

[0052] Meanwhile, the first compound may be included in an amount of about 0.1 wt % to about 5.0 wt % based on the total weight of the electrolyte solution for lithium secondary batteries.

[0053] For example, the first compound may be contained in an amount of about 0.2% to about 5.0% by weight, such as about 0.25%, about 0.5%, about 1.0%, about 1.5%, about 2.5%, or about 5.0% by weight.

[0054] The second compound may be contained in an amount of about 0.1 wt % to about 5.0 wt % based on the total weight of the electrolyte solution for lithium secondary batteries.

[0055] For example, the second compound may be contained in an amount of about 0.2% by weight to about 5.0% by weight, about 0.3% by weight to about 5.0% by weight, about 0.4% by weight to about 5.0% by weight, or about 0.5% by weight to about 5.0% by weight, for example, about 0.5% by weight, about 1.0% by weight, about 2.5% by weight, or about 5.0% by weight.

[0056] The composition including the first compound and the second compound may be included in an amount of about 1.0 wt % to about 10 wt % based on the total weight of the electrolyte solution for a lithium secondary battery.

[0057] For example, the composition including the first compound and the second compound may be included in an amount of about 0.75 wt %, about 1.0 wt %, about 1.5 wt %, about 2.0 wt %, about 3.0 wt %, about 5.5 wt %, about 6.0 wt %, about 7.5 wt %, or about 10 wt % based on the total weight of the electrolyte for a lithium secondary battery.

[0058] When the content of the composition and the content of each component in the composition, i.e., the first compound and the second compound, are within the above ranges, a lithium secondary battery can be realized that has improved thermal safety, suppresses gas generation inside the battery, and improves battery characteristics at room temperature and high temperature.

[0059] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can migrate.

[0060] The non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, or aprotic solvent.

[0061] Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of the ester solvent include methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanolide, mevalonolactone, and caprolactone. Examples of the ether solvent include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. The ketone solvent may be cyclohexanone, etc. The alcohol solvent may be ethyl alcohol, isopropyl alcohol, etc. The aprotic solvent may be R 18 -CN(R 18(wherein R is a hydrocarbon group having 2 to 20 carbon atoms and having a linear, branched, or cyclic structure, and may contain a double bond, aromatic ring, or ether bond), nitriles such as dimethylformamide, amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, sulfolanes, etc. can be used.

[0062] The non-aqueous organic solvents may be used alone or in combination of two or more thereof. When two or more thereof are used in combination, the mixing ratio may be appropriately adjusted depending on the desired battery performance, which is well understood by those skilled in the art.

[0063] In addition, in the case of the carbonate-based solvent, it is preferable to use a mixture of cyclic carbonate and chain carbonate in a volume ratio of 1:9 to 9:1, thereby obtaining excellent electrolyte performance.

[0064] In particular, in one embodiment of the present invention, the non-aqueous organic solvent may contain the cyclic carbonate and the chain carbonate in a volume ratio of 2:8 to 5:5, and as a specific example, the cyclic carbonate and the chain carbonate may be contained in a volume ratio of 2:8 to 4:6.

[0065] As a more specific example, the cyclic carbonate and the chain carbonate may be contained in a volume ratio of 2:8 to 3:7.

[0066] The non-aqueous organic solvent may further include an aromatic hydrocarbon-based organic solvent in addition to the carbonate-based solvent, and the carbonate-based solvent and the aromatic hydrocarbon-based solvent may be mixed in a volume ratio of 1:1 to 30:1.

[0067] The aromatic hydrocarbon solvent may be an aromatic hydrocarbon compound represented by the following formula 3: [ka] In the above formula 3, R 11 ~R 16 are the same or different and are selected from the group consisting of hydrogen, halogen, alkyl groups having 1 to 10 carbon atoms, haloalkyl groups, and combinations thereof.

[0068] Specific examples of the aromatic hydrocarbon solvent include benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, fluorobenzene, fluoroisopropyl ether ... and combinations thereof.

[0069] The electrolyte may further include a vinylene carbonate-based compound, a vinylethylene carbonate-based compound, or an ethylene carbonate-based compound of the following Formula 4 as a life-enhancing additive to improve battery life. [ka] In the above formula 4, R 17 and R 18are the same or different and are selected from the group consisting of hydrogen, a halogen group, a cyano group (CN), a nitro group (NO), and a fluorinated alkyl group having 1 to 5 carbon atoms; 17 and R 18 At least one of R is selected from the group consisting of a halogen group, a cyano group (CN), a nitro group (NO2), and a fluorinated alkyl group having 1 to 5 carbon atoms, with the proviso that R 17 and R 18 But at the same time it is not hydrogen.

[0070] Representative examples of the ethylene carbonate compound include difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, fluoroethylene carbonate, etc. When such a life-improving additive is further used, the amount used can be appropriately adjusted.

[0071] The lithium salt is a substance dissolved in a non-aqueous organic solvent and serves as a lithium ion source in the battery, enabling basic lithium secondary battery operation and promoting the movement of lithium ions between the positive electrode and the negative electrode. Representative examples of such lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI)), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1The lithium salt may be one or more selected from the group consisting of lithium ions, such as fluorine, iodine, ...

[0072] The positive electrode includes a positive electrode current collector and a positive electrode active material layer located on the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0073] As the positive electrode active material, a compound capable of reversibly inserting and extracting lithium (lithiated insertion compound) can be used.

[0074] Specifically, at least one of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0075] Of course, the composite oxide may have a coating layer on its surface, or the composite oxide may be mixed with a composite oxide having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of oxides of the coating elements, hydroxides of the coating elements, oxyhydroxides of the coating elements, oxycarbonates of the coating elements, and hydroxycarbonates of the coating elements. The compounds forming the coating layer may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer formation process may be performed using any coating method (e.g., spray coating, dipping, etc.) that does not adversely affect the physical properties of the positive electrode active material, as this is well understood by those skilled in the art and will not be described in detail.

[0076] The positive electrode active material may be, for example, one or more lithium composite oxides represented by the following chemical formula 5.

[0077] [Chemical formula 5] Li x M 1 1-y-z M 2 y M 3 z O2 In the above Chemical Formula 5, 0.5≦x≦1.8, 0≦y<1, 0≦z<1, 0≦y+z<1, M 1 , M 2 and M 3 may each independently be any one selected from metals such as Ni, Co, Mn, Al, Sr, Mg, or La, and combinations thereof.

[0078] In one embodiment, the M 1It may be a metal such as Co, Mn, Al, Sr, Mg or La, and the M 2 and M 3 may each independently be Ni or Co.

[0079] In a specific embodiment, the M 1 may be Mn or Al, and the M 2 and M 3 may each independently be Ni or Co, but is not limited thereto.

[0080] In a more specific embodiment, the positive electrode active material may be a lithium composite oxide represented by any one of the following Chemical Formulas 5-1 to 5-3.

[0081] [Chemical Formula 5-1] Li x1 Ni y1 Co z1 Al 1-y1-z1 O2 In Chemical Formula 5-1, 1 ≦ x1 ≦ 1.2, 0 < y1 < 1, and 0 < z1 < 1.

[0082] [Chemical Formula 5-2] Li x2 Ni y2 Co z2 Mn 1-y2-z2 O2 In Chemical Formula 5-2, 1 ≦ x2 ≦ 1.2, 0 < y2 < 1, and 0 < z2 < 1.

[0083] [Chemical Formula 5-3] Li x3 CoO2 In Chemical Formula 5-3, 0.5 < x3 ≦ 1.

[0084] As an example, in Chemical Formula 5-1, 1 ≦ x1 ≦ 1.2, 0.5 ≦ y1 < 1, and 0 < z1 ≦ 0.5 may be satisfied.

[0085] As a specific example, in Chemical Formula 5-1, 1 ≦ x1 ≦ 1.2, 0.

[0086] As a more specific example, in Chemical Formula 5-1, 1 ≦ x1 ≦ 1.2, 0.7 ≦ y1 < 1, and 0 < z1 ≦ 0.5 can hold.

[0087] For example, in Chemical Formula 5-1, 1 ≦ x1 ≦ 1.2, 0.8 ≦ y1 < 1, and 0 < z1 ≦ 0.5 can hold.

[0088] As an example, in Chemical Formula 5-2, 1 ≦ x2 ≦ 1.2, 0.3 ≦ y2 < 1, and 0.3 ≦ z2 < 1 can hold.

[0089] As a specific example, in Chemical Formula 5-2, 1 ≦ x2 ≦ 1.2, 0.6 ≦ y2 < 1, and 0.3 ≦ z2 < 1 can hold.

[0090] As a more specific example, in Chemical Formula 5-2, 1 ≦ x2 ≦ 1.2, 0.7 ≦ y2 < 1, and 0.3 ≦ z2 < 1 can hold.

[0091] For example, in Chemical Formula 5-2, 1 ≦ x2 ≦ 1.2, 0.8 ≦ y2 < 1, and 0.3 ≦ z2 < 1 can hold.

[0092] The content of the positive electrode active material can be 90% to 98% by weight based on the total weight of the positive electrode active material layer.

[0093] In one embodiment of the present invention, the positive electrode active material layer can selectively include a conductive material and a binder. At this time, the contents of the conductive material and the binder can each be 1% to 5% by weight based on the total weight of the positive electrode active material layer.

[0094] The conductive material is used to impart conductivity to the positive electrode, and any electron-conductive material that does not undergo chemical change in the battery that is constructed can be used. Examples of conductive materials that can be used include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber; metal-based materials such as metal powder or metal fiber of copper, nickel, aluminum, silver, and the like; conductive polymers such as polyphenylene derivatives; and conductive materials containing mixtures of these.

[0095] The binder serves to favorably adhere positive electrode active material particles to each other and to favorably adhere the positive electrode active material to a current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, and nylon.

[0096] The positive electrode current collector may be made of Al, but is not limited thereto.

[0097] The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector and containing a negative electrode active material.

[0098] The negative electrode active material includes a material capable of reversibly inserting / extracting lithium ions, lithium metal, a lithium metal alloy, a material capable of being doped with and dedoped from lithium, or a transition metal oxide.

[0099] As the substance capable of reversibly inserting / desorbing the lithium ions, carbon substances can be used, and any carbon-based negative electrode active material generally used in lithium secondary batteries can be used. Representative examples thereof include crystalline carbon, amorphous carbon, or both of these can be used. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flaky, spherical or fibrous natural graphite or artificial graphite. Examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, fired coke, etc.

[0100] As the alloy of the lithium metal, an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn can be used.

[0101] As the substance capable of doping and undoping lithium, Si, Si-C composite, SiOx(0 < x < 2), Si-Q alloy (where Q is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements and combinations thereof, and is not Si), Sn, SnO2, Sn-R 22 (where the R 22 is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements and combinations thereof, and is not Sn), etc. can be mentioned, and at least one of these can also be mixed with SiO2 and used.

[0102] The elements Q and R 22As the metal, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof can be used.

[0103] Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, and lithium titanium oxide.

[0104] In a specific embodiment, the negative electrode active material may be a Si-C composite including a Si-based active material and a carbon-based active material.

[0105] In the Si—C composite, the average particle size of the Si-based active material may be 50 nm to 200 nm.

[0106] When the average particle size of the Si-based active material is within the above range, volume expansion that occurs during charge and discharge can be suppressed, and conductive path disconnection due to particle crushing during charge and discharge can be prevented.

[0107] The Si-based active material may be included in an amount of 1 to 60 wt %, for example, 3 to 60 wt %, based on the total weight of the Si-C composite.

[0108] In another specific embodiment, the negative electrode active material may further include crystalline carbon in addition to the Si—C composite.

[0109] When the negative electrode active material includes both a Si-C composite and crystalline carbon, the Si-C composite and crystalline carbon may be included in the form of a mixture, in which case the Si-C composite and crystalline carbon may be included in a weight ratio of 1:99 to 50:50. More specifically, the Si-C composite and crystalline carbon may be included in a weight ratio of 5:95 to 20:80.

[0110] The crystalline carbon may include, for example, graphite, and more specifically, may include natural graphite, artificial graphite, or a mixture thereof.

[0111] The average particle size of the crystalline carbon may be 5 μm to 30 μm.

[0112] In this specification, the average particle size may be the particle size at 50% by volume (D50) in the cumulative size-distribution curve.

[0113] The Si—C composite may further include a shell surrounding the surface of the Si—C composite, and the shell may include amorphous carbon.

[0114] The amorphous carbon may include soft carbon, hard carbon, mesophase pitch charcoal, calcined coke, or a mixture thereof.

[0115] The amorphous carbon may be included in an amount of 1 to 50 parts by weight, for example, 5 to 50 parts by weight, or 10 to 50 parts by weight, relative to 100 parts by weight of the carbon-based active material.

[0116] The content of the negative electrode active material in the negative electrode active material layer may be 95% by weight to 99% by weight based on the total weight of the negative electrode active material layer.

[0117] In one embodiment of the present invention, the negative electrode active material layer includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt % to 5 wt % based on the total weight of the negative electrode active material layer. When the negative electrode active material layer further includes a conductive material, the negative electrode active material may be 90 wt % to 98 wt %, the binder may be 1 wt % to 5 wt %, and the conductive material may be 1 wt % to 5 wt %.

[0118] The binder serves to effectively adhere the negative electrode active material particles to each other and to the current collector. The binder may be a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0119] The non-water-soluble binder may be polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0120] The water-soluble binder may be a rubber-based binder or a polymer resin binder. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polytetrafluoroethylene, ethylene-propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0121] When a water-soluble binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included as a thickener. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal may be Na, K, or Li. The amount of the thickener used may be 0.1 to 3 parts by weight per 100 parts by weight of the negative electrode active material.

[0122] The conductive material is used to impart conductivity to the electrodes, and any electron-conductive material that does not undergo chemical change in the battery that is constructed can be used. Examples of conductive materials that can be used include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber; metal-based materials such as metal powder or metal fiber of copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and conductive materials containing mixtures of these.

[0123] The negative electrode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0124] Depending on the type of lithium secondary battery, a separator may be present between the positive electrode and the negative electrode. Such a separator may be a porous substrate or a composite porous substrate.

[0125] The porous substrate is a substrate containing voids through which lithium ions can move. The porous substrate may be, for example, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof. Of course, a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may also be used.

[0126] The composite porous substrate may include a porous substrate and a functional layer disposed on the porous substrate. The functional layer may be, for example, at least one of a heat-resistant layer and an adhesive layer, which allows for additional functionality to be added. For example, the heat-resistant layer may include a heat-resistant resin and, optionally, a filler.

[0127] The adhesive layer may include an adhesive resin and optionally a filler.

[0128] The filler can be an organic filler or an inorganic filler. [Example]

[0129] Examples of the present invention and comparative examples are described below. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0130] Synthesis example: Synthesis of compound 1-b [ka] The compound 1-b was synthesized with reference to published patent application KR2013-0124180.

[0131] Fabrication of lithium secondary batteries Example 1 LiNi as a positive electrode active material 0.91 Co 0.07 Al 0.02 O2, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed in a weight ratio of 97:2:1, and dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0132] The positive electrode active material slurry was coated on an aluminum foil having a thickness of 14 μm, dried at 110° C., and then pressed to prepare a positive electrode.

[0133] A mixture of artificial graphite and Si-C composite in a weight ratio of 93:7 was used as the negative electrode active material. The negative electrode active material, styrene-butadiene rubber binder, and carboxymethyl cellulose as a thickener were mixed in a weight ratio of 97:1:2, respectively, and dispersed in distilled water to prepare a negative electrode active material slurry.

[0134] The Si-C composite has a core containing artificial graphite and silicon particles, and the surface of the core is coated with coal-based pitch.

[0135] The negative electrode active material slurry was coated on a copper foil having a thickness of 10 μm, dried at 100° C., and then pressed to prepare a negative electrode.

[0136] The prepared positive and negative electrodes were assembled with a 25 μm thick polyethylene separator to prepare an electrode assembly, and an electrolyte solution was injected into the assembly to prepare a lithium secondary battery.

[0137] The composition of the electrolyte is as follows: (Electrolyte composition) Salt: LiPF61.5M Solvent: ethylene carbonate: ethyl methyl carbonate: dimethyl carbonate (EC:EMC:DMC = 20:10:70 volume ratio) Additive: Composition containing 5.0% by weight of compound 1-a and 0.5% by weight of compound 2-a (However, the "wt %" in the composition of the electrolyte solution is based on the total content (lithium salt + non-aqueous organic solvent).) [ka]

[0138] Example 2 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the amount of the compound 1-a to 2.5 wt %.

[0139] Example 3 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the amount of the compound 1-a to 1.5 wt %.

[0140] Example 4 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to 1.0 wt %.

[0141] Example 5 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to 0.5 wt %.

[0142] Example 6 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to 0.25% by weight.

[0143] Example 7 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the amount of the compound 2-a to 1.0 wt %.

[0144] Example 8 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the amount of the compound 2-a to 2.5 wt %.

[0145] Example 9 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 2-a to 5.0 wt %.

[0146] Example 10 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to the compound 1-b.

[0147] Example 11 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 2-a to the compound 2-d. [ka]

[0148] Comparative Example 1 A lithium secondary battery was fabricated in the same manner as in Example 1, except that an electrolyte solution containing no additives was used.

[0149] Comparative Example 2 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the electrolyte solution was prepared using an additive that did not contain Compound 2-a of the composition.

[0150] Comparative Example 3 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the electrolyte solution was prepared using an additive that did not contain Compound 1-a of the composition.

[0151] Comparative Example 4 A lithium secondary battery was produced in the same manner as in Example 1, except that the additive composition was produced by changing compound 2-a in the composition to the following compound i (Tris(1,1,1,3,3,3-hexafluoroisopropyl) phosphate). [ka]

[0152] Comparative Example 5 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 2-a in the composition to the following compound ii (Tris(trimethylsilyl) phosphite). [ka]

[0153] Comparative Example 6 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to 0.05% by weight.

[0154] Comparative Example 7 A lithium secondary battery was fabricated in the same manner as in Example 1, except that the additive composition was prepared by changing the compound 1-a to 10 wt %.

[0155] The additive compositions of the lithium secondary batteries according to Examples 1 to 11 and Comparative Examples 1 to 7 are as shown in Table 1 below.

[0156] [Table 1]

[0157] Evaluation 1: Penetration safety evaluation The penetration characteristics of the lithium secondary batteries according to Examples 1 to 11 and Comparative Examples 1 to 7 were evaluated by the following method, and the results are shown in Table 2 below.

[0158] The penetration limit evaluation was carried out by charging the battery to SOC (state of charge) 50 (a capacity equivalent to half of the total capacity of 100) and SOC (state of charge) 70 (a capacity equivalent to 70% of the total capacity of 100), and then penetrating the cell at a speed of 150 mm / s using a 3.0 mm nail to evaluate the safety of the battery. The evaluation criteria were as follows: (Evaluation criteria) L0: No response L1:Leakage L2: fever below 200°C L3: Smoke, fever over 200°C L4: Ignition L5: Explosion

[0159] [Table 2]

[0160] Referring to Table 2, it can be seen that the lithium secondary batteries according to Examples 1 to 11 have superior safety against penetration compared to the lithium secondary batteries according to Comparative Examples 1 to 7.

[0161] In other words, it can be seen that such excellent effects will not be realized if the composition of the additive according to the present invention does not contain any one of the compounds, if some of the compounds in the composition of the additive are changed to other types of compounds, or if the composition of the additive deviates from a specific ratio.

[0162] Evaluation 2: Evaluation of high temperature storage characteristics The lithium secondary batteries of Examples 1 to 11 and Comparative Examples 1 to 7 were charged at a 0.5C charge / discharge rate of 4.35 VCC / CV for 3 hours, and then left in a 90°C chamber for 110 hours to measure the activation time of the CID (Current Interrupt Device).

[0163] The CID (Current Interrupt Device) is a device that senses a pressure change, i.e., a pressure increase, within a sealed device and cuts off current when the pressure exceeds a certain level. This is self-evident to those skilled in the art, so further explanation will be omitted.

[0164] The high-temperature storage characteristics of the lithium secondary battery were evaluated by measuring the time when the CID was activated, and the measurement results are shown in Figure 2.

[0165] FIG. 2 is a graph showing the measurement of the activation time of the CID (Current Interrupt Device) of the lithium secondary batteries according to Examples 1 to 11 and Comparative Examples 1 to 7.

[0166] The high-temperature storage characteristics of a lithium secondary battery can be evaluated by measuring the CID activation time.

[0167] Referring to FIG. 2, when at least one of the compounds contained in the composition of the present invention is not contained as in Comparative Examples 1 to 5, a sudden voltage drop occurs before about 30 hours have passed when stored at a high temperature of 90°C. However, the examples containing the additive according to one embodiment of the present invention do not show a voltage drop until at least 50 hours have passed. This indicates that the decomposition of the electrolyte is delayed, which reduces the increase in resistance and delays the OCV drop.

[0168] In addition, even when the additive mixing ratio is outside the specific range, as in Comparative Examples 6 and 7, a sudden voltage drop occurs before about 30 hours have elapsed, but the examples containing the additive according to an embodiment of the present invention show no voltage drop for at least 50 hours, demonstrating the effect of reducing gas. This indicates that the decomposition of the electrolyte is delayed, which reduces the increase in resistance and delays the OCV drop.

[0169] In other words, the lithium secondary battery according to the present invention is excellent in the effect of suppressing gas generation during storage at high temperatures.

[0170] Therefore, in the case of a lithium secondary battery using the specific combination composition according to this embodiment as an additive, excellent penetration safety and high-temperature storage characteristics can be achieved.

[0171] Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it is to be understood that these modifications also fall within the scope of the present invention. [Explanation of symbols]

[0172] 100: Lithium secondary battery 112: Negative electrode 113: Separator 114: Positive electrode 120:Battery container 140: Sealing member

Claims

1. non-aqueous organic solvents, lithium salts, and Contains additives, The additive comprises a first compound represented by the following chemical formula 1, and A second compound which is any one selected from the compounds listed in Group 2 below. An electrolyte solution for a lithium secondary battery, the electrolyte solution comprising: 【Chemical 1】 In the above Chemical Formula 1, R １ ~R ６ are each independently hydrogen, halogen, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C1 to C10 alkoxy group, or a substituted or unsubstituted C1 to C10 alkylamine group; R １ ~R ６ at least one of which is a fluoro group (—F); The group 2 is as follows: 【Chemistry 2】

2. 2. The electrolyte solution for a lithium secondary battery according to claim 1, wherein the composition contains the first compound and the second compound in a weight ratio of 0.5:1 to 10:

1.

3. 2. The electrolyte solution for a lithium secondary battery according to claim 1, wherein the composition contains the first compound and the second compound in a weight ratio of 5:1 to 10:

1.

4. R of Formula 1 １ ~R ６ At least one of the R is a fluoro group (—F), and the remaining R １ ~R ６ 2. The electrolyte solution for a lithium secondary battery according to claim 1, wherein at least one of the groups is a substituted or unsubstituted C1 to C10 alkoxy group or a substituted or unsubstituted C1 to C10 alkylamino group.

5. 2. The electrolyte solution for a lithium secondary battery according to claim 1, wherein the first compound is represented by Chemical Formula 1, and Chemical Formula 1 is represented by the following Chemical Formula 1A or Chemical Formula 1B: 【Chemistry 3】 In Formula 1A and Formula 1B, R ７ ~R ９ are each independently a substituted or unsubstituted C1 to C10 alkyl group.

6. The electrolyte for a lithium secondary battery according to claim 1 , wherein the first compound is any one selected from the compounds listed in Group 1 below: 【Chemistry 4】

7. 2. The electrolyte solution for a lithium secondary battery according to claim 1, wherein the first compound is contained in an amount of 0.1 wt % to 5.0 wt % based on the total weight of the electrolyte solution for a lithium secondary battery.

8. 2. The electrolyte for a lithium secondary battery according to claim 1, wherein the second compound is contained in an amount of 0.1 wt % to 5.0 wt % based on the total weight of the electrolyte for a lithium secondary battery.

9. 10. The electrolyte for a lithium secondary battery according to claim 1, wherein the composition is contained in an amount of 1.0 to 10 wt % based on the total weight of the electrolyte for a lithium secondary battery.

10. a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and The electrolyte solution for a lithium secondary battery according to any one of claims 1 to 9. A lithium secondary battery comprising:

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