Lithium-ion rechargeable battery

Abstract

The present invention provides a lithium secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode active material, the positive electrode active material comprises a perlithitated manganese-rich oxide containing 50 mol% or more of Mn in the total metals excluding lithium, and having a molar ratio of lithium to transition metals of more than 1, and the non-aqueous electrolyte comprises a lithium salt, a compound represented by chemical formula 1, and a compound represented by chemical formula 2.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0126665 filed on September 21, 2023, and all the contents disclosed in the documents of the Korean Patent Application are incorporated herein by reference in their entirety.

[0002] The present invention relates to a lithium secondary battery. Specifically, the present invention relates to a lithium secondary battery including over-lithiated manganese-rich oxide as a positive electrode active material.

Background Art

[0003] In recent years, the application fields of lithium secondary batteries have rapidly expanded not only to power supply for electronic devices such as electric, electronic, communication, and computer devices, but also to power storage and supply for large-area devices such as automobiles and power storage devices. Along with this, the need for secondary batteries with high capacity, high output, and high stability has been increasing.

[0004] The lithium secondary battery generally includes a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, an electrolyte serving as a medium for transmitting lithium ions, and a separator. At this time, as the negative electrode active material, a carbon-based active material, a silicon-based active material, etc. can be used. Also, as the positive electrode active material, lithium transition metal oxides such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and lithium nickel-cobalt-manganese composite oxide can be used.

[0005] Recently, perlithium manganese-rich oxide has attracted attention as a next-generation cathode active material. Perlithium manganese-rich oxide has a relatively high content of manganese (Mn), which is relatively inexpensive and abundant in reserves, and has the advantage of having a high capacity. However, in the activation and charge / discharge processes, the electrolyte is severely decomposed by reactive oxygen generated by the phase transformation of the cathode active material, the amount of gas generated significantly increases, and transition metals eluted from the cathode active material are electrodeposited on the anode, destroying the anode SEI film. Therefore, its utilization is limited. Such problems become even more problematic especially when driving at high temperatures and high voltages. Summary of the Invention Problems to be Solved by the Invention

[0006] One problem of the present invention is to solve the above problems, and a lithium secondary battery including a perlithium manganese-rich oxide as a cathode active material, which reduces the generation of gas during initial activation and charge / discharge, and suppresses the elution of transition metals from the cathode active material, thereby providing a lithium secondary battery having excellent high-temperature cycle characteristics and high-temperature storage characteristics. Means for Solving the Problems

[0007] [1] One aspect of the present invention provides a lithium secondary battery including a cathode, an anode, a separator interposed between the cathode and the anode, and a non-aqueous electrolyte. The cathode includes a cathode active material, and the cathode active material includes a perlithium manganese-rich oxide containing 50 mol% or more of Mn in all metals excluding lithium, and having a molar ratio of lithium to transition metals exceeding 1. The non-aqueous electrolyte includes a lithium salt, a compound represented by the following Chemical Formula 1,and a compound represented by the following Chemical Formula 2.

[0008] [Chemical Formula 1]

Chemical

[0009] In the above chemical formula 1, R1 includes halogens, nitrile groups, propagyl groups, ester groups, ether groups, ketone groups, carboxyl groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkynyl groups, substituted or unsubstituted alkoxy groups, boron groups, borate groups, isocyanate groups, isothiocyanate groups, silyl groups, siloxane groups, sulfone groups, sulfonate groups, sulfate groups, or two or more combinations thereof, and n is an integer from 0 to 6. [Chemical formula 2] [ka] In the above chemical formula 2, R2 is fluorine, a C1-C10 alkyl group substituted with one or more fluorine atoms, a C1-C10 alkoxy group substituted with one or more fluorine atoms, or a C6-C20 aryloxy group substituted with one or more fluorine atoms, and R3 and R4 are independently hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group.

[0010] [2] One aspect of the present invention provides the lithium secondary battery described in [1] above, wherein the perlithitated manganese-rich oxide comprises a compound represented by the following chemical formula A.

[0011] [Chemical formula A] Li 1+s [Ni t Co u Mn V M 1 w ]O 2+z

[0012] In the aforementioned chemical formula A, M 1 is one or more elements selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and satisfies 0.05 ≤ s ≤ 1, 0 ≤ t ≤ 0.5, 0 ≤ u ≤ 0.3, 0.5 ≤ v < 1.0, 0 ≤ w ≤ 0.2, and 0 ≤ z ≤ 1.

[0013] [3] One aspect of the present invention provides a lithium secondary battery according to either [1] or [2], wherein the compound represented by chemical formula 1 includes at least one selected from the group consisting of the compound represented by the following chemical formula 1-A and the compound represented by the following chemical formula 1-B.

[0014] [Chemical formula 1-A] [ka]

[0015] [Chemical formula 1-B] [ka]

[0016] In the aforementioned chemical formulas 1-A and 1-B, R1 has the same definition as in chemical formula 1.

[0017] [4] One aspect of the present invention provides a lithium secondary battery according to any one of [1] to [3] above, wherein the compound represented by chemical formula 1 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-9.

[0018] [Chemical formula 1-1] [ka]

[0019] [Chemical formula 1-2] [ka]

[0020] [Chemical formula 1-3] [ka]

[0021] [Chemical formula 1-4] [ka]

[0022] [Chemical formula 1-5] [ka]

[0023] [Chemical formula 1-6] [ka]

[0024] [Chemical formula 1-7] [ka]

[0025] [Chemical formula 1-8] [ka]

[0026] [Chemical formula 1-9] [ka]

[0027] [5] One aspect of the present invention provides a lithium secondary battery according to any one of [1] to [4] above, wherein the compound represented by chemical formula 1 is contained in an amount of 0.01% to 10% by weight based on the weight of the non-aqueous electrolyte.

[0028] [6] One aspect of the present invention provides a lithium secondary battery according to any one of [1] to [5] above, wherein the compound represented by chemical formula 2 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1 to 2-5.

[0029] [Chemical formula 2-1] [ka]

[0030] [Chemical formula 2-2] [Chem.]

[0031] [Chemical formula 2-3] [Chem.]

[0032] [Chemical formula 2-4] [Chem.]

[0033] [Chemical formula 2-5] [Chem.]

[0034] [7]One aspect of the present invention provides the lithium secondary battery according to any one of [1] to [6], wherein the compound represented by Chemical formula 2 is contained in the non-aqueous electrolyte at 5 wt% to 40 wt%.

[0035] [8]One aspect of the present invention provides the lithium secondary battery according to any one of [1] to [7], wherein the weight ratio of the compound represented by Chemical formula 1 and the compound represented by Chemical formula 2 is 0.01:99.1 to 50:50.

[0036] [9]One aspect of the present invention is that the lithium salt is LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10The present invention provides a lithium secondary battery according to any one of the above [1] to [8], comprising at least one selected from the group consisting of LiBOB(LiB(C2O4)2), LiCF3SO3, LiFSI(LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI(LiN(SO2CF2CF3)2).

[0037]

[10] One aspect of the present invention provides a lithium secondary battery according to any one of [1] to [9], wherein the non-aqueous electrolyte comprises an organic solvent, and the organic solvent comprises at least one selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0038]

[11] One aspect of the present invention provides a lithium secondary battery according to any one of [1] to

[10] above, wherein the nonaqueous electrolyte further comprises at least one additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propanesultone, propensultone, succinonitrile, adiponitrile, ethylene sulfate, LiBOB (Lithium bis-(oxalato)borate), LiODFB (Lithium difluorooxalatoborate), TMSPa (Tris(trimethylsilyl phosphate), and TMSPi (Tris(trimethylsilyl) Phosphite). [Effects of the Invention]

[0039] A lithium secondary battery according to one aspect of the present invention is characterized by using a perlithitated manganese-rich oxide as the positive electrode active material, and using the compound represented by chemical formula 1 and the compound represented by chemical formula 2 as the non-aqueous electrolyte component. The compound represented by chemical formula 1 is a coumarin-based compound that scavenges reactive oxygen during initial activation to prevent the consumption of organic solvents in the non-aqueous electrolyte and prevents the generation of gas due to the decomposition of organic solvents. The compound represented by chemical formula 2 is a sulfonamide-based compound that ensures the oxidative stability of the non-aqueous electrolyte and can suppress the degradation of the battery due to gas generation during charging and discharging. As a result, when the compound represented by chemical formula 1 and the compound represented by chemical formula 2 are used in combination, the initial activation and gas generation during charging and discharging of a lithium secondary battery containing a perlithitated manganese-rich oxide are reduced, and the elution of transition metals from the positive electrode active material is suppressed, thereby significantly improving the high-temperature cycle characteristics and high-temperature storage characteristics of the lithium secondary battery. [Modes for carrying out the invention]

[0040] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0041] In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the presence of implemented features, figures, steps, components, or combinations thereof, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, components, or combinations thereof.

[0042] On the other hand, before describing the present invention, unless otherwise specifically mentioned in the present invention, "*" means a connected portion (bonding site) between identical or different atoms or the terminal parts of a chemical formula.

[0043] Furthermore, in this specification, when "a to b carbon atoms" is mentioned, "a" and "b" refer to the number of carbon atoms contained in a specific functional group. That is, the functional group may contain "a" to "b" carbon atoms. For example, "alkyl group with 1 to 5 carbon atoms" means alkyl groups containing 1 to 5 carbon atoms, i.e., CH3-, CH3CH2-, CH3CH2CH2-, (CH3)2CH-, CH3CH2CH2CH2-, (CH3)2CHCH2-, CH3CH2CH2CH2CH2-, (CH3)2CHCH2CH2-, etc.

[0044] Furthermore, in this specification, alkyl groups or aryl groups may or may not be substituted. Unless otherwise defined, "substitution" means that at least one hydrogen bonded to a carbon is replaced by an element other than hydrogen, for example, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkyl group having 3 to 12 carbon atoms, an alkenyl group having 3 to 12 carbon atoms, an alkynyl group having 3 to 12 carbon atoms, an heterocycloalkyl group having 3 to 12 carbon atoms, an heterocycloalkenyl group having 3 to 12 carbon atoms, an heterocycloalkynyl group having 2 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, a halogen atom, a fluoroalkyl group having 1 to 20 carbon atoms, a nitro group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heteroaryl group having 2 to 20 carbon atoms, or a haloaryl group having 6 to 20 carbon atoms.

[0045] The present invention will be described in more detail below.

[0046] The non-aqueous electrolyte and / or lithium secondary battery according to the present invention comprises at least one of the configurations disclosed below, and may include any combination of technically possible configurations from the following configurations.

[0047] Lithium-ion rechargeable battery One aspect of the present invention relates to a lithium secondary battery.

[0048] A lithium secondary battery according to one aspect of the present invention comprises a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode active material, the positive electrode active material comprises a perlithitated manganese-rich oxide containing 50 mol% or more of Mn in the total metals excluding lithium, and having a molar ratio of lithium to transition metals of more than 1, and the non-aqueous electrolyte comprises a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2.

[0049] [Chemical formula 1] [ka]

[0050] In the above chemical formula 1, R1 includes halogen, nitrile group, propagyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted alkoxy group, boron group, borate group, isocyanate group, isothiocyanate group, silyl group, siloxane group, sulfone group, sulfonate group, sulfate group, or two or more combinations thereof, and n is an integer from 0 to 6.

[0051] [Chemical formula 2] [ka]

[0052] In the above chemical formula 2, R2 is fluorine, a C1-C10 alkyl group substituted with one or more fluorine atoms, a C1-C10 alkoxy group substituted with one or more fluorine atoms, or a C6-C20 aryloxy group substituted with one or more fluorine atoms, and R3 and R4 are independently hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group.

[0053] A lithium secondary battery according to one aspect of the present invention is characterized by using a perlithitated manganese-rich oxide as the positive electrode active material, and using the compound represented by chemical formula 1 and the compound represented by chemical formula 2 as the non-aqueous electrolyte component. The compound represented by chemical formula 1 is a coumarin-based compound that scavenges reactive oxygen during initial activation to prevent the consumption of organic solvents in the non-aqueous electrolyte and prevents the generation of gas due to the decomposition of organic solvents. The compound represented by chemical formula 2 is a sulfonamide-based compound that ensures the oxidative stability of the non-aqueous electrolyte and can suppress the degradation of the battery due to gas generation during charging and discharging. As a result, when the compound represented by chemical formula 1 and the compound represented by chemical formula 2 are used in combination, the initial activation and gas generation during charging and discharging of a lithium secondary battery containing a perlithitated manganese-rich oxide are reduced, and the elution of transition metals from the positive electrode active material is suppressed, thereby significantly improving the high-temperature cycle characteristics and high-temperature storage characteristics of the lithium secondary battery.

[0054] The lithium secondary battery includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte. Specifically, the lithium secondary battery includes a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. The lithium secondary battery can be manufactured by housing an electrode assembly, including the positive electrode, the negative electrode facing the positive electrode, and the separator interposed between the positive electrode and the negative electrode, in a battery case, and then injecting the non-aqueous electrolyte.

[0055] (1) Positive electrode The positive electrode includes a positive electrode active material.

[0056] The positive electrode active material includes a perlithitated manganese-rich oxide. The perlithitated manganese-rich oxide contains 50 mol% or more of Mn in the total metal excluding lithium, and the molar ratio of lithium to the transition metal may exceed 1.

[0057] The aforementioned perlithitated manganese-rich oxide is attracting attention as a next-generation high-capacity cathode active material, but its use is limited due to structural degradation inherent to the material. Specifically, the reactive oxygen released from the perlithitated manganese-rich oxide during initial activation decomposes and consumes organic solvents (such as ethylene carbonate) contained in the non-aqueous electrolyte, generating gas byproducts, which leads to problems such as reduced lifespan, increased resistance, and decreased safety. Furthermore, during the charge-discharge process of lithium secondary batteries containing perlithitated manganese-rich oxide, HF, a decomposition product of lithium salts, dissolves manganese from the perlithitated manganese-rich oxide. This causes oxygen, specifically reactive oxygen, to be released from the perlithitated manganese-rich oxide in order to achieve charge balance. The dissolved manganese electrodeposits onto the negative electrode, causing damage to the SEI film, and the reactive oxygen released during the charge-discharge process continuously decomposes and consumes the organic solvents of the non-aqueous electrolyte, increasing the generation of gas byproducts. The consumption of non-aqueous electrolytes, structural breakdown of perlithitated manganese-rich oxides, and increased gaseous byproducts significantly degrade the lifespan, resistance characteristics, and safety of lithium secondary batteries. Furthermore, these problems are exacerbated under high-temperature and high-voltage conditions.

[0058] To solve these problems, a lithium secondary battery according to one aspect of the present invention is characterized by using a compound represented by chemical formula 1 and a compound represented by chemical formula 2, described below, in combination as a non-aqueous electrolyte component. When both the compound represented by chemical formula 1 and the compound represented by chemical formula 2 are used, the generation of reactive oxygen in the initial activation process and the driving process of the lithium secondary battery is significantly suppressed, the structural collapse of the overlithified manganese-rich oxide is prevented, and the consumption of organic solvents is significantly reduced. As a result, a lithium secondary battery with excellent high-temperature cycle characteristics, high-temperature storage characteristics, and safety can be realized. Such effects are difficult to achieve with other lithium transition metal oxides in which the desorption of reactive oxygen is not a major problem, and the increase in initial resistance and decrease in lifespan performance due to the use of chemical formula 1 and chemical formula 2 compounds may actually become a problem.

[0059] The aforementioned perlithitated manganese-rich oxide may contain a compound represented by the following chemical formula A.

[0060] [Chemical formula A] Li 1+s [Ni t Co u Mn V M 1 w ]O 2+z

[0061] In the aforementioned chemical formula A, M 1 is one or more selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and satisfies 0.05≦s≦1, 0≦t≦0.5, 0≦u≦0.3, 0.5≦v<1.0, 0≦w≦0.2, and 0≦z≦1. Preferably, in the chemical formula X, 0.05≦s≦1.0, 0.1≦t≦0.5, 0≦u≦0.1, 0.5≦v<1.0, 0≦w≦0.2, and 0≦z≦1 may be. More preferably, in the chemical formula X, 0.10≦s≦0.50, 0.1≦t≦0.5, 0≦u≦0.1, 0.6≦v<1.0, 0≦w≦0.1, and 0≦z≦0.50 may be satisfied.

[0062] More specifically, the perlithitated manganese-rich oxide may contain a compound represented by the following chemical formula A-1.

[0063] [Chemical formula A-1] X Li2MnO3·(1-X)Li[Ni 1-y-z-w Mn y Co z M 1 w ]O2

[0064] In the above chemical formula A-1, M 1is one or more selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo. In addition, in the chemical formula Y, 0.1≦X≦0.5, 0.5≦y<1, 0≦z≦0.3, and 0≦w≦0.2 may be, preferably 0.2≦X≦0.5, 0.5≦y<1, 0≦z≦0.1, and 0≦w≦0.2, more preferably 0.3≦X≦0.5, 0.6≦y<1, 0≦z≦0.1, and 0≦w≦0.2.

[0065] The positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector. In this case, the positive electrode active material may be included in the positive electrode active material layer.

[0066] The positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity. Specifically, the positive electrode current collector may contain at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy, preferably aluminum.

[0067] The thickness of the positive electrode current collector is typically 3 to 500 μm.

[0068] The positive electrode current collector may have its surface textured to enhance the bonding force of the positive electrode active material. For example, the positive electrode current collector can be used in various forms such as film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0069] The positive electrode active material layer may be disposed on at least one side of the positive electrode current collector, specifically, on one or both sides of the positive electrode current collector.

[0070] The positive electrode active material may be included in the positive electrode active material layer in an amount of 80% to 99% by weight, preferably 92% to 98.5% by weight, taking into consideration the sufficient capacity of the positive electrode active material.

[0071] The explanation of other positive electrode active materials has been given above and will be omitted here.

[0072] The positive electrode active material layer may further include a binder and / or a conductive material together with the positive electrode active material.

[0073] The binder is a component that assists in the binding of the active material to the conductive material and to the current collector, and specifically may contain at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-dientelpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluororubber, preferably polyvinylidene fluoride.

[0074] The binder may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, from the viewpoint of ensuring sufficient binding force between components such as the positive electrode active material.

[0075] The conductive material is used to assist and improve the conductivity of a secondary battery and is not particularly limited as long as it does not cause chemical changes and is conductive. Specifically, the positive electrode conductive material may include at least one selected from the group consisting of graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives, and preferably may include carbon nanotubes in order to improve conductivity.

[0076] The conductive material may be included in the positive electrode active material layer in an amount of 1% to 20% by weight, preferably 1.2% to 10% by weight, in order to ensure sufficient electrical conductivity.

[0077] The thickness of the positive electrode active material layer may be 30 μm to 400 μm, preferably 40 μm to 110 μm.

[0078] The positive electrode can be manufactured by coating a positive electrode slurry containing a positive electrode active material and selectively a binder, conductive material, and solvent for forming the positive electrode slurry onto the positive electrode current collector, followed by drying and rolling.

[0079] The solvent for forming the positive electrode slurry may include an organic solvent such as NMP (N-methyl-2-pyrrolidone). The solid content of the positive electrode slurry may be 40% to 90% by weight, specifically 50% to 80% by weight.

[0080] (2) Negative electrode The negative electrode faces the positive electrode.

[0081] The aforementioned negative electrode contains a negative electrode active material.

[0082] The negative electrode active material is a material capable of reversibly intercalating / deintercalating lithium ions, and may include at least one selected from the group consisting of carbon-based active materials, metalloid-based active materials, and lithium metal. Specifically, it may include at least one selected from carbon-based active materials and metalloid-based active materials.

[0083] The carbon-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, graphene, and fibrous carbon, and preferably includes at least one selected from the group consisting of artificial graphite and natural graphite.

[0084] The average particle size (D) of the carbon-based active material 50The thickness of the ) may be 10 μm to 30 μm, preferably 15 μm to 25 μm, in order to ensure structural stability during charging and discharging and to reduce side reactions with the electrolyte.

[0085] Specifically, the metalloid active material may include: at least one metalloid selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an alloy of lithium with at least one metalloid selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; an oxide of at least one metalloid selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, V, Ti, and Sn; lithium titanium oxide (LTO); lithium vanadium oxide; and the like.

[0086] More specifically, the metalloid-based active material may include a silicon-based active material.

[0087] The silicon-based active material is SiO x The compound may include compounds represented by (0 ≤ x < 2) and silicon-carbon composites. SiO2 does not react with lithium ions and therefore cannot store lithium. For this reason, x is preferably within the above range, and more preferably the silicon-based active material is SiO2.

[0088] The average particle size (D) of the silicon-based active material 50 The thickness of the ) may be 1 μm to 30 μm, preferably 2 μm to 15 μm, in order to ensure structural stability during charging and discharging and to reduce side reactions with the electrolyte.

[0089] The negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector. In this case, the negative electrode active material may be contained in the negative electrode active material layer.

[0090] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Specifically, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy.

[0091] The negative electrode current collector typically has a thickness of 3 to 500 μm.

[0092] The negative electrode current collector may have its surface textured to enhance the bonding force of the negative electrode active material. For example, the negative electrode current collector can be used in various forms such as film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0093] The negative electrode active material layer may be disposed on at least one side of the negative electrode current collector, specifically, on one or both sides of the negative electrode current collector.

[0094] The negative electrode active material may be included in the negative electrode active material layer in an amount of 60% to 99% by weight, preferably 75% to 95% by weight.

[0095] Further explanation regarding the positive electrode active material has been given above and will therefore be omitted.

[0096] The negative electrode active material layer may further include a binder and / or a conductive material together with the negative electrode active material.

[0097] The binder is used to improve the performance of the battery by improving the adhesion between the negative electrode active material layer and the negative electrode current collector, and may contain, for example, at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and substances in which the hydrogen of these substances is substituted with Li, Na, or Ca, or may contain various copolymers thereof.

[0098] The binder may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0099] The conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive. Examples include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; fluorocarbons; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0100] The conductive material may be included in the negative electrode active material layer in an amount of 0.5% to 10% by weight, preferably 1% to 5% by weight.

[0101] The thickness of the negative electrode active material layer may be 10 μm to 200 μm, preferably 20 μm to 150 μm.

[0102] The negative electrode can be manufactured by coating at least one surface of a negative electrode current collector with a negative electrode slurry containing a negative electrode active material, a binder, a conductive material, and / or a solvent for forming the negative electrode slurry, followed by drying and rolling.

[0103] The solvent for forming the negative electrode slurry may include, for example, at least one selected from the group consisting of distilled water, NMP (N-methyl-2-pyrrolidone), ethanol, methanol, and isopropyl alcohol, preferably distilled water, in order to facilitate the dispersion of the negative electrode active material, binder, and / or conductive material. The solid content of the negative electrode slurry may be 30% to 80% by weight, specifically 40% to 70% by weight.

[0104] (3) Separator The separator can be interposed between the positive electrode and the negative electrode.

[0105] Furthermore, the separator may be a conventional porous polymer film, such as a porous polymer film made from polyolefin polymers like ethylene monopolymer, propylene monopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, used alone or in a laminated configuration. Alternatively, a conventional porous nonwoven fabric, such as a nonwoven fabric made from high-melting-point glass fibers or polyethylene terephthalate fibers, may be used, but is not limited to these. In addition, a coated separator containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and may be used selectively as a single-layer or multi-layer structure.

[0106] (4) Non-aqueous electrolytes A nonaqueous electrolyte according to one aspect of the present invention comprises a lithium salt, a compound represented by chemical formula 1 described below, and a compound represented by chemical formula 2 below. The nonaqueous electrolyte may further contain an organic solvent and an additive, as it may optionally. In this case, the organic solvent and the additive are used as terms to distinguish them from the compound represented by chemical formula 1 and the compound represented by chemical formula 2.

[0107] 1) Lithium salt The lithium salt used in this invention is not limited to any particular lithium salt commonly used in non-aqueous electrolytes for lithium secondary batteries. For example, the lithium salt may contain Li as a cation. + It includes, as an anion, F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - ClO4 - AlO4 - AlCl4 - PF6 - SbF6 - AsF6 - B 10 Cl 10 - BF2C2O4 - BC4O8 - PF4C2O4 - PF2C4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - , C4F9SO3 - CF3CF2SO3 - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - CH3SO3 - CF3(CF2)7SO3 - CF3CO2 -CH3CO2 - SCN - , and (CF3CF2SO2)2N - It may include at least one selected from the group consisting of the following.

[0108] Specifically, the lithium salts are LiCl, LiBr, LiI, LiBF4, LiClO4, LiAlO4, LiAlCl4, LiPF6, LiSbF6, LiAsF6, LiB 10 Cl 10 The lithium salt may include at least one selected from the group consisting of LiBOB(LiB(C2O4)2), LiCF3SO3, LiFSI(LiN(SO2F)2), LiCH3SO3, LiCF3CO2, LiCH3CO2, and LiBETI(LiN(SO2CF2CF3)2). Specifically, the lithium salt may include at least one selected from the group consisting of LiBF4, LiClO4, LiPF6, LiBOB(LiB(C2O4)2), LiCF3SO3, LiTFSI(LiN(SO2CF3)2), LiFSI((LiN(SO2F)2), and LiBETI(LiN(SO2CF2CF3)2).

[0109] The lithium salt may be included in the non-aqueous electrolyte at a concentration of 0.5 M to 5 M, specifically, 0.8 M to 4 M, and more specifically, 0.8 M to 2.0 M. When the concentration of the lithium salt satisfies the above range, the lithium ion transport fraction (Li + The transference number and the degree of lithium ion dissociation are improved, which can enhance the battery's output characteristics.

[0110] Alternatively, the lithium salt may be included in the non-aqueous electrolyte as a component of the non-aqueous electrolyte, for example, the compound represented by chemical formula 1, the compound represented by chemical formula 2, an organic solvent, and the remainder after selectively removing additives.

[0111] 2) Compounds represented by chemical formula 1 A non-aqueous electrolyte according to one aspect of the present invention comprises a compound represented by the following chemical formula 1.

[0112] [Chemical formula 1] [ka]

[0113] In the above chemical formula 1, R1 includes halogen, nitrile group, propagyl group, ester group, ether group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted alkoxy group, boron group, borate group, isocyanate group, isothiocyanate group, silyl group, siloxane group, sulfone group, sulfonate group, sulfate group, or two or more combinations thereof, and n is an integer from 0 to 6.

[0114] The compound represented by chemical formula 1 is a coumarin-based compound that can capture reactive oxygen released from the perlithitated manganese-rich oxide during initial activation. Therefore, the use of the compound represented by chemical formula 1 can prevent the decomposition of organic solvents and the increase in gaseous byproducts that are concerns when reactive oxygen is generated during the initial activation process.

[0115] Furthermore, the compound represented by chemical formula 1 can undergo ring-opening during initial activation to form a polyethylene oxide-based polymer coating on the electrode, and such a polymer coating exhibits excellent flexibility and resilience. In particular, since an inorganic coating such as LiF, formed by the decomposition of the compound represented by chemical formula 2 described later, is compounded with the polymer coating, a non-aqueous electrolyte according to one aspect of the present invention contains both inorganic and non-aqueous components, and can form a coating on the electrode with improved flexibility, resilience, and durability, thereby further improving high-temperature life characteristics and high-temperature storage characteristics.

[0116] However, apart from its ability to remove reactive oxygen in the initial activation process, the compound represented by chemical formula 1 is not effective in removing reactive oxygen generated during the charging, discharging, or storage of lithium secondary batteries. Such reactive oxygen generated during the charging, discharging, or storage of lithium secondary batteries produces H2O as a reaction byproduct with the electrolyte, and H2O decomposes lithium salts to generate HF. Such HF dissolves manganese from the overlithified manganese-rich oxide and removes oxygen, which may accelerate the deterioration of lifespan and storage performance. In one aspect of the present invention, in order to solve this problem, the compound represented by chemical formula 2 is used together with the compound represented by chemical formula 1 to remove HF generated under conditions such as charging, discharging, and storage, thereby blocking the possibility of reactive oxygen generation during the charging, discharging, and storage of lithium secondary batteries. Therefore, in one aspect of the present invention, by using both the compound represented by chemical formula 1 and the compound represented by chemical formula 2, the generation of reactive oxygen, which is particularly problematic in perlithitated manganese-rich oxides, can be controlled, thereby improving the lifespan, storage performance, and safety of lithium secondary batteries. In particular, the lifespan, storage performance, and safety when operated at high temperature and high voltage can be improved to a remarkable level.

[0117] In the above chemical formula 1, R1 may specifically be a halogen (the halogen may be selected from F, Cl, Br, and I, and specifically may be F), a nitrile group, a propagyl group, an ester group, an ether group, or a combination of two or more of these. Such substituents improve the reducing properties of the compound represented by the above chemical formula 1, and can also achieve reactive oxygen scavenging ability, as well as the effect of smooth formation of the SEI film and improved lithium ion transfer performance.

[0118] In the aforementioned chemical formula 1, n may be an integer selected from 0 to 6, more specifically an integer selected from 1 to 6, and more specifically, n may be 1. In the aforementioned chemical formula 1, when n is 2 or greater, each R1 may be the same or different from one another.

[0119] Specifically, the compound represented by chemical formula 1 may include at least one compound selected from the group consisting of the compound represented by chemical formula 1-A and the compound represented by chemical formula 1-B.

[0120] [Chemical formula 1-A] [ka]

[0121] [Chemical formula 1-B] [ka]

[0122] In the aforementioned chemical formulas 1-A and 1-B, R1 has the same definition as in chemical formula 1.

[0123] The compounds represented by chemical formulas 1-A and 1-B have substituents at positions 3 and 7 (according to IUPAC nomenclature standards) of the ring structure, respectively. In this case, synthesis at these positions is advantageous compared to other substitution positions and is therefore preferred.

[0124] Specifically, the compound represented by chemical formula 1 may include at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-9. The compound represented by chemical formula 1 may include at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-4, 1-6, and 1-8, since it is smoothly reduced by the negative electrode and is more advantageous in the formation of the SEI film. More specifically, it may include at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 and 1-2, and even more specifically, it may include the compound represented by the following chemical formula 1-1.

[0125] [Chemical formula 1-1] [ka]

[0126] [Chemical Formula 1-2]

change

[0127] [Chemical Formulas 1-3]

change

[0128] [Chemical Formulas 1-4]

change

[0129] [Chemical Formulas 1-5]

change

[0130] [Chemical Formulas 1-6]

change

[0131] [Chemical Formulas 1-7]

change

[0132] [Chemical Formulas 1-8]

change

[0133] [Chemical Formulas 1-9]

change

[0134] The compound represented by chemical formula 1 may be present in the non-aqueous electrolyte in an amount of 0.01% to 10% by weight, specifically 0.05% to 5% by weight, more specifically 0.1% to 1% by weight, and more specifically 0.3% to 0.7% by weight. When the content of the compound represented by chemical formula 1 is within the above range, the reactive oxygen capture effect generated during initial activation can be fully exerted, and concerns about increased resistance when added in excess can be prevented.

[0135] 3) Compounds represented by chemical formula 2 A non-aqueous electrolyte according to one aspect of the present invention comprises a compound represented by the following chemical formula 2.

[0136] [Chemical formula 2] [ka]

[0137] In the above chemical formula 2, R2 is fluorine, a C1-C10 alkyl group substituted with one or more fluorine atoms, a C1-C10 alkoxy group substituted with one or more fluorine atoms, or a C6-C20 aryloxy group substituted with one or more fluorine atoms, and R3 and R4 are independently hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group.

[0138] The compound represented by chemical formula 2 is a sulfonamide compound containing a fluorine-containing substituent, and when included in a non-aqueous electrolyte, it can significantly improve the oxidative stability of the solvent. Specifically, the compound represented by chemical formula 2 improves the oxidative stability of the solvent in the charge-discharge process rather than the initial activation process, thereby preventing electrolyte side reactions and significantly reducing the generation of gas. Therefore, a non-aqueous electrolyte according to one aspect of the present invention can significantly suppress gas generation during the battery operation process, not to mention the initial activation process, and as a result, significantly improve the high-temperature storage characteristics, high-temperature life characteristics, and resistance characteristics of a lithium secondary battery containing a perlithitated manganese-rich oxide. The compound represented by chemical formula 2 has a minute oxygen capture effect during initial activation and therefore cannot prevent the generation of reactive oxygen, which is a problem during initial activation. Therefore, the effects targeted by the present invention cannot be achieved without using the compound represented by chemical formula 1 and the compound represented by chemical formula 2 in combination.

[0139] Furthermore, the compound represented by chemical formula 2 contains fluorine, and during decomposition, it can impart an inorganic film such as LiF to the electrode. Since this inorganic film is compounded with a polymer film derived from the compound represented by chemical formula 1, a film with improved flexibility, resilience, and durability can be formed on the electrode, further improving high-temperature lifespan and high-temperature storage characteristics.

[0140] R2 is fluorine, a C1-C10 alkyl group substituted with one or more fluorine atoms, a C1-C10 alkoxy group substituted with one or more fluorine atoms, or a C6-C20 aryloxy group substituted with one or more fluorine atoms. Specifically, it may be fluorine or a C1-C10 alkoxy group substituted with one or more fluorine atoms; more specifically, it may be fluorine or a C1-C5 alkoxy group substituted with one or more fluorine atoms; more specifically, it may be fluorine, CF3O-, CF3CF2O-, or CF3CH2O-; and more specifically, it may be fluorine or CF3CH2O-.

[0141] R3 and R4 may be independently hydrogen, a C1-C10 alkyl group, or a C6-C20 aryl group, more specifically hydrogen or a C1-C5 alkyl group, more specifically a C1-C5 alkyl group, and even more specifically a methyl group.

[0142] Specifically, the compound represented by chemical formula 2 may include at least one compound selected from the group consisting of compounds represented by chemical formulas 2-1 to 2-5 below. More specifically, the compound represented by chemical formula 2 may include at least one compound selected from the group consisting of compounds represented by chemical formulas 2-1 to 2-3 below. Even more specifically, the compound represented by chemical formula 2 may include at least one compound selected from the group consisting of compounds represented by chemical formulas 2-1 and 2-2 below.

[0143] [Chemical formula 2-1] [ka]

[0144] [Chemical formula 2-2] [ka]

[0145] [Chemical formula 2-3] [ka]

[0146] [Chemical formula 2-4] [ka]

[0147] [Chemical formula 2-5] [ka]

[0148] The compound represented by chemical formula 2 may be included in the non-aqueous electrolyte in an amount of 5% to 40% by weight, specifically 8% to 30% by weight, more specifically 10% to 25% by weight, and even more specifically 15% to 22% by weight. When the compound represented by chemical formula 2 is included within the above content range, the oxidation stability of the solvent can be sufficiently improved, and problems such as decreased electrode impregnation due to increased viscosity of the non-aqueous electrolyte caused by excessive addition, and decreased solubility of non-aqueous electrolyte components such as additives can be prevented.

[0149] On the other hand, when expressing the content of the compound represented by chemical formula 2 in a non-aqueous electrolyte as a volume percentage, the compound represented by chemical formula 2 may be present in the non-aqueous electrolyte in an amount of 5% to 40% by volume, specifically 12% to 25% by volume.

[0150] The weight ratio of the compound represented by chemical formula 1 to the compound represented by chemical formula 2 may be 0.01:99.99 to 50:50, specifically 0.1:99.9 to 40:60, more specifically 0.2:99.8 to 30:70, even more specifically 0.5:99.5 to 10:90, even more specifically 0.5:99.5 to 7:93, and even more specifically 2:98 to 4:96. When the ratio is within the above range, an overall excellent gas reduction effect can be achieved during the initial activation and battery drive processes described above.

[0151] 4) Organic solvents The non-aqueous electrolyte may further contain an organic solvent along with the aforementioned components.

[0152] The aforementioned organic solvent is not particularly limited as long as it is a non-aqueous solvent commonly used in lithium secondary batteries and can minimize decomposition by oxidation reactions during the charging and discharging process of the secondary battery.

[0153] The organic solvent may be contained in a non-aqueous electrolyte as a remainder after removing the lithium salt, the compound represented by chemical formula 1, the compound represented by chemical formula 2, and other selectively included additives.

[0154] Specifically, the organic solvent may include at least one selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

[0155] Specifically, the organic solvent may include a cyclic carbonate organic solvent, a linear carbonate organic solvent, or a mixture thereof.

[0156] The cyclic carbonate-based organic solvent is a highly viscous organic solvent with a high dielectric constant that readily dissociates lithium salts in electrolytes. Specifically, it may contain at least one organic solvent selected from the group consisting of ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate. More specifically, it may contain at least one selected from the group consisting of ethylene carbonate (EC) and fluoroethylene carbonate (FEC). Even more specifically, it may contain ethylene carbonate (EC).

[0157] Furthermore, the linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and may specifically include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethyl methyl carbonate (EMC), methyl propyl carbonate, and ethyl propyl carbonate. More specifically, it may include at least one selected from the group consisting of ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), and even more specifically, it may include ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). When the linear carbonate-based organic solvent contains ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), the weight ratio of ethyl methyl carbonate (EMC) to diethyl carbonate (DEC) may be 50:50 to 99:1, specifically 75:25 to 95:5, and more specifically 80:20 to 90:10.

[0158] Specifically, the organic solvent may include a cyclic carbonate organic solvent and a linear carbonate organic solvent.

[0159] When the organic solvent includes both a cyclic carbonate organic solvent and a linear carbonate organic solvent, the weight ratio of the compound represented by chemical formula 2 to the organic solvent may be 5:95 to 45:55, specifically 10:90 to 35:65, and more specifically 15:85 to 25:75. When the ratio is within this range, the effect of improving the oxidative stability of the solvent can be further enhanced.

[0160] If the organic solvent includes a cyclic carbonate organic solvent and a linear carbonate organic solvent, the weight ratio of the cyclic carbonate organic solvent to the linear carbonate organic solvent may be 10:90 to 50:50, specifically 20:80 to 40:60.

[0161] The linear ester-based organic solvent may specifically include at least one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0162] Furthermore, the cyclic ester organic solvent may specifically include at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0163] On the other hand, the organic solvent may be further used with any organic solvent commonly used for non-aqueous electrolytes, without limitation, as needed. For example, it may further contain at least one or more organic solvents such as ether-based organic solvents, glyme-based solvents, and nitrile-based organic solvents.

[0164] The ether-based solvent can be any one selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, 1,3-dioxolane (DOL), and 2,2-bis(trifluoromethyl)-1,3-dioxolane (TFDOL), or a mixture of two or more of these, but is not limited to these.

[0165] The aforementioned glyme-based solvent is a solvent that has a higher dielectric constant and lower surface tension than linear carbonate-based organic solvents, and has low reactivity with metals, and may include, but is not limited to, at least one selected from the group consisting of dimethoxyethane (glyme, DME), diethoxyethane, diglyme, triglyme, and tetraglyme (TEGDME).

[0166] The nitrile solvent may be one or more selected from the group consisting of acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile, but is not limited to these.

[0167] 5) Additives The non-aqueous electrolyte may further contain additives in addition to the aforementioned components.

[0168] Specifically, the additive may be at least one selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, propane sultone, propene sultone, succinonitrile, adiponitrile, ethylene sulfate, LiODFB (Lithium difluorooxalatoborate), LiBOB (Lithium bis-(oxalato)borate), TMSPa (3-trimethoxysilanyl-propyl-N-aniline), and TMSPi (Tris(trimethylsilyl) Phosphite).

[0169] The additive may be included in the non-aqueous electrolyte in an amount of 0.1% to 15% by weight.

[0170] The external shape of the lithium secondary battery according to one aspect of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch-shaped, or coin-shaped using a can.

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

[0172] Examples and Comparative Examples Example 1 (Manufacturing of non-aqueous electrolytes) A non-aqueous electrolyte was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-1, LiPF6 as a lithium salt, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0173] (Manufacturing of lithium-ion batteries) Cathode active material (Li 1.35 [Ni 0.360 Co 0.005 Mn 0.635 A cathode mixture slurry (65% solids by weight) was prepared by adding O2 (perlithiated manganese-rich oxide), a conductive material (carbon nanotube), and a binder (polyvinylidene fluoride) in a weight ratio of 96.0:1.5:2.5 to the solvent N-methyl-2-pyrrolidone (NMP). The cathode mixture slurry was applied to one surface of a 12 μm thick cathode current collector (a thin Al film), and the cathode was manufactured by drying and roll pressing.

[0174] A negative electrode slurry (50% solids by weight) was prepared by adding a negative electrode active material (a mixture of artificial graphite and natural graphite in a weight ratio of 50.3:49.7), a conductive material (carbon black), and a binder (styrene-butadiene rubber) in a weight ratio of 96.7:1.0:2.3 to distilled water, which was used as a solvent. The negative electrode slurry was applied to one surface of an 8 μm thick negative electrode current collector (Cu thin film), and the negative electrode was manufactured by drying and roll pressing.

[0175] In a dry room, a polyethylene porous film separator was interposed between the positive electrode and negative electrode manufactured as described above, and then the non-aqueous electrolyte manufactured as described above was injected to produce a secondary battery.

[0176] Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 1.0:18.5:14.0:20.0:39.0:7.5.

[0177] Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.1:18.5:14.0:20.0:39.7:7.7.

[0178] Example 4 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:27.0:14.0:20.0:31.0:7.5.

[0179] Example 5 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:9.4:14.2:20.6:47.7:7.6.

[0180] Example 6 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-1, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0181] Example 7 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, the compound represented by chemical formula 2-2, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0182] Example 8 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compounds represented by chemical formulas 1-3, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0183] Example 9 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compounds represented by chemical formulas 1-4, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0184] Example 10 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compounds represented by chemical formulas 1-6, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0185] Example 11 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compounds represented by chemical formulas 1-8, the compound represented by chemical formula 2-1, and LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:18.5:14.0:20.0:39.5:7.5.

[0186] Comparative Example 1 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte prepared by mixing LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a weight ratio of 14.5:21.0:56.8:7.7 was used as the lithium salt.

[0187] Comparative Example 2 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 1-2, LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 0.5:14.5:20.9:56.4:7.7.

[0188] Comparative Example 3 A lithium secondary battery was manufactured in the same manner as in Example 1, except that a non-aqueous electrolyte was used, which was prepared by mixing the compound represented by chemical formula 2-1, LiPF6, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) as lithium salts in a weight ratio of 18.6:14.1:20.4:39.4:7.5.

[0189] Experimental Example 1: Evaluation of High-Temperature Cycle Charge / Discharge Performance The lithium secondary batteries of Examples 1-11 and Comparative Examples 1-3, manufactured as described above, were charged to 4.35V and 1 / 20C at 45°C under CC / CV and 0.33C conditions using an electrochemical charge / discharger. One cycle consisted of charging to 2.5V under CC and 0.33C conditions, and 150 charge / discharge cycles were performed. The capacity retention rate, resistance increase rate, gas generation amount, and metal elution amount were evaluated as follows.

[0190] Experimental Example 1-1: Evaluation of Volume Retention Rate After charging and discharging under the above conditions, the capacity retention rate was calculated using the following formula, and the results are shown in Table 1 below.

[0191] Capacity retention rate (%) = {(Discharge capacity after 150 cycles / Discharge capacity after 1 cycle)} × 100

[0192] Experimental Example 1-2: Evaluation of resistance increase rate After 1 cycle of charge and discharge, the discharge capacity after 1 cycle was measured using an electrochemical charge and discharge device. After adjusting the SOC to 50%, a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated from the difference between the voltage before the pulse application and the voltage after the application.

[0193] After 150 cycles of charge and discharge, the resistance after 150 cycles was calculated by the same method as above, and the resistance increase rate was calculated using the following formula. The results are shown in Table 1 below.

[0194] Resistance increase rate (%) = (Resistance after 150 cycles - Initial resistance) / Initial resistance × 100

[0195] Experimental Example 1-3: Evaluation of gas generation amount After charge and discharge under the above conditions, the gas generation amount was measured using gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 1 below.

[0196] Experimental Example 1-4: Evaluation of metal elution amount After charge and discharge under the above conditions, the concentration of the total metal eluted in the electrolyte was measured using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). The amount of metal measured by ICP analysis is shown in Table 1 below.

[0197]

Table 1

[0198] Referring to Table 1, it can be confirmed that the lithium secondary batteries of Examples 1 to 11, which use a perlithiated manganese-rich oxide as the positive electrode active material and contain both compounds represented by chemical formulas 1 and 2 in the non-aqueous electrolyte, exhibit superior levels of lifespan performance, resistance reduction effect, low gas generation, and low metal elution during cycle charge-discharge compared to Comparative Examples 1 to 3, which do not use these features.

[0199] Experimental Example 2: Evaluation of High-Temperature Storage Performance The lithium secondary batteries of Examples 1-11 and Comparative Examples 1-3, manufactured as described above, were charged to 4.35V and 1 / 20C at 25°C under CC / CV and 0.33C conditions, and then discharged to 2.5V at 0.33C to perform initial charge and discharge. Subsequently, they were charged to 4.35V and 1 / 20C at 25°C under CC / CV and 0.33C conditions, and then stored at 60°C for 8 weeks.

[0200] Experimental Example 2-1: Evaluation of Volume Retention Rate After storage, the secondary battery was charged to 4.35V and 1 / 20C under CC / CV conditions of 0.33C at 25°C, and then discharged to 2.5V at 0.33C. The capacity retention rate was evaluated using the following formula, and the results are shown in Table 2 below.

[0201] Capacity retention rate (%) = (Discharge capacity after 8 weeks of storage / Initial discharge capacity) × 100

[0202] Experimental Example 2-2: Evaluation of Resistance Increase Rate During the initial charge and discharge, the capacity was confirmed at room temperature. The SOC50 was then charged based on the discharge capacity, discharged at a current of 3C for 10 seconds, and the resistance was measured from the voltage drop difference to determine the initial resistance. After storage at 60°C for 8 weeks, the resistance was measured again using the same method to determine the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 2 below.

[0203] Resistance increase rate (%) = (Final resistance - Initial resistance) / (Initial resistance) × 100

[0204] Experimental Example 2-3: Evaluation of Gas Generation Amount After storage under the aforementioned conditions, the amount of gas generated was measured using gas chromatography-mass spectrometry (GC-MS). The results are shown in Table 2 below.

[0205] Experimental Example 2-4: Evaluation of Metal Leaching Amount After storage under the aforementioned conditions, the total concentration of metals dissolved in the electrolyte was measured using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). The amounts of metals measured by ICP analysis are shown in Table 2 below.

[0206] [Table 2]

[0207] Referring to Table 2, it can be confirmed that the lithium secondary batteries of Examples 1 to 11, which use a perlithiated manganese-rich oxide as the positive electrode active material and contain both compounds represented by chemical formulas 1 and 2 in the non-aqueous electrolyte, exhibit superior levels of lifespan performance, resistance reduction effect, low gas generation, and low metal elution during high-temperature storage compared with Comparative Examples 1 to 3, which do not use these features.

[0208] Reference example Reference example 1 (Manufacturing of non-aqueous electrolytes) A non-aqueous electrolyte was prepared using the same method as in Example 1.

[0209] (Manufacturing of lithium-ion batteries) Cathode active material (Li[Ni 0.6 Co 0.1 Mn 0.3 A cathode mixture slurry (65% solids by weight) was prepared by adding 2O2, a conductive material (carbon nanotubes), and a binder (polyvinylidene fluoride) in a weight ratio of 96.7:1.2:2.3 to the solvent N-methyl-2-pyrrolidone (NMP). The cathode mixture slurry was applied to one surface of a 12 μm thick cathode current collector (a thin Al film), and the cathode was manufactured by drying and roll pressing.

[0210] The negative electrode active material (a mixture of artificial graphite and natural graphite in a weight ratio of 50.3:49.7), the conductive material (carbon black), and the binder (styrene-butadiene rubber) were added to distilled water as a solvent in a weight ratio of 96.7:1.0:2.3 to produce a negative electrode mixture slurry (solid content: 50% by weight). The negative electrode mixture slurry was applied to one side of a negative electrode current collector (Cu thin film) with a thickness of 8 μm, followed by drying and roll pressing to produce a negative electrode.

[0211] In a dry room, after interposing a polyethylene porous film separator between the positive electrode and the negative electrode produced above, the non-aqueous electrolyte produced above was injected to produce a secondary battery.

[0212] Reference Example 2 A lithium secondary battery was produced in the same manner as in Reference Example 1, except that the non-aqueous electrolyte produced in the same manner as in Comparative Example 2 was used.

[0213] Reference Example 3 A lithium secondary battery was produced in the same manner as in Reference Example 1, except that the non-aqueous electrolyte produced in the same manner as in Comparative Example 3 was used.

[0214] Reference Experimental Example 1: Evaluation of High-Temperature Cycle Charge / Discharge Performance The lithium secondary batteries of Reference Examples 1 to 3 produced above were charged using an electrochemical charger at 45 °C under CC / CV conditions of 0.33C up to 4.35V and then charged up to 1 / 20C, and then discharged to 2.5V under CC conditions of 0.33C. One cycle was defined as such, and charge / discharge was performed for 150 cycles. The capacity retention rate, resistance increase rate, gas generation amount, and metal elution amount were evaluated as follows.

[0215] Reference Experimental Example 1-1: Evaluation of Capacity Retention Rate After charge / discharge under the above conditions, the capacity retention rate was calculated by the following formula, and the results are shown in Table 3 below.

[0216] Capacity retention rate (%) = {(Discharge capacity after 150 cycles / Discharge capacity after 1 cycle)} × 100

[0217] Reference Experiment Example 1-2: Evaluation of Resistance Increase Rate After one charge-discharge cycle, the discharge capacity after one cycle was measured using an electrochemical charger. After adjusting the SOC to 50%, a 2.5C pulse was applied for 10 seconds, and the initial resistance was calculated from the difference between the voltage before and after pulse application.

[0218] After 150 charge-discharge cycles, the resistance after 150 cycles was calculated using the same method as described above, and the resistance increase rate was calculated using the following formula. The results are shown in Table 3 below.

[0219] Resistance increase rate (%) = (Resistance after 150 cycles - Initial resistance) / Initial resistance × 100

[0220] Reference Experiment Example 2: Evaluation of High-Temperature Storage Performance The lithium secondary batteries of Reference Examples 1-3, manufactured as described above, were initially charged to 4.35V and 1 / 20C at 25°C under CC / CV and 0.33C conditions, and then discharged to 2.5V at 0.33C. Afterward, they were charged to 4.35V and 1 / 20C at 25°C under CC / CV and 0.33C conditions, and then stored at 60°C for 8 weeks.

[0221] Experimental Example 2-1: Evaluation of Volume Retention Rate After storage, the secondary battery was charged to 4.35V and 1 / 20C under CC / CV conditions of 0.33C at 25°C, and then discharged to 2.5V at 0.33C. The capacity retention rate was evaluated using the following formula, and the results are shown in Table 3 below.

[0222] Capacity retention rate (%) = (Discharge capacity after 8 weeks of storage / Initial discharge capacity) × 100

[0223] Experimental Example 2-2: Evaluation of Resistance Increase Rate During the initial charge and discharge, the capacity was confirmed at room temperature. The SOC50 was then charged based on the discharge capacity, discharged at a current of 3C for 10 seconds, and the resistance was measured from the voltage drop difference to determine the initial resistance. After storage at 60°C for 8 weeks, the resistance was measured again using the same method to determine the final resistance, and the resistance increase rate was calculated using the following formula. The results are shown in Table 3 below.

[0224] Resistance increase rate (%) = (Final resistance - Initial resistance) / (Initial resistance) × 100

[0225] [Table 3]

[0226] Referring to Table 3, it can be seen that the lithium secondary battery of Reference Example 1, in which a non-aqueous electrolyte containing compounds represented by chemical formulas 1 and 2 according to one aspect of the present invention was applied to a positive electrode active material other than a perlithitated manganese-rich oxide, actually showed a decrease in performance during cycle charge / discharge and high-temperature storage compared to Reference Examples 2 and 3, in which only one of the compounds represented by chemical formula 1 or 2 was included in the non-aqueous electrolyte. This result is thought to be because the positive electrode active materials used in Reference Examples 1 to 3 had little effect on the desorption of reactive oxygen, and the increase in resistance due to the combined use of the two compounds became an even greater problem.

Claims

1. It comprises a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte. The positive electrode includes a positive electrode active material. The positive electrode active material contains 50 mol% or more of Mn in the total metal excluding lithium, and includes a perlithitated manganese-rich oxide in which the molar ratio of lithium to the transition metal is greater than 1. A lithium secondary battery comprising a lithium salt, a compound represented by the following chemical formula 1, and a compound represented by the following chemical formula 2 as the non-aqueous electrolyte. [Chemical formula 1] 【Chemistry 1】 (In the above chemical formula 1, R １ n includes halogens, nitrile groups, propagyl groups, ester groups, ether groups, ketone groups, carboxyl groups, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkenyl groups, substituted or unsubstituted alkynyl groups, substituted or unsubstituted alkoxy groups, boron groups, borate groups, isocyanate groups, isothiocyanate groups, silyl groups, siloxane groups, sulfone groups, sulfonate groups, sulfate groups, or two or more combinations thereof, where n is an integer from 0 to 6. [Chemical formula 2] 【Chemistry 2】 (In the above chemical formula 2, R ２ R is fluorine, a C1-C10 alkyl group substituted with one or more fluorine atoms, a C1-C10 alkoxy group substituted with one or more fluorine atoms, or a C6-C20 aryloxy group substituted with one or more fluorine atoms. ３ and R ４ These are, independently of each other, hydrogen, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

2. The lithium secondary battery according to claim 1, wherein the perlithitated manganese-rich oxide includes a compound represented by the following chemical formula A. [Chemical formula A] Li １＋ｓ [Ni ｔ Co ｕ Mn Ｖ M １ ｗ ]O ２＋ｚ (In the above chemical formula A, M １ (where is one or more elements selected from W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and 0.05 ≤ s ≤ 1, 0 ≤ t ≤ 0.5, 0 ≤ u ≤ 0.3, 0.5 ≤ v < 1.0, 0 ≤ w ≤ 0.2, 0 ≤ z ≤ 1.)

3. The lithium secondary battery according to claim 1, wherein the compound represented by chemical formula 1 includes at least one selected from the group consisting of the compound represented by the following chemical formula 1-A and the compound represented by the following chemical formula 1-B. [Chemical formula 1-A] 【Transformation 3】 [Chemical formula 1-B] 【Chemistry 4】 (In the above chemical formulas 1-A and 1-B, R １ (This is the same as the definition in Chemical Formula 1 above.)

4. The lithium secondary battery according to claim 1, wherein the compound represented by chemical formula 1 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 1-1 to 1-9. [Chemical formula 1-1] 【Transformation 5】 [Chemical formula 1-2] 【Transformation 6】 [Chemical formula 1-3] 【Transformation 7】 [Chemical formula 1-4] 【Transformation 8】 [Chemical formula 1-5] 【Chemistry 9】 [Chemical formula 1-6] 【Chemistry 10】 [Chemical formula 1-7] 【Chemistry 11】 [Chemical formula 1-8] 【Chemistry 12】 [Chemical formula 1-9] 【Chemistry 13】

5. The lithium secondary battery according to claim 1, wherein the compound represented by chemical formula 1 is contained in an amount of 0.01% to 10% by weight, based on the weight of the non-aqueous electrolyte.

6. The lithium secondary battery according to claim 1, wherein the compound represented by chemical formula 2 includes at least one selected from the group consisting of compounds represented by the following chemical formulas 2-1 to 2-5. [Chemical formula 2-1] 【Chemistry 14】 [Chemical formula 2-2] 【Chemistry 15】 [Chemical formula 2-3] 【Chemistry 16】 [Chemical formula 2-4] 【Chemistry 17】 [Chemical formula 2-5] [Chemistry 18]

7. The lithium secondary battery according to claim 1, wherein the compound represented by chemical formula 2 is contained in the non-aqueous electrolyte in an amount of 5% to 40% by weight.

8. The lithium secondary battery according to claim 1, wherein the weight ratio of the compound represented by chemical formula 1 and the compound represented by chemical formula 2 is 0.01:99.1 to 50:

50.

9. The lithium salts mentioned above are LiCl, LiBr, LiI, and LiBF. ４ LiClO ４ LiAlO ４ LiAlCl ４ LiPF ６ LiSbF ６ LiAsF ６ LiB １０ Cl １０ , LiBOB(LiB(C ２ O ４ ) ２ ), LiCF ３ SO ３ , LiFSI (LiN(SO ２ F) ２ ), LiCH ３ SO ３ LiCF ３ CO ２ LiCH ３ CO ２ , and LiBETI(LiN(SO ２ CF ２ CF ３ ) ２ A lithium secondary battery according to claim 1, comprising at least one selected from the group consisting of ).

10. The non-aqueous electrolyte comprises an organic solvent, The lithium secondary battery according to claim 1, wherein the organic solvent comprises at least one selected from the group consisting of cyclic carbonate organic solvents, linear carbonate organic solvents, linear ester organic solvents, and cyclic ester organic solvents.

11. The lithium secondary battery according to claim 1, wherein the non-aqueous electrolyte further comprises at least one additive selected from the group consisting of vinylene carbonate, vinylethylene carbonate, fluoroethylene carbonate, propanesultone, propensultone, succinonitrile, adiponitrile, ethylene sulfate, LiBOB (Lithium bis-(oxalato)borate), LiODFB (Lithium difluoroooxalatoborate), TMSPa (Tris(trimethylsilyl phosphorate)), and TMSPi (Tris(trimethylsilyl) phosphorate).

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