Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The present disclosure relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same, wherein the electrolyte includes a non-aqueous organic solvent, a lithium salt, a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2. Chemical formula 1 and chemical formula 2

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0055507, filed on April 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Examples of this disclosure relate to electrolytes for rechargeable lithium batteries and rechargeable lithium batteries including electrolytes. Background Technology

[0004] Recently, with the increasing use of battery-powered electronic devices such as mobile phones, laptops, and electric vehicles, the demand for rechargeable lithium batteries with high energy density and high capacity has increased.

[0005] A rechargeable lithium battery typically includes a positive electrode, a negative electrode, and an electrolyte. The positive and negative electrodes each contain active materials capable of inserting and deintercalating lithium ions. When lithium ions are inserted into or deintercalated from the positive and negative electrodes, the rechargeable lithium battery generates electrical energy through oxidation and reduction reactions.

[0006] A solution of lithium salt dissolved in a non-aqueous organic solvent is used as the electrolyte in rechargeable lithium-ion batteries. Rechargeable lithium-ion batteries exhibit their characteristics through complex reactions between the positive electrode and the electrolyte, and between the negative electrode and the electrolyte. Therefore, the use of a suitable electrolyte is one of the important variables for improving the performance of rechargeable lithium-ion batteries. Summary of the Invention

[0007] This disclosure provides an electrolyte for rechargeable lithium batteries that has improved lifespan characteristics and stability at high temperatures.

[0008] This disclosure also provides rechargeable lithium batteries including electrolyte.

[0009] Example embodiments of this disclosure provide an electrolyte for a rechargeable lithium battery, the electrolyte comprising a non-aqueous organic solvent; a lithium salt; a first additive represented by chemical formula 1; and a second additive represented by chemical formula 2.

[0010] [Chemical Formula 1]

[0011]

[0012] [Chemical Formula 2]

[0013]

[0014] In chemical formula 1,

[0015] R1 to R6 are each independently hydrogen, an unsubstituted or substituted C1-C20 alkyl, an unsubstituted or substituted C1-C20 alkoxy, an unsubstituted or substituted C2-C20 alkenyl, an unsubstituted or substituted C2-C20 alkynyl, an unsubstituted or substituted C3-C20 cycloalkyl, an unsubstituted or substituted C6-C20 aryl, or an unsubstituted or substituted C2-C20 heteroaryl.

[0016] n is an integer equal to 0 or 1.

[0017] In chemical formula 2,

[0018] X1 can be a fluorine group, a chloro group, a bromine group, or an iodine group.

[0019] R7~R 12 Each of these elements is independently hydrogen, cyano, unsubstituted or substituted C1-C20 alkyl, unsubstituted or substituted C1-C20 alkoxy, unsubstituted or substituted C2-C20 alkenyl, unsubstituted or substituted C2-C20 alkynyl, unsubstituted or substituted C3-C20 cycloalkyl, unsubstituted or substituted C6-C20 aryl, or unsubstituted or substituted C2-C20 heteroaryl.

[0020] m is an integer equal to 0 or 1.

[0021] In an exemplary embodiment of this disclosure, a rechargeable lithium battery includes: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; and an electrolyte comprising a non-aqueous organic solvent; a lithium salt; the first additive represented by Chemical Formula 1; and the second additive represented by Chemical Formula 2. Attached Figure Description

[0022] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and form a part of this specification. The drawings illustrate exemplary embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure. In the drawings:

[0023] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to an exemplary embodiment of the present disclosure.

[0024] Figures 2-5 A schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Detailed Implementation

[0025] To fully understand the layout and effects of this disclosure, some exemplary embodiments of the disclosure will be described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the exemplary embodiments described below and can be implemented in various forms. Rather, exemplary embodiments are provided only to disclose this disclosure and to fully reveal the scope of this disclosure to those skilled in the art.

[0026] In this specification, it will be understood that when an element is referred to as being on another element, the element may be directly on the other element, or an intervening element may exist between the two. In the accompanying drawings, the dimensions (e.g., thickness) of some components are enlarged for the purpose of effectively explaining the technical content. Throughout the specification, the same reference numerals refer to the same elements.

[0027] Unless otherwise specified in this specification, singular expressions may include plural expressions. Additionally, unless otherwise specified, the phrase "A or B" may indicate "A but not B", "B but not A", and "A and B". The terms "comprises / includes" and / or "comprising / including" as used in this specification do not exclude the presence or addition of one or more other components.

[0028] In this specification, "combination thereof" may refer to mixtures, stacks, complexes, copolymers, alloys, blends and reaction products of the components.

[0029] In this specification, unless otherwise specified, “substitution” means that at least one hydrogen atom in a substituent or compound is substituted by: deuterium, halogen, hydroxyl, amino, C1-C30 amino, nitro, C1-C40 silyl, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C20 alkoxy, C1-C10 fluoroalkyl, cyano, or a combination thereof.

[0030] Specifically, "substitution" can mean that at least one hydrogen atom in a substituent or compound is substituted by: deuterium, halogroup, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C10 fluoroalkyl, or cyano. For example, "substitution" can mean that at least one hydrogen atom in a substituent or compound is substituted by: deuterium, halogroup, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. Furthermore, "substitution" can mean that at least one hydrogen atom in a substituent or compound is substituted by: deuterium, halogroup, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, or cyano. As an example, "substitution" may mean that at least one hydrogen atom in a substituent or compound is substituted with one of the following: deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl. Alkyl groups may include straight-chain alkyl groups and / or chain alkyl groups. Cycloalkyl groups may include cyclic alkyl groups. When the terms "about" or "substantially" are used in conjunction with numerical values ​​in this specification, they mean that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0031] Figure 1 This is a simplified conceptual diagram of a rechargeable lithium battery according to an exemplary embodiment of the present disclosure. (Reference) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0032] The positive electrode 10 and the negative electrode 20 may be separated from each other by a diaphragm 30. The diaphragm 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20 and the diaphragm 30 may be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20 and the diaphragm 30 may be immersed in the electrolyte ELL.

[0033] The electrolyte ELL may be or include a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move toward the positive electrode 10 or the negative electrode 20 through the separator 30.

[0034] Positive electrode 10

[0035] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 on the positive electrode current collector COL1. The positive electrode active material layer AML1 may include a positive electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0036] For example, the positive electrode 10 may further include components that can constitute a sacrificial positive electrode.

[0037] Based on a 100 wt% positive electrode active material layer AML1, the amount of positive electrode active material can be from about 90 wt% to about 99 wt%. Based on a 100 wt% positive electrode active material layer AML1, the amounts of binder and conductive material can be from about 0.5 wt% to about 5 wt%, respectively.

[0038] The binder is configured to sufficiently adhere the positive electrode active material particles to each other, and also to sufficiently adhere the positive electrode active material to the positive electrode current collector COL1. Examples of binders may include at least one of the following as non-limiting examples: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0039] Conductive materials can impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in the battery. Examples of conductive materials may include carbon-based materials (such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes); metallic materials containing at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0040] Al foil can be used as a positive electrode current collector COL1, but is not limited to this.

[0041] Positive electrode active material

[0042] The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiated intercalation compounds). For example, at least one of lithium and a composite oxide of at least one of a metal including at least one of cobalt, manganese and nickel may be used.

[0043] The composite oxide may be or include lithium transition metal composite oxides. Examples of lithium transition metal composite oxides may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, and cobalt-free nickel-manganese oxides.

[0044] As an example, the following compounds, represented by any of the following chemical formulas, can be used: Li a A 1-b X b O 2-c D c(0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8 and 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); or Li a FePO4 (0.90≤a≤1.8).

[0045] In the above chemical formula, A is or includes Ni, Co, Mn or a combination thereof; X is or includes Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D is or includes O, F, S, P or a combination thereof; G is or includes Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; and L 1 It may include Mn, Al, or combinations thereof.

[0046] Based on 100 mol% lithium-free metal in lithium transition metal composite oxides, the positive electrode active material can be, or include, for example, a high-nickel positive electrode active material with a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density rechargeable lithium batteries.

[0047] negative electrode 20

[0048] The negative electrode 20 for a rechargeable lithium battery may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 on the negative electrode current collector COL2. The negative electrode active material layer AML2 may include a negative electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0049] For example, the negative electrode active material layer AML2 may include about 90 wt% to about 99 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder and about 0 wt% to about 5 wt% of conductive material.

[0050] The binder can be configured to sufficiently adhere the negative electrode active material particles to each other, and also to sufficiently adhere the negative electrode active material to the negative electrode current collector COL2. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0051] Non-aqueous adhesives include or may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0052] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol.

[0053] When the aqueous binder is used as a binder in the negative electrode active material layer AML2, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts. The alkali metal may include Na, K, and Li.

[0054] Dry adhesives may be or include fibrous polymeric materials. For example, dry adhesives may be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyethylene oxide.

[0055] Conductive materials can impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in the battery. Non-limiting examples may include: carbon-based materials (such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes); metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0056] The negative electrode current collector COL2 may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, and a polymer substrate coated with a conductive metal.

[0057] Negative electrode active material

[0058] The negative electrode active material may include materials that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloys, materials that can be doped / dedoped with lithium, or transition metal oxides.

[0059] Materials capable of reversibly inserting / deintercalating lithium ions may include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Crystalline carbon may be or include graphite, such as amorphous, flake, sheet, spherical, or fibrous natural or artificial graphite. Amorphous carbon may be or include at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0060] The lithium metal alloy includes an alloy of lithium and a metal including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0061] The material capable of doping / dedoping lithium can be or include a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material can include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), at least one of Si-Q alloys (where Q includes at least one of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, and rare earth elements). The Sn-based negative electrode active material can at least include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), Sn-based alloys, or a combination thereof.

[0062] The silicon-carbon composite can be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite can be in the form of silicon particles and an amorphous carbon coating on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) in which primary silicon particles are aggregated and an amorphous carbon coating (shell) on the surface of the secondary particles. The amorphous carbon can also be between the primary silicon particles, and, for example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0063] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0064] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0065] Diaphragm 30

[0066] Depending on the type of rechargeable lithium battery, the separator 30 can be present between the positive electrode 10 and the negative electrode 20. The separator 30 can include at least one of a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more of its layers, such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.

[0067] The separator 30 can include a porous substrate and a coating on one or both surfaces of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0068] The porous substrate may be or include a polymer membrane formed from or comprising a copolymer or mixture of polymers or two or more of the following: polyolefins including at least one of polyethylene and polypropylene, polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., Teflon).

[0069] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0070] Inorganic materials may include, but are not limited to, inorganic particles containing at least one of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2 and boehmite.

[0071] Organic and inorganic materials can be mixed in a single coating, or coatings comprising organic materials and coatings comprising inorganic materials can be stacked.

[0072] Electrolyte ELL

[0073] Electrolytes (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0074] Non-aqueous organic solvents can serve as media for transporting ions that participate in the electrochemical reactions of a battery.

[0075] The non-aqueous organic solvent may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents.

[0076] Carbonate solvents may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0077] Ester solvents may include at least one of the following: methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0078] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include at least one of ethanol, isopropanol, etc., and aprotic solvents may include nitrile solvents (such as R-CN, where R is a C2-C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides (such as dimethylformamide); dioxolane (such as 1,3-dioxolane, 1,4-dioxolane, etc.); sulfolane, etc.

[0079] Non-aqueous organic solvents can be used alone or in combination with two or more solvents.

[0080] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed and used, and cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0081] Lithium salts dissolved in non-aqueous organic solvents supply lithium ions in batteries, ensuring basic operation of rechargeable lithium batteries and improving lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0082] Rechargeable lithium batteries

[0083] Rechargeable lithium batteries can be classified according to their shape as cylindrical, prismatic, pouch, or coin-shaped batteries, etc. Figures 2-5 A schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 A pouch-type battery is shown. (Reference) Figures 2-5The rechargeable lithium battery 100 may include an electrode assembly 40 (including a separator 30 between a positive electrode 10 and a negative electrode 20) and a housing 50 (including the electrode assembly 40). The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of a sealed housing 50. Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include Figure 5 The electrode terminal 70 described herein can be, for example, in... Figure 4 The positive electrode terminal 71 and negative electrode terminal 72, as illustrated in the diagram, form an electrical path for guiding the current generated in the electrode assembly 40 to the outside of the battery 100.

[0084] The electrolyte of a rechargeable lithium battery according to an exemplary embodiment of the present disclosure will be described in more detail below.

[0085] An electrolyte for a rechargeable lithium battery according to an example embodiment may include a non-aqueous organic solvent, a salt (such as a lithium salt), a first additive represented by the following chemical formula 1, which will be described later, and a second additive represented by the following chemical formula 2, which will be described later.

[0086] Electrolytes can be prepared by a mixing process in which lithium salts are dissolved in a non-aqueous organic solvent, and a first additive and a second additive are added and mixed. The process of mixing electrolytes is known in the field of electrolyte preparation, and those skilled in the art can appropriately select and use it.

[0087] Non-aqueous organic solvents may include at least one of ethylene carbonate (EC), propylene carbonate (PC), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), and butyl carbonate (BC).

[0088] In an example embodiment, the non-aqueous organic solvent may be or include a mixture of solvents containing at least ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC).

[0089] As an example, based on the total amount of non-aqueous organic solvents, the content of ethylene carbonate (EC) can be from about 10 vol% to about 30 vol%. Based on the total amount of non-aqueous organic solvents, the content of ethyl methyl carbonate (EMC) can be from about 5 vol% to about 20 vol%. Based on the total amount of non-aqueous organic solvents, the content of dimethyl carbonate (DMC) can be from about 50 vol% to about 80 vol%.

[0090] The lithium salt may include at least one selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI)), and LiC4F9SO3. According to an example embodiment, LiPF6 may be used as the lithium salt.

[0091] The lithium salt can have a concentration of about 0.1 M to about 2.0 M. Specifically, the lithium salt can have a concentration of about 0.5 M or higher, or about 1.0 M. The lithium salt can have a concentration of about 2.0 M or lower, about 1.7 M or lower, or about 1.5 M or lower. In this disclosure, when the lithium salt has a concentration of about 0.1 M to about 2.0 M, the conductivity and viscosity of the electrolyte can be appropriately maintained.

[0092] First Additive

[0093] The first additive according to the example of this disclosure can be represented by the following chemical formula 1:

[0094] [Chemical Formula 1]

[0095]

[0096] In chemical formula 1,

[0097] R1 to R6 may each be independently hydrogen, unsubstituted or substituted C1 to C20 alkyl, unsubstituted or substituted C1 to C20 alkoxy, unsubstituted or substituted C2 to C20 alkenyl, unsubstituted or substituted C2 to C20 alkynyl, unsubstituted or substituted C3 to C20 cycloalkyl, unsubstituted or substituted C6 to C20 aryl, or unsubstituted or substituted C2 to C20 heteroaryl.

[0098] In Formula 1, n can be an integer equal to 0 or 1. When n equals 0, the bond between R3 / R4 and R5 / R6 can be a direct bond (i.e., a single bond). For example, when n equals 0, the cyclic phosphoric cyclopentane derivative containing the -OPO- functional group can have a pentagonal ring.

[0099] In the example implementation, chemical formula 1 may be represented by chemical formula 1A or chemical formula 1B:

[0100]

[0101] In chemical formula 1A and chemical formula 1B,

[0102] R1 to R6 can each be independently hydrogen, unsubstituted or substituted C1 to C10 alkyl, unsubstituted or substituted C1 to C10 alkoxy, unsubstituted or substituted C2 to C10 alkenyl, or unsubstituted or substituted C2 to C10 alkynyl.

[0103] In the example embodiment, R3 and R4 in Formula 1A may each be hydrogen, and at least one of R5 and R6 may be an unsubstituted or substituted C1-C10 alkyl, an unsubstituted or substituted C1-C10 alkoxy, an unsubstituted or substituted C2-C10 alkenyl, or an unsubstituted or substituted C2-C10 alkynyl.

[0104] In an exemplary embodiment, the first additive represented by Formula 1 may be or include at least one of the compounds listed in Group 1 below. That is, the first additive may be or include at least one of 1-(1,3,2-dioxaphosphacyclopentan-2-yl)-1H-1,2,4-triazole and 1-(4-methyl-1,3,2-dioxaphosphacyclopentan-2-yl)-1H-1,2,4-triazole:

[0105] [Group 1]

[0106]

[0107] In an example embodiment, the first additive represented by chemical formula 1 may be or include compounds of chemical formula 1A-1:

[0108] [Chemical Formula 1A-1]

[0109]

[0110] The content of the first additive may be from about 0.01 wt% to about 10 wt%, depending on the total amount of electrolyte. For example, the amount of the first additive may be in the range of about 0.5 wt% to about 5 wt%, depending on the total amount of electrolyte.

[0111] The amount of additive, based on the total amount of electrolyte, indicates the weight of the additive contained in the electrolyte. When the amount of additive meets the above range, it is possible to reduce or suppress the increase in resistance and reduce gas generation at high temperatures.

[0112] The first additive, represented by Formula 1, may contain a -OPO- functional group. The -OPO- functional group can reduce gas generation in the battery by stabilizing the thermal decomposition products of lithium salts or anions dissociated from lithium salts. For example, the -OPO- functional group can reduce HF gas generation by stabilizing PF5 produced during the thermal decomposition of LiPF6.

[0113] The -OPO- functional group contained in the first additive can be derived from cyclic phosphacene pentanes. Compared with straight-chain phosphite derivatives, cyclic phosphacene pentane derivatives can significantly improve the life characteristics of rechargeable lithium batteries at high temperatures. Straight-chain phosphite derivatives may not be suitable for high temperatures because they generate gas due to the decomposition reaction of the electrolyte during high-temperature storage, which is caused by the side reaction of LiPF6 due to the dissociation of the -PO2- functional group.

[0114] The first additive may contain a triazole functional group (i.e., a triazole group). The triazole group is a highly polar compound, and since the triazole group has high solubility in electrolytes using polar solvents (such as ethylene carbonate), it can be advantageously used as an additive in rechargeable lithium batteries.

[0115] Furthermore, the lone pair electrons of the nitrogen (N) group in the triazole functional group can stabilize Lewis acids (e.g., PF5) by acting on them in the electrolyte. This reduces the continuous decomposition reaction of the lithium salt, thereby reducing or preventing the electrolyte from becoming an acidic environment. The lone pair electrons of the triazole group can also stabilize transition metals on and released from the positive electrode surface. This can improve battery life by reducing or preventing the degradation of the positive electrode.

[0116] The triazole group may be or include an amphoteric substance that can act as an acid or a base. The acidity of the triazole group may originate from the -NH group and may lead to battery degradation. In the additives of the examples according to this disclosure, the nitrogen (N) in the triazole group is directly linked to phosphorus (P) via a covalent bond. In this case, since the -NH group of the triazole group is removed, only the basicity of the triazole group can be effectively utilized.

[0117] Because the first additive according to the exemplary embodiments of this disclosure contains both -OPO- functional groups and triazole functional groups, the first additive may have the positive effects of reducing or inhibiting the increase in resistance and reducing gas.

[0118] When the first additive is used in conjunction with high-nickel positive electrode active materials and negative electrode active materials including silicon-carbon composites, the effect of the first additive, represented by Chemical Formula 1, on improving the high-temperature stability of rechargeable lithium batteries is more significant. For example, silicon particles increase battery capacity, but they can also increase the battery's internal resistance by causing side reactions with the electrolyte. Because the first additive reduces or inhibits side reactions between silicon particles and the electrolyte, it can achieve or maximize the increase in battery capacity while reducing or minimizing the increase in battery internal resistance.

[0119] Second additive

[0120] The second additive according to the example of this disclosure can be represented by the following chemical formula 2:

[0121] [Chemical Formula 2]

[0122]

[0123] In chemical formula 2,

[0124] X1 can be a fluorine group, a chloro group, a bromine group, or an iodine group.

[0125] R7~R 12 Each of these elements is independently hydrogen, cyano, unsubstituted or substituted C1-C20 alkyl, unsubstituted or substituted C1-C20 alkoxy, unsubstituted or substituted C2-C20 alkenyl, unsubstituted or substituted C2-C20 alkynyl, unsubstituted or substituted C3-C20 cycloalkyl, unsubstituted or substituted C6-C20 aryl, or unsubstituted or substituted C2-C20 heteroaryl.

[0126] m can be an integer equal to 0 or 1. When m equals 0, R9 / R 10 With R 11 / R 12 The bonds between them can be direct bonds. For example, when m equals 0, the cyclic phosphoric pentane derivative containing the -OPO- functional group can have a pentagonal ring moiety.

[0127] Chemical formula 2 can be represented by chemical formula 2A or chemical formula 2B.

[0128]

[0129]

[0130] In chemical formulas 2A and 2B,

[0131] X1 is a fluorine, chloro, bromine, or iodine group, and

[0132] R7~R 12Each of them can be independently hydrogen, unsubstituted or substituted C1-C10 alkyl, unsubstituted or substituted C1-C10 alkoxy, unsubstituted or substituted C2-C10 alkenyl, or unsubstituted or substituted C2-C10 alkynyl.

[0133] As an example, chemical formula 2 can be represented by chemical formula 2A. R9 and R in chemical formula 2A... 10 Each is hydrogen, and R 11 and R 12 At least one of them may be an unsubstituted or substituted C1-C10 alkyl, an unsubstituted or substituted C1-C10 alkoxy, an unsubstituted or substituted C2-C10 alkenyl, or an unsubstituted or substituted C2-C10 alkynyl. Furthermore, R9 and R in formula 2A... 10 R 11 and R 12 Each can be hydrogen.

[0134] As an example, the second additive represented by chemical formula 2 may be or include at least one of the compounds listed in group 2 below, and, for example, may be or include at least one of 2-fluoro-1,3,2-dioxophosphazenecyclopentane and 2-fluoro-4-methyl-1,3,2-dioxophosphazenecyclopentane.

[0135] [Group 2]

[0136]

[0137] In an example embodiment, the second additive represented by chemical formula 2 may be or include compounds of chemical formula 2A-1:

[0138] [Chemical Formula 2A-1]

[0139]

[0140] The content of the second additive can be from about 0.01 wt% to about 5 wt%, depending on the total amount of electrolyte. For example, the amount of the second additive can be in the range of about 0.5 wt% to about 2 wt%, depending on the total amount of electrolyte. When the amount of the second additive is in the range described above, a rechargeable lithium battery with improved life characteristics and output characteristics at high temperatures can be realized.

[0141] The second additive forms a solid electrolyte interface (SEI) on the surface of the negative electrode, which has increased high-temperature stability and desired or improved ionic conductivity. It can also reduce the gases generated during high-temperature storage due to electrolyte decomposition reactions by reducing or suppressing side reactions of LiPF6 caused by the -PO2F functional group.

[0142] In the example, the second additive can form a complex by coordinating with the thermal decomposition products of lithium salts (such as LiPF6) or anions dissociated from lithium salts. By stabilizing the thermal decomposition products of lithium salts or anions dissociated from lithium salts due to the formation of the complex, unwanted side reactions between them and the electrolyte can be reduced or suppressed.

[0143] Accordingly, in addition to improving the cycle life characteristics of rechargeable lithium batteries, reducing or preventing the generation of gas in rechargeable lithium batteries can significantly improve high-temperature storage characteristics and significantly reduce the defect rate.

[0144] A synergistic effect can occur when the first additive is used in combination with an additive having a structure containing a -PO2F functional group (e.g., the second additive described above). The combination of the first and second additives can not only reduce or suppress gas generation in lithium batteries and improve the high-temperature storage performance of the batteries, but also improve the high-temperature cycling and room-temperature cycling stability of the batteries.

[0145] For example, since the electrolyte according to the example of this disclosure has the effect of reducing or suppressing the increase in battery internal resistance by reducing or preventing the degradation of the positive electrode caused by the triazole group present in the first additive, and the effect of reducing gas generation caused by the -PO2F functional group present in the second additive, it can effectively improve the life characteristics and stability of rechargeable lithium batteries under high temperature conditions during activation.

[0146] As an example, the amount of the first additive in the electrolyte can be greater than the amount of the second additive. The ratio of the amount of the first additive to the amount of the second additive can be in the range of about 1 to about 10. According to the example embodiment, the ratio of the amount of the first additive to the amount of the second additive can be in the range of about 1 to about 6. When the ratio of the amount of the first additive to the amount of the second additive is less than the above range, the effect of reducing or suppressing the increase in resistance at high temperatures may not be significant, and when the ratio of the amount of the first additive to the amount of the second additive is greater than the above range, the lifespan and efficiency of the rechargeable lithium battery may decrease rapidly.

[0147] Another exemplary embodiment of this disclosure includes a rechargeable lithium battery comprising: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte, wherein the electrolyte comprises a non-aqueous organic solvent, a lithium salt, the first additive represented by chemical formula 1 and the second additive represented by chemical formula 2.

[0148] As a non-limiting example, rechargeable lithium batteries can be used in, for example, automobiles, mobile phones and / or various types of electronic devices.

[0149] The positive electrode active material may include lithium composite oxides represented by the following chemical formula 3.

[0150] [Chemical Formula 3]

[0151] Li x M 1 y M 2 z M 3 1-y-z O 2-a X a

[0152] Where 0.5≤x≤1.8, 0≤a≤0.05, 0≤y≤1, 0≤z≤1, and 0≤y+z≤1.

[0153] M 1 M 2 and M 3 Each of these elements can independently include one or more elements selected from metals such as nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), boron (B), barium (Ba), calcium (Ca), cerium (Ce), chromium (Cr), iron (Fe), molybdenum (Mo), niobium (Nb), silicon (Si), strontium (Sr), magnesium (Mg), titanium (Ti), vanadium (V), tungsten (W), yttrium (Y), zirconium (Zr), and lanthanum (La).

[0154] X may include at least one of fluorine (F), sulfur (S), phosphorus (P), and chlorine (Cl).

[0155] In the example implementation, in chemical formula 3, M 1 It can be or include Ni, 0.8 ≤ y ≤ 1, and 0 ≤ z ≤ 0.2. Furthermore, in chemical formula 3, M... 1 It may be or include Ni, M 2 It may be or include Co, and M 3 It can be or include Al. Furthermore, in chemical formula 3, M... 1 It may be or include Ni, M 2 It may be or include Co, and M 3 It can be or include Mn.

[0156] In an example embodiment, the positive electrode active material of the rechargeable lithium battery may include at least one of nickel, cobalt, and aluminum. Furthermore, in an example embodiment, the positive electrode active material of the rechargeable lithium battery may include at least one of nickel, cobalt, and manganese.

[0157] Carbon-based negative electrode active materials, Sn-based negative electrode active materials, silicon-based negative electrode active materials, or combinations thereof can be used as negative electrode active materials for rechargeable lithium batteries.

[0158] In an example implementation, the silicon-based negative electrode active material may be or include a silicon-carbon composite.

[0159] The silicon-based negative electrode active material may include a core containing silicon-based particles and a coating containing amorphous carbon. The silicon-based particles may include at least one of silicon particles, Si-C composites, SiO x (0 < x ≤ 2) and Si alloys.

[0160] When the positive electrode includes a high-nickel positive electrode active material and the negative electrode includes a silicon-carbon composite, the effect of improving the high-temperature stability of the rechargeable lithium battery can be achieved or maximized. The rechargeable lithium battery having the above composition can even be operated at a high voltage of about 4.2 V or higher.

[0161] The following examples and comparative examples are provided to highlight the characteristics of one or more exemplary embodiments, but it will be understood that the examples and comparative examples are not to be construed as limiting the scope of the exemplary embodiments, nor should the comparative examples be construed as exceeding the scope of the exemplary embodiments. Further, it will be understood that the exemplary embodiments are not limited to the specific details described in the examples and comparative examples.

[0162] Examples and Comparative Examples

[0163] Example 1

[0164] (1) Preparation of electrolyte

[0165] 1.5 M LiPF6 was dissolved in a non-aqueous organic solvent (where ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of about 20:10:70), and about 0.5 wt% of a first additive and about 0.5 wt% of a second additive based on the total weight of the electrolyte were added to prepare the electrolyte.

[0166] The compound represented by Chemical Formula 2A-1 was used as the second additive:

[0167] [Chemical Formula 2A-1]

[0168]

[0169] The compound represented by Chemical Formula 1A-1 was used as the first additive:

[0170] Specifically, the first additive according to Chemical Formula 1A-1 can be prepared by the following synthesis example.

[0171] Synthesis Example

[0172] A petroleum ether solution (51 mL) containing approximately 11.53 g (0.0821 mol) of 2-chloro-4-methyl-1,3,2-dioxophosphazenecyclopentane was added dropwise to a petroleum ether solution (51 mL) containing approximately 5.61 g (0.04 mol) of 1-(trimethylsilyl)-1H-triazole, and the mixture was stirred at room temperature (25 °C) for approximately 10 minutes under an inert atmosphere. After stirring for approximately 24 hours to evaporate the volatile components of the reaction mixture, the residue was fractionally distilled at approximately 90 °C under a vacuum of approximately 2 Torr to obtain the compound represented by chemical formula 1A-1:

[0173] [Chemical Formula 1A-1]

[0174]

[0175] (2) Manufacturing of rechargeable lithium batteries

[0176] LiNi will be used as the active material for the positive electrode. 0.91 Co 0.07 Al 0.02 O2, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material are mixed in a weight ratio of approximately 97:2:1 and dispersed in N-methylpyrrolidone to prepare a slurry for positive electrode active materials.

[0177] The positive electrode active material slurry was applied to an aluminum current collector with a thickness of about 14 μm, dried at about 110 °C, and then pressed to prepare the positive electrode.

[0178] A mixture of artificial graphite and silicon nanoparticles in a weight ratio of approximately 93:7, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose (CMC) as a tackifier were mixed in a weight ratio of approximately 97:1:2 and dispersed in distilled water to prepare a slurry of negative electrode active material.

[0179] The negative electrode active material slurry was applied onto a copper current collector approximately 10 μm thick, dried at approximately 100 °C, and then pressed to prepare the negative electrode.

[0180] An electrode assembly is fabricated by assembling a positive electrode, a negative electrode, and a polyethylene separator approximately 25 μm thick, and an electrolyte is injected to create a rechargeable lithium battery.

[0181] Example 2

[0182] The electrolyte and rechargeable lithium battery were prepared in essentially the same manner as in Example 1, except that about 1 wt% of a first additive was used.

[0183] Example 3

[0184] The electrolyte and rechargeable lithium battery were prepared in essentially the same manner as in Example 1, except that about 3 wt% of a first additive was used.

[0185] Example 4

[0186] The electrolyte and rechargeable lithium battery were prepared in essentially the same manner as in Example 1, except that about 5 wt% of a first additive and about 2 wt% of a second additive were used.

[0187] Comparative Example 1

[0188] The rechargeable lithium battery was prepared in essentially the same manner as in Example 1, except that no additives were used during electrolyte preparation.

[0189] Comparative Example 2

[0190] The electrolyte and rechargeable lithium battery were prepared in essentially the same manner as in Example 1, except that no first additive was added during the preparation of the electrolyte.

[0191] Evaluation Example

[0192] The rechargeable lithium battery was evaluated in the following manner.

[0193] Evaluation 1: Resistance Test

[0194] The rechargeable lithium batteries manufactured in the Examples and Comparative Examples were charged to approximately 4.25V at approximately 25°C. The initial resistance of each rechargeable lithium battery and the resistance of each rechargeable lithium battery after approximately 60 days at approximately 55°C were measured. The rate of increase in resistance was calculated, and the results are shown in Table 1 below. The resistance was measured using electrochemical impedance spectroscopy (EIS).

[0195] The resistance value is calculated using a DC-IR measurement method, which uses current and voltage values ​​obtained by discharging each rechargeable lithium battery at approximately 1C for about 30 seconds at a state of charge (SOC 50).

[0196] Calculate the rate of increase in resistance using Equation 1 below.

[0197] [Equation 1]

[0198] Resistance increase rate (%) = ((resistance value of rechargeable lithium battery after 60 days / initial resistance value of rechargeable lithium battery) - 1) × 100

[0199] Assessment 2: Assessment of High-Temperature Gas Generation Characteristics

[0200] The high-temperature gas generation characteristics of the rechargeable lithium batteries according to the embodiments and comparative examples were evaluated. For this purpose, the rechargeable lithium batteries according to the embodiments and comparative examples were charged to approximately 4.25V at approximately 25°C and then left to stand at approximately 55°C for approximately 60 days.

[0201] The amount of gas produced by a rechargeable lithium battery after being left to stand for approximately 60 days was measured, and the results are shown in Table 1 below.

[0202] [Table 1]

[0203]

[0204] Comprehensive assessment

[0205] Referring to Table 1, it can be confirmed that, compared with the case of using an electrolyte without any additives (Comparative Example 1) and the case of using only the second additive (Comparative Example 2), when using an electrolyte in which the first additive and the second additive according to the concept of this disclosure are added (Examples 1 to 4), the increase in resistance and gas generation at high temperature (60°C) are reduced or suppressed more effectively.

[0206] By combining a first additive containing a triazole group and a second additive containing a -PO2F functional group, the electrolyte according to the example embodiment can exhibit improved lifetime characteristics and stability under high-temperature conditions during rechargeable lithium battery activation.

[0207] Although exemplary embodiments of this disclosure have been described above, the scope of this disclosure is not limited to the exemplary embodiments. Various modifications may be made to the exemplary embodiments without departing from the spirit and scope of this disclosure as defined by the claims, and such modifications are included within the scope of this disclosure.

Claims

1. An electrolyte for a rechargeable lithium battery, the electrolyte comprising: Non-aqueous organic solvents; Lithium salts; The first additive represented by chemical formula 1; and The second additive represented by chemical formula 2: Chemical Formula 1 Chemical formula 2 In chemical formula 1, R1 to R6 are each independently hydrogen, an unsubstituted or substituted C1-C20 alkyl, an unsubstituted or substituted C1-C20 alkoxy, an unsubstituted or substituted C2-C20 alkenyl, an unsubstituted or substituted C2-C20 alkynyl, an unsubstituted or substituted C3-C20 cycloalkyl, an unsubstituted or substituted C6-C20 aryl, or an unsubstituted or substituted C2-C20 heteroaryl. n is an integer equal to 0 or 1. In chemical formula 2, X1 can be a fluorine group, a chloro group, a bromine group, or an iodine group. R7~R 12 Each of these elements is independently hydrogen, cyano, unsubstituted or substituted C1-C20 alkyl, unsubstituted or substituted C1-C20 alkoxy, unsubstituted or substituted C2-C20 alkenyl, unsubstituted or substituted C2-C20 alkynyl, unsubstituted or substituted C3-C20 cycloalkyl, unsubstituted or substituted C6-C20 aryl, or unsubstituted or substituted C2-C20 heteroaryl. m is an integer equal to 0 or 1.

2. The electrolyte for a rechargeable lithium battery as described in claim 1, wherein chemical formula 1 is represented by chemical formula 1A or chemical formula 1B: in, In chemical formula 1A and chemical formula 1B, R1 to R6 are each independently hydrogen, unsubstituted or substituted C1 to C10 alkyl, unsubstituted or substituted C1 to C10 alkoxy, unsubstituted or substituted C2 to C10 alkenyl, or unsubstituted or substituted C2 to C10 alkynyl.

3. The electrolyte for a rechargeable lithium battery as described in claim 2, wherein R3 and R4 in chemical formula 1A are each hydrogen, and At least one of R5 and R6 is an unsubstituted or substituted C1-C10 alkyl, an unsubstituted or substituted C1-C10 alkoxy, an unsubstituted or substituted C2-C10 alkenyl, or an unsubstituted or substituted C2-C10 alkynyl.

4. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the first additive represented by chemical formula 1 comprises at least one of the compounds listed in group 1: Group 1 5. The electrolyte for a rechargeable lithium battery as described in claim 1, wherein chemical formula 2 is represented by chemical formula 2A or chemical formula 2B: in, In chemical formulas 2A and 2B, X1 is a fluorine, chloro, bromine, or iodine group, and R7~R 12 Each of them is independently hydrogen, unsubstituted or substituted C1-C10 alkyl, unsubstituted or substituted C1-C10 alkoxy, unsubstituted or substituted C2-C10 alkenyl, or unsubstituted or substituted C2-C10 alkynyl.

6. The electrolyte for a rechargeable lithium battery as described in claim 5, wherein, In chemical formula 2A, R9 and R 10 Each is hydrogen, and R 11 and R 12 At least one of them is an unsubstituted or substituted C1-C10 alkyl, an unsubstituted or substituted C1-C10 alkoxy, an unsubstituted or substituted C2-C10 alkenyl, or an unsubstituted or substituted C2-C10 alkynyl.

7. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the second additive represented by chemical formula 2 comprises at least one of the compounds listed in group 2: Group 2 8. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the amount of the first additive is in the range of 0.01 wt% to 10 wt% based on the total weight of the electrolyte.

9. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the amount of the second additive is in the range of 0.01 wt% to 5 wt% based on the total weight of the electrolyte.

10. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the ratio of the first additive represented by chemical formula 1 to the second additive represented by chemical formula 2 is in the range of 1 to 6.

11. The electrolyte for a rechargeable lithium battery as described in claim 1, wherein: The non-aqueous organic solvent includes carbonate solvents, and The carbonate solvents include at least one of ethylene carbonate, propylene carbonate, propyl propionate, methyl ethyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, and butyl carbonate.

12. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the lithium salt comprises at least one of the following: LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, LiC4F9SO3, lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate, lithium difluorobis(oxalate)phosphate, lithium bis(oxalate)borate, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), where x and y are integers from 1 to 20.

13. The electrolyte for a rechargeable lithium battery as claimed in claim 1, wherein the lithium salt has a concentration of 0.1M to 2.0M.

14. A rechargeable lithium battery, comprising: Positive electrode, including positive electrode active material; The negative electrode includes the negative electrode active material; and The electrolyte as described in any one of claims 1 to 13.

15. The rechargeable lithium battery of claim 14, wherein the positive electrode active material comprises a lithium composite oxide represented by chemical formula 3: Chemical formula 3 Li x M 1 y M 2 z M 3 1-y-z O 2-a X a Where 0.5≤x≤1.8, 0≤a≤0.05, 0≤y≤1, 0≤z≤1, and 0≤y+z≤1. M 1 M 2 and M 3 Each independently comprises one or more metals including at least Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Y, Zr, and La, and X includes at least one of F, S, P, and Cl.

16. The rechargeable lithium battery of claim 15, wherein, In chemical formula 3, M 1 For Ni, 0.8≤y≤1 and 0≤z≤0.

2.

17. The rechargeable lithium battery of claim 14, wherein the negative electrode active material comprises at least one of carbon-based negative electrode active materials, Sn-based negative electrode active materials, and silicon-based negative electrode active materials.

18. The rechargeable lithium battery of claim 14, wherein the rechargeable lithium battery is configured to operate at a high voltage of 4.2V or higher.

Images