Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte. An electrolyte for a rechargeable lithium battery may include a non-aqueous organic solvent, a lithium salt, and an additive. The non-aqueous organic solvent may include a first compound represented by Formula 1. The additive may include a second compound represented by Formula 2. The description about the above Formula 1 and Formula 2 is as described in the specification. [Formula 1] [Formula 2]

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0131854, filed on September 27, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates herein to electrolytes for rechargeable lithium batteries and rechargeable lithium batteries including electrolytes. Background Technology

[0004] Recently, with the rapid proliferation of battery-powered electronic devices (such as mobile phones, laptops, and / or electric vehicles), the demand for rechargeable batteries with high energy density and high capacity has increased rapidly. Accordingly, research and development have been actively undertaken to improve the performance of rechargeable batteries (such as rechargeable lithium batteries).

[0005] A rechargeable lithium battery includes a positive electrode and a negative electrode, each containing active materials capable of intercalating and deintercalating lithium ions, and an electrolyte. Electrical energy is generated through oxidation and reduction reactions when lithium ions intercalate and deintercalate between the positive and negative electrodes (e.g., when).

[0006] Electrolytes used in rechargeable lithium-ion batteries consist of lithium salts dissolved in non-aqueous organic solvents. Rechargeable lithium-ion batteries exhibit battery characteristics (e.g., generating electricity) through complex reactions between the positive electrode and the electrolyte, and / or between the negative electrode and the electrolyte. Therefore, utilizing a suitable or appropriate electrolyte is one of the important variables that can improve the performance of rechargeable lithium-ion batteries. Summary of the Invention

[0007] One or more aspects of the present disclosure relate to electrolytes for rechargeable lithium batteries capable of enhancing (e.g., improving) the battery's lifespan characteristics and stability.

[0008] One or more aspects of the present disclosure relate to rechargeable lithium batteries including an electrolyte.

[0009] Other aspects will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of embodiments of this disclosure.

[0010] According to one or more embodiments, the electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent, a lithium salt, and an additive. The non-aqueous organic solvent may include a first compound represented by Formula 1. The additive may include a second compound represented by Formula 2.

[0011] [Formula 1]

[0012]

[0013] In Equation 1,

[0014] R 1 It can be a substituted or unsubstituted C1-C6 alkyl group, or a substituted or unsubstituted C1-C12 aryl group, and

[0015] R 2 It can be a direct bond or a C1-C6 alkylene group, and [Formula 2]

[0016]

[0017] In Equation 2, n can be an integer from 1 to 8 (for example, n can be 1, 2, 3, 4, 5, 6, 7, or 8), and

[0018] The electrolyte can be the same electrolyte used in rechargeable lithium batteries.

[0019] According to one or more embodiments, a rechargeable lithium battery may include: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and the aforementioned electrolyte. Attached Figure Description

[0020] 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 embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the drawings:

[0021] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure;

[0022] Figure 2 A schematic diagram illustrating one or more embodiments of a cylindrical battery according to this disclosure;

[0023] Figure 3 A schematic diagram illustrating one or more embodiments of the prismatic battery according to this disclosure;

[0024] Figure 4 Schematic diagram illustrating a pouch-type (or similar) battery according to one or more embodiments of the present disclosure; and

[0025] Figure 5 A schematic diagram illustrating a pouch-type (or similar) battery according to one or more embodiments of the present disclosure. Detailed Implementation

[0026] To fully understand the configuration and effects of this disclosure, embodiments thereof will be described in more detail with reference to the accompanying drawings. However, this disclosure may be implemented in one or more suitable forms and should not be construed as limited to the embodiments set forth herein, and one or more suitable changes and modifications may be made. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art to which it pertains.

[0027] In this specification, it will be understood that if (e.g., when) an element is referred to as being "on" another element, then the element may be directly on the other element, or an intervening element may be present between them. In the accompanying drawings, the dimensions (e.g., thickness) of components may be enlarged for effective explanation of the technical content. The same reference numerals or symbols refer to the same elements throughout the document and their repeated description may not be provided in the specification.

[0028] Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Additionally, unless otherwise specifically indicated, the phrases “A or B” and “A and / or B” may indicate inclusion of “A but not B,” “B but not A,” or “A and B.” The terms “comprises” and / or “comprising” as used in this specification do not exclude the presence or addition of one or more other components.

[0029] In this specification, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, and / or reaction product of the components.

[0030] In this specification, unless otherwise specified, particle size may refer to the average particle size. Furthermore, particle size refers to the average particle size (D). 50 ), average particle size (D 50 The average particle size (D) refers to the diameter of particles that constitute approximately 50% of the total volume in the particle size distribution. 50 The average particle size can be measured by any suitable method (e.g., methods known to those skilled in the art), such as by a particle size analyzer, or by using transmission electron microscopy (TEM) images or scanning electron microscopy (SEM) images. In one or more embodiments, the average particle size is measured using a dynamic light-scattering measurement device, wherein the number of particles is counted for each particle size range by performing data analysis, and then the average particle size (D) can be calculated based on the obtained data. 50The average particle size can be measured using laser diffraction. When measured by laser diffraction, the particles to be measured are dispersed in a dispersion medium, which is then introduced into a commercial laser diffraction particle size analyzer (e.g., MicrotracMT 3000). TM The sample is irradiated with ultrasound at approximately 28 kHz with an output power of approximately 60 W, and the average particle size (D) can then be calculated in the measuring instrument based on approximately 50 vol% of the particle size distribution. 50 In this specification, when the particles are spherical, "diameter" or "size" indicates the particle size, and when the particles are non-spherical, "diameter" or "size" indicates the length of the major axis.

[0031] In this specification, unless otherwise specified, the term "substitution" means that at least one hydrogen atom of 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, and / or combinations thereof (e.g., any suitable combination).

[0032] In one or more embodiments, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: 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, and / or cyano. For example, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: deuterium, halogroup, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, and / or cyano. In one or more embodiments, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: deuterium, halogroup, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, and / or cyano. For example, the term "substitution" can refer to the substitution of at least one hydrogen atom of a substituent or compound by the following: deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, and / or naphthyl.

[0033] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of this disclosure. (See reference...) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0034] The positive electrode 10 and the negative electrode 20 may be spaced apart and / or separated from each other (e.g., spaced apart and / or separated) by a diaphragm 30 therebetween. 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.

[0035] The electrolyte ELL can be used as a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move towards the positive electrode 10 or the negative electrode 20 through the separator 30.

[0036] Positive electrode 10

[0037] 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 formed 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 conductor).

[0038] Based on a 100 wt% positive electrode active material layer AML1, the amount of positive electrode active material in the positive electrode active material layer AML1 can be from about 90 wt% to about 99 wt%. Based on a 100 wt% positive electrode active material layer AML1, the amount of each of the binder and conductive material can be from about 0.5 wt% to about 5 wt%.

[0039] The adhesive is used to adhere the positive electrode active material particles well or suitably to each other and also to adhere the positive electrode active material well or suitably to the positive electrode current collector COL1. Non-limiting examples of adhesives may include acrylonitrile-butadiene rubber, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0040] Conductive materials can be used to 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 a battery. Examples of conductive materials may include: carbon-based materials (such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and / or carbon nanotubes); metallic materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., any suitable mixture).

[0041] Aluminum (Al) foil can be used as the positive electrode current collector COL1, but this disclosure is not limited thereto.

[0042] Positive electrode active material

[0043] The positive electrode active material in the positive electrode active material layer AML1 may include compounds capable of reversibly inserting and deintercalating lithium ions (lithiation intercalation compounds). For example, a composite oxide of at least one lithium and a metal selected from cobalt, manganese, nickel and / or one or more combinations thereof (e.g., any suitable combination) may be used.

[0044] The composite oxide may be a lithium transition metal composite oxide. Non-limiting examples of composite oxides may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free nickel manganese oxides, and / or combinations thereof (e.g., any suitable combination).

[0045] As an example, a compound represented by any of the following chemical formulas (e.g., selected from 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); Lia 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); and Li a FePO4 (0.90≤a≤1.8).

[0046] In the above chemical formulas, A is Ni, Co, Mn and / or combinations thereof (e.g., any suitable combination); X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and / or combinations thereof (e.g., any suitable combination); D is O, F, S, P and / or combinations thereof (e.g., any suitable combination); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or combinations thereof (e.g., any suitable combination); and L 1 Mn, Al, and / or combinations thereof (e.g., any suitable combination).

[0047] The positive electrode active material can be, for example, a high-nickel positive electrode active material based on 100 mol% of all metals excluding lithium in a lithium transition metal complex oxide, with a nickel content (e.g., amount) 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 used in high-capacity, high-density rechargeable lithium batteries.

[0048] negative electrode 20

[0049] 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).

[0050] For example, based on a 100 wt% negative electrode active material layer AML2, the negative electrode active material layer AML2 may include about 90 wt% to about 99.5 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.

[0051] The binder can be used to adhere the negative electrode active material particles well or appropriately to each other and also to adhere the negative electrode active material well or appropriately to the negative electrode current collector COL2. The binder may include non-aqueous binders, aqueous binders, dry binders and / or combinations thereof (e.g., any suitable combination).

[0052] Non-aqueous adhesives may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide and / or combinations thereof (e.g., any suitable combination).

[0053] Waterborne adhesives may be selected from 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, polyvinyl alcohol and / or combinations thereof (e.g., any suitable combination).

[0054] When an 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 (e.g., influencing) 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, or Li.

[0055] The drying binder can be a polymeric material capable of being fibrous (e.g., in fibrous form). For example, the drying binder can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide and / or combinations thereof (e.g., any suitable combination).

[0056] Conductive materials can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesired chemical changes in a rechargeable lithium battery) and conducts electrons can be used in a battery. Non-limiting examples thereof may include: carbonaceous materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube); metallic materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or a mixture thereof (e.g., any suitable mixture).

[0057] The negative electrode current collector COL2 may include a copper foil, a nickel foil, a stainless steel foil, a titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or a combination thereof (e.g., any suitable combination).

[0058] Negative electrode active material

[0059] The negative electrode active material in the negative electrode active material layer AML2 may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, and / or a transition metal oxide.

[0060] The material that reversibly intercalates / deintercalates lithium ions may include carbonaceous negative electrode active materials (such as, for example, crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any suitable combination)). The crystalline carbon may be graphite (such as amorphous (e.g., having an irregular shape), flaky, sheet-like, spherical, or fibrous natural graphite or artificial graphite). The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, etc.

[0061] The lithium metal alloy includes an alloy of lithium and a metal selected from the following: Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0062] The material capable of doping / dedoping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and / or a combination thereof (e.g., any suitable combination)), and / or a combination thereof (e.g., any suitable combination). The Sn-based negative electrode active material may include Sn, SnO x (0 < x ≤ 2, for example, SnO2), a Sn-based alloy, and / or a combination thereof (e.g., any suitable combination).

[0063] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles (e.g., primary silicon particles) are concentrated, and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be present between the primary silicon particles; for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed within the amorphous carbon matrix.

[0064] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating on the surface of the core.

[0065] Si-based or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0066] The negative electrode active material may include at least one selected from graphite and Si composites. The Si composite may contain a core comprising Si-like particles and amorphous carbon.

[0067] If (for example, when) the negative electrode active material comprises both Si composite and graphite, the Si composite and graphite may be included in the form of a mixture, and in embodiments, the Si composite and graphite may be included in a weight ratio of about 1:99 to about 50:50. For example, the Si composite and graphite may be included in a weight ratio of about 3:97 to about 20:80 or about 5:95 to about 20:80.

[0068] Diaphragm 30

[0069] Depending on the type of rechargeable lithium battery, the separator 30 may be present between the positive electrode 10 and the negative electrode 20. The separator 30 may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer membrane of two or more layers thereof (such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polypropylene triple-layer separator, a polypropylene / polypropylene / polypropylene triple-layer separator, etc.).

[0070] The diaphragm 30 may include a porous substrate and a coating on one or both surfaces of the porous substrate (e.g., opposite surfaces) comprising organic materials, inorganic materials and / or combinations thereof (e.g., any suitable combination).

[0071] The porous substrate may be a polymer membrane formed from any one of the following polymers or copolymers or mixtures thereof: polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or 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).

[0072] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0073] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and / or combinations thereof (e.g., any suitable combination), but this disclosure is not limited thereto.

[0074] Organic and inorganic materials can be mixed in a coating, or coatings containing organic materials and coatings containing inorganic materials can be stacked.

[0075] Electrolyte ELL

[0076] Electrolytes (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0077] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery.

[0078] Non-aqueous organic solvents may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof (e.g., any suitable combination).

[0079] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), etc.

[0080] Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, valonate lactone, caprolactone, propyl propionate (PP), etc.

[0081] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc. 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)), amides (such as dimethylformamide), dioxolane (such as 1,3-dioxolane, 1,4-dioxolane, etc.), sulfolane, etc.

[0082] Non-aqueous organic solvents can be used alone or in combination of two or more.

[0083] Additionally, if (for example, when) a carbonate solvent is used, 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.

[0084] 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 at least one selected from the following: LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are each independent 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).

[0085] The electrolyte for a rechargeable lithium battery according to one or more embodiments of the present disclosure will be described in more detail below.

[0086] An electrolyte for a rechargeable lithium-ion battery according to one or more embodiments of the present disclosure may include a non-aqueous organic solvent, a lithium salt, and additives. The non-aqueous organic solvent may include a first compound represented by Formula 1, which will be described in more detail later. The additives may include a second compound represented by Formula 2, which will be described in more detail later.

[0087] Electrolytes can be prepared by a mixing process in which lithium salts are dissolved in a non-aqueous organic solvent and additives are added. The mixing process for preparing the electrolyte can be suitably or appropriately selected from suitable processes in the field of electrolyte preparation (e.g., processes known to those skilled in the art).

[0088] non-aqueous organic solvents

[0089] The non-aqueous organic solvent may include the first compound represented by Formula 1. The first compound may be a difluoroester solvent.

[0090] [Formula 1]

[0091]

[0092] In Equation 1, R 1 It may be a substituted or unsubstituted C1-C6 alkyl group, or a substituted or unsubstituted C1-C12 aryl group, and R 2 It can be a direct bond or a C1-C6 alkylene bond.

[0093] In one or more embodiments, R 1 It can be a substituted or unsubstituted C1-C6 alkyl group, and R 2 It can be a C1 to C6 alkylene group.

[0094] In one or more embodiments, the first compound may be represented by Formula 1-1.

[0095] [Equation 1-1]

[0096]

[0097] In one or more embodiments, the amount of the first compound may be from about 50 vol% to about 85 vol% based on the total volume (100 vol%) of the non-aqueous organic solvent. In one or more embodiments, the amount of the first compound may be from about 60 vol% to about 85 vol%. In one or more embodiments, the amount of the first compound may be from about 70 vol% to about 80 vol%.

[0098] The first compound enhances battery stability. It provides flame retardancy and contributes to the stable formation of the solid electrolyte interphase (SEI) layer. The first compound includes fluorine, which has high electronegativity, thus exhibiting high oxidation stability, preventing or reducing electrolyte oxidation. For example, under unstable conditions of high temperature and / or high voltage, it effectively inhibits or reduces the oxidative decomposition of the electrolyte (e.g., because the first compound is contained in a non-aqueous organic solvent), thereby preventing or reducing fire. Furthermore, the fluorine included in the first compound can be reduced on the electrode surface (e.g., reacting with the electrode) to form lithium fluoride (LiF). Because lithium fluoride (LiF) is a stable material that is not easily decomposed by the external environment, it enhances the chemical stability of the SEI layer.

[0099] Although the first compound enhances battery stability as described above, it can potentially degrade battery performance if present in excessive amounts. For example, if the amount of the first compound is excessive, the viscosity of the electrolyte can increase, and the SEI layer (e.g., a LiF layer formed by reduction of the first compound on the electrode surface) can become excessively (or considerably) thick. Consequently, lithium ion movement can be hindered, and the internal resistance of the battery can increase. In the electrolyte according to embodiments of this disclosure, this problem can be minimized or reduced by controlling the amount of the first compound within the aforementioned optimal or appropriate range. Furthermore, by using the second compound, which will be described in more detail later, in conjunction with the first compound, battery performance can be further improved, and the poor performance caused by the first compound can be effectively addressed.

[0100] In one or more embodiments, the non-aqueous organic solvent may further comprise a carbonate solvent. Based on the total volume (100 vol%) of the non-aqueous organic solvent, the amount of the carbonate solvent may be from about 15 vol% to about 50 vol%. In one or more embodiments, this amount may be from about 15 vol% to about 40 vol%. In one or more embodiments, this amount may be from about 20 vol% to about 30 vol%.

[0101] The volume ratio of the first compound to the carbonate solvent may be from about 50:50 to about 75:25. In one or more embodiments, the volume ratio of the first compound to the carbonate solvent may be from about 60:40 to about 75:25.

[0102] Carbonate solvents can improve the fluidity of the electrolyte (e.g., reduce viscosity), so when used in combination with a first compound, they can compensate for the disadvantages of the first compound (e.g., to provide an electrolyte with an appropriate viscosity). However, carbonate solvents are readily oxidized and decomposed at high voltages of about 4.45V or higher to form a resistive layer on the electrode surface. Therefore, if the amount of carbonate solvent is excessive, problems such as increased battery resistance, gas generation, and electrolyte consumption can occur. For example, the positive electrode charging potential can increase due to substantially continuous charge and discharge cycles, further exacerbating the aforementioned problems. If the amount of carbonate solvent is kept within the aforementioned range, the problems of carbonate solvents can be minimized or reduced, and the disadvantages of the first compound can be effectively compensated for.

[0103] In one or more embodiments, the non-aqueous organic solvent may include ethylene carbonate (EC), propylene carbonate (PC), and the first compound. However, the above embodiments are merely one or more embodiments using one or more suitable carbonate solvents, and this disclosure is not limited thereto.

[0104] lithium salts

[0105] In one or more embodiments, the lithium salt may be selected from one, two or more of the following: LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, lithium bis(fluorosulfonyl)imide (Li(FSO2)2N, LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are each independent 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).

[0106] In one or more embodiments, the lithium salt may include LiPF6.

[0107] In one or more embodiments, the lithium salt may have a concentration of about 0.1 M to about 2.0 M. For example, the concentration of the lithium salt may be about 0.5 M or more, or about 0.8 M or more. The concentration of the lithium salt may be about 2.0 M or less, about 1.7 M or less, or about 1.5 M or less. When the concentration falls within the above ranges, the conductivity and viscosity of the electrolyte can be suitably or appropriately maintained.

[0108] additive

[0109] The additives according to embodiments of this disclosure may include a second compound represented by Formula 2.

[0110] [Equation 2]

[0111]

[0112] In Equation 2, n can be an integer from 1 to 8.

[0113] In one or more embodiments, n in Equation 2 can be an integer from 4 to 7.

[0114] In one or more embodiments, the second compound may be one of the compounds represented by Formula 2-1 to Formula 2-3.

[0115] [Equation 2-1]

[0116]

[0117] [Equation 2-2]

[0118]

[0119] [Equation 2-3]

[0120]

[0121] The amount of the second compound may be from about 0.1 wt% to about 10 wt% based on the total weight of the electrolyte containing the exclusion additives for the rechargeable lithium battery. In one or more embodiments, the amount may be from about 0.1 wt% to about 5 wt%. In one or more embodiments, the amount may be from about 0.1 wt% to about 1.5 wt%. The amount of the second compound refers to the relative weight of the second compound based on 100 wt% of the total electrolyte (lithium salt + non-aqueous organic solvent) containing the exclusion additives.

[0122] The second compound can be a dimer in which two triazole groups are linked by an alkylene linking group. The triazole group can (e.g., by reacting with the first compound) remove HF caused by degradation of the positive electrode and stabilize the interaction between the electrolyte and the electrode. Accordingly, battery performance can be improved. For example, the two triazole groups are positioned adjacent to each other to act synergistically. While one triazole group binds to the target (e.g., HF), the other triazole group can exert additional interaction, thereby achieving more efficient HF removal and stabilization of the interaction.

[0123] As the alkylene linking group, a C1-C8 alkylene linking group without functional groups (e.g., without reactive groups) can be used. In one or more embodiments, the alkylene linking group may have about 4 to about 7 carbon atoms. If, for example, the number of carbon atoms in the alkylene linking group is too small, the two triazole groups may be too close to each other, resulting in steric hindrance. Therefore, only one triazole group can participate in the reaction to function as a monomer. If, for example, the number of carbon atoms in the alkylene linking group is too large, the molecular structure may become too unstable, and the desired or proper interaction may not occur.

[0124] According to embodiments of this disclosure, the second compound can be used in combination with the first compound to achieve a synergistic effect. While the first compound enhances battery stability as described above, it may (potentially) have the problem of degrading battery performance (e.g., performance degradation due to the formation of a thick SEI layer). The second compound can compensate for the performance degradation caused by the first compound to improve battery performance. If another type (class) of ester solvent is used instead of the first compound, the desired or appropriate improvement in stability and performance may not be achieved.

[0125] Rechargeable lithium batteries

[0126] Based on their shape, rechargeable lithium batteries can be classified into cylindrical batteries, prismatic batteries, pouch-type batteries, coin-type batteries, etc. Figures 2-5 Schematic diagrams illustrating rechargeable lithium batteries according to one or more embodiments, Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 A pouch-type (or similar) battery is shown. (Reference) Figures 2-5 The rechargeable lithium battery 100 may include a separator 30 disposed between a positive electrode 10 and a negative electrode 20, and a housing 50 therein housing an electrode assembly 40. The positive electrode 10, negative electrode 20, and separator 30 may be impregnated with an electrolyte. Figure 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of a sealed housing 50. Furthermore, in 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, in... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include electrode terminals 70, which may serve as electrical paths for guiding current formed in the electrode assembly 40 to the outside, such as positive electrode terminal 71 and negative electrode terminal 72.

[0127] The rechargeable lithium battery according to one or more embodiments of the present disclosure can be applied to automobiles, mobile phones, and / or one or more appropriate types (categories) of electronic devices, and the present disclosure is not limited thereto.

[0128] The rechargeable lithium battery according to one or more embodiments of the present disclosure may include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and the electrolyte for the rechargeable lithium battery described above.

[0129] In one or more embodiments, the positive electrode active material may include a lithium composite oxide represented by Formula 3:

[0130] [Formula 3]

[0131] Li x M 1 y M 2 z M 3 1-y-z O 2-a X a

[0132] It may satisfy 0.5 ≤ x ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 < y + z ≤ 1.

[0133] M 1 、M 2 and M 3 may each independently include (for example, may be) one or more elements selected from Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Y, Zr, and La.

[0134] X may include (for example, may be) one or more elements selected from F, S, P, and Cl.

[0135] In one or more embodiments, the positive electrode active material may include a lithium cobalt-based oxide having a layered crystal structure.

[0136] In one or more embodiments, the negative electrode active material may include a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, and / or a combination thereof (for example, any suitable combination).

[0137] In one or more embodiments, the negative electrode active material may include graphite.

[0138] Thanks to the improved stability of non-aqueous organic solvents in the electrolyte and the enhanced performance of additives, rechargeable lithium batteries maintain excellent or adequate performance even at high voltages without ignition. High voltages can be approximately 4.0V or higher, 4.4V or higher, or 4.5V or higher.

[0139] Examples and Comparative Examples

[0140] The following describes embodiments and comparative examples of this disclosure. However, the following embodiments are merely implementations of this disclosure, and this disclosure is not limited to the following embodiments.

[0141] Example 1

[0142] (1) Preparation of electrolyte

[0143] LiPF6 was dissolved at approximately 1.3 M in a non-aqueous organic solvent in which the first compound and a carbonate solvent were mixed at the volume ratios shown in Table 1. The second compound was then added and mixed to prepare the electrolyte. Electrolytes according to the examples and comparative examples were prepared based on the compositions listed in Table 1. As previously stated, the amount of the second compound refers to the relative weight of the second compound based on 100 wt% of the total electrolyte (lithium salt + non-aqueous organic solvent) excluding additives.

[0144] The compound represented by Formula 1-1 is used as the first compound, and the compound represented by Formula 2-2 is used as the second compound.

[0145] [Equation 1-1]

[0146]

[0147] [Equation 2-2]

[0148]

[0149] [Table 1]

[0150]

[0151]

[0152] (2) Preparation of rechargeable lithium batteries

[0153] Approximately 97 wt% of LiCoO2 (LCO) as the positive electrode active material, approximately 0.5 wt% of artificial graphite powder as the conductive material, approximately 0.8 wt% of carbon black as the conductive material, approximately 0.2 wt% of acrylonitrile-butadiene rubber as the binder, and approximately 1.5 wt% of polyvinylidene fluoride (PVdF) as the binder were mixed and added to N-methyl-2-pyrrolidone (NMP). The mixture was then stirred using a mechanical stirrer for approximately 30 minutes to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated onto an aluminum current collector with a thickness of approximately 20 μm using a doctor blade. The coated positive electrode active material slurry was dried in a hot air dryer at approximately 100°C for approximately 0.5 hours, and then dried again under vacuum at approximately 120°C for approximately 4 hours. Finally, the mixture was rolled to prepare the positive electrode.

[0154] A negative electrode active material, comprising approximately 98 wt% of a graphite and Si composite mixed in a weight ratio of approximately 95.8:4.2, approximately 1 wt% of styrene-butadiene rubber (SBR), and approximately 1 wt% of carboxymethyl cellulose (CMC), was mixed and then added to distilled water. The mixture was stirred using a mechanical stirrer for approximately 60 minutes to prepare a negative electrode active material slurry. The negative electrode active material slurry was coated to a thickness of approximately 60 μm onto a copper current collector having a thickness of approximately 10 μm using a doctor blade. The coated negative electrode active material slurry was dried in a hot air dryer at approximately 100°C for approximately 0.5 hours, then dried again under vacuum at approximately 120°C for approximately 4 hours, and finally rolled to prepare the negative electrode.

[0155] The Si composite has a core consisting of artificial graphite and Si particles, and coal tar pitch coated on the surface of the core.

[0156] A positive electrode, a negative electrode, and a polyethylene separator with a thickness of approximately 16 μm were assembled to prepare an electrode assembly, and an electrolyte was injected to prepare a rechargeable lithium battery.

[0157] Evaluation Example 1: Evaluation of Flame Retardant Properties

[0158] For each of the rechargeable lithium batteries prepared according to the examples and comparative examples, the flash point was measured using a Grabner Instruments Miniflash FP Vision. The sample was placed in a sealed container (closed cup), and the sample inside the container was slowly heated. The gas inside the container was ignited at regular intervals by an ignition source (such as an electric spark) built into the instrument, and the temperature at which the gas ignited instantaneously was recorded. The results are listed in Table 2.

[0159] Evaluation Example 2: Evaluation of High-Temperature Lifetime Characteristics

[0160] The rechargeable lithium batteries prepared according to each of the examples and comparative examples were subjected to 400 charge-discharge cycles at approximately 45°C, charged at approximately 2.0C (CC / CV, 4.53V, 0.05C cutoff) and discharged at approximately 1.0C (CC, 3.0V cutoff), and then the battery characteristics were measured. The capacity retention rate was calculated according to Equation 1. The results are listed in Table 2.

[0161] [Equation 1]

[0162] Capacity retention (%) = (Discharge capacity after 400 cycles / Initial discharge capacity) x 100

[0163] Evaluation Example 3: Evaluation of High-Temperature Storage Characteristics

[0164] The rechargeable lithium batteries prepared according to the examples and comparative examples were charged at 45°C, 0.5C, 4.53V, and a 0.05C cutoff condition. The battery thickness was measured immediately after charging, i.e., the initial thickness. The batteries were then left to stand at approximately 60°C for 28 days, and the thickness of the batteries after standing was measured, i.e., the thickness after 28 days. Each thickness was measured using a Mitutoyo compression (type) thickness gauge, in which the pouch battery cell (the pouch battery cell used for measurement) was placed between pressure plates and then compressed with a weight of approximately 300g to measure the thickness. The thickness increase rate was calculated according to Equation 2. The results are listed in Table 2.

[0165] [Equation 2]

[0166] Thickness increase rate (%) = (Thickness after 28 days / Initial thickness) x 100

[0167] [Table 2]

[0168]

[0169] Referring to Tables 1 and 2, each of the embodiments according to this disclosure exhibits superior or suitable flame retardant properties, high-temperature life characteristics, and storage characteristics compared to each of the comparative examples. For example, it can be seen that the electrolyte and battery according to the embodiments of this disclosure simultaneously (e.g., synchronously or together) possess both high stability and superior or suitable battery performance.

[0170] Electrolytes for rechargeable lithium-ion batteries according to one or more embodiments of this disclosure can improve battery life characteristics and stability. Rechargeable lithium-ion batteries according to one or more embodiments of this disclosure can have excellent or adequate life characteristics and stability. The innovative electrolyte composition not only ensures high energy density and capacity but also provides enhanced safety features, making the batteries ideally suited for use in a variety of electronic devices and / or electric vehicles.

[0171] For example, according to embodiments of this disclosure, the electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent; a lithium salt; and an additive, wherein the non-aqueous organic solvent includes a first compound represented by Formula 1, and the additive includes a second compound represented by Formula 2. By including both the first and second compounds, a synergistic effect is achieved, and the battery simultaneously exhibits excellent stability and lifespan characteristics even at high temperatures. For example, by including the first compound represented by Formula 1, which has two fluorine atoms, battery stability is improved, and a stable SEI layer can be formed on the electrode. Furthermore, by including the additive represented by Formula 2, which has two triazole groups (e.g., by reacting with the first compound), HF caused by the degradation of the positive electrode can be removed, and the interaction between the electrolyte and the electrode can be stabilized. Therefore, the battery's flame retardancy, storage stability, and performance are all improved.

[0172] The electrolyte according to embodiments of this disclosure may further include carbonate solvents in a non-aqueous organic solvent, which may further improve the viscosity of the electrolyte to an appropriate range and further improve battery performance.

[0173] When describing embodiments of the inventive concept, the word "may" refers to "one or more embodiments of the inventive concept".

[0174] As used herein, the term "about" and similar terms are used as approximations and not as terms of degree, and are intended to describe the inherent bias in a measured or calculated value that would be recognized by one of ordinary skill in the art. As used herein, the term "about" includes the stated value and means within an acceptable range of deviation for a particular value, determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0175] Furthermore, any numerical range set forth herein is intended to include all subranges of the same numerical precision falling within the set forth range. For example, the range “1.0 to 10.0” is intended to include (and inclusive) the stated minimum value of 1.0 and the stated maximum value of 10.0, that is, all subranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits falling within it, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling within it. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly set forth any subranges falling within the range expressly set forth herein.

[0176] When expressions such as “at least one of…” and “any one of…” precede / follow a list of elements, they modify the entire list of elements and not individual elements of the list. When phrases such as “at least one of A, B, and C,” “at least one of the group selected from A, B, and C,” or “at least one of A, B, and C” are used to specify a list of elements A, B, and C, the phrase may refer to any and all appropriate combinations or subsets of A, B, and C (such as A, B, C, A and B, A and C, B and C, or A and B and C). The terms “use,” “using,” and “used” as used herein may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively.

[0177] The description of features or aspects within the scope of each implementation should generally be considered applicable to other similar features or aspects in other implementations.

[0178] The battery formation or manufacturing system, battery management system (BMS) device, and / or any other related device or component according to embodiments of the invention described herein can be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, various components of the device may be formed on an integrated circuit (IC) chip or on a separate IC chip. Furthermore, various components of the device may be implemented on a flexible printed circuit film, a tape-on package (TCP), or a printed circuit board (PCB), or formed on a substrate. Additionally, various components of the device may be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components to perform the various functions described herein. The computer program instructions are stored in memory, which may be implemented using standard memory devices (such as, for example, random access memory (RAM)) in the computing device. The computer program instructions may also be stored in other non-transitory computer-readable media (such as, for example, CD-ROM or flash memory drives). Moreover, those skilled in the art will recognize that, without departing from the scope of this disclosure, the functionality of various computing devices may be combined or integrated into a single computing device, or the functionality of a dedicated computing device may be distributed across one or more other computing devices.

[0179] Although one or more embodiments of this disclosure have been described with reference to the accompanying drawings, it should be understood that this disclosure is not limited to these embodiments, and one or more suitable changes and modifications may be made within the spirit and scope of the claims and their equivalents, the detailed description of the invention and the accompanying drawings, and these also fall within the scope of this disclosure.

Claims

1. An electrolyte comprising: a non-aqueous organic solvent; a lithium salt; and an additive, wherein the non-aqueous organic solvent comprises a first compound represented by Formula 1, and the additive comprises a second compound represented by Formula 2: Formula 1 wherein, in Formula 1, R 1 is substituted or unsubstituted C1-C6 alkyl, or substituted or unsubstituted C1-C12 aryl, and R 2 is a direct bond or C1-C6alkylene, and Formula 2 wherein, in Formula 2, n is an integer of 1 to 8, and wherein the electrolyte is an electrolyte for a rechargeable lithium battery, the term "substituted" means that at least one hydrogen of a substituent or a compound is replaced with deuterium, a halogen group, a hydroxyl group, an amino group, a C1-C30 amine group, a nitro group, a C1-C40 silyl group, a C1-C30 alkyl group, a C1-C10 alkylsilyl group, a C6-C30 arylsilyl group, a C3-C30 cycloalkyl group, a C3-C30 heterocycloalkyl group, a C6-C30 aryl group, a C2-C30 heteroaryl group, a C1-C20 alkoxy group, a C1-C10 fluoroalkyl group, a cyano group, and / or a combination thereof. 2.The electrolyte of claim 1, wherein R 1 is substituted or unsubstituted C1-C6 alkyl, and R 2 R is C1-C6alkylene. 3.The electrolyte of claim 1, wherein the first compound is represented by Formula 1-1: Formula 1-1 4.The electrolyte of claim 1, wherein the content of the first compound is 50 vol% to 85 vol% based on the total volume of the non-aqueous organic solvent. 5.The electrolyte of claim 1, wherein the non-aqueous organic solvent further comprises a carbonate-based solvent, and the carbonate-based solvent is 15 vol% to 50 vol% based on the total volume of the non-aqueous organic solvent. 6.The electrolyte of claim 1, wherein the non-aqueous organic solvent further comprises a carbonate-based solvent, and the volume ratio of the first compound and the carbonate-based solvent is 50:50 to 75:

25. 7.The electrolyte of claim 1, wherein the non-aqueous organic solvent comprises ethylene carbonate, propylene carbonate, and the first compound.

8. The electrolyte of claim 1, wherein, In Formula 2, n is an integer of 4 to 7. 9.The electrolyte of claim 1, wherein the second compound is one of compounds represented by Formulas 2-1 to 2-3: Formula 2-1 Formula 2-2 Formula 2-3 10.The electrolyte of claim 1, wherein the second compound is 0.1 wt% to 10 wt% based on the total weight of the non-aqueous organic solvent and the lithium salt. 11.The electrolyte of claim 1, wherein the second compound is 0.1 wt% to 5 wt% based on the total weight of the non-aqueous organic solvent and the lithium salt.

12. The electrolyte of claim 1, wherein the lithium salt is at least one selected from the group consisting of LiPF6; LiBF4; LiSbF6; LiAsF6; LiClO4; LiAlO2; LiAlCl4; LiPO2F2; LiCl; LiI; LiN(SO3C2F5)2; lithium bis(fluorosulfonyl)imide; LiC4F9SO3; LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), wherein x and y are each independently an integer of 1 to 20; lithium trifluoromethanesulfonate; lithium tetrafluoroethanesulfonate; lithium difluoro(oxalato)borate; lithium difluorobis(oxalato)phosphate; and lithium bis(oxalato)borate. 13.The electrolyte of claim 1, wherein the lithium salt comprises LiPF 6. 14.The electrolyte of claim 1, wherein the concentration of the lithium salt is 0.1 M to 2.0 M. 15.A rechargeable lithium battery comprising: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; and the electrolyte of any one of claims 1 to 14. 16.The rechargeable lithium battery of claim 15, wherein the positive electrode active material comprises a lithium complex oxide represented by Formula 3: Formula 3 Li x M 1 y M 2 z M 3 1-y-z O 2-a X a , and wherein, 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 elements selected from Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Y, Zr, and La, and X comprises one or more elements selected from F, S, P, and CI.

17. The rechargeable lithium battery of claim 15, wherein the positive electrode active material comprises a lithium cobalt-based oxide having a layered crystal structure.

18. The rechargeable lithium battery of claim 15, wherein the negative electrode active material comprises a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, or a combination thereof.

19. The rechargeable lithium battery of claim 15, wherein the negative electrode active material comprises graphite.

20. The rechargeable lithium battery of claim 15, wherein the rechargeable lithium battery is configured to operate even at a voltage of 4.5 V or higher.

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