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. The electrolyte includes: a non-aqueous organic solvent; a lithium salt; lithium bis (oxalate) borate (LiBOB); a first compound represented by Chemical Formula 1; and a second compound 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 and the benefit of Korean Patent Application No. 10-2024-0050660 filed in the Korean Intellectual Property Office on April 16, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] One or more embodiments of the present disclosure relate to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte. Background Art

[0004] Recently, with the rapid promotion and popularization of batteries for electronic devices (such as mobile phones, laptop computers and / or electric vehicles), the demand for such batteries (e.g., rechargeable batteries) with relatively high energy density and high capacity is rapidly increasing. That is, with the rapid promotion and popularization of batteries in electronic devices (such as mobile phones, laptop computers and / or electric vehicles), the demand for rechargeable batteries with high energy density and capacity is rapidly increasing. Therefore, intensive research has been conducted to improve the performance of such rechargeable batteries (e.g., rechargeable lithium batteries).

[0005] Rechargeable lithium batteries include a positive electrode, a negative electrode, and an electrolyte. The positive electrode and the negative electrode each include an active material capable of intercalating and deintercalating lithium ions, and when the lithium ions are intercalated and deintercalated, electric energy is generated due to oxidation and reduction reactions. Summary of the Invention

[0006] One or more aspects of embodiments of the present disclosure are directed to an electrolyte for a rechargeable lithium battery having excellent or appropriate high-temperature characteristics and superior stability.

[0007] One or more aspects of embodiments of the present disclosure relate to a rechargeable lithium battery including an electrolyte.

[0008] Additional 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 the presented embodiments of the disclosure.

[0009] According to one or more embodiments of the present disclosure, an electrolyte for a rechargeable lithium battery may include: a non-aqueous organic solvent; a lithium salt; lithium bis(oxalato)borate (LiBOB); a first compound represented by Chemical Formula 1; and a second compound represented by Chemical Formula 2.

[0010] Chemical formula 1

[0011]

[0012] In Chemical Formula 1,

[0013] R 1a ~R 8a may each independently be hydrogen, halo, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C3-C20 cycloalkynyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C2-C30 heterocyclyl, and

[0014] k can be 0 or 1.

[0015] Chemical Formula 2

[0016]

[0017] In Chemical Formula 2,

[0018] A 1 may be O or C(R 1b )(R 2b ),

[0019] A 2 may be O or C(R 3b )(R 4b ),

[0020] B 1 may be C(R 5b )(R 6b ) or carbonyl,

[0021] B 2 may be C(R 7b )(R 8b ) or carbonyl,

[0022] B 3 may be C(R 9b )(R 10b ) or carbonyl,

[0023] B 4 may be C(R 11b )(R 12b ) or carbonyl,

[0024] R 1b ~R 12beach independently hydrogen, halogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C3-C20 cycloalkynyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C2-C30 heterocyclyl,

[0025] n1, n2, m1, and m2 can each independently be an integer of 0 or 1, and

[0026] n1 + m1 ≥ 1 and n2 + m2 ≥ 1.

[0027] According to one or more embodiments of the present disclosure, a rechargeable lithium battery can include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte (e.g., the aforementioned electrolyte). BRIEF DESCRIPTION OF DRAWINGS

[0028] The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 FIG. 1 is a simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0030] Figures 2 to 5 FIGS. 2 and 3 are simplified diagrams each illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0031] For a full understanding of the configuration and aspects of the present disclosure, one or more embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it is to be noted that the present disclosure is not limited to the following example embodiments and can be implemented in one or more appropriate forms. Rather, the example embodiments are provided only to explain the present disclosure and to fully enable the scope of the present disclosure to those skilled in the art.

[0032] In the present disclosure, it will be understood that, if (for example, when) an element is referred to as being "on" another element, it can be directly on the other element, or intervening elements can be present therebetween. In contrast, if (for example, when) an element is referred to as being "directly on" another element, there are no intervening elements present. In the drawings, the thickness of some components can be exaggerated for effective explanation of the technical content. Throughout the present disclosure, the same reference numerals refer to the same elements, and repeated description thereof can not be provided for the sake of brevity.

[0033] The singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the use of "may" when describing embodiments of the present disclosure indicates that one or more embodiments of the present disclosure. Additionally, the phrases "A or B" or "A and / or B" or "A / B" can indicate A but not B, B but not A, and A and B, unless otherwise indicated expressly. The use of the terms "including," "comprising," and / or "having" in the present disclosure does not exclude one or more other components or additives.

[0034] The term "combination thereof as used herein can refer to a mixture, a stack, a composite, a copolymer, an alloy, a blend, or a reaction product of ingredients.

[0035] Unless otherwise specifically defined in the present disclosure, the particle size can be an average particle size. In addition, the particle size indicates an average particle size (D 50 ) at which the cumulative volume is 50% by volume in a particle size distribution. The average particle size (D 50 ) can be measured by methods generally known to those skilled in the art (e.g., by a particle size analyzer, for example, HORIBA, LA-950 laser particle size analyzer, a transmission electron microscope (TEM), or a scanning electron microscope (SEM)). In one or more embodiments, data analysis is performed using a dynamic light scattering measuring device, counting the number of particles for each particle size range, and then obtaining an average particle size (D 50 ) value from the data by calculation. In some embodiments, a laser scattering method can be used to measure the average particle size (D 50 ). In the laser scattering method, the target particles are distributed in a dispersion solvent, introduced into a laser scattering particle measuring device (e.g., MT3000, which is commercially available from Microtrac, Inc.), irradiated with 28 kHz ultrasonic waves at a power of 60 W, and then the average particle size (D 50 ) is calculated in the measuring device at a standard particle size distribution of 50%. The D 50 indicates an average diameter (or size) of particles at which the cumulative volume corresponds to 50% by volume in a particle size distribution (e.g., a cumulative distribution), and indicates a value corresponding to a particle size of 50% from the smallest particle when the total number of particles is 100% in a distribution curve accumulated in order of the smallest particle size to the largest particle size. In the present disclosure, when the particles are spherical, "diameter" indicates the average particle size, and when the particles are non-spherical, "diameter" indicates the length of the major axis. The D 50 The particles can be measured by a particle size analyzer using a laser diffraction method.

[0036] In the present disclosure, unless otherwise defined separately, the term "substituted" can refer to at least one hydrogen of a substituent or a compound being replaced with deuterium, halo, hydroxyl, amino, C1-C30 amine group, nitro, C1-C40 silyl group, C1-C30 alkyl group, C1-C10 alkylsilyl group, C6-C30 arylsilyl group, C3-C30 cycloalkyl group, C3-C30 heterocycloalkyl group, C6-C30 aryl group, C2-C30 heteroaryl group, C1-C20 alkoxy group, C1-C10 fluoroalkyl group, cyano, and / or a combination (e.g., any suitable) thereof.

[0037] For example, in one or more embodiments, the term "substituted" can refer to at least one hydrogen of a substituent or a compound being replaced with deuterium, halo, C1-C30 alkyl group, C1-C10 alkylsilyl group, C6-C30 arylsilyl group, C3-C30 cycloalkyl group, C3-C30 heterocycloalkyl group, C6-C30 aryl group, C2-C30 heteroaryl group, C1-C10 fluoroalkyl group, or cyano. In one or more embodiments, the term "substituted" can refer to at least one hydrogen of a substituent or a compound being replaced with deuterium, halo, C1-C20 alkyl group, C6-C30 aryl group, C1-C10 fluoroalkyl group, or cyano. In one or more embodiments, the term "substituted" can refer to at least one hydrogen of a substituent or a compound being replaced with deuterium, halo, C1-C5 alkyl group, C6-C18 aryl group, C1-C5 fluoroalkyl group, or cyano. In one or more embodiments, the term "substituted" can refer to at least one hydrogen of a substituent or a compound being replaced with deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl. The alkyl group can include linear alkyl group and / or chained alkyl group. The cycloalkyl group can include cyclic alkyl group.

[0038] Figure 1 A simplified conceptual diagram of a rechargeable lithium battery according to one or more embodiments of the present disclosure is shown. Referring to FIG. 1, Figure 1 The rechargeable lithium battery can include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0039] The positive electrode 10 and the negative electrode 20 can be spaced and / or separated (e.g., spaced apart or separated) from each other across the separator 30. The separator 30 can be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 can be in contact with the electrolyte ELL. For example, the positive electrode 10, the negative electrode 20, and the separator 30 can be immersed in and / or impregnated with the electrolyte ELL.

[0040] The electrolyte ELL can be a medium through which lithium ions migrate and are delivered between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, the lithium ions can move toward (e.g., selected from) one of the positive electrode 10 and the negative electrode 20 through the separator 30.

[0041] positive electrode 10

[0042] The positive electrode 10 for a rechargeable lithium battery can 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 can include a positive electrode active material (e.g., in the form of particles), and can further include a binder and / or a conductive material (e.g., an electronic conductor).

[0043] For example, in some embodiments, the positive electrode 10 can further include a component serving as a sacrificial positive electrode.

[0044] The amount of the positive electrode active material can be in the range of about 90 wt% to about 99 wt% with respect to (i.e., based on) the total weight of the positive electrode active material layer AML1 of 100 wt%. The amount of each of the binder and the conductive material can be about 0.5 wt% to about 5 wt% with respect to (i.e., based on) the total weight of the positive electrode active material layer AML1 of 100 wt%.

[0045] The binder can serve to improve adhesion of the positive electrode active material particles to each other, and also to improve adhesion of the positive electrode active material to the positive electrode current collector COL1. The binder can include, for example, one or more selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, and nylon, although embodiments of the present disclosure are not limited thereto.

[0046] The conductive material (e.g., an electrically conductive material or an electronically conductive material) can serve to provide electrical conductivity to the electrode, and any suitable conductive material that does not cause chemical changes in the battery can be used as the conductive material constituting the battery. The conductive material can include, for example, a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube; a metal powder or a metal fiber containing (e.g., selected from) one or more of copper, nickel, aluminum, and silver; a conductive polymer such as a polyphenylene derivative; and / or a mixture (e.g., any suitable) thereof.

[0047] In one or more embodiments, an aluminum (Al) foil can be used as the positive electrode current collector COL1, although embodiments of the present disclosure are not limited thereto.

[0048] positive electrode active material

[0049] The positive electrode active material in the positive electrode active material layer AML1 can include a compound that can reversibly intercalate and deintercalate lithium (e.g., a lithiated intercalation compound). For example, in one or more embodiments, the positive electrode active material can include at least one kind of composite oxide including lithium and a metal selected from cobalt, manganese, nickel, and / or a combination thereof (e.g., any suitable combination).

[0050] The composite oxide can include a lithium transition metal composite oxide, for example, a lithium nickel-based composite oxide, a lithium cobalt-based composite oxide, a lithium manganese-based composite oxide, a lithium iron phosphate-based composite compound, a cobalt-free nickel manganese-based composite oxide, and / or a combination thereof (e.g., any suitable combination).

[0051] For example, in one or more embodiments, the positive electrode active material can include a compound represented by one selected from the following chemical formulas: a A 1-b X b O 2-c D c (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0≤α<2); Li a Mn 2-b X b O 4-c D c( (wherein 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0≤α<2); Li a Ni 1-b-c Co b X c O 2-α D α (wherein 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 (wherein 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(wherein 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(wherein 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a CoG bO2(wherein 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1-b G b O2(wherein 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn2G b O4(wherein 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn 1- g G g PO4(wherein 0.90≤a≤1.8 and 0≤g≤0.5); Li (3-f) Fe2(PO4)3(wherein 0≤f≤2); Li a FePO4(wherein 0.90≤a≤1.8).

[0052] In the foregoing chemical formulas, A can be nickel (Ni), cobalt (Co), manganese (Mn), and / or a combination thereof (e.g., any suitable combination), X can be Al, Ni, Co, Mn, chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), a rare earth element, and / or a combination thereof (e.g., any suitable combination), D can be oxygen (O), fluorine (F), sulfur (S), phosphorus (P), and / or a combination thereof (e.g., any suitable combination), G can be Al, Cr, Mn, Fe, Mg, lanthanum (La), cerium (Ce), Sr, V, and / or a combination thereof (e.g., any suitable combination), and L 1 may be Mn, Al, and / or a combination thereof (e.g., any suitable combination).

[0053] For example, in one or more embodiments, the positive electrode active material can be a high-nickel type positive electrode active material having a nickel amount equal to or greater than about 80 mol%, equal to or greater than about 85 mol%, equal to or greater than about 90 mol%, equal to or greater than about 91 mol%, or equal to or greater than about 94 mol% and equal to or less than about 99 mol% relative to 100 mol% of total metals other than lithium in the lithium transition metal composite oxide. The high-nickel type positive electrode active material can achieve a high capacity, and thus can be applied to a high-capacity and high-density rechargeable lithium battery.

[0054] Negative electrode 20

[0055] The negative electrode 20 for the rechargeable lithium battery can 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 can include a negative electrode active material (e.g., in the form of particles), and can further include a binder and / or a conductive material (e.g., an electronic conductor).

[0056] For example, in one or more embodiments, the negative electrode active material layer AML2 can include about 90 wt% to about 99 wt% of a negative electrode active material, about 0.5 wt% to about 5 wt% of a binder, and about 0 wt% to about 5 wt% of a conductive material, based on the total weight of the negative electrode active material layer AML2 of 100 wt%.

[0057] The binder can be used to improve adhesion of the negative electrode active material particles to each other, and also to improve adhesion of the negative electrode active material to the negative electrode current collector COL2. The binder can include a non-aqueous (e.g., water-insoluble) binder, an aqueous (e.g., water-soluble) binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0058] The non-aqueous binder can include polyvinyl chloride, carboxylated polyvinyl chloride, polyfluoroethylene, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, and / or a combination thereof (e.g., any suitable combination).

[0059] The aqueous binder can include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, 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 a combination thereof (e.g., any suitable combination).

[0060] When the aqueous binder is used as the binder in the negative electrode active material layer AML2, a cellulose-based compound capable of providing viscosity can be further included as a viscosity enhancer. The cellulose-based compound can include one or more selected from carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal can include Na, K, or Li.

[0061] The dry binder can include a fibrillated polymeric material, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or a combination thereof (e.g., any suitable combination).

[0062] A conductive material (e.g., an electrically conductive material or an electronically conductive material) can be used to provide electrical conductivity to the electrode, and any suitable electrically conductive material that does not cause chemical changes to the battery can be used as the electrically conductive material that constitutes the battery. For example, in one or more embodiments, the electrically conductive material can include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube); metal powders or metal fibers including one or more selected from copper, nickel, aluminum, and silver; electrically conductive polymers (such as polyphenylene derivatives); and / or mixtures (e.g., any suitable) thereof.

[0063] The negative electrode current collector COL2 can include a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with an electrically conductive metal, and / or a combination (e.g., any suitable) thereof.

[0064] The negative electrode active material

[0065] The negative electrode active material in the negative electrode active material layer AML2 can include a material that can reversibly intercalate and deintercalate lithium ions, lithium metal, a lithium metal alloy, a material that can be doped and undoped with lithium, or a transition metal oxide.

[0066] The material that can reversibly intercalate and deintercalate lithium ions can include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, and / or a combination (e.g., any suitable) thereof. For example, the crystalline carbon can include graphite, such as amorphous (e.g., irregularly shaped), flaky, flake-like, spherical, or fibrous natural graphite and / or artificial graphite, and the amorphous carbon can include soft carbon, hard carbon, mesophase pitch carbon, coal pitch, and / or calcined coke.

[0067] The lithium metal alloy can include an alloy of lithium and a metal selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), germanium (Ge), aluminum (Al), and tin (Sn).

[0068] The material that can be doped and undoped with lithium can 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 (wherein 0 < x ≤ 2), a Si-Q alloy (wherein Q is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (other than Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and / or a combination (e.g., any suitable) thereof), and / or a combination (e.g., any suitable) thereof. The Sn-based negative electrode active material can include Sn, SnO k(0 < k < 2) (e.g., SnO2), Sn-based alloys, or combinations thereof (e.g., any appropriate combination).

[0069] The silicon-carbon composite can be a composite of silicon and amorphous carbon (e.g., in the form of particles). According to one or more embodiments, the silicon-carbon composite can have a structure in which amorphous carbon coats the surface of each silicon particle. For example, in one or more embodiments, the silicon-carbon composite can include secondary particles (nuclei) in which primary silicon particles are aggregated, and a coating layer (shell) of amorphous carbon on (e.g., at) the surface of the secondary particles. Amorphous carbon can also be located 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.

[0070] In one or more embodiments, the silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core including crystalline carbon and silicon particles, and can also include a coating layer of amorphous carbon on (e.g., at) the surface of the core.

[0071] In one or more embodiments, Si-based negative electrode active materials and / or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0072] Separator 30

[0073] The separator 30 can be present between the positive electrode 10 and the negative electrode 20, based on the type or kind of rechargeable lithium battery. The separator 30 can include one or more selected from polyethylene, polypropylene, and polyvinylidene fluoride, or can have a multi-layer separator thereof, such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene triple-layer separator, or a polypropylene / polyethylene / polypropylene triple-layer separator.

[0074] The separator 30 can include a porous substrate and a coating layer on the surface (e.g., one surface or two opposite surfaces) of the porous substrate, and the coating layer can include an organic material, an inorganic material, and / or combinations thereof (e.g., any appropriate combination).

[0075] The porous substrate can be a polymeric layer including one selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyarylether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyether sulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfides, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon), or can be a copolymer or a mixture including two or more thereof.

[0076] The organic material can include polyvinylidene fluoride-based copolymers and / or (meth)acrylic copolymers.

[0077] The inorganic material can 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 a combination (e.g., any suitable combination) thereof, although embodiments of the present disclosure are not limited thereto.

[0078] In one or more embodiments, the organic material and the inorganic material can be present in a mixed form in one coating layer, or can be present as a stack of a coating layer including the organic material and a coating layer including the inorganic material.

[0079] Electrolyte ELL

[0080] The electrolyte ELL for the rechargeable lithium battery can include a non-aqueous organic solvent and a lithium salt.

[0081] The non-aqueous organic solvent can be used as a medium for transporting ions participating in electrochemical reactions of the battery.

[0082] The non-aqueous organic solvent can include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or a combination (e.g., any suitable combination) thereof.

[0083] The carbonate-based solvent can 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), and / or butylene carbonate (BC).

[0084] The ester-based solvent can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, and / or caprolactone.

[0085] The ether-based solvent can include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and / or tetrahydrofuran. The ketone-based solvent can include cyclohexanone. The alcohol-based solvent can include ethanol and / or isopropyl alcohol. The aprotic solvent can include nitriles such as R-CN (wherein R is a hydrocarbon group having a C2~C20 linear, branched, or cyclic structure, and can include a double bond, an aromatic ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and / or 1.4-dioxolane; and / or sulfolane.

[0086] The non-aqueous organic solvent can be used alone or in the form of a mixture of two or more thereof.

[0087] In addition, if (for example, when) a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate can be used in combination, and the cyclic carbonate and the chain carbonate can be mixed at a volume ratio of about 1:1 to about 1:9.

[0088] The lithium salt can be a material dissolved in a non-aqueous organic solvent to be used as a supply source of lithium ions in a rechargeable lithium battery, and functions in ensuring the basic operation of the rechargeable lithium battery and facilitating the movement of lithium ions between the positive electrode and the negative electrode. The lithium salt can include, for example, 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), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(wherein x and y are integers of 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium bis(oxalato)borate (LiBOB).

[0089] An electrolyte for a rechargeable lithium battery according to one or more embodiments of the disclosure will be described below.

[0090] The electrolyte for a rechargeable lithium battery according to one or more embodiments can include a non-aqueous organic solvent, a lithium salt, lithium bis(oxalato)borate (LiBOB), a first compound represented by Chemical Formula 1, and a second compound represented by Chemical Formula 2.

[0091] Lithium bis(oxalato)borate (LiBOB) can be an amphoteric lithium salt additive that contributes to the replenishment and absorption of lithium at the positive electrode and the negative electrode to facilitate lithium intercalation and deintercalation of the positive electrode active material and the negative electrode active material, thereby improving the charge-discharge characteristics of the rechargeable lithium battery. In addition, compared to the first compound and the second compound that are sulfuric acid salt-based compounds or sulfonic acid salt-based compounds, lithium bis(oxalato)borate (LiBOB) can start to decompose at a relatively low voltage condition to form a film on the positive electrode interface and the negative electrode interface, and thus can effectively prevent or reduce transition metal elution caused by corrosion products of the sulfuric acid salt-based compounds or the sulfonic acid salt-based compounds. In summary, if (for example, when) used in combination with a sulfur-based additive (e.g., a sulfuric acid salt-based compound and / or a sulfonic acid salt-based compound), the electrolyte for a rechargeable lithium battery including lithium bis(oxalato)borate (LiBOB) can improve the lifespan characteristics of the rechargeable lithium battery.

[0092] The content of lithium bis(oxalato)borate (LiBOB) can be about 0.01 wt% to about 2 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. For example, in one or more embodiments, the content of lithium bis(oxalato)borate (LiBOB) can be equal to or greater than about 0.05 wt%, equal to or greater than about 0.1 wt%, or equal to or greater than about 0.5 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. The content of lithium bis(oxalato)borate (LiBOB) can be equal to or less than about 1 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. When the above range is satisfied, it can inhibit or reduce a sharp increase in initial resistance to improve the lifespan characteristics of the rechargeable lithium battery.

[0093] The first compound can be represented by Chemical Formula 1.

[0094] Chemical Formula 1

[0095]

[0096] In Chemical Formula 1,

[0097] R 1a ~ R 8a may each independently be hydrogen, a halide, a substituted or unsubstituted C1-C20 alkyl, a substituted or unsubstituted C2-C20 alkenyl, a substituted or unsubstituted C2-C20 alkynyl, a substituted or unsubstituted C3-C20 cycloalkyl, a substituted or unsubstituted C3-C20 cycloalkenyl, a substituted or unsubstituted C3-C20 cycloalkynyl, a substituted or unsubstituted C6-C30 aryl, or a substituted or unsubstituted C2-C30 heterocyclyl.

[0098] k can be 0 or 1.

[0099] The first compound can include at least one cyclic sulfonate compound. If (for example, when) k is 0, the first compound can have a pentagonal (for example, five-membered) ring structure; or if (for example, when) k is 1, the first compound can have a hexagonal (for example, six-membered) ring structure.

[0100] In one or more embodiments, the first compound can include at least one selected from a compound represented by Chemical Formula 1-1 and a compound represented by Chemical Formula 1-2.

[0101] Chemical Formula 1-1

[0102]

[0103] Chemical Formula 1-2

[0104]

[0105] In Chemical Formula 1-1 and Chemical Formula 1-2,

[0106] R 1a ~R 8a may be each independently hydrogen, a halide, a substituted or unsubstituted C1-C20 alkyl, a substituted or unsubstituted C2-C20 alkenyl, a substituted or unsubstituted C2-C20 alkynyl, a substituted or unsubstituted C3-C20 cycloalkyl, a substituted or unsubstituted C3-C20 cycloalkenyl, a substituted or unsubstituted C3-C20 cycloalkynyl, a substituted or unsubstituted C6-C30 aryl, or a substituted or unsubstituted C2-C30 heterocyclyl.

[0107] In one or more embodiments, in Chemical Formula 1-1 and Chemical Formula 1-2, all of R 1a ~R 8a may be hydrogen.

[0108] In one or more embodiments, the first compound can include at least one selected from a compound represented by Chemical Formula 1-1-1 and a compound represented by Chemical Formula 1-2-1.

[0109] Chemical Formula 1-1-1

[0110]

[0111] Chemical Formula 1-2-1

[0112]

[0113] Since the first compound includes a cyclic sulfonate compound, a film can be formed on the positive electrode. The film formed on the positive electrode can inhibit or reduce oxidative decomposition of the non-aqueous organic solvent at the positive electrode in a high-temperature environment. An oxalate moiety derived from lithium bis(oxalato)borate (LiBOB) can react with moisture in the electrolyte at a high voltage to generate a gas (carbon dioxide, CO2). When the first compound forms an oxidation film on the positive electrode, the reaction of the oxalate moiety at the positive electrode with the moisture in the electrolyte can be prevented or reduced, and thus the generation of the gas can be inhibited or reduced.

[0114] In one or more embodiments, the content of the first compound can be about 0.01 wt% to about 5 wt% relative to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. For example, in one or more embodiments, the content of the first compound can be equal to or greater than about 0.1 wt%, equal to or greater than about 0.5 wt%, or equal to or greater than about 1 wt% relative to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. The content of the first compound can be equal to or less than about 3 wt% or equal to or less than about 2 wt% relative to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. When the above range is satisfied, it can be improved in terms of suppression of gas generation.

[0115] The second compound can be represented by Chemical Formula 2.

[0116] Chemical Formula 2

[0117]

[0118] In Chemical Formula 2,

[0119] A 1 may be O or C(R 1b )(R 2b ),

[0120] A 2 may be O or C(R 3b )(R 4b ),

[0121] B 1 may be C(R 5b )(R 6b ) or carbonyl,

[0122] B 2 may be C(R 7b )(R 8b ) or carbonyl,

[0123] B 3 may be C(R 9b )(R 10b ) or carbonyl,

[0124] B 4 may be C(R 11b )(R 12b ) or carbonyl,

[0125] R 1b ~ R 12beach independently hydrogen, halo, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C3-C20 cycloalkynyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C2-C30 heterocyclyl,

[0126] n1, n2, m1, and m2 can each independently be an integer of 0 or 1, and

[0127] n1, m1, n2, and m2 can satisfy the following relationship: n1 + m1 ≥ 1 and n2 + m2 ≥ 1. For example, if (e.g., when) n1 + m1 = 1, the ring including B 1 may be a five-membered ring; if (e.g., when) n1 + m1 = 2, the ring including B 1 may be a six-membered ring. Also, for example, if (e.g., when) n2 + m2 = 1, the ring including B 3 may be a five-membered ring; if (e.g., when) n2 + m2 = 2, the ring including B 3 may be a six-membered ring.

[0128] The second compound can be a bicyclic sulfates compound or a bicyclic sulfonates compound. The second compound can be reduced even at 2.7 V to form a reduction film on the negative electrode. The film formed from the second compound can inhibit or reduce an increase in resistance to exhibit an aspect of output characteristics improvement.

[0129] In one or more embodiments, the second compound can include at least one selected from the group consisting of compounds represented by Chemical Formulae 2-1 to 2-4.

[0130] Chemical Formula 2-1

[0131]

[0132] Chemical Formula 2-2

[0133]

[0134] Chemical Formula 2-3

[0135]

[0136] Chemical Formula 2-4

[0137]

[0138] In Chemical Formulae 2-1 to 2-4,

[0139] B1 may be C(R 5b )(R 6b ) or carbonyl,

[0140] B 2 may be C(R 7b )(R 8b ) or carbonyl,

[0141] B 3 may be C(R 9b )(R 10b ) or carbonyl,

[0142] B 4 may be C(R 11b )(R 12b ) or carbonyl, and

[0143] R 1b to R 12b may each independently be hydrogen, halo, substituted or unsubstituted C1-C20alkyl, substituted or unsubstituted C2-C20alkenyl, substituted or unsubstituted C2-C20alkynyl, substituted or unsubstituted C3-C20cycloalkyl, substituted or unsubstituted C3-C20cycloalkenyl, substituted or unsubstituted C3-C20cycloalkynyl, substituted or unsubstituted C6-C30aryl, or substituted or unsubstituted C2-C30heterocyclyl.

[0144] In one or more embodiments, the second compound can include at least one selected from the group consisting of Chemical Formula 2-1-1 to Chemical Formula 2-4-1.

[0145] Chemical Formula 2-1-1

[0146]

[0147] Chemical Formula 2-2-1

[0148]

[0149] Chemical Formula 2-3-1

[0150]

[0151] Chemical Formula 2-4-1

[0152]

[0153] In Chemical Formula 2-1-1 to Chemical Formula 2-4-1,

[0154] R 1b to R 12beach independently hydrogen, halo, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C3-C20 cycloalkynyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C2-C30 heterocyclyl.

[0155] In one or more embodiments, the second compound can include at least one selected from the compounds listed in Group 1.

[0156] Group 1

[0157]

[0158] Since the second compound includes a bicyclic sulfate compound and / or a bicyclic sulfonate compound, a film can be formed on the negative electrode. The film formed on the negative electrode can cause a decrease in the initial resistance and the resistance increase rate. Under high voltage operation, transition metals included in the positive electrode active material can be dissolved into the electrolyte. The dissolved transition metal ions can be electrodeposited on the negative electrode, as a result, the negative electrode can be deteriorated, thereby increasing the initial resistance and the resistance increase rate. When the second compound forms a reduction film on the negative electrode, the electrodeposition of the dissolved transition metal ions can be prevented or reduced, and thus the initial resistance and the resistance increase rate can be decreased.

[0159] In one or more embodiments, the content of the second compound can be about 0.01 wt% to about 5 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. For example, in one or more embodiments, the content of the second compound can be equal to or greater than about 0.1 wt%, equal to or greater than about 0.5 wt%, or equal to or greater than about 1 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. The content of the second compound can be equal to or less than about 3 wt% or equal to or less than about 2 wt% with respect to 100 wt% of the total weight of the electrolyte for the rechargeable lithium battery. When the above range is satisfied, the initial resistance and the resistance increase rate can be decreased.

[0160] The electrolyte for the rechargeable lithium battery according to one or more embodiments can include lithium bis(oxalato)borate (LiBOB) and the first compound in a weight ratio of about 1:1 to about 1:20. For example, in one or more embodiments, lithium bis(oxalato)borate (LiBOB) and the first compound can be included in a weight ratio of about 1:1 to about 1:10, about 1:1 to about 1:4, or about 1:1 to about 1:2. When the above range is satisfied, the first compound can sufficiently prevent or reduce the reaction of the oxalate moiety with moisture in the electrolyte under high voltage, thereby inhibiting or reducing gas generation.

[0161] The electrolyte for a rechargeable lithium battery according to one or more embodiments can include lithium bis(oxalato)borate (LiBOB) and a second compound in a weight ratio of about 1:1 to about 1:20. For example, in one or more embodiments, lithium bis(oxalato)borate (LiBOB) and a second compound can be included in a weight ratio of about 1:1 to about 1:10, about 1:1 to about 1:4, or about 1:1 to about 1:2. When the above range is satisfied, the second compound can sufficiently prevent or reduce the electrodeposition of transition metal ions eluted from the positive electrode active material on the negative electrode, thereby reducing the initial resistance and the resistance increase rate.

[0162] The electrolyte for a rechargeable lithium battery according to one or more embodiments can include a first compound and a second compound in a weight ratio of about 1:0.2 to about 1:5. For example, in one or more embodiments, a first compound and a second compound can be included in a weight ratio of about 1:0.5 to about 1:2. When the above range is satisfied, an oxidation film can be formed on the positive electrode, and a reduction film can be formed on the negative electrode, and thus it can inhibit or reduce gas generation and reduce the initial resistance and the resistance increase rate. The rechargeable lithium battery according to one or more embodiments can be configured to be operable even at a high voltage equal to or greater than about 4.2 V.

[0163] Rechargeable lithium battery

[0164] Based on the shape of the rechargeable lithium battery, the rechargeable lithium battery can be classified into a cylindrical battery, a prismatic battery, a pouch (type) battery, or a coin (type) battery. Figures 2 to 5 Each is a simplified diagram illustrating a rechargeable lithium battery according to one or more embodiments, Figure 2 illustrating a cylindrical battery, Figure 3 illustrating a prismatic battery, and Figure 4 and Figure 5 Each illustrates a pouch (type) battery. Referring to Figures 2 to 5 , the rechargeable lithium battery 100 can include an electrode assembly 40 in which a separator 30 is interposed between a positive electrode 10 and a negative electrode 20, and can further include a case 50 in which the electrode assembly 40 is accommodated. The positive electrode 10, the negative electrode 20, and the separator 30 can be impregnated in and / or with an electrolyte. In some embodiments, the rechargeable lithium battery 100 can include a sealing member 60 that seals the case 50, as explained in Figure 2 . In some embodiments, as explained in Figure 3 , the rechargeable lithium battery 100 can include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. In some embodiments, as explained in Figure 4 and Figure 5As shown in FIG. 1, the rechargeable lithium battery 100 can include an electrode tab 70 (or a positive electrode tab 71 and a negative electrode tab 72) serving as an electrical path to externally guide the electric current generated in the electrode assembly 40.

[0165] The rechargeable lithium battery according to one or more embodiments of the present disclosure can be applied to a car, a mobile phone, and / or any other electrical device, but embodiments of the present disclosure are not limited thereto.

[0166] Embodiments and comparative examples of the present disclosure will be described below. However, the following embodiments are merely examples, and the present disclosure is not limited to the embodiments discussed herein.

[0167] Embodiments and comparative examples

[0168] The electrolyte and the rechargeable lithium battery are each manufactured by the following methods.

[0169] Embodiment 1

[0170] (1) Preparation of electrolyte

[0171] 1.0 M LiPF6and 0.1 wt% of lithium bis(oxalato)borate (LiBOB) (the weight percentage of LiBOB is based on the total weight of 100 wt% of the electrolyte) were dissolved in a non-aqueous organic solvent including ethylene carbonate (EC), methyl ethyl carbonate (MEC), and dimethyl carbonate (DMC) mixed at a volume ratio of about 20:40:40, and an additive was added to prepare an electrolyte.

[0172] The additive was prepared by mixing a compound represented by Chemical Formula 1a in an amount of about 1 wt% with respect to the total weight of 100 wt% of the electrolyte and a compound represented by Chemical Formula 2a in an amount of about 1 wt% with respect to the total weight of 100 wt% of the electrolyte.

[0173] Chemical Formula 1a

[0174]

[0175] 1,4-butane sultone (CAS No.: 1633-83-6)

[0176] Chemical Formula 2a

[0177]

[0178] Preparation Example 1: Synthesis of a compound represented by Chemical Formula 2a

[0179] Reaction Scheme 1

[0180]

[0181] Step 1: Synthesis of Intermediate A

[0182] To a solvent containing tetrahydrofuran (THF) and dichloromethane (DCM, CH2Cl2) mixed at a volume ratio of 1:1 were added 68.0 g (0.499 mol) of pentaerythritol and 100 g of molecular sieves (4A type), followed by reflux for 20 minutes. Subsequently, 110 mL (2.8 equivalents, 1.40 mol) of thionyl chloride (SOCl2) was added, followed by reflux for 8 hours until the pentaerythritol was completely reacted, to obtain a light yellow solution. The obtained light yellow solution was filtered and concentrated to obtain a residue containing a light yellow solid. 1 L of a saturated sodium bicarbonate (saturated NaHCO3) solution was directly added to the obtained residue at a rate that minimizes foaming. The obtained suspension was vigorously stirred for 20 minutes. Subsequently, the suspension was filtered, and the solid filtered therefrom was added to 1 L of purified water to prepare a mixture. The prepared mixture was vigorously stirred for 20 minutes, filtered under reduced pressure (suction filtration), and dried in air to recover 104.61 g of Intermediate A (0.458 mol, yield: 92%).

[0183] Synthesis of Intermediate A 1 H and 13 The1C NMR data were consistent with the literature values.

[0184] Step 2: Synthesis of a compound represented by Chemical Formula 2a

[0185] The compound represented by Chemical Formula 2a was synthesized from Intermediate A in the method disclosed in Canadian Journal of Chemistry, 79, 2001, p. 1042, as shown in Reaction Scheme 1. The relevant content thereof is incorporated herein by reference in its entirety.

[0186] The synthesized compound was recrystallized in a solvent containing 1,2-dichloroethane and acetonitrile mixed at a volume ratio of 2:1 to obtain the target compound.

[0187] (2) Manufacture of rechargeable lithium battery

[0188] LiNi 0.88 Co 0.07 Al 0.05 O2, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed at a weight ratio of 97:2:1, and the mixture was dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0189] The positive electrode active material slurry was coated on an Al foil having a thickness of 14 μm, dried at 110°C, and then pressed to manufacture a positive electrode.

[0190] The artificial graphite and the silicon-carbon composite, which are the negative electrode active material, are mixed in a weight ratio of 93:7, the styrene-butadiene rubber, which is the binder, and the carboxymethyl cellulose, which is the tackifier, are mixed in a weight ratio of 97:1:2, and the mixture is distributed in distilled water to prepare a negative electrode active material slurry.

[0191] The silicon-carbon composite includes a core including artificial graphite and silicon particles, and coal tar pitch coated on a surface of the core.

[0192] The negative electrode active material slurry is coated on a Cu foil having a thickness of 10 μm, dried at 110°C, and then pressed to manufacture a negative electrode.

[0193] The positive electrode, the negative electrode, and a polyethylene separator having a thickness of 25 μm are assembled to manufacture an electrode assembly, and an electrolyte is introduced to manufacture a rechargeable lithium battery of a prismatic battery cell type or kind having a thickness of 10 mm.

[0194] Embodiment 2

[0195] A rechargeable lithium battery is manufactured in substantially the same manner as in Embodiment 1, except that 0.5 wt% of lithium bis(oxalato)borate (LiBOB) is dissolved in the non-aqueous organic solvent.

[0196] Embodiment 3

[0197] A rechargeable lithium battery is manufactured in substantially the same manner as in Embodiment 1, except that 1 wt% of lithium bis(oxalato)borate (LiBOB) is dissolved in the non-aqueous organic solvent.

[0198] Embodiment 4

[0199] A rechargeable lithium battery is manufactured in substantially the same manner as in Embodiment 2, except that the additive is prepared by mixing the compound represented by Chemical Formula 2a in an amount of 0.1 wt% with respect to the total weight of 100 wt% of the electrolyte.

[0200] Embodiment 5

[0201] A rechargeable lithium battery is manufactured in substantially the same manner as in Embodiment 2, except that the additive is prepared by mixing the compound represented by Chemical Formula 2a in an amount of 2 wt% with respect to the total weight of 100 wt% of the electrolyte.

[0202] Embodiment 6

[0203] A rechargeable lithium battery is manufactured in substantially the same manner as in Embodiment 2, except that the additive is prepared by mixing the compound represented by Chemical Formula 1a in an amount of 0.1 wt% with respect to the total weight of 100 wt% of the electrolyte.

[0204] Embodiment 7

[0205] A rechargeable lithium battery was manufactured in substantially the same manner as Embodiment 2, except that the additive was prepared by mixing the compound represented by Chemical Formula 1a in an amount of 2 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0206] Embodiment 8

[0207] A rechargeable lithium battery was manufactured in substantially the same manner as Embodiment 1, except that the additive was prepared by mixing the compound represented by Chemical Formula 2b in an amount of 1 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0208] Chemical Formula 2b

[0209]

[0210] Preparation Example 2: Synthesis of the compound represented by Chemical Formula 2b

[0211] Reaction Scheme 2

[0212]

[0213] Step (1): Synthesis of Intermediate B

[0214] 50 g (0.154 mol) of tribromoneopentyl alcohol was added dropwise to a solution containing 10.34 g (0.156 mol) of KOH dissolved in 200 mL of ethanol, and then reacted by reflux for 0.5 hours. After cooling the resulting product to room temperature with KBr, the residue obtained by evaporating the ethanol was distilled to obtain 28 g (0.115 mol) of Intermediate B (3,3-bis(bromomethyl)oxetane).

[0215] Step (2): Synthesis of Intermediate C

[0216] 28 g (0.115 mol) of Intermediate B (3,3-bis(bromomethyl)oxetane) was dissolved in a solution containing 28 mL of water dissolved in 94 mL of methanol, and then added dropwise to a solution containing 44.8 g (0.358 mol) of Na2SO3 dissolved in 252 mL of water. The mixed solution was refluxed for 3.5 hours, and the solvent was removed from the mixed solution including Intermediate C, NaBr, and Na2SO3 under vacuum. The mixture from which the solvent was removed was treated with HCl at room temperature, and then filtered with NaCl.

[0217] Step (3): Synthesis of the compound represented by Chemical Formula 2b

[0218] The sulfonic acid solution was evaporated under vacuum, and then the oil remaining after the evaporation of the sulfonic acid solution was heated at 210°C to 220°C for 2 hours under a pressure of 2 mmHg (i.e., 2 torr). The remaining substance was refluxed with acetone, cooled to room temperature, and then filtered. After the remaining solid was extracted with ethyl acetate in a Soxhlet apparatus, the ethyl acetate suspension containing the compound represented by Chemical Formula 2b was cooled to room temperature and then filtered (yield: 10 g).

[0219] Embodiment 9

[0220] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 8, except that 0.5 wt% of lithium bis(oxalato)borate (LiBOB) was dissolved in the nonaqueous organic solvent.

[0221] Embodiment 10

[0222] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 8, except that 1 wt% of lithium bis(oxalato)borate (LiBOB) was dissolved in the nonaqueous organic solvent.

[0223] Embodiment 11

[0224] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 9, except that the additive was prepared by mixing the compound represented by Chemical Formula 2b in an amount of 0.1 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0225] Embodiment 12

[0226] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 9, except that the additive was prepared by mixing the compound represented by Chemical Formula 2b in an amount of 2 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0227] Embodiment 13

[0228] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 9, except that the additive was prepared by mixing the compound represented by Chemical Formula 1a in an amount of 0.1 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0229] Embodiment 14

[0230] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 9, except that the additive was prepared by mixing the compound represented by Chemical Formula 1a in an amount of 2 wt% with respect to the total weight of 100 wt% of the electrolyte solution.

[0231] Comparative Example 1

[0232] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no additive was added.

[0233] Comparative Example 2

[0234] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no lithium bis(oxalato)borate (LiBOB) was added and no compound represented by Chemical Formula 1a was added as an additive.

[0235] Comparative Example 3

[0236] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no lithium bis(oxalato)borate (LiBOB) was added and no compound represented by Chemical Formula 2a was added as an additive.

[0237] Comparative Example 4

[0238] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no compound represented by Chemical Formula 1a was added as an additive.

[0239] Comparative Example 5

[0240] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no compound represented by Chemical Formula 2a was added as an additive.

[0241] Comparative Example 6

[0242] A rechargeable lithium battery was manufactured in substantially the same manner as in Embodiment 2, except that no lithium bis(oxalato)borate (LiBOB) was added.

[0243] Table 1 lists the compositions according to the embodiments and comparative examples.

[0244] Table 1

[0245]

[0246] * Compound n indicates a compound represented by Chemical Formula n.

[0247] ** The symbol "-" indicates that no additive was added.

[0248] Evaluation 1: Room temperature life characteristics and DC resistance increase rate

[0249] Each of the rechargeable lithium batteries manufactured according to Embodiments 1 to 14 and Comparative Examples 1 to 6 was charged and discharged once at a 0.2C rate, so as to measure the charge and discharge capacity (initial capacity).

[0250] Each of the rechargeable lithium batteries manufactured according to Embodiments 1 to 14 and Comparative Examples 1 to 6 was then subjected to 100 cycle charges and discharges at a rate of 0.5C in the range of 2.75 to 4.25 V at room temperature (25°C), and then the change in discharge capacity was measured to calculate the capacity retention rate, i.e., the ratio of the 100-cycle discharge capacity to the initial capacity, which is shown in Table 2 as the capacity retention rate (%).

[0251] After allowing each of the rechargeable lithium batteries according to Embodiments 1 to 14 and Comparative Examples 1 to 6 to measure the initial DC internal resistance (DCIR) thereof with ΔV / ΔI (voltage change / current change), the maximum energy state inside the battery became a fully charged state (SOC 100%), and the battery was stored in this state at room temperature (25°C) for 30 days, and then the DC internal resistance was measured to calculate the DCIR increase rate (%) according to Equation 1, and Table 2 lists the following results.

[0252] Equation 1

[0253] DCIR increase rate (%) = (DCIR after 30 days / initial DCIR) x 100

[0254] Evaluation 2: High-temperature DC resistance increase rate

[0255] Each of the rechargeable lithium batteries manufactured according to Embodiments 1 to 14 and Comparative Examples 1 to 6 was charged and discharged once at a rate of 0.2C, thereby measuring the charge and discharge capacity (initial capacity).

[0256] Each of the rechargeable lithium batteries manufactured according to Embodiments 1 to 14 and Comparative Examples 1 to 6 was then subjected to 100 cycle charges and discharges at a rate of 0.5C in the range of 2.75 to 4.25 V at high temperature (60°C), and then the change in discharge capacity was measured to calculate the capacity retention rate, i.e., the ratio of the 100-cycle discharge capacity to the initial capacity.

[0257] In addition, each of the rechargeable lithium batteries was recharged to 4.2 V at a rate of 0.2C under constant current, 0.05C cutoff, and constant voltage conditions, and discharged to 3.0 V at a rate of 0.2C under constant current conditions, thereby measuring the discharge capacity. The charge and discharge characteristics at this time are referred to as recovery characteristics. Here, the charge and discharge capacities were measured to calculate the ratio of the discharge capacity to the initial capacity, and the results are shown in Table 2 as the capacity recovery rate (%).

[0258] After allowing each of the rechargeable lithium batteries according to Embodiments 1 to 14 and Comparative Examples 1 to 6 to measure its initial direct current internal resistance (DCIR) with AV / AI (voltage change / current change), the maximum energy state of the battery inside becomes a fully charged state (SOC 100%), the battery is stored at a high temperature (60°C) for 30 days in this state, then the direct current internal resistance is measured, the DCIR increase rate (%) is calculated according to Equation 1, and Table 2 lists the following results.

[0259] Equation 1

[0260] DCIR increase rate (%) = (DCIR after 30 days / initial DCIR) x 100

[0261] Evaluation 3: High-temperature gas generation

[0262] After each of the rechargeable lithium batteries according to Embodiments 1 to 14 and Comparative Examples 1 to 6 is stored at 60°C for 30 days, the thickness increase rate (%) is calculated according to Equation 2, and the results are listed in Table 2.

[0263] [Equation 2]

[0264] Thickness increase rate (%) = (cell thickness after 30 days / initial cell thickness) x 100

[0265] Table 2

[0266]

[0267] Referring to Table 2, it can be found that each of the rechargeable lithium batteries according to Embodiments 1 to 14 has excellent or appropriate capacity retention and resistance increase suppression effects at room temperature (25°C), and has excellent or appropriate capacity recovery and resistance increase suppression effects at a high temperature (60°C), compared to the rechargeable lithium batteries according to Comparative Examples 1 to 6. That is, each of the rechargeable lithium batteries according to Embodiments 1 to 14 has excellent or appropriate capacity retention and resistance increase suppression effects at room temperature (25°C), compared to the rechargeable lithium batteries in Comparative Examples 1 to 6. In addition, they also exhibit excellent or appropriate capacity recovery and resistance increase suppression effects at a high temperature (60°C).

[0268] Still referring to Table 2, it can be found that each of the rechargeable lithium batteries according to Embodiments 1 to 14 has a thickness increase rate at a high temperature (60°C), which is not high, compared to Comparative Examples 1, 2, and 4. It can be determined that lithium bis(oxalato)borate (LiBOB), the second compound, and the first compound are all included, so that the rechargeable lithium battery can have excellent or appropriate storage characteristics, and swelling phenomena caused by suppressing gas generation are mitigated.

[0269] The electrolyte for a rechargeable lithium battery according to one or more embodiments can be used to realize a rechargeable lithium battery in which an increase in resistance under high-temperature storage is suppressed or reduced and stability and life characteristics are excellent or appropriate.

[0270] In the present disclosure, expressions such as "at least one of," "one or more of," and "selected from the group consisting of" when preceding the list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, "at least one of a, b, and c," "at least one selected from a, b, and c," "at least one selected from the group consisting of a, b, and c," "at least one of a to c," and the like can indicate only a, only b, only c, both a and b (e.g., at the same time), both a and c (e.g., at the same time), both b and c (e.g., at the same time), all of a, b, and c, or variations thereof. " / " used herein can be interpreted as "and" or "or" depending on the situation.

[0271] In the context of the present disclosure, and unless otherwise defined, the terms "use," "using," and "used" can be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively.

[0272] In the present disclosure, the term "group" used herein refers to a group of the periodic table of elements according to the 1-18 group system of the International Union of Pure and Applied Chemistry ("IUPAC").

[0273] The terms "substantially," "about," and similar terms used herein are used as an approximation term and not as an exact term, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art. "About" or "approximately," as used in the present disclosure, also includes a recited value and a range of acceptable deviations from the recited value as determined by one of ordinary skill in the art considering the measurement and the error in measurement associated with the particular quantity being measured (e.g., limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0274] Any numerical range recited herein is intended to include all sub-ranges of the same whole number precision subsumed within the recited range. For example, a range from 1.0 to 10.0 is intended to include all sub-ranges, both including and

[0275] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to embodiments of the present disclosure described herein can be implemented with 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 apparatus can be formed on one integrated circuit (IC) chip or on separate IC chips. Further, various components of the apparatus can be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on one substrate. Further, various components of the apparatus can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functions described herein. The computer program instructions are stored in a memory, which can be implemented in a computing device using standard memory devices, such as, for example, random access memory (RAM). The computer program instructions can also be stored in other non-transitory computer readable media such as, for example, a CD-ROM or a flash drive, etc. Also, those skilled in the art will appreciate that functions of various computing devices can be combined or integrated into a single computing device, or functions of a single computing device can be distributed across one or more other computing devices

[0276] In view of the entire disclosure, those skilled in the art will appreciate that each appropriate feature of various embodiments of the present disclosure can be combined in part or in whole, and can be technically linked and operated in various appropriate ways, and each embodiment can be implemented independently of or in combination with each other in any appropriate way, unless otherwise specified or implied.

[0277] While the present disclosure has been described in connection with the preferred embodiments of the various aspects of the disclosure, it is to be understood that other suitable embodiments can be used without departing from the spirit and scope of the disclosure. Therefore, the present disclosure should not be understood to be limited to the specific embodiments described and shown, and it is therefore contemplated that those in the art can arrange and otherwise set up the disclosure in other specific embodiments and hexploits the present disclosure without departing from the spirit and scope of the disclosure.

Claims

1. An electrolyte comprising: a non-aqueous organic solvent; a lithium salt; lithium bis(oxalato)borate; a first compound represented by Chemical Formula 1; and a second compound represented by Chemical Formula 2, Chemical Formula 1 wherein, in Chemical Formula 1, R 1a ~R 8a each independently hydrogen, halo, substituted or unsubstituted C1-C20alkyl, substituted or unsubstituted C2-C20alkenyl, substituted or unsubstituted C2-C20alkynyl, substituted or unsubstituted C3-C20cycloalkyl, substituted or unsubstituted C3-C20cycloalkenyl, substituted or unsubstituted C3-C20cycloalkynyl, substituted or unsubstituted C6-C30aryl, or substituted or unsubstituted C2-C30heterocyclyl, and k is 0 or 1, Chemical Formula 2 wherein, in Chemical Formula 2, A 1 is O or C(R 1b )(R 2b ), A 2 is O or C(R 3b )(R 4b ), B 1 C(R 5b )(R 6b ) or carbonyl, B 2 C(R 7b )(R 8b ) or carbonyl, B 3 C(R 9b )(R 10b ) or carbonyl, B 4 C(R 11b )(R 12b ) or carbonyl, R 1b ~R 12b each independently hydrogen, halo, substituted or unsubstituted C1-C20alkyl, substituted or unsubstituted C2-C20alkenyl, substituted or unsubstituted C2-C20alkynyl, substituted or unsubstituted C3-C20cycloalkyl, substituted or unsubstituted C3-C20cycloalkenyl, substituted or unsubstituted C3-C20cycloalkynyl, substituted or unsubstituted C6-C30aryl, or substituted or unsubstituted C2-C30heterocyclyl, each of n1, n2, m1, and m2 is independently an integer of 0 or 1, and n1+m1≥1 and n2+m2≥1, "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, and wherein the electrolyte is used for a rechargeable lithium battery. 2.The electrolyte of claim 1, wherein the amount of the lithium bis(oxalato)borate is 0.01-2 wt% with respect to 100 wt% of the total weight of the electrolyte. 3.The electrolyte of claim 1, wherein the amount of the first compound is 0.01-5 wt% with respect to 100 wt% of the total weight of the electrolyte. 4.The electrolyte of claim 1, wherein the first compound comprises at least one selected from the group consisting of a compound represented by Chemical Formula 1-1 and a compound represented by Chemical Formula 1-2, Chemical Formula 1-1 Chemical Formula 1-2 In Chemical Formula 1-1 and Chemical Formula 1-2, R 1a ~R 8a each independently is the same as defined in Chemical Formula 1. 5.The electrolyte of claim 1, wherein the first compound comprises at least one selected from the group consisting of a compound represented by Chemical Formula 1-1-1 and a compound represented by Chemical Formula 1-2-1, Chemical Formula 1-1-1 Chemical Formula 1-2-1 6.The electrolyte of claim 1, wherein the amount of the second compound is 0.01-5 wt% with respect to 100 wt% of the total weight of the electrolyte. 7.The electrolyte of claim 1, wherein the second compound comprises at least one selected from the group consisting of a compound represented by Chemical Formula 2-1, Chemical Formula 2-2, Chemical Formula 2-3, and Chemical Formula 2-4, Chemical Formula 2-1 Chemical Formula 2-2 Chemical Formula 2-3 Chemical Formula 2-4 In Chemical Formula 2-1 to Chemical Formula 2-4, B 1 ~B 4 and R 1b ~R 4b each independently is the same as defined in Chemical Formula 2. 8.The electrolyte of claim 1, wherein the second compound comprises at least one selected from the group consisting of a compound represented by Chemical Formula 2-1-1, Chemical Formula 2-2-1, Chemical Formula 2-3-1, and Chemical Formula 2-4-1, Chemical Formula 2-1-1 Chemical Formula 2-2-1 Chemical Formula 2-3-1 Chemical Formula 2-4-1 In Chemical Formula 2-1-1 to Chemical Formula 2-4-1, R 1b ~R 12b each independently is the same as defined in Chemical Formula 2. 9.The electrolyte of claim 1, wherein the second compound comprises at least one selected from the group consisting of compounds listed in Group 1, Group 1 10.The electrolyte of claim 1, wherein the weight ratio of the lithium bis(oxalato)borate and the first compound is 1:1-1:

20. 11.The electrolyte of claim 1, wherein the weight ratio of the lithium bis(oxalato)borate and the second compound is 1:1-1:

20.

12. The electrolyte of claim 1, wherein the weight ratio of the first compound and the second compound is 1:0.2 to 1:

5.

13. The electrolyte of claim 1, wherein the non-aqueous organic solvent comprises a carbonate-based solvent.

14. The electrolyte of claim 13, wherein the carbonate-based solvent comprises dimethyl carbonate, ethyl methyl carbonate, and ethylene carbonate.

15. The electrolyte of claim 1, wherein the concentration of the lithium salt ranges from 0.1 M to 2.0 M.

16. 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 15.

17. The rechargeable lithium battery of claim 16, wherein the positive electrode active material comprises a compound represented by Chemical Formula 3, Chemical Formula 3 in Chemical Formula 3, 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, X comprises at least one selected from Al, Mn, Cr, Fe, Mg, Sr, V, and a rare earth element, and D comprises at least one selected from F, S, and P.

18. The rechargeable lithium battery of claim 16, wherein the positive electrode further comprises a positive electrode current collector, and the positive electrode current collector comprises an Al foil.

19. The rechargeable lithium battery of claim 16, wherein the negative electrode active material comprises at least one of a carbon-based negative electrode active material, a Sn-based negative electrode active material, and a Si-based negative electrode active material.

20. The rechargeable lithium battery of claim 16, wherein the rechargeable lithium battery is configured to operate even at a high voltage equal to or greater than 4.2 V. ​

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