Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte and a rechargeable lithium battery including the same. Electrolyte including non-aqueous organic solvent, lithium salt, first additive including compound represented by chemical formula 1, and second additive, chemical formula 1 # imgabs0 #

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0034010, filed on March 11, 2024, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] According to one or more embodiments, the present disclosure relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. Background Art

[0004] Recently, with the rapid popularization of electronic devices using batteries (such as mobile phones, laptop computers, electric vehicles, etc.), the desire or demand for rechargeable lithium batteries with relatively high energy density and relatively high capacity has increased rapidly. Therefore, intensive research has been conducted to improve the characteristics of rechargeable lithium batteries.

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode and the negative electrode each include an active material into which (for example, lithium ions) can be intercalated and deintercalated. For example, if (for example, when) lithium ions are intercalated and deintercalated, the rechargeable lithium battery generates electrical energy due to oxidation and reduction reactions.

[0006] Lithium salts dissolved in non-aqueous organic solvents serve as electrolytes for rechargeable lithium batteries. The performance characteristics of rechargeable lithium batteries are exhibited through complex reactions between the positive electrode and the electrolyte and / or between the negative electrode and the electrolyte. Accordingly, selecting a suitable or appropriate electrolyte is an important variable for improving the performance characteristics of rechargeable lithium batteries. Summary of the Invention

[0007] One or more aspects relate to an electrolyte for a rechargeable lithium battery having improved impregnation (eg, into an electrode (eg, a negative electrode)).

[0008] One or more aspects relate to a rechargeable lithium battery including an electrolyte as described herein.

[0009] 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.

[0010] According to one or more embodiments of the present disclosure, an electrolyte for a rechargeable lithium battery includes: a non-aqueous organic solvent; a lithium salt; and a first additive including a compound represented by Chemical Formula 1 (eg, as shown).

[0011] Chemical formula 1

[0012]

[0013] In Chemical Formula 1, R may be a substituted or unsubstituted branched C3-C15 alkyl group, and n may be an integer of 5-10.

[0014] According to one or more embodiments of the present disclosure, a rechargeable lithium battery includes: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0016] Figures 2 to 5 Simplified cross-sectional views each showing a rechargeable lithium battery according to one or more embodiments of the present disclosure are illustrated.

[0017] Figure 6 Images showing the results of impregnation test of the electrolytes according to Comparative Examples 1 to 3 and Example Embodiments 1 to 4 are illustrated.

[0018] Figure 7 Graphs showing results of thickness of rechargeable lithium batteries according to Comparative Examples 1 to 3 and Example Embodiments 1 to 4 are explained. DETAILED DESCRIPTION

[0019] In order to fully understand the configuration and effects of the present disclosure, some embodiments of the present disclosure will be described with reference to the attached drawings. However, it should be noted that the present disclosure is not limited to the exemplary embodiments and can be implemented in one or more suitable forms. On the contrary, the exemplary embodiments are provided only to disclose the present disclosure and to enable those skilled in the art to fully understand the scope of the present disclosure. One or more example embodiments of the present disclosure are illustrated in the attached drawings, wherein the same reference numerals refer to the same elements throughout the text, and their repeated description may not be provided. In the drawings, for clarity, the thickness of layers, films, plates, areas, etc. is exaggerated.

[0020] In this description, it will be understood that if (for example, when) an element is referred to as being on another element, the element may be directly on the other element, or intervening elements may be present therebetween. In the drawings, the size (for example, thickness) of some components is exaggerated for the purpose of effectively explaining the technical content. Throughout the specification, the same reference numerals refer to the same elements.

[0021] Unless otherwise specifically stated in this description, expressions in the singular may include expressions in the plural. In some embodiments, unless otherwise specifically stated, the phrase "A or B" may indicate "A but not B", "B but not A", and "A and B". The terms "comprises / includes" and / or "comprising / including" used in this description do not exclude the presence or addition of one or more other components. For example, terms such as "comprises", "comprise", "comprising", "includes", "including", "include", "having", "has" and / or "have" are intended to indicate the presence of specific features, quantities, steps (e.g., actions or tasks), elements and / or their (e.g., any appropriate) combination, and do not exclude the possibility of the presence or addition of one or more other features, quantities, steps (e.g., actions or tasks), elements and / or their (e.g., any appropriate) combination.

[0022] As used herein, the term "combination thereof" may refer to a mixture, stack, composite, copolymer, alloy, blend, or reaction product of the components.

[0023] In one or more embodiments, the term “layer” herein includes not only a shape formed on the entire surface but also a shape formed on a partial surface if (for example, when) viewed from a plan view.

[0024] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe one or more appropriate elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Thus, a first element, component, region, layer, or portion described herein could be referred to as a second element, component, region, layer, or portion without departing from the teachings set forth herein.

[0025] As utilized herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," "one of," and "selected from," if (e.g., when) preceding / following a 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 through c," "at least one of a, b, and c," and "at least one selected from a, b, and c" may indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0026] Spatially relative terms, such as "below," "beneath," "below," "above," "on," etc., may be used herein to easily describe the relationship between one element or feature and another element or feature. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations illustrated in the drawings. For example, if (e.g., when) the device in the drawings is flipped, an element described as "below" or "beneath" other elements or features will be oriented "above" the other elements or features. Thus, the example term "below" may encompass both (e.g., simultaneously) orientations of above and below. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative terms used herein may be interpreted accordingly.

[0027] The terms used in this article are only used to describe the purpose of specific embodiments and are not intended to limit the present disclosure. Unless otherwise limited, all terms used in this article (including chemical terms, technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having the same meaning as their context in the relevant art and the present disclosure, and will not be interpreted in an ideal or overly formal sense.

[0028] Example embodiments are described herein with reference to cross-sectional views that are schematic representations of idealized embodiments. As such, variations from the illustrated shapes may be expected due to, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as limited to the specific shapes of the regions as illustrated herein, but rather as including deviations in shape that result from, for example, manufacturing. For example, a region illustrated or described as flat may typically have rough and / or nonlinear features. Moreover, illustrated sharp corners may be rounded. Therefore, the regions illustrated in the drawings are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the present claims.

[0029] The term "may" will be understood to refer to "one or more embodiments of the present disclosure," some of which include the described element and some of which exclude the element and / or include alternative elements. Similarly, optional language (such as "or") refers to "one or more embodiments of the present disclosure" that each include the corresponding enumerated item.

[0030] In this context, "consisting essentially of" means that any additional components will not substantially affect the chemical, physical, optical, or electrical properties of the target moiety.

[0031] Further, in this specification, the phrase “on a plane” or “plan view” means observing a target portion from the top, and the phrase “in a cross section” means observing a cross section formed by vertically cutting the target portion from the side.

[0032] As used herein, the terms "use," "using," and "used" may be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.

[0033] In the present description, unless otherwise limited, the term "substituted" may refer to a substituent or a compound in which at least one hydrogen is replaced by deuterium, a halide, a hydroxyl, 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, or a combination thereof.

[0034] In detail, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or a compound by deuterium, halogen, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C10 fluoroalkyl, or cyano. For example, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or a compound by deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. Alternatively, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or a compound by deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, or cyano. For example, the term "substituted" may mean that at least one hydrogen of a substituent or compound is replaced with deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0035] In the present description, the halogen atom may be, for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0036] Unless otherwise defined in the present description, the alkyl group may be a linear alkyl group or a branched alkyl group. The number of carbon atoms in the alkyl group may range from 1 to 30, 1 to 20, 1 to 10, or 1 to 6. The alkyl group may include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, tert-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl, 2-octyldecyl, n-undecyl, n-decyl, One or more of dialkyl, 2-ethyl-dodecyl, 2-butyl-dodecyl, 2-hexyl-dodecyl, 2-octyl-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl, 2-octylhexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, 2-ethyleicosyl, 2-butyleicosyl, 2-hexyleicosyl, 2-octyleicosyl, n-heneicosyl, n-docosyl, n-tricosyl, n-tetracosyl, n-pentacosyl, n-hexacosyl, n-heptacosyl, n-octacosyl, n-nonacosyl, and n-triacontyl, but the present disclosure is not limited thereto.

[0037] Figure 1 Description

[0038] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated. Figure 1 , a rechargeable lithium battery may 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 may be spaced and / or separated by a separator 30. The separator 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in the electrolyte ELL.

[0040] The electrolyte ELL may be a medium through which lithium ions are transferred between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, the lithium ions may move toward 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 may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 on the positive electrode current collector COL1. The positive electrode active material layer AML1 may include a positive electrode active material and may further include a binder and / or a conductive material.

[0043] For example, the positive electrode 10 may further include a component that may serve as a sacrificial positive electrode.

[0044] The amount of the positive electrode active material may range from about 90 wt % to about 99 wt % relative to 100 wt % of the positive electrode active material layer AML1. The amount of the binder and the conductive material may each independently range from about 0.5 wt % to about 5 wt % relative to 100 wt % of the positive electrode active material layer AML1.

[0045] The binder can be used to improve the attachment of the positive electrode active material particles to each other and also to improve the attachment of the positive electrode active material to the positive electrode current collector COL 1. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene oxide-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, or nylon, but the present disclosure is not limited thereto.

[0046] Conductive materials can be used to provide electrode conductivity, and any suitable conductive material that avoids causing chemical changes in the battery can be used as (e.g., constitutes) the conductive material of the battery. Conductive materials may include, for example: carbon-based materials such as at least one selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal powders or metal fibers including one or more of copper, nickel, aluminum, and silver (e.g., at least one selected from copper, nickel, aluminum, and silver); conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0047] An aluminum (Al) foil may be used as the positive electrode current collector COL1 , but the present disclosure is not limited thereto.

[0048] Positive electrode active material

[0049] The positive electrode active material in the positive electrode active material layer AML1 may include a compound that reversibly intercalates and deintercalates lithium (e.g., a lithiated intercalation compound). For example, the positive electrode active material may include at least one type of composite oxide including lithium and a metal selected from cobalt, manganese, nickel, or a combination thereof.

[0050] The composite oxide may be or include a lithium transition metal composite oxide, for example, a lithium nickel oxide (for example, a nickel cobalt aluminum (NCA) lithium composite oxide (for example, LiNiCoAlO2)), a lithium cobalt oxide, a lithium manganese oxide, a lithium iron phosphate compound, a cobalt-free nickel manganese oxide, or a combination thereof.

[0051] For example, the positive electrode active material may include a compound represented by (eg, represented by) at least one of the chemical formulae herein (eg, selected from at least one of the chemical formulae herein). a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 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, 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, 0<α<2), Li a Ni 1-b-c Mn b X cO 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 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, 0≤e≤0.1), Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1), Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5), Li (3-f) Fe2(PO4)3(0≤f≤2) and Li a FePO4(0.90≤a≤1.8).

[0052] In the chemical formula herein, A may be Ni, Co, Mn, or a combination thereof, X may be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, D may be O, F, S, P, or a combination thereof, G may be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, and L may be Ni, Co, Mn, Cr, Fe, Mg, La, Ce, Sr, V, or a combination thereof. 1 It can be Mn, Al or a combination thereof.

[0053] For example, based on (or relative to) 100 mol% of metals other than lithium in the lithium transition metal composite oxide, the positive electrode active material may be a high nickel-based positive electrode active material having a nickel content (e.g., amount) of about 80 mol% or more, about 85 mol% or more, about 90 mol% or more, about 91 mol% or more, or about 94 mol% or more and about 99 mol% or less. The high nickel-based positive electrode active material can achieve high capacity and is therefore applicable to high capacity and high energy density rechargeable lithium batteries.

[0054] Negative electrode 20

[0055] 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.

[0056] For example, the negative electrode active material layer AML2 may include a negative electrode active material in an amount of about 90 wt % to about 99 wt %, a binder in an amount of about 0.5 wt % to about 5 wt %, and a conductive material in an amount of about 0 wt % to about 5 wt %, based on 100 wt % of the negative electrode active material layer AML2.

[0057] The binder can be used to improve the attachment of the negative electrode active material particles to each other and also to improve the attachment of the negative electrode active material to the negative electrode current collector COL 2. The binder can include a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0058] The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0059] The aqueous binder may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol or a combination thereof.

[0060] If (for example, when) an aqueous binder is used as a binder in the negative electrode active material layer AML2, a cellulose compound capable of providing or increasing viscosity may be further included. The cellulose compound may include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may include Na, K, and / or Li.

[0061] The dry binder may include a fibrillable polymeric material such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0062] A conductive material (e.g., an electronic conductor) can be used to provide electrode conductivity, and any suitable conductive material that does not cause chemical changes in the battery can be used as the conductive material constituting the battery. For example, the conductive material can include: carbonaceous 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 of copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0063] The negative electrode current collector COL2 can 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, or a combination thereof.

[0064] Negative electrode active material

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

[0066] The material that reversibly intercalates and deintercalates lithium ions can include carbonaceous negative electrode active materials, for example, crystalline carbon, amorphous carbon, or a combination thereof. For example, crystalline carbon can include graphite, such as amorphous, flaky, lamellar, spherical, or fibrous natural or artificial graphite, and amorphous carbon can include soft carbon, hard carbon, mesophase pitch carbon, or calcined coke.

[0067] The lithium metal alloy can include an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0068] The material doped and undoped with lithium can include Si-based negative electrode active materials or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (except Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, or a combination thereof), or a combination thereof. Sn-based negative electrode active materials can include Sn, SnO2, SnO x (0 < x < 2), a Sn-based alloy, or a combination thereof.

[0069] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may have a structure in which amorphous carbon is coated on the surface of silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are aggregated and an amorphous carbon coating (shell) located on the surface of the secondary particles. Amorphous carbon may also be located between primary silicon particles, and, for example, primary silicon particles may be coated with amorphous carbon. Secondary particles may be dispersed in an amorphous carbon matrix.

[0070] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core including crystalline carbon and silicon particles, and may further include an amorphous carbon coating on the surface of the core.

[0071] A Si-based negative electrode active material or a Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material.

[0072] Diaphragm 30

[0073] Depending on the type or class of the rechargeable lithium battery, the separator 30 may be present between the positive electrode 10 and the negative electrode 20. The separator 30 may include one or more of a polyethylene separator, a polypropylene separator, and a polyvinylidene fluoride separator, and may have a structure of a multilayer separator thereof (such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and a polypropylene / polyethylene / polypropylene three-layer separator).

[0074] The separator 30 may include a porous substrate and a coating layer on one or opposite surfaces of the porous substrate, the coating layer including an organic material, an inorganic material, or a combination thereof.

[0075] The porous substrate may be a polymer layer comprising: one selected from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon); or a copolymer or mixture comprising two or more of the above-mentioned materials.

[0076] The organic material may include a polyvinylidene fluoride-based copolymer or a (meth)acrylic acid-based copolymer.

[0077] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, or combinations thereof, but the present disclosure is not limited thereto.

[0078] The organic material and the inorganic material may be present as a mixture in one coating layer, or may be present as a stack of a coating layer including an organic material and a coating layer including an inorganic material.

[0079] Electrolyte ELL

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

[0081] The non-aqueous organic solvent may serve as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0082] The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, an aprotic solvent, or a combination thereof.

[0083] The carbonate-based solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC) and / or butylene carbonate (BC).

[0084] The ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate (EP), propyl propionate (PP), decanoic acid lactone, mevalonolactone, valerolactone, or caprolactone.

[0085] The ether solvent may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran and / or tetrahydrofuran. The ketone solvent may include cyclohexanone. The aprotic solvent may include one or more selected from the following: a nitrile, such as R-CN (wherein R is a hydrocarbon group having a C2 to C20 linear, branched or cyclic structure, and may include a double bond, an aromatic ring or an ether group); an amide (such as dimethylformamide); a dioxolane (such as 1,3-dioxolane and / or 1,4-dioxolane); and / or sulfolane.

[0086] The nonaqueous organic solvent may be used alone or as a mixture of two or more species.

[0087] In some embodiments, if (eg, when) a carbonate-based solvent is used, cyclic carbonate and chain carbonate may be mixed and used, and the cyclic carbonate and chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0088] The lithium salt may be a material dissolved in a non-aqueous organic solvent, used as a lithium ion supply source in the battery, and plays a role in ensuring the basic operation of the rechargeable lithium battery and promoting the movement of lithium ions between the positive electrode and the negative electrode. For example, the lithium salt may include at least one selected from the following: LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are each independently a natural number between 1 and 20), LiCl, LiI, LiB(C2O4)2, lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB) and lithium difluorobis(oxalato)phosphate (Li[PF2(C2O4)2], LiDFBOP).

[0089] The lithium salt may have a concentration of about 0.1 M to about 2.0 M. If (for example, when) the lithium salt has a concentration within the range disclosed herein, the electrolyte may have suitable or appropriate conductivity and viscosity to exhibit excellent electrolyte performance and allow efficient movement of lithium ions.

[0090] Rechargeable lithium battery

[0091] Rechargeable lithium batteries may be classified into cylindrical batteries, prismatic batteries, pouch-type or -like batteries, and coin-type or -like batteries based on their shapes. Figures 2 to 5 Simplified cross-sectional views each showing a rechargeable lithium battery according to one or more embodiments are illustrated. Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 Shows pouch type or similar battery. Figures 2 to 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 in which a separator 30 is provided between a positive electrode 10 and a negative electrode 20, and may further include a case 50 in which the electrode assembly 40 is housed. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in an electrolyte (not shown). Figure 2 As illustrated, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. In some embodiments, as shown in FIG. Figure 3As illustrated, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include an electrode tab 70 , or a positive electrode tab 71 and a negative electrode tab 72 serving as an electrical path to guide current generated in the electrode assembly 40 outward.

[0092] The following description will focus on an electrolyte for a rechargeable lithium battery according to some embodiments of the present disclosure.

[0093] The electrolyte for a rechargeable lithium battery according to the present embodiment may include a non-aqueous organic solvent, a lithium salt, and a first additive including a compound represented by Chemical Formula 1 (eg, represented by ).

[0094] Chemical formula 1

[0095]

[0096] In Chemical Formula 1, n may be an integer of 5 to 10.

[0097] In Chemical Formula 1, R may be a substituted or unsubstituted branched C3-C15 alkyl group. That is, the number of carbon atoms in R may be 3 to 15. For example, the number of carbon atoms in R (i.e., a substituted or unsubstituted branched C3-C15 alkyl group) may range from about 3 to about 15, about 3 to about 10, or about 5 to about 8. In other words, R may be a substituted or unsubstituted branched C3-C15 alkyl group, a substituted or unsubstituted branched C3-C10 alkyl group, or a substituted or unsubstituted branched C5-C8 alkyl group.

[0098] In Chemical Formula 1, R may be a branched alkyl group (i.e., a branched C3 to C15 alkyl group). For example, the branched alkyl group may be 1-methylethyl, 1-methylpropyl, 2-methylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, 1-propylbutyl, 2-propylbutyl, 3-propylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 4-ethylpentyl, 1-propylpentyl, 2-propylpentyl, 3-propylpentyl, 4- Propylpentyl, 1-butylpentyl, 2-butylpentyl, 3-butylpentyl, 4-butylpentyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 5-ethylhexyl, 1-propylhexyl, 2-propylhexyl, 3-propylhexyl, 4-propylhexyl, 5-propylhexyl, 1-butylhexyl, 2-butylhexyl, 3-butylhexyl, 4-butylhexyl or 5-butylhexyl.

[0099] In one or more embodiments of the present disclosure, in the compound represented by (eg, shown in) Chemical Formula 1, R may be a 1-ethylpentyl group. For example, the electrolyte may include a compound represented by (eg, shown in) Chemical Formula 1-1.

[0100] Chemical formula 1-1

[0101]

[0102] The first additive including the compound represented by Chemical Formula 1 (e.g., presented) can be used as a surfactant in the electrolyte to improve the impregnation of the electrolyte. For example, R of the compound represented by Chemical Formula 1 (e.g., presented) may have a branched structure, and thus the impregnation of the electrolyte can be further improved. Therefore, the amount of electrolyte present on the surface without being impregnated into the high-density (e.g., high-mixing density) negative electrode can be significantly reduced. In short, the thickness of the rechargeable lithium battery including the electrolyte can be reduced to increase the energy density (e.g., the energy density of the rechargeable lithium battery). In some embodiments, the increased impregnation can cause a film to be formed uniformly (e.g., substantially uniformly) between the negative electrode and the electrolyte, and thus the life characteristics can be improved.

[0103] The electrolyte for a rechargeable lithium battery according to the present embodiment may include a compound represented by (e.g., shown in) Chemical Formula 1, and may further include: a second additive that may be or include at least one selected from vinylene carbonate (VC), fluoroethylene carbonate (FEC), difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate (VEC), adiponitrile (AN), succinonitrile (SN), 1,3,6-hexanetricyano (HTCN), propene sultone (PST), propane sultone (PS), lithium tetrafluoroborate (LiBF4), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalato)phosphate (LiDFBOP), lithium difluoro(oxalato)borate (LiDFOB), and 2-fluorobiphenyl (2-FBP).

[0104] In one or more embodiments, the second additive (i.e., the electrolyte for a rechargeable lithium battery) may include one or both (e.g., simultaneously) of fluoroethylene carbonate (FEC) and vinylethylene carbonate (VEC). In one or more embodiments, the amount of the second additive may be from about 1 wt% to about 20 wt%, or from about 5 wt% to about 12 wt%, relative to the total weight of the electrolyte (100 wt%).

[0105] In one or more embodiments, the second additive may include fluoroethylene carbonate (FEC), vinyl ethylene carbonate (VEC), and lithium tetrafluoroborate (LiBF4). For example, relative to the total weight of the electrolyte, the amount of fluoroethylene carbonate (FEC) may be about 6 wt% to about 8 wt%, the amount of vinyl ethylene carbonate (VEC) may be about 0.5 wt% to about 2 wt%, and the amount of lithium tetrafluoroborate (LiBF4) may be about 0.05 wt% to about 1 wt%.

[0106] In one or more embodiments, the second additive (i.e., the electrolyte for a rechargeable lithium battery) may further include lithium difluoro(oxalato)borate (LiDFOB). For example, the amount of lithium difluoro(oxalato)borate (LiDFOB) included may be about 1 wt% to about 5 wt% relative to the total weight of the electrolyte.

[0107] In one or more embodiments, the lithium salt may include LiPF 6 .

[0108] 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 lithium salt may have a concentration equal to or greater than about 0.5 M or about 1.0 M. The lithium salt may have a concentration equal to or less than about 2.0 M, equal to or less than about 1.7 M, or equal to or less than about 1.5 M.

[0109] In another embodiment, a rechargeable lithium battery may be provided that includes: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte as described herein.

[0110] In one or more embodiments, the positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate compound, and cobalt-free nickel manganese oxide. For example, the positive electrode active material may include lithium cobalt oxide.

[0111] In one or more embodiments, the negative electrode active material may include at least one selected from the group consisting of a carbon-based negative electrode active material, a Si-based negative electrode active material, and a Sn-based negative electrode active material.

[0112] In one or more embodiments, the negative electrode may have a mixed density equal to or greater than about 1.7 grams per cubic centimeter (g / cc). For example, the negative electrode may have a mixed density ranging from about 1.7 g / cc to about 3.0 g / cc or from about 1.7 g / cc to about 2.5 g / cc.

[0113] In this description, the term "mixed density" can be obtained by dividing the weight of the components of the negative electrode (e.g., active material, binder, conductive material, etc.) other than the current collector (e.g., from the negative electrode) by the volume of the components of the negative electrode (e.g., active material, binder, conductive material, etc.) other than the current collector (e.g., from the negative electrode). For example, the mixed density of the negative electrode may refer to the density of the negative electrode active material layer AML2.

[0114] The electrolyte according to the present disclosure may have excellent impregnation properties and, therefore, may be easily impregnated into a high-density negative electrode having a mixed density equal to or greater than about 1.7 g / cc. Thus, a rechargeable lithium battery including the electrolyte of the present disclosure may have increased energy density and excellent or suitable life characteristics. In some embodiments, a rechargeable lithium battery including the electrolyte of the present disclosure may have reduced internal resistance and increased ionic conductivity.

[0115] The rechargeable lithium battery according to one or more embodiments of the present disclosure may be applied to automotive vehicles, mobile phones, and / or any other electronic devices (eg, laptop computers), but the present disclosure is not limited thereto.

[0116] Terms such as "substantially," "about," and "approximately" are used as relative terms, not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. They may include the stated value as well as an acceptable range of deviation determined by one of ordinary skill in the art to take into account the limitations and errors associated with the measurement of that quantity. For example, "about" may refer to one or more standard deviations, or ±30%, ±20%, ±10%, or ±5% of the stated value.

[0117] The numerical ranges disclosed herein include and are intended to disclose all subranges falling within the same numerical precision. For example, the range of "1.0 to 10.0" includes 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). Applicants therefore reserve the right to amend this specification (including the claims) to explicitly set forth any subranges falling within the ranges explicitly set forth herein.

[0118] The following will describe example embodiments and comparative examples of the present disclosure. However, the example embodiments described below are merely one or more possible examples, and the present disclosure is not limited to the example embodiments discussed herein.

[0119] Example embodiments and comparative examples

[0120] Example Implementation 1

[0121] (1) Preparation of electrolyte

[0122] 1.3 M LiPF6 was dissolved in a non-aqueous organic solvent including ethylene carbonate (EC), propylene carbonate (PC), ethyl propionate (EP), and propyl propionate (PP) mixed in a volume ratio of about 10:15:30:45, and then a first additive and a second additive were added to prepare an electrolyte.

[0123] Based on the total weight of the electrolyte, 7 wt % of fluoroethylene carbonate (FEC), 1 wt % of vinylethylene carbonate (VEC), and 0.2 wt % of LiBF 4 were added as a second additive.

[0124] The compound represented by Chemical Formula 1-1 (eg, presented) was added as a first additive in an amount of 1 wt % based on the total weight of the electrolyte.

[0125] Chemical formula 1-1

[0126]

[0127] (2) Manufacturing of rechargeable lithium batteries

[0128] LiNiCoAlO 2 as a positive electrode active material, polyvinylidene fluoride as a binder, and acetylene black as a conductive material were mixed at a weight ratio of 96:3:1, and the mixture was distributed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0129] The positive electrode active material slurry was coated on an Al foil having a thickness of 15 micrometers (μm), dried at 100° C., and then pressed to manufacture a positive electrode.

[0130] A silicon negative electrode active material, a styrene-butadiene rubber binder, and carboxymethyl cellulose were mixed in a weight ratio of 98:1:1, and the mixture was dispersed in distilled water to prepare a negative electrode active material slurry.

[0131] The negative electrode active material slurry was coated on a Cu foil having a thickness of 10 μm, dried at 100° C., and then pressed to produce a negative electrode having a mixed density of 1.7 grams per cubic centimeter (g / cc).

[0132] The positive electrode, the negative electrode, and a polyethylene separator having a thickness of 10 μm were assembled to prepare an electrode assembly, and an electrolyte was introduced to manufacture a rechargeable lithium battery.

[0133] Example Implementation 2

[0134] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Example Embodiment 1, except that the compound represented by Chemical Formula 1-1 (eg, represented by) was added in an amount of 2 wt %.

[0135] Example Implementation 3

[0136] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Example Embodiment 1, except that the compound represented by Chemical Formula 1-1 (eg, represented by) was added in an amount of 3 wt %.

[0137] Example Implementation 4

[0138] An electrolyte and a rechargeable lithium battery were manufactured by the same method as in Example Embodiment 3, except that lithium difluoro(oxalato)borate (LiDFOB) was further added as a second additive in an amount of 1 wt % relative to the total weight of the electrolyte.

[0139] Comparative Example 1

[0140] The electrolyte and the rechargeable lithium battery are prepared by the same method as Example Embodiment 1, except that the compound represented by (eg, presented in) Chemical Formula 1-1 is not added as the first additive if (eg, when) the electrolyte is prepared.

[0141] Comparative Example 2

[0142] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Example 1, except that a compound represented by Chemical Formula 2 (e.g., as shown) was added as a first additive in an amount of 1 wt % relative to the total weight of the electrolyte instead of the compound represented by Chemical Formula 1-1 (e.g., as shown).

[0143] Chemical formula 2

[0144]

[0145] Comparative Example 3

[0146] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Example 1, except that a compound represented by Chemical Formula 3 (e.g., as shown) was added as a first additive in an amount of 1 wt % relative to the total weight of the electrolyte instead of the compound represented by Chemical Formula 1-1 (e.g., as shown).

[0147] Chemical formula 3

[0148]

[0149] Evaluation Example 1: Electrolyte impregnation test

[0150] The electrolytes prepared according to Example Embodiments 1 to 4 and Comparative Examples 1 to 3 were dropped in an amount of 0.002 milliliters (mL) onto the surface of the negative electrode manufactured according to Example Embodiment 1, and then the area of ​​the electrolyte on the surface of the negative electrode was photographed 1 minute after the time of the dropping, and the degree of impregnation was evaluated based on the photographed image. The photographed image and the degree of impregnation were respectively Figure 6 and shown in Table 1.

[0151] The degree of impregnation was evaluated based on the spread area of ​​the electrolyte on the negative electrode. 1: The diameter of the electrolyte droplet is less than 1.0 millimeter (mm), 2: The diameter of the electrolyte droplet is greater than or equal to 1.0 mm and less than 1.5 mm, 3: The diameter of the electrolyte droplet is greater than or equal to 1.5 mm and less than 2.0 mm, 4: The diameter of the electrolyte droplet is greater than or equal to 2.0 mm and less than 2.5 mm, and 5: The diameter of the electrolyte droplet is greater than or equal to 2.5 mm and less than 3.0 mm.

[0152] Table 1

[0153] category Impregnation Comparative Example 1 1 Comparative Example 2 1 Comparative Example 3 1 Example Implementation 1 2 Example Implementation 2 3 Example Implementation 3 5 Example Implementation 4 5

[0154] refer to Figure 6, the captured images (a), (b), and (c) respectively show the regions of the electrolytes of Comparative Examples 1, 2, and 3, and the captured images (d), (e), (f), and (g) respectively show the regions of the electrolytes of Example Embodiments 1, 2, 3, and 4. From the captured images, it can be confirmed that each of the electrolytes of Example Embodiments 1 to 4 has significantly better impregnation than each of the electrolytes of Comparative Examples 1 to 3. For example, it can be confirmed that if (for example, when) an electrolyte including a compound represented by (for example, represented by) Chemical Formula 1 (for example, Chemical Formula 1-1) as the first additive is used, the impregnation into the negative electrode is significantly improved.

[0155] In some embodiments, it can be determined that if (e.g., when) lithium difluoro(oxalato)borate (LiDFOB) is further added as a second additive to the electrolyte including the compound represented (e.g., presented) by Chemical Formula 1 (e.g., Chemical Formula 1-1) (see Example Embodiment 4), the impregnation property is significantly improved.

[0156] Assessment 2: Thickness of Rechargeable Lithium Batteries

[0157] The thickness of the rechargeable lithium batteries (battery cells) prepared according to Comparative Examples 1 to 3 and Example Embodiments 1 to 4 was measured, and the results were Figure 7 Seven battery cells were prepared in each of the example embodiment and the comparative example, and the average thickness of the seven battery cells in each of the example embodiment and the comparative example is listed in Table 2.

[0158] Table 2

[0159] category Average battery cell thickness (mm) Comparative Example 1 4.783 Comparative Example 2 4.784 Comparative Example 3 4.784 Example Implementation 1 4.770 Example Implementation 2 4.756 Example Implementation 3 4.750 Example Implementation 4 4.732

[0160] refer to Figure 2 and Figure 7 , it can be determined that, due to the addition of the compound represented by (e.g., presented as) Chemical Formula 1 (e.g., Chemical Formula 1-1) as the first additive to the electrolyte, impregnation is improved and the thickness of the manufactured rechargeable lithium battery is reduced (see Tables 2 and Figure 7 (Comparative Examples 1 to 3 and Example Embodiments 1 to 4).

[0161] In particular, it can be determined that the thickness of the rechargeable lithium batteries of Example Embodiments 1 to 4, each of which includes a first additive (i.e., a compound having a branched alkyl group represented by Chemical Formula 1-1 (e.g., presented)), is significantly smaller than that of the rechargeable lithium battery of Comparative Example 1 which does not include the compound represented by Chemical Formula 1-1 (e.g., presented) as the first additive, and the rechargeable lithium batteries of Comparative Example 2 and Comparative Example 3 which respectively include a compound represented by Chemical Formula 2 or Chemical Formula 3 (e.g., presented) in which a straight-chain alkyl group is present as the first additive.

[0162] In summary, it can be determined that the electrolyte including the compound represented (e.g., presented) by Chemical Formula 1 (e.g., Chemical Formula 1-1) as the first additive has excellent impregnation properties to be uniformly (e.g., substantially uniformly) incorporated into the negative electrode, and thus the thickness of the manufactured battery cell is reduced to increase the energy density (e.g., of a rechargeable lithium battery).

[0163] The electrolyte for a rechargeable lithium battery according to one or more embodiments of the present disclosure may include a compound represented by (eg, presented as) Chemical Formula 1 (eg, Chemical Formula 1-1) as a first additive, thereby having excellent or appropriate impregnation properties.

[0164] A rechargeable lithium battery according to one or more embodiments of the present disclosure may include an electrolyte and thus may have excellent energy density and lifespan characteristics.

[0165] The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present disclosure described herein may be implemented using any appropriate hardware, firmware (e.g., an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the components of the device may be formed on an integrated circuit (IC) chip or on separate IC chips. Further, the components of the device may be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on a substrate. Further, the components of the device may 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 to perform the functions described herein. The computer program instructions are stored in a memory, which may be implemented in the computing device using a standard memory device (such as, for example, a random access memory (RAM)). The computer program instructions may also be stored in other non-transitory computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). Furthermore, those skilled in the art will recognize that, without departing from the scope of the present disclosure, the functions of the computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed across one or more other computing devices.

[0166] Although the present disclosure has been described in conjunction with what are presently considered to be example embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments and is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents, and the foregoing embodiments should therefore be understood as examples and not limiting the present disclosure in any way.

Claims

1. An electrolyte comprising: Non-aqueous organic solvents; lithium salts; and The first additive includes a compound represented by Chemical Formula 1, Chemical formula 1 In Chemical Formula 1, R is a substituted or unsubstituted branched C3-C15 alkyl group, and n is an integer from 5 to 10, The electrolyte is used in rechargeable lithium batteries. 2 . The electrolyte according to claim 1 , wherein the substituted or unsubstituted branched C 3 to C 15 alkyl group has 3 to 10 carbon atoms.

3. The electrolyte of claim 1 , wherein R is any one selected from the group consisting of 1-methylethyl, 1-methylpropyl, 2-methylpropyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, 1-propylbutyl, 2-propylbutyl, 3-propylbutyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 4-ethylpentyl, 1-propylpentyl, 2-propylpentyl , 3-propylpentyl, 4-propylpentyl, 1-butylpentyl, 2-butylpentyl, 3-butylpentyl, 4-butylpentyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1-ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 5-ethylhexyl, 1-propylhexyl, 2-propylhexyl, 3-propylhexyl, 4-propylhexyl, 5-propylhexyl, 1-butylhexyl, 2-butylhexyl, 3-butylhexyl, 4-butylhexyl and 5-butylhexyl. 4 . The electrolyte according to claim 1 , wherein the amount of the compound represented by Chemical Formula 1 is 1 wt % to 5 wt % relative to the total weight of the electrolyte.

5. The electrolyte of claim 1 , wherein the non-aqueous organic solvent comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylethyl carbonate, butylene carbonate, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, and caprolactone. 6 . The electrolyte according to claim 1 , wherein the nonaqueous organic solvent comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, ethyl propionate, and propyl propionate.

7. The electrolyte of claim 1, wherein the concentration of the lithium salt is 0.1 M to 2.0 M.

8. The electrolyte of claim 1 , further comprising a second additive, the second additive comprising at least one selected from the group consisting of vinylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, vinylethylene carbonate, adiponitrile, succinonitrile, 1,3,6-hexanetricyanide, propene sultone, propane sultone, lithium tetrafluoroborate, lithium difluorophosphate, lithium difluorobis(oxalato)phosphate, lithium difluoro(oxalato)borate, and 2-fluorobiphenyl. 9 . The electrolyte according to claim 8 , wherein the amount of the second additive is 1 wt % to 20 wt % relative to the total weight of the electrolyte.

10. The electrolyte of claim 8, wherein the second additive comprises at least one selected from the group consisting of fluoroethylene carbonate, vinylethylene carbonate, lithium tetrafluoroborate, and lithium difluoro(oxalato)borate.

11. The electrolyte of claim 8, wherein the second additive comprises fluoroethylene carbonate, vinylethylene carbonate, and lithium tetrafluoroborate.

12. The electrolyte according to claim 11, wherein Relative to the total weight of the electrolyte, the amount of fluoroethylene carbonate is 6 wt % to 8 wt %, the amount of vinylethylene carbonate is 0.5 wt % to 2 wt %, and the amount of lithium tetrafluoroborate is 0.05 wt % to 1 wt %.

13. The electrolyte of claim 11, wherein the second additive further comprises lithium difluoro(oxalato)borate.

14. The electrolyte according to claim 13, wherein the amount of lithium difluoro(oxalato)borate is 1 wt% to 5 wt% relative to the total weight of the electrolyte.

15. The electrolyte of claim 1, wherein the lithium salt comprises a salt selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiN(SO2C2F5)2, Li(CF3SO2)2N, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide, LiC4F9SO3, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), LiCl, LiI, LiB(C2O4)2, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate and lithium difluorobis(oxalato)phosphate, wherein x and y are each independently a natural number between 1 and 20. 16 . The electrolyte of claim 1 , wherein the nonaqueous organic solvent comprises ethylene carbonate, propylene carbonate, ethyl propionate, and propyl propionate in a volume ratio of 10:15:30:

45.

17. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and The electrolyte according to any one of claims 1 to 16.

18. The rechargeable lithium battery of claim 17, wherein the positive electrode active material comprises lithium cobalt-based oxide, lithium nickel-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel manganese-based oxide, or any combination thereof. 19 . The rechargeable lithium battery of claim 17 , wherein the negative electrode active material comprises at least one selected from the group consisting of a carbon-based negative electrode active material, a Si-based negative electrode active material, and a Sn-based negative electrode active material.

20. The rechargeable lithium battery of claim 17, wherein the negative electrode has a mixed density equal to or greater than 1.7 grams per cubic centimeter.

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