Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The present application provides an electrolyte including a non-aqueous organic solvent, a lithium salt, a first additive, and a second additive, and a rechargeable lithium battery including the electrolyte. A first additive of the electrolyte solution is represented by Chemical Formula 1, and a second additive is represented by Chemical Formula 2. Chemical formula 1 # imgabs0 # and chemical formula 2 # imgabs1 #

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0033841, filed on March 11, 2024, in the Korean Intellectual Property Office, the entire contents of which are hereby incorporated 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 rapidly increased. Therefore, intensive research has been conducted to improve the performance of rechargeable lithium batteries.

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode and the negative electrode include an active material capable of intercalating and deintercalating (e.g., lithium ions). For example, if (e.g., when) lithium ions are intercalated and / or deintercalated, the rechargeable lithium battery generates electrical energy caused by oxidation and reduction reactions.

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

[0007] One or more aspects relate to an electrolyte for a rechargeable lithium battery having improved stability and lifespan characteristics at high voltage.

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

[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 may include: a non-aqueous organic solvent; a lithium salt; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2.

[0011]

[0012] In Chemical Formula 2,

[0013] L 1 and L 2 may each independently be a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group,

[0014] A and B may each independently be a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group, and

[0015] At least one selected from A and B may be a group represented by Chemical Formula A.

[0016]

[0017] In chemical formula A, R 1 and R 2 Each independently may be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl. * may be a connection point with Chemical Formula 2.

[0018] According to one or more embodiments of the present disclosure, an electrolyte for a rechargeable lithium battery may include: a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2. A content (e.g., by weight) ratio of the second additive represented by Chemical Formula 2 to the first additive represented by Chemical Formula 1 may be in a range of about 1 to about 5.

[0019] According to one or more embodiments of the present disclosure, a rechargeable lithium battery may include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte. The electrolyte may include: a non-aqueous organic solvent; a lithium salt; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0021] Figure 2 、 Figure 4 and Figure 5 illustrates simplified conceptual diagrams each showing a rechargeable lithium battery according to one or more embodiments of the present disclosure, and Figure 3 A simplified cross-sectional view showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated. DETAILED DESCRIPTION

[0022] 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 accompanying drawings. However, it should be noted that the present disclosure is not limited to the following 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 enable those skilled in the art to fully understand the scope of the present disclosure.

[0023] 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 an intervening element may be present therebetween. In the drawings, the thickness of some components is exaggerated for efficient explanation of the technical content. The same reference numerals refer to the same elements throughout, and their repeated descriptions are not provided in the specification.

[0024] 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".

[0025] As used in this description, the terms "comprises / includes," "comprising / including," "comprise / include," "having," "has," and / or "have" are intended to specify the presence of specified components, features, numbers, steps (e.g., actions or tasks), elements, and / or (e.g., any appropriate) combinations thereof. However, the use of these terms does not prevent or exclude the possibility of the presence or addition of one or more other components, features, numbers, steps (e.g., actions or tasks), elements, and / or (e.g., any appropriate) combinations thereof.

[0026] As used herein, the term "combination thereof" may refer to a mixture, stack, composite, copolymer, alloy, blend, or reaction product of the components.

[0027] In one or more embodiments, the term "layer" herein includes not only a shape formed or provided on the entire surface but also a shape formed or provided on a partial surface if (for example, when) viewed from a plan view.

[0028] 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.

[0029] As used 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 without modifying the individual elements of the list. For example, "at least one of a-c" and "at least one of 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.

[0030] 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 in addition to the orientations illustrated in the drawings, the spatially relative terms are intended to encompass different orientations of the device in use or operation. 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.

[0031] 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 field and the meaning in the present disclosure, and will not be interpreted in an ideal or overly formal sense.

[0032] 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.

[0033] 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.

[0034] In this context, "consisting essentially of" means that any additional components will not materially affect the chemical, physical, optical, or electrical properties of the target moiety.

[0035] 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.

[0036] Rechargeable lithium battery

[0037] 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.

[0038] The positive electrode 10 and the negative electrode 20 may be spaced and / or separated from each other (e.g., spaced apart or separated) across the 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.

[0039] 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.

[0040] Positive electrode 10

[0041] 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 further include a binder and / or a conductive material.

[0042] For example, the positive electrode 10 may further include a component that may serve as a sacrificial positive electrode.

[0043] The positive electrode active material may include an amount of about 90 wt % to about 99 wt % based on 100 wt % of the positive electrode active material layer AML1, and an amount of the binder and the conductive material may each include an amount of about 0.5 wt % to about 5 wt % based on 100 wt % of the positive electrode active material layer AML1.

[0044] 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, acrylonitrile rubber, 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.

[0045] Conductive materials 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. Conductive materials may include, for example, carbon materials such as 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; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0046] An aluminum (Al) foil may be used as the positive electrode current collector COL1 , but the present disclosure is not limited thereto.

[0047] Positive electrode active material

[0048] The positive electrode active material in the positive electrode active material layer AML1 may include a compound that can reversibly intercalate and deintercalate 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, and combinations thereof.

[0049] The composite oxide may be or include a lithium transition metal composite oxide, such as a lithium nickel oxide, a lithium cobalt oxide, a lithium manganese oxide, a lithium iron phosphate compound, a cobalt-free nickel manganese oxide, or a combination thereof.

[0050] For example, the positive electrode active material may include a compound represented by one selected from the following chemical formulas: Li 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 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 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 Lia FePO4(0.90≤a≤1.8).

[0051] 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.

[0052] For example, based on 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.

[0053] Negative electrode 20

[0054] 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.

[0055] For example, the negative electrode active material layer AML2 may 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 100 wt % of the negative electrode active material layer AML2.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 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, or Li.

[0060] The dry binder may include a fibrillable polymeric material, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0061] Conductive materials 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 may include carbon materials such as 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; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0062] The negative electrode current collector COL2 may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

[0063] Negative electrode active material

[0064] The negative electrode active material in the negative electrode active material layer AML2 may include a material that can reversibly intercalate and deintercalate lithium ions, lithium metal, a lithium metal alloy, a material that can dope and dedope lithium, or a transition metal oxide.

[0065] The material that can reversibly intercalate and deintercalate lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. For example, the crystalline carbon may include graphite, such as amorphous, flaky, flaky, spherical, or fibrous natural or artificial graphite, and the amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbon, or calcined coke.

[0066] The lithium metal alloy may 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.

[0067] The material capable of doping and undoping lithium may include a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is 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, or a combination thereof), or a combination thereof. The Sn-based negative electrode active material may include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), a Sn-based alloy, or a combination thereof.

[0068] 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 the primary silicon particles, and for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0069] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles, and may also include an amorphous carbon coating located on the surface of the core.

[0070] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material.

[0071] Separator 30

[0072] Based on the type or kind 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 its multi-layer separator (such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene triple-layer separator, and a polypropylene / polyethylene / polypropylene triple-layer separator).

[0073] The separator 30 may include a porous substrate and a coating located on one or opposite surfaces of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0074] 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 materials mentioned herein.

[0075] The organic material may include a polyvinylidene fluoride-based copolymer or a (meth)acrylic acid-based copolymer.

[0076] 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.

[0077] 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.

[0078] Electrolyte ELL

[0079] The electrolyte ELL for a rechargeable lithium battery may include a non-aqueous organic solvent and a lithium salt.

[0080] The non-aqueous organic solvent may serve as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0081] 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.

[0082] The carbonate-based solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), or butylene carbonate (BC).

[0083] The ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, or caprolactone.

[0084] Ether solvents may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, or tetrahydrofuran. Alcohol solvents may include ethanol or propanol. Ketone solvents may include cyclohexanone. Aprotic solvents may include nitriles, such as R-CN (wherein R is a hydrocarbon group having a C2-C20 linear, branched, or cyclic structure, and may include a double bond, an aromatic ring, or an ether group); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane or 1,4-dioxolane); or sulfolane.

[0085] The nonaqueous organic solvent may be used alone or as a mixture of two or more species.

[0086] 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.

[0087] The lithium salt may be a material dissolved in a non-aqueous organic solvent, used as a supply source of lithium ions 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. The lithium salt may include, for example, 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) (x and y are integers between 1 and 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFBOP) and lithium bis(oxalato)borate (LiBOB).

[0088] Rechargeable lithium battery

[0089] Based on the shape of the rechargeable lithium battery, the rechargeable lithium battery can be classified into cylindrical batteries, prismatic batteries, pouch-type or similar batteries, and coin-type or similar batteries. Figure 2 、 Figure 4 and Figure 5 and illustrates a simplified cross-sectional view of a rechargeable lithium battery according to one or more embodiments. Figure 3 middle, Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 Shows a 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 3 As 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 As shown, the rechargeable lithium battery 100 may include a positive electrode tab 71 and a negative electrode tab 72, which serve as an electrical path for guiding the current generated in the electrode assembly 40 outward. Figure 5 As shown, the rechargeable lithium battery 100 may include an electrode tab 70 serving as an electrical path for guiding current generated in the electrode assembly 40 outward.

[0090] Hereinafter, an electrolyte for a rechargeable lithium battery according to some embodiments of the present disclosure will be described in more detail.

[0091] An electrolyte for a rechargeable lithium battery according to one or more embodiments may include a non-aqueous organic solvent, a lithium salt, a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2.

[0092] The electrolyte can be prepared by a mixing process, wherein the lithium salt is dissolved in a non-aqueous organic solvent, and the first additive and the second additive are added to mix. The electrolyte mixing process is well known in the field of electrolyte manufacturing, and those skilled in the art will be able to select and use it appropriately or properly.

[0093] The non-aqueous organic solvent may include at least one selected from ethylene carbonate (EC), propylene carbonate (PC), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) and butylene carbonate (BC).

[0094] In one or more embodiments, the non-aqueous organic solvent may be a mixed (eg, mixture) solvent of ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP).

[0095] For example, the content of ethylene carbonate (EC) may be about 5 vol% to about 20 vol% relative to 100 vol% of the total volume of the non-aqueous organic solvent. The content of propylene carbonate (PC) may be about 10 vol% to about 30 vol% relative to 100 vol% of the total volume of the non-aqueous organic solvent. The content of propyl propionate (PP) may be about 50 vol% to about 80 vol% relative to 100 vol% of the total volume of the non-aqueous organic solvent.

[0096] In one or more embodiments, the lithium salt may include LiPF 6 .

[0097] 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 equal to or greater than 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. In the present disclosure, if (for example, when) the lithium salt has a concentration of about 0.1 M to about 2.0 M, the electrolyte may suitably or appropriately maintain its conductivity and viscosity.

[0098] The first additive according to one or more embodiments of the present disclosure may be lithium difluoro(oxalato)borate represented by Chemical Formula 1, or LiDFOB.

[0099]

[0100] Since the first additive has a halogen component such as fluorine, LiF generated during the charge-discharge process can form a strong film on the positive electrode and the negative electrode. Therefore, the first additive can effectively contribute to the life characteristics of the lithium battery.

[0101] The content of the first additive may be about 0.5 wt % to about 3 wt % relative to 100 wt % of the total weight of the electrolyte. For example, the content of the first additive may be about 1 wt % to about 2 wt % relative to 100 wt % of the total weight of the electrolyte. If (for example, when) the content of the first additive is less than the disclosed range (time), there will be a problem of not being able to sufficiently provide a film on the positive electrode and the negative electrode, and if (for example, when) the content of the first additive is greater than the disclosed range (time), there will be a problem of reduced battery capacity and life due to increased resistance of the positive electrode and the negative electrode.

[0102] The second additive according to one or more embodiments of the present disclosure may be represented by Chemical Formula 2.

[0103]

[0104] In Chemical Formula 2,

[0105] L 1 and L2 Each may independently be a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group.

[0106] A and B may each independently be a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0107] At least one selected from A and B may be a group represented by Chemical Formula A.

[0108]

[0109] In chemical formula A,

[0110] R 1 and R 2 Each of them may be independently hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl. The alkyl group may include a linear alkyl group and / or a chain alkyl group, and the cycloalkyl group may include a cyclic alkyl group.

[0111] For example, selected from L 1 and L 2 At least one of them may be a substituted or unsubstituted C1-C5 alkylene group.

[0112] For example, L 1 and L 2 Each independently may be a substituted or unsubstituted C1-C5 alkylene group.

[0113] For example, selected from L 1 and L 2 At least one of them may be a substituted or unsubstituted C2-C5 alkylene group.

[0114] For example, L 1 and L 2 Each independently may be a substituted or unsubstituted C2-C5 alkylene group.

[0115] The sulfone group included in Chemical Formula 2 may form a film on the surface of the positive electrode to suppress or reduce decomposition of the positive electrode active material, thereby making it possible to suppress or reduce gas generation and dissolution of transition metals due to decomposition of the positive electrode active material.

[0116] The second additive represented by Chemical Formula 2 may strengthen a solid electrolyte interface (SEI) layer on the surface of the negative electrode while preventing or reducing degradation of the SEI layer or dissolution of transition metals from the positive electrode during high-temperature storage.

[0117] For example, Chemical Formula 2 can be represented by Chemical Formula 2-1.

[0118]

[0119] In Chemical Formula 2-1,

[0120] L 1 and L 2 Each independently may be a substituted or unsubstituted C2-C5 alkylene group.

[0121] R 1A 、R 1B 、R 2A and R 2B They may each independently be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

[0122] In one or more embodiments, the second additive may be selected from the compounds listed in Group 1.

[0123]

[0124] The content of the second additive may be about 0.5 wt % to about 5 wt % relative to 100 wt % of the total weight of the electrolyte. For example, the content of the second additive may be about 1 wt % to about 3 wt % relative to 100 wt % of the total weight of the electrolyte. If (for example, when) the content of the second additive is within the disclosed range, an increase in resistance at high temperatures can be prevented or reduced to achieve a rechargeable lithium battery with improved lifespan and output characteristics.

[0125] If (for example, when) the second additive is used in combination with a fluorinated lithium salt additive (for example, the first additive), a synergistic effect can be produced. The combination of the first additive and the second additive can suppress gas generation, increase high-temperature storage performance, and improve high-temperature cycling stability of the lithium battery.

[0126] For example, in the electrolyte according to the present disclosure, the effect of reducing HF generation due to salt stabilization caused by the first additive and the effect of triazole-based positive electrode metal coordination can occur simultaneously (e.g., synchronously) with each other, thereby inhibiting or reducing the dissolution of transition metals under high-temperature storage to effectively prevent or reduce positive electrode degradation.

[0127] In one or more embodiments of the present disclosure, the electrolyte for a rechargeable lithium battery may include a first additive represented by Chemical Formula 1 and a second additive represented by Chemical Formula 2, and a content ratio of the second additive to the first additive may range from about 1 to about 5. The electrolyte for a rechargeable lithium battery according to one or more embodiments may further include a nonaqueous organic solvent and a lithium salt.

[0128] In the electrolyte, the content of the second additive may be greater than that of the first additive. The content ratio of the second additive to the first additive may be in the range of about 1 to about 5. According to one or more embodiments, the content ratio of the second additive to the first additive may be in the range of about 1 to about 3.

[0129] If (for example, when) the content ratio of the second additive to the first additive is less than the disclosed range, the coulombic efficiency will be sharply reduced, and if (for example, when) the content ratio of the second additive to the first additive is greater than the disclosed range, a protective layer will not be sufficiently provided on the surface of the positive electrode.

[0130] In one or more embodiments of the present disclosure, a rechargeable lithium battery may include: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte, and the electrolyte may include a non-aqueous organic solvent, a lithium salt, a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2.

[0131] In a rechargeable lithium battery according to one or more embodiments of the present disclosure, the electrolyte may decompose during the initial charge-discharge period to form a film with passivation ability on the surface of the positive electrode and the negative electrode, thereby improving high-temperature storage characteristics. Due to the thermal decomposition of the lithium salts (LiPF6, etc.) of the widely used rechargeable lithium batteries, the acid (such as HF and PF5) produced can degrade the film. This acid corrosion causes the transition metal to dissolve from the positive electrode, and the surface resistance of the electrode increases due to structural changes on the surface. Therefore, the theoretical capacity caused by the loss of the metal element as the redox (reduction and oxidation) center is reduced, which leads to a reduction in capacity. In some embodiments, the dissolved transition metal ions can be electrodeposited on the negative electrode, which reacts in a strong reduction potential range. Therefore, during the electrodeposition period, electrons are consumed and the film is destroyed, and accordingly the surface of the negative electrode is exposed to cause additional electrolyte decomposition reactions. Therefore, there will be an increase in the surface resistance and irreversible capacity of the negative electrode, and as a result, there will be a problem of continuous reduction in the capacity of the battery cell.

[0132] In the present disclosure, the triazole group and the sulfone group of the second additive represented by Chemical Formula 2 may provide an unshared electron pair to capture PF5 and stabilize LiPF6 salt, and as a result, it may be possible to remove acid caused by decomposition of the lithium salt.

[0133] Rechargeable lithium batteries may be used in automobiles, mobile phones, and / or any other electrical devices, but the present disclosure is not limited thereto. Rechargeable lithium batteries may be suitable for charge rates or operation at high voltages. For example, the rechargeable lithium battery may have a maximum charge voltage equal to or greater than approximately 4.5V, approximately 4.5V to approximately 4.7V, approximately 4.5V to approximately 4.6V, or approximately 4.5V to approximately 4.55V.

[0134] The positive electrode active material of the rechargeable lithium battery may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium iron phosphate compounds, and cobalt-free nickel manganese oxides. For example, the positive electrode active material may include lithium cobalt oxides.

[0135] The negative electrode active material of the rechargeable lithium battery may include carbon-based negative electrode active materials, silicon-based negative electrode active materials, or any combination thereof.

[0136] The silicon-based negative electrode active material may include: a core including silicon-based particles and a coating including amorphous carbon. The silicon-based particles may include one or more of silicon particles, silicon-carbon composites, SiO x (0 < x ≤ 2) and silicon alloys.

[0137] Terms such as "substantially", "about", and "approximate" are used as relative terms and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art. They may include the recited value and deviations within an acceptable range determined by a person of ordinary skill in the art considering 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 recited value.

[0138] The numerical ranges disclosed herein include and are intended to disclose all sub-ranges that fall within the same numerical precision. For example, the range of "1.0 to 10.0" includes all sub-ranges (such as, for example, 2.4 to 7.6) having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0. The applicant therefore reserves the right to amend this specification (including the claims) to expressly recite any sub-range that falls within the ranges expressly recited herein.

[0139] Embodiments and comparative examples of the present disclosure will be described below. The following embodiments are merely one or more possible implementations of the present disclosure, and the present disclosure is not limited to the following embodiments.

[0140] Embodiments and Comparative Examples

[0141] Example 1

[0142] (1) Preparation of electrolyte

[0143] 1.3 M LiPF6 was dissolved in a non-aqueous organic solvent (where ethylene carbonate (EC), propylene carbonate (PC), and propyl propionate (PP) were mixed in a volume ratio of about 10:15:75), and 1 wt% of a first additive and 1 wt% of a second additive were added based on the total weight of 100 wt% of the electrolyte to prepare the electrolyte.

[0144] The material represented by Chemical Formula 1 is used as the first additive.

[0145]

[0146] The material represented by Chemical Formula 2a is used as the second additive.

[0147] For example, the second additive according to Chemical Formula 2a can be produced by the synthesis examples described herein.

[0148] Synthesis example

[0149] Divinyl sulfone (1.1 mmol) mixed with 3 milliliters (mL) of acetone was added dropwise to a solution of 1H-1,2,4-triazole (2 mmol) mixed in acetone over 30 minutes and stirred thoroughly with sodium bicarbonate (3 mmol). The mixture was then stirred at room temperature (25°C) for 4 hours, and the precipitate was filtered. The filtered solution was recrystallized to obtain the compound of Chemical Formula 2a.

[0150]

[0151] (2) Manufacturing of rechargeable lithium batteries

[0152] 97wt% of LiCoO2 (LCO), 0.5wt% of artificial graphite powder as a conductive material, 0.8wt% of carbon black (Ketjen black), 0.2wt% of acrylonitrile rubber, 1.5wt% of polyvinylidene fluoride (PVdF) were mixed and added to N-methyl-2-pyrrolidone, and then the mixture was stirred for 30 minutes by using a mechanical stirrer to produce a positive electrode active material slurry. A scraper was used to coat the slurry with a thickness of about 60 microns (μm) on an aluminum current collector with a thickness of about 20 μm, dried in a hot air dryer at 100°C for 0.5 hours, dried again at 120°C for 4 hours in a vacuum condition, and then rolled to produce a positive electrode.

[0153] The negative electrode active material in which 98wt% of artificial graphite and silicon-carbon composite were mixed in a volume ratio of 93:7, 1wt% of styrene-butadiene rubber (SBR) and 1wt% of carboxymethyl cellulose (CMC) were mixed and added to distilled water, and then stirred for 60 minutes using a mechanical stirrer to produce a negative electrode active material slurry. The slurry having a thickness of about 60μm was coated on a copper current collector having a thickness of about 10μm using a scraper, dried in a hot air dryer at 100°C for 0.5 hours, dried again at 120°C for 4 hours in a vacuum condition, and then rolled to produce a negative electrode.

[0154] The positive electrode, the negative electrode, and a polyethylene separator having a thickness of 10 μm were assembled to manufacture an electrode assembly, and an electrolyte was introduced to manufacture a rechargeable lithium battery.

[0155] Example 2

[0156] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that 2 wt % of the second additive was coated.

[0157] Example 3

[0158] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that 3 wt % of the second additive was coated.

[0159] Example 4

[0160] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that 2 wt % of the first additive was coated.

[0161] Example 5

[0162] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that the first additive was not added if (eg, when) preparing the electrolyte.

[0163] Comparative Example 1

[0164] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that no additive was added if (eg, when) preparing the electrolyte.

[0165] Comparative Example 2

[0166] An electrolyte and a rechargeable lithium battery were manufactured by substantially the same method as that of Example 1, except that the second additive was not added if (eg, when) preparing the electrolyte.

[0167] Evaluation Example

[0168] Rechargeable lithium batteries were evaluated by the methods described herein.

[0169] Evaluation 1: Charge and discharge characteristics at high temperatures

[0170] The rechargeable lithium batteries manufactured in Examples and Comparative Examples were charged and discharged for 200 cycles at 45° C. under the conditions of 2.0 C charge (CC / CV, 4.53 V cutoff) and 1.0 C discharge (CC, 3.0 V cutoff), and the high-temperature capacity retention rate was calculated and listed in Table 1. The high-temperature capacity retention rate was calculated according to Equation 1.

[0171] Equation 1

[0172] High temperature capacity retention rate (%) = (discharge capacity after 200 cycles / initial discharge capacity) × 100

[0173] Assessment 2: Resistance Test

[0174] The rechargeable lithium batteries according to Examples and Comparative Examples were charged to 4.53 V at 45° C., and their initial resistance values ​​and resistance values ​​after storage at 60° C. for 28 days were measured, and the resistance increase rates were calculated and listed in Table 1. The resistance values ​​were measured using electrochemical impedance spectroscopy (EIS).

[0175] The resistance increase rate was calculated according to Equation 2.

[0176] Equation 2

[0177] Resistance increase rate after high-temperature storage (%) = (resistance value after storage at 60°C for 28 days / initial resistance value) × 100 Evaluation 3: Gas generation at high temperature

[0178] The rechargeable lithium batteries according to the examples and comparative examples were evaluated for gas generation characteristics at high temperatures. The rechargeable lithium batteries according to the examples and comparative examples were charged to 4.53 V at 45° C. and then stored at 60° C. for 28 days.

[0179] In order to determine the gas reduction effect, the initial thickness of the battery cell and the thickness of the battery cell after storage at 60° C. for 28 days were each measured, and the thickness increase rate was calculated and listed in Table 1. The thickness increase rate was calculated according to Equation 3.

[0180] Equation 3

[0181] Thickness increase rate during life (%) = [(battery cell thickness after storage at 60°C for 28 days - battery cell initial thickness) / (battery cell initial thickness)] × 100

[0182] For example, a thickness gauge of a pressing type or type commercially available from Mitutoyo Corporation is used so that a pouch-shaped battery cell is positioned between pressing plates, and then the thickness of the battery cell is measured while being pressed with a weight of 300 grams (g). In Equation 3, the thickness measured immediately after release from an oven at 60°C is shown to exclude the cooling effect, and the same method is performed to measure the thickness after storage in a thermostat at 60°C for 28 days.

[0183] Evaluation 4: ICP-MS Analysis (Evaluation of Transition Metal Dissolution)

[0184] The rechargeable lithium batteries according to Examples and Comparative Examples were charged and discharged for 200 cycles under the conditions of 2.0 C charge (CC / CV, 4.53 V cutoff) and 1.0 C discharge (CC, 3.0 V cutoff) at 45° C., and then the dissolution amount of transition metal ions (e.g., cobalt (Co)) was measured using the method described herein.

[0185] The rechargeable lithium battery was disassembled to separate the positive electrode. The separated positive electrode and the electrolyte were placed in a 10 mL Teflon container and sealed, and the amount of cobalt (Co) was measured by ICP-MS analysis and listed in Table 1.

[0186] Table 1

[0187]

[0188] Comprehensive Assessment

[0189] Referring to Table 1, it can be determined that, compared to the case of using an electrolyte without additives (i.e., Comparative Example 1) and the case of using an electrolyte with only the first additive added (i.e., Comparative Example 2), in the case of Examples 1 to 4 using the electrolytes according to the present invention with the first and second additives added, the high temperature (60°C) storage property and the resistance increase rate are significantly improved. In some embodiments, it can be determined that, compared to Example 5 in which the second additive is used alone, in Examples 1 to 4 in which the first and second additives are combined, the high temperature (60°C) storage property and the resistance increase rate are significantly improved.

[0190] Therefore, if (eg, when) the electrolyte is added with a combination of the first additive and the second additive according to the present disclosure, it can be observed that the cycle properties and life efficiency of the battery are improved under a high temperature (60° C.) storage environment.

[0191] Referring again to Table 1, it can be found that the change in thickness of the battery cells of the rechargeable lithium batteries manufactured according to Comparative Examples 1 and 2 stored at high temperature (60°C) is greater than the change in thickness of the battery cells of the rechargeable lithium batteries manufactured according to Examples 1 to 5 stored at high temperature (60°C).

[0192] Furthermore, it was found that the rechargeable lithium batteries manufactured according to the examples had an appropriate or extremely low amount of Co leaching. In contrast, it was confirmed that the amount of Co leaching in the rechargeable lithium batteries manufactured according to the comparative examples was significantly greater than that in the rechargeable lithium batteries manufactured according to the examples. Accordingly, in the rechargeable lithium batteries according to the examples, the amount of gas generated can be significantly reduced as the cycle progresses.

[0193] As a result, in a rechargeable lithium battery using the additive represented by Chemical Formula 1 and the additive represented by Chemical Formula 2 according to the present disclosure, gas generation at high temperature (60° C.) may be effectively suppressed or reduced.

[0194] If (for example, when) the rechargeable battery is activated, the electrolyte according to one or more embodiments may exhibit effects of improving lifespan characteristics and stability under high voltage conditions.

[0195] The electrolyte according to one or more embodiments may provide a rechargeable lithium battery having improved lifespan characteristics at high temperatures, having an effect of suppressing an increase in battery resistance during high-temperature storage, and having an effect of suppressing gas generation.

[0196] The battery management system (BMS) device and / or any other related devices or components 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.

[0197] 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 example 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 therefore the foregoing embodiments should be understood as examples and not limiting the present disclosure in any way.

Claims

1. An electrolyte, comprising: Non-aqueous organic solvents; lithium salts; a first additive represented by Chemical Formula 1; and The second additive represented by Chemical Formula 2, Chemical formula 1 Chemical formula 2 Wherein, in Chemical Formula 2, L 1 and L 2 Each is independently a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group, A and B are each independently a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group, At least one selected from A and B is a group represented by chemical formula A, Chemical formula A Wherein, in chemical formula A, R 1 and R 2 are each independently hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl, and * is the connection point with Chemical Formula 2, and The electrolyte is used in rechargeable lithium batteries.

2. The electrolyte according to claim 1, wherein the 1 and L 2 At least one of them is a substituted or unsubstituted C1-C5 alkylene group.

3. The electrolyte according to claim 1, wherein the 1 and L 2 At least one of them is a substituted or unsubstituted C2-C5 alkylene group.

4. The electrolyte of claim 1, wherein L 1 and L 2 Each is independently a substituted or unsubstituted C2-C5 alkylene group.

5. The electrolyte of claim 1, wherein the second additive is represented by Chemical Formula 2-1, Chemical formula 2-1 and in, In Chemical Formula 2-1, L 1 and L 2 are each independently a substituted or unsubstituted C2-C5 alkylene group, and R 1A 、R 1B 、R 2A and R 2B Each is independently hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

6. The electrolyte according to claim 1, wherein the second additive is represented by any one selected from the compounds listed in Group 1, Group 1 7 . The electrolyte according to claim 1 , wherein the content of the first additive is 0.5 wt % to 3 wt % relative to 100 wt % of the total weight of the electrolyte. 8 . The electrolyte according to claim 1 , wherein the content of the second additive is 0.5 wt % to 5 wt % relative to 100 wt % of the total weight of the electrolyte. 9 . The electrolyte according to claim 1 , wherein the content ratio of the second additive to the first additive is 1 to 5.

10. The electrolyte according to claim 1, wherein the non-aqueous organic solvent comprises a carbonate solvent, The carbonate solvent includes at least one selected from the group consisting of ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, propylene carbonate and butylene carbonate.

11. The electrolyte according to claim 1, wherein the non-aqueous organic solvent comprises: A mixed solvent comprising ethylene carbonate, propylene carbonate and propyl propionate.

12. The electrolyte according to claim 11, wherein the content of ethylene carbonate is 5 vol% to 20 vol%, the content of propylene carbonate is 10 vol% to 30 vol%, and the content of propyl propionate is 50 vol% to 80 vol%, based on 100 vol% of the total volume of the non-aqueous organic solvent.

13. The electrolyte of claim 1, wherein the lithium salt comprises a salt selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide, LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate and lithium bis(oxalato)borate, wherein x and y are integers between 1 and 20. The electrolyte according to claim 1 , wherein the concentration of the lithium salt is 0.1 M to 2.0 M.

15. A rechargeable lithium battery comprising: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; and The electrolyte according to any one of claims 1 to 14.

16. The rechargeable lithium battery of claim 15, wherein the positive electrode active material comprises at least one selected from the group consisting of lithium cobalt-based oxides, lithium nickel-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, and cobalt-free nickel manganese-based oxides.

17. The rechargeable lithium battery of claim 15, wherein the positive electrode active material is at least one selected from the group consisting of: Li a A 1-b X b O 2-c D c , of which 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 , where 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 , where 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 c O 2-α D α , where 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, where 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, where 0.90≤a≤1.8, 0.001≤b≤0.1, Li a CoG b O2, where 0.90≤a≤1.8, 0.001≤b≤0.1, Li a Mn 1-b G b O2, where 0.90≤a≤1.8, 0.001≤b≤0.1, Li a Mn2G b O4, where 0.90≤a≤1.8, 0.001≤b≤0.1, Li a Mn 1-g G g PO4, where 0.90≤a≤1.8, 0≤g≤0.5, Li (3-f) Fe2(PO4)3, where 0≤f≤2, and Li a FePO4, where 0.90≤a≤1.8, A is Ni, Co, Mn or a combination thereof, X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof, D is O, F, S, P or a combination thereof, G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof, and L 1 Mn, Al or a combination thereof. 18 . The rechargeable lithium battery of claim 15 , wherein the negative electrode active material comprises a carbon-based negative electrode active material, a silicon-based negative electrode active material, or a combination thereof.

19. The rechargeable lithium battery of claim 15, wherein a maximum charging voltage of the rechargeable lithium battery is equal to or greater than 4.5V.

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