Rechargeable lithium battery and electrolyte therefor

Abstract

The invention relates to a rechargeable lithium battery and an electrolyte for the rechargeable lithium battery. There is provided a rechargeable lithium battery including a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte. An active mass density of the negative electrode is greater than or equal to about 1.7 g / cc, and the electrolyte solution includes a lithium salt, a non-aqueous organic solvent, a first additive represented by Chemical Formula 1, and a second additive represented by Chemical Formula 2. Chemical formula 1R1-O-R2 chemical formula 2 # imgabs0 #

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0098393 filed on July 27, 2023 in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field According to one or more embodiments, the present disclosure relates to a rechargeable lithium battery and an electrolyte for a rechargeable lithium battery. Background Art Recently, with the rapid popularization of electronic devices using rechargeable lithium batteries (such as mobile phones, laptop computers, electric vehicles, etc.), the demand for rechargeable batteries with relatively high energy density and relatively high capacity is rapidly increasing. Accordingly, research and development to improve the performance of rechargeable lithium batteries is being actively carried out. A rechargeable lithium battery includes a positive electrode and a negative electrode (including an active material capable of inserting and extracting lithium ions), and an electrolyte. If (eg, when) lithium ions are inserted / extracted from the positive electrode and the negative electrode, electrical energy is generated through oxidation and reduction reactions. One of the latest developments in technology for rechargeable lithium batteries is to increase the energy density of the negative electrode. However, if (e.g., when) the energy density of the negative electrode is increased, the void volume may decrease, and the amount of electrolyte impregnated into the negative electrode increases, which may result in an increase in battery thickness and a decrease in cycle life. Summary of the invention One or more aspects relate to a rechargeable lithium battery that increases the active mass density of a negative electrode and suppresses an increase in battery thickness and a decrease in battery cycle life. 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 embodiments presented in the disclosure. According to one or more embodiments, 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. The active mass density of the negative electrode may be greater than or equal to about 1.7 grams per cubic centimeter (g / cc), and the electrolyte may include a lithium salt; a non-aqueous organic solvent; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2: Chemical formula 1 R 1 -OR 2 Chemical formula 2 A rechargeable lithium battery according to one or more embodiments may increase the active mass density of a negative electrode while suppressing or reducing an increase in battery thickness and a decrease in cycle life. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 to Figure 4 is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments. Reference numerals 100: Rechargeable lithium battery 10: Positive electrode 11: Positive electrode lead tab 12: Positive terminal 20: Negative electrode 21: Negative electrode lead lug 22: Negative terminal 30: Separator 40: electrode assembly 50: shell 60: Sealing member 70: Electrode terminal piece 71: Positive electrode terminal tab 72: Negative electrode terminal tab DETAILED DESCRIPTION Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the attached drawings so that those of ordinary skill in the art can easily implement them. Examples of the present disclosure are illustrated in the attached drawings, in which the same reference numerals refer to the same elements throughout, and their repeated description may not be provided. Accordingly, embodiments are described with reference to the drawings to explain aspects of the present description. However, these embodiments are only examples, and the present disclosure is not limited thereto. On the contrary, the present disclosure is limited by the scope of the claims. In the drawings, the thickness of layers, films, panels, regions, etc. are exaggerated for clarity, wherein the same reference numerals denote the same elements, and repeated descriptions thereof may not be provided in the specification. As used herein, if (for example, when) a specific definition is provided in another manner, it will be understood that if (for example, when) an element (such as a layer, film, region, or substrate) is referred to as being "on" another element (such as a layer, film, region, or substrate), it may be directly on the other element (such as a layer, film, region, or substrate), or intervening elements may also be present. In one or more embodiments, the term “layer” herein includes not only a shape formed on the entire surface if (for example, when) viewed from a plan view but also a shape formed on a partial surface. 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 parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings described herein, the first element, component, region, layer or part described herein may be referred to as a second element, component, region, layer or part. As used herein, if (for example, when) no specific definition is otherwise provided, the singular may also include the plural. In one or more embodiments, "A or B" may mean "including A, including B, or including A and B", unless otherwise specified. As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of the components. In this document, it should be understood that terms such as “comprises,” “comprise,” “comprising,” “includes,” “including,” “include,” “having,” “has,” and / or “have” are intended to mark the existence of specified aspects, quantities, operations, elements, and / or any appropriate combination thereof, but do not exclude the possibility of the existence or addition of one or more other features, quantities, operations, elements, and / or any appropriate combination thereof. 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 and do not modify the individual elements of the list. For example, the expressions "at least one of a to 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), b and c (e.g., simultaneously), all of a, b, and c, or variations thereof. Spatially relative terms such as "below," "below," "below," "above," "on," etc. may be used herein to easily describe the relationship of one element or feature to 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 turned over, an element described as being "below" or "below" other elements or features will be oriented "above" the other elements or features. Thus, the example term "below" may (e.g., simultaneously) encompass both the orientations 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. The terms used in this article are only used for the purpose of describing a particular embodiment and are not intended to limit the present disclosure. Unless otherwise defined, all terms used in the present disclosure (including chemical, technical and scientific terms) are the same as those commonly 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 a meaning consistent with the meaning in the context of the relevant field and the present disclosure, and will not be interpreted in an ideal or overly formal sense. Example embodiments are described herein with reference to cross-sectional views of schematic diagrams as ideal embodiments. As such, variations in the shapes illustrated can be expected due to, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of the zones illustrated herein, but rather include deviations in shape, for example, caused by manufacturing. For example, a zone illustrated or described as flat may typically have rough and / or nonlinear features. Moreover, illustrated sharp angles may be rounded. Therefore, the zones illustrated in the accompanying drawings are schematic in nature, and their shapes are not intended to illustrate the precise shape of the zones, and are not intended to limit the scope of the claims. The term "may" will be understood to refer to "one or more embodiments of the present disclosure," some of which include the described elements and some of which do not include the elements 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 listed items. In this context, "consisting essentially of" means that any additional components do not significantly affect the chemical, physical, optical or electrical properties of the target moiety. 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. definition In the present disclosure, "does not include one or any 'component'", "excludes one or any 'component'", "does not contain 'component'", etc. means that the 'component' is not added, selected or used as a component in the composition / structure, but due to other impurities and / or external factors, less than an appropriate amount of the 'component' may still be included. The term "metal" is interpreted as a concept including common metals, transition metals and metalloids (semimetals). As used herein, "substituted" means that at least one hydrogen of a compound is replaced by (e.g., selected from) the following substituents: a halogen atom (F, Cl, Br or I), a hydroxyl group, a C1-C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azido group, an amidine group, a hydrazine group, a hydrazone group, a carbonyl group, a carbamoyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphate group or a salt thereof, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C6-C20 aryl group, a C3-C20 cycloalkyl group, a C3-C20 cycloalkenyl group, a C3-C20 cycloalkynyl group, a C2-C20 heterocycloalkyl group, a C2-C20 heterocycloalkenyl group, a C2-C20 heterocycloalkynyl group, a C3-C20 heteroaryl group and / or any suitable combination thereof. Herein, for example, C1-C20 means having 1 to 20 carbon atoms. As used herein, “active mass density of the negative electrode” is a value calculated by dividing the weight of components (active material, conductive material, binder, etc.) in the negative electrode excluding the negative electrode current collector by its volume. As used herein, if (eg, when) no definition is otherwise provided, in a chemical formula, if (eg, when) a chemical bond should be given but is not drawn, then a hydrogen atom is bonded to that position. As used herein, "fluoroalkyl" refers to an alkyl group in which some or all of the hydrogen atoms are replaced by fluorine atoms. As used herein, "perfluoroalkyl" refers to an alkyl group in which all hydrogen atoms are replaced by fluorine atoms. Rechargeable lithium battery Some embodiments provide a rechargeable lithium battery, comprising: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte. The active mass density of the negative electrode may be greater than or equal to about 1.7 g / cc, and the electrolyte comprises: a lithium salt; a non-aqueous organic solvent; a first additive represented by Chemical Formula 1; and a second additive represented by Chemical Formula 2: Chemical formula 1 R 1 -OR 2 Chemical formula 2 The first additive and the second additive may each function as a surfactant having both a hydrophilic group and a hydrophobic group in one molecule (eg, having both a hydrophilic group and a hydrophobic group). The first additive includes a central oxygen atom (eg, an ether group) and fluorine atoms or C1-C10 fluoroalkyl groups on both sides (eg, opposite sides) of the oxygen atom. Herein, the ether group is a hydrophilic group, and the fluorine atom and the C1-C10 fluoroalkyl group are hydrophobic groups. In one or more embodiments, the second additive includes a keto group at the center and fluorine atoms or C1-C10 fluoroalkyl groups at both sides (eg, opposite sides) of the keto group. Herein, the keto group is a hydrophilic group, and the fluorine atoms and C1-C10 fluoroalkyl groups are hydrophobic groups. Accordingly, if (for example, when) an electrolyte including the first additive and the second additive is used, wettability of the positive electrode and the negative electrode is improved, and lithium cations (Li ions) are uniformly (substantially uniformly) formed at the interface between the positive electrode and the electrolyte. + ), and form a stable solid electrolyte interface (SEI) film at the interface between the negative electrode and the electrolyte, thereby inhibiting or reducing the precipitation of lithium dendrites. Therefore, if (for example, when) an electrolyte including both the first additive and the second additive (for example, including the first additive and the second additive at the same time) is used, the increase in battery thickness and the decrease in cycle life can be suppressed or reduced by increasing the active mass density of the negative electrode to 1.7 g / cc or greater. Hereinafter, a rechargeable lithium battery according to one or more embodiments will be described in more detail. Active mass density of negative electrode Typically suitable rechargeable lithium batteries use a negative electrode having an active mass density of less than about 1.7 g / cc, but rechargeable lithium batteries according to one or more embodiments use a negative electrode having an active mass density (e.g., a mixture density or an active mass density of a mixture) greater than or equal to about 1.7 g / cc. The upper limit of the active mass density of the negative electrode is not particularly limited, but may be less than or equal to about 2.0 g / cc, less than or equal to about 1.9 g / cc, or less than or equal to about 1.8 g / cc. Charging upper limit voltage In a rechargeable lithium battery according to one or more embodiments, by using an electrolyte including both a first additive and a second additive (e.g., including the first additive and the second additive at the same time), an increase in battery thickness and a decrease in cycle life can be suppressed or reduced even when (e.g., when) the active mass density of the negative electrode increases. For example, a rechargeable lithium battery may have a charge upper limit voltage greater than or equal to about 4.5V. First Additive In Chemical Formula 1, R 1 and R 2 Each independently may be a fluorine atom or a C1-C10 fluoroalkyl group. For example, R 1 It may be a fluoroalkyl group having 2 carbon atoms. In addition, R 2It may be a fluoroalkyl group having 3 carbon atoms. The first additive can be represented by Chemical Formula 1-1: Chemical formula 1-1 In Chemical Formula 1-1, R 11 ~R 15 may be independently a hydrogen atom or a fluorine atom, provided that R 11 ~R 15 At least one of (for example, selected from R 11 ~R 15 One or more of ) is a fluorine atom; and R 21 ~R 27 may be independently a hydrogen atom or a fluorine atom, provided that R 21 ~R 27 At least one of (for example, selected from R 21 ~R 27 One or more of ) is a fluorine atom. A representative example of the first additive can be represented by Chemical Formula 1-1-1: Chemical formula 1-1-1 Second additive In chemical formula 2, R 3 and R 4 Each independently may be a fluorine atom or a C1-C10 fluoroalkyl group. For example, R 3 It may be a fluoroalkyl group having 2 carbon atoms, for example, a perfluoroalkyl group having 2 carbon atoms. In addition, R 4 It may be a fluoroalkyl group having 3 carbon atoms, for example, a perfluoroalkyl group having 3 carbon atoms. The second additive can be represented by Chemical Formula 2-1: Chemical formula 2-1 In Chemical Formula 2-1, R 31 ~R 35 may be independently a hydrogen atom or a fluorine atom, provided that R 31 ~R 35 At least one of (for example, selected from R 31 ~R 35 One or more of ) is a fluorine atom; and R 41 ~R 47 may be independently a hydrogen atom or a fluorine atom, provided that R 41 ~R 47 At least one of (for example, selected from R 41 ~R47 One or more of ) is a fluorine atom. A representative example of the second additive can be represented by Chemical Formula 2-1-1: Chemical formula 2-1-1 Content of the first additive and the second additive The first additive may be included in an amount of about 1 wt % to about 20 wt %, about 1 wt % to about 15 wt %, or about 1 wt % to about 10 wt %, based on the total amount of the electrolyte. If (e.g., when) the first additive is included in an amount exceeding the described range, the viscosity of the electrolyte including the first additive may be excessively (or significantly) increased, and the wettability of the positive electrode and the negative electrode may actually be reduced. In contrast, if (e.g., when) the first additive is included in an amount less than the described range (e.g., a small amount below the described range), the effect as a surfactant may be minimized. The second additive may be included in an amount of about 1 wt % to about 10 wt %, about 1 wt % to about 7 wt %, or about 1 wt % to about 5 wt %, based on the total amount of the electrolyte. If (e.g., when) the second additive is included in an amount exceeding the described range, the viscosity of the electrolyte including the second additive may be excessively (or significantly) increased, and the wettability of the positive electrode and the negative electrode may actually be reduced. In contrast, if (e.g., when) the second additive is included in an amount less than the described range (e.g., a small amount below the described range), the effect as a surfactant may be minimized. The weight ratio of the first additive to the second additive may be about 20:1 to about 2:1, about 15:1 to about 2:1, or about 10:1 to about 2:1. Within this range, aspects of the first additive and the second additive may enhance (eg, coordinate or synergize) each other. Non-aqueous organic solvents The nonaqueous organic solvent serves as a medium for transmitting ions participating in the electrochemical reaction of the battery. The non-aqueous organic solvent may include a carbonate solvent, an ester solvent, an ether solvent (eg, a propionate solvent), a ketone solvent, an alcohol solvent, an aprotic solvent, and / or combinations thereof (eg, any appropriate combination). Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate (EP), propyl propionate (PP), decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitriles (such as R-CN, where R is a C2-C20 straight chain hydrocarbon group, a branched hydrocarbon group, or a cyclic hydrocarbon group, and may include a double bond, an aromatic ring, or an ether group), amides (such as dimethylformamide), dioxolanes (such as 1,3-dioxolanes or 1,4-dioxolanes), sulfolane, etc. The nonaqueous organic solvent may be used alone or in combination of two or more thereof. For example, the non-aqueous organic solvent may include a carbonate-based solvent and a propionate-based solvent. The propionate-based solvent may be included in an amount of about 70 volume % or more based on the total amount of the non-aqueous organic solvent. In this case, relatively high voltage and / or relatively high temperature characteristics of the rechargeable lithium battery may be improved. In some embodiments, the non-aqueous organic solvent may be a mixed solvent of ethylene carbonate (EC), propylene carbonate (PC), ethyl propionate (EP), and propyl propionate (PP). Lithium salts The lithium salt dissolved in the nonaqueous organic solvent supplies lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. LiPF6 can be used as a lithium salt. The concentration of the lithium salt may be about 0.1M to about 2.0M. Positive electrode active material The positive electrode active material may be a compound capable of inserting / extracting lithium (lithiated inserting compound). For example, a composite oxide of lithium and one or more types (kinds) of metals (e.g., selected from) cobalt, manganese, nickel and / or a combination thereof (e.g., any appropriate combination) may be used. The composite oxide may be a lithium transition metal composite oxide, and specific examples may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides and / or combinations thereof (e.g., any appropriate combination). As an example, a compound represented by any one of the following chemical formulas may be used as the positive electrode active material: 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 NeG 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 Mn 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);Li a FePO4(0.90≤a≤1.8). In the described chemical formula, A is Ni, Co, Mn and / or a combination thereof (e.g., any suitable combination); X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element and / or a combination thereof (e.g., any suitable combination); D is O, F, S, P and / or a combination thereof (e.g., any suitable combination); G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., any suitable combination); and L 1 is Mn, Al, and / or combinations thereof (eg, any suitable combination). As an example, based on 100 mol% of metals excluding lithium in the lithium transition metal composite oxide, the positive electrode active material may have a nickel content (e.g., amount) of greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol%, and may be a relatively high nickel-based positive electrode active material having a nickel content of less than or equal to about 99 mol%. The relatively high nickel-based positive electrode active material can achieve a relatively high capacity and can be applied to a relatively high capacity, relatively high density rechargeable lithium battery. The positive electrode active material may be, for example, a lithium nickel-based oxide represented by Chemical Formula 11, a lithium cobalt-based oxide represented by Chemical Formula 12, a lithium iron phosphate-based compound represented by Chemical Formula 13, a cobalt-free lithium nickel manganese-based oxide represented by Chemical Formula 14, and / or combinations thereof (e.g., any appropriate combination). Chemical formula 11 Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 In Chemical Formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, M 1 and M 2 Each may independently be (for example, selected from) one or more elements of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W and Zr, and X may be (for example, selected from) one or more elements of F, P and S. In Chemical Formula 11, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2. Chemical formula 12 Li a2 Co x2 M 3 y2 O 2-b2 X b2 In Chemical formula 12, 0.9 ≤ a2 ≤ 1.8, 0.7 ≤ x2 ≤ 1, 0 ≤ y2 ≤ 0.3, 0.9 ≤ x2 + y2 ≤ 1.1, and 0 ≤ b2 ≤ 0.1, M 3 is one or more elements selected from, for example, Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from, for example, F, P, and S. Chemical formula 13 Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 In Chemical formula 13, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, 0.9 ≤ x3 + y3 ≤ 1.1, and 0 ≤ b3 ≤ 0.1, M 4 is selected from one or more elements of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is selected from one or more elements of F, P, and S. Chemical formula 14 Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4 In Chemical formula 14, 0.9 ≤ a2 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1. M 5 is selected from one or more elements of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is selected from one or more elements of F, P, and S. In particular, the electrolyte of the described embodiments can significantly improve the relatively high voltage and / or relatively high temperature characteristics of a battery using a lithium cobalt-based oxide represented by Chemical formula 12. Positive electrode A positive electrode for a rechargeable lithium battery may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material, and may further include a binder and / or a conductive material. For example, the positive electrode may further include an additive that may function as a sacrificial positive electrode. The content (eg, amount) of the positive electrode active material may be about 90 wt % to about 99 wt % based on 100 wt % of the positive electrode active material layer, and the content (eg, amount) of the binder and the conductive material may be about 0.5 wt % to about 5 wt %, respectively. The binder is used to attach the positive electrode active material particles to each other well, and also to attach the positive electrode active material to the positive electrode current collector well. Examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin, nylon, etc. as non-limiting examples. Conductive materials can be used to impart electrical conductivity (e.g., electrical conductivity) to the electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in the battery. Examples of conductive materials may include carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes); metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber (or providing metal powder or metal fiber); conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., any appropriate mixture). Al foil may be used as a positive electrode current collector, but the present disclosure is not limited thereto. Negative electrode active material The negative electrode active material may be a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide. The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any suitable combination). The crystalline carbon may be graphite (such as amorphous, flaky, sheet-like, spherical or fibrous natural graphite or artificial graphite). The amorphous carbon may be soft carbon, hard carbon, a mesophase pitch carbonization product, calcined coke, etc. The lithium metal alloy may include 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. The material capable of doping / dedoping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and / or combinations thereof (e.g., any suitable combination)). The Sn-based negative electrode active material may include Sn, SnO2, SnO x (0 < x < 2), Sn-based alloys, and / or combinations thereof (e.g., any suitable combination). The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles (or provide silicon particles and amorphous carbon coated on the surface of the silicon particles). For example, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are assembled and an amorphous carbon coating (shell) on the surface of the secondary particles. The amorphous carbon is also 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. 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 an amorphous carbon coating on the surface of the core. 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. Negative electrode The negative electrode for a rechargeable lithium battery includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material. For example, the negative electrode active material layer may include, based on 100 wt% of the negative electrode active material layer, about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material. The binder may be used to attach the negative electrode active material particles to each other well and also to attach the negative electrode active material well to the negative electrode current collector. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, and / or combinations thereof (e.g., any suitable combination). 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, and / or combinations thereof (eg, any suitable combination). The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, 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 and / or combinations thereof (e.g., any suitable combination). If (for example, when) an aqueous binder is used as a binder in the negative electrode active material layer, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound includes one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may be Na, K, or Li. The dry binder may be a polymer material capable of fiberization, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or combinations thereof (eg, any appropriate combination). A conductive material is included to provide electrode conductivity, and any conductive material can be used as the conductive material unless it causes a chemical change. Examples of the conductive material may be a carbon-based material (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); a metal-based material containing copper, nickel, aluminum, silver, etc. in the form of a metal powder or metal fiber (providing a metal powder or metal fiber); a conductive polymer (such as a polyphenylene derivative); and / or a mixture thereof (e.g., any appropriate mixture). The negative electrode current collector may include one selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or a combination thereof (eg, any appropriate combination), but the present disclosure is not limited thereto. Diaphragm Depending on the type or kind of rechargeable lithium battery, the separator may be present between the positive electrode and the negative electrode. The separator may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator), etc. The separator may include a porous substrate and a coating on one or both surfaces (eg, opposite surfaces) of the porous substrate, the coating including an organic material, an inorganic material, and / or a combination thereof (eg, any suitable combination). The porous substrate may be a polymer film formed from any one selected from the following: 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 copolymers or mixtures of two or more thereof (e.g., any suitable copolymers or mixtures of two or more thereof). The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer. 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 and / or combinations thereof (e.g., any suitable combination), but the present disclosure is not limited thereto. An organic material and an inorganic material may be mixed in one coating layer, or a coating layer including an organic material and a coating layer including an inorganic material may be stacked. Rechargeable lithium battery Rechargeable lithium batteries may be classified into cylindrical batteries, prismatic batteries, pouch-type or type batteries, coin-type or type batteries, etc., depending on the shape of the rechargeable lithium batteries. Figure 1 to Figure 4 A schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments. Figure 1 A cylindrical battery is shown, Figure 2 A prismatic cell is shown, and Figure 3 and Figure 4 Shows pouch type or kind of battery. Figure 1 to Figure 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 and a case 50 in which the electrode assembly 40 is accommodated, the battery assembly 40 including a separator 30 between a positive electrode 10 and a negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. Figure 1 As shown, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. Figure 2 In the embodiment, 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 3As shown, the rechargeable lithium battery 100 may include a positive electrode tab 71 and a negative electrode tab 72 serving as an electrical path for guiding current formed in the electrode assembly 40 to the outside. Figure 4 As shown, the rechargeable lithium battery 100 may include an electrode tab 70 serving as an electrical path for guiding current formed in the electrode assembly 40 to the outside. The rechargeable lithium battery according to one or more embodiments may be applied to automobiles, mobile phones, and / or one or more appropriate types (kinds) of electronic devices, but the present disclosure is not limited thereto. Terms such as "substantially," "about," and "approximately" are used as relative terms rather than 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 and an acceptable range of deviation determined by one of ordinary skill in the art taking 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. The numerical ranges disclosed herein include and are intended to disclose all sub-ranges of the same numerical precision. For example, the range of "1.0 to 10.0" includes all sub-ranges with 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. Therefore, the applicant reserves the right to amend this specification (including the claims) to explicitly set forth any sub-ranges contained within the range explicitly set forth herein. Hereinafter, examples and comparative examples of the present disclosure are described. However, these examples are by no means interpreted as limiting the scope of the present disclosure. Example Examples and Comparative Examples The electrolyte and rechargeable lithium battery cells were prepared as follows. Example 1 (1) Preparation of electrolyte

[0118] 1.3 M LiPF6 was dissolved in a non-aqueous organic solvent in which ethylene carbonate (EC), propylene carbonate (PC), ethyl propionate (EP) and propyl propionate (PP) were mixed in a volume ratio of about 10:15:30:45, and 10 wt % of a first additive and 1 wt % of a second additive based on the total amount of the electrolyte were added thereto to prepare an electrolyte. A first additive represented by Chemical Formula 1-1-1 is used, and a second additive represented by Chemical Formula 2-1-1 is used: Chemical formula 1-1-1 1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (CAS No.: 16627-68-2) Chemical formula 2-1-1 Perfluoro(2-methyl-3-pentanone) (CAS No.: 756-13-8) (2) Manufacturing of rechargeable lithium battery cells LiCoO 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, respectively, and then dispersed in N-methylpyrrolidone to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated on a 15 micrometer (μm) thick Al foil, dried at 100° C., and pressed to manufacture a positive electrode. Artificial graphite as a negative electrode active material, a styrene-butadiene rubber binder, and carboxymethyl cellulose were dispersed in distilled water at a weight ratio of 98:1:1 to prepare a negative electrode active material slurry. The negative electrode active material slurry was coated on a 10 μm thick Cu foil, dried at 100° C., and pressed to produce a negative electrode. Accordingly, the active mass density of the negative electrode was set to 1.7 grams per cubic centimeter (g / cc). An electrode assembly was manufactured by assembling a positive electrode, a negative electrode, and a separator made of polyethylene having a thickness of 10 μm, and an electrolyte was injected to manufacture a rechargeable lithium battery cell. Example 2 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 10 wt % of the first additive and 2 wt % of the second additive were added to prepare the electrolyte. Example 3 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 10 wt % of the first additive and 5 wt % of the second additive were added to prepare the electrolyte. Example 4 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as Example 1, except that 10 wt % of the first additive and 2 wt % of the second additive were added to prepare the electrolyte and the active mass density was set to 1.75 g / cc to prepare the negative electrode. Example 5 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as Example 1, except that 10 wt % of the first additive and 2 wt % of the second additive were added to prepare the electrolyte and the active mass density was set to 1.8 g / cc to prepare the negative electrode. Comparative Example 1 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added to prepare the electrolyte and the active mass density was set to 1.65 g / cc to prepare the negative electrode. Comparative Example 2 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added to prepare the electrolyte and the active mass density was set to 1.67 g / cc to prepare the negative electrode. Comparative Example 3 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that no additive was added to prepare the electrolyte and the active mass density was set to 1.7 g / cc to prepare the negative electrode. Comparative Example 4 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 15 wt % of the first additive was added to prepare the electrolyte and the active mass density was set to 1.7 g / cc to prepare the negative electrode. Comparative Example 5 An electrolyte and a rechargeable lithium battery cell were prepared in substantially the same manner as in Example 1, except that 10 wt % of the second additive was added when preparing the electrolyte and the active mass density was set to 1.7 g / cc to prepare a negative electrode. Evaluation Example The negative electrodes and the rechargeable lithium battery cells were evaluated in the following manner. Evaluation 1: Impregnation characteristics of electrolyte for negative electrode The negative electrode according to Example 1 was manufactured as a sample of width * length = 3 cm * 5 cm. 1 g of the electrolyte according to Example 1 was dropped on the sample and allowed to stand for 20 minutes. Thereafter, the amount of electrolyte immersed in the sample in 100 wt % of the electrolyte dropped on the sample was evaluated as a value selected from 0 to 5 according to the following standard, and the evaluation results are shown in Table 1. 0: If (for example, when) the amount of the electrolyte immersed in the sample is 0 wt % or more and less than 10 wt % 1: If (for example, when) the amount of the electrolyte immersed in the sample is 10 wt % or more and less than 20 wt % 2: If (for example, when) the amount of the electrolyte immersed in the sample is 20 wt % or more and less than 40 wt % 3: If (for example, when) the amount of the electrolyte immersed in the sample is 40 wt % or more and less than 60 wt % 4: If (for example, when) the amount of the electrolyte immersed in the sample is 60 wt % or more and less than 80 wt % 5: If (for example, when) the amount of the electrolyte immersed in the sample is 80 wt % or more and less than 100 wt % Each of the negative electrodes according to Example 2 to Example 5 and Comparative Examples 1 to Comparative Examples 5 was evaluated in substantially the same manner as in Evaluation 1, and the evaluation results are shown in Table 1. Table 1 Evaluation 2: Evaluation of room temperature charge and discharge cycle characteristics The rechargeable lithium battery cell was charged and discharged about 400 times under the conditions of 25° C., 2.0 C charge (CC / CV, 4.53 V, 0.025 C cutoff) / 1.0 C discharge (CC, 3 V cutoff). The thickness increase rate was calculated according to Equation 1, the capacity retention rate (cycle life) was calculated according to Equation 2, and the results are shown in Table 2. Equation 1 Thickness increase rate = {(full charge thickness after 400th cycle) - full charge thickness after 1st cycle)} / (full charge thickness after 1st cycle) × 100 In Equation 1, “full charge thickness” refers to the thickness of the rechargeable lithium battery cell measured after charging at SOC 100% (if (eg, when) the total charge capacity of the rechargeable lithium battery cell is set to 100%, charged to 100% charge capacity) after each cycle. Equation 2 Capacity retention rate = (discharge capacity after 400th cycle / discharge capacity after 1st cycle) × 100 Table 2 Summarize Referring to Tables 1 and 2, if (for example, when) an electrolyte that does not include additives (for example, an electrolyte that does not include additives at all) is used (Comparative Examples 1 to 3), the active mass density of the negative electrode increases from 1.65 g / cc to 1.7 g / cc, the impregnation characteristics of the electrolyte to the negative electrode decrease, the thickness of the rechargeable lithium battery cell increases, and the cycle life of each rechargeable lithium battery cell decreases. However, if (for example, when) the active mass density of the negative electrode is set identically at 1.7 g / cc, the electrolyte including the additive (Examples 1 to 3) exhibits increased impregnation properties of the electrolyte into the negative electrode, reduced thickness of the rechargeable lithium battery cell, and increased cycle life, compared to the electrolyte not including the additive (for example, the electrolyte not including the additive at all) (Comparative Example 3). In contrast, the electrolytes using only one of the first additive and the second additive (Comparative Examples 4 and 5) each unstably formed a solid electrolyte interface (SEI) film on the negative electrode surface, resulting in the growth of lithium dendrites, and thus, the capacity retention rate during charge and discharge was sharply deteriorated. Accordingly, it is shown that the use of an electrolyte that simultaneously (e.g., synchronously) includes the first additive and the second additive will be highly desirable or necessary. In addition, in an electrolyte that simultaneously (e.g., synchronously) includes the first additive and the second additive, even if the active mass density of the negative electrode is increased from 1.7 g / cc to 1.8 g / cc (Examples 4 and 5), the electrolyte still inhibits or reduces the increase in thickness and the reduction in cycle life of the rechargeable lithium battery cell. The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present invention disclosed herein may be implemented using any appropriate hardware, firmware (e.g., a dedicated integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the device may be formed on an integrated circuit (IC) chip or on separate IC chips. Further, the various 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 various components of the device may be processes or threads running on one or more processors in one or more computing devices, which execute computer program instructions and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented in a 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. Moreover, it should be recognized by those skilled in the art that the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed on one or more other computing devices without departing from the scope of the present disclosure. While the disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it should be understood that the disclosure should not be limited to the disclosed embodiments, but, on the contrary, the disclosure is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents.

Claims

1. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and Electrolyte, in The active mass density of the negative electrode is greater than or equal to 1.7 grams per cubic centimeter, and The electrolyte comprises: Lithium salts; Non-aqueous organic solvents; a first additive represented by Chemical Formula 1; and The second additive represented by Chemical Formula 2: Chemical formula 1 R 1 -O-R 2 In Chemical Formula 1, R 1 and R 2 Each is independently a fluorine atom or a C1-C10 fluoroalkyl group; Chemical formula 2 In chemical formula 2, R 3 and R 4 Each is independently a fluorine atom or a C1-C10 fluoroalkyl group.

2. The rechargeable lithium battery of claim 1, wherein The first additive is represented by chemical formula 1-1: Chemical formula 1-1 In Chemical Formula 1-1, R 11 ~R 15 are each a hydrogen atom or a fluorine atom and are selected from R 11 ~R 15 At least one of is a fluorine atom; and R 21 ~R 27 are each a hydrogen atom or a fluorine atom and are selected from R 21 ~R 27 At least one of them is a fluorine atom.

3. The rechargeable lithium battery of claim 1, wherein The first additive is represented by chemical formula 1-1-1: Chemical formula 1-1-1 4. The rechargeable lithium battery of claim 1, wherein The second additive is represented by chemical formula 2-1: Chemical formula 2-1 In chemical formula 2-1, R 31 ~R 35 are each a hydrogen atom or a fluorine atom and are selected from R 31 ~R 35 At least one of is a fluorine atom; and R 41 ~R 47 are each a hydrogen atom or a fluorine atom and are selected from R 41 ~R 47 At least one of them is a fluorine atom.

5. The rechargeable lithium battery of claim 1, wherein The second additive is represented by chemical formula 2-1-1: Chemical formula 2-1-1 6. The rechargeable lithium battery of claim 1, wherein The electrolyte includes the first additive in an amount of 1 wt % to 20 wt % based on a total amount of the electrolyte.

7. The rechargeable lithium battery of claim 1, wherein The electrolyte includes the second additive in an amount of 1 wt % to 10 wt % based on the total amount of the electrolyte.

8. The rechargeable lithium battery of claim 1, wherein The weight ratio of the first additive to the second additive is 20:1 to 2:

1.

9. The rechargeable lithium battery of claim 1, wherein The non-aqueous organic solvent includes carbonate solvents and propionate solvents.

10. The rechargeable lithium battery of claim 9, wherein The non-aqueous organic solvent includes the propionate-based solvent in an amount greater than or equal to 70 volume % based on the total amount of the non-aqueous organic solvent.

11. The rechargeable lithium battery of claim 1, wherein The lithium salt is LiPF6.

12. The rechargeable lithium battery of claim 1, wherein The concentration of the lithium salt is 0.1M to 2.0M.

13. The rechargeable lithium battery of claim 1, wherein The positive electrode active material includes lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, lithium nickel manganese oxide without cobalt and / or a combination thereof.

14. The rechargeable lithium battery of claim 1, wherein The negative electrode active material includes a carbon-based negative electrode active material, a Si-based negative electrode active material or a combination thereof.

15. The rechargeable lithium battery of claim 1, wherein The rechargeable lithium battery has a charge upper limit voltage greater than or equal to 4.5V.

16. The rechargeable lithium battery of claim 1, wherein The active mass density of the negative electrode is 1.7 g / cm3 to 2.0 g / cm3.

17. An electrolyte, comprising: Lithium salts; Non-aqueous organic solvents; A first additive represented by Chemical Formula 1; and The second additive represented by Chemical Formula 2: Chemical formula 1 R 1 -O-R 2 In Chemical Formula 1, R 1 and R 2 Each is independently a fluorine atom or a C1-C10 fluoroalkyl group; Chemical formula 2 In chemical formula 2, R 3 and R 4 Each is independently a fluorine atom or a C1-C10 fluoroalkyl group. The electrolyte is used in a rechargeable lithium battery.

18. The electrolyte of claim 17, wherein The electrolyte includes a first additive in an amount of 1 wt % to 20 wt % based on a total amount of the electrolyte, and a second additive in an amount of 1 wt % to 10 wt % based on a total amount of the electrolyte.

19. The electrolyte of claim 17, wherein The weight ratio of the first additive to the second additive is 20:1 to 2:

1.

20. The electrolyte of claim 17, wherein The non-aqueous organic solvent includes carbonate solvents and propionate solvents.

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