Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. A rechargeable lithium battery includes an electrolyte. The electrolyte comprises a non-aqueous organic solvent, a lithium salt and an additive comprising an azide group and a sulfonyl group substituted by a halogen element.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0154751 filed on November 9, 2023 in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of the present disclosure described herein relate to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. Background Art

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

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode and the negative electrode each include an active material in which intercalation and deintercalation can be performed, and if (eg, when) lithium ions are intercalated and deintercalated, electric energy due to oxidation and reduction reactions is generated.

[0006] Lithium salts dissolved in non-aqueous organic solvents are used as electrolytes for rechargeable lithium batteries. Rechargeable lithium batteries exhibit characteristics based on complex reactions between a positive electrode and an electrolyte and between a negative electrode and an electrolyte. Accordingly, using a suitable or appropriate electrolyte is an important means for improving rechargeable lithium batteries. Summary of the invention

[0007] Aspects according to one or more embodiments relate to an electrolyte for a rechargeable lithium battery having improved lifespan and stability.

[0008] Aspects according to one or more embodiments 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; and an additive including an azide group and a sulfonyl group substituted with a halogen element.

[0011] 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; and an additive including an azide group and a sulfonyl group substituted with a halogen element. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A simplified conceptual diagram showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0013] Figure 2 to Figure 5 A simplified cross-sectional view showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0014] Figure 6 A graph showing test results of lithium symmetrical battery cells according to electrolytes of Embodiment 3 and Comparative Example 1 is illustrated.

[0015] Fig. 7A A graph showing the results of negative electrode cyclic voltammetry (CV) of the electrolytes according to Embodiment 3 and Comparative Example 1 is illustrated.

[0016] Figure 7B Graphs showing the results of positive electrode cyclic voltammetry (CV) of electrolytes according to Embodiment 3 and Comparative Example 1 are illustrated.

[0017] Figure 8 A graph showing the linear sweep voltammetry (LSV) evaluation results of Embodiment 3 and Comparative Example 1 is illustrated. DETAILED DESCRIPTION

[0018] In order to fully understand the configuration and effects of the present disclosure, one or more embodiments of the present disclosure will be described with reference to the attached drawings. However, it should be noted that the present disclosure is not limited to the following example embodiments and can be implemented in one or more suitable forms. On the contrary, the example embodiments are provided only to disclose the present disclosure and to allow those skilled in the art to fully understand the scope of the present disclosure.

[0019] 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 there may be an intervening element between them. In the accompanying drawings, the thickness of some components is exaggerated in order to effectively explain the technical content. The same reference numerals refer to the same elements throughout, and a repeated description thereof may not be provided in the specification.

[0020] Unless otherwise specifically stated in the description, an expression in a singular form may include an expression in a plural form. In addition, unless otherwise specifically stated, the phrase "A or B" may indicate "A but not B", "B but not A" and "A and B". The terms "comprises / includes" and / or "comprising / including" used in the description do not exclude the existence or addition of one or more other components.

[0021] As used herein, expressions such as “at least one of,” “one of,” and “(e.g., selected from) of,” when preceding / following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, “at least one of a, b, and c,” “at least one selected from a, b, and c,” and the like 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.

[0022] The terms used in this article are intended only to describe specific embodiments and are not intended to limit the present disclosure. As used in this article, the singular forms "a", "an" and "said" are intended to include plural forms including "at least one", unless the content (e.g., amount) is clearly indicated in other ways. "At least one" should not be interpreted as being limited to the singular. As used in this article, the term "and / or" includes any and all combinations of one or more related enumerated items. The terms "includes", "including", "comprises" and / or "comprising", when used in the detailed description, indicate the presence of narrated features, regions, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and / or groups thereof.

[0023] Spatially relative terms, such as "below," "below," "below," "above," and "on" may be used herein to easily describe the relationship of one element or feature to 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, when the device in the drawings is turned over, elements described as "below" or "below" other elements or features will then be "above" or "on" other elements or features. In some embodiments, 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.

[0024] As used herein, the term "metal" includes all metals and metalloids, such as silicon and germanium, in either elemental or ionic form.

[0025] The term "alloy" as used herein refers to a mixture of two or more metals.

[0026] As used herein, the term "electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0027] As used herein, the term "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0028] The term "negative electrode active material" as used herein refers to a negative electrode material that can undergo lithiation and delithiation.

[0029] As used herein, "lithiate" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0030] As used herein, the terms "delithiate" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0031] As used herein, the terms "charge" and "charging" refer to the process of providing electrochemical energy to a battery.

[0032] As used herein, the terms "discharge" and "discharging" refer to the process of removing electrochemical energy from a battery.

[0033] The terms "positive electrode" and "cathode" as used herein refer to the electrode that undergoes electrochemical reduction and lithiation during the discharge process.

[0034] The terms "negative electrode" and "anode" as used herein refer to the electrode at which electrochemical oxidation and delithiation occur during the discharge process.

[0035] As used herein, the term "substantially" and similar terms are used as terms of approximation rather than as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that one of ordinary skill in the art would recognize. Also, "about" and similar terms, when used herein in conjunction with a value or range of values, include both the recited value and values ​​within an acceptable range of deviation for the particular value determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0036] Furthermore, any numerical range set forth in this article is intended to include all sub-ranges of the same numerical precision falling within the set forth range. For example, the range of "1.0-10.0" is intended to be included between the set forth minimum value 1.0 and the set forth maximum value 10.0 (and including the end value), that is, all sub-ranges (such as, for example, 2.4-7.6) having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0. Any maximum numerical limit set forth in this article is intended to include all lower numerical limits falling therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to modify this specification (including claims) to explicitly set forth any sub-range falling within the range explicitly set forth in this article.

[0037] As used herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of the components.

[0038] As used herein, if (e.g., when) no definition is otherwise provided, in a chemical formula, if (e.g., when) a chemical bond is not drawn at a position where a chemical bond should be drawn, a hydrogen atom is bonded to that position.

[0039] Figure 1 A simplified conceptual diagram showing 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.

[0040] The positive electrode 10 and the negative electrode 20 may be spaced and / or separated (e.g., spaced apart or separated) from each other via 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.

[0041] 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.

[0042] Positive electrode 10

[0043] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode collector COL1 and a positive electrode active material layer AML1 formed on the positive electrode collector COL1. The positive electrode active material layer AML1 may include a positive electrode active material, and may further include a binder and / or a conductive material.

[0044] For example, the positive electrode 10 may further include an additive that may function as a sacrificial positive electrode.

[0045] The amount of the positive electrode active material may be in the range of about 90 wt % to about 99.5 wt % based on about 100 wt % of the positive electrode active material layer AML1. The amount of the binder and the amount of the conductive material may each be in the range of about 0.5 wt % to about 5 wt % based on about 100 wt % of the positive electrode active material layer AML1.

[0046] 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 COL1. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin or nylon, but the present disclosure is not limited thereto.

[0047] 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. The conductive material may include, for example: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal powder or metal fiber containing one or more selected from copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and / or mixtures thereof (e.g., suitable mixtures thereof).

[0048] An aluminum (Al) foil may be used as the positive electrode current collector COL1 , but the present disclosure is not limited thereto.

[0049] Positive electrode active material

[0050] The positive electrode active material 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 / or a combination thereof (e.g., any suitable combination thereof).

[0051] The composite oxide may include a lithium transition metal composite oxide, such as a lithium nickel-based oxide, a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron phosphate-based compound, a cobalt-free nickel manganese-based oxide, and / or combinations thereof (eg, appropriate combinations thereof).

[0052] For example, in one or more embodiments, 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 GeO2(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 Mn1-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) and Li a FePO4(0.90≤a≤1.8).

[0053] In the above chemical formula, A is Ni, Co, Mn and / or a combination thereof (e.g., a suitable combination thereof), X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare element and / or a combination thereof (e.g., a suitable combination thereof), D is O, F, S, P and / or a combination thereof (e.g., a suitable combination thereof), G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or a combination thereof (e.g., a suitable combination thereof), and L 1 is Mn, Al and / or a combination thereof (eg, a suitable combination thereof).

[0054] For example, based on about 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) equal to or greater than about 80 mol%, equal to or greater than about 85 mol%, equal to or greater than about 90 mol%, equal to or greater than about 91 mol%, or equal to or greater than about 94 mol% and equal to or less than about 99 mol%. The high nickel-based positive electrode active material can achieve high capacity and can therefore be applied to high capacity and high energy density rechargeable lithium batteries.

[0055] Negative electrode 20

[0056] 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 (eg, an electron conductor).

[0057] For example, based on 100 wt % of the total weight of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include 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.

[0058] 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 COL2. The binder can include a non-aqueous binder, an aqueous binder, a dry binder and / or a combination thereof (e.g., any suitable combination thereof).

[0059] 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 thereof).

[0060] 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 and / or combinations thereof (e.g., any suitable combination thereof).

[0061] 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 selected from carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and alkali metal salts thereof. The alkali metal may include Na, K or Li.

[0062] The dry binder may include a polymer material capable of fiberization such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or combinations thereof (eg, any suitable combination thereof).

[0063] Conductive materials (e.g., electronic conductors) 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-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal powder or metal fiber including one or more selected from copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and / or mixtures thereof (e.g., any suitable combination thereof).

[0064] 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, and / or combinations thereof (eg, appropriate combinations thereof).

[0065] Negative electrode active material

[0066] The negative electrode active material may include: a material capable of reversibly inserting and extracting lithium ions, lithium metal, a lithium metal alloy, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0067] The material capable of reversibly inserting and extracting lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any suitable combination thereof). For example, crystalline carbon may include graphite (such as amorphous, flaky, lamellar, spherical, or fibrous natural or artificial graphite), and amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbon, or calcined coke.

[0068] 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.

[0069] The material capable of doping and dedoping 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 (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and / or a combination thereof (e.g., any suitable combination thereof)), and / or a combination thereof (e.g., any suitable 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.

[0070] 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 a structure of 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.

[0071] 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.

[0072] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0073] Separator 30

[0074] 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 selected from polyethylene, polypropylene, and polyvinylidene fluoride, and may have a multilayer separator thereof (such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and a polypropylene / polyethylene / polypropylene three-layer separator).

[0075] The separator 30 may include a porous substrate and a coating on one surface or the opposite surface of the porous substrate, the coating including an organic material, an inorganic material, and / or a combination thereof (eg, any appropriate combination thereof).

[0076] The porous substrate may be a polymer layer comprising one selected from polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon); or may be a copolymer or mixture of two or more of the above-mentioned materials.

[0077] The organic material may include a polyvinylidene fluoride-based copolymer or a (meth)acrylic acid copolymer.

[0078] 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 thereof), but the present disclosure is not limited thereto.

[0079] 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.

[0080] Electrolyte ELL

[0081] The electrolyte ELL for a rechargeable lithium battery may include a non-aqueous organic solvent and a lithium salt.

[0082] The nonaqueous organic solvent may be used as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0083] The non-aqueous organic solvent may include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or combinations thereof (eg, any appropriate combination thereof).

[0084] 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).

[0085] The ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, or caprolactone.

[0086] The ether solvent may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran or tetrahydrofuran. The ketone solvent may include cyclohexanone. The aprotic solvent may include a nitrile such as R-CN (wherein R is a hydrocarbon group having a C2 to C20 linear, branched or cyclic structure, and may include a double bond, an aromatic ring or an ether group); an amide (such as dimethylformamide); a dioxolane (such as 1,3-dioxolane or 1,4-dioxolane); or sulfolane.

[0087] The nonaqueous organic solvent may be used alone or as a mixture of two or more thereof.

[0088] In addition, if (for example, when) a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate may be mixed and used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of about 1:1 to about 1:9.

[0089] 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 achieving 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, bis(fluorosulfonyl)imide lithium (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are each an integer between 1 and 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB) and lithium bis(oxalato)borate (LiBOB).

[0090] Rechargeable lithium battery

[0091] Rechargeable lithium batteries may be classified into cylindrical batteries, prismatic batteries, pouch type(like) batteries, and coin type(like) batteries based on their shapes. Figure 2 to Figure 5 A simplified cross-sectional view showing a rechargeable lithium battery according to one or more embodiments is illustrated. Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 Pouch type battery is shown. Figure 2 to Figure 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 in which a separator 30 is disposed between a positive electrode 10 and a negative electrode 20, and may also include a case 50 in which the electrode assembly 40 is accommodated. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in an electrolyte. Figure 2 As illustrated, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. 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 and Figure 5 As shown, the rechargeable lithium battery 100 may include an electrode tab 70 , or a positive electrode tab 71 and a negative electrode tab 72 , which serve as an electrical path for guiding current generated in the electrode assembly 40 to the outside.

[0092] The electrolyte of the rechargeable lithium battery according to one or more embodiments of the present disclosure will be described in more detail below.

[0093] An electrolyte for a rechargeable lithium battery according to one or more embodiments may include: a non-aqueous organic solvent; a lithium salt; and an additive including an azide group and a sulfonyl group substituted with a halogen element.

[0094] The electrolyte may be prepared by a mixing process in which a lithium salt is dissolved in a non-aqueous organic solvent and an additive is added for mixing. The mixing process of the electrolyte may include any appropriate process in the field of electrolyte preparation, and those skilled in the art will be able to appropriately or properly select and use.

[0095] In one or more embodiments, a rechargeable lithium battery may be provided, comprising: a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, and an electrolyte, the electrolyte comprising: a non-aqueous organic solvent, a lithium salt, and an additive comprising an azide group and a sulfonyl group substituted with a halogen element.

[0096] 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).

[0097] The non-aqueous organic solvent may be, for example, a mixed solvent of ethylene carbonate (EC), propyl carbonate (PC), and propyl propionate (PP).

[0098] For example, based on the total volume of the non-aqueous organic solvent, the amount of ethylene carbonate (EC) included can be about 5 vol% to about 20 vol%. Based on the total volume of the non-aqueous organic solvent, the amount of propylene carbonate (PC) included can be about 10 vol% to about 30 vol%. Based on the total volume of the non-aqueous organic solvent, the amount of propyl propionate (PP) included can be about 50 vol% to about 80 vol%.

[0099] For example, the lithium salt may include LiPF6.

[0100] The lithium salt may have a concentration of about 0.1 M to about 2.0 M. For example, the lithium salt may have a concentration equal to or greater than about 0.5 M or about 1.0 M. The lithium salt may have a concentration equal to or less than about 2.0 M, equal to or less than about 1.7 M, or equal to or less than about 1.5 M. 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.

[0101] The additive may be a compound including an azide group and a sulfonyl group substituted by a halogen element. The azide group and the sulfonyl group substituted by a halogen element may allow a solid electrolyte interface (SEI) film (hereinafter, also referred to as a "protective layer" or "protective film") of a lithium salt to be formed on the surface of the negative electrode and the positive electrode, thereby reducing the interfacial resistance between the positive electrode and the electrolyte to accelerate the movement of lithium ions on the surface of the positive electrode, and inhibiting or reducing the decomposition of the negative electrode active material or the positive electrode active material. For example, as will be determined in the evaluation discussed herein, the additive may be reduced to a non-aqueous organic solvent to form a lithium salt SEI film on the surface of the negative electrode and the positive electrode, which may achieve passivation.

[0102] Based on the total amount of the electrolyte, the amount of the additive included may be about 0.02 wt% to about 2.0 wt%. For example, based on the total weight (100 wt%) of the electrolyte, the amount of the additive included may be about 0.1 wt% to about 1.5 wt%. Based on the total weight of the electrolyte, the amount of the additive included may be about 0.5 wt% to about 1.0 wt%. When the additive has the aforementioned concentration in the electrolyte, a protective film having a suitable or appropriate film resistance may be formed on the surface of the negative electrode and the positive electrode of the rechargeable lithium battery to improve the cycle characteristics of the rechargeable lithium battery.

[0103] The additive according to one or more embodiments of the present disclosure may be represented by Chemical Formula 1.

[0104] Chemical formula 1

[0105]

[0106] In Chemical Formula 1, n may be an integer between 1 and 5, and X may be a halogen element. The halogen element may include fluorine, bromine, chlorine, iodine, and the like.

[0107] For example, in the electrolyte for a rechargeable lithium battery according to the present disclosure, the additive may be represented by Chemical Formula 1-1.

[0108] Chemical formula 1-1

[0109]

[0110] The additive according to Chemical Formula 1-1 may have a compound structure including an azide group and a sulfonyl group substituted with a fluorine element, the azide group and the sulfonyl group serving as functional groups.

[0111] For example, since the additive has a structure including (e.g., simultaneously) both an azide group and a sulfonyl group substituted with a fluorine element, a lithium salt-based SEI film can be maintained on the surfaces of the negative electrode and the positive electrode, and the mobility of lithium ions can be increased to improve the stability and cycle life characteristics of the rechargeable lithium battery.

[0112] In a rechargeable lithium battery using an electrolyte according to the present disclosure, the positive electrode active material may include one or more selected from 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.

[0113] In a rechargeable lithium battery using the electrolyte according to the present disclosure, the negative electrode active material may include a carbon-based negative electrode active material, a silicon-based negative electrode active material, or any combination thereof.

[0114] The rechargeable lithium battery according to one or more embodiments of the present disclosure may be applied to a motor vehicle (eg, an electric car), a mobile phone, and / or any other electronic device, but the present disclosure is not limited thereto.

[0115] The following will describe examples / embodiments and comparative examples of the present disclosure. The following examples / embodiments are merely one or more embodiments / embodiments of the present disclosure, and the present disclosure is not limited to the following embodiments / embodiments.

[0116] Embodiments and Comparative Examples

[0117] Implementation Method 1

[0118] (1) Preparation of electrolyte

[0119] About 1.3 M of LiPF6 was dissolved in a non-aqueous organic solvent (in which ethylene carbonate (EC), propylene carbonate (PC) and propyl propionate (PP) were mixed in a volume ratio of about 10:15:75), and about 0.2 wt % of an additive was added based on the total weight of the electrolyte to prepare an electrolyte.

[0120] The material represented by Chemical Formula 1-1 is used as an additive.

[0121] Chemical formula 1-1

[0122]

[0123] For example, the additive according to Chemical Formula 1-1 can be prepared by the following synthesis example.

[0124] Synthesis example 1

[0125] First, after 2-chloroethanesulfonyl fluoride (about 9 g) is dissolved in dimethyl sulfoxide (DMSO) (about 25 mL), sodium azide (about 4 g) is added, and the mixture is stirred at room temperature (about 25 ° C.) for about 12 hours to prepare a reaction mixture. Afterwards, the reaction mixture is diluted with cold water (about 180 mL) and then extracted with ethyl acetate. Thereafter, the filtered organic layer is rinsed with saline, dried with Na2SO4, concentrated under reduced pressure, and then purified by column chromatography to obtain 2-azidoethyl-1-sulfonyl fluoride, or a compound represented by Chemical Formula 1-1.

[0126] (2) Preparation of rechargeable lithium batteries

[0127] Based on the total amount of dry matter in the positive electrode active material slurry, about 97wt% of LiCoO2 (LCO), about 0.5wt% of artificial graphite powder as a conductive material, about 0.8wt% of carbon black (Ketjen black), about 0.2wt% of acrylonitrile rubber and about 1.5wt% of polyvinylidene fluoride (PVdF) are mixed and added to N-methyl-2-pyrrolidone, and then stirred for about 30 minutes by using a mechanical stirrer to prepare a slurry of the positive electrode active material. The slurry is coated with a thickness of about 60μm on an aluminum positive electrode collector of about 20μm using a scraper, dried in a hot air dryer at about 100°C for about 0.5 hours, and then dried under vacuum conditions and at about 120°C for about 4 hours, and then rolled to prepare a positive electrode.

[0128] Based on the total amount of dry matter in the negative electrode active material slurry, about 98wt% of artificial graphite, about 1wt% of styrene-butadiene rubber (SBR) and about 1wt% of carboxymethyl cellulose (CMC) were mixed and added to distilled water, and then stirred for about 60 minutes by using a mechanical stirrer to prepare a slurry of the negative electrode active material. The slurry having a thickness of about 60μm was coated on a copper negative electrode current collector of about 10μm using a scraper, dried in a hot air dryer at about 100°C for about 0.5 hours, and then dried under vacuum conditions at about 120°C for about 4 hours, and then rolled to prepare a negative electrode.

[0129] The slurry of the negative electrode active material was coated on a copper (Cu) foil having a thickness of about 10 μm, dried at about 100° C., and then pressed to prepare a negative electrode.

[0130] The positive electrode, the negative electrode, and a polyethylene separator having a thickness of 10 μm were assembled to prepare an electrode assembly, and the electrolyte prepared by the above method was introduced to prepare a rechargeable lithium battery.

[0131] Implementation Method 2

[0132] The electrolyte and the rechargeable lithium battery were prepared by the same method as in Embodiment 1, except that about 0.5 wt % of the additive was used.

[0133] Implementation 3

[0134] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Embodiment 1, except that about 1.0 wt % of the additive was used.

[0135] Implementation 4

[0136] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Embodiment 1, except that about 2.0 wt % of the additive was used.

[0137] Comparative Example 1

[0138] The electrolyte and the rechargeable lithium battery are prepared by the same method as in Embodiment 1, except that if (eg, when) the electrolyte is prepared, the additive represented by Chemical Formula 1-1 is used.

[0139] Comparative Example 2

[0140] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Embodiment 3, except that the additive represented by Chemical Formula 2 was used as the electrolyte additive instead of the compound represented by Chemical Formula 1-1.

[0141] Chemical formula 2

[0142]

[0143] Comparative Example 3

[0144] An electrolyte and a rechargeable lithium battery were prepared by the same method as in Embodiment 3, except that the compound represented by Chemical Formula 3 was used as an electrolyte additive instead of the compound represented by Chemical Formula 1-1.

[0145] Chemical formula 3

[0146]

[0147] Evaluation Example

[0148] The rechargeable lithium batteries were evaluated by the following method.

[0149] Evaluation 1: Charge / discharge cycle characteristics

[0150] At about 25° C., the rechargeable lithium batteries prepared in the embodiments and comparative examples were each charged with a constant current at a rate of about 0.2C until the voltage was about 4.53 V (relative to Li), and then the current was cut off at a rate of about 0.05C in a constant voltage mode while the voltage was maintained at about 4.53 V. Then, the battery was discharged at a constant current of about 0.2C until the voltage was about 2.5 V (relative to Li) (formation process).

[0151] The high temperature charge / discharge characteristics of the rechargeable lithium battery that has undergone the formation process were evaluated. The rechargeable lithium battery was charged and discharged for 100 cycles (hereinafter referred to as "100 cycles") at about 45°C under the conditions of charging (about 1.5C / 4.53V, about 0.05C cutoff, standing for about 10 minutes) and discharging (about 0.5C / 2.5V cutoff, standing for about 10 minutes).

[0152] After measuring the initial discharge capacity and the discharge capacity after 100 cycles, the capacity retention ratio was calculated, and the results are shown in Table 1. The capacity retention ratio was calculated according to Equation 1.

[0153] Equation 1

[0154] Capacity retention rate (%) = (discharge capacity after 100 cycles / initial discharge capacity) × 100

[0155] Table 1

[0156]

[0157] Assessment 2: Lithium Dendrite Characteristics

[0158] The electrolytes used in Embodiment 3 and Comparative Example 1 were used to prepare Li / Li symmetric 2032-type (type) coin cells (ie, lithium symmetric cells).

[0159] A lithium symmetric battery cell test was performed to determine the lithium dendrite characteristics, and the results were as follows Figure 6 shown. Figure 6 A graph showing the test results of lithium symmetric battery cells according to the electrolytes of Embodiment 3 and Comparative Example 1 is illustrated. The lithium symmetric battery cell test was performed at a current density of about 2.5 mA / cm 2 and the scanning range was about 5 minutes.

[0160] Evaluation 3: CV Characteristics

[0161] Cyclic voltammetry (CV) was performed at room temperature (about 25° C.) to evaluate the electrochemical stability of the electrolytes used in Embodiment 3 and Comparative Example 1, and the results are shown in FIG. Fig. 7A and 7B shown. Fig. 7A A graph showing the results of cyclic voltammetry (CV) of the negative electrode according to Embodiment 3 and Comparative Example 1 is illustrated. Figure 7B Graphs showing the results of positive electrode cyclic voltammetry (CV) of the electrolytes according to Embodiment 3 and Comparative Example 1 are illustrated.

[0162] Negative electrode CV measurements were performed by using a coin half-cell unit, where a graphite negative electrode was used as a working electrode and a Li metal was used as a counter electrode. In this case, the scan was performed from about 3 V to about 0 V for 3 cycles with a scan rate of about 0.1 mV / sec.

[0163] Positive electrode CV measurements were performed by using a positive electrode coin half-cell, where the LCO positive electrode was used as the working electrode and lithium metal was used as the counter electrode. In this case, the scan was performed from about 3 V to about 4.6 V for 3 cycles with a scan rate of about 0.1 mV / sec.

[0164] Evaluation 4: Linear Sweep Voltammetry (LSV) Characteristics of the Battery

[0165] For the electrolytes prepared by Embodiment 3 and Comparative Example 1, oxidative electrode decomposition was evaluated using linear sweep voltammetry (LSV) at room temperature (about 25° C.).

[0166] A three-electrode beaker cell was used, in which a Pt electrode was used as a working electrode and Li metal was used as a counter electrode and a reference electrode. In this case, a scan was performed in the range of about 3.0 V to about 7.0 V at a rate of about 1 mV / sec. Figure 8 A graph showing the LSV evaluation results of Embodiment 3 and Comparative Example 1 is explained.

[0167] Comprehensive Assessment

[0168] Referring to Table 1, without being bound by any particular theory, it was determined that the capacity retention rate depending on the charge / discharge cycle was improved in each case (Embodiment 1 to Embodiment 4) using an electrolyte including the additive according to the present invention, as compared to the case of using an electrolyte to which no additive was added at all (Comparative Example 1).

[0169] Without being bound by any particular theory, it was determined that the capacity retention rate depending on the charge / discharge cycle was improved in the case where an electrolyte including the additive according to the present invention was used (Embodiment 1 to Embodiment 4), as compared to the case where an electrolyte not including any of the functional groups (such as an azide group and a sulfonyl group substituted with a halogen element) was used (Comparative Examples 2 and 3).

[0170] refer to Figure 6 Without being bound by any particular theory, it is determined that the life of the rechargeable lithium battery of Embodiment 3 is superior to that of the rechargeable lithium battery of Comparative Example 1. Therefore, without being bound by any particular theory, it is believed that adding the additive according to the present disclosure to the electrolyte will help inhibit or reduce the formation of lithium dendrites on the surface of the negative electrode. Fig. 7A and Figure 7B , it can be seen that the additive according to one or more embodiments forms a SEI film on the surface of the negative electrode and the positive electrode to achieve passivation. For example, referring to Fig. 7A Without being bound by any particular theory, it was determined that the electrolyte according to Comparative Example 1 exhibited a reduction decomposition peak at a lower potential than the electrolyte according to Embodiment 3. Therefore, without being bound by any particular theory, it is believed that the electrolyte according to Embodiment 3 allows the formation of an SEI film on the negative electrode in a wide voltage range before solvent decomposition occurs during a charging process in which lithium ions are intercalated into the negative electrode.

[0171] refer to Figure 8, the additive can be preferentially oxidized into an organic solvent that forms a protective layer on the surface of the positive electrode, and the protective layer can more effectively inhibit or reduce direct contact between the organic solvent and the positive electrode, which can lead to greater improvement in the reversibility of lithium ion insertion and extraction. Therefore, the additive can effectively contribute to the stability and cycle life characteristics of the rechargeable lithium battery.

[0172] The electrolyte according to one or more embodiments may use an additive including an azide group and a sulfonyl group substituted with a halogen element, and without being bound by any particular theory, it should exhibit such an effect that if (for example, when) the rechargeable battery is activated, the stability and life characteristics under high voltage conditions are improved.

[0173] In the present disclosure, "does not include one or any 'component'", "excludes one or any 'component'", "no 'component'" and the like mean that the "component" is not added, selected or used as a component in the composition or compound, but due to other impurities and / or external factors, the "component" may still be included in an amount less than the appropriate amount.

[0174] The battery management system (BMS) device and / or any other related device or component according to the embodiments of the present invention described 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, one or more appropriate components of the device may be formed on an integrated circuit (IC) chip or on a separate IC chip. Further, one or more appropriate 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, one or more appropriate components of the device may be a process or thread running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform one or more appropriate 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-temporary computer-readable media (such as, for example, a CD-ROM, a flash drive, etc.). Moreover, those skilled in the art should recognize that without departing from the scope of the present disclosure, the functions of one or more appropriate 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.

[0175] Although the present disclosure has been described in conjunction with what are currently considered to be embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments, but is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the appended claims, their equivalents, so the aforementioned 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; and Additives, including azide groups and sulfonyl groups substituted with halogen elements, The electrolyte is used in rechargeable lithium batteries.

2. The electrolyte according to claim 1, wherein the additive is represented by Chemical Formula 1, Chemical formula 1 Wherein in Chemical Formula 1, n is an integer between 1 and 5, and X is the halogen element.

3. The electrolyte according to claim 1, wherein the additive is represented by Chemical Formula 1-1, Chemical formula 1-1 4 . The electrolyte according to claim 1 , wherein the additive is included in an amount of 0.02 wt % to 2 wt % based on the total weight of the electrolyte.

5. The electrolyte of claim 1, wherein the nonaqueous organic solvent comprises one or more selected from the group consisting of ethylene carbonate, propylene carbonate, propyl propionate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, and butylene carbonate.

6. The electrolyte of claim 1, wherein the lithium salt comprises one or more 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 and LiC4F9SO3.

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

8. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and The electrolyte according to any one of claims 1 to 7.

9. The rechargeable lithium battery of claim 8, wherein the positive electrode active material comprises one or more 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. 10 . The rechargeable lithium battery of claim 8 , 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.

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