Compounds, electrolytes for rechargeable lithium batteries, and rechargeable lithium batteries including electrolytes

Abstract

This disclosure relates to compounds of Formula 1, electrolytes comprising the compounds for rechargeable lithium batteries, and rechargeable lithium batteries comprising the electrolytes. Formula 1

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0171050, filed on November 26, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to compounds, electrolytes for rechargeable lithium batteries, and rechargeable lithium batteries including electrolytes. Background Technology

[0004] With the increasing prevalence of battery-powered electronic devices (such as mobile phones, laptops, and electric vehicles), the demand for high-energy-density and high-capacity rechargeable batteries (e.g., rechargeable lithium-ion batteries) is also increasing. Accordingly, improving the performance of rechargeable lithium-ion batteries is advantageous.

[0005] A rechargeable lithium battery includes: a positive electrode and a negative electrode, which are active materials capable of inserting and deintercalating lithium ions; and an electrolyte, and generates electrical energy through oxidation and reduction reactions when lithium ions are inserted into / deintercalated from the positive electrode and the negative electrode.

[0006] As the electrolyte for this type of rechargeable lithium-ion battery, an electrolyte in which lithium salts are dissolved in a non-aqueous organic solvent is used. Rechargeable lithium-ion batteries exhibit battery characteristics through complex reactions between the positive electrode and the electrolyte, and between the negative electrode and the electrolyte. Therefore, using a desired electrolyte is a relevant parameter for improving the performance of rechargeable lithium-ion batteries. Summary of the Invention

[0007] One example implementation includes a compound in a rechargeable lithium battery that provides reduced resistance and reduced gas generation at high voltage and high temperature, and an electrolyte for a rechargeable lithium battery comprising the compound.

[0008] Another example implementation includes a rechargeable lithium battery containing an electrolyte.

[0009] One example implementation includes a compound of chemical formula 1 below.

[0010] Chemical Formula 1:

[0011] .

[0012] In chemical formula 1,

[0013] R 1 R 2 R 3 and R 4Each is defined as described below in this disclosure.

[0014] Another example embodiment includes an electrolyte for a rechargeable lithium battery, wherein the electrolyte comprises a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive comprises a compound of formula 1 below:

[0015] Chemical Formula 1:

[0016] .

[0017] In chemical formula 1,

[0018] R 1 R 2 R 3 and R 4 Each is defined as described below in this disclosure.

[0019] Another example implementation includes a rechargeable lithium battery comprising a positive electrode containing positive electrode active material, a negative electrode containing negative electrode active material, and the electrolyte discussed above. Attached Figure Description

[0020] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the detailed description of the present disclosure, further describe aspects and features of the present disclosure. Therefore, the present disclosure should not be construed as limited to the drawings, wherein:

[0021] Figure 1 A conceptual diagram of a rechargeable lithium battery according to an example embodiment of the present disclosure is shown for illustrative purposes.

[0022] Figures 2-5 A diagram illustrating a rechargeable lithium battery according to an example embodiment is shown for illustrative purposes. Detailed Implementation

[0023] To fully understand the configuration and effects of this disclosure, exemplary embodiments of the disclosure are described with reference to the accompanying drawings. However, it should be understood that the exemplary embodiments disclosed below can be embodied in various forms and modified in various ways, and are not limited to the exemplary embodiments described herein. The description of exemplary embodiments is provided only to ensure the completeness of this disclosure and to fully inform those skilled in the art of the scope of this disclosure.

[0024] In this specification, when any component is referred to as being "on" another component, this means that the component may be formed directly on the other component, or that a third component may be inserted between them. Furthermore, in the accompanying drawings, the dimensions (e.g., thickness) of components may be enlarged for the purpose of effectively describing the technical content. Throughout this specification, portions indicated by the same reference numerals denote the same components.

[0025] Unless otherwise stated in this specification, anything expressed in the singular may also include the plural. Furthermore, unless otherwise specifically stated herein, “A or B” may mean “including A, including B, or including both A and B.” As used in this specification, the terms “comprise” and / or “comprising” do not exclude the presence or addition of one or more other components.

[0026] In this specification, the term "combination thereof" may refer to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0027] Unless otherwise defined in this specification, the term "substitution" means that at least one hydrogen atom in a substituent or compound is replaced by: deuterium, halogen, hydroxyl, amino, C1-C30 amino, nitro, C1-C40 silyl, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C20 alkoxy, C1-C10 fluoroalkyl, cyano, or a combination thereof.

[0028] For example, the term "substitution" may mean that at least one hydrogen atom in a substituent or compound is replaced by: deuterium, halogroup, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C10 fluoroalkyl, or cyano. Alternatively, the term "substitution" may mean that at least one hydrogen atom in a substituent or compound is replaced by: deuterium, halogroup, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. As an example, the term "substitution" may mean that at least one hydrogen atom in a substituent or compound is replaced by one of the following: deuterium, cyano, halogen, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0029] In this specification, the term "C7~C20 aralkyl" refers to -A 101 A 102 (where A) 101 It is a C1~C14 alkylene group, and A 102 (C6-C19 aryl), for example, substituted or unsubstituted C7-C20 aryl groups may be or include substituted or unsubstituted C7-C10 aryl groups.

[0030] Unless otherwise specified in this specification, the symbol "*" indicates a portion connected to the same or different atoms or chemical formulas. Hydrogen bonds are present in the structure of the chemical formula unless specifically mentioned in the chemical formula described in this specification.

[0031] When the terms “about” or “substantially” are used with numerical values ​​in this specification, the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​within that range, such as increments of 0.1%.

[0032] Figure 1 A conceptual diagram of a rechargeable lithium battery according to an example embodiment of the present disclosure is shown for illustrative purposes. Reference Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0033] The positive electrode 10 and the negative electrode 20 may be spaced apart by a diaphragm 30 inserted therebetween. The diaphragm 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20 and the diaphragm 30 may be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20 and the diaphragm 30 may be impregnated with the electrolyte ELL.

[0034] The electrolyte ELL may be or include a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move through the separator 30 toward the positive electrode 10 or the negative electrode 20.

[0035] Positive electrode 10

[0036] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 formed on the positive electrode current collector COL1. The positive electrode active material layer AML1 includes a positive electrode active material and may further include a binder and / or a conductive material.

[0037] As an example, the positive electrode 10 may further include components that can constitute a sacrificial positive electrode.

[0038] Based on 100% by weight of the positive electrode active material layer AML1, the content of the positive electrode active material in the positive electrode active material layer AML1 can be in the range of about 90% by weight to about 99% by weight. Based on 100% by weight of the positive electrode active material layer AML1, the content of the binder and the conductive material can each be in the range of about 0.5% by weight to about 5% by weight.

[0039] The binder bonds the positive electrode active material particles together and also bonds the positive electrode active material to the positive electrode current collector COL1. Representative examples of binders include at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc., but this disclosure is not limited thereto.

[0040] Conductive materials can impart conductivity to electrodes, and any material can be used as long as it is electronically conductive and does not cause adverse chemical changes in the battery to be formed. Examples of conductive materials include carbon-based materials (such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metallic materials in the form of metal powders or metal fibers containing at least one of copper, nickel, aluminum, silver, etc.; conductive polymers (such as polyphenylene derivatives, etc.); or mixtures thereof.

[0041] Al foil can be used as the positive electrode current collector COL1, but this disclosure is not limited thereto.

[0042] Positive electrode active material

[0043] As the positive electrode active material in the positive electrode active material layer AML1, a compound capable of reversibly inserting and de-intercalating lithium (lithiation-intercalated compound) can be used. For example, at least one of the composite oxides of lithium with a metal (such as or including at least one of cobalt, manganese and nickel) can be used.

[0044] The composite oxide may be or include lithium transition metal composite oxides, and examples of such composite oxides include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, and cobalt-free nickel manganese oxides.

[0045] As an example, a compound represented by any of the following chemical formulas can be used: 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 Ni1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0≤α≤2); Li a Ni 1-b- c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0≤α≤2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0046] In the above chemical formulas, A is or includes at least one of Ni, Co, and Mn; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, and rare earth elements; D is or includes at least one of O, F, S, and P; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, and V; and L 1 It may include at least one of Mn and Al.

[0047] As an example, the positive electrode active material may be or include a high-nickel positive electrode active material, wherein the nickel content is approximately 80 mol% or more, approximately 85 mol% or more, approximately 90 mol% or more, approximately 91 mol% or more, or approximately 94 mol% or more and approximately 99 mol% or less, based on 100 mol% of metals other than lithium in the lithium transition metal composite oxide (high-nickel positive electrode active material). High-nickel positive electrode active materials can achieve high capacity and are therefore applicable to high-capacity, high-density rechargeable lithium batteries.

[0048] negative electrode 20

[0049] The negative electrode 20 for a rechargeable lithium battery includes a negative electrode current collector COL2 and a negative electrode active material layer AML2 disposed on the negative electrode current collector COL2. The negative electrode active material layer AML2 includes a negative electrode active material and may further include a binder and / or a conductive material.

[0050] For example, based on 100% by weight of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include about 90% to about 99.5% by weight of the negative electrode active material, about 0.5% to about 5% by weight of the binder, and about 0% to about 5% by weight of the conductive material.

[0051] The binder bonds the negative electrode active material particles together and also bonds the negative electrode active material to the negative electrode current collector COL2. Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used as binders.

[0052] Non-aqueous adhesives include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, and polyimide.

[0053] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol.

[0054] When the aqueous binder is used as a binder in the negative electrode active material layer AML2, the aqueous binder may further include a cellulose-based compound capable of imparting viscosity. As a cellulose-based compound, one or more types selected from carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be mixed and used. At least one of Na, K, and Li may be used as an alkali metal.

[0055] The dry binder is a fibrous polymeric material and may be or include at least one of, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyethylene oxide.

[0056] Conductive materials can impart conductivity to electrodes, and any material can be used as long as it is electronically conductive and does not cause adverse chemical changes in the battery to be formed. Examples of conductive materials include carbon-based materials (such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.); metallic materials in the form of metal powders or metal fibers containing at least one of copper, nickel, aluminum, silver, etc.; conductive polymers (such as polyphenylene derivatives, etc.); or mixtures thereof.

[0057] A current collector comprising at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, and a polymer substrate coated with a conductive metal can be used as a negative electrode current collector COL2.

[0058] Negative electrode active material

[0059] The negative electrode active material in the negative electrode active material layer AML2 includes at least one of the following: materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium-metal alloys, materials capable of doping and dedoping lithium, and transition metal oxides.

[0060] Materials capable of reversibly inserting / deintercalating lithium ions may include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Examples of crystalline carbon include graphite (such as amorphous, tabular, flake, spherical, or fibrous natural or artificial graphite), and examples of amorphous carbon include at least one of soft or hard carbon, mesophase pitch carbides, calcined coke, etc.

[0061] As an alloy of lithium and metal, lithium can be used in combination with a metal such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn.

[0062] As a material capable of doping and de-doping lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be or include silicon, a silicon-carbon composite (Si-C composite), SiO x (0 < x ≤ 2, for example, SiO2) and at least one of Si-Q alloys (where Q is or includes at least one of 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, and a rare earth element). The Sn-based negative electrode active material can be or include Sn, SnO k (0 < k ≤ 2, for example, SnO2) and at least one of Sn-based alloys.

[0063] The silicon-carbon composite can be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite can be in the form of silicon particles (Si particles) surface-coated with amorphous carbon. For example, the silicon-carbon composite can include secondary particles (cores) in which silicon primary particles are aggregated and an amorphous carbon coating (shells) provided on the surfaces of the secondary particles. Amorphous carbon can also be located between the silicon primary particles. For example, the silicon primary particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0064] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating provided on the surface of the core.

[0065] The Si-based negative electrode active material and / or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0066] Diaphragm 30

[0067] Depending on the type of the rechargeable lithium battery, a separator 30 can be present between the positive electrode 10 and the negative electrode 20. As the separator 30, at least one of a polyethylene separator, a polypropylene separator, and a polyvinylidene fluoride separator or a multilayer film of two or more layers thereof (such as at least one of a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.) can be used.

[0068] The separator 30 can include a porous substrate and a coating provided on one or both surfaces of the porous substrate, the coating including an organic material, an inorganic material, or a combination thereof.

[0069] The porous substrate may be or include a polymer membrane formed of any one of the following polymers or copolymers or mixtures thereof, or include any one of the following polymers or copolymers or mixtures thereof: such as or including at least one of polyolefins (such as polyethylene, polypropylene, etc.), polyesters (such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, glass fiber, and polytetrafluoroethylene (e.g., Teflon).

[0070] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0071] Inorganic materials may include inorganic particles, such as or including at least one of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2 and boehmite, but this disclosure is not limited thereto.

[0072] Organic and inorganic materials can exist as a mixture in a coating, or they can exist in the form of a coating that includes organic materials and a coating that includes inorganic materials laminated together.

[0073] Electrolyte ELL

[0074] Electrolytes used in rechargeable lithium batteries (ELL) consist of non-aqueous organic solvents and lithium salts.

[0075] Non-aqueous organic solvents constitute the medium through which ions participating in the electrochemical reactions in the battery can move.

[0076] The non-aqueous organic solvent may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, and aprotic solvents.

[0077] As a carbonate solvent, at least one of the following can be used: dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0078] As an ester solvent, at least one of the following can be used: methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0079] As ether solvents, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc., can be used. Cyclohexanone, etc., can be used as ketone solvents. Ethanol, isopropanol, etc., can be used as alcohol solvents. At least one of the following can be used as aprotic solvents: nitriles (such as R-CN, where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and may include double bonds, aromatic rings, or ether bonds); amides (such as dimethylformamide); dioxolane (such as 1,3-dioxolane, 1,4-dioxolane); and sulfolane.

[0080] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0081] Furthermore, when using carbonate solvents, cyclic carbonates and chain carbonates can be used in combination, and cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0082] Lithium salts are materials dissolved in non-aqueous organic solvents, thus constituting a source of lithium ions in batteries, allowing for the basic operation of rechargeable lithium batteries and facilitating the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts may include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI)), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 At least one of the following: (SO2) (where x and y are integers in the range of 1 to 20), lithium trifluoromethanesulfonate (LiSO3CF3), lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), lithium bis(oxalate)borate (LiBOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0083] Rechargeable lithium batteries

[0084] Based on the type of rechargeable lithium battery, rechargeable lithium batteries can be classified into cylindrical batteries, prismatic batteries, pouch batteries, and coin-shaped batteries. Figures 2-5 A diagram illustrating a rechargeable lithium battery according to an example embodiment is shown for illustrative purposes. Figure 2 , Figure 3 , Figure 4 and Figure 5The figures show that rechargeable lithium batteries can be cylindrical, prismatic, and pouch-type. (See reference.) Figures 2-5 The rechargeable lithium battery 100 may include an electrode assembly 40 (having a separator 30 inserted between a positive electrode 10 and a negative electrode 20) and a housing 50 therein housing the electrode assembly 40. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 configured as a sealed housing 50. Furthermore, as... Figure 3 As shown, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative electrode terminal 22 connected to the negative electrode lead connector 21. Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include Figure 5 The electrode terminals 70 explained in the text are... Figure 4 The positive electrode terminal 71 and negative electrode terminal 72, as illustrated in the diagram, form an electrical path for conducting the current generated in the electrode assembly 40 to the outside of the battery 100.

[0085] The compounds according to exemplary embodiments of the present disclosure are described in more detail below.

[0086] The compound is represented by the following chemical formula 1.

[0087] Chemical Formula 1:

[0088] .

[0089] In chemical formula 1,

[0090] R 1 and R 2 Each is independently a C1-C5 alkylene group or includes a single bond or substituted or unsubstituted alkylene groups, and

[0091] R 3 and R 4 Each of them independently comprises or includes substituted or unsubstituted C5-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C7-C20 aralkyl, substituted or unsubstituted C2-C20 alkenyl, or substituted or unsubstituted C2-C20 alkynyl.

[0092] By using this compound as an additive to the electrolyte of rechargeable lithium-ion batteries, the rate of increase in resistance and the rate of gas generation can be reduced in rechargeable lithium-ion batteries that include positive electrode active materials (e.g., high-nickel positive electrode active materials with high nickel content), and the capacity retention rate after high-temperature storage can be increased. Furthermore, by providing a low rate of increase in resistance and a high capacity retention rate at high temperatures, the battery life under high voltage and high temperature conditions can be increased. In some cases, when used as an electrolyte additive, the compound forms a film on the electrode plates, and by including sulfur in the film, the high-temperature stability of the battery can be improved, thereby increasing the battery life; however, this disclosure is not limited thereto. Here, the high voltage can be about 4.2 V or higher.

[0093] In the example, R in chemical formula 1 1 and R 2 It may be or include single bonds or methylene groups.

[0094] In the example, R in chemical formula 1 3 and R 4 Each of them may be independently or include substituted or unsubstituted C5-C10 cycloalkyl, substituted or unsubstituted C6-C10 aryl, substituted or unsubstituted C7-C10 aralkyl, substituted or unsubstituted C2-C10 alkenyl or substituted or unsubstituted C2-C10 alkynyl.

[0095] For example, the substituted or unsubstituted C5-C10 cycloalkyl group may be or include substituted or unsubstituted cyclohexyl or substituted or unsubstituted cyclopentyl.

[0096] For example, the substituted or unsubstituted C6-C10 aryl group may be or include a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group.

[0097] For example, the substituted or unsubstituted C2-C10 alkenyl group may be or include substituted or unsubstituted C2-C5 alkenyl groups, such as substituted or unsubstituted vinyl groups or substituted or unsubstituted allyl groups.

[0098] For example, the substituted or unsubstituted C2-C10 ynyl group may be or include substituted or unsubstituted C2-C5 ynyl groups, such as substituted or unsubstituted ethynyl or substituted or unsubstituted propynyl (including substituted or unsubstituted 1-propynyl, substituted or unsubstituted 2-propynyl, etc.).

[0099] In the example, the compound of chemical formula 1 may include one or more of the compounds represented by chemical formulas 1-1 to 1-7.

[0100] Chemical formula 1-1:

[0101] ,

[0102] Chemical formula 1-2:

[0103] ,

[0104] Chemical formulas 1-3:

[0105] ,

[0106] Chemical formulas 1-4:

[0107] ,

[0108] Chemical formulas 1-5:

[0109] ,

[0110] Chemical formulas 1-6:

[0111] ,

[0112] Chemical formulas 1-7:

[0113] .

[0114] Compounds of chemical formula 1 can be prepared by conventional methods known to those skilled in the art.

[0115] For example, an electrolyte for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure is described in more detail below.

[0116] An electrolyte for a rechargeable lithium battery according to an example embodiment includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes a compound of formula 1.

[0117] The electrolyte can be prepared by dissolving a lithium salt in a non-aqueous organic solvent, adding an additive of Formula 1, and then performing a mixing process. The process of mixing the electrolyte is well known in the field of electrolyte preparation, and those skilled in the art can selectively use this process as needed.

[0118] According to an example embodiment of this disclosure, the non-aqueous organic solvent may include one or more of the above-mentioned non-aqueous organic solvents.

[0119] In one embodiment, the non-aqueous organic solvent may be or comprise a mixture containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) in a volume ratio of about 10~30:10~30:40~80. Here, the volume ratio is a value based on a total volume percentage of ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) of 100%. Within the above range, the effects of the additive can be achieved, and in rechargeable lithium batteries comprising the high-nickel content positive electrode active material described below, the battery life can be further increased under high voltage and high temperature conditions.

[0120] The lithium salt according to an exemplary embodiment of this disclosure may include at least one selected from LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, Li(FSO2)2N), LiSO3CF3, LiBOB, LiDFOB, LiDFBOP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, and LiC4F9SO3. According to an exemplary embodiment, LiPF6 may be used as the lithium salt.

[0121] The concentration of the lithium salt can be in the range of about 0.1 M to about 3.0 M. For example, the concentration of the lithium salt can be about 0.5 M or higher, and can be about 1.0 M or higher. The concentration of the lithium salt can be about 3.0 M or lower, about 2.5 M or lower, or about 2.0 M or lower. In this disclosure, when the concentration of the lithium salt is in the range of about 0.1 M to about 2.0 M, the conductivity and viscosity of the electrolyte can be maintained as needed.

[0122] additive

[0123] An additive according to an example embodiment of this disclosure comprises a compound of chemical formula 1.

[0124] Compounds of Formula 1 can be included in electrolytes for rechargeable lithium batteries to provide reduced gas generation and resistance in the battery under high voltage and high temperature conditions. In particular, the additives can significantly improve the aforementioned reduction in gas generation and resistance in batteries including high-nickel positive electrode active materials with significantly high nickel content, thereby increasing battery life and stability.

[0125] Compounds of chemical formula 1

[0126] Compounds of Formula 1 are represented by the following Formula 1. Electrolytes may include one or more compounds of Formula 1.

[0127] Chemical Formula 1:

[0128] .

[0129] In chemical formula 1,

[0130] R 1 R 2 R 3 and R 4 Each is as described above.

[0131] Since chemical formula 1 has already been described above, a detailed description of chemical formula 1 will be omitted.

[0132] Based on the total amount of electrolyte, the content of the compound of Formula 1 can be in the range of about 0.05 wt% to about 5 wt%. Within this range, the effects of the above mixture can be achieved. For example, based on the total amount of electrolyte, the content of the compound of Formula 1 can be in the range of about 0.1 wt% to about 5 wt%, about 0.05 wt% to about 3 wt%, about 0.5 wt% to about 5 wt%, about 2 wt% to about 5 wt%, or about 0.1 wt% to about 2 wt%. When the content of the additive is within the above range, the effects of the above mixture can be significantly increased, and there can be an additional effect without increasing the resistance of the battery.

[0133] In the example, the content of the compound of chemical formula 1 may be about 95 wt% or more of the total additives in the electrolyte, for example, about 95 wt% to about 100 wt%, about 99 wt% to about 100 wt%, or about 100 wt%. Within the above range, battery performance can be achieved even without additional additives, thus improving battery fairness.

[0134] Accordingly, the electrolyte according to this disclosure enables rechargeable lithium batteries in which, by including additives in the combination of non-aqueous organic solvents and lithium salts, the effects of reducing resistance and reducing gas generation during high-temperature storage can be simultaneously or concurrently exhibited in rechargeable lithium batteries comprising positive electrode active materials (especially positive electrode active materials with high nickel content), thereby improving lifespan characteristics and stability.

[0135] Another exemplary embodiment of this disclosure may include a rechargeable lithium battery comprising a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, and an electrolyte, wherein the electrolyte contains a non-aqueous organic solvent, a lithium salt, and an additive, and the additive comprises a compound of formula 1.

[0136] Rechargeable lithium batteries can be used in, for example, vehicles, mobile phones and / or various types of electronic devices, and this disclosure is not limited thereto.

[0137] The positive electrode active material may be or include lithium transition metal complex oxides, and examples of such materials include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, and cobalt-free nickel manganese oxides.

[0138] As an example, a compound represented by any of the following chemical formulas can be used: 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≤); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g Gg 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).

[0139] In the above chemical formulas, A is or includes at least one of Ni, Co, and Mn; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, and rare earth elements; D is or includes at least one of O, F, S, and P; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, and V; and L 1 It may include at least one of Mn and Al.

[0140] The positive electrode active material may include at least one of the following: lithium nickel oxide represented by chemical formula 3, lithium cobalt oxide represented by chemical formula 4, lithium iron phosphate compound represented by chemical formula 5, and cobalt-free lithium nickel manganese oxide represented by chemical formula 6.

[0141] Chemical formula 3:

[0142] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 .

[0143] In chemical formula 3, 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 of the following is independently one or more of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr; and X is one or more of F, P, and S.

[0144] In chemical formula 3, 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.

[0145] Chemical formula 4:

[0146] Li a2 Co x2 M 3 y2 O2-b2 X b2 。

[0147] In Chemical Formula 4, 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 or includes one or more of 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 or includes one or more of F, P, and S.

[0148] Chemical Formula 5:

[0149] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 。

[0150] In Chemical Formula 5, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, and 0 ≤ b3 ≤ 0.1, M 4 is or includes one or more 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 or includes one or more of F, P, and S.

[0151] Chemical Formula 6:

[0152] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4 。

[0153] In Chemical Formula 6, 0.9 ≤ a4 ≤ 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 or includes one or more of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr; and X is or includes one or more of F, P, and S.

[0154] For example, the positive electrode active material may be or include a high-nickel type positive electrode active material, which has a nickel content of about 80 mol% or more, about 85 mol% or more, about 90 mol% or more, about 91 mol% or more, or about 94 mol% or more and about 99 mol% or less, based on 100 mol% of the metals other than lithium in the lithium transition metal composite oxide. The high-nickel type positive electrode active material can achieve high capacity, and thus can be applied to high-capacity and high-density rechargeable lithium batteries.

[0155] In an exemplary embodiment, the negative electrode active material may contain at least one of graphite and a Si composite.

[0156] When the negative electrode active material contains both the Si composite and graphite, the Si composite and graphite may be included in the form of a mixture. In this case, based on a total of 100 parts by weight of the Si composite and graphite, the Si composite and graphite may be included in a weight ratio within the range of about 1:99 to about 50:50. For example, the Si composite and graphite may be included in a weight ratio within the range of about 3:97 to about 20:80, about 4:96 to about 20:80, or about 5:95 to about 20:80.

[0157] The Si composite includes a core containing Si-based particles and an amorphous carbon coating. For example, the Si-based particles may include one or more of a Si-C composite, SiO x (0 < x ≤ 2, for example, SiO2) and a Si alloy. For example, the Si-C composite may include a core containing Si particles and crystalline carbon, and an amorphous carbon coating on the surface of the core. The crystalline carbon may include, for example, graphite, which may include natural graphite, artificial graphite, or a mixture thereof.

[0158] When the positive electrode contains a high-nickel type positive electrode active material having a high nickel content and the negative electrode contains graphite, the effect of improving or maximizing the high-temperature stability of the rechargeable lithium battery can be improved.

[0159] The driving voltage of the rechargeable lithium battery may be about 4.2 V or higher.

[0160] Hereinafter, examples and comparative examples of the present disclosure will be described. However, the following examples are only one exemplary embodiment of the present disclosure, and the present disclosure is not limited to the following examples.

[0161] Synthesis example 1

[0162] 10.0 g of 1,3-dicyclohexylthiourea and 50 g of tetrahydrofuran were added to a round-bottom flask and stirred at room temperature (25°C). A solution of 6.34 g of oxalyl chloride dissolved in 20 g of tetrahydrofuran was added dropwise. The temperature was then raised to 60°C, and the mixture was stirred for 12 hours. When the reaction was complete, the temperature was lowered to room temperature, and 100 g of distilled water was added. The mixture was stirred for 30 minutes. During the stirring process, a solid was formed and filtered through a filter, washed with distilled water, and then dried in a vacuum oven to obtain the compound represented by the following chemical formula 1-1 ((400 MHz, CDCl3): δ 4.63-4.55 (m, 2H), 2.21-2.11 (m, 4H), 1.88-1.69 (m, 10H), 1.38-1.18 (m, 6H)).

[0163] Chemical formula 1-1:

[0164] .

[0165] Synthesis example 2

[0166] Compounds of the following chemical formulas 1-2 ((400MHz, CDCl3): δ 7.59-7.50(m, 6H), 7.42-7.37(m, 4H)) were obtained by essentially the same method as in Synthesis Example 1, except that 1,3-diphenylthiourea was used instead of 1,3-dicyclohexylthiourea.

[0167] Chemical formula 1-2:

[0168] .

[0169] Synthesis example 3

[0170] Compounds of the following chemical formulas 1-3 ((400MHz, CDCl3): δ 7.23-7.19(m, 2H), 5.92(d, 2H, J = 17.1Hz), 5.21(d, 2H, J = 10.2Hz)) were obtained by essentially the same method as in Synthesis Example 1, except that 1,3-divinylthiourea was used instead of 1,3-dicyclohexylthiourea.

[0171] Chemical formulas 1-3:

[0172] .

[0173] Synthesis example 4

[0174] The compound of chemical formula 2 ((400MHz, CDCl3): δ 3.68 (q, 4H, J = 7.1Hz), 138 (t, 6H, J = 7.1Hz)) was obtained by essentially the same method as in Synthesis Example 1, except that 1,3-diethylthiourea was used instead of 1,3-dicyclohexylthiourea.

[0175] Chemical formula 2:

[0176] .

[0177] Examples and Comparative Examples

[0178] Example 1

[0179] (1) Preparation of electrolyte

[0180] The electrolyte was prepared by dissolving 1.0 M LiPF6 in a carbonate solvent containing ethylene carbonate: ethyl methyl carbonate: dimethyl carbonate in a volume ratio of 20:20:60 based on a total volume of 100, adding 0.1 wt% of a compound of formula 1-1 based on the total amount of electrolyte, and mixing the mixture.

[0181] (2) Preparation of rechargeable lithium batteries

[0182] The positive electrode active material slurry was prepared as follows: 97 wt% LiNi was used as the positive electrode active material. 0.91 Co 0.08 Al 0.01 O2 was mixed with 0.5 wt% artificial graphite powder, 1.0 wt% carbon black (Ketjen black) as a conductive material, and 1.5 wt% polyvinylidene fluoride (PVDF) as a binder. The mixture was then added to N-methyl-2-pyrrolidone (NMP) and stirred using a mechanical stirrer for 30 minutes. The positive electrode was prepared as follows: an aluminum current collector with a thickness of 20 µm was coated with a positive electrode active material slurry to a thickness of 60 µm using a doctor blade. The resulting material was dried in a hot air dryer at 100 °C for 0.5 hours, then dried again under vacuum at 120 °C for 4 hours, and finally rolled.

[0183] The negative electrode active material slurry was prepared as follows: 98 wt% of a negative electrode active material containing a graphite and Si composite mixed in a weight ratio of 95.8:4.2, 1 wt% of styrene-butadiene rubber (SBR), and 1 wt% of carboxymethyl cellulose (CMC) were mixed. The mixture was added to distilled water and stirred using a mechanical stirrer for 60 minutes. The negative electrode was prepared as follows: a copper current collector slurry with a thickness of 10 µm was coated to a thickness of 60 µm using a doctor blade. The resulting product was dried in a hot air dryer at 100 °C for 0.5 hours, then dried again under vacuum at 120 °C for 4 hours, and finally rolled.

[0184] A cylindrical rechargeable lithium battery was fabricated by assembling an electrode assembly consisting of a positive electrode, a negative electrode, and a separator made of polyethylene with a thickness of 16 µm, and then injecting an electrolyte into the electrode assembly.

[0185] Examples 2 to 4

[0186] The electrolyte and rechargeable lithium battery were prepared by essentially the same method as in Example 1, except that the content of the compounds of chemical formula 1-1 was changed in Table 1 below.

[0187] Example 5

[0188] The electrolyte and rechargeable lithium battery were prepared by essentially the same method as in Example 2, except that the compound of chemical formula 1-2 prepared by Synthesis Example 2 was used instead of the compound of chemical formula 1-1.

[0189] Example 6

[0190] The electrolyte and rechargeable lithium battery were prepared by essentially the same method as in Example 2, except that compounds of formula 1-3 prepared by Synthesis Example 3 were used instead of compounds of formula 1-1.

[0191] Comparative Example 1

[0192] The electrolyte and rechargeable lithium battery were prepared using essentially the same method as in Example 1, except that they did not contain compounds of chemical formula 1-1.

[0193] Comparative Example 2

[0194] The electrolyte and rechargeable lithium battery were prepared by essentially the same method as in Example 1, except that the compound of chemical formula 2 prepared by Synthesis Example 4 was used instead of the compound of chemical formula 1-1.

[0195] Evaluation Example

[0196] The following methods were used to evaluate rechargeable lithium batteries.

[0197] Evaluation Example 1: High-Temperature Storage Characteristics Evaluation (DCIR Increase Rate)

[0198] For the rechargeable lithium battery according to the embodiments and comparative examples, the ΔV / ΔI (voltage change / current change) value was measured as the initial DC internal resistance (initial DCIR). Then, the maximum energy state inside the rechargeable lithium battery was made to a fully charged state (SOC 100%). In this state, the rechargeable lithium battery was stored at 60°C for 30 days. Then, the DC internal resistance (DCIR after 30 days) was measured, and the DCIR increase rate (%) was calculated according to the following equation. The results are shown in Table 1 below.

[0199] equation:

[0200] DCIR increase rate (%) = (DCIR after 30 days / initial DCIR) × 100.

[0201] Evaluation Example 2: Capacity Retention After High-Temperature Storage

[0202] At 25°C, the rechargeable lithium batteries of the examples and comparative examples were subjected to three cycles of 0.5C CC / CV charging (4.2V, 0.05C cutoff) and 0.5C CC discharging (2.8V cutoff) to measure the discharge capacity C1 after the third cycle. The charged rechargeable lithium batteries were stored at 60°C for 30 days, then left at room temperature for 30 minutes, and subjected to 0.5C CC discharging (2.8V cutoff) to measure the discharge capacity C2. The capacity retention rate was calculated as follows and is shown in Table 1 below.

[0203] equation:

[0204] Capacity retention rate (%) = C2 / C1 × 100 (%).

[0205] Evaluation Example 3: Gas Generation Rate After High-Temperature Storage

[0206] High-temperature gas generation characteristics were evaluated for the rechargeable lithium batteries according to the embodiments and comparative examples. For this purpose, the maximum energy state inside the rechargeable lithium battery was set to a fully charged state (SOC 100%), and the amount of gas generated (in mL) was evaluated in this state, both initially (before storage at 60°C) and after 30 days of storage at 60°C. The gas generation rate was measured by measuring the volume change before and after high-temperature storage, and converted to a mass change using Archimedes' principle. The gas generation rate (%) was calculated according to the following equation and is shown in Table 1 below.

[0207] equation:

[0208] Gas generation rate (%) = (Gas generation after high-temperature storage / Gas generation before high-temperature storage) × 100.

[0209] Table 1:

[0210]

[0211] Evaluation Example 4: High Temperature (45℃) Charge / Discharge Cycle Characteristics Evaluation

[0212] High-temperature charge / discharge characteristics were evaluated for the rechargeable lithium batteries according to the embodiments and comparative examples. For this purpose, the rechargeable lithium batteries were subjected to 300 charge / discharge cycles at 45°C, 0.33 C charging (CC / CV, 4.2 V, 0.025 C cutoff) / 1.0 C discharging (CC, 2.8 V cutoff). Capacity retention was calculated according to the following equations, and the results are shown in Table 2 below.

[0213] Capacity retention (%) = (Discharge capacity after 300 cycles / Discharge capacity after 1 cycle) × 100

[0214] Evaluation Example 5: Increase in DCIR after high-temperature (45°C) charge / discharge cycles

[0215] High-temperature charge / discharge characteristics were evaluated for the rechargeable lithium batteries according to the embodiments and comparative examples. After measuring the ΔV / ΔI (voltage change / current change) value as the initial DCIR, the maximum energy state inside the rechargeable lithium battery was brought to a fully charged state (SOC 100%).

[0216] The rechargeable lithium battery was subjected to 300 charge / discharge cycles at 45°C, 0.33 C charging (CC / CV, 4.2 V, 0.025 C cutoff) / 1.0 C discharging (CC, 2.8 V cutoff), and the DCIR after 300 cycles was measured. The DCIR increase rate (%) was calculated according to the following equation, and the results are shown in Table 2 below.

[0217] DCIR increase rate (%) = (DCIR after 300 cycles / initial DCIR) × 100.

[0218] Table 2:

[0219]

[0220] Summarize

[0221] Referring to Tables 1 and 2, based on the results of Evaluation Examples 1 to 5, it can be determined that the electrolyte of the embodiments can improve the high-voltage life and high-temperature performance of rechargeable lithium batteries including high-nickel positive electrode active materials.

[0222] However, referring to Tables 1 and 2, based on the results of Evaluation Examples 1 to 5, Comparative Example 1, which does not include compounds of Chemical Formula 1 of this disclosure, and Comparative Example 2, which includes compounds of Chemical Formula 2 (including compounds other than those of Chemical Formula 1 of this disclosure), have relatively high gas generation rates. Accordingly, compared to the examples, the rechargeable lithium-ion batteries of the comparative examples containing high-nickel positive electrode active materials exhibit high DCIR increase and gas generation rates, but low capacity retention. Therefore, it can be determined that the improvements in high-voltage lifespan and high-temperature performance of the rechargeable lithium-ion batteries of the comparative examples are significantly insufficient.

[0223] When a rechargeable lithium battery is activated, the compound and electrolyte according to one example embodiment can exhibit the effect of improving life characteristics and stability under high voltage and high temperature conditions.

[0224] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and modifications may be made in any form within the scope of the claims, the detailed description of the present disclosure and the accompanying drawings, and such modifications also fall within the scope of the present disclosure.

Claims

1. A compound of chemical formula 1: Chemical Formula 1: ； In chemical formula 1, R 1 and R 2 each independently comprises a single bond or a substituted or unsubstituted C1-C5 alkylene, and R 3 and R 4 each independently includes a substituted or unsubstituted C5-C20 cycloalkyl, a substituted or unsubstituted C6-C20 aryl, a substituted or unsubstituted C7-C20 aralkyl, a substituted or unsubstituted C2-C20 alkenyl, or a substituted or unsubstituted C2-C20 alkynyl.

2. The compound of claim 1, wherein R 1 and R 2 each independently comprises a single bond or methylene.

3. The compound of claim 1, wherein R 3 and R 4 each independently includes substituted or unsubstituted C5-C10 cycloalkyl, substituted or unsubstituted C6-C10 aryl, substituted or unsubstituted C7-C10 aralkyl, substituted or unsubstituted C2-C10 alkenyl, or substituted or unsubstituted C2-C10 alkynyl.

4. The compound according to claim 1, wherein the compound of chemical formula 1 comprises one or more of the following compounds represented by chemical formulas 1-1 to 1-7: Chemical formula 1-1: ； Chemical formulas 1-2: ； Chemical formulas 1-3: ； Chemical formulas 1-4: ； Chemical formulas 1-5: ； Chemical formulas 1-6: and Chemical formulas 1-7: 。 5. An electrolyte for a rechargeable lithium battery, the electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and additive, The additives mentioned therein include the compounds according to any one of claims 1 to 4.

6. The electrolyte according to claim 5, wherein the content of the compound is in the range of 0.05wt% to 5wt% based on the total amount of the electrolyte.

7. The electrolyte according to claim 5, wherein the content of the compound is 95 wt% or more of the additive in the electrolyte.

8. The electrolyte according to claim 5, wherein the non-aqueous organic solvent is a mixture comprising ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate mixed in a volume ratio of 10-30:10-30:40-80.

9. The electrolyte according to claim 5, wherein the lithium salt comprises one or more of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, LiSO3CF3, LiBOB, LiDFOB, LiDFBOP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2 and LiC4F9SO3.

10. The electrolyte according to claim 5, wherein the concentration of the lithium salt is in the range of 0.1M to 2.0M.

11. A rechargeable lithium battery, comprising: Positive electrode, including positive electrode active material; Negative electrode, including negative electrode active material; and The electrolyte according to any one of claims 5 to 10.

12. The rechargeable lithium battery according to claim 11, wherein the positive electrode active material comprises a lithium composite oxide represented by chemical formula 3: Chemical formula 3: Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 ; In chemical formula 3, 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 of them independently includes one or more of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W and Zr, and X includes one or more of F, P and S.

13. The rechargeable lithium battery according to claim 12, wherein, In chemical formula 3, 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.

2.

14. The rechargeable lithium battery according to claim 11, wherein the negative electrode active material comprises at least one of graphite and Si composite.

15. The rechargeable lithium battery of claim 11, wherein the driving voltage of the rechargeable lithium battery is 4.2 V or higher.

16. The rechargeable lithium battery according to claim 11, wherein the rechargeable lithium battery is one of a cylindrical battery, a prismatic battery, a pouch battery, and a coin-shaped battery.

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