Electrolyte for rechargeable lithium battery and rechargeable lithium battery comprising the electrolyte

Abstract

The present disclosure relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte. The electrolyte includes a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive includes an additive of the following Chemical Formula 1, and specific details of Chemical Formula 1 are as described in the specification. Chemical Formula 1

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0179205, filed on December 5, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to 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, electric vehicles, etc.), the demand for rechargeable batteries with high energy density and high capacity (e.g., rechargeable lithium batteries) has also increased. Accordingly, improving the performance of rechargeable lithium batteries is advantageous.

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

[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 one of the relevant parameters for improving the performance of rechargeable lithium-ion batteries. Summary of the Invention

[0007] One example implementation includes an electrolyte for a rechargeable lithium battery that provides reduced resistance and reduced gas generation in rechargeable lithium batteries at high voltages and high temperatures.

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

[0009] One example embodiment includes an electrolyte for a rechargeable lithium battery, comprising a non-aqueous organic solvent, a lithium salt, and additives, wherein the additives include additives of Formula 1 (additives represented by Formula 1):

[0010] Chemical Formula 1:

[0011] .

[0012] In chemical formula 1,

[0013] R 1 R2 R 3 and R 4 Each as defined in the following description of this disclosure.

[0014] Another example embodiment includes a rechargeable lithium battery comprising: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte, wherein the electrolyte comprises the aforementioned electrolyte. Attached Figure Description

[0015] Figure 1 A conceptual diagram of a rechargeable lithium battery according to an example embodiment of the present disclosure is shown for illustrative purposes.

[0016] Figures 2-5 A diagram illustrating a rechargeable lithium battery according to an example embodiment is shown for illustrative purposes. Detailed Implementation

[0017] To fully understand the configuration and effects of this disclosure, exemplary embodiments of this 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. However, the description of these 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.

[0018] In this specification, when any component is referred to as "on" another component, it 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 refer to the same components.

[0019] Unless otherwise specified in this specification, any feature 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.

[0020] In this specification, the term "combination thereof" may refer to mixtures of components, laminates, composites, copolymers, alloys, blends, reaction products, etc.

[0021] Unless otherwise specified in this specification, the term "substitution" means that at least one hydrogen atom in a substituent or compound is replaced by one of the following: 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.

[0022] 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.

[0023] Unless otherwise specified in this specification, the symbol " "Refers to the part that is connected to the same or different atoms or chemical formulas. Unless specifically mentioned in the chemical formulas described in this specification, hydrogen is bound in the structure of the chemical formula.

[0024] When the terms “about” or “substantially” are used with numerical values ​​in this specification, it means that 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%.

[0025] 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.

[0026] The positive electrode 10 and the negative electrode 20 can be separated from each other by a diaphragm 30 inserted therebetween. The diaphragm 30 can be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20 and the diaphragm 30 can be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20 and the diaphragm 30 can be impregnated with the electrolyte ELL.

[0027] 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.

[0028] Positive electrode 10

[0029] 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.

[0030] As an example, the positive electrode 10 may further include components that can constitute a sacrificial positive electrode.

[0031] 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.

[0032] The binder bonds the positive electrode active material particles together and 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, ethylene oxide-containing polymers, 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.

[0033] Conductive materials 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.

[0034] Al foil can be used as the positive electrode current collector COL1, but this disclosure is not limited thereto.

[0035] Positive electrode active material

[0036] 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.

[0037] 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.

[0038] 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≤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 bO2 (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).

[0039] 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.

[0040] 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 greater, approximately 85 mol% or greater, approximately 90 mol% or greater, approximately 91 mol% or greater, or approximately 94 mol% or greater 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-energy-density rechargeable lithium batteries.

[0041] negative electrode 20

[0042] 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.

[0043] For example, based on 100% by weight of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include a negative electrode active material ranging from about 90% by weight to about 99.5% by weight, a binder ranging from about 0.5% by weight to about 5% by weight, and a conductive material ranging from about 0% by weight to about 5% by weight.

[0044] The binder bonds the negative electrode active material particles together and to the negative electrode current collector COL2. Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used as binders.

[0045] 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.

[0046] 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.

[0047] When an 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 of 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 the alkali metal.

[0048] The dry binder is or includes a polymeric material capable of being fibrous, and may be or include at least one of, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer and polyethylene oxide.

[0049] Conductive materials 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.

[0050] A current collector such as or including at least one of a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, and a polymer substrate coated with a conductive metal can be used as the negative electrode current collector COL2.

[0051] Negative electrode active material

[0052] The negative electrode active material in the negative electrode active material layer AML2 includes at least one of a material capable of reversibly inserting / extracting lithium ions, lithium metal, an alloy of lithium and a metal, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0053] The material capable of reversibly inserting / extracting lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon include graphite (such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite), and examples of amorphous carbon include at least one of soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0054] As the alloy of lithium and a metal, an alloy of lithium and 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 can be used.

[0055] As the material capable of doping and dedoping 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 a Si-Q alloy (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 at least one of Sn, SnO k (0 < k ≤ 2, for example, SnO2) and a Sn-based alloy.

[0056] 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 (shell) provided on the surface of the secondary particles. Amorphous carbon can also be located between the silicon primary particles, and for example, the silicon primary particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0057] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include: a core comprising crystalline carbon and silicon particles; and an amorphous carbon coating disposed on the surface of the core.

[0058] Si-based and / or Sn-based negative electrode active materials can be used in combination with carbon-based negative electrode active materials.

[0059] Diaphragm 30

[0060] Depending on the type of rechargeable lithium battery, the separator 30 may be present between the positive electrode 10 and the negative electrode 20. As the separator 30, a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer membrane of two or more layers thereof (such as or including at least one of polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / polypropylene three-layer separator, etc.) may be used.

[0061] The diaphragm 30 may include a porous substrate and a coating disposed on one or both surfaces of the porous substrate, the coating comprising an organic material, an inorganic material, or a combination thereof.

[0062] 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 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, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., Teflon).

[0063] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0064] Inorganic materials may include inorganic particles such as at least one of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2 and boehmite, or inorganic particles 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.

[0065] 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 in a laminate.

[0066] Electrolyte ELL

[0067] Electrolytes used in rechargeable lithium batteries (ELL) consist of non-aqueous organic solvents and lithium salts.

[0068] Non-aqueous organic solvents constitute the medium through which ions participating in the electrochemical reactions of the battery can move.

[0069] 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.

[0070] 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).

[0071] 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.

[0072] 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. As a protic solvent, at least one of the following can be used: 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, etc.); dioxolane (such as 1,3-dioxolane, 1,4-dioxolane, etc.); and sulfolane.

[0073] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0074] 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.

[0075] Lithium salts dissolve in non-aqueous organic solvents, thus constituting a source of lithium ions in the battery, 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 The 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) are at least one or more of the following: SO2 (where x and y are integers in the range of 1 to 20), lithium trifluoromethanesulfonate (LiSO3CF3), lithium tetrafluoromethanesulfonate (LiDFSI), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0076] Rechargeable lithium batteries

[0077] Rechargeable lithium batteries can be classified according to their type as 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. (See also...) Figure 2 , Figure 3 , Figure 4 and Figure 5 The figures show that rechargeable lithium batteries can be cylindrical, prismatic, and pouch-type. (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 4The 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.

[0078] The electrolyte of a rechargeable lithium battery according to an example embodiment of the present disclosure is described in more detail below.

[0079] An electrolyte for a rechargeable lithium battery according to an example embodiment includes the above-described non-aqueous organic solvent, lithium salt, and additives, wherein the additives include additives of chemical formula 1 described below.

[0080] Electrolytes can be prepared by dissolving lithium salts in a non-aqueous organic solvent, adding an additive of Formula 1, and then mixing. The process of mixing electrolytes is widely known in the field of electrolyte preparation, and those skilled in the art can select and use the mixing process as desired.

[0081] According to an example embodiment of this disclosure, the non-aqueous organic solvent may include one or more of the above-described non-aqueous organic solvents.

[0082] In one example embodiment, the non-aqueous organic solvent may be or include a mixture of ethylene carbonate (EC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) comprising a volume ratio in the range of about 10~40:10~40:40~80 or 10~30:10~30:40~80. Here, the volume ratio is based on the sum of 100 volume% of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). Within the above range, the effects of the additives described below can be achieved, and the battery life can be further improved under high voltage and high temperature conditions in rechargeable lithium batteries comprising the positive electrode active material with high nickel content described below.

[0083] According to an exemplary embodiment of this disclosure, the lithium salt may include at least one or more of LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide (Li(FSO2)2N, LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), LiSO3CF3, LiBOB, LiDFOB, LiDFBOP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, and LiC4F9SO3. In one exemplary embodiment, LiPF6 may be used as the lithium salt.

[0084] 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 in the following ranges: about 0.5 M or more, or about 1.0 M or more. The concentration of the lithium salt can be in the range of about 3.0 M or less, about 2.5 M or less, or about 2.0 M or less. 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.

[0085] additive

[0086] An additive according to an example embodiment of this disclosure includes an additive of chemical formula 1 as described below.

[0087] By being included in the electrolyte of a rechargeable lithium-ion battery, the additive of Formula 1 can provide the effect of reducing gas generation and resistance in the battery under high voltage and high temperature conditions. In particular, the additive can improve battery life and safety by significantly improving the effect of reducing gas generation and lowering resistance in batteries that include positive electrode active materials with significantly high nickel content. Batteries that include positive electrode active materials with significantly high nickel content have high energy density, but their performance can degrade when stored at high voltage and high temperature due to increased gas generation and resistance. Here, "high voltage" means approximately 4.4 V or higher.

[0088] Additives of Chemical Formula 1 are represented by the following Chemical Formula 1. The electrolyte may include one or more additives represented by the following Chemical Formula 1:

[0089] Chemical Formula 1:

[0090] .

[0091] In chemical formula 1,

[0092] R 1 and R 2 Each of these elements independently comprises or includes hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl.

[0093] R 3 and R 4Each of these elements independently comprises or includes hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl; or is represented by the following chemical formula 1-1.

[0094] R 3 and R 4 At least one of them is represented by the following chemical formula 1-1:

[0095] Chemical formula 1-1:

[0096] .

[0097] In chemical formula 1-1,

[0098] R 5 and R 6 Each of these elements independently comprises or includes a single bond, a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 ynynyl group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group. Refers to the part that connects to N in chemical formula 1.

[0099] In one example implementation, R in Formula 1 3 and R 4 Both can be represented by chemical formula 1-1. In this case, when applied to batteries containing positive electrode active materials with high nickel content, the additive of chemical formula 1 can have the desired or improved effect of improving battery life at high voltage and high temperature.

[0100] In one example implementation, in chemical formula 1-1, R 5 and R 6 Each of the additives may independently be or include substituted or unsubstituted C1-C20 alkylene groups, such as substituted or unsubstituted C1-C10 alkylene groups or substituted or unsubstituted C1-C5 alkylene groups, such as substituted or unsubstituted methylene, substituted or unsubstituted ethylene, substituted or unsubstituted linear or branched propylene, substituted or unsubstituted linear or branched butylene, or substituted or unsubstituted linear or branched pentylene. In this case, when applied to batteries comprising positive electrode active materials with high nickel content, the additive of Formula 1 may have the desired or improved effect of improving battery life at high voltage and high temperature.

[0101] R 1 and R 2 Each of the additives may independently be or include hydrogen or substituted or unsubstituted C1-C20 alkyl groups, such as substituted or unsubstituted C1-C10 alkyl groups or substituted or unsubstituted C1-C5 alkyl groups, such as hydrogen, substituted or unsubstituted methyl groups, substituted or unsubstituted ethyl groups, substituted or unsubstituted straight-chain or branched propyl groups, substituted or unsubstituted straight-chain or branched butyl groups, or substituted or unsubstituted straight-chain or branched pentyl groups. In this case, when applied to batteries comprising positive electrode active materials with high nickel content, the additive of Formula 1 may have the desired or improved effect of improving battery life at high voltage and high temperature.

[0102] According to another exemplary embodiment of this disclosure, the additive of chemical formula 1 may be one or more additives represented by the following chemical formulas 1-3:

[0103] Chemical formulas 1-3:

[0104] .

[0105] In chemical formulas 1-3,

[0106] R 1 and R 2 Each independently constitutes or includes those as defined in Chemical Formula 1, and

[0107] R 7 and R 8 Each of these elements independently comprises or includes substituted or unsubstituted C1-C20 alkylene, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkylene, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl.

[0108] In one example implementation, in chemical formulas 1-3, R 7 and R 8Each of the additives may independently be or include substituted or unsubstituted C1-C20 alkylene groups, such as substituted or unsubstituted C1-C10 alkylene groups or substituted or unsubstituted C1-C5 alkylene groups, such as substituted or unsubstituted methylene, substituted or unsubstituted ethylene, substituted or unsubstituted linear or branched propylene, substituted or unsubstituted linear or branched butylene, or substituted or unsubstituted linear or branched pentylene. In this case, when applied to batteries comprising positive electrode active materials with high nickel content, the additive of Formula 1 may have the desired or improved effect of improving battery life at high voltage and high temperature.

[0109] In one example embodiment, the additive of chemical formula 1 may include one or more of the additives represented by chemical formulas 1-4 to 1-10:

[0110] Chemical formulas 1-4:

[0111] .

[0112] Chemical formulas 1-5:

[0113] .

[0114] Chemical formulas 1-6:

[0115] .

[0116] Chemical formulas 1-7:

[0117] .

[0118] Chemical formulas 1-8:

[0119] .

[0120] Chemical formulas 1-9:

[0121] .

[0122] Chemical formulas 1-10:

[0123] .

[0124] The additives of Formula 1 and the additives of Formulas 1-3 can each be synthesized by conventional synthetic methods known to those skilled in the art. For example, additives can be prepared using compounds providing 4H-1,2,4-triazolyl and CN- groups.

[0125] Based on the total amount of the electrolyte, the additive of Formula 1 can be included in an amount ranging from about 0.05 wt% to about 5 wt%. Within this range, the effects of the mixture described above can be achieved. For example, based on the total amount of the electrolyte, the additive of Formula 1 can be included in an amount ranging from about 0.1 wt% to about 5 wt%, about 0.05 wt% to about 5 wt%, or about 0.5 wt% to about 5 wt%. When the content of the additive of Formula 1 is within the above range, the effect of the mixture is significantly increased, and there may be an additional effect without increasing the battery resistance.

[0126] In one example embodiment, the additive of Formula 1 may be included in an amount of about 95 wt% or more (e.g., in the range of about 95 wt% to about 100 wt%, 99 wt% to 100 wt%, or 100 wt%) of the total additives in the electrolyte. Within the above range, the processability of the battery can be improved while achieving battery performance, even without additional additives.

[0127] As a result, by including additives in the combination of non-aqueous organic solvents and lithium salts, the electrolyte according to this disclosure, in a rechargeable lithium battery including a positive electrode active material (particularly a positive electrode active material with a high nickel content), simultaneously or concurrently produces the effect of reducing resistance increase and gas generation during high-temperature storage, thereby ensuring the realization of a rechargeable lithium battery with improved life characteristics and stability.

[0128] In another exemplary embodiment of this disclosure, a rechargeable lithium battery may be provided, comprising: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte, wherein the electrolyte comprises a non-aqueous organic solvent, a lithium salt, and an additive, and the additive comprises an additive of Formula 1.

[0129] Rechargeable lithium batteries can be used in, for example, vehicles, mobile phones and / or various types of electronic devices, but this disclosure is not limited thereto.

[0130] The positive electrode active material may be or include lithium transition metal composite oxides, and examples may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds and cobalt-free nickel manganese oxides.

[0131] 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 bO 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0≤α≤2); Li a Ni 1-b- c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0≤α≤2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8)

[0132] 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 1It is or includes at least one of Mn and at least one of Al.

[0133] The positive electrode active material may include at least one of the following: lithium nickel oxide represented by chemical formula 2, lithium cobalt oxide represented by chemical formula 3, lithium iron phosphate compound represented by chemical formula 4, and cobalt-free lithium nickel manganese oxide represented by chemical formula 5.

[0134] Chemical formula 2:

[0135] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 .

[0136] In chemical formula 2, 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, and M 1 and M 2 Each of the elements 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, Y, and Zr, and X is or includes one or more of F, P, and S.

[0137] In chemical formula 2, 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.

[0138] Chemical formula 3:

[0139] Li a2 Co x2 M 3 y2 O 2-b2 X b2 .

[0140] In chemical formula 3, 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 X is or includes at least 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 at least one or more of F, P, and S.

[0141] Chemical formula 4:

[0142] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 。

[0143] In Chemical Formula 4, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, 0.9 ≤ x3 + y3 ≤ 1.1, and 0 ≤ b3 ≤ 0.1, and M 4 is or includes at least 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 at least one or more of F, P, and S.

[0144] Chemical Formula 5:

[0145] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4 。

[0146] In Chemical Formula 5, 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, and M 5 is or includes at least one or more of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, Y, and Zr, and X is or includes at least one or more of F, P, and S.

[0147] For example, the positive electrode active material may be or include a high-nickel positive electrode active material, wherein based on 100 mol% of the metals other than lithium in the lithium transition metal composite oxide, the nickel content is about 80 mol% or greater, about 85 mol% or greater, about 90 mol% or greater, about 91 mol% or greater, or about 94 mol% or greater and about 99 mol% or less. The high-nickel positive electrode active material can achieve a high capacity and thus can be applied to a high-capacity, high-energy density rechargeable lithium battery.

[0148] In an exemplary embodiment, the negative electrode active material may include at least one of graphite and a Si composite.

[0149] When the negative electrode active material includes both a Si composite and graphite, the Si composite and graphite may be included in the form of a mixture, and in this case, based on a total of 100 parts by weight of the Si composite and graphite, the weights of the included Si composite and graphite may be in the range of about 1:99 to about 50:50. For example, the weights of the included Si composite and graphite may be in the range of about 3:97 to about 20:80, in the range of about 4:96 to about 20:80, or in the range of about 5:95 to about 20:80.

[0150] The Si composite includes a core containing Si-based particles and an amorphous carbon coating, and 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 including Si particles and crystalline carbon, and an amorphous carbon coating located on the surface of the core. The crystalline carbon may include, for example, graphite (and for example, natural graphite, artificial graphite, or a mixture thereof).

[0151] When the positive electrode includes a high-nickel positive electrode active material and the negative electrode includes graphite, the effect of improving the high-temperature stability of the rechargeable lithium battery can be maximized.

[0152] Hereinafter, examples and comparative examples of the present disclosure are described. However, the following examples are only examples of the present disclosure, and the present disclosure is not limited to the following examples.

[0153] Synthesis example 1

[0154] Put 8 g of NaOH into a round-bottom flask, then put 50 g of distilled water, and stir for 30 minutes at room temperature (23 ± 2°C).

[0155] Put 8.41 g of 4-amino-1,2,4-triazole into it, stir for another 30 minutes, and then keep the temperature inside the reaction mixture not exceeding 40°C while slowly adding 13.3 g of acrylonitrile dropwise to the reaction mixture.

[0156] When a white solid is produced, filter the white solid through a filter, wash it with water and ethanol, and then dry it under vacuum to obtain a compound (additive) represented by Chemical Formula 1-4 below.

[0157] (400 MHz, DMSO-d6): δ 8.74 (s, 2H), 3.40 - 3.37 (m, 4H), 2.53 - 2.49 (m, 4H)

[0158] Chemical Formula 1-4:

[0159] .

[0160] Synthesis example 2

[0161] The compounds represented by the following chemical formulas 1-5 were obtained by performing essentially the same process as in Synthesis Example 1, except that 4-amino-3,5-dimethyl-4H-1,2,4-triazole was used instead of 4-amino-1,2,4-triazole.

[0162] Chemical formulas 1-5:

[0163] .

[0164] Synthesis example 3

[0165] The compounds represented by the following chemical formulas 1-6 were obtained by performing essentially the same process as in Synthesis Example 1, except that 4-amino-1,2,4-triazole was used instead of 4-amino-1,2,4-triazole and allyl cyanide was used instead of acrylonitrile.

[0166] Chemical formulas 1-6:

[0167] .

[0168] Examples and Comparative Examples

[0169] Example 1

[0170] (1) Preparation of electrolyte

[0171] 1.25 M LiPF6 was dissolved in a carbonate solvent comprising ethylene carbonate: methyl ethyl carbonate: dimethyl carbonate in a volume ratio of 20:30:50 based on 100% of the total volume, and additives of formulas 1-4 were added and mixed to prepare an electrolyte.

[0172] (2) Preparation of rechargeable lithium batteries

[0173] Based on the total weight of the positive electrode active material layer, 97 wt% of LiNi was used as the positive electrode active material. 0.91 Co 0.08 Al 0.01O2, 0.5 wt% artificial graphite powder as a conductive material, 1 wt% carbon black (Ketjen black) as a conductive material, and 1.5 wt% polyvinylidene fluoride (PVDF) as a binder were mixed and placed in N-methyl-2-pyrrolidone (NMP) and stirred for 30 minutes using a mechanical stirrer to prepare a positive electrode active material slurry. The positive electrode active material slurry was coated onto a 20 μm thick aluminum current collector using a doctor blade to a thickness of approximately 60 μm, dried in a hot air dryer at 100°C for 0.5 hours, and then dried under vacuum at 120°C for 4 hours. Finally, it was rolled to prepare the positive electrode.

[0174] Based on the total weight of the negative electrode active material layer, 98 wt% of a mixture of graphite and Si composites 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 then placed in distilled water and stirred using a mechanical stirrer for 60 minutes to prepare a negative electrode active material slurry. The slurry was coated onto a 10 μm thick copper current collector using a doctor blade to a thickness of approximately 60 μm. It was dried in a hot air dryer at 100°C for 0.5 hours, followed by further drying under vacuum at 120°C for 4 hours, and then rolled to prepare the negative electrode.

[0175] A positive electrode, a negative electrode, and a separator made of polyethylene material with a thickness of 16 μm were assembled to prepare an electrode assembly, and an electrolyte was injected to prepare a cylindrical rechargeable lithium battery.

[0176] Examples 2 to 4

[0177] The electrolyte and battery were prepared in essentially the same manner as in Example 1, except that the contents of the additives of chemical formulas 1-4 in Example 1 were varied as shown in Table 1 below.

[0178] Example 5

[0179] The electrolyte and battery were prepared in essentially the same manner as in Example 2, except that additives of chemical formulas 1-5 were used instead of additives of chemical formulas 1-4.

[0180] Example 6

[0181] The electrolyte and battery were prepared in essentially the same manner as in Example 2, except that additives of chemical formulas 1-6 were used instead of additives of chemical formulas 1-4.

[0182] Comparative Example 1

[0183] The electrolyte and battery were prepared in essentially the same manner as in Example 1, except that the additives of chemical formulas 1-4 in Example 1 were not used.

[0184] Evaluation Example

[0185] Use the following methods to evaluate rechargeable lithium batteries.

[0186] Evaluation Example 1: High-Temperature Storage Characteristics - Evaluation of Cell Thickness Increase Rate

[0187] The high-temperature gas generation characteristics were evaluated by measuring the cell thickness increase rate of the rechargeable lithium batteries according to the embodiments and comparative examples. The initial thickness of the cell (the thickness of the cell on day 0) and the thickness of the cell after storage at 60°C for 28 days (the thickness of the cell on day 28) were measured, and the thickness increase rate was calculated. The results are shown in Table 1 below. The thickness increase rate was calculated according to the following equation.

[0188] equation:

[0189] Thickness increase rate (%) = [thickness of the battery cell after 28 days of storage at 60°C / initial thickness of the battery cell] × 100.

[0190] For example, the thickness of a battery cell is measured using an extrusion thickness gauge from Mitutoyo by placing the battery cell between extrusion plates and extruding it with a weight of 300 g.

[0191] Evaluation Example 2: Evaluation of High Temperature Storage Characteristics - OCV Retention Rate

[0192] For the rechargeable lithium batteries according to the examples and comparative examples, the initial OCV (OCV on day 0) was measured after charging at 0.5C CC / CV (4.4V 0.05C cutoff). The batteries were then stored at 60°C for 28 days, after which the OCV (OCV on day 28) was measured, and δOCV (ΔOCV) was calculated (i.e., ΔOCV = OCV on day 0 - OCV on day 28). The results are shown in Table 1 below. A smaller ΔOCV value indicates better capacity retention.

[0193] Evaluation Example 3: Evaluation of High-Temperature Storage Characteristics - DCIR Increase Rate

[0194] 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) (DCIR on day 0), and then the maximum energy state inside the battery was made to a fully charged state (SOC 100%). In this state, the battery was stored at a high temperature (60°C) for 60 days, and then the DCIR was measured (DCIR after 60 days or DCIR on day 60). The DCIR increase rate (%) was calculated according to the following equation, and the results are shown in Table 2 below.

[0195] equation:

[0196] DCIR increase rate (%) = (DCIR after 60 days / initial DCIR) × 100.

[0197] The results of evaluation examples 1 to 3 above are shown in Table 1 below.

[0198] Table 1:

[0199]

[0200] (Continued from Table 1)

[0201]

[0202] In Table 1, the weight percentage of additives represents the relative weight of the additives to the total amount of 100% electrolyte.

[0203] in conclusion

[0204] Referring to Table 1 above, based on the results of Evaluation Examples 1 to 3, it can be concluded that the electrolyte of the embodiments can improve high-voltage life and high-temperature performance in rechargeable lithium batteries including high-nickel positive electrode active materials.

[0205] However, referring to Table 1 above, based on the results of Evaluation Examples 1 to 3, Comparative Example 1, which does not include the additive of Chemical Formula 1 of this disclosure, has a relatively high gas generation amount. Therefore, compared with the examples, in the rechargeable lithium battery of the comparative example including the high-nickel positive electrode active material, the cell thickness increase rate is high, resulting in a high gas generation amount, a high OCV reduction rate, and a high DCIR increase rate. It is expected that there will be a significant lack of improvement in high-voltage life and high-temperature performance.

[0206] After the rechargeable lithium battery is activated, the electrolyte according to an example embodiment can exhibit improved life characteristics and stability in the rechargeable lithium battery under high voltage and high temperature conditions.

[0207] Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and various modifications may be made within the scope of the claims, the detailed description of the present disclosure, and the accompanying drawings, which also fall within the scope of the present disclosure.

Claims

1. An electrolyte for a rechargeable lithium battery, the electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and additive, The additives mentioned above include additives represented by chemical formula 1: Chemical Formula 1: ； In chemical formula 1, R 1 and R 2 Each independently comprises hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl, and R 3 and R 4 Each of these elements independently comprises hydrogen, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl; or is represented by the following chemical formula 1-1. R 3 and R 4 At least one of them is represented by the following chemical formula 1-1: Chemical formula 1-1: ； In chemical formula 1-1, R 5 and R 6 Each independently comprises a single bond, a substituted or unsubstituted C1-C20 alkylene group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 ynynyl group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group, and Refers to the part that connects to N in chemical formula 1.

2. The electrolyte of claim 1, wherein the additive represented by chemical formula 1 is represented by chemical formulas 1-3: Chemical formulas 1-3: ； In chemical formulas 1-3, R 1 and R 2 Each is independently identical to that in chemical formula 1, and R 7 and R 8 Each of these independently includes substituted or unsubstituted C1-C20 alkylene, substituted or unsubstituted C1-C20 alkoxy, substituted or unsubstituted C2-C20 alkenyl, substituted or unsubstituted C2-C20 alkynyl, substituted or unsubstituted C3-C20 cycloalkylene, substituted or unsubstituted C6-C20 aryl, or substituted or unsubstituted C2-C20 heteroaryl.

3. The electrolyte of claim 1, wherein the additive represented by chemical formula 1 comprises one or more additives represented by chemical formulas 1-4 to 1-10: Chemical formulas 1-4: ； Chemical formulas 1-5: ； Chemical formulas 1-6: ； Chemical formulas 1-7: ； Chemical formulas 1-8: ； Chemical formulas 1-9: ； Chemical formulas 1-10: 。 4. The electrolyte of claim 1, wherein the additive represented by chemical formula 1 is included in an amount ranging from 0.05 wt% to 5 wt% based on the total amount of the electrolyte.

5. The electrolyte of claim 1, wherein the additive represented by chemical formula 1 is included in an amount of 95 wt% or greater of the total additives of the electrolyte.

6. The electrolyte of claim 1, wherein the non-aqueous organic solvent comprises a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate in a volume ratio in the range of 10-40:10-40:40-80.

7. The electrolyte of claim 1, wherein the lithium salt comprises LiPF6, LiClO4, LiBF4, lithium bis(fluorosulfonyl)imide, LiTFSI, LiSO3CF3, LiBOB, LiDFOB, LiDFBOP, LiTFOP, LiPO2F2, LiSbF6, LiAsF6, LiAlO2, LiAlCl4, LiCl, LiI, LiN(SO3C2F5)2, LiN(C x F 2x+1 SO2)(C y F 2y+1 One or more of SO2 and LiC4F9SO3, wherein x and y are integers in the range of 1 to 20.

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

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

10. The rechargeable lithium battery of claim 9, wherein the positive electrode active material comprises a lithium transition metal composite oxide having a nickel content of 80 mol% or greater based on 100 mol% of metals other than lithium in the lithium transition metal composite oxide.

11. The rechargeable lithium battery of claim 9, wherein the positive electrode active material comprises a lithium transition metal composite oxide, and the lithium transition metal composite oxide comprises a lithium composite oxide represented by the following chemical formula 2: Chemical formula 2: Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 ; in: 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, and M 1 and M 2 Each 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.

12. The rechargeable lithium battery of claim 11, wherein in chemical formula 2, 0.8 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.2, and 0 ≤ z1 ≤ 0.

2.

13. The rechargeable lithium battery of claim 9, wherein the negative electrode active material comprises at least one of graphite and Si composite.

14. The rechargeable lithium battery of claim 9, wherein the rechargeable lithium battery is a cylindrical battery, a prismatic battery, a pouch battery, or a coin-shaped battery.

Images