Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention discloses an electrolyte and a rechargeable lithium battery including the same. The electrolyte comprises a non-aqueous organic solvent, a lithium salt and an additive. The additive includes a compound 1 represented by Chemical Formula 1 and a compound 2 represented by Chemical Formula 2. [Chemical Formula 1] # imgabs0 # [Chemical Formula 2] # imgabs1 #

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2023 - 0189555, filed with the Korean Intellectual Property Office on December 22, 2023, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. Background art

[0004] Recently, with the rapid popularization of electronic devices (such as mobile phones, laptop computers) and / or electric vehicles that utilize batteries (e.g., operate using batteries), the demand or expectation for rechargeable lithium batteries with relatively high energy density and relatively high capacity has increased rapidly. Accordingly, in - depth research has been conducted to improve the characteristics of rechargeable lithium batteries.

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte, wherein each of the positive electrode and the negative electrode includes an active material capable of intercalating and de - intercalating lithium ions, and when lithium ions are intercalated and de - intercalated (e.g., when), electrical energy is generated through oxidation and reduction reactions.

[0006] A lithium salt dissolved in a non - aqueous organic solvent is used as the electrolyte of a rechargeable lithium battery. The characteristics of a rechargeable lithium battery are exhibited through complex reactions between the positive electrode and the electrolyte and between the negative electrode and the electrolyte. Accordingly, using a suitable or appropriate electrolyte is one of the important variables for improving rechargeable lithium batteries. Summary of the invention

[0007] Aspects according to some embodiments relate to an electrolyte for a rechargeable lithium battery having improved stability and life characteristics at relatively high temperatures.

[0008] Aspects according to some embodiments relate to a rechargeable lithium battery including the electrolyte discussed above.

[0009] Additional aspects will be set forth in part in the following description and in part will be obvious from the description, or may be learned by practice of the presented embodiments of the present disclosure.

[0010] According to one or more embodiments of the present disclosure, an electrolyte for a rechargeable lithium battery may include: a non - aqueous organic solvent; a lithium salt; and an additive. The additive may include Compound 1 represented by Chemical Formula 1 and Compound 2 represented by Chemical Formula 2.

[0011] [Chemical Formula 1]

[0012]

[0013] [Chemical Formula 2]

[0014]

[0015] In Chemical Formula 1, R1 to R4 may each independently be a hydrogen atom (i.e., may be hydrogen or H), a halogen atom, or a substituted or unsubstituted C1-C5 alkyl group.

[0016] According to one or more embodiments of the present disclosure, a rechargeable lithium battery may include: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and an electrolyte as discussed above. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrating embodiments of the present disclosure and the description together are used to explain the principles of the present disclosure. In the drawings,

[0018] Figure 1 a simplified conceptual diagram showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0019] Figure 2 is a schematic illustration of a cylindrical battery according to some embodiments.

[0020] Figure 3 is a schematic illustration of a prismatic battery according to some embodiments.

[0021] Figure 4 is a schematic illustration of a pouch-type or pouch-like battery according to some embodiments.

[0022] Figure 5 is a schematic illustration of a pouch-type or pouch-like battery according to some embodiments. DETAILED DESCRIPTION

[0023] To fully understand the configuration and effects of the present disclosure, one or more embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be noted that the present disclosure is not limited to the following exemplary embodiments, and may be implemented in one or more suitable forms. Instead, the exemplary embodiments are provided only to enable those skilled in the art to fully understand the scope of the present disclosure.

[0024] In this description, it will be understood that if, for example, when an element is referred to as being on another element, the element can be directly on the other element or there can be intervening elements between them. In the drawings, for the purpose of effectively explaining the technical content, the dimensions (e.g., thickness) of some components are enlarged. The same reference numerals refer to the same elements throughout, and their repeated description may not be provided in the specification.

[0025] Unless otherwise specifically stated in this description, the singular forms of expressions may include the plural forms. Additionally, unless otherwise specifically stated, the phrase “A or B” may indicate “A but not B”, “B but not A”, and “A and B”. The terms “comprises / includes” and / or “comprising / including” used in this description do not exclude the presence or addition of one or more other components.

[0026] In this description, the term “a combination thereof” may refer to a mixture, stack, composite, copolymer, alloy, blend, or reaction product of components.

[0027] In this description, unless otherwise individually defined, the term “substituted” may mean that at least one hydrogen of a substituent or compound is substituted by the following: deuterium, a halogen group, a hydroxyl group, an amino group, a C1 - C30 amino group, a nitro group, a C1 - C40 silyl group, a C1 - C30 alkyl group, a C1 - C10 alkylsilyl group, a C6 - C30 arylsilyl group, a C3 - C30 cycloalkyl group, a C3 - C30 heterocycloalkyl group, a C6 - C30 aryl group, a C2 - C30 heteroaryl group, a C1 - C20 alkoxy group, a C1 - C10 fluoroalkyl group, a cyano group, and / or a combination thereof (e.g., any suitable combination).

[0028] For example, the term “substituted” may mean that at least one hydrogen of a substituent or compound is substituted by the following: deuterium, a halogen group, a C1 - C30 alkyl group, a C1 - C10 alkylsilyl group, a C6 - C30 arylsilyl group, a C3 - C30 cycloalkyl group, a C3 - C30 heterocycloalkyl group, a C6 - C30 aryl group, a C2 - C30 heteroaryl group, a C1 - C10 fluoroalkyl group, or a cyano group. For example, the term “substituted” may mean that at least one hydrogen of a substituent or compound is substituted by deuterium, a halogen group, a C1 - C20 alkyl group, a C6 - C30 aryl group, a C1 - C10 fluoroalkyl group, or a cyano group. In one or more embodiments, the term “substituted” may mean that at least one hydrogen of a substituent or compound is substituted by deuterium, a halogen group, a C1 - C5 alkyl group, a C6 - C18 aryl group, a C1 - C5 fluoroalkyl group, or a cyano group. For example, the term “substituted” may mean that at least one hydrogen of a substituent or compound is substituted by deuterium, a cyano group, a halogen group, a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, a biphenyl group, a terphenyl group, a trifluoromethyl group, or a naphthyl group.

[0029] Figure 1Illustrates a simplified conceptual diagram of a rechargeable lithium battery showing one or more embodiments according to the present disclosure. Refer to Figure 1 , the rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0030] The positive electrode 10 and the negative electrode 20 may be spaced apart and / or separated (e.g., spaced or separated) across the separator 30. The separator 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be in contact with the electrolyte ELL. For example, the positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated in the electrolyte ELL.

[0031] The electrolyte ELL may be a medium for the transfer of lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions may move through the separator 30 toward one of the positive electrode 10 and the negative electrode 20.

[0032] Positive electrode 10

[0033] 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 may include positive electrode active material and may further include a binder and / or a conductive material.

[0034] In some embodiments, the positive electrode 10 may further include an additive that can be used as a sacrificial positive electrode.

[0035] Based on 100 wt% of the positive electrode active material layer AML1, the amount of the positive electrode active material may range from about 90 wt% to about 99 wt%. Based on 100 wt% of the positive electrode active material layer AML1, the amounts of the binder and the conductive material may each be from about 0.5 wt% to about 5 wt%.

[0036] The binder may be used to improve the attachment of the positive electrode active material particles to each other and also to improve the attachment of the positive electrode active material to the positive electrode current collector COL1. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylate esterified styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, or nylon, but the present disclosure is not limited thereto.

[0037] A conductive material (e.g., an electronic conductor) can be used to provide electrode conductivity, and any suitable conductive material that does not cause chemical changes in the battery can be used as the conductive material constituting the battery. The conductive material can include, for example: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube; metal powders or metal fibers including one or more of copper (Cu), nickel (Ni), aluminum (Al), and silver (Ag); conductive polymers such as polyphenylene derivatives; and / or a mixture thereof (e.g., any suitable mixture).

[0038] In some embodiments, an Al foil can be used as the positive electrode current collector COL1, but the present disclosure is not limited thereto.

[0039] Positive electrode active material

[0040] The positive electrode active material in the positive electrode active material layer AML1 can include: a compound that can reversibly intercalate and deintercalate lithium (e.g., a lithiated intercalation compound). For example, the positive electrode active material can include: at least one type of composite oxide including lithium and a metal selected from cobalt (Co), manganese (Mn), nickel (Ni), and / or a combination thereof (e.g., any suitable combination).

[0041] The composite oxide can include a lithium transition metal composite oxide, for example, a lithium nickel-based oxide (e.g., a nickel cobalt aluminum (NCA)-based lithium composite oxide (e.g., LiNiCoAlO2)), a lithium cobalt-based oxide, a lithium manganese-based oxide, a lithium iron (Fe) phosphate (P) compound, a cobalt-free nickel manganese-based oxide, and / or a combination thereof (e.g., any suitable combination).

[0042] For example, the positive electrode active material can include a compound represented by one of the following chemical formulas (e.g., selected from one of the following chemical formulas). Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05), Li a Mn 2-b X b O 4- c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05), Li a Ni 1-b-c Co b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2), Lia 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) / or Li a FePO4(0.90 ≤ a ≤ 1.8).

[0043] In the above chemical formulas, A is Ni, Co, Mn, and / or a combination thereof (e.g., any suitable combination), X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare elements, and / or a combination thereof (e.g., any suitable combination), D is O, F, S, P, and / or a combination thereof (e.g., any suitable combination), G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and / or a combination thereof (e.g., any suitable combination), and L 1 is Mn, Al, and / or a combination thereof (e.g., any suitable combination).

[0044] For example, based on 100 mol% of the metals in the lithium transition metal composite oxide excluding lithium (lithium not included in the calculation), the positive electrode active material can be a high-nickel type positive electrode active material with a nickel content (e.g., amount) equal to or greater than about 80 mol%, equal to or greater than about 85 mol%, equal to or greater than about 90 mol%, equal to or greater than about 91 mol% or equal to or greater than about 94 mol% and equal to or less than about 99 mol%. The high-nickel type positive electrode active material can achieve high capacity, and thus can be applied to rechargeable lithium batteries with high capacity and high energy density.

[0045] Negative electrode 20

[0046] The negative electrode 20 for a rechargeable lithium battery may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 located on the negative electrode current collector COL2. The negative electrode active material layer AML2 may include a negative electrode active material, and may further include a binder and / or a conductive material.

[0047] For example, (based on 100 wt% of the negative electrode active material layer AML2), the negative electrode active material layer AML2 may include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0048] The binder can be used to improve the attachment between the negative electrode active material particles to each other, and also to improve the attachment between the negative electrode active material and the negative electrode current collector COL2. The binder may include a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination thereof (e.g., any suitable combination).

[0049] The non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, and / or a combination thereof (e.g., any suitable combination).

[0050] The aqueous binder may include styrene-butadiene rubber, (meth)acrylate esterified styrene-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, epichlorohydrin rubber, polyphosphazene, poly(meth)acrylonitrile, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and / or a combination thereof (e.g., any suitable combination).

[0051] If (e.g., when) an aqueous binder is used as the binder in the negative electrode active material layer AML2, a cellulose compound capable of providing an appropriate viscosity may be further included. The cellulose compound may include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts. The alkali metal may include Na, K, and / or Li.

[0052] The dry binder may include a polymer material that can fibrillate (e.g., capable of forming into a fibrous form) such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride - hexafluoropropylene copolymer, polyethylene oxide, and / or their (e.g., any suitable) combination.

[0053] A conductive material (e.g., an electronic conductor) can be used to provide electrode conductivity, and any suitable conductive material that does not cause a chemical change in the battery can be used as the conductive material constituting the battery. For example, the conductive material may include: carbon materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube; metal powders or metal fibers including one or more of copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and / or their (e.g., any suitable) mixture.

[0054] The negative electrode current collector COL2 may include a copper foil, a nickel foil, a stainless - steel foil, a titanium (Ti) foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or their (e.g., any suitable) combination.

[0055] Negative electrode active material

[0056] The negative electrode active material may include: a material that can reversibly intercalate and deintercalate lithium ions, lithium metal, a lithium metal alloy, a material that can be doped and dedoped with lithium, and / or a transition metal oxide.

[0057] The material that can reversibly intercalate and deintercalate lithium ions may include carbon - based negative electrode active materials, e.g., crystalline carbon, amorphous carbon, and / or their (e.g., any suitable) combination. For example, crystalline carbon may include graphite, such as amorphous (e.g., irregular - shaped), flaky, lamellar, spherical, or fibrous natural or artificial graphite, and amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbon, or calcined coke.

[0058] The lithium metal alloy may include an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0059] The material that can be doped and dedoped with lithium may include Si - based negative electrode active materials or Sn - based negative electrode active materials. The Si - based negative electrode active materials may include silicon, silicon - carbon composites, SiOx (0 < x ≤ 2), Si-Q alloy (where Q is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element (except Si or excluding Si), Group 15 element, Group 16 element, transition metal, rare earth element, and / or its (e.g., any suitable) combination) and / or its (e.g., any suitable) combination. The Sn-based negative electrode active material may include Sn, SnO x (0 < x ≤ 2, e.g., SnO2), Sn-based alloy, or a combination thereof.

[0060] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may have a structure in which amorphous carbon is coated on the surface of silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) that aggregate (e.g., agglomerate) primary silicon particles and an amorphous carbon coating (shell) located on the surface of the secondary particles. Amorphous carbon may also be located between the primary silicon particles, and for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0061] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles, and may also include an amorphous carbon coating located on the surface of the core.

[0062] In some embodiments, the Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with a carbon-based negative electrode active material.

[0063] Separator 30

[0064] Based on the type or class of the rechargeable lithium battery, the separator 30 may be present between the positive electrode 10 and the negative electrode 20. The separator 30 may include one or more of a polyethylene separator, a polypropylene separator, and a polyvinylidene fluoride separator, and may have a multilayer structure (such as a polyethylene / polypropylene bilayer separator, a polyethylene / polypropylene / polyethylene trilayer separator, and / or a polypropylene / polyethylene / polypropylene trilayer separator).

[0065] The separator 30 may include a porous substrate and a coating located on one surface or two opposite surfaces of the porous substrate, and the coating may include an organic material, an inorganic material, and / or its (e.g., any suitable) combination.

[0066] The porous substrate can be a polymer layer, which includes: one selected from polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyaryl ether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cycloolefin copolymers, polyphenylene sulfides, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon); or a copolymer or mixture including two or more of the above-mentioned materials.

[0067] The organic material can include polyvinylidene fluoride copolymers or (meth)acrylic copolymers.

[0068] The inorganic material can include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and / or any suitable combination thereof, but the present disclosure is not limited thereto.

[0069] The organic material and the inorganic material can be mixed in one coating, or can be present in a stacked structure of a coating including (e.g., only including) the organic material and a coating including (e.g., only including) the inorganic material.

[0070] Electrolyte ELL

[0071] The electrolyte ELL for a rechargeable lithium battery can include a non-aqueous organic solvent and a lithium salt.

[0072] The non-aqueous organic solvent can be used as a medium for transporting (e.g., conveying) ions participating in the electrochemical reaction of the battery.

[0073] The non-aqueous organic solvent can include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and / or any suitable combination thereof.

[0074] The carbonate solvents can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and / or butylene carbonate (BC).

[0075] The ester solvents can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanolide, mevalonolactone, valerolactone, and / or caprolactone.

[0076] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and / or tetrahydrofuran. Ketone solvents may include cyclohexanone. Aprotic solvents may include one or more nitriles such as R-CN (wherein R is a hydrocarbon group having a C2-C20 straight-chain, branched-chain, or cyclic structure and may include double bonds, aromatic rings, or ether groups); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane and / or 1,4-dioxolane); and / or sulfolane.

[0077] The non-aqueous organic solvent may be used alone or as a mixture of two or more substances (e.g., solvents).

[0078] In one or more embodiments, if (e.g., when) a carbonate solvent is used, then a cyclic carbonate and a linear carbonate may be mixed and used, and the cyclic carbonate and the linear carbonate may be mixed at a volume ratio of about 1:1 to about 1:9.

[0079] The lithium salt may be a material dissolved in a non-aqueous organic solvent, used as a lithium ion supply source in a battery, and plays a role in ensuring the basic operation of a rechargeable lithium battery and promoting the movement of lithium ions between the positive and negative electrodes. The lithium salt may include, for example, at least one selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are each independently an integer between 1 and 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluoro bis(oxalato)phosphate (LiDFBOP), and lithium bis(oxalato)borate (LiBOB).

[0080] In some embodiments, the lithium salt may include LiPF6.

[0081] The lithium salt may have a concentration of about 0.1 M to about 2.0 M.

[0082] In some embodiments, the additive may include a vinylene carbonate compound. The vinylene carbonate compound may be added to the electrolyte to form a solid electrolyte interface (SEI) layer. The vinylene carbonate compound may be vinylene carbonate, ethylene vinylene carbonate, and / or a combination thereof (e.g., any suitable combination).

[0083] The amount of the vinylene carbonate compound may be about 0.01 wt% to about 5 wt% relative to (e.g., based on) the total weight of the electrolyte. For example, relative to the total weight of the electrolyte, the vinylene carbonate compound may have an amount equal to or greater than about 0.05 wt%, equal to or greater than about 0.1 wt%, or equal to or greater than about 0.5 wt%. Relative to the total weight of the electrolyte, the vinylene carbonate compound may have an amount equal to or less than about 3 wt%, equal to or less than about 2 wt%, or equal to or less than about 1.5 wt%. When the vinylene carbonate compound has the aforementioned concentration (e.g., amount) in the electrolyte, a SEI layer (hereinafter, also referred to as "protective film") having a suitable or appropriate resistance (e.g., film resistance) can be formed on the electrode surface of the rechargeable lithium battery to improve the cycling characteristics of the rechargeable lithium battery.

[0084] The additive may include Compound 1 represented by Chemical Formula 1.

[0085] [Chemical Formula 1]

[0086]

[0087] In Chemical Formula 1, R1 to R4 may each independently be a hydrogen atom, a halogen atom, or a substituted or unsubstituted C1-C5 alkyl group. In some embodiments, in Chemical Formula 1, R1 to R4 may each be a hydrogen atom.

[0088] Relative to (e.g., based on) the total weight of the electrolyte, Compound 1 may have an amount of about 0.01 wt% to about 5 wt% (e.g., 0.01 wt% to 1 wt%). For example, relative to the total amount of the electrolyte, Compound 1 may have an amount equal to or greater than about 0.05 wt% or equal to or greater than about 0.1 wt%. Relative to the total weight of the electrolyte, Compound 1 may have an amount equal to or less than about 3 wt%, equal to or less than about 1.5 wt%, or equal to or less than about 1 wt%. When Compound 1 has the aforementioned concentration (e.g., amount), a protective film having a suitable or appropriate film resistance can be formed on the electrode surface of the rechargeable lithium battery to improve the cycling characteristics of the rechargeable lithium battery, and gas generation in the rechargeable lithium battery can be inhibited or reduced to improve the high-temperature life and high-temperature storage performance of the rechargeable lithium battery.

[0089] The additive may include Compound 2 represented by Chemical Formula 2.

[0090] [Chemical Formula 2]

[0091]

[0092] An additive including a compound represented by Chemical Formula 2 can be added to an electrolyte for a rechargeable lithium battery, and thus the battery performance (such as life characteristics) of the rechargeable lithium battery can be improved, and gas generation and resistance increase rate at high temperature can be reduced.

[0093] The compound represented by Chemical Formula 2 may include a structure in which two sulfate rings are connected to each other in a spiro form.

[0094] Relative to (e.g., based on) the total weight of the electrolyte, Compound 2 may have an amount of about 0.01 wt% to about 5 wt% (e.g., 0.01 wt% to 2 wt%). For example, relative to the total weight of the electrolyte, Compound 2 may have an amount equal to or greater than about 0.05 wt%, equal to or greater than about 0.1 wt%, or equal to or greater than about 0.5 wt%. Relative to the total weight of the electrolyte, Compound 2 may have an amount equal to or less than about 3 wt%, equal to or less than about 2 wt%, or equal to or less than about 1.5 wt%. When Compound 2 has the foregoing concentration, the resistance of the electrode surface of the rechargeable lithium battery can be reduced (e.g., moderately reduced) to improve the battery output performance.

[0095] The additive may include Compound 1 and Compound 2. Based on the combination of Compound 1 and Compound 2, the additive can not only improve the high-temperature performance but also improve the resistance increase rate of the rechargeable lithium battery, thereby improving the battery output performance.

[0096] In the additive, the amount of Compound 1 is less than or equal to the amount of Compound 2. For example, relative to about 1 part by weight of Compound 1, Compound 2 may have an amount of about 1 part by weight to about 20 parts by weight. For example, in the additive, relative to about 1 part by weight of Compound 1, Compound 2 may have an amount of about 1.5 parts by weight to about 15 parts by weight or about 2 parts by weight to about 10 parts by weight. When Compound 1 and Compound 2 have the foregoing ratio, the rechargeable lithium battery can improve the high-temperature performance and the resistance increase rate, which can result in an improvement in the battery output performance.

[0097] Relative to (e.g., based on) the total weight of the electrolyte, the additive may have an amount of about 0.1 wt% to about 10 wt%. For example, relative to the total weight of the electrolyte, the additive may have an amount of about 0.5 wt% to about 7 wt%, about 1 wt% to about 4 wt%, about 2.1 wt% to about 4 wt%, or about 2.5 wt% to about 3.5 wt%. If (e.g., when) the amount of the additive included exceeds the above range (e.g., greater than about 10 wt%), the viscosity of the electrolyte including the additive may increase excessively (or significantly), thereby reducing the wettability to the positive electrode and the negative electrode. In contrast, if (e.g., when) the amount of the additive included is less than the above range (e.g., less than about 0.1 wt%), the above-mentioned effects may not be obvious.

[0098] Rechargeable lithium battery

[0099] Based on the shape of the rechargeable lithium battery, the rechargeable lithium battery can be classified into a cylindrical battery, a prismatic battery, a pouch or pouch-like battery, and a coin or coin-like battery. Figures 2 to 5 Simplified diagrams illustrating a rechargeable lithium battery according to one or more embodiments. Figure 2 Illustrating a cylindrical battery, Figure 3 illustrating a prismatic battery, and Figure 4 and Figure 5 each illustrating a pouch or pouch-like battery. Referring to Figures 2 to 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 in which a separator 30 is disposed between a positive electrode 10 and a negative electrode 20, and may further include a housing 50 that houses the electrode assembly 40. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated in an electrolyte. As Figure 2 illustrated, the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. In one or more embodiments, as Figure 3 illustrated, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. As Figure 4 and Figure 5 illustrated, the rechargeable lithium battery 100 may include an electrode tab 70, or a positive electrode tab 71 and a negative electrode tab 72, which serve as a circuit path for guiding the current generated in the electrode assembly 40 to the outside.

[0100] The rechargeable lithium battery according to one or more embodiments of the present disclosure can be applied to automotive vehicles, mobile phones, and / or any other electronic devices, but the present disclosure is not limited thereto.

[0101] Examples and comparative examples of the present disclosure will be described in more detail below. The following examples are only embodiments of the present disclosure, and the present disclosure is not limited to the following examples.

[0102] Examples and Comparative Examples

[0103] Synthesis Examples

[0104] In a 3-neck round-bottom flask that has been flame-dried, 2.2 g of catechol and 20 mL of dichloromethane are provided, and a solution in which 8.07 g of triethylamine is dissolved in 5 mL of dichloromethane under a nitrogen atmosphere is provided to the 3-neck round-bottom flask. Then, chlorosulfonyl fluoride gas is added while stirring the mixture at 23 °C. Stirring is continued in a gas-filled state. After terminating the reaction, 25 mL of dichloromethane is added together with 50 mL of water, and then the resulting organic layer is extracted three times. The extracted organic layer is washed twice with 25 mL of water and then dried by using magnesium sulfate drying reagent. The solvent is removed from the dried organic layer using a rotary evaporator, and silica filtration purification is carried out to finally obtain the compound represented by Chemical Formula 1-1, and its hydrogen spectrum is as follows.

[0105] * 1 H NMR(400MHz, CDCl3)δ7.21(m, 4H); 13 C NMR(100MHz, CDCl3)δ142.79, 125.50, 112.00;

[0106] [Chemical Formula 1-1]

[0107]

[0108] Example 1

[0109] (1) Preparation of electrolyte

[0110] Approximately 1.0 M of LiPF6 is dissolved in a non-aqueous organic solvent (where ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed in a volume ratio of approximately 20:40:40), and an additive is added to prepare an electrolyte.

[0111] As an additive, Compound 1 represented by Chemical Formula 1-1 is added in an amount of 0.1 wt% based on the total amount of the electrolyte, and Compound 2 represented by Chemical Formula 2 is added in an amount of 1 wt% based on the total amount of the electrolyte.

[0112] [Chemical Formula 1-1]

[0113]

[0114] [Chemical Formula 2]

[0115]

[0116] (2) Fabrication of a rechargeable lithium battery

[0117] LiNi 0.91 Co 0.08 Al0.01 O2, polyvinylidene fluoride as a binder, and acetylene black as a conductive material are mixed at a weight ratio of 96:3:1, and the mixture is distributed (e.g., dispersed) in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0118] The positive electrode active material slurry is coated on an Al foil positive electrode current collector COL1 with a thickness of 15 μm, dried at a temperature of 100 °C, and then pressed to manufacture a positive electrode.

[0119] Silicon negative electrode active material, styrene-butadiene rubber binder, and carboxymethyl cellulose are mixed at a weight ratio of 98:1:1, and distributed (e.g., dispersed) in distilled water to prepare a negative electrode active material slurry.

[0120] The negative electrode active material slurry is coated on a copper (Cu) foil negative electrode current collector COL2 with a thickness of 10 μm, dried at 100 °C, and then pressed to manufacture a negative electrode.

[0121] The positive electrode, negative electrode, and a 10-μm-thick polyethylene separator are assembled to prepare an electrode assembly, and an electrolyte is introduced to manufacture a rechargeable lithium battery.

[0122] Example 2

[0123] A rechargeable lithium battery is prepared in substantially the same manner as in Example 1, except that, as an additive, Compound 1 is added in an amount of 0.5 wt% based on the total amount of the electrolyte, and Compound 2 is added in an amount of 1 wt% based on the total amount of the electrolyte.

[0124] Example 3

[0125] A rechargeable lithium battery is prepared in substantially the same manner as in Example 1, except that, as an additive, Compound 1 is added in an amount of 1 wt% based on the total amount of the electrolyte, and Compound 2 is added in an amount of 1 wt% based on the total amount of the electrolyte.

[0126] Example 4

[0127] A rechargeable lithium battery is prepared in substantially the same manner as in Example 1, except that, as an additive, Compound 1 is added in an amount of 1.5 wt% based on the total amount of the electrolyte, and Compound 2 is added in an amount of 1 wt% based on the total amount of the electrolyte.

[0128] Comparative Example 1

[0129] A rechargeable lithium battery was prepared in substantially the same manner as in Example 1, except that, as an additive, vinylene carbonate was added in an amount of 1.5 wt% based on the total amount of the electrolyte, ethylene vinylene carbonate was added in an amount of 0.5 wt% based on the total amount of the electrolyte, and neither Compound 1 nor Compound 2 was added.

[0130] Comparative Example 2

[0131] A rechargeable lithium battery was prepared in substantially the same manner as in Example 1, except that, as an additive, Compound 1 was not added, and Compound 2 was added in an amount of 1 wt% based on the total amount of the electrolyte.

[0132] Comparative Example 3

[0133] A rechargeable lithium battery was prepared in substantially the same manner as in Example 1, except that, as an additive, Compound 1 was not added, and Compound 2 was added in an amount of 1.5 wt% based on the total amount of the electrolyte.

[0134] Evaluation Example

[0135] The rechargeable lithium battery was evaluated by the following method.

[0136] Evaluation 1: Life characteristics of the rechargeable lithium battery at 45 °C

[0137] (1) Capacity retention rate

[0138] The rechargeable lithium batteries according to each of the Examples and Comparative Examples were fabricated in the form of a 7 Ah prismatic or pouch-type battery, and at 25 °C, the battery was charged to 4.25 V / 350 mA at a rate of 0.33C under constant current and constant voltage (CC / CV), and then the battery was discharged at a rate of 0.33C under constant current (CC) until its voltage reached 2.8 V while using a charge / discharge device (e.g., PNE-0506 commercially available from PNE Solution Co., Ltd.) to measure the initial capacity. Additionally, at 45 °C, the same battery was charged to 4.25 V / 350 mA at a rate of 0.33C under constant current and constant voltage (CC / CV), and then discharged at a rate of 0.5C under constant current (CC) until its voltage reached 2.8 V. After repeating this process 300 times, the discharge capacity (i.e., the discharge capacity after 300 cycles) was measured.

[0139] The measured discharge capacity was used to calculate the capacity retention rate according to Equation 1, and the results are listed in Table 1.

[0140] [Equation 1]

[0141] Capacity retention rate (%) = (Discharge capacity after 300 cycles / Initial discharge capacity) × 100

[0142] (2) DCIR increase rate

[0143] After measuring the ΔV / ΔI (voltage change / current change) of the rechargeable lithium batteries according to each of the examples and comparative examples as the initial direct current internal resistance (initial DCIR), the maximum energy state of the battery was changed to a fully charged state (SOC 100%). In this state, the battery was discharged at a rate of 0.33C under constant current (CC) until its voltage reached 2.8V. After repeating this process 300 times, the direct current internal resistance (DCIR) was measured (i.e., the DCIR after 300 cycles), the DCIR increase rate (%) was calculated according to Equation 2, and the results are listed in Table 1.

[0144] [Equation 2]

[0145] DCIR increase rate (%) = (DCIR after 300 cycles / Initial DCIR) × 100

[0146] Evaluation 2: Storage characteristics of rechargeable lithium batteries at 60°C

[0147] (1) Capacity retention rate

[0148] The rechargeable lithium batteries according to the examples and comparative examples were prepared in the form of a 7Ah prism or similar, and at 25°C, the battery was charged to 4.25V / 350mA at a rate of 0.33C under constant current and constant voltage (CC / CV). After that, while discharging the battery at a rate of 0.33C under constant current (CC) until its voltage reached 2.8V, the initial capacity was measured using a charge / discharge device (e.g., PNE-0506 commercially available from PNE Solution Co., Ltd.). Additionally, at 25°C, the same battery was charged to 4.25V / 350mA at a rate of 0.33C under constant current and constant voltage (CC / CV), and then stored in an oven at 60°C for 30 days. Thereafter, while discharging the battery at a rate of 0.33C under constant current (CC) until its voltage reached 2.8V, the discharge capacity (i.e., the discharge capacity after 30 days) was measured using the above device.

[0149] The measured discharge capacity was used to calculate the capacity retention rate according to Equation 3, and the results are listed in Table 1.

[0150] [Equation 3]

[0151] Capacity retention rate (%) = (Discharge capacity after 30 days / Initial discharge capacity) × 100

[0152] (2) DCIR Increase Rate

[0153] After allowing rechargeable lithium batteries according to the examples and comparative examples to measure their ΔV / ΔI (voltage change / current change) as the initial direct current internal resistance (initial DCIR), the maximum energy state of the battery is changed to a fully charged state (SOC 100%). In this state, the battery is stored in a high-temperature oven at 60 °C for 30 days, the direct current internal resistance is measured (i.e., the direct current internal resistance after 30 days), the DCIR increase rate (%) is calculated according to Equation 4, and the results are listed in Table 1.

[0154] [Equation 4]

[0155] DCIR Increase Rate (%) = (DCIR after 30 days / Initial DCIR) × 100

[0156] Table 1

[0157]

[0158]

[0159] - and - * indicate not added (excluded).

[0160] The electrolyte according to one or more embodiments for a rechargeable lithium battery can achieve the stability of the electrode and the suppression of the increase in resistance, and thus can have the effect of improving the stability and life characteristics at relatively high temperatures.

[0161] When describing the embodiments of the inventive concept, the use of "may" refers to "one or more embodiments of the inventive concept".

[0162] As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. Throughout this disclosure, the expressions "at least one selected from a, b, and c", "at least one selected from the group consisting of a, b, and c", "at least one of a, b, and c", "at least one selected from among a, b, and c", etc. indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0163] As used herein, the term "about" and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations of measured or calculated values recognized by one of ordinary skill in the art. As used herein, "about" includes the recited value and means an acceptable variation range of the recited value determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the particular quantity of measurements (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the recited value, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0164] Also, any numerical range recited herein is intended to include all sub-ranges of the same numerical precision falling within the recited range. For example, a range of "1.0 to 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including 1.0 and 10.0), i.e., all sub-ranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0 (such as, for example, 2.4 to 7.6). Any maximum numerical limit recited herein is intended to include all lower numerical limits falling therein, and any minimum numerical limit recited in this specification is intended to include all higher numerical limits falling therein. Accordingly, the applicant reserves the right to modify this specification (including the claims) to expressly recite any sub-ranges that fall within the ranges expressly recited herein.

[0165] The battery management system (BMS) device and / or any other relevant device or component according to an embodiment of the invention described herein can be implemented using any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the device can be formed on one integrated circuit (IC) chip or on separate IC chips. Further, the various components of the device can be implemented on a flexible printed circuit film, tape carrier package (TCP), or printed circuit board (PCB), or formed on a substrate. Further, the various components of the device can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which can be implemented using standard memory devices (such as, for example, random access memory (RAM)) in a computing device. The computer program instructions can also be stored in other non-transitory computer-readable media (such as, for example, CD-ROM, flash drive, etc.). And, one of ordinary skill in the art should recognize that, without departing from the scope of this disclosure, the functions of various computing devices can be combined or integrated into a single computing device, or the functions of a particular computing device can be distributed over one or more other computing devices.

[0166] Although the present disclosure has been described in connection with example embodiments that are presently regarded as practical, it should be understood that the present disclosure is not limited to the disclosed embodiments, and is intended to cover various suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents. Accordingly, the foregoing embodiments should be understood as examples and should not limit the present disclosure in any way.

Claims

1. An electrolyte comprising: Non-aqueous organic solvents; Lithium salts; and additive, wherein the additive comprises a compound 1 represented by chemical formula 1 and a compound 2 represented by chemical formula 2, [Chemical formula 1] [Chemical formula 2] Wherein, in Chemical Formula 1, R1 to R4 are each independently a hydrogen atom, a halogen atom, or a substituted or unsubstituted C1 to C5 alkyl group, and The electrolyte is used in rechargeable lithium batteries. 2 . The electrolyte according to claim 1 , wherein the amount of the additive is 0.1 wt % to 10 wt % based on 100 wt % of the total weight of the electrolyte.

3. The electrolyte of claim 1, wherein the amount of Compound 1 is less than or equal to the amount of Compound 2. 4 . The electrolyte according to claim 1 , wherein the amount of Compound 1 is 0.01 wt % to 5 wt % based on 100 wt % of the total weight of the electrolyte. 5 . The electrolyte according to claim 1 , wherein the compound 2 is 0.01 wt % to 5 wt % based on 100 wt % of the total weight of the electrolyte. 6 . The electrolyte according to claim 1 , wherein the amount of Compound 2 is 1 to 20 parts by weight relative to 1 part by weight of Compound 1.

7. The electrolyte according to claim 1, wherein R1 to R4 are each a hydrogen atom.

8. The electrolyte of claim 1, wherein the nonaqueous organic solvent comprises at least one selected from the group consisting of ethylene carbonate, propylene carbonate, propyl propionate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, and butylene carbonate. 9 . The electrolyte of claim 8 , wherein the nonaqueous organic solvent comprises ethylene carbonate, ethylmethyl carbonate, and dimethyl carbonate.

10. The electrolyte of claim 1, wherein the lithium salt comprises a salt selected from the group consisting of LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide, LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate, lithium difluorobis(oxalate)phosphate and lithium bis(oxalate)borate, wherein x and y are each independently an integer between 1 and 20.

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

12. A rechargeable lithium battery comprising: a positive electrode, including a positive electrode active material; a negative electrode, including a negative electrode active material; and The electrolyte according to any one of claims 1 to 11.

13. The rechargeable lithium battery of claim 12, wherein the positive electrode active material comprises a lithium metal oxide represented by Chemical Formula 3, [Chemical formula 3] Li a Ni 1-b-c Co b X c O 2-α D α Wherein in chemical formula 3, X is Al, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof, D is F, S, P or a combination thereof, 0.90≤a≤1.8， 0≤b≤0.5， 0≤c≤0.5, and 0<α<2。 14 . The rechargeable lithium battery of claim 12 , wherein the negative electrode active material comprises a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, or a combination thereof.

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