Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention provides an electrolyte for a rechargeable lithium battery 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 first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2. Chemical formula 1 # imgabs0 # and chemical formula 2 # imgabs1 #

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0033253, filed on March 8, 2024, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

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

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

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode and the negative electrode each include an active material in which (e.g., lithium ions) can be intercalated and deintercalated, and if (e.g., when) lithium ions are intercalated and deintercalated, the rechargeable lithium battery generates electrical energy due to oxidation and reduction reactions.

[0006] Lithium salts dissolved in non-aqueous organic solvents serve as electrolytes for rechargeable lithium batteries. The characteristics of rechargeable lithium batteries 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 an important variable for improving rechargeable lithium batteries. Summary of the Invention

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

[0008] Aspects according to one or more embodiments relate to a rechargeable lithium battery including an electrolyte.

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

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

[0011] The additive may include a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2.

[0012] Chemical formula 1

[0013]

[0014] In Chemical Formula 1,

[0015] X 1 It may be a fluoro group, a chloro group, a bromo group or an iodo group.

[0016] R 1 ~R 6 They may each independently be hydrogen, cyano, 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.

[0017] n can be an integer of 0 or 1.

[0018] Chemical formula 2

[0019]

[0020] In Chemical Formula 2,

[0021] L 2A and L 2B Each may independently be a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group.

[0022] A and B may each independently be a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0023] At least one selected from A and B may be a group represented by Chemical Formula A.

[0024] Chemical formula A

[0025]

[0026] In chemical formula A,

[0027] R 7 and R 8 They may each independently be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

[0028] 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 for a rechargeable lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0030] Figures 2 to 5 Simplified diagrams each illustrating an embodiment of a rechargeable lithium battery of the present disclosure are illustrated, wherein Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 A pouch type or similar battery is shown. DETAILED DESCRIPTION

[0031] In order to fully understand the layout and aspects 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 example embodiments and can be implemented in one or more suitable forms. On the contrary, the example embodiments are provided only to disclose the present disclosure and to make those skilled in the art fully aware of the scope of the present disclosure.

[0032] In this description, it will be understood that if (for example, when) an element is referred to as being on another element, the element may be directly on the other element, or intervening elements may be present therebetween. In the drawings, the sizes (for example, thickness) of some components are exaggerated for the purpose of effectively explaining the technical content. The same reference numerals refer to the same elements throughout the specification, and their repeated descriptions may not be provided in the specification.

[0033] Unless otherwise specifically stated in this description, expressions in the singular may include expressions in the plural. In addition, unless otherwise specifically stated, the phrase "A or B" may indicate "A but not B," "B but not A," and "A and B." The terms "comprises / includes" and / or "comprising / including" used in this description do not exclude the presence or addition of one or more other components.

[0034] As used herein, the term "combination thereof" may refer to a mixture, stack, composite, copolymer, alloy, blend, or reaction product of the components.

[0035] Unless otherwise specifically defined in the present description, the particle size may be an average particle size. In addition, the particle size indicates the average particle size (D 50 ). Average particle size (D50 ) can be measured by a method suitable for those skilled in the art (e.g., by a particle size analyzer, a transmission electron microscope (TEM) image, or a scanning electron microscope (SEM) image). In one or more embodiments, a dynamic light scattering measurement device is used for data analysis, the number of particles in each particle size range is counted, and the average particle size (D) is then calculated. 50 ) value. The difference is that the laser scattering method can be used to measure the average particle size (D 50 In the laser scattering method, target particles are distributed in a distribution solvent, introduced into a laser scattering particle measuring device (e.g., MT3000 commercially available from Microtrac, Inc.), irradiated with 28 kHz ultrasonic waves at a power of 60 W, and then the average particle size (D) is calculated in the measuring device based on a 50% standard particle size distribution. 50 ).

[0036] As used herein, expressions such as "at least one of," "one of," and "(e.g., selected from)...", when preceding or following a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, "at least one of a, b, and c," "at least one selected from a, b, and c," etc. may indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0037] The terms used in this article are intended to describe only specific embodiments and are not intended to limit the present disclosure. As used in this article, the singular forms "a", "an" and "the" are intended to include plural forms, including "at least one", unless the content (e.g., quantity) is otherwise clearly indicated. "At least one" should not be interpreted as being limited to the singular. As used in this article, the term "and / or" includes any and all combinations of one or more related enumerated items. When used in the detailed description, the terms "includes", "including", "comprises" and / or "comprising" indicate the presence of the described features, regions, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and / or groups thereof.

[0038] Spatially relative terms such as "below," "beneath," "below," "above," "on," etc. are used herein to easily describe the relationship of one element or feature to another element or feature. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the drawings. For example, when the device in the drawings is turned over, elements described as "below" or "beneath" other elements or features will be "above" or "on" the other elements or features. In some embodiments, the example term "below" can encompass both (e.g., simultaneously) orientations of above and below. The device can be oriented otherwise (rotated 90 degrees or in other orientations), and the spatially relative terms used herein can be interpreted accordingly.

[0039] As used herein, the term "substantially" and similar terms are used as terms of approximation rather than as terms of degree, and are intended to account for the inherent deviations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. Furthermore, the term "about" and similar terms, when used herein in conjunction with a value or range of values, include the stated value as well as values ​​within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and errors associated with the measurement of the particular quantity (e.g., limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0040] Furthermore, any numerical range set forth in this article is intended to include all subranges of the same numerical precision included in the range of the setting forth. For example, the range of "1.0 to 10.0" is intended to include all subranges between the minimum value 1.0 set forth and the maximum value 10.0 set forth (and including 1.0 and 10.0), that is, all subranges with a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0 (such as, for example, 2.4 to 7.6). Any maximum numerical limit set forth in this article is intended to include all lower numerical limits contained therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits contained therein. Accordingly, the applicant reserves the right to amend this specification (including claims) to explicitly set forth any subrange contained in the range explicitly set forth in this article.

[0041] In the present description, unless otherwise defined separately, the term "substituted" may refer to a substituent or a compound in which at least one hydrogen is replaced by deuterium, a halo group, a hydroxyl group, an amino group, a C1-C30 amine 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 (e.g., any appropriate) combination thereof.

[0042] For example, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or compound by deuterium, halogen, 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. For example, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or compound by deuterium, halogen, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. In one or more embodiments, the term "substituted" may refer to the replacement of at least one hydrogen of a substituent or compound by deuterium, halogen, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, or cyano. For example, the term "substituted" may refer to a substituent or compound in which at least one hydrogen is replaced by deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0043] The alkyl group may include a linear alkyl group and / or a chain alkyl group, and the cycloalkyl group may include a cyclic alkyl group.

[0044] Figure 1 A conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated. Figure 1 , a rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0045] The positive electrode 10 and the negative electrode 20 may be spaced and / or separated (e.g., spaced or separated) from each other 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. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in the electrolyte ELL.

[0046] The electrolyte ELL may be a medium for lithium ions to be transferred between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, the lithium ions may move toward one of the positive electrode 10 and the negative electrode 20 through the separator 30.

[0047] Positive electrode 10

[0048] 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 a positive electrode active material and further include a binder and / or a conductive material.

[0049] For example, the positive electrode 10 may further include a component that may serve as a sacrificial positive electrode.

[0050] The amount of the positive electrode active material may range from about 90 wt % to about 99 wt % relative to 100 wt % of the positive electrode active material layer AML1. The amount of the binder and the conductive material may each range from about 0.5 wt % to about 5 wt % relative to 100 wt % of the positive electrode active material layer AML1.

[0051] The binder can be used to improve the adhesion of the positive electrode active material particles to each other and also to improve the adhesion of the positive electrode active material to the positive electrode current collector COL 1. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an ethylene oxide-containing polymer, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, and / or nylon, but the present disclosure is not limited thereto.

[0052] Conductive materials can be used to provide conductivity to the electrodes, and any suitable conductive material that does not cause chemical changes in the battery can be used as the conductive material constituting the battery. Conductive materials may include, for example, carbon materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes); metal powders or metal fibers containing one or more of copper, nickel, aluminum, and silver; conductive polymers (such as polyphenylene derivatives); and / or (for example, any suitable) mixtures thereof.

[0053] An aluminum (Al) foil may be used as the positive electrode current collector COL1 , but the present disclosure is not limited thereto.

[0054] Positive electrode active material

[0055] The positive electrode active material in the positive electrode active material layer AML1 may include a compound that reversibly intercalates and deintercalates lithium (e.g., a lithiated intercalation compound). For example, the positive electrode active material may include at least one type of composite oxide containing lithium and a metal selected from cobalt, manganese, nickel, and / or any suitable combination thereof.

[0056] The composite oxide may include a lithium transition metal composite oxide, such as lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel manganese-based oxides, and / or (eg, any appropriate) combinations thereof.

[0057] For example, the positive electrode active material may include a compound represented by any 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); 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 Mn1-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).

[0058] In the above chemical formula, A is Ni, Co, Mn and / or (e.g., any appropriate) combination thereof, X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element and / or (e.g., any appropriate) combination thereof, D is O, F, S, P and / or (e.g., any appropriate) combination thereof, G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or (e.g., any appropriate) combination thereof, and L 1 is Mn, Al, and / or (eg, any suitable) combination thereof.

[0059] For example, the positive electrode active material may be a high nickel-based positive electrode active material having a nickel content (e.g., amount) of about 80 mol% or more, about 85 mol% or more, about 90 mol% or more, about 91 mol% or more, or about 94 mol% or more and about 99 mol% or less relative to 100 mol% of the lithium-free metal in the lithium transition metal composite oxide. The high nickel-based positive electrode active material can achieve high capacity and can therefore be applied to high capacity and high energy density rechargeable lithium batteries.

[0060] Negative electrode 20

[0061] The negative electrode 20 for a rechargeable lithium battery may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 on the negative electrode current collector COL2. The negative electrode active material layer AML2 may include a negative electrode active material and may further include a binder and / or a conductive material.

[0062] For example, 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.

[0063] The binder can be used to improve the adhesion of the negative electrode active material particles to each other and also to improve the adhesion of the negative electrode active material to the negative electrode current collector COL2. The binder can include a non-aqueous binder, an aqueous binder, a dry binder, and / or any suitable combination thereof.

[0064] 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 (eg, any suitable) combinations thereof.

[0065] The aqueous binder may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and / or (e.g., any suitable) combination thereof.

[0066] When an aqueous binder is used as a binder in the negative electrode active material layer AML2, a cellulose compound capable of providing viscosity may be further included. The cellulose compound may include one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal may include Na, K, or Li.

[0067] The dry binder may include a fibrillated polymeric material, such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or (eg, any suitable) combinations thereof.

[0068] Conductive materials can be used to provide conductivity to the electrodes, and any suitable conductive material that does not cause chemical changes in the battery can be used as the conductive material constituting the battery. For example, the conductive material may include carbon materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes); metal powders or metal fibers including one or more of copper, nickel, aluminum, and silver; conductive polymers (such as polyphenylene derivatives); and / or (for example, any suitable) mixtures thereof.

[0069] The negative electrode current collector COL2 may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or (eg, any appropriate) combinations thereof.

[0070] Negative electrode active material

[0071] The negative electrode active material in the negative electrode active material layer AML2 may include a material that can reversibly intercalate and deintercalate lithium ions, lithium metal, a lithium metal alloy, a material that can dope and dedope lithium, or a transition metal oxide.

[0072] Materials that can reversibly embed and deembed lithium ions may include carbonaceous negative electrode active materials, such as crystalline carbon, amorphous carbon, and / or combinations thereof (e.g., any suitable combination). For example, crystalline carbon may include graphite, such as natural or artificial graphite that is amorphous, flaky, lamellar, spherical, or fibrous, and amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbon, or calcined coke.

[0073] Lithium metal alloys may include alloys of lithium with metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0074] Materials that can be doped and undoped with lithium may include Si-based negative electrode active materials (also referred to as "Si-based negative electrode active materials") or Sn-based negative electrode active materials. Si-based negative electrode active materials may include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (where Q is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element (excluding Si), Group 15 element, Group 16 element, transition metal, rare earth element, and / or combinations thereof (e.g., any suitable combination)), or combinations thereof. Sn-based negative electrode active materials may include: Sn; SnO x (0 < x ≤ 2), such as SnO2; Sn-based alloys; or combinations thereof (e.g., any suitable combination).

[0075] 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 coats the surface of silicon particles. For example, the silicon-carbon composite may include secondary particles (cores) that aggregate 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. For example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0076] 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.

[0077] Si-based negative electrode active materials or Sn-based negative electrode active materials may be used in combination with carbonaceous negative electrode active materials.

[0078] In one or more embodiments, the negative electrode active material may include a carbonaceous negative electrode active material and a Si-based negative electrode active material. The negative electrode active material may include carbon (C) and silicon (Si). For example, the carbonaceous negative electrode active material may include graphite, and the Si-based negative electrode active material may include silicon nanoparticles.

[0079] The weight ratio of the silicon nanoparticles to the graphite may be in the range of about 0.001 to about 20 or about 1 to about 10. When the weight ratio of the silicon nanoparticles to the graphite is within the above range, a buffering effect on volume expansion of the silicon nanoparticles may be increased to achieve excellent or appropriate conductivity and improve lifespan characteristics.

[0080] Silicon nanoparticles may refer to nano-sized silicon particles. The silicon nanoparticles may have an average particle size in the range of about 50 nanometers (nm) to 300 nm (e.g., about 80 nm to 200 nm). When the silicon particles have a nano-size, smooth insertion / extraction of lithium ions and low ionic resistance can be achieved, thereby suppressing or reducing volume expansion and improving life characteristics.

[0081] Diaphragm 30

[0082] Depending on the type or kind of 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 be a multilayer separator thereof, such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, and a polypropylene / polyethylene / polypropylene three-layer separator.

[0083] The separator 30 may include a porous substrate and a coating on one or opposite surfaces of the porous substrate, the coating including an organic material, an inorganic material, and / or (eg, any suitable) combination thereof.

[0084] The porous substrate may be a polymer layer comprising one selected from polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene oxides, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon), or may be a copolymer or mixture comprising two or more of the above-mentioned materials.

[0085] The organic material may include a polyvinylidene fluoride-based copolymer or a (meth)acrylic acid-based copolymer.

[0086] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and inorganic particles selected from (e.g., any suitable) combinations thereof, but the present disclosure is not limited thereto.

[0087] The organic material and the inorganic material may be present as a mixture in one coating layer, or may be present as a stack of a coating layer including an organic material and a coating layer including an inorganic material.

[0088] Electrolyte ELL

[0089] The electrolyte ELL for a rechargeable lithium battery may include a non-aqueous organic solvent and a lithium salt.

[0090] The non-aqueous organic solvent may serve as a medium for transporting ions participating in the electrochemical reaction of the battery.

[0091] The non-aqueous organic solvent may include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or (eg, any appropriate) combinations thereof.

[0092] The carbonate-based solvent may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), or butylene carbonate (BC).

[0093] The ester solvent may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, propyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, or caprolactone.

[0094] Ether solvents may include dibutyl ether, tetraglyme, diglyme, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, or tetrahydrofuran. Ketone solvents may include cyclohexanone. Alcohol solvents may include ethanol, isopropanol, and the like. Aprotic solvents may include nitriles (such as R-CN, where R is a hydrocarbon group having a C2 to C20 linear, branched, or cyclic structure and may include a double bond, an aromatic ring, or an ether group); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane or 1,4-dioxolane); or sulfolane.

[0095] The nonaqueous organic solvent may be used alone or as a mixture of two or more species.

[0096] In addition, if (for example, when) a carbonate-based solvent is used, cyclic carbonate and chain carbonate may be mixed and used, and may be mixed in a volume ratio of about 1:1 to about 1:9.

[0097] The lithium salt may be a material dissolved in a non-aqueous organic solvent to serve as a supply source of lithium ions in the battery, and plays a role in ensuring the basic operation of the rechargeable lithium battery and promoting the movement of lithium ions between the positive electrode and the negative electrode. The lithium salt may include, for example, a material 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 integers of 1 to 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBOP) and lithium bis(oxalato)borate (LiBOB).

[0098] An electrolyte for a rechargeable lithium battery according to one or more embodiments will be described in more detail below.

[0099] An electrolyte for a rechargeable lithium battery according to one or more embodiments may include a non-aqueous organic solvent, a lithium salt, and an additive.

[0100] The additive may include a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2.

[0101] Chemical formula 1

[0102]

[0103] In Chemical Formula 1,

[0104] X 1 It may be a fluoro group, a chloro group, a bromo group or an iodo group.

[0105] R 1 ~R 6 They may each independently be hydrogen, cyano, 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.

[0106] n can be an integer of 0 or 1.

[0107] Chemical formula 2

[0108]

[0109] In Chemical Formula 2,

[0110] L 2A and L 2B may each independently be a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group,

[0111] A and B may each independently be a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0112] At least one selected from A and B may be a group represented by Chemical Formula A.

[0113] Chemical formula A

[0114]

[0115] In chemical formula A,

[0116] R 7 and R 8 They may each independently be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

[0117] The electrolyte can be prepared by a mixing process, wherein a lithium salt is dissolved in a non-aqueous organic solvent, and a first additive and a second additive are added to mix. The mixing process of the electrolyte is a mixing process suitable for the field of electrolyte preparation, and those skilled in the art will be able to appropriately or properly select and use the mixing process of the electrolyte.

[0118] The non-aqueous organic solvent may include at least one selected from ethylene carbonate (EC), propylene carbonate (PC), propyl propionate (PP), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) and butylene carbonate (BC).

[0119] In one or more embodiments, the non-aqueous organic solvent may be a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC).

[0120] For example, the amount of ethylene carbonate (EC) included in the non-aqueous organic solvent may be about 10 vol% to about 30 vol%, the amount of ethyl methyl carbonate (EMC) included in the non-aqueous organic solvent may be about 5 vol% to about 20 vol%, and the amount of dimethyl carbonate (DMC) included in the non-aqueous organic solvent may be about 50 vol% to about 80 vol%.

[0121] In one or more embodiments, the lithium salt may include LiPF 6 .

[0122] The lithium salt may have a concentration of about 0.1 M to about 2.0 M. For example, the lithium salt may have a concentration equal to or greater than about 0.5 M or about 1.0 M. The lithium salt may have a concentration equal to or less than about 2.0 M, equal to or less than about 1.7 M, or equal to or less than about 1.5 M. In the present disclosure, if (for example, when) the lithium salt has a concentration of about 0.1 M to about 2.0 M, the electrolyte may suitably or appropriately maintain its conductivity and viscosity.

[0123] First compound

[0124] The first compound according to one or more embodiments of the present disclosure may be represented by Chemical Formula 1.

[0125] Chemical formula 1

[0126]

[0127] In Chemical Formula 1,

[0128] X 1 It may be a fluoro group, a chloro group, a bromo group or an iodo group.

[0129] R 1 ~R 6 They may each independently be hydrogen, cyano, 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.

[0130] n can be an integer of 0 or 1.

[0131] The first compound can form a solid electrolyte interface (SEI) layer having high temperature stability and excellent or appropriate ionic conductivity on the surface of the negative electrode. In addition, the first compound can reduce gas generation caused by decomposition reactions occurring in the electrolyte during high temperature storage. For example, the -PO2F functional group of the first compound can stabilize the thermal decomposition products of lithium salts (such as LiPF6) or ions dissociated from the lithium salt to reduce the generation of gases (such as HF). The formation of an excellent or appropriate SEI layer and the reduction of gas generation can contribute to the improvement of the life characteristics of the battery and the reduction of internal resistance.

[0132] If (for example, when) the first compound is used together with a high-nickel positive electrode active material and a negative electrode active material including graphite and silicon nanoparticles, the improvement in the battery's life characteristics at high temperatures and the reduction in internal resistance caused by the first compound can become significant. For example, silicon nanoparticles can be used to increase battery capacity, but there may be a problem of increased battery internal resistance due to side reactions between the silicon nanoparticles and the electrolyte. When the first compound is introduced as an additive, the side reactions between the silicon nanoparticles and the electrolyte can be suppressed or reduced, not only minimizing or reducing the increase in battery internal resistance, but also maximizing or increasing the increase in battery capacity.

[0133] The first compound may include a cyclic phospholane derivative. Compared to linear phosphite derivatives, cyclic phospholane derivatives can significantly improve the lifespan characteristics of rechargeable lithium batteries. This is due to the fact that linear phosphite derivatives trigger side reactions of LiPF6 due to dissociated –PO2F functional groups and lead to gas generation due to decomposition reactions of the electrolyte during high-temperature storage.

[0134] In one or more embodiments, Chemical Formula 1 may be represented by Chemical Formula 1-1 or 1-2.

[0135] Chemical formula 1-1

[0136]

[0137] Chemical formula 1-2

[0138]

[0139] In Chemical Formula 1-1 and Chemical Formula 1-2,

[0140] X 1 It may be a fluoro group, a chloro group, a bromo group or an iodo group.

[0141] R 1 ~R 6They may each independently be hydrogen, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

[0142] In one or more embodiments, R in the above Chemical Formula 1-1 3 and R 4 Each may be hydrogen.

[0143] Selected from R 5 and R 6 At least one of them may be a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

[0144] In one or more embodiments, the first compound may be any one selected from the compounds listed in Group 1. For example, the first compound may be at least one selected from 2-fluoro-1,3,2-dioxaphospholane and 2-fluoro-4-methyl-1,3,2-dioxaphospholane.

[0145] Group 1

[0146]

[0147] Based on 100 parts by weight of the electrolyte for a rechargeable lithium battery, the amount of the first compound may be from about 0.2 parts by weight to about 5.0 parts by weight. For example, based on 100 parts by weight of the electrolyte for a rechargeable lithium battery, the amount of the first compound may be from about 0.5 parts by weight to about 1.5 parts by weight. The amount of the first compound may refer to the weight of the first compound included in the electrolyte based on the total weight of the electrolyte. When the amount of the first compound satisfies the above range, the effect of reducing gas generation and the effect of forming an excellent or appropriate SEI layer at high temperature can be maximized or increased.

[0148] Second compound

[0149] The second compound according to one or more embodiments of the present disclosure may be represented by Chemical Formula 2.

[0150] Chemical formula 2

[0151]

[0152] In Chemical Formula 2,

[0153] L 2A and L 2Bmay each independently be a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group,

[0154] A and B may each independently be a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group.

[0155] At least one selected from A and B may be a group represented by Chemical Formula A.

[0156] Chemical formula A

[0157]

[0158] In chemical formula A,

[0159] R 7 and R 8 They may each independently be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

[0160] The second compound may have the effect of protecting the film with passivation ability formed on the surface of the positive electrode and the surface of the negative electrode. The film formed on the surface of the positive electrode may be referred to as a positive electrode electrolyte interface (CEI) layer, which is a common name in the art, and the film formed on the surface of the negative electrode may be referred to as a solid electrolyte interface (SEI) layer. For example, the triazole group and the sulfone group of the second compound represented above can provide non-shared electron pairs, thereby stabilizing the lithium salt in the electrolyte and providing the effect of a protective film. Therefore, if (for example, when) the film on the surface of the positive electrode and the film on the surface of the negative electrode are corroded by decomposition products of an acid or a lithium salt in the electrolyte, the problem of shortened battery life and increased resistance of the battery can be minimized or reduced. The effect of the protective film can contribute to the improvement of the life characteristics of the rechargeable lithium battery and the reduction of the internal resistance, particularly at high temperatures.

[0161] The second compound may have the effect of forming a film on the surface of the positive electrode. The film formed on the surface of the positive electrode may be referred to as a positive electrode electrolyte interface (CEI) layer, which is a common name in the art. For example, the triazole group and the sulfone group of the second compound may form a coordination bond with the transition metal included in the positive electrode active material, thereby forming a film on the surface of the positive electrode. Therefore, the gas generation caused by the side reaction between the electrolyte and the positive electrode interface can be reduced, and the gas generation and transition metal dissolution caused by the decomposition of the positive electrode active material can be suppressed or reduced. The effect of the protective film can contribute to the improvement of the life characteristics of the rechargeable lithium battery and the reduction of the internal resistance, particularly at high temperatures.

[0162] In addition to having the effect of protecting the film on the surface of the positive electrode and the film on the surface of the negative electrode and generating a film on the surface of the positive electrode, the second compound also has the effect of strengthening the film on the surface of the negative electrode. Therefore, the rechargeable lithium battery can have an improvement in life characteristics and a reduction in internal resistance. The film formed on the surface of the negative electrode can be referred to as a solid electrolyte interface (SEI) layer, which is a common name in the art. The effect of strengthening the film can contribute to the improvement of the life characteristics of the rechargeable lithium battery and the reduction of the internal resistance, particularly at high temperatures.

[0163] The second compound may include a 1,2,4-triazolyl group. Compared to a 1,2,3-triazolyl group, a 1,2,4-triazolyl group can significantly improve the high temperature characteristics of a rechargeable lithium battery. For example, if (for example, when) used together with a high nickel positive electrode active material, a 1,2,4-triazolyl group may become more effective. Compared to a 1,2,4-triazolyl group, when a 1,2,3-triazolyl group forms a film on the surface of the positive electrode by forming a coordination bond with the transition metal included in the positive electrode active material, the spatial arrangement with nickel may be less effective.

[0164] In one or more embodiments, L selected from Chemical Formula 2 2A and L 2B At least one of them may be a substituted or unsubstituted C1-C5 alkylene group.

[0165] In one or more embodiments, L in Chemical Formula 2 2A and L 2B Each independently may be a substituted or unsubstituted C1-C5 alkylene group.

[0166] In one or more embodiments, L selected from Chemical Formula 2 2A and L 2B At least one of them may be a substituted or unsubstituted C2-C5 alkylene group.

[0167] In one or more embodiments, L in Chemical Formula 2 2A and L 2B Each independently may be a substituted or unsubstituted C2-C5 alkylene group.

[0168] In one or more embodiments, the above Chemical Formula 2 may be represented by Chemical Formula 2-1.

[0169] Chemical formula 2-1

[0170]

[0171] In Chemical Formula 2-1,

[0172] L 1 and L 2Each independently may be a substituted or unsubstituted C2-C5 alkylene group.

[0173] R 21A 、R 21B 、R 21C and R 21D They may each independently be hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

[0174] In one or more embodiments, the second compound may be any one selected from the compounds listed in Group 2.

[0175] Group 2

[0176]

[0177] The amount of the second compound may be from about 1 part by weight to about 5 parts by weight based on 100 parts by weight of the electrolyte for a rechargeable lithium battery. The amount of the second compound may refer to the weight of the second compound included in the electrolyte based on the total weight of the electrolyte. When the amount of the second compound satisfies the above range, the effects of protecting the film on the surface of the positive electrode and the film on the surface of the negative electrode, forming a film on the surface of the positive electrode, and strengthening the film on the surface of the negative electrode can be maximized, or the improvement of the life characteristics of the rechargeable lithium battery and the reduction of the internal resistance can be increased.

[0178] additive

[0179] The electrolyte for a rechargeable lithium battery according to the present disclosure may include: a non-aqueous organic solvent, a lithium salt, and an additive. The additive may include a first compound and a second compound.

[0180] When the second compound is used in combination with the first compound, a synergistic effect can be generated. The combination of the first compound and the second compound can effectively improve the problems of shortened life and increased resistance of rechargeable lithium batteries. For example, the effect of the first compound in forming an excellent or appropriate SEI layer and reducing gas generation and the effect of the second compound in inhibiting or reducing transition metal dissolution of the positive electrode and reducing gas generation can be simultaneously produced to maximize or increase the improvement in the characteristics of the lithium battery. This synergistic effect becomes significant particularly at high temperatures.

[0181] Based on 100 parts by weight of the electrolyte for a rechargeable lithium battery, the amount of the additive may be about 1.2 parts by weight to about 10 parts by weight. The amount of the additive may refer to the weight of the additive included in the electrolyte based on the total weight of the electrolyte. When the amount of the additive satisfies the above range, the rechargeable lithium battery can maximize or increase the improvement in capacity retention, the improvement in resistance increase rate, and the reduction in the amount of transition metal dissolution. This improvement in battery characteristics can become significant, particularly at high temperatures.

[0182] The weight ratio of the second compound to the first compound in the electrolyte may be in the range of about 0.2 to about 25. For example, the weight ratio of the second compound to the first compound in the electrolyte may be in the range of about 1 to about 5. Within the weight ratio range mentioned above, the improvement in the high temperature characteristics of the rechargeable lithium battery may be maximized or increased. When the weight ratio of the second compound to the first compound is less than the above range, the Coulomb effect may be abruptly reduced, and if (for example, when) the weight ratio of the second compound to the first compound is greater than the above range, a film may not be sufficiently formed on the surface of the positive electrode.

[0183] Rechargeable lithium battery

[0184] 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 type or similar battery, and a coin type or similar battery. Figures 2 to 5 middle, Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 Shows a pouch type or similar battery. Figures 2 to 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 (in which the separator 30 is provided between the positive electrode 10 and the negative electrode 20), and may further include a case 50 (in which the electrode assembly 40 is housed). The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in an electrolyte. The rechargeable lithium battery 100 may include a sealing member 60 that seals the case 50, as in Figure 2 In addition, as in Figure 3 As explained in FIG, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 4 and Figure 5 As shown in FIG, the rechargeable lithium battery 100 may include an electrode tab 70 serving as an electrical path for guiding current generated in the electrode assembly 40 outward, or may include a positive electrode tab 71 and a negative electrode tab 72.

[0185] The rechargeable lithium battery according to one or more embodiments of the present disclosure may be applied to automobiles, mobile phones, and / or any other electronic devices, but the present disclosure is not limited thereto.

[0186] A rechargeable lithium battery according to the present disclosure may include a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and the aforementioned electrolyte for a rechargeable lithium battery.

[0187] The positive electrode active material may include a lithium composite oxide represented by Chemical Formula 3.

[0188] Chemical Formula 3

[0189] Li x M 1 y M 2 z M 3 1-y-z O 2-a X a

[0190] In Chemical Formula 3, x, y, z, and a can be such that 0.5 ≤ x ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 ≤ y + z ≤ 1.

[0191] M 1 , M 2 and M 3 can each independently include at least one element selected from, such as, Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr, and La.

[0192] X can include at least one element selected from F, S, P, and Cl.

[0193] In one or more embodiments, in Chemical Formula 3, M 1 can be Ni, y can be 0.8 ≤ y ≤ 1, and z can be 0 ≤ z ≤ 0.2. In one or more embodiments, in Chemical Formula 3, M 1 can be Ni, M 2 can be Co, and M 3 can be Al. Alternatively, in Chemical Formula 3, M 1 can be Ni, M 2 can be Co, and M 3 can be Mn.

[0194] The negative electrode active material can include a carbon-based negative electrode active material, a Si-based negative electrode active material, a Sn-based negative electrode active material, and / or a combination thereof (e.g., any suitable combination).

[0195] In one or more embodiments, the negative electrode active material can include a carbon-based negative electrode active material and a Si-based negative electrode active material. For example, the carbon-based negative electrode active material can be graphite, and the Si-based negative electrode active material can be silicon nanoparticles. The weight ratio of the silicon nanoparticles to the graphite can be in the range of about 0.001 to about 20. When the graphite and the silicon nanoparticles satisfy the above combination and weight ratio, the high-temperature performance of the rechargeable lithium battery can be maximally improved.

[0196] In a rechargeable lithium battery according to one or more embodiments of the present disclosure, the electrolyte may decompose during the initial charge-discharge period to form a film with passivation ability on the surface of the positive electrode and the surface of the negative electrode, thereby improving high-temperature storage characteristics. Due to the acid (such as HF and / or PF5) generated by the thermal decomposition of the lithium salt (LiPF6, etc.) of the widely used rechargeable lithium battery, the film may degrade. This acid corrosion can dissolve transition metals from the positive electrode and increase the internal resistance of the battery due to structural changes on the surface. Therefore, due to the loss of metal elements that serve as redox (reduction and oxidation) centers, the theoretical capacity may be reduced, which may lead to a reduction in capacity. In addition, the dissolved transition metal ions may be electrodeposited on the negative electrode that reacts in the strong reduction potential range. Therefore, during electrodeposition, electrons may be consumed and the film may be destroyed, and the surface of the negative electrode may be exposed accordingly, causing additional electrolyte decomposition reactions. Therefore, there may be an increase in the surface resistance and irreversible capacity of the negative electrode, and as a result, there may be a problem of substantially continuous reduction in the capacity of the battery cell.

[0197] In the present disclosure, the -PO2F functional group of the first compound and the triazole and sulfone groups of the second compound shown above can provide unshared electron pairs to capture PF5 and stabilize LiPF6 salt, thereby removing acid generated by decomposition of the lithium salt.

[0198] In addition, the triazole group and sulfone group included in the second compound can form a film on the surface of the positive electrode to inhibit or reduce decomposition of the positive electrode active material, and thus can inhibit or reduce gas generation and transition metal dissolution caused by decomposition of the positive electrode active material.

[0199] Furthermore, the triazole group and the sulfone group included in the second compound may also have the effect of strengthening the SEI layer on the surface of the negative electrode, and thus there may be further improvement in battery life characteristics and reduction in battery internal resistance.

[0200] The positive electrode active material of the rechargeable lithium battery may include one or more of lithium cobalt oxides, lithium nickel oxides, lithium manganese oxides, lithium iron phosphate compounds, and cobalt-free nickel manganese oxides. In one or more embodiments, the positive electrode active material of the rechargeable lithium battery may include nickel, cobalt, and aluminum. In one or more embodiments, the positive electrode active material of the rechargeable lithium battery may include nickel, cobalt, and manganese.

[0201] The negative electrode active material of the rechargeable lithium battery may include a carbon-based negative electrode active material, a silicon-based negative electrode active material, or any combination thereof. In one or more embodiments, the negative electrode active material of the rechargeable lithium battery may include a carbon-based negative electrode active material and a silicon-based negative electrode active material. For example, the carbon-based negative electrode active material may be graphite, and the silicon-based negative electrode active material may be silicon nanoparticles. The weight ratio of silicon nanoparticles to graphite may be in the range of about 0.001 to about 20.

[0202] Hereinafter, embodiments of the present disclosure and comparative examples will be described. However, the embodiments described below are merely examples, and the present disclosure is not limited to the embodiments discussed herein.

[0203] Implementation Method 1

[0204] (1) Preparation of electrolyte

[0205] 1.5 M LiPF 6 was dissolved in a non-aqueous organic solvent including ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) mixed in a volume ratio of about 20:10:70, and additives were added to prepare an electrolyte.

[0206] The additive may include the first compound in an amount of 1 part by weight based on 100 parts by weight of the electrolyte and the second compound in an amount of 1 part by weight based on 100 parts by weight of the electrolyte.

[0207] The substance represented by Chemical Formula 1A and the substance represented by Chemical Formula 2A are used as the first compound and the second compound, respectively.

[0208] Chemical Formula 1A

[0209]

[0210] Chemical formula 2A

[0211]

[0212] (2) Preparation of rechargeable lithium batteries

[0213] LiNi as the positive electrode active material 0.91 Co 0.07 Al 0.02 O2, polyvinylidene fluoride as a binder, and Ketjen black as a conductive material were mixed in a weight ratio of 97:2:1, and the mixture was distributed in N-methylpyrrolidone to prepare a positive electrode active material slurry.

[0214] The positive electrode active material slurry was coated on an aluminum current collector having a thickness of 14 μm, dried at 110° C., and then pressed to prepare a positive electrode.

[0215] Artificial graphite and silicon nanoparticles mixed in a weight ratio of 93:7 as a negative electrode active material, styrene-butadiene rubber (SBR) as a binder, and carboxymethyl cellulose (CMC) as a thickener were mixed in a weight ratio of 97:1:2, and the mixture was distributed in distilled water to prepare a negative electrode active material slurry.

[0216] The negative electrode active material slurry was coated on a copper current collector with a thickness of 10 μm, dried at 100° C., and then pressed to prepare a negative electrode.

[0217] The positive electrode, the negative electrode, and a polyethylene separator having a thickness of 25 μm were assembled to prepare an electrode assembly, and an electrolyte was introduced to prepare a rechargeable lithium battery.

[0218] Implementation Method 2

[0219] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive included 1 part by weight of the first compound and 2 parts by weight of the second compound based on 100 parts by weight of the electrolyte.

[0220] Implementation 3

[0221] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive included 1 part by weight of the first compound and 3 parts by weight of the second compound based on 100 parts by weight of the electrolyte.

[0222] Implementation 4

[0223] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive included 1 part by weight of the first compound and 4 parts by weight of the second compound based on 100 parts by weight of the electrolyte.

[0224] Implementation 5

[0225] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive included 1 part by weight of the first compound and 5 parts by weight of the second compound based on 100 parts by weight of the electrolyte.

[0226] Comparative Example 1

[0227] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that no additives were added.

[0228] Comparative Example 2

[0229] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive included the first compound in an amount of 1 part by weight based on 100 parts by weight of the electrolyte, and did not include the second compound.

[0230] Comparative Example 3

[0231] An electrolyte and a rechargeable lithium battery were prepared by substantially the same method as in Embodiment 1, except that the additive did not include the first compound and included the second compound in an amount of 1 part by weight based on 100 parts by weight of the electrolyte.

[0232] Evaluation Example 1: Capacity retention under high-temperature storage

[0233] The high temperature capacity retention rate was measured to evaluate the high temperature characteristics. At room temperature (25°C), the rechargeable lithium batteries prepared in the embodiments and comparative examples were charged to SOC 100% under constant current-constant voltage (CC / CV) (0.33C, 4.25V) and 0.025C cutoff. The initial discharge capacity was measured at room temperature (25°C) under a constant current (CC) of 0.5C and a cutoff of 2.5V. The discharge capacity after storage for 60 days at 55°C was then calculated. Afterwards, the high temperature capacity retention rate (hereinafter referred to as "capacity retention rate") was calculated. The results are listed in Table 1. The high temperature capacity retention rate is calculated according to Equation 1.

[0234] Equation 1

[0235] Capacity retention (%) = (discharge capacity after storage at 55°C for 60 days / initial discharge capacity) × 100

[0236] Evaluation Example 2: Resistance Increase Rate During High-Temperature Storage

[0237] At room temperature (25° C.), the rechargeable lithium batteries prepared in the embodiments and comparative examples were charged to SOC 100% under constant current-constant voltage (CC / CV) (0.33C, 4.25V) and 0.025C cutoff conditions, and then the initial battery resistance (initial DC-IR) and the battery resistance (DC-IR) after storage at 55° C. for 60 days were measured. The resistance increase rate was calculated and the results are listed in Table 1. Among them, after discharging at 1C for 30 seconds in a fully charged state, the resistance (DC-IR) (i.e., the initial battery resistance or the battery resistance (DC-IR) after 60 days) was obtained according to Ohm's law ΔR=ΔV / ΔI, and the resistance (DC-IR) is calculated based on the difference between the current and the voltage if (when) different currents are applied. The resistance increase rate is calculated according to Equation 2.

[0238] Equation 2

[0239] Resistance increase rate (%) = [[Battery resistance after 60 days (DC-IR) / Initial battery resistance (initial DC-IR)] – 1] × 100

[0240] Evaluation Example 3: Transition Metal (Ni) Dissolution during High-Temperature Storage

[0241] The rechargeable lithium batteries prepared in the embodiments and comparative examples were charged to a SOC of 100% at 55°C, CC / CV (0.33C, 4.25V), and a 0.025C cutoff, and then stored at 55°C for 60 days. The dissolution of transition metal nickel (Ni) was measured. The results are listed in Table 1.

[0242] Table 1

[0243]

[0244] Referring to Table 1, it can be determined that, compared with the case where the electrolyte does not include any of the first compound and the second compound (Comparative Example 1), the case where the electrolyte includes only the first compound (Comparative Example 2), and the case where the electrolyte includes only the second compound (Comparative Example 3), in the case where the electrolyte includes the first compound and the second compound according to the present disclosure (Embodiment 1 to Embodiment 5), the capacity retention rate at high temperature (55°C) is excellent or appropriate. For example, it can be determined that Embodiment 1 to Embodiment 5 have excellent or appropriate improvement effects in battery life characteristics.

[0245] Still referring to Table 1, it can be confirmed that the electrolyte includes the first and second compounds according to the present disclosure (Embodiments 1 to 5) and the resistance increase rate at high temperature (55° C.) is lower than that of the electrolyte (Comparative Example 1) in which the electrolyte does not include any of the first and second compounds, the electrolyte (Comparative Example 2), and the electrolyte (Comparative Example 3). For example, it can be confirmed that Embodiments 1 to 5 have an excellent or appropriate reduction effect in the resistance increase rate.

[0246] Referring back to Table 1, it can be determined that the amount of transition metal (Ni) dissolved at high temperature (55° C.) is lower in the case where the electrolyte includes the first and second compounds according to the present disclosure (Embodiments 1 to 5) than in the case where the electrolyte does not include any of the first and second compounds (Comparative Example 1), the case where the electrolyte includes only the first compound (Comparative Example 2), and the case where the electrolyte includes only the second compound (Comparative Example 3). For example, it can be determined that Embodiments 1 to 5 have excellent or appropriate inhibitory effects on the amount of transition metal dissolved.

[0247] The electrolyte for a rechargeable lithium battery according to one or more embodiments can improve the lifespan characteristics of the rechargeable lithium battery and reduce its internal resistance. These effects can become significant at high temperatures.

[0248] The battery management system (BMS) device and / or any other related devices or components according to the embodiments of the present disclosure described herein may be implemented using any appropriate hardware, firmware (e.g., an application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, one or more appropriate components of the device may be formed on a single integrated circuit (IC) chip or on separate IC chips. Further, one or more appropriate components may be implemented on a flexible printed circuit film, a tape carrier package (TCP), or a printed circuit board (PCB), or formed on a single substrate. Further, one or more appropriate components of the device may 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 one or more appropriate functions described herein. The computer program instructions are stored in a memory, which may be implemented in the computing device using standard storage devices (such as, for example, random access memory (RAM)). The computer program instructions may also be stored in other non-transitory computer-readable media (such as, for example, CD-ROMs, flash drives, etc.). Furthermore, those skilled in the art will recognize that, without departing from the scope of the present disclosure, the functionality of one or more appropriate computing devices may be combined or integrated into a single computing device, or the functionality of a dedicated computing device may be distributed across one or more other computing devices.

[0249] Although the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments and is intended to cover one or more suitable modifications and equivalent arrangements included within the spirit and scope of the claims and their equivalents. Therefore, the foregoing embodiments are to be understood as examples and not as limiting the present disclosure in any way.

Claims

1. An electrolyte, comprising: A non-aqueous organic solvent; A lithium salt; And An additive, wherein the additive comprises a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, Chemical Formula 1 wherein in Chemical Formula 1, X 1 is a fluoro group, a chloro group, a bromo group or an iodo group, R 1 ~R 6 are each independently hydrogen, cyano, 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 n is an integer of 0 or 1, Chemical Formula 2 wherein in Chemical Formula 2, L 2A and L 2B Each is independently a single bond, a substituted or unsubstituted C1-C5 alkylene group, a substituted or unsubstituted C2-C5 alkenylene group, a substituted or unsubstituted C2-C5 alkynylene group, or a substituted or unsubstituted C6-C20 arylene group, A and B are each independently a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C2-C20 heteroaryl group, and at least one selected from A and B is a group represented by Chemical Formula A, Chemical Formula A wherein in Chemical Formula A, R 7 and R 8 are each independently hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl, wherein the term "substituted" means that at least one hydrogen of the substituent is replaced by deuterium, halogen, hydroxy, amino, C1-C30 amine, 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, or nitrile, and wherein the electrolyte is used in a rechargeable lithium battery.

2. The electrolyte according to claim 1, wherein based on 100 parts by weight of the electrolyte for the rechargeable lithium battery, the amount of the first compound is 0.2 parts by weight to 5.0 parts by weight.

3. The electrolyte according to claim 1, wherein based on 100 parts by weight of the electrolyte for the rechargeable lithium battery, the amount of the second compound is 1 part by weight to 5 parts by weight.

4. The electrolyte according to claim 1, wherein based on 100 parts by weight of the electrolyte for the rechargeable lithium battery, the amount of the additive is 1.2 parts by weight to 10 parts by weight.

5. The electrolyte according to claim 1, wherein the weight ratio of the second compound to the first compound in the additive is in the range of 0.2 to 25.

6. The electrolyte according to claim 1, wherein the weight ratio of the second compound to the first compound in the additive is in the range of 1 to 5.

7. The electrolyte according to claim 1, wherein Chemical Formula 1 is represented by at least one of Chemical Formula 1-1 and Chemical Formula 1-2, Chemical Formula 1-1 Chemical Formula 1-2 In Chemical Formula 1-1 and Chemical Formula 1-2, X 1 is a fluoro, chloro, bromo or iodo group, and R 1 ~R 6 Each is independently hydrogen, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C2-C10 alkenyl, or substituted or unsubstituted C2-C10 alkynyl.

8. The electrolyte according to claim 7, wherein R in Chemical Formula 1-1 3 and R 4 are each hydrogen, and Selected from R 5 and R 6 At least one of them is a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 alkoxy group, a substituted or unsubstituted C2-C10 alkenyl group, or a substituted or unsubstituted C2-C10 alkynyl group.

9. The electrolyte according to claim 1, wherein the first compound is any one of the compounds listed in Group 1, Group 1 10. The electrolyte according to claim 1, wherein the 2A and L 2B At least one of them is a substituted or unsubstituted C1-C5 alkylene group.

11. The electrolyte of claim 1, wherein the electrolyte is selected from L 2A and L 2B At least one of them is a substituted or unsubstituted C2-C5 alkylene group.

12. The electrolyte according to claim 1, wherein Chemical Formula 2 is represented by Chemical Formula 2-1, Chemical Formula 2-1 and wherein in Chemical Formula 2-1, L 1 and L 2 are each independently a substituted or unsubstituted C2-C5 alkylene group, and R 21A 、R 21B 、R 21C and R 21D Each is independently hydrogen, halogen, substituted or unsubstituted C1-C10 alkyl, or substituted or unsubstituted C3-C10 cycloalkyl.

13. The electrolyte according to claim 1, wherein the second compound is any one of the compounds listed in Group 2, Group 2 14. A rechargeable lithium battery, comprising: A positive electrode, comprising a positive electrode active material; A negative electrode, comprising a negative electrode active material; And The electrolyte according to any one of claims 1 to 13.

15. The rechargeable lithium battery according to claim 14, wherein the positive electrode active material comprises a lithium composite oxide represented by Chemical Formula 3, Chemical Formula 3 Li x M 1 y M 2 z M 3 1-y-z O 2-a X a and wherein in Chemical Formula 3, 0.5 ≤ x ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 ≤ y + z ≤ 1, M 1 、M 2 and M 3 Each independently comprises at least one element selected from Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr and La, and X comprises at least one element selected from F, S, P and Cl.

16. The rechargeable lithium battery of claim 15, wherein in Chemical Formula 3, M 1 is Ni, 0.8≤y≤1, and 0≤z≤0.

2. 17 . The rechargeable lithium battery of claim 14 , 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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