Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same

Abstract

The invention relates to an electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the same. 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 borate lithium salt compound. The detailed description of the chemical formula 1 is disclosed in the specification. Chemical formula 1

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0113637, filed with the Korean Intellectual Property Office on August 23, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

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

[0004] Recently, with the rapid proliferation of battery-powered electronic products and / or devices (such as mobile phones, laptops, electric vehicles, etc.), the demand for batteries with relatively high energy density and high capacity (e.g., rechargeable batteries) has increased significantly. Consequently, extensive research has been conducted to enhance the performance of such rechargeable batteries (e.g., rechargeable lithium batteries).

[0005] A rechargeable lithium battery includes a positive electrode, a negative electrode, and an electrolyte. Both the positive and negative electrodes (e.g., each) include active materials in which lithium ions can be inserted and extracted (i.e., the active materials are capable of inserting and extracting lithium ions). For example, if lithium ions are inserted and extracted, the rechargeable lithium battery generates electrical energy through oxidation and reduction reactions. Summary of the Invention

[0006] One or more aspects of this disclosure relate to electrolytes for rechargeable lithium batteries that exhibit superior or adequate suppression of gas generation and resistance increase during high-temperature storage (e.g., effective suppression of gas generation and resistance increase during high-temperature storage).

[0007] One or more aspects of this disclosure relate to electrolytes for rechargeable lithium batteries having enhanced (e.g., improved) cycle life characteristics.

[0008] One or more aspects of this disclosure relate to rechargeable lithium batteries that include the electrolyte discussed herein.

[0009] Other 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 practicing the embodiments presented in this disclosure.

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

[0011] Additives may include: a first compound represented by chemical formula 1; and borate-based lithium salt compounds.

[0012] Chemical Formula 1

[0013]

[0014] In chemical formula 1,

[0015] R1 may be the same or different, and each may independently be hydrogen, halogenated, C1-C10 alkyl, or isocyanate group, wherein at least one R1 is an isocyanate group.

[0016] R2 may be the same or different, and each may independently be hydrogen, halogenated, C1-C10 alkyl, or isocyanate group, wherein at least one R2 is an isocyanate group.

[0017] R3 can be the same or different, and can each independently be a hydrogen or cyclohexyl isocyanate residue, and

[0018] n can be an integer from 1 to 10 (for example, n can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10).

[0019] According to one or more embodiments of this disclosure, a rechargeable lithium battery may include: a positive electrode comprising a positive electrode active material; a negative electrode comprising a negative electrode active material; and the aforementioned electrolyte for a rechargeable lithium battery. Attached Figure Description

[0020] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is provided.

[0021] Figures 2-5 The diagrams illustrate rechargeable lithium batteries according to one or more embodiments of the present disclosure. Detailed Implementation

[0022] To fully understand the layout and effects of this disclosure, one or more embodiments of this disclosure will be described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the exemplary embodiments described below and can be implemented in one or more suitable forms. Rather, exemplary embodiments are provided merely to disclose this disclosure and to allow those skilled in the art to fully understand its scope.

[0023] In this description, it will be understood that if (for example, when) an element is referred to as being on another element, then the element may be directly on the other element, or an intermediary element may exist between the two. In the accompanying drawings, the thickness of some components has been enlarged for effective explanation of the technical content. The same reference numerals refer to the same elements throughout, and their repeated description is not required in the specification.

[0024] Unless otherwise specifically stated in this description, singular expressions may include plural expressions. For example, unless otherwise specifically indicated, the phrase “A or B” may indicate “A but not B,” “B but not A,” and “A and B.” The terms “comprise / include,” “comprises / includes,” “comprising / including,” “have,” “having,” and / or “has” as used in this description are intended to indicate the presence of a specific component, feature, aspect, quantity, step (e.g., action or task), element, and / or combination thereof (e.g., any suitable combination thereof). However, the use of these terms does not preclude or exclude the possibility, presence, and / or addition of one or more other components, features, aspects, quantities, steps (e.g., action or task), elements, and / or combinations thereof (e.g., any suitable combination thereof). Furthermore, the terms "comprise(s) / comprising," "include(s) / including," "have / has / having," or other similar terms include or support the terms "composed of," and "substantially composed of," indicating the presence of the described features, integers, steps, operations, elements, and / or components, and the absence or substantial absence of other features, integers, steps, operations, elements, components, and / or groups thereof. Moreover, in the context, "substantially composed of" indicates that any additional component will not substantially affect the chemical, physical, optical, or electrical properties of the target portion.

[0025] In this description, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0026] In one or more embodiments, if (e.g., when) viewed from a plan view, the term "layer" herein includes not only shapes formed or provided over the entire surface, but also shapes formed or provided on a portion of the surface.

[0027] It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe one or more appropriate elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one element, component, area, layer, or portion from another. Therefore, without departing from the teachings set forth herein, a first element, component, area, layer, or portion described herein may be referred to as a second element, component, area, layer, or portion.

[0028] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated items. Expressions such as “at least one of…”, “one of…”, and “selected from…” modify the entire list of elements, but not individual elements of the list, if (e.g., before / after) a list of elements. For example, expressions “at least one of a to c” and “at least one of a, b, and / or c” can 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.

[0029] Spatial relative terms (such as "below," "below," "down," "above," "upper," etc.) may be used herein to readily describe the relationship between one element or feature and another. It will be understood that, in addition to the orientations illustrated in the figures, spatial relative terms are intended to encompass different orientations of the device in use or operation. For example, if (e.g., when) the device in the figures is flipped, an element described as "below" or "below" of other elements or features will be oriented "above" of those other elements or features. Thus, the example term "below" can encompass both above and below orientations (e.g., simultaneously). The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative terms used herein may be interpreted accordingly.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Unless otherwise specified, all terms used herein (including chemical, technical, and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having the meaning consistent with their meaning in the context of the relevant technology and this disclosure, and will not be interpreted in an ideal or overly formal sense.

[0031] Example embodiments are described herein with reference to cross-sectional views illustrating preferred embodiments. As such, variations in the illustrated shape are contemplated due to, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be construed as limited to the specific shape of the regions illustrated herein, but rather include, for example, shape deviations resulting from manufacturing processes. For example, regions illustrated or described as flat may generally have rough and / or non-linear characteristics. Furthermore, illustrated sharp corners may be rounded. Therefore, the regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0032] The term “may” is to be understood as “one or more embodiments of this disclosure.” Some of these embodiments include the described elements, and some embodiments do not include the elements and / or include alternative elements. Similarly, alternative language such as “or” refers to “one or more embodiments of this disclosure,” each including the corresponding enumerated items.

[0033] In the context of this application, and unless otherwise specified, the terms “use,” “using,” and “used” are to be regarded as synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively.

[0034] As used herein, the term "particle size" refers to the average diameter of the particle if (e.g., when) the particle is spherical, and the term "particle size" refers to the average length of the major axis of the particle if (e.g., when) the particle is non-spherical. For example, unless otherwise specifically defined in this description, particle size may refer to the average particle size. For instance, particle size indicates the average particle size (D) representing approximately 50% by volume of the cumulative volume in the particle size distribution. 50 Average particle size (D) 50 The particle size distribution (D) can be measured using methods well known to those skilled in the art, such as by a particle size analyzer, transmission electron microscopy (TEM) images, or scanning electron microscopy (SEM) images. In one or more embodiments, a dynamic light scattering measurement device can be used for data analysis to count the number of particles in each particle size range, from which the average particle size (D) can then be calculated. 50 ) value. Unless otherwise specified, the average particle size (D) 50 The average particle size (D) can refer to the diameter of particles that constitute approximately 50% of the total volume in the particle size distribution. In contrast, laser scattering methods can be used to measure the average particle size (D). 50In the laser scattering method, target particles are distributed in a dispersion solvent and introduced into a laser scattering particle measuring device (e.g., the MT3000, commercially available from Microtrac Ltd.). The particles are irradiated with ultrasound at 28 kHz at a power of 60 W. The average particle size (D) is then calculated in the measuring device based on a 50% particle size distribution. 50 As used herein, unless otherwise specified, the average particle size (D) is... 50 The diameter refers to the diameter of particles that constitute 50% of the total volume in a particle size distribution obtained by randomly measuring the size (diameter or major axis length) of approximately 20 particles in a scanning electron microscope image.

[0035] In this description, unless otherwise specified separately, the term "substitution" may mean that at least one hydrogen atom of a substituent or compound is substituted by: deuterium, halogen, hydroxyl, amino, C1-C30 amino, nitro, C1-C40 silyl, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C20 alkoxy, C1-C10 fluoroalkyl, cyano, and / or combinations thereof (e.g., any suitable combination thereof).

[0036] More specifically, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: deuterium, halogroup, C1-C30 alkyl, C1-C10 alkylsilyl, C6-C30 arylsilyl, C3-C30 cycloalkyl, C3-C30 heterocycloalkyl, C6-C30 aryl, C2-C30 heteroaryl, C1-C10 fluoroalkyl, or cyano. For example, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: deuterium, halogroup, C1-C20 alkyl, C6-C30 aryl, C1-C10 fluoroalkyl, or cyano. In one or more embodiments, the term "substitution" may refer to at least one hydrogen atom of a substituent or compound being substituted with: deuterium, halogroup, C1-C5 alkyl, C6-C18 aryl, C1-C5 fluoroalkyl, or cyano. For example, the term "substitution" can refer to the substitution of at least one hydrogen atom of a substituent or compound by the following: deuterium, cyano, halo, methyl, ethyl, propyl, butyl, phenyl, biphenyl, terphenyl, trifluoromethyl, or naphthyl.

[0037] Figure 1 Description

[0038] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is provided. References Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0039] The positive electrode 10 and the negative electrode 20 may be spaced apart and / or separated from each other across the diaphragm 30 (e.g., spaced apart and / or separated). The diaphragm 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the diaphragm 30 may be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20, and the diaphragm 30 may be immersed in the electrolyte ELL.

[0040] The electrolyte ELL serves as a medium for transferring lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move through the separator 30 toward one of the positive electrode 10 and the negative electrode 20.

[0041] Positive electrode 10

[0042] 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 (hereinafter referred to as the "positive electrode active material layer") 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 (e.g., an electronic conductor).

[0043] For example, the positive electrode 10 may further include components that can be used as a sacrificial positive electrode.

[0044] The amount of positive electrode active material relative to 100 wt% of the positive electrode active material layer AML1 can be about 90 wt% to about 99 wt%. The amount of each of the binder and conductive material relative to 100 wt% of the positive electrode active material layer AML1 can be about 0.5 wt% to about 5 wt%.

[0045] The binder can be used to improve the adhesion between the positive electrode active material particles and also to improve the adhesion between the positive electrode active material and the positive electrode current collector COL1. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin and / or nylon, but this disclosure is not limited thereto.

[0046] Conductive materials can be used to provide electrode conductivity, and any suitable conductive material that does not cause chemical changes in the battery can be used as a conductive material. Conductive materials may include: carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers and / or carbon nanotubes); metal powders or metal fibers containing (for example, selected from) at least one of copper, nickel, aluminum and silver; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (for example, any suitable mixture thereof).

[0047] Aluminum (Al) foil can be used as the positive electrode current collector COL1, but this disclosure is not limited thereto.

[0048] Positive electrode active material

[0049] The positive electrode active material in the positive electrode active material layer AML1 may include compounds that can reversibly insert and deintercalate lithium (e.g., lithiated intercalation compounds). For example, the positive electrode active material may include: a composite oxide comprising lithium and at least one metal selected from cobalt, manganese, nickel and / or combinations thereof (e.g., any suitable combination thereof).

[0050] Composite oxides may include lithium transition metal composite oxides, such as lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free nickel manganese oxides and / or combinations thereof (e.g., any suitable combination thereof).

[0051] For example, the positive electrode active material may include a compound represented by (for example, selected from) one of the following chemical formulas: Li a A 1-b X b O 2-c D c (where 0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (where 0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L 1 d G e O2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO4 (where 0.90 ≤ a ≤ 1.8 and 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (where 0≤f≤2); and Li a FePO4 (where 0.90≤a≤1.8).

[0052] In the chemical formulas described herein, A may be Ni, Co, Mn and / or combinations thereof (e.g., any suitable combination thereof), X may be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and / or combinations thereof (e.g., any suitable combination thereof), D may be O, F, S, P and / or combinations thereof (e.g., any suitable combination thereof), G may be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and / or combinations thereof (e.g., any suitable combination thereof), and L 1 It can be Mn, Al and / or combinations thereof (e.g., any suitable combination thereof).

[0053] For example, the positive electrode active material can be a high-nickel positive electrode active material, having a nickel content 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% relative to 100 mol% of lithium-free metal in a lithium transition metal complex oxide (high-nickel positive electrode active material). High-nickel positive electrode active materials can achieve high capacity and are therefore suitable for applications in high-capacity and high-density rechargeable lithium batteries.

[0054] negative electrode 20

[0055] 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 (hereinafter referred to as the "negative electrode active material layer") 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 (e.g., an electronic conductor).

[0056] For example, relative to 100 wt% of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include about 90 wt% to about 99.5 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.

[0057] The binder can be used to improve the adhesion between the negative electrode active material particles and also to improve the adhesion between the negative electrode active material and the negative electrode current collector COL2. The binder may include non-aqueous binders, aqueous binders, dry binders and / or combinations thereof (e.g., any suitable combination thereof).

[0058] Non-aqueous adhesives may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide and / or combinations thereof (e.g., any suitable combination thereof).

[0059] Waterborne adhesives may include styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomers, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and / or combinations thereof (e.g., any suitable combination thereof).

[0060] If (for example, when) an aqueous binder is used as a binder in the negative electrode active material layer AML2, it may further include a cellulose compound capable of providing viscosity. 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.

[0061] Dry adhesives may include fibrous polymeric materials, such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide and / or combinations thereof (e.g., any suitable combination thereof).

[0062] Conductive materials can be used to provide electrode conductivity, and any suitable conductive material that does not cause chemical changes in the battery can be used as a conductive material. For example, conductive materials may include: carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers and / or carbon nanotubes); metal powders or metal fibers including (for example, selected from) at least one of copper, nickel, aluminum and silver; conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (for example, any suitable mixture thereof).

[0063] The negative electrode current collector COL2 may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and / or combinations thereof (e.g., any suitable combination thereof).

[0064] Negative electrode active material

[0065] The negative electrode active material in the negative electrode active material layer AML2 may include materials that can reversibly insert and deintercalate lithium ions, lithium metal, lithium metal alloys, materials that can be doped and dedoped with lithium, and / or transition metal oxides.

[0066] Materials capable of reversibly inserting and deintercalating lithium ions may include carbon-based negative electrode active materials (e.g., crystalline carbon, amorphous carbon, and / or combinations thereof (e.g., any suitable combination thereof)). For example, crystalline carbon may include graphite (such as amorphous, flake, sheet, spherical, and / or fibrous natural graphite and / or artificial graphite), and amorphous carbon may include soft carbon, hard carbon, mesophase pitch carbon, and / or calcined coke.

[0067] Lithium metal alloys may include alloys of lithium with at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0068] Materials that can be doped and dedoped with lithium can include Si-based or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, silicon-carbon composites, and SiO₂.x (where 0 < x ≤ 2), Si-Q alloy (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 a combination thereof (e.g., any suitable combination thereof)) and / or a combination thereof (e.g., any suitable combination thereof). The Sn-based negative electrode active material may include Sn, SiO y (where 0 < y ≤ 2, e.g., SnO2), Sn-based alloy, and a combination thereof.

[0069] 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) in which primary silicon particles are assembled 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.

[0070] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include: a core including crystalline carbon and silicon particles, and may also include an amorphous carbon coating (e.g., coal tar pitch) located on the surface of the core.

[0071] 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.

[0072] Separator 30

[0073] Depending on the type (category) 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 at least one (e.g., a plurality) selected from polyethylene, polypropylene, and polyvinylidene fluoride, and may have a multilayer separator such as a polyethylene / polypropylene bilayer separator, a polyethylene / polypropylene / polyethylene trilayer separator, and / or a polypropylene / polyethylene / polypropylene trilayer separator.

[0074] The separator 30 may include a porous substrate and a coating located on the surface or side (e.g., one surface or (e.g., two) opposite surfaces) of the porous substrate, and the coating may include an organic material, an inorganic material, and / or a combination thereof (e.g., any suitable combination thereof).

[0075] The porous substrate may be a polymer layer comprising one or more copolymers or mixtures selected from the following: polyolefins (such as polyethylene and / or polypropylene), polyesters (such as polyethylene terephthalate and / or polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber and / or Teflon (e.g., polytetrafluoroethylene).

[0076] Organic materials may include polyvinylidene fluoride copolymers and / or (meth)acrylic acid copolymers.

[0077] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and / or combinations thereof (e.g., any suitable combination thereof), but this disclosure is not limited thereto.

[0078] Organic and inorganic materials can be mixed in a single coating or exist as a stack of coatings containing organic materials and coatings containing inorganic materials.

[0079] Electrolyte ELL

[0080] Electrolytes (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0081] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery.

[0082] Non-aqueous organic solvents may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents and / or combinations thereof (e.g., any suitable combination thereof).

[0083] Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and / or butyl carbonate (BC).

[0084] Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, valproic acid lactone, and / or caprolactone.

[0085] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and / or tetrahydrofuran. Ketone solvents may include cyclohexanone. Alcohol solvents may include ethanol and / or isopropanol, and aprotic solvents may include nitrile (such as R-CN, where R is a hydrocarbon group having a C2-C20 straight-chain, branched, or cyclic structure, and may include double bonds, aromatic rings, or ether bonds); amides (such as dimethylformamide); dioxolane (such as 1,3-dioxolane and / or 1,4-dioxolane); and / or sulfolane.

[0086] Non-aqueous organic solvents can be used alone or in mixtures of two or more substances.

[0087] For example, if (e.g., when) a carbonate solvent is used, cyclic carbonates and chain carbonates can be mixed and used, and cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0088] Lithium salts are materials that can be dissolved in non-aqueous organic solvents and are used as a source of lithium ions in batteries, playing a role in ensuring the basic operation of rechargeable lithium batteries and facilitating the movement of lithium ions between the positive and negative electrodes. Lithium salts may include, for example, those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N, lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, and LiN(C x F 2x+ 1SO2)(C y F 2y+1 SO2 (for example, where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, and lithium difluorobis(oxalate)phosphate (LiDFOP) are at least one of these.

[0089] electrolyte

[0090] The following description will focus on electrolytes for rechargeable lithium batteries according to one or more embodiments of the present disclosure.

[0091] Electrolytes for rechargeable lithium batteries according to one or more embodiments of this disclosure may include non-aqueous organic solvents, lithium salts, and additives.

[0092] The non-aqueous organic solvent may be a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and / or dimethyl carbonate (DMC). For example, the amount of ethylene carbonate (EC) included relative to the total volume of the non-aqueous organic solvent may be from about 10 vol% to about 30 vol%. The amount of ethyl methyl carbonate (EMC) included relative to the total volume of the non-aqueous organic solvent may be from about 20 vol% to about 70 vol%. The amount of dimethyl carbonate (DMC) included relative to the total volume of the non-aqueous organic solvent may be from about 20 vol% to about 70 vol%.

[0093] The lithium salt may include 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), and LiC4F9SO3. In one or more embodiments, the lithium salt may include LiPF6.

[0094] The lithium salt can have a concentration from about 0.1 molar concentration (M) to about 2.0 M. For example, the lithium salt can have a concentration equal to or greater than about 0.5 M or equal to or greater than about 1.0 M. The lithium salt can 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. For example, the lithium salt can have a concentration of about 1.5 M. If (for example, when) the lithium salt has a concentration within the aforementioned range, the electrolyte can suitably or appropriately maintain its conductivity and viscosity.

[0095] The additives according to one or more embodiments of this disclosure may include a first compound represented by chemical formula 1 and a borate lithium salt compound.

[0096] The first compound can be represented by chemical formula 1.

[0097] Chemical Formula 1

[0098]

[0099] In chemical formula 1,

[0100] R1 may be the same or different, and each may be independently hydrogen, halogen, C1-C10 alkyl or isocyanate group. At least one of R1 may be an isocyanate group.

[0101] R2 may be the same or different, and each may be independently hydrogen, halogen, C1-C10 alkyl or isocyanate group, and at least one of R2 may be an isocyanate group.

[0102] R3 can be the same or different, and can each be a hydrogen or cyclohexyl isocyanate functional group (e.g., residue).

[0103] The subscript n can be an integer from 1 to 10.

[0104] In one or more embodiments, the first compound may be represented by chemical formula 1-1.

[0105] Chemical Formula 1-1

[0106]

[0107] In chemical formula 1-1,

[0108] R1 can be the same or different, and each can be independently hydrogen, halogen, C1-C10 alkyl or isocyanate group. At least one R1 can be an isocyanate group.

[0109] R2 can be the same or different, and each can be independently hydrogen, halogen, C1-C10 alkyl or isocyanate group. At least one R2 can be an isocyanate group.

[0110] In one or more embodiments, the first compound may be represented by chemical formulas 1-2.

[0111] Chemical formula 1-2

[0112]

[0113] In chemical formulas 1-2,

[0114] R1 can be the same or different, and each can be hydrogen, halogroup or C1 to C10 alkyl group independently.

[0115] R2 can be the same or different, and each can be hydrogen, halogroup or C1 to C10 alkyl group independently.

[0116] In one or more embodiments, the first compound may be represented by chemical formula 1-2-1.

[0117] Chemical formula 1-2-1

[0118]

[0119] The first compound may include an alicyclic diisocyanate compound. The first compound may have a cyclic structure and excellent or suitable chemical resistance to stably form a film on the surfaces of the positive and negative electrodes. Therefore, by including the first compound in the additive, lithium dendrite formation can be prevented or reduced, and side reactions of lithium metal released from the positive electrode can be suppressed or reduced.

[0120] Some salt products formed from lithium salts (e.g., LiPF6) or (discussed in more detail) borate lithium salt compounds can react with moisture to produce byproducts, which can cause swelling or one or more suitable side reactions. A first compound can react with moisture to produce an amine, which can then react with any existing (e.g., any remaining) isocyanate to form a polyurea. The polyurea can be coated or filled onto the surfaces of the positive and negative electrodes to minimize or reduce the effects of moisture and to suppress or reduce side reactions that may occur on the surfaces of the positive and negative electrodes.

[0121] The amount of the first compound included relative to the total weight of the electrolyte can be from about 0.01 wt% to about 5 wt%. For example, the amount of the first compound included relative to the total weight of the electrolyte can be equal to or greater than about 0.1 wt% or equal to or greater than about 0.5 wt%. The amount of the first compound included relative to the total weight of the electrolyte can be equal to or less than about 3 wt% or equal to or less than about 2 wt%. In one or more embodiments, the amount of the first compound included relative to the total weight of the electrolyte can be from about 0.1 wt% to about 3 wt%.

[0122] If, for example, the amount of the first compound is less than the lower limit of the aforementioned range, the effect of suppressing or reducing moisture in the battery cell may be insignificant. If, for example, the amount of the first compound is greater than the upper limit of the aforementioned range, the expansion improvement effect and high-temperature storage characteristics may be reduced. In this sense, if, for example, the amount of the first compound falls within the aforementioned range, gas generation and the increase in battery internal resistance can be effectively suppressed or reduced, and battery cycle life characteristics can be improved.

[0123] Borate ester lithium salt compounds can be represented by chemical formula 2.

[0124] Chemical formula 2

[0125]

[0126] In chemical formula 2,

[0127] X can be a halogen or a C1-C10 haloalkyl group.

[0128] m1 can be 1 or 2.

[0129] If (for example, when) m1 is 1, then m2 can be 2.

[0130] If (for example, when) m1 is 2, then m2 can be 0.

[0131] According to one or more embodiments, the borate ester lithium salt compound may include at least one selected from lithium bis(oxalate)borate (LiBOB) and lithium difluoro(oxalate)borate (LiDFOB).

[0132] Boronate lithium salt compounds can serve as amphoteric lithium salt additives, which help replenish and absorb lithium at the positive and negative electrodes, thereby promoting lithium insertion into and extraction from the positive and negative electrode active materials and improving the charge / discharge characteristics of the battery.

[0133] In one or more embodiments, the borate ester lithium salt compound may be lithium bis(oxalate)borate (LiBOB).

[0134] Lithium bis(oxalate)borate (LiBOB) can electrochemically decompose at the interface between the positive and negative electrodes to form a stable borate (BO) film. Therefore, if (for example) a borate lithium salt compound is used in conjunction with the first compound, a more robust film can be formed.

[0135] In one or more embodiments, the borate ester lithium salt compound may be lithium difluoro(oxalate)borate (LiDFOB).

[0136] Because lithium difluoro(oxalate)borate (LiDFOB) contains halogen elements (such as fluorine), a robust film composed of LiF and borate esters (BO) organic materials can be formed on the positive and negative electrodes.

[0137] The amount of borate ester lithium salt compound (e.g., LiBOB or LiDFOB) included may be from about 0.01 wt% to about 5 wt% relative to the total weight of the electrolyte used in the rechargeable lithium battery. For example, the amount of borate ester lithium salt compound included may be 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 amount of the first compound included may be equal to or less than about 3 wt% or equal to or less than about 2 wt% relative to the total weight of the electrolyte. In one or more embodiments, the amount of borate ester lithium salt compound included may be from about 0.1 wt% to about 3 wt% relative to the total weight of the electrolyte used in the rechargeable lithium battery.

[0138] If, for example, the amount of borate lithium salt compound is less than the lower limit of the aforementioned range, a sufficient film may not form on the positive and negative electrodes. If, for example, the amount of borate lithium salt compound is greater than the upper limit of the aforementioned range, the viscosity and surface resistance of the positive and negative electrodes will increase, leading to problems in ensuring the performance of the battery cells, such as capacity retention and cycle life. For example, if, for example, the amount of borate lithium salt compound falls within the aforementioned range, a film with low surface resistance and excellent or adequate thermal stability can be formed to effectively suppress or reduce electrolyte decomposition reactions.

[0139] According to one or more embodiments, the amount of additives comprising the first compound and borate lithium salt compounds may be from about 0.1 wt% to about 10 wt% relative to the total weight of the electrolyte for a rechargeable lithium battery. If (for example, when) the amount of additives falls within the aforementioned range, not only can the effect of improving battery resistance and gas generation problems be maximized or increased, but side reactions caused by excessive amounts of additives can also be prevented or reduced.

[0140] According to one or more embodiments, the weight ratio of the first compound to the borate lithium salt compound (e.g., the weight ratio of the included first compound to the borate lithium salt compound) can be about 10:1 to about 1:10. For example, the weight ratio of the included first compound to the borate lithium salt compound can be about 5:1 to about 1:5 or about 3:1 to about 1:3. If (e.g., when) the weight ratio of the first compound to the borate lithium salt compound falls within the aforementioned range, an oxide film and a reduction film can be formed on the positive electrode and the negative electrode, respectively, thereby realizing a rechargeable lithium battery that exhibits enhanced gas generation and suppression of resistance increase during high-temperature storage, and also improves cycle characteristics at room temperature and high temperature.

[0141] A synergistic effect can occur when the first compound and the borate lithium salt compound are used in combination. For example, if the additive includes both the first compound and the borate lithium salt compound, a robust film can be formed on the surfaces of the positive and negative electrodes compared to using each compound alone as an additive. In summary, the combination of the compounds (i.e., the first compound and the borate lithium salt compound) can prevent or reduce electrolyte decomposition and the resulting electrode decomposition reactions, contributing to improved high-temperature storage characteristics and cycle life characteristics of the battery.

[0142] In summary, the electrolyte for rechargeable lithium batteries may include a non-aqueous organic solvent, lithium salt, and additives. The solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), each component having a specific volume percentage to enhance performance. Lithium salts, including compounds similar to LiPF6, may be present at a concentration ranging from 0.1 to 2.0 mol to maintain the electrolyte's conductivity and viscosity.

[0143] The additives include a first compound represented by the chemical formulas described above and a borate lithium salt compound (such as lithium bis(oxalate)borate (LiBOB) and / or lithium difluoro(oxalate)borate (LiDFOB)). These additives help form a stable film on the electrode surface, reduce side reactions, and improve battery performance. The first compound reacts with moisture to form a polyurea, reducing the effects of moisture and suppressing side reactions on the electrode. The amount of the included first compound can range from 0.01 wt% to 5 wt% of the total electrolyte weight, enhancing the effectiveness of the additives in reducing gas generation and improving battery cycle life characteristics.

[0144] Borate ester lithium salt compounds help form a stable film on the electrode, enhancing charge / discharge characteristics. This compound is also included in a specific weight percentage to balance film formation and maintain cell performance. When used together, the first compound and the borate ester lithium salt compound have a synergistic effect, forming a robust film that prevents electrolyte decomposition and improves the battery's high-temperature storage and cycle life performance.

[0145] Overall, this combination of non-aqueous organic solvents, lithium salts, and additives aims to enhance the performance and lifespan of rechargeable lithium batteries by maintaining optimal conductivity, reducing side reactions, and forming a protective film on the electrodes.

[0146] Rechargeable lithium batteries

[0147] Based on their shape, rechargeable lithium batteries can be classified into cylindrical, prismatic, pouch, and coin-shaped types. Figures 2-5 Each illustration shows a simplified diagram of a rechargeable lithium battery according to one or more embodiments. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 A pouch-type (or similar) battery is shown. (Reference) Figures 2-5 The rechargeable lithium battery 100 may include an electrode assembly 40 (with a separator 30 inserted between a positive electrode 10 and a negative electrode 20), and may also include a housing 50 (containing the electrode assembly 40). The positive electrode 10, negative electrode 20, and separator 30 may be immersed in an electrolyte. Figure 2 The text explains that the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. For example, such as... Figure 3 The text explains that the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 4 and Figure 5As shown, the rechargeable lithium battery 100 may include electrode tabs (e.g., at least one electrode tab) 70, or a positive electrode tab 71 and a negative electrode tab 72, and the electrode tabs 70, the positive electrode tab 71, and the negative electrode tab 72 serve as circuit paths for guiding the current generated in the electrode assembly 40 to the outside.

[0148] A rechargeable lithium battery according to one or more embodiments of the present disclosure may include: a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and an electrolyte for the rechargeable lithium battery described above.

[0149] The positive electrode active material may include a compound (e.g., a lithiated insertion compound) that reversibly inserts and extracts lithium.

[0150] For example, the positive electrode active material may include: at least one composite oxide including lithium and a metal selected from cobalt, manganese, nickel, and / or a combination thereof (e.g., any suitable combination thereof).

[0151] The positive electrode active material may include, for example, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate compound, cobalt-free nickel manganese oxide, and / or a combination thereof (e.g., any suitable combination thereof).

[0152] In one or more embodiments, the positive electrode active material may include at least one selected from lithium iron phosphate compounds (LFP), lithium cobalt oxides (LCO), lithium nickel cobalt aluminum oxides (NCA), and lithium nickel cobalt manganese oxides (NCM).

[0153] If (e.g., when) an electrolyte according to one or more embodiments of the present disclosure is used in combination with a positive electrode coated with a positive electrode active material, gas generation and an increase in battery resistance during high-temperature storage can be suppressed or reduced, so as to improve the high-temperature stability of the battery and enhance the cycle life characteristics at high temperature and room temperature.

[0154] The negative electrode active material may 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 thereof). In one or more embodiments, the negative electrode active material may be a Si-based negative electrode active material.

[0155] The Si-based negative electrode active material may include: a core including silicon-based particles (Si-based particles) and a coating including amorphous carbon. The silicon-based particles may include a silicon-carbon composite, SiO x (0 < x ≤ 2), silicon, and a silicon alloy, or a combination of one or more of them.

[0156] The rechargeable lithium battery according to one or more embodiments of the present disclosure can be used in motor vehicles, mobile phones and / or any other electronic devices, but the present disclosure is not limited thereto.

[0157] Terms such as “substantially,” “about,” and “approximately” are used as relative terms rather than terms of degree and are intended to encompass inherent biases in measured or calculated values ​​that would be recognized by a person skilled in the art. They may include the stated value and a range of acceptable deviations as determined by a person skilled in the art considering the limitations and errors associated with the measurement of that quantity. For example, “about” may mean within one or more standard deviations, or ±30%, ±20%, ±10%, or ±5% of the stated value.

[0158] The numerical ranges disclosed herein include and are intended to include all subranges containing the same numerical precision. For example, the range “1.0 to 10.0” is intended to include all subranges (such as, for example, 2.4 to 7.6) where the minimum value is equal to or greater than 1.0 and the maximum value is equal to or less than 10.0. Therefore, the applicant reserves the right to amend this specification (including the claims) to expressly describe any subranges included within the ranges expressly described herein.

[0159] One or more exemplary embodiments and comparative examples of this disclosure will be described below. However, the embodiments described below are merely examples, and this disclosure is not limited to the one or more embodiments discussed.

[0160] Example

[0161] Example implementation and comparative examples

[0162] Electrolytes and rechargeable lithium batteries are manufactured using the following method.

[0163] Example Implementation Method 1

[0164] (1) Preparation of electrolyte

[0165] 1.5 mol concentration (M) LiPF6 was dissolved in a non-aqueous organic solvent mixture containing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) mixed in a volume ratio of 20:40:40, and additives were added to prepare the electrolyte.

[0166] As an additive, the compound represented by chemical formula 1A (or chemical formula 1-2-1) is mixed in an amount of 0.5 wt% relative to the total weight of the electrolyte, and the compound represented by chemical formula 2A is mixed in an amount of 0.5 wt% relative to the total weight of the electrolyte.

[0167] Chemical Formula 1A

[0168]

[0169] Chemical formula 2A

[0170]

[0171] (2) Manufacturing of rechargeable lithium batteries

[0172] A slurry of positive electrode active material was prepared by mixing LiFePO4 as the positive electrode active material, polyvinylidene fluoride as the binder, and Ketjen black as the conductive material in a weight ratio of 97:2:1, and dispersing the mixture in N-methylpyrrolidone.

[0173] The positive electrode active material slurry was coated onto an Al foil with a thickness of 14 micrometers (μm), dried at 110°C, and then pressed to manufacture the positive electrode.

[0174] Artificial graphite and silicon-carbon composite, which are used as negative electrode active materials, are mixed in a weight ratio of 93:7. Styrene-butadiene rubber, which is used as a binder, and carboxymethyl cellulose, which is used as a tackifier, are mixed in a weight ratio of 97:1:2. The mixture is then dispersed in distilled water to prepare a negative electrode active material slurry.

[0175] The silicon-carbon composite comprises a core consisting of artificial graphite and silicon particles, and coal pitch coated on the surface of the core.

[0176] The negative electrode active material slurry was coated onto a Cu foil with a thickness of 10 μm, dried at 100 °C, and then pressed to manufacture the negative electrode.

[0177] The positive electrode, negative electrode and 25 μm thick polyethylene separator are assembled to manufacture the electrode assembly, and the electrolyte is introduced to manufacture a rechargeable lithium battery as a prismatic cell type (type) with a thickness of 10 mm.

[0178] That is, in Example Embodiment 1, the electrolyte is prepared by dissolving 1.5M LiPF6 in a non-aqueous organic solvent mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 20:40:40, wherein additives of Chemical Formula 1A and Chemical Formula 2A each account for 0.5 wt% relative to the total weight of the electrolyte. For the rechargeable lithium battery, the positive electrode is made of LiFePO4, polyvinylidene fluoride, and Ketjen black coated on a 14 μm Al foil in a weight ratio of 97:2:1, while the negative electrode is made of a mixture coated on a 10 μm Cu foil obtained by mixing artificial graphite and silicon-carbon composites as negative electrode active materials in a weight ratio of 93:7, styrene-butadiene rubber as a binder, and carboxymethyl cellulose as a tackifier in a weight ratio of 97:1:2. These electrodes are assembled with a 25 μm polyethylene separator, and an electrolyte is introduced to form a 10 mm thick prismatic battery cell.

[0179] Example Implementation Method 2

[0180] The electrolyte and the rechargeable lithium battery are manufactured independently using essentially the same method as in Example Embodiment 1, except that when preparing the electrolyte, 0.5 wt% of a compound represented by Chemical Formula 2B is added instead of the additive represented by Chemical Formula 2A.

[0181] Chemical formula 2B

[0182]

[0183] Example Implementation Method 3

[0184] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example 1, except that LiNi is used. 0.91 Co 0.07 Al 0.02 O2 is used as the active material for the positive electrode.

[0185] Example Implementation Method 4

[0186] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example Embodiment 1, except that LiCoO2 is used as the positive electrode active material.

[0187] Example Implementation Method 5

[0188] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example 1, except that LiNi is used. 0.88 Co 0.08 Mn 0.04 O2 is used as the active material for the positive electrode.

[0189] Comparative Example 1

[0190] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example Implementation 1, except that no additives are added.

[0191] Comparative Example 2

[0192] The electrolyte and the rechargeable lithium battery are manufactured independently using essentially the same method as in Example Embodiment 1, except that when preparing the electrolyte, no compound represented by chemical formula 2A is added as an additive.

[0193] Comparative Example 3

[0194] The electrolyte and the rechargeable lithium battery are manufactured independently using essentially the same method as in Example Embodiment 1, except that when preparing the electrolyte, no compound represented by Chemical Formula 1A is added as an additive.

[0195] Comparative Example 4

[0196] The electrolyte and the rechargeable lithium battery are manufactured independently using essentially the same method as in Example 2, except that when preparing the electrolyte, no compound represented by chemical formula 1A is added as an additive.

[0197] Comparative Example 5

[0198] The electrolyte and the rechargeable lithium battery are manufactured independently using essentially the same method as in Example Embodiment 1, except that when preparing the electrolyte, 0.5 wt% of a compound represented by Chemical Formula 2C is added instead of an additive represented by Chemical Formula 2A.

[0199] Chemical formula 2C

[0200]

[0201] Comparative Example 6

[0202] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example 3, except that no additives are added.

[0203] Comparative Example 7

[0204] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example Implementation 4, except that no additives are added.

[0205] Comparative Example 8

[0206] The electrolyte and rechargeable lithium battery are manufactured independently using essentially the same method as in Example Implementation 5, except that no additives are added.

[0207] Assessment 1: High-Temperature Storage Characteristics (DC-IR Increase Rate and Capacity Retention Rate)

[0208] Each of the rechargeable lithium batteries according to the example embodiments and comparative examples was charged at a constant current and constant voltage of 0.33C and discharged to 2.5V at 0.33 coulombs (C) once to measure the charge / discharge capacity (initial capacity (initial discharge capacity)).

[0209] Each of the rechargeable lithium batteries manufactured according to the example embodiments and comparative examples was charged to 100% state of charge (SOC) (i.e., 100% state of charge when the total charge capacity is set to 100%) under constant current and constant voltage (approximately 4.2V, approximately 0.05C cutoff) conditions, stored at 60°C for 60 days, and then discharged at a constant current of 0.33C until 2.5 volts (V) was reached to measure the discharge capacity (discharge capacity after high-temperature storage).

[0210] The ratio of the discharge capacity after high-temperature storage to the initial discharge capacity is shown in Table 1 as the capacity retention rate.

[0211] For each of the rechargeable lithium batteries according to the example implementation and comparative examples, after measuring the initial DC internal resistance (DC-IR) as ΔV / ΔI (voltage change / current change), the battery is charged to a fully charged state (SOC 100%) at its maximum energy state and stored at a high temperature (60°C) for 60 days in this charged state, and then the DC internal resistance (DC-IR after high temperature storage) is measured.

[0212] The DC-IR increase rate (%) was calculated according to Equation 1 below, and the results are listed in Table 1, where “EE” represents the example implementation, “CE” represents the comparative example, and “mΩ” is milliohms.

[0213] Equation 1

[0214] DC-IR increase rate (%) = (DC-IR after high-temperature storage / initial DC-IR) × 100

[0215] Table 1

[0216]

[0217] Evaluation 2: Cycle life characteristics

[0218] At a high temperature (45°C), each of the rechargeable lithium batteries manufactured according to the example embodiment and comparative example was charged under CC-CV conditions (0.5C, 3.7V for lithium iron phosphate (LFP) or 4.2V for lithium nickel cobalt aluminum oxide (NCA), lithium cobalt oxide (LCO), and lithium nickel cobalt manganese oxide (NCM)) and a 0.05C cutoff condition, and then discharged under CC (1C) and a 2.5V cutoff condition. This cycle was repeated 400 times to measure the change in discharge capacity. The ratio of the discharge capacity after 400 cycles to the discharge capacity after 1 cycle is shown in Table 2 as the capacity retention rate.

[0219] For example, at room temperature (25°C), each of the rechargeable lithium batteries manufactured according to the example embodiment and the comparative example was charged under CC-CV conditions (0.5C, 3.7V (for lithium iron phosphate compounds (LFP) or 4.2V (for lithium nickel cobalt aluminum oxide (NCA), lithium cobalt oxide (LCO), and lithium nickel cobalt manganese oxide (NCM))) and 0.05C cutoff conditions, and then discharged under CC (1C) and 2.5V cutoff conditions, and this cycle was repeated 400 times to measure the change in discharge capacity. The ratio of the discharge capacity after 400 cycles to the discharge capacity after 1 cycle is shown in Table 2 as the capacity retention rate, where “EE” represents the example embodiment and “CE” represents the comparative example.

[0220] Table 2

[0221]

[0222]

[0223] Assessment 3: High-temperature gas generation

[0224] Each of the rechargeable lithium batteries manufactured according to the exemplary embodiment and the comparative example was stored at 60°C for 30 days, and then the amount of gas produced (mL) was measured using refinery gas analysis (RGA). The results are listed in Table 3, where “EE” represents the exemplary embodiment and “CE” represents the comparative example.

[0225] Table 3

[0226]

[0227] Referring to Table 1, it can be observed that, compared to the rechargeable lithium battery according to the comparative example, the rechargeable lithium battery according to the example embodiment has an increased capacity retention rate after high-temperature storage and a reduced DC-IR increase rate. Therefore, it can be determined that the battery's high-temperature characteristics and internal resistance suppression effect are improved.

[0228] Referring to Table 2, it can be observed that, compared to the rechargeable lithium battery according to the comparative example, the rechargeable lithium battery according to the example embodiment exhibits superior or adequate capacity retention at both high and room temperature (e.g., simultaneously). It can be determined that the charge / discharge cycle characteristics are improved due to the inclusion of a first compound and a borate ester lithium salt compound according to one or more embodiments of this disclosure.

[0229] Referring to Table 3, it can be observed that the rechargeable lithium battery according to the exemplary embodiment has less gas generation after high-temperature storage compared to the rechargeable lithium battery according to the comparative example. For example, it can be determined that when the first compound and the borate ester lithium salt compound are used in combination, gas generation is suppressed or reduced to improve the expansion phenomenon.

[0230] Unlike Comparative Example 5 (where the first compound and trimethyl borate (TMB) replacing the borate ester lithium salt compound are used as additives), the rechargeable lithium battery according to the exemplary embodiments of this disclosure may include oxalate functional groups (or borate functional groups) to form a robust film. Therefore, it can be determined that the rechargeable lithium battery according to the exemplary embodiments of this disclosure exhibits improvements in battery charge / discharge cycle characteristics, increased battery internal resistance, and reduced gas generation.

[0231] For example, it can be determined that when the electrolyte according to the exemplary embodiments of this disclosure is used in combination with a positive electrode (one or more of lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium nickel cobalt aluminum oxide (NCA), and lithium nickel cobalt manganese oxide (NCM) as the positive electrode active material), the rechargeable lithium battery exhibits excellent or suitable high-temperature storage characteristics and superior charge / discharge cycle characteristics at both high and room temperatures. Furthermore, when the electrolyte from the exemplary embodiments is used with a positive electrode containing lithium iron phosphate (LFP), lithium cobalt oxide (LCO), lithium nickel cobalt aluminum oxide (NCA), or lithium nickel cobalt manganese oxide (NCM), the resulting rechargeable lithium battery exhibits excellent high-temperature storage characteristics and superior charge / discharge cycle characteristics at both high and room temperatures.

[0232] According to one or more embodiments of this disclosure, rechargeable lithium batteries can be realized that exhibit excellent or adequate cycle life characteristics and improved battery stability by suppressing gas generation and increased battery resistance during high-temperature storage. For example, these rechargeable lithium batteries achieve excellent cycle life characteristics and improved stability by effectively suppressing gas generation and minimizing resistance increase during high-temperature storage.

[0233] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to embodiments of the present disclosure described herein may be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, components of the apparatus may be formed on a single integrated circuit (IC) chip or on separate IC chips. Further, components of the apparatus may be implemented on a flexible printed circuit film, tape-on-a-carrier package (TCP), or printed circuit board (PCB), or formed on a substrate. Further, components of the apparatus may be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components to perform the functions described herein. The computer program instructions are stored in memory, which may be implemented using standard memory devices (such as, for example, random access memory (RAM)) in the computing device. The computer program instructions may also be stored on other non-transitory computer-readable media (such as, for example, CD-ROMs, flash drives, etc.). Furthermore, those skilled in the art should recognize that, without departing from the scope of this disclosure, the functions of a computing device may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed across one or more other computing devices.

[0234] The description of features or aspects within each implementation should generally be considered applicable to other similar features or aspects in other implementations.

[0235] Although this disclosure has been described in conjunction with what is now considered an exemplary embodiment, it should be understood that this 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 should be understood as merely illustrative and not as limiting this disclosure in any way.

Claims

1. An electrolyte, comprising: Non-aqueous organic solvents; Lithium salts; and additive, The additives mentioned above include: The first compound represented by chemical formula 1; and Boronate lithium salt compounds, Chemical Formula 1 In chemical formula 1, R1 may be the same or different, and each is independently hydrogen, halogenated, C1-C10 alkyl, or isocyanate group, wherein at least one R1 is an isocyanate group. R2 may be the same or different, and each is independently hydrogen, halogroup, C1-C10 alkyl or isocyanate group, wherein at least one R2 is an isocyanate group. R3 may be the same or different, and each is independently a hydrogen or cyclohexyl isocyanate residue, and n is an integer from 1 to 10, and The electrolyte mentioned is an electrolyte used in rechargeable lithium batteries.

2. The electrolyte of claim 1, wherein the first compound is represented by chemical formula 1-1. Chemical Formula 1-1 in, In chemical formula 1-1, R1 may be the same or different, and each is independently hydrogen, halogenated, C1-C10 alkyl, or isocyanate group, wherein at least one R1 is an isocyanate group, and R2 may be the same or different, and each is independently hydrogen, halogen, C1 to C10 alkyl or isocyanate group, wherein at least one R2 is an isocyanate group.

3. The electrolyte of claim 1, wherein the first compound is represented by chemical formulas 1-2. Chemical formula 1-2 in, In chemical formulas 1-2, R1 may be the same or different, and each is independently hydrogen, halogroup or C1-C10 alkyl, and R2 may be the same or different, and each may be hydrogen, halogroup or C1 to C10 alkyl group independently.

4. The electrolyte of claim 1, wherein the borate ester lithium salt compound is represented by chemical formula 2. Chemical formula 2 and in, In chemical formula 2, X is a halogroup or a C1-C10 haloalkyl group. m1 is 1 or 2. When m1 is 1, m2 is 2, and When m1 is 2, m2 is 0.

5. The electrolyte of claim 4, wherein the borate ester lithium salt compound comprises at least one selected from lithium bis(oxalate)borate and lithium difluoro(oxalate)borate.

6. The electrolyte of claim 1, wherein the amount of the first compound is 0.01 wt% to 5 wt% relative to the total weight of the electrolyte.

7. The electrolyte of claim 1, wherein the amount of the first compound is 0.1 wt% to 3 wt% relative to the total weight of the electrolyte.

8. The electrolyte of claim 1, wherein the amount of the borate ester lithium salt compound is 0.01 wt% to 5 wt% relative to the total weight of the electrolyte.

9. The electrolyte of claim 1, wherein the amount of the borate ester lithium salt compound is 0.1 wt% to 3 wt% relative to the total weight of the electrolyte.

10. The electrolyte of claim 1, wherein the amount of the additive is 0.1 wt% to 10 wt% relative to the total weight of the electrolyte.

11. The electrolyte of claim 1, wherein the weight ratio of the first compound to the borate ester lithium salt compound is 10:1 to 1:

10.

12. The electrolyte of claim 1, wherein the non-aqueous organic solvent includes carbonate solvents.

13. The electrolyte of claim 12, wherein the carbonate solvent includes ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate.

14. The electrolyte of claim 1, wherein the lithium salt comprises LiPF6.

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

16. A rechargeable lithium battery, comprising: Positive electrode, including positive electrode active material; Negative electrode, including negative electrode active material; and The electrolyte as described in any one of claims 1 to 15.

17. The rechargeable lithium battery of claim 16, wherein the positive electrode active material comprises lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, cobalt-free nickel manganese oxide, or a combination thereof.

18. The rechargeable lithium battery of claim 16, wherein the negative electrode active material comprises carbon-based negative electrode active material, Si-based negative electrode active material, Sn-based negative electrode active material, or a combination thereof.

19. The rechargeable lithium battery of claim 18, wherein the Si-based negative electrode active material comprises: Cores, including Si-type particles; and Coatings, including amorphous carbon.

20. The rechargeable lithium battery of claim 19, wherein the Si particles comprise a subset selected from silicon-carbon composites and SiO2. x At least one of silicon and silicon alloys, wherein x is greater than 0 and less than or equal to 2.

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