Negative electrode and rechargeable lithium battery comprising a negative electrode

Abstract

A negative electrode and a rechargeable lithium battery including the same are provided. The negative electrode includes a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer includes a silicon-carbon composite and a first graphite, the first graphite is artificial graphite, and wherein the silicon-carbon composite includes: secondary particles, primary particles aggregated in the secondary particles; and an amorphous carbon coating layer on the primary particles and the secondary particles, wherein each of the primary particles includes: silicon nanoparticles; and a metal coating layer on the silicon nanoparticles, and wherein the metal coating layer includes a first metal-based material.

Description

[0001] This application claims priority and benefit to Korean Patent Application No. 10-2024-0181839, filed on December 9, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0002] One or more embodiments of this disclosure relate to a negative electrode and a rechargeable lithium battery including the negative electrode. Background Technology

[0003] Recently, with the rapid proliferation of battery-powered electronic devices (such as mobile phones and laptops) and / or electric vehicles, the demand for rechargeable batteries with high energy density and large capacity has been increasing significantly. In response, extensive research and development efforts have been undertaken to enhance the performance of such rechargeable batteries, including rechargeable lithium batteries.

[0004] Rechargeable lithium-ion batteries typically consist of a positive electrode, a negative electrode, and an electrolyte. Each of the positive and negative electrodes contains active materials capable of inserting and deintercalating lithium ions. During charging and discharging, electrical energy is generated through oxidation and reduction reactions as lithium ions move between the electrodes. For example, electrical energy is generated when lithium ions insert into the positive electrode and / or deintercalate from the negative electrode during the discharge process. Summary of the Invention

[0005] One or more aspects of embodiments of this disclosure relate to having a negative electrode with high conductivity not only inside the negative electrode active material but also on the surface of the negative electrode active material.

[0006] One or more aspects of embodiments of this disclosure relate to rechargeable lithium batteries having high energy density, capacity, efficiency and long lifespan.

[0007] Other aspects will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosed embodiments.

[0008] According to one or more embodiments of this disclosure, the negative electrode may include a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer may include a silicon-carbon composite and a first graphite, the first graphite being artificial graphite, and wherein the silicon-carbon composite may include: secondary particles, in which primary particles may aggregate; and an amorphous carbon coating layer on the primary particles and the secondary particles, wherein each of the primary particles may include: silicon nanoparticles; and a metal coating layer on the silicon nanoparticles, wherein the metal coating layer may include a first metallic material.

[0009] According to one or more embodiments of this disclosure, a rechargeable lithium battery may include the aforementioned negative electrode. Attached Figure Description

[0010] The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this disclosure. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. The above and other aspects, features, and advantages of certain embodiments of the disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings.

[0011] Figure 1 This is a schematic concept diagram of a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0012] Figures 2 to 5 Each of these is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 Each shows a pouch-type (or similar) battery.

[0013] Figure 6 This is a cross-sectional view of the negative electrode for a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0014] Figure 7 This is an enlarged view of the negative electrode active material layer according to one or more embodiments of the present disclosure.

[0015] Figure 8 This is a schematic diagram illustrating a silicon-carbon composite according to one or more embodiments of the present disclosure.

[0016] Figure 9 This is a schematic diagram illustrating a silicon-carbon composite according to one or more embodiments of the present disclosure.

[0017] Figure 10 This is an enlarged view of the negative electrode active material layer according to one or more embodiments of the present disclosure.

[0018] Figure 11 This is an enlarged view of the negative electrode active material layer according to one or more embodiments of the present disclosure. Detailed Implementation

[0019] To fully understand the structure and effects of this disclosure, one or more exemplary embodiments will be described with reference to the accompanying drawings. However, this disclosure is not limited to the following exemplary embodiments and may be implemented in one or more suitable forms. The exemplary embodiments are provided merely to illustrate this disclosure and to enable those skilled in the art to fully understand its scope.

[0020] In this disclosure, if (e.g., when) an element is described as "on" another element, it may be directly on said other element, or one or more intervening elements may exist between them. Conversely, if (e.g., when) an element is described as "directly on" another element, there are no intervening elements between them. In the figures, certain thicknesses may be exaggerated to better illustrate technical details. Throughout the disclosure, the same reference numerals indicate the same elements, and for the sake of brevity, their repeated descriptions may be omitted.

[0021] One or more embodiments described herein may be illustrated using sectional views and / or plan views presented as idealized and illustrative examples of this disclosure. For clarity, the thickness of layers and regions in the figures may be exaggerated. The regions shown in the figures are for illustrative purposes and should not be construed as limiting the scope of this disclosure. Although terms such as “first,” “second,” and “third” may be used to describe one or more suitable elements, these terms are used only for distinction and do not imply any particular order or hierarchy. For example, a first element discussed herein may be referred to as a second element without departing from the scope of the disclosure. The embodiments described and illustrated herein may include complementary variations.

[0022] The terminology used in this disclosure is for the purpose of explaining one or more suitable embodiments only and is not intended to limit the disclosure. Unless expressly stated otherwise, the singular form may also include the plural form. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are also intended to include the plural forms. The terms “comprising,” “including,” “having,” and / or variations thereof do not exclude the presence or addition of one or more other components. Furthermore, the terms “comprising,” “including,” “having,” and / or variations thereof, or other similar terms, include or support the terms “consisting of” and “substantially consisting of”, indicating the presence of the stated features, quantities, steps, operations, elements, parts, and / or components, while other features, quantities, steps, operations, elements, parts, components, and / or groups thereof are absent or substantially absent. Additionally, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.”

[0023] In this disclosure, the phrase "the combination of them" can refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0024] Unless otherwise specifically defined, the terms "particle size" or "particle diameter" refer to average particle size / size. Particle size / size can be expressed as median particle size (D50), which corresponds to the diameter / size of 50% by volume of particles in a cumulative particle size distribution. In other words, D50 refers to the average diameter (or size) of particles whose cumulative volume corresponds to 50% by volume in a particle size distribution (e.g., a cumulative distribution), and refers to the value corresponding to 50% of the particle size from the smallest particle when the total number of particles is 100% in a distribution curve accumulated in order from smallest to largest particle size. Average particle size / size (D50) can be measured using a wide range of suitable methods, such as a particle size analyzer, e.g., a HORIBA LA-950 laser particle size analyzer, or by imaging using transmission electron microscopy (TEM) or scanning electron microscopy (SEM). In one or more embodiments, dynamic light scattering can be used, in which particle counts across a size range are analyzed to calculate average particle size / size (D50). In one or more embodiments, laser scattering can be employed, wherein target particles are dispersed in a solvent, introduced into a laser scattering particle measurement device (e.g., an MT 3000 from Microtrac), irradiated with ultrasound at 28 kHz and 60 W, and subsequently analyzed to determine the D50 value based on a 50% cumulative particle size distribution. In this disclosure, "diameter / size" represents the average particle diameter / size when the particles are spherical, and "diameter / size" represents the average major axis length of the particles when the particles are non-spherical.

[0025] In the disclosure, the phrases “A or B”, “A and / or B”, “A / B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B or C” include any one or all possible combinations of the listed elements.

[0026] Figure 1 This is a schematic concept diagram of a rechargeable lithium battery according to one or more embodiments of the present disclosure. (Refer to...) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte solution ELL.

[0027] The positive electrode 10 and the negative electrode 20 can be separated from each other by a diaphragm 30. The diaphragm 30 can be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20 and the diaphragm 30 can be in contact with the electrolyte solution ELL. For example, the positive electrode 10, the negative electrode 20 and the diaphragm 30 can be immersed in the electrolyte solution ELL.

[0028] The electrolyte solution ELL can be a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte solution ELL, lithium ions can move towards the positive electrode 10 or the negative electrode 20 through the membrane 30.

[0029] Positive electrode 10 The positive electrode 10 for a rechargeable lithium battery may include a current collector COL1 and a positive electrode active material layer AML1 on the current collector COL1. The positive electrode active material layer AML1 may include (e.g., in particulate form) a positive electrode active material, and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0030] In one or more embodiments, the positive electrode 10 may further include an additive that can be used as a sacrificial positive electrode.

[0031] Based on 100 wt% of the total weight of the positive electrode active material layer AML1, the amount of positive electrode active material can be from about 90 wt% to about 99 wt%. Based on 100 wt% of the total weight of the positive electrode active material layer AML1, the amounts of binder and conductive material can each be from about 0.5 wt% to about 5 wt%.

[0032] The binder is used to ensure good adhesion between the positive electrode active material particles and also to ensure good adhesion of the positive electrode active material to the current collector COL1. As a non-limiting example, examples of binders may include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0033] Conductive materials (e.g., electrically conductive materials) can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in the battery. Non-limiting examples of conductive materials may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials comprising copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0034] In one or more embodiments, aluminum (Al) can be used as the current collector COL1, but the embodiments disclosed herein are not limited thereto.

[0035] Positive electrode active material The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, in one or more embodiments, at least one of lithium and a composite oxide of a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0036] The composite oxide can be a lithium transition metal composite oxide. Non-limiting examples of composite oxides may include lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and / or combinations thereof.

[0037] In one or more embodiments, one or more compounds represented by any of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (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 (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 (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 (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 (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 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn1-b G b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, and 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0038] In the aforementioned chemical formula, A can be nickel (Ni), cobalt (Co), manganese (Mn), or a combination thereof; X can be Al, Ni, Co, Mn, chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), rare earth elements, or a combination thereof; D can be oxygen (O), fluorine (F), sulfur (S), phosphorus (P), or a combination thereof; G can be Al, Cr, Mn, Fe, Mg, lanthanum (La), cerium (Ce), Sr, V, or a combination thereof; and L 1 It can be Mn, Al, or a combination thereof.

[0039] In one or more embodiments, the positive electrode active material can be, for example, a high-nickel positive electrode active material, based on 100 mol% of the total metals other than lithium in the lithium transition metal complex oxide. The nickel content (e.g., amount) of the high-nickel positive electrode active material is greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be applied to high-capacity, high-density rechargeable lithium batteries.

[0040] negative electrode 20 The negative electrode 20 for a rechargeable lithium battery may include a current collector COL2 and a negative electrode active material layer AML2 on the current collector COL2. The negative electrode active material layer AML2 may include (e.g., in the form of particles) negative electrode active material, and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0041] For example, in one or more embodiments, based on 100 wt% of the total weight of the negative electrode active material layer, the negative electrode active material layer AML2 may include about 90 wt% to about 99 wt% of the negative electrode active material, about 0.1 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0042] The binder can be used to ensure good adhesion between the negative electrode active material particles and also to ensure good adhesion between the negative electrode active material and the current collector COL2. The binder may include non-aqueous (e.g., water-insoluble) binders, aqueous (water-soluble) binders, dry binders, or combinations thereof.

[0043] 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, or combinations thereof.

[0044] Waterborne adhesives may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxygenated alcohol, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0045] When an aqueous binder is used as the binder for the negative electrode, it may further include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may include Na, K, or Li.

[0046] Dry adhesives can be polymeric materials capable of forming fibers. For example, dry adhesives can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0047] Conductive materials (e.g., electrically conductive materials) can be used to impart conductivity (e.g., electrical conductivity) to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in the battery. Non-limiting examples may include: carbon-based materials such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers, such as polyphenylene derivatives; and / or mixtures thereof.

[0048] The 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, or a combination thereof.

[0049] Negative electrode active material The negative electrode active material in the negative electrode active material layer AML2 may include a material that can reversibly intercalate / deintercalate lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, and / or a transition metal oxide.

[0050] The material that can reversibly intercalate / deintercalate lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Crystalline carbon may be graphite, such as natural graphite or artificial graphite in the form of non-fixed shape, sheet, flake, spherical, or fibrous. Amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonization product, calcined coke, etc.

[0051] The lithium metal alloy includes an alloy of lithium and a metal selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), antimony (Sb), lead (Pb), indium (In), zinc (Zn), barium (Ba), radium (Ra), germanium (Ge), aluminum (Al), and tin (Sn).

[0052] The material capable of doping / de-doping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof). The Sn-based negative electrode active material may include Sn, SnO k (0 < k ≤ 2) (for example, SnO2), a Sn-based alloy, or a combination thereof.

[0053] The silicon-carbon composite (for example, in the form of particles) may be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, in one or more embodiments, the silicon-carbon composite may include secondary particles (cores) in which primary silicon particles are aggregated and an amorphous carbon coating layer (shell) on the surface of the secondary particles. Amorphous carbon may also be between the primary silicon particles. For example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in the amorphous carbon matrix.

[0054] In one or more embodiments, 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 an amorphous carbon coating layer on the surface of the core.

[0055] In one or more embodiments, Si-based negative electrode active materials and / or Sn-based negative electrode active materials may be used in combination with carbon-based negative electrode active materials.

[0056] Diaphragm 30 Depending on the type 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 polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer membrane of two or more layers thereof, such as a mixed multilayer membrane such as a polyethylene / polypropylene bilayer membrane, a polyethylene / polypropylene / polypropylene trilayer membrane, or a polypropylene / polypropylene / polypropylene trilayer membrane.

[0057] The diaphragm 30 may include a porous substrate and a coating layer on one or two surfaces (e.g., two opposing surfaces) of the porous substrate, comprising an organic material, an inorganic material, or a combination thereof.

[0058] The porous substrate can be a polymer membrane formed from any one or a copolymer or mixture of two or more of the following: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., TEFLON).

[0059] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0060] 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 combinations thereof, but the embodiments of this disclosure are not limited thereto.

[0061] In one or more embodiments, organic and inorganic materials may be mixed in a coating layer, or a coating layer comprising organic materials and a coating layer comprising inorganic materials may be stacked.

[0062] Electrolyte solution ELL Electrolyte solutions (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0063] Non-aqueous organic solvents can be used as a medium for transporting ions that participate in the electrochemical reactions of rechargeable lithium batteries.

[0064] Non-aqueous organic solvents can be carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof.

[0065] Carbonate solvents can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), etc.

[0066] Ester solvents can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0067] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include: nitriles, such as R-CN (where R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane; etc.

[0068] Non-aqueous organic solvents can be used alone or in combination of two or more.

[0069] Furthermore, if (for example, when) carbonate solvents are 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.

[0070] Lithium salts dissolved in non-aqueous organic solvents supply lithium ions in rechargeable lithium batteries, enabling basic operation of the rechargeable lithium battery and improving lithium ion transport between the positive and negative electrodes. Non-limiting examples of lithium salts include 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+1 SO2)(C y F 2y+The first of the following: (1SO2) (where x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0071] Rechargeable lithium batteries Rechargeable lithium batteries can be classified according to their shape as cylindrical batteries, prismatic batteries, pouch batteries, or coin-shaped batteries, etc. Figures 2 to 5 Each of the above is a schematic diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure. 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. (See reference.) Figures 2 to 5 The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20, and the electrode assembly 40 is housed within the housing 50. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte solution. Figure 2 As shown, in one or more embodiments, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. In one or more embodiments, as Figure 3 As shown, 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. In one or more embodiments, as Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include electrode terminals 70, which may be, for example, positive electrode terminal 71 and negative electrode terminal 72 used as electrical paths for guiding current formed in the electrode assembly 40 to the outside.

[0072] As a non-limiting example, the rechargeable lithium battery according to one or more embodiments can be used in automobiles, mobile phones and / or one or more suitable types (classes) of electrical devices.

[0073] The negative electrode 20 according to one or more embodiments of the present disclosure will be described in more detail below.

[0074] negative electrode 20 Figure 6 This is a cross-sectional view of the negative electrode 20 according to one or more embodiments of the present disclosure. Figure 7 According to one or more embodiments Figure 6 An enlarged view of region M in the image. Figure 8This is a cross-sectional view used to illustrate a silicon-carbon composite (SCC) according to one or more embodiments of the present disclosure. Figure 9 This is a cross-sectional view used to illustrate a silicon-carbon composite (SCC) according to one or more embodiments of the present disclosure. In the following description, references to other materials will not be provided. Figures 1 to 5 The descriptions are of the same items, but the differences will be described in more detail.

[0075] Reference Figure 6 According to one or more embodiments of this disclosure, the negative electrode 20 may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 located on the negative electrode current collector COL2. The negative electrode current collector COL2 is the same as described above.

[0076] Reference Figure 7 The negative electrode active material layer AML2 may include (e.g., in particulate form) a silicon-carbon composite SCC and (e.g., in particulate form) a first graphite GPH1 as the negative electrode active material, and may also include a binder BND and / or a conductive material CDM. Examples of binders BND are as described above.

[0077] Based on a total weight of 100 wt% of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include about 0.1 wt% to about 5 wt% of binder BND. For example, in one or more embodiments, based on a total weight of 100 wt% of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 3 wt%, or about 1 wt% to about 2 wt% of binder BND. The type (variety) of binder BND is as described above. For example, in one or more embodiments, binder BND may include styrene-butadiene rubber and carboxymethyl cellulose.

[0078] Based on a total weight of 100 wt% of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may include approximately 0 wt% to approximately 5 wt% of a conductive material CDM. The type (variety) of the conductive material CDM is as described above. For example, in one or more embodiments, the conductive material CDM may include carbon-based materials. Carbon-based materials may include carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc. Carbon nanotubes may include single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanoparticles (MWCNTs), etc.

[0079] For example, in one or more embodiments, the carbon-based material constituting the conductive material CDM may have a one-dimensional nanostructure. A one-dimensional nanostructure can be defined as a structure, for example, where the dimension in any one of the three dimensions is larger than the dimensions in the other two dimensions. For example, in one or more embodiments, a one-dimensional nanostructure can be defined as a nanostructure whose length is much greater than the diameter or width and thickness of the nanostructure.

[0080] Carbon-based materials with one-dimensional nanostructures can have lengths from about 0.5 micrometers (μm) to about 100 μm. For example, carbon-based materials can have lengths from about 1 μm to about 100 μm, from about 1 μm to about 50 μm, from about 1 μm to about 20 μm, or from about 5 μm to about 20 μm.

[0081] The aspect ratio of carbon-based materials with one-dimensional nanostructures can be from about 10 to about 3000. For example, in one or more embodiments, the aspect ratio of the carbon-based materials can be from about 10 to about 2600, from about 20 to about 2500, or from about 30 to about 2400. The aspect ratio can be calculated as the ratio of the length of the carbon-based material to the diameter of the carbon-based material.

[0082] For example, the size, structure, and length of the carbon-based materials that make up the conductive material CDM can be confirmed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), etc.

[0083] For example, carbon-based materials constituting conductive CDM can be identified using Raman spectroscopy. For instance, in an example of a carbon-based material with a one-dimensional nanostructure, at approximately 70 cm⁻¹... -1 Approximately 300cm -1 Radial breathing mode (RBM) peaks appearing within a certain range can be found in the Raman spectra of conductive CDM materials. For example, in embodiments of carbon-based materials with one-dimensional nanostructures, G - belt and G + The band can appear in the Raman spectrum of the conductive material CDM.

[0084] For example, carbon-based materials that make up conductive CDMs can be identified using X-ray photoelectron spectroscopy (XPS). For instance, complex C 1s peaks can be observed in the XPS spectrum of conductive CDMs.

[0085] The conductive material CDM with the above structure can form line or surface contacts with the components of the negative electrode active material layer AML2. The silicon-carbon composite SCC with a sphericity of approximately 0.85 or greater can have a small interparticle contact area. When the conductive material CDM with the above structure is included, conductive paths between the particles of the silicon-carbon composite SCC and conductive paths between the silicon-carbon composite SCC and / or the first graphite GPH1 can be ensured.

[0086] Based on a total weight of 100 wt% of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may comprise approximately 90 wt% to approximately 99 wt% of the negative electrode active material (i.e., silicon-carbon composite SCC and first graphite GPH1). For example, relative to the total weight of the negative electrode active material layer AML2, the negative electrode active material layer AML2 may comprise approximately 95 wt% to approximately 99 wt% or approximately 97 wt% to approximately 98 wt% of the silicon-carbon composite SCC and first graphite GPH1. When the total amount of silicon-carbon composite SCC and first graphite GPH1 meets the above range, a rechargeable lithium battery with excellent or suitable energy density, capacity, and efficiency, and a long lifespan can be provided.

[0087] The negative electrode active material layer AML2 may contain more first graphite GPH1 than silicon carbide composite SCC. For example, in one or more embodiments, the weight ratio of silicon carbide composite SCC to first graphite GPH1 may be about 2:98 to about 40:60, about 2:98 to about 20:80, about 5:95 to about 15:85, or about 7:93 to about 13:87.

[0088] The amount of silicon-carbon composite (SCC) in the negative electrode active material layer AML2 can be from about 2 wt% to about 40 wt% relative to the total weight of the negative electrode active material layer AML2. For example, in one or more embodiments, the amount of silicon-carbon composite (SCC) in the negative electrode active material layer AML2 can be from about 2 wt% to about 20 wt%, from about 5 wt% to about 15 wt%, or from about 7 wt% to about 13 wt% relative to the total weight of the negative electrode active material layer AML2.

[0089] The amount of the first graphite GPH1 in the negative electrode active material layer AML2 can be the amount remaining after excluding the amounts of silicon carbide composite SCC, binder BND and conductive material CDM from the total weight of the negative electrode active material layer AML2 (e.g., amount).

[0090] When the weight ratio of silicon-carbon composite (SCC) to first graphite GPH1, the amount of SCC, and the amount of first graphite GPH1 meet the above ranges, a rechargeable lithium battery with excellent or suitable energy density, capacity, and efficiency and long life can be provided.

[0091] Reference Figure 8 The silicon-carbon composite (SCC) may include secondary particles (SP) aggregated from primary particles (PP) and an amorphous carbon coating layer (CTL). Each of the primary particles (PP) may include silicon nanoparticles (SNP) and a metal coating layer (MCT) surrounding (e.g., around) the silicon nanoparticles (SNP). The metal coating layer (MCT) may include a first metallic material (MMT1).

[0092] Secondary particles (SPs) can be aggregates of primary particles (PPs). A secondary particle (SP) can be an aggregate of multiple primary particles (PPs). For example, a secondary particle (SP) may include multiple primary particles (PPs) aggregated together. Secondary particles (SPs) can have a spherical or elliptical shape.

[0093] The average particle size of the secondary particles (SP) can be from about 3 μm to about 20 μm. For example, in this disclosure, the average particle size can be measured by a particle size analyzer. The average particle size can refer to the diameter of the particles corresponding to 50% by volume in the cumulative particle size distribution. When the average particle size of the secondary particles (SP) meets the above range, it can exhibit excellent or suitable high-rate characteristics and cycling characteristics.

[0094] The shape of the primary PP particles is not limited. For example, the primary PP particles can be plate-shaped or spherical. For example, in one or more embodiments, the primary PP particles can be flake-shaped (or similar).

[0095] The average particle size of silicon nanoparticles (SNPs) can be from about 10 nanometers (nm) to about 1000 nm. For example, in one or more embodiments, the average particle size of silicon nanoparticles (SNPs) can be from about 10 nm to about 200 nm or from about 20 nm to about 150 nm. When the average particle size of silicon nanoparticles (SNPs) meets the above range, the volume expansion of silicon nanoparticles (SNPs) during charging and discharging can be controlled or selected, and structural collapse can be prevented or reduced.

[0096] For example, in one or more embodiments, the silicon nanoparticle SNP may have a long axis and a short axis. For example, the long axis may be the length (or width) of the silicon nanoparticle SNP, and the short axis may be the thickness of the silicon nanoparticle SNP. For example, the aspect ratio (long axis / short axis) of the silicon nanoparticle SNP may be from about 5 to about 20. When the aspect ratio of the silicon nanoparticle SNP meets the above range, the volume expansion of the silicon nanoparticle SNP during charging and discharging can be controlled or determined, and structural collapse can be prevented or reduced.

[0097] The amount of silicon nanoparticles (SNPs) can be from about 30 wt% to about 80 wt% relative to the total weight of the silicon-carbon composite (SCC). For example, in one or more embodiments, the amount of silicon nanoparticles (SNPs) can be from about 44 wt% to about 75 wt%, from about 50 wt% to about 70 wt%, or from about 50 wt% to about 62 wt% relative to the total weight of the silicon-carbon composite (SCC). When the amount of silicon nanoparticles (SNPs) meets the above ranges, a rechargeable lithium battery with excellent or suitable capacity and efficiency can be provided.

[0098] As will be described in more detail below, the metal-coated layer (MCT) can be formed by mixing a silicon precursor and a metal-based material precursor using a ball mill. The MCT can be disposed on silicon nanoparticles (SNPs). The MCT can surround the silicon nanoparticles (SNPs). In one or more embodiments, the MCT may include a first metal-based material (MMT1) in a layered (layer type) form, the first metal-based material (MMT1) continuously located on the surface of the silicon nanoparticles (SNPs). In one or more embodiments, the MCT may include a first metal-based material (MMT1) existing in an island form on the surface of the silicon nanoparticles (SNPs). Because the surface of the silicon nanoparticles (SNPs) is largely covered by the MCT, the surface of the silicon nanoparticles (SNPs) can be substantially shielded from exposure. This improves the internal conductivity of the silicon-carbon composite (SCC), which in turn improves charge-discharge uniformity. Furthermore, the improved conductivity due to the MCT can increase silicon utilization and reduce side reactions.

[0099] For example, the first metallic material MMT1 can be a metal or a metal compound. The metal compound can be a metal oxide, a metal nitride, or a combination thereof.

[0100] The metal can be a metal capable of alloying with lithium. For example, the metal can be an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition metal, a rare earth element, or a combination thereof. For example, the metal can be silver (Ag), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (Rf), vanadium (V), niobium (Nb), tantalum (Ta), argon (Db), chromium (Cr), molybdenum (Mo), tungsten (W), argonium (Sg), technetium (Tc), rhenium (Re), argonium (Bh), iron (Fe), lead (Pb), and ruthenium. (Ru), osmium (Os), cesium (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), copper (Cu), gold (Au), zinc (Zn), cadmium (Cd), boron (B), aluminum (Al), gallium (Ga), tin (Sn), indium (In), thallium (Tl), germanium (Ge), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), or combinations thereof. For example, in one or more embodiments, the metal may be at least one of Ag, Cu, Al, and Au.

[0101] The thickness of the metal coating layer MCT can be from about 0.1 nm to about 30 nm. For example, in one or more embodiments, the thickness of the metal coating layer MCT can be from about 1 nm to about 30 nm, from about 1 nm to about 20 nm, or from about 5 nm to about 20 nm. When the thickness of the metal coating layer MCT meets the above ranges, the internal conductivity of the silicon-carbon composite SCC can be improved, allowing for substantially uniform utilization of the interior of the silicon-carbon composite SCC during battery operation.

[0102] Amorphous carbon coating layer CTL can be disposed on primary particles PP and secondary particles SP. For example, the amorphous carbon coating layer CTL can surround the primary particles PP and the secondary particles SP. For example, the amorphous carbon coating layer CTL can fill between the primary particles PP and can also be disposed on the surface of the secondary particles SP.

[0103] Amorphous carbon coatings (CTLs) can include amorphous carbon. Amorphous carbon can be non-graphitizable carbon (hard carbon), graphitizable carbon (soft carbon), mesophase pitch carbides, calcined coke, or a combination thereof. Amorphous carbon can possess excellent or suitable hardness and electrical conductivity.

[0104] The thickness of the amorphous carbon coating layer (CTL) can be from about 1 nm to about 2 μm. For example, in one or more embodiments, the thickness of the amorphous carbon coating layer (CTL) can be from about 1 nm to about 500 nm, from about 1 nm to about 300 nm, or from about 20 nm to about 200 nm.

[0105] The amount of amorphous carbon can be the weight remaining after excluding the total weight of silicon nanoparticles (SNP) and the first metallic material (MMT1) from the total weight of the silicon-carbon composite (SCC). For example, in one or more embodiments, the amount of amorphous carbon relative to the total weight of the silicon-carbon composite (SCC) can be about 20 wt% to about 50 wt%, about 25 wt% to about 46 wt%, or about 30 wt% to about 40 wt%.

[0106] When the thickness of the amorphous carbon coating layer CTL and the amount of amorphous carbon meet the above range, the amorphous carbon coating layer CTL can have excellent or suitable hardness, the structure of the silicon-carbon composite SCC can be maintained, and the life of the rechargeable lithium battery can be improved.

[0107] For example, an amorphous carbon coating CTL can exhibit a D band (peak position: 1350±50 cm⁻¹) in the Raman spectrum obtained by Raman spectroscopy. -1 (near) and G band (peak position: 1580±50cm) -1(Nearby). Here, the D / G ratio can refer to the ratio of the maximum peak intensity of the D band to the maximum peak intensity of the G band. For example, in one or more embodiments, the D / G ratio of the amorphous carbon coating layer CTL can be at least about 1.0. For example, in one or more embodiments, the D / G ratio of the amorphous carbon coating layer CTL can be from about 1.0 to about 1.5.

[0108] Reference Figure 9 The amorphous carbon coating layer CTL may also include a second metallic material MMT2. The second metallic material MMT2 may be dispersed within the amorphous carbon coating layer CTL. The inclusion of the second metallic material MMT2 in the amorphous carbon coating layer CTL may be a result of some of the first metallic material MMT1 being incorporated into the amorphous carbon coating layer CTL during the process of forming a metallic coating layer MCT on the surface of silicon nanoparticles SNPs in the fabrication of silicon-carbon composites SCC. For example, the second metallic material MMT2 may be the same as the first metallic material MMT1 described above.

[0109] For example, the second metallic material MMT2 can be a metal or a metal compound. The metal compound can be a metal oxide, a metal nitride, or a combination thereof.

[0110] The metal can be a metal capable of alloying with lithium. For example, the metal can be an alkali metal, alkaline earth metal, Group 13, Group 14, Group 15, Group 16 elements, transition metals, rare earth elements, or combinations thereof. For example, the metal can be Ag, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or combinations thereof. For example, in one or more embodiments, the metal can be at least one of Ag, Cu, Al, and Au.

[0111] The amorphous carbon coating layer CTL, including the second metallic material MMT2, can be distributed on both the surface of the primary particles PP and the surface of the secondary particles SP (e.g., simultaneously distributed on the surface of the primary particles PP and the surface of the secondary particles SP). This means it exists both inside and outside the silicon-carbon composite SCC (e.g., simultaneously inside and outside the silicon-carbon composite SCC), thereby improving the conductivity of the silicon-carbon composite SCC on both the inside and the outside (e.g., simultaneously inside and outside). For example, the amorphous carbon coating layer CTL including the second metallic material MMT2 exists inside and on the surface of the silicon-carbon composite SCC, thereby improving the conductivity of the silicon-carbon composite SCC on both the inside and the surface (e.g., simultaneously inside and on the surface).

[0112] The particle size of the second metal-based material MMT2 can be from 1 nm to 30 nm. For example, in one or more embodiments, the particle size of the second metal-based material MMT2 can be from about 1 nm to about 20 nm or from about 5 nm to about 20 nm. When the particle size of the second metal-based material MMT2 meets the above range, the interior of the silicon-carbon composite SCC can be utilized uniformly (e.g., substantially uniformly) during battery operation.

[0113] In the silicon-carbon composite SCC, the total amount of the first metallic material MMT1 and the second metallic material MMT2 can be from about 0.01 wt% to about 20 wt% relative to (e.g., based on) 100 wt% of the total weight of the silicon-carbon composite SCC. For example, in one or more embodiments, the total amount of the first metallic material MMT1 and the second metallic material MMT2 can be from about 0.05 wt% to about 15 wt% or from about 0.1 wt% to about 10 wt% relative to 100 wt% of the total weight of the silicon-carbon composite SCC. When the total amount of the first metallic material MMT1 and the second metallic material MMT2 meets the above-described range, the internal conductivity of the silicon-carbon composite SCC can be improved, allowing for substantially uniform utilization of the interior of the silicon-carbon composite SCC during battery operation.

[0114] Silicon-carbon composites (SCCs) can have relatively low Brunauer-Emmett-Teller (BET) specific surface areas. For example, in one or more embodiments, the BET specific surface area of ​​the silicon-carbon composite (SCC) can be around 0.5 m². 2 / g to approximately 2m 2 In the range of / g. For example, in one or more embodiments, the BET specific surface area of ​​the silicon-carbon composite SCC can be approximately 0.8m². 2 / g to approximately 2m 2 / g or approximately 0.8m 2 / g to approximately 1.5m2 Within the range of / g. When the BET specific surface area of ​​the silicon-carbon composite (SCC) meets the above range, side reactions with the electrolyte solution can be reduced, and the life of the rechargeable lithium battery can be extended.

[0115] Silicon-carbon composites (SCCs) can have a span value of about 1.1 to about 1.6 according to Equation 1.

[0116] Equation 1 Span value = (D90 - D10) / D50 In the equation, D10 can refer to the particle size corresponding to 10% by volume in the cumulative particle size distribution, D50 can refer to the particle size corresponding to 50% by volume in the cumulative particle size distribution, and D90 can refer to the particle size corresponding to 90% by volume in the cumulative particle size distribution.

[0117] For example, in one or more embodiments, the span value of the silicon-carbon composite SCC can be from about 1.1 to about 1.55 or from about 1.1 to about 1.5. When the span value of the silicon-carbon composite SCC meets the above range, the silicon-carbon composite SCC can substantially exclude fine particles. The silicon-carbon composite SCC can have a low specific surface area, reducing side reactions to the electrolyte solution and extending the life of the rechargeable lithium battery.

[0118] For example, when measured by XRD using CuKα rays, the silicon-carbon composite (SCC) can include peaks corresponding to the Si(111) plane and peaks corresponding to the metal(111) plane. The maximum intensity of the peak corresponding to the Si(111) plane can appear at a diffraction angle (2θ) in the range of about 27.5° to about 29.5°. The maximum intensity of the peak corresponding to the metal(111) plane can appear at a diffraction angle (2θ) in the range of about 37.5° to about 40.0°. For example, the metal can be Ag.

[0119] The intensity (I) of the peak corresponding to the metal (111) surface 金属(111) ) and the intensity of the peak corresponding to the Si(111) surface (I Si(111) The strength ratio of (I) 金属(111) / I Si(111) The strength ratio (I) can be from about 0.05 to about 0.5. For example, the strength ratio (I) can be from about 0.05 to about 0.5. 金属(111) / I Si(111) The strength can be from about 0.2 to about 0.4 or from about 0.1 to about 0.4. For example, the metal can be silver (Ag). When the strength ratio (I... 金属(111) / I Si(111)When the above range is met, silicon and metal (e.g., Ag) can be present in the silicon-carbon composite SCC in desired or suitable amounts, thereby improving the internal conductivity of the silicon-carbon composite SCC and making the interior of the silicon-carbon composite SCC substantially uniformly utilized during battery operation.

[0120] For example, the intensity of a peak can be the height value of the peak or the integral area value of the peak.

[0121] For example, XRD measurements can be performed at a diffraction angle (2θ) of about 20° to about 80°, a scan rate of about 0.044° / s to about 0.089° / s, and a step size of about 0.013° / step to about 0.039° / step.

[0122] Silicon-carbon composites (SCCs) can have spherical or near-spherical shapes. The sphericity (S) of SCCs can be represented by Equation 2.

[0123] Equation 2 Sphericity (S) = P 2 / (4π×A) In Equation 2, A can be the cross-sectional area of ​​the silicon-carbon composite SCC, and P (perimeter) can be the perimeter of the cross-section of the silicon-carbon composite SCC.

[0124] A and P can be derived by obtaining a scanning electron microscope (SEM) image of the cross-section of the negative electrode 20 or a SEM image of the silicon-carbon composite SCC, and by analyzing the cross-section of any silicon-carbon composite SCC identified from the image using a program such as ImageJ. For example, sphericity can be a value obtained when a three-dimensional particle is projected onto a two-dimensional plane.

[0125] A and P can be the cross-sectional area and perimeter if (for example, when) the cross-section of the silicon carbide composite SCC is perfectly spherical, and can also be the cross-sectional area and perimeter obtained along the regions where there are non-uniform regions in the cross-section of the silicon carbide composite SCC.

[0126] According to Equation 2, the sphericity can have values ​​from 0 to 1. The closer the sphericity is to 1 according to Equation 2, the closer the profile of the silicon-carbon composite (SCC) can be to a circle. When the sphericity is closer to zero according to Equation 2, the SCC can be non-spherical (or irregular).

[0127] According to one or more embodiments, the silicon-carbon composite SCC may have a sphericity (S) of about 0.85 to about 1.0 according to Equation 2. For example, in one or more embodiments, the silicon-carbon composite SCC may have a sphericity (S) of about 0.88 to about 0.98 (e.g., about 0.88 to about 0.95, about 0.89 to about 0.92, about 0.93 to about 0.98, or about 0.93 to about 0.95) according to Equation 2. When the sphericity S according to Equation 2 satisfies the above range, the silicon-carbon composite SCC may be spherical or nearly spherical in shape.

[0128] Because the negative electrode active material layer AML2 comprises spherical silicon-carbon composite SCCs, the SCCs can effectively utilize the space within the negative electrode active material layer AML2. The SCCs can have excellent or suitable tap density and can increase the packing density during the production of the negative electrode 20. Furthermore, because the negative electrode active material layer AML2 comprises spherical silicon-carbon composite SCCs, the SCCs can be uniformly (e.g., substantially uniformly) dispersed within the negative electrode active material layer AML2, which helps reduce the expansion rate. When the SCCs are mixed with the first graphite GPH1, the spherical SCCs can be better intercalated into the matrix of the first graphite GPH1, resulting in more uniform (e.g., substantially uniform) dispersion throughout the negative electrode active material layer AML2 and further reducing the expansion rate. Therefore, a rechargeable lithium battery with excellent or suitable energy density, capacity, efficiency, and long lifespan can be provided.

[0129] Silicon-carbon composites (SCCs) can be manufactured using the following methods.

[0130] A method for manufacturing silicon-carbon composites (SCC) according to one or more embodiments of the present disclosure may include: spray drying a dispersion comprising a silicon precursor, a metallic precursor and a solvent to produce secondary particles (S1); and heat-treating the secondary particles and the carbon precursor to form an amorphous carbon coating layer (S3).

[0131] In step (e.g., action or task) S1, a dispersion can be prepared by adding a silicon precursor, a metallic precursor, and a dispersant to a solvent. For example, a mixing process can be performed using a ball mill with zirconia balls, etc. However, the mixing process is not limited to the described example, as long as it can grind the silicon precursor. During the mixing process, micron-sized silicon precursors can be ground into nano-sized primary silicon particles (see...). Figure 8 SNPs in (the context of SNPs).

[0132] For example, in one or more embodiments, the silicon precursor may have an average particle size of about 1 μm to about 10 μm. For example, the average particle size of the nanoscale silicon primary particles may be about 1 nm to about 1000 nm, about 10 nm to about 1000 nm, or about 20 nm to about 150 nm.

[0133] Metallic precursors can be metals, metal nitrides, metal carbides, metal sulfides, metal halides, or combinations thereof. For example, metal halides can be metal fluorides or metal chlorides. The metal can be a metal capable of alloying with lithium. Examples of metals are as described above.

[0134] The silicon precursor and the metallic precursor can be mixed in a weight ratio of about 100:1 to about 100:30. For example, in one or more embodiments, the mixing ratio of the silicon precursor and the metallic precursor can be about 100:1 to about 100:25.

[0135] The dispersant can be stearic acid, boron nitride (BN), magnesium sulfide (MgS), polyvinylpyrrolidone (PVP), or a combination thereof. The dispersant can effectively disperse silicon precursors and metallic precursors in the dispersion.

[0136] Solvents may include alcohols. For example, solvents may include at least one selected from the group consisting of isopropanol, ethanol, and butanol.

[0137] Spray drying can be used to dry primary silicon particles (see...) Figure 8 A metallic coating layer, including metallic materials, is formed on the surface of the SNP (see [reference]). Figure 8 In the MCT), and the primary silicon particles and the metal coating can be densely combined to form secondary particles (see MCT). Figure 8 (SP in the text). Secondary particles can have a substantially uniform particle size, spherical shape, and porous structure.

[0138] In step (e.g., action or task) S3, the secondary particles and carbon precursor may be heat-treated to form a coating. The coating may be... Figure 8 Amorphous carbon coating layer CTL.

[0139] For example, the carbon precursor can be mixed with secondary particles. For example, in one or more embodiments, the carbon precursor may include at least one selected from the group consisting of petroleum coke, coal coke, petroleum pitch, coal pitch, and green coke. For example, the heat treatment may be carried out in a N2 or He atmosphere.

[0140] In one or more embodiments, the carbon precursor may be a gas, and step (e.g., action or task) S3 may be performed by chemical vapor deposition (CVD). For example, the carbon precursor may be disposed on the secondary particles in a gaseous form. For example, the carbon precursor may include methane (CH4) gas, ethylene (C2H4) gas, acetylene (C2H2) gas, propane (C3H8) gas, propylene (C3H6) gas, or combinations thereof.

[0141] In this step (e.g., action or task), a portion of the metallic material may be included in the amorphous carbon coating.

[0142] Heat treatment can be performed at approximately 600°C to approximately 1,000°C. Dispersants can be removed during heat treatment. When the heat treatment temperature meets the above range, excessive growth of silicon nanoparticles can be prevented or reduced, SiC formation can be prevented or reduced, and the electrical conductivity of amorphous carbon can be improved.

[0143] Subsequently, the method for manufacturing silicon-carbon composites (SCCs) according to one or more embodiments of this disclosure may further include a grading step (e.g., an action or task) (S5). The grading step (e.g., an action or task) S5 may be performed using a sieve, such that the span values ​​of the silicon-carbon composites (SCCs) satisfy the range described above.

[0144] In one or more embodiments, a method for manufacturing silicon-carbon composites (SCC) according to the present disclosure may include: spray drying a dispersion including a silicon precursor to produce secondary particles; forming a metal coating on the secondary particles using chemical vapor deposition (CVD); and heat-treating a carbon precursor to form an amorphous carbon coating on the secondary particles having the metal coating.

[0145] Return to reference Figure 7 The negative electrode active material layer AML2 may also include (e.g., in particulate form) a first graphite GPH1. The first graphite GPH1 may be crystalline carbon. Crystalline carbon may be more malleable than amorphous carbon.

[0146] The first graphite, GPH1, can be synthetic graphite. Synthetic graphite can possess excellent or suitable electrical conductivity. Synthetic graphite can have a highly oriented and substantially uniform structure. Synthetic graphite can have more lithium-ion migration pathways than natural graphite. Synthetic graphite can exhibit high charge / discharge efficiency, excellent or suitable fast-charging characteristics, and long lifespan.

[0147] For example, in one or more embodiments, the first graphite GPH1 may also include amorphous carbon surrounding (e.g., around) the artificial graphite. For example, the amorphous carbon may be soft carbon.

[0148] The first graphite GPH1 may not be spherical. For example, in one or more embodiments, the first graphite GPH1 may be irregular or non-uniform. The sphericity of the first graphite GPH1 according to Equation 2 may be less than the sphericity of the silicon-carbon composite SCC according to Equation 2. For example, in one or more embodiments, the sphericity GPH1 of the first graphite according to Equation 2 may be about 0.5 to about 0.95, about 0.6 to about 0.9, or about 0.65 to about 0.85, or about 0.65 or greater and less than about 0.85.

[0149] The aspect ratio of the first graphite GPH1 can be from about 1 to about 3. The aspect ratio of the first graphite GPH1 can be defined as the ratio of the length of the major axis to the length of the minor axis of the first graphite GPH1.

[0150] For example, the first graphite GPH1 can be identified by X-ray diffraction (XRD) analysis, graphitization degree analysis, Raman analysis, etc.

[0151] For example, the graphitization degree of the first graphite GPH1 can be less than about 90%. In this disclosure, "graphitization degree" can refer to the ratio of layered structures contained in graphite. High graphitization degree can refer to graphite containing a large number of layered structures. Graphitization degree can be obtained by X-ray diffraction measurement. For example, using an X-ray diffractometer (e.g., Bruker D8 Discover), the d002 value can be measured according to JIS K 0131-1996 or JB / T 4220-2011 standards, and then the graphitization degree can be determined by calculating (0.344-d002) / (0.344-0.3354)×100%. Here, d002 is the interlayer spacing of the graphite crystal structure expressed in nanometers (nm). X-ray diffraction measurements can be performed using CuKα rays as the target ray, for example, at a wavelength of λ ± 0.02 Å, a diffraction angle (2θ) of about 20° to about 80°, and a scan rate of about 1° / min to about 5° / min.

[0152] A negative electrode 20 including a negative electrode active material layer AML2 and a rechargeable lithium battery according to one or more embodiments of the present disclosure can have the following characteristics by including the above-described structure.

[0153] The negative electrode active material layer AML2 according to one or more embodiments of the present disclosure includes a silicon-carbon composite SCC that can be uniformly (e.g., substantially uniformly) utilized from its outer region to its inner region during charge and discharge, and a first graphite GPH1 that can improve the conductivity of the outer surface of the silicon-carbon composite SCC, thereby improving the conductivity of the negative electrode 20 and reducing resistance. Therefore, the rechargeable lithium battery according to one or more embodiments of the present disclosure can have excellent or suitable energy density, capacity, and efficiency, and can also have a long lifespan due to reduced load on the electrode plates.

[0154] Figure 10 and Figure 11 Each of the figures is used to illustrate other embodiments of this disclosure. In the embodiments described later, the figures referenced above will not be described in greater detail. Figures 1 to 8 The technical features described are repeated, and the differences will be described in more detail.

[0155] Reference Figure 10 In addition to the silicon-carbon composite SCC, the first graphite GPH1, the binder BND, and the conductive material CDM, the negative electrode 20 according to one or more embodiments of this disclosure may also include a second graphite GPH2. The second graphite GPH2 may be crystalline carbon. Crystalline carbon can be more malleable than amorphous carbon.

[0156] The second graphite, GPH2, can be natural graphite. Natural graphite can possess excellent or suitable electrical conductivity. Natural graphite can have a large charge / discharge capacity. Natural graphite can have low mechanical strength and can be easily pressed during the pressing of the negative electrode active material layer AML2. Therefore, the density of the negative electrode active material layer AML2 can be increased.

[0157] For example, in one or more embodiments, the second graphite GPH2 may also include amorphous carbon surrounding (e.g., around) natural graphite. For example, the amorphous carbon may be soft carbon.

[0158] The second graphite GPH2 may not be spherical. For example, the second graphite GPH2 may be irregular or non-uniform. The sphericity GPH2 of the second graphite according to Equation 2 may be less than the sphericity of the silicon-carbon composite SCC according to Equation 2. For example, in one or more embodiments, the sphericity GPH2 of the second graphite according to Equation 2 may be about 0.5 to about 0.95, about 0.6 to about 0.9, about 0.65 to about 0.85, or about 0.65 or greater and less than about 0.85.

[0159] The aspect ratio of the second graphite GPH2 can be from about 1 to about 3.

[0160] For example, the second graphite GPH2 can be identified by X-ray diffraction (XRD) analysis, graphitization degree analysis, Raman analysis, etc.

[0161] For example, as a result of X-ray diffraction (XRD) analysis of the second graphite GPH2, broad diffraction peaks can be observed. For example, peaks corresponding to the (002) plane can be widely distributed.

[0162] For example, the crystallite size values ​​along the a-axis (La) and c-axis (Lc) from X-ray diffraction analysis of second graphite GPH2 can be small.

[0163] For example, the degree of graphitization of the second graphite GPH2 may be at least about 90%. For example, in one or more embodiments, the degree of graphitization of the second graphite GPH2 may be from about 98% to about 100%.

[0164] When further comprising a second graphite GPH2, the negative electrode active material layer AML2 may comprise approximately 90 wt% to approximately 99 wt% of the silicon-carbon composite SCC, the first graphite GPH1, and the second graphite as negative electrode active materials relative to the total weight of the negative electrode active material layer AML2. For example, in one or more embodiments, the negative electrode active material layer AML2 may comprise an amount of approximately 95 wt% to approximately 99 wt% or approximately 97 wt% to approximately 98 wt% of the silicon-carbon composite SCC, the first graphite GPH1, and the second graphite GPH2 relative to the total weight of the negative electrode active material layer AML2.

[0165] The weight ratio of silicon-carbon composite SCC to graphite (first graphite GPH1 and second graphite GPH2) can be from about 2:98 to about 40:60. For example, in one or more embodiments, the weight ratio of silicon-carbon composite SCC to graphite (first graphite GPH1 and second graphite GPH2) can be from about 2:98 to about 20:80, from about 5:95 to about 15:85, or from about 7:93 to about 13:87.

[0166] The weight ratio of the first graphite GPH1 to the second graphite GPH2 can be from about 8:2 to about 5:5.

[0167] When the amounts of silicon-carbon composite (SCC), first graphite GPH1, and second graphite GPH2 meet the above ranges, the energy density and charge / discharge capacity of rechargeable lithium batteries can be further increased.

[0168] Reference Figure 11 In addition to the silicon-carbon composite SCC, the first graphite GPH1, the binder BND, and the conductive material CDM, the negative electrode 20 according to one or more embodiments of this disclosure may also include a third graphite GPH3. The third graphite GPH3 may be crystalline carbon. Crystalline carbon can be more malleable than amorphous carbon.

[0169] The third type of graphite, GPH3, can be synthetic graphite. Synthetic graphite can possess excellent or suitable electrical conductivity. Synthetic graphite can have a highly oriented and substantially uniform structure. Synthetic graphite can have more lithium-ion migration pathways than natural graphite. Synthetic graphite can exhibit high charge / discharge efficiency, excellent or suitable fast-charging characteristics, and long lifespan.

[0170] For example, in one or more embodiments, the third graphite GPH3 may also include amorphous carbon surrounding (e.g., around) the artificial graphite. For example, the amorphous carbon may be soft carbon.

[0171] The third graphite GPH3 may not be spherical. For example, the third graphite GPH3 may be irregular or non-uniform. The sphericity of the third graphite GPH3 according to Equation 2 may be less than the sphericity of the silicon-carbon composite SCC according to Equation 2. For example, in one or more embodiments, the sphericity of the third graphite GPH3 according to Equation 2 may be about 0.1 or greater and less than about 0.5.

[0172] The aspect ratio of the third graphite GPH3 can be greater than about 3 and less than or equal to about 20.

[0173] When further comprising a third graphite GPH3, the negative electrode active material layer AML2 may comprise about 90 wt% to about 99 wt% of the silicon-carbon composite SCC, the first graphite GPH1, and the third graphite GPH3, based on 100 wt% of the total weight of the negative electrode active material layer AML2. For example, in one or more embodiments, the negative electrode active material layer AML2 may comprise the silicon-carbon composite SCC, the first graphite GPH1, and the third graphite GPH3 in an amount of about 95 wt% to about 99 wt% or about 97 wt% to about 98 wt% relative to (e.g., based on) 100 wt% of the total weight of the negative electrode active material layer AML2.

[0174] The weight ratio of silicon-carbon composite SCC to graphite (first graphite GPH1 and third graphite GPH3) can be from about 2:98 to about 40:60. For example, in one or more embodiments, the weight ratio of silicon-carbon composite SCC to graphite (first graphite GPH1 and third graphite GPH3) can be from about 2:98 to about 20:80, from about 5:95 to about 15:85, or from about 7:93 to about 13:87.

[0175] The weight ratio of the first graphite GPH1 to the third graphite GPH3 can be from about 8:2 to about 5:5.

[0176] When the amounts of silicon-carbon composite (SCC), first graphite GPH1, and third graphite GPH3 meet the above ranges, the energy density, capacity, and charge / discharge efficiency of rechargeable lithium batteries can be further increased, and their lifespan can be further extended.

[0177] The present disclosure will be described in more detail below with reference to examples. However, these examples are intended to illustrate the present disclosure, and the scope of the invention is not limited to these examples.

[0178] Preparation Example: Fabrication of Silicon-Carbon Composite (SCC) A silicon precursor with an average particle size of 8 μm, nano-sized Ag (with an average particle size of 100 nm), and stearic acid dispersant were added to ethanol, and the mixture was ground and mixed for 8 hours using a ball mill with zirconia balls to prepare a dispersion. The weight ratio of silicon precursor to dispersant was 100:25, and the weight ratio of silicon precursor to nano-sized Ag was 100:20. Thus, primary silicon particles with an average particle size of 100 nm were formed, and a metal coating layer (Ag coating layer) was formed on the surface of the primary silicon particles.

[0179] Secondary particles with an average particle size of 7 μm were prepared by spray drying the dispersion. In the secondary particles, multiple primary silicon particles aggregated and formed a porous structure.

[0180] Secondary particles and petroleum asphalt are mixed at a weight ratio of 60:40 and heat-treated at 1000°C in an N2 atmosphere to form an amorphous carbon coating layer (e.g., in / on the secondary particles).

[0181] Subsequently, a grading step (e.g., an action or task) is performed to ensure that the span values ​​meet the range described above, thereby manufacturing the silicon-carbon composite (SCC).

[0182] The fabricated silicon-carbon composite (SCC) comprises secondary particles in which primary particles are aggregated, and an amorphous carbon coating layer on both the primary and secondary particles. Each primary particle comprises silicon nanoparticles with an average particle size of 100 nm and a metal coating layer (Ag coating layer, thickness = 20 nm) on the silicon nanoparticles. The secondary particles have an average particle size of 7 μm. The amorphous carbon coating layer contains Ag particles with a particle size of 15 nm.

[0183] Here, relative to the total weight of the silicon-carbon composite SCC, the total amount of Ag is 10 wt%, the amount of silicon nanoparticles is 50 wt%, and the amount of amorphous carbon is 40 wt%. The sphericity of the silicon-carbon composite SCC is 0.94.

[0184] Example 1 A slurry was prepared by mixing 97.5 wt% of the negative electrode active material (a silicon-carbon composite SCC:first graphite GPH1 in a weight ratio of 13:87 according to the preparation example), 1 wt% of the conductive material (carbon nanotubes), and 1.5 wt% of the binder (carboxymethyl cellulose and styrene-butadiene rubber) with distilled water. For the first graphite GPH1, artificial graphite with a sphericity of 0.8 and an aspect ratio of 2 was used. The slurry was coated onto a Cu foil, dried, and pressed to prepare the negative electrode. The negative electrode active material layer of the prepared negative electrode comprised a silicon-carbon composite SCC and a first graphite GPH1 in a weight ratio of 13:87.

[0185] Next, to fabricate the silicon-carbon composite (SCC), a silicon precursor with an average particle size of 8 μm, nano-sized Ag particles (average particle size of 100 nm), and a stearic acid dispersant were added to ethanol. The mixture was milled and mixed for 8 hours using a ball mill with zirconia balls to obtain primary silicon particles with an average particle size of 100 nm and a metallic coating layer (Ag coating) on ​​their surface. The dispersion was then spray-dried to form secondary particles with an average particle size of 7 μm, creating a porous structure. These secondary particles were mixed with petroleum asphalt at a weight ratio of 60:40 and heat-treated at 1000 °C under a N2 atmosphere to form an amorphous carbon coating layer. The final silicon-carbon composite (SCC) comprises secondary particles with aggregated primary particles, each secondary particle having silicon nanoparticles with an Ag coating layer, and an amorphous carbon coating layer containing the Ag particles.

[0186] In Example 1, a slurry was prepared by mixing 97.5 wt% of the negative electrode active material (a silicon-carbon composite SCC and graphite GPH1 in a weight ratio of 13:87), 1 wt% of the conductive material (carbon nanotubes), and 1.5 wt% of the binder (carboxymethyl cellulose and styrene-butadiene rubber) with distilled water. The slurry was coated onto a Cu foil, dried, and pressed to prepare the negative electrode.

[0187] As provided in more detail below, subsequent examples show variations in the weight ratio of silicon-carbon composite SCC and graphite GPH1 or the inclusion of different types of graphite (GPH2 and GPH3) to prepare negative electrodes with different compositions, demonstrating the versatility of silicon-carbon composite SCC in enhancing the performance of rechargeable lithium batteries.

[0188] Example 2 Except that the silicon-carbon composite SCC and the first graphite GPH1 are mixed in a weight ratio of 8:92 as the negative electrode active material in the preparation of the slurry, the negative electrode is prepared in essentially the same manner as in Example 1. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and the first graphite GPH1 in a weight ratio of 8:92.

[0189] Example 3 Except that the silicon-carbon composite SCC and the first graphite GPH1 are mixed in a weight ratio of 3:97 as the negative electrode active material in the preparation of the slurry, the negative electrode is prepared in essentially the same manner as in Example 1. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and the first graphite GPH1 in a weight ratio of 3:97.

[0190] Example 4 Except that the silicon-carbon composite SCC and the first graphite GPH1 are mixed in a weight ratio of 20:80 as the negative electrode active material in the preparation of the slurry, the negative electrode is prepared in essentially the same manner as in Example 1. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and the first graphite GPH1 in a weight ratio of 20:80.

[0191] Example 5 The negative electrode was prepared in essentially the same manner as in Example 1, except that: in the preparation of the slurry, silicon-carbon composite SCC and graphite (first graphite GPH1: second graphite GPH2 = 5:5 by weight) were mixed in a weight ratio of 13:87 as the negative electrode active material, and natural graphite with a sphericity of 0.8 and an aspect ratio of 2 was used as the second graphite GPH2. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and graphite (first graphite GPH1 and second graphite GPH2) in a weight ratio of 13:87, and the weight ratio of first graphite GPH1 to second graphite GPH2 is 5:5.

[0192] Example 6 The negative electrode was prepared in essentially the same manner as in Example 1, except that in the preparation of the slurry, silicon-carbon composite SCC and graphite (first graphite GPH1: third graphite GPH3 = 5:5 by weight) were mixed in a weight ratio of 13:87 as the negative electrode active material, and artificial graphite with a sphericity of 0.3 and an aspect ratio of 8 was used as the third graphite GPH3. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and graphite (first graphite GPH1 and third graphite GPH3) in a weight ratio of 13:87, and the weight ratio of first graphite GPH1 to third graphite GPH3 is 5:5.

[0193] Comparison Example 1 The negative electrode was prepared in essentially the same manner as in Example 1, except that only the silicon-carbon composite SCC of the preparation example was added as the negative electrode active material during the preparation of the slurry. The negative electrode active material layer of the prepared negative electrode comprises silicon-carbon composite SCC and first graphite GPH1 in a weight ratio of 100:0.

[0194] Comparison Example 2 The negative electrode was prepared in essentially the same manner as in Example 1, except that a silicon-carbon composite made by mixing without adding any nano-sized Ag was used instead of the silicon-carbon composite (SCC) in the preparation example.

[0195] Preparation of rechargeable lithium batteries Half-cells were fabricated using the aforementioned negative electrode, lithium metal counter electrode, and electrolyte. The electrolyte used was an organic solvent mixture in which ethylene carbonate (EC) and dimethyl carbonate (DMC) were dissolved in a 3:7 volume ratio of 1M LiPF6.

[0196] Furthermore, using conventional methods in the art, coin-type (or similar) full cells were fabricated using the aforementioned negative electrode, LiCoO2 positive electrode, and electrolyte. The electrolyte used was an organic solvent mixture in which ethylene carbonate (EC) and dimethyl carbonate (DMC) dissolved in a 3:7 volume ratio of 1M LiPF6.

[0197] Evaluation Example 1: Performance Evaluation of the Negative Electrode The resistivity of the negative electrode according to Examples 1 to 6, as well as Comparative Examples 1 and 2, is evaluated.

[0198] The resistance of the negative electrode according to the example and comparative examples was measured using a powder resistivity measurement system (MCP-PD51, Mitsubishi Chemical Group). The slurries used in the example and comparative examples were dried and then ground into powder. A certain amount of each powder was filled into a holder, and pressure was applied to prepare the corresponding granules. The mass of each granule was 1.5 g, and the radius of each granule was 10 mm. The resistance (R) of each granule was measured using the four-point probe method under each applied pressure. Taking into account the thickness and shape of the granules, the resistivity at a compressed density of 1.6 g / cc was calculated using a correction factor, and the obtained resistance value was obtained. Conductivity is inversely proportional to resistivity.

[0199] Resistivity calculation equation: ρ = G × R, G = 3.575 × t (ρ: resistivity, R: resistance value, G: shape correction factor, t: particle thickness) The results are shown in Table 1.

[0200] Table 1

[0201] Referring to Table 1, the negative electrodes of Examples 1 to 6 all include silicon carbide composite (SCC) and graphite together, such that their resistivity is less than that of the negative electrode of Comparative Example 1. Observing the results of the negative electrodes of Examples 1 to 4, it is confirmed that when the negative electrode includes silicon carbide composite (SCC) and graphite together, the resistivity decreases with increasing amount of graphite.

[0202] Furthermore, the negative electrodes according to Examples 1, 5, and 6 each comprise a silicon-carbon composite (SCC) containing a metal coating layer and a second metal-like material, and therefore each has a lower resistivity than the negative electrode according to Comparative Example 2.

[0203] Therefore, it was confirmed that each of the negative electrodes according to Examples 1 to 6 has excellent or suitable conductivity.

[0204] Evaluation Example 2: Performance Evaluation of Rechargeable Lithium-ion Batteries The capacity, efficiency, and lifespan of rechargeable lithium batteries comprising the corresponding negative electrodes according to Examples 1 to 6, as well as Comparative Examples 1 and 2, were evaluated.

[0205] The charge-discharge capacity was evaluated by charging and discharging a half-cell, including the negative electrode according to the various examples and comparative examples, once at 0.1C. The charge-discharge efficiency (i.e., efficiency) was obtained by calculating the ratio of the measured discharge capacity to the measured charge capacity.

[0206] The coin-type (or similar) full cells manufactured in the example and comparative examples were each charged and discharged once at 0.1C within the range of 2.5V to 4.2V, and then charged and discharged once at 0.2C, and then repeated for n cycles at 1C. The charge / discharge method and cutoff conditions are as follows.

[0207] Charging: Constant current-constant voltage, 4.2V / 0.01C cutoff Discharge: Constant voltage, cutoff at 2.5V The number of cycles (n) at which the ratio of the discharge capacity of the nth cycle to the discharge capacity of the 1st cycle (capacity retention rate) reaches 85% is used to represent the battery life.

[0208] The results are shown in Table 2.

[0209] Table 2

[0210] Referring to Table 2, the rechargeable lithium batteries including Examples 1 to 6 each incorporate silicon-carbon composite (SCC) and graphite together, thus exhibiting superior charge-discharge efficiency and longer lifespan compared to the rechargeable lithium battery including Comparative Example 1, while possessing a discharge capacity of 380 mAh / g or greater. Observing the results of the rechargeable lithium batteries including Examples 1 to 4, it can be confirmed that although the discharge capacity decreases with increasing graphite content when SCC and graphite are included together, the charge-discharge efficiency and lifespan characteristics are improved. Specifically, it is confirmed that the rechargeable lithium batteries including Examples 1 and 2 each exhibit a discharge capacity of 450 mAh / g or higher, a charge-discharge efficiency of 90% or higher, and a cycle life of 500 or more cycles with a capacity retention of 85%, indicating that they demonstrate excellent or suitable results in all aspects of discharge capacity, charge-discharge efficiency, and lifespan characteristics.

[0211] Furthermore, it has been confirmed that, compared with the rechargeable lithium battery including Comparative Example 2, the rechargeable lithium batteries including Examples 1, 5, and 6, each comprising a silicon-carbon composite material (SCC) having a metal coating and a second metal-like material, are superior or suitable in all aspects of discharge capacity, charge-discharge efficiency, and lifespan characteristics.

[0212] The negative electrode according to one or more examples of this disclosure can have low resistance and excellent or suitable conductivity, making it possible to reduce the load on the electrode plate. Since lower resistance facilitates smoother electron flow during charge-discharge cycles, this reduction in load can lead to improved battery efficiency and performance. The combination of silicon-carbon composite (SCC) with a metal coating and graphite enhances the conductivity of the negative electrode, thereby minimizing or reducing energy loss and enhancing the overall battery function. This characteristic is advantageous in applications requiring high power output and rapid charge-discharge cycles, such as in electric vehicles and / or portable electronic devices.

[0213] The rechargeable lithium-ion batteries according to one or more examples of this disclosure can have excellent or suitable energy densities and can be excellent or suitable in all aspects of discharge capacity, efficiency, and lifespan characteristics. The silicon-carbon composite (SCC) with its unique structure and composition contributes to higher energy storage capacity and extended battery life. Evaluation results show that batteries incorporating the SCC and graphite combination exhibit superior charge-discharge efficiency and longer lifespan compared to conventional batteries. For example, batteries from Examples 1 and 2 demonstrate discharge capacities exceeding 450 mAh / g, charge-discharge efficiencies exceeding 90%, and lifespans exceeding 500 cycles. These properties make the disclosed rechargeable lithium-ion batteries suitable for demanding applications, ensuring reliable performance and extended operating cycles, which is desirable for consumer electronics, renewable energy storage systems, and / or electric vehicles.

[0214] In this disclosure, expressions such as “at least one of…”, “one of…”, and “selected from” modify the entire list of elements without modifying any individual elements within that list when following a list of elements. For example, “at least one of a, b, or c”, “at least one selected from a, b, and c”, “at least one selected from a to c”, etc., can indicate only a, only b, only c, both a and b (e.g., both a and b at the same time), both a and c (e.g., both a and c at the same time), both b and c (e.g., both b and c at the same time), all of a, b, and c, or variations thereof. The “ / ” used herein may be interpreted as “and” or “or” depending on the context.

[0215] In the context of this disclosure and unless otherwise defined, the term “use” and its variations may be considered synonymous with the term “utilize” and its variations, respectively.

[0216] In this disclosure, the term "group" as used herein refers to a group in the periodic table of elements according to the group system of groups 1 to 18 of the International Union of Pure and Applied Chemistry ("IUPAC").

[0217] As used herein, the terms “substantially,” “about,” and similar terms are used as approximate terms rather than terms of degree and are intended to account for the inherent biases of measured or calculated values ​​that would be recognized by one of ordinary skill in the art. As used herein, “about” or “approximately” also includes the stated value and means: within an acceptable range of deviation for a particular value, taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., limitations of the measurement system), as determined by one of ordinary skill in the art. For example, “about” may mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0218] Any numerical range described herein is intended to include all subranges with the same numerical precision contained within the described range. For example, the range "1.0 to 10.0" is intended to include all subranges between the described minimum value of 1.0 and the described maximum value of 10.0 (and includes both the described minimum value of 1.0 and the described maximum value of 10.0), i.e., having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as 2.4 to 7.6. Any maximum numerical limit described herein is intended to include all lower numerical limits contained therein, and any minimum numerical limit described in this specification is intended to include all higher numerical limits contained therein. Therefore, the applicant reserves the right to amend this specification and the claims to expressly describe any subranges contained within the range expressly described herein.

[0219] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to embodiments of the invention described herein can be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuits), software, or a combination of software, firmware, and hardware. For example, various components of the apparatus can be formed on a single integrated circuit (IC) chip or on a discrete IC chip. Furthermore, various components of the apparatus can be implemented on a flexible printed circuit film, tape-on-a-carrier package (TCP), printed circuit board (PCB), or formed on a substrate. Additionally, various components of the apparatus can 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 various functions described herein. The computer program instructions are stored in memory that can be implemented in the computing device using standard memory devices, such as random access memory (RAM). The computer program instructions can also be stored in other non-transitory computer-readable media, such as CD-ROMs, flash drives, etc. Furthermore, those skilled in the art will recognize that, without departing from the scope of this disclosure, the functions of various computing devices can be combined or integrated into a single computing device, or the functions of a particular computing device can be distributed across one or more other computing devices.

[0220] Those skilled in the art will understand that, in view of the disclosure as a whole, each suitable feature of the various embodiments of the disclosure may be combined in part or in whole, or combined with one another, and may be technically interlocked and operated in a variety of suitable ways, and unless otherwise stated or implied, each embodiment may be implemented independently or in combination with one another in any suitable manner.

[0221] While this disclosure has been described with reference to exemplary embodiments, it should be understood that these embodiments are provided for illustrative purposes only and do not limit the scope of this disclosure. Various modifications and equivalent arrangements may be made without departing from the spirit and scope of the appended claims and their equivalents. Therefore, the described embodiments should be considered as examples and not as limitations on this disclosure.

Claims

1. A negative electrode, the negative electrode comprising: Negative electrode current collector; as well as Negative electrode active material layer, The negative electrode active material layer comprises: a silicon-carbon composite; and a first graphite, wherein the first graphite is artificial graphite, and The silicon-carbon composite comprises: secondary particles, including a plurality of primary particles; and an amorphous carbon coating layer on the plurality of primary particles and the secondary particles. Each of the plurality of primary particles comprises: a silicon nanoparticle; and a metal coating layer on the silicon nanoparticle, and The metal coating layer includes a first metallic material.

2. The negative electrode according to claim 1, wherein, The first metallic material is a metal or a metal compound. The metal compound is a metal oxide, a metal nitride, or a combination thereof, and The metal is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a group 15 element, a group 16 element, a transition metal, a rare earth element, or a combination thereof.

3. The negative electrode according to claim 2, wherein, The metal is Ag, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or combinations thereof.

4. The negative electrode according to claim 2, wherein, In the XRD spectrum obtained using CuKα rays, the peak corresponding to the (111) plane of the metal has the maximum intensity at a diffraction angle (2θ) in the range of 37.5° to 40.0°.

5. The negative electrode according to claim 2, wherein, In the XRD spectrum obtained using CuKα rays, the intensity ratio I of the peak corresponding to the (111) plane of the metal and the peak corresponding to the (111) plane of Si is... 金属(111) / I Si(111) It ranges from 0.05 to 0.

5.

6. The negative electrode according to claim 1, wherein, The amorphous carbon coating layer includes a second metallic material.

7. The negative electrode according to claim 6, wherein, The second metallic material has a particle size of 1 nm to 30 nm.

8. The negative electrode according to claim 6, wherein, Based on 100 wt% of the total weight of the silicon-carbon composite, the total amount of the first metallic material and the second metallic material is from 0.01 wt% to 20 wt%.

9. The negative electrode according to claim 1, wherein, The amorphous carbon coating has a D / G ratio of 1.0 to 1.

5.

10. The negative electrode according to claim 1, wherein, The sphericity of the silicon-carbon composite is from 0.85 to 1.

0.

11. The negative electrode according to claim 1, wherein, The silicon-carbon composite has a density of 0.5 m. 2 / g to 2m 2 / g BET specific surface area.

12. The negative electrode according to claim 1, wherein, The sphericity of the first graphite is 0.5 to 0.

95.

13. The negative electrode according to claim 1, wherein, The aspect ratio of the first graphite is 1 to 3.

14. The negative electrode according to claim 1, wherein, Based on 100wt% of the total weight of the negative electrode active material layer, the amount of the silicon-carbon composite and the first graphite is 90wt% to 99wt%.

15. The negative electrode according to claim 1, wherein, The weight ratio of the silicon-carbon composite to the first graphite is 2:98 to 40:

60.

16. The negative electrode according to claim 1, wherein, The negative electrode active material layer further includes at least one of a second graphite and a third graphite, wherein the second graphite is natural graphite and the third graphite has an aspect ratio different from that of the first graphite.

17. The negative electrode according to claim 16, wherein, The weight ratio of the first graphite to the second graphite or the third graphite is in the range of 8:2 to 5:

5.

18. The negative electrode according to claim 16, wherein, Based on a total weight of 100 wt% of the negative electrode active material layer, the amount of negative electrode active material in the negative electrode active material layer is 90 wt% to 99 wt%, and The negative electrode active material includes: the silicon-carbon composite; the first graphite; and at least one of the second graphite and the third graphite.

19. The negative electrode according to claim 1, wherein, The negative electrode active material layer also includes: Conductive materials; and Adhesive, The conductive material includes carbon-based materials, and The adhesive is a non-aqueous adhesive, an aqueous adhesive, a dry adhesive, or a combination thereof.

20. A rechargeable lithium battery, the rechargeable lithium battery comprising a negative electrode according to any one of claims 1-19.

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