Positive electrode active material for rechargeable lithium battery, positive electrode including the same, and rechargeable lithium battery including the positive electrode

Abstract

The present disclosure relates to a positive electrode active material for a rechargeable lithium battery, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode. The positive electrode active material includes a first particle including a compound Lia1Fex1B1y1PO4-b1 and having a first average particle diameter, and a second particle including a compound Lia2Nix2Coy2Mnz2Xc2O2-b2 and having a second average particle diameter larger than the first average particle diameter. A content (e.g., an amount) of the first particles in the positive electrode active material is greater than a content (e.g., an amount) of the second particles.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0056128, filed on April 26, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] One or more embodiments of this disclosure relate to positive electrode active materials for rechargeable lithium batteries, positive electrodes including positive electrode active materials, and rechargeable lithium batteries including positive electrodes. For example, this disclosure relates to positive electrode active materials including olivine-based lithium compounds, positive electrodes including olivine-based lithium compounds, and rechargeable lithium batteries including olivine-based lithium compounds. Background Technology

[0004] Recently, with the rapid popularity and widespread adoption of battery-powered electronic devices (such as mobile phones, laptops, and / or electric vehicles), the demand for batteries with relatively high energy density and capacity (e.g., rechargeable batteries) is increasing rapidly. Accordingly, research and development are actively underway to improve the performance of such rechargeable batteries (e.g., rechargeable lithium batteries).

[0005] A rechargeable lithium battery is a battery that includes a positive electrode and a negative electrode as well as an electrolyte. The positive electrode and the negative electrode contain active materials that can insert and extract lithium ions. The rechargeable lithium battery generates electrical energy through oxidation and reduction reactions when lithium ions are inserted into the positive electrode and the negative electrode and extracted from the positive electrode and the negative electrode (e.g., during the discharge process). Summary of the Invention

[0006] One or more aspects of embodiments of this disclosure relate to positive electrode active materials having high energy density, high operating voltage, and high conductivity.

[0007] One or more aspects of embodiments of this disclosure relate to rechargeable lithium batteries having high energy density, high operating voltage, and high and low temperature characteristics.

[0008] Other aspects will be set forth in part in the description which follows and in part will be obvious from the description or may be learned by practice of embodiments of this disclosure.

[0009] According to one or more embodiments of this disclosure, the positive electrode active material may include a first particle and a second particle, the first particle comprising a compound of Formula 1 and having a first average particle size, and the second particle comprising a compound of Formula 2 and having a second average particle size greater than the first average particle size. The content (e.g., amount) of the first particle may be greater than the content (e.g., amount) of the second particle.

[0010] Chemical Formula 1

[0011] Li a1 Fe x1 B 1 y1 PO 4-b1

[0012] In chemical formula 1, 0.8 ≤ a1 ≤ 1.2, 0.1 ≤ x1 ≤ 1.0, 0.001 ≤ y1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, x1 + y1 = 1, and B 1 It may include (for example) at least one element selected from the group consisting of titanium (Ti), magnesium (Mg), vanadium (V) and niobium (Nb).

[0013] Chemical formula 2

[0014] Li a2 Ni x2 Co y2 Mn z2 X c2 O 2-b2

[0015] In chemical formula 2, 0.8 ≤ a² ≤ 1.2, 0.8 ≤ x² ≤ 1.0, 0 ≤ y² ≤ 0.1, 0 ≤ z² ≤ 0.1, 0 ≤ c² ≤ 0.05, 0 ≤ b² ≤ 0.05, x² + y² + z² + c² = 1, and X may include (for example,) at least one element selected from the group consisting of aluminum (Al), titanium (Ti), magnesium (Mg), zirconium (Zr), molybdenum (Mo), and niobium (Nb).

[0016] According to one or more embodiments of this disclosure, the positive electrode for a rechargeable lithium battery may include a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material, a conductive material, and a binder.

[0017] According to one or more embodiments of the present disclosure, a rechargeable lithium battery may include: a positive electrode; a negative electrode including a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector; and a separator between the positive electrode and the negative electrode. Attached Figure Description

[0018] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this disclosure. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. Certain embodiments of the present disclosure and other aspects, features, and advantages will become more apparent from the following description taken in conjunction with the accompanying drawings.

[0019] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is provided.

[0020] Figures 2-5 Each illustration shows a simplified diagram of a rechargeable lithium battery according to one or more embodiments of the present disclosure, wherein Figure 2 Explaining cylindrical batteries, Figure 3 Explaining the prismatic battery, and Figure 4 and Figure 5 Each explains the bag-shaped or battery-like design.

[0021] Figure 6 An enlarged view illustrating the positive electrode active material layer of a rechargeable lithium battery according to one or more embodiments of the present disclosure is shown.

[0022] Figure 7A The illustration shows a scanning electron microscope (SEM) image of the positive electrode active material (first particle) of Example 1 of this disclosure.

[0023] Figure 7B The illustration shows a scanning electron microscope (SEM) image of the positive electrode active material (second particle) of Example 2 of this disclosure.

[0024] Figure 8 A graph illustrating the voltage-specific capacity characteristics of a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0025] Figure 9A and Figure 9B Each of the above diagrams illustrates the differential capacitance of a rechargeable lithium battery according to one or more embodiments of the present disclosure. Detailed Implementation

[0026] To fully understand the configurations and aspects of this disclosure, one or more embodiments of this disclosure will be described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the exemplary embodiments described below and may be implemented in one or more suitable forms. Rather, exemplary embodiments are provided merely to illustrate this disclosure and to enable those skilled in the art to fully understand its scope.

[0027] In this disclosure, it will be understood that if (e.g., when) an element is referred to as being on another element, then the element may be directly on the other element. Or an intermediary element may be present. In contrast, if (e.g., when) an element is referred to as being "directly on" another element, then no intermediary element is present. In the accompanying drawings, the dimensions (e.g., thickness) of some components may be enlarged for the purpose of effectively explaining the technical content. Throughout this disclosure, the same reference numerals refer to the same elements, and for the sake of brevity, their repeated descriptions are not provided.

[0028] Unless otherwise specifically stated in this disclosure, the singular forms “a,” “an,” and “described” are intended to include the plural forms as well. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure.” Additionally, unless otherwise specifically stated, the phrases “A or B,” “A and / or B,” or “A / B” may indicate “A but not B,” “B but not A,” and “A and B.” The terms “comprise(s)” and / or “comprising / including” as used in this disclosure do not exclude the presence or addition of one or more other components.

[0029] As used herein, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0030] Unless otherwise specifically defined in this disclosure, particle size / size may refer to average particle size / size. Furthermore, particle size / size refers to average particle size / size (D... 50 (), which refers to the diameter / size of particles whose cumulative volume accounts for approximately 50 vol% of the particle size distribution. D 50 The cumulative volume corresponds to the average diameter (or size) of 50 vol% of the particles in a particle size distribution (e.g., a cumulative distribution), and refers to the value corresponding to 50% of the particle sizes from the smallest particle in a distribution curve accumulated in order from the smallest to the largest particle size, when the total number of particles is 100%. Average particle size / size (D 50 The average particle size can be measured using methods well known to those skilled in the art, for example, by a particle size analyzer (e.g., a HORIBA LA-950 laser particle size analyzer), or by using transmission electron microscopy (TEM) images or scanning electron microscopy (SEM) images. In one or more embodiments, the average particle size / size can be measured using a measuring device employing dynamic light scattering, wherein data analysis is performed to count the number of particles for each particle size range, and the average particle size / size (D) can then be calculated. 50The laser scattering method can be used to measure the average particle size. In this method, target particles are dispersed in a dispersion medium, then a commercial laser diffraction particle diameter measuring instrument (e.g., Microtrac MT3000) is introduced, and ultrasonic waves at approximately 28 kHz are irradiated with an output of approximately 60 W. The average particle size (D) based on approximately 50% of the particle size distribution can be calculated within the measuring instrument. 50 In this disclosure, when the particles are spherical, "diameter" indicates the average particle size, and when the particles are non-spherical, "diameter" indicates the length of the major axis.

[0031] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure is provided. (Reference) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte (e.g., a liquid electrolyte) ELL.

[0032] The positive electrode 10 and the negative electrode 20 may be separated from each other by a diaphragm 30 (e.g., spaced apart or separated). The diaphragm 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the diaphragm 30 may be in contact with the electrolyte ELL. For example, the positive electrode 10, the negative electrode 20, and the diaphragm 30 may be immersed in the electrolyte ELL (e.g., impregnated with the electrolyte ELL).

[0033] The electrolyte ELL can be used as a medium for transferring lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move towards the positive electrode 10 or the negative electrode 20 through the separator 30.

[0034] Positive electrode 10

[0035] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 on the positive electrode current collector COL1. The positive electrode active material layer AML1 may include (e.g., in particulate form) a positive electrode active material and may further include a binder and / or a conductive material (e.g., an electronic conductor). Reference will be made later. Figure 6 This document provides a detailed description of the positive electrode active material layer AML1 according to one or more embodiments of the present disclosure. In one or more embodiments, aluminum (Al) foil may be used as the positive electrode current collector COL1, but the embodiments of the present disclosure are not limited thereto.

[0036] negative electrode 20

[0037] The negative electrode 20 for a rechargeable lithium battery may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 on the negative electrode current collector COL2. The negative electrode active material layer AML2 may include (e.g., in particulate form) negative electrode active material and may further include a binder and / or a conductive material (e.g., an electronic conductor).

[0038] For example, in one or more embodiments, based on a negative electrode active material layer of 100 wt%, the negative electrode active material layer AML2 may include about 90 wt% to about 99.5 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder, and about 0 wt% to about 5 wt% of conductive material.

[0039] The binder can be used to make the negative electrode active material particles adhere well to each other, and also to make the negative electrode active material adhere well to the negative electrode current collector COL2. The binder may include non-aqueous (e.g., water-insoluble) binders, aqueous (water-soluble) binders, dry binders and / or combinations thereof (e.g., any suitable combination).

[0040] Non-aqueous adhesives may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide and / or combinations thereof (e.g., any suitable combination).

[0041] 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, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol and / or combinations thereof (e.g., any suitable combination).

[0042] When an aqueous binder is used as a binder in the negative electrode active material layer AML2, it may further include a cellulose compound capable of 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 sodium (Na), potassium (K), or lithium (Li).

[0043] Dry adhesives can be fibrous polymeric materials. For example, dry adhesives can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide and / or combinations thereof (e.g., any suitable combination).

[0044] Conductive materials (e.g., electronic conductors) can be used to impart conductivity to electrodes. Any material that does not cause chemical changes and is an electronic conductive material can be used in the battery. Non-limiting examples of conductive materials can include: carbonaceous materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and / or carbon nanotube; metallic materials including copper, nickel, aluminum, silver, etc. and in the form of metal powder or metal fiber; conductive polymers (such as polyphenylene derivatives); and / or their mixtures (e.g., any suitable mixture).

[0045] The negative electrode current collector COL2 can use 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 (e.g., any suitable combination).

[0046] Negative electrode active material

[0047] The negative electrode active material in the negative electrode active material layer AML2 can include materials that can reversibly intercalate / deintercalate lithium ions, lithium metal, lithium metal alloys, materials capable of doping and dedoping lithium, or transition metal oxides.

[0048] Materials that can reversibly intercalate / deintercalate lithium ions can include carbonaceous negative electrode active materials, e.g., crystalline carbon, amorphous carbon, and / or their combination (e.g., any suitable combination). The crystalline carbon can be graphite such as amorphous (e.g., irregular shape), flaky, lamellar, spherical, or fibrous natural graphite and / or artificial graphite. The amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonized product, calcined coke, etc.

[0049] Lithium metal alloys include alloys of lithium and metals 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).

[0050] Materials capable of doping and dedoping lithium can be Si-based negative electrode active materials or Sn-based negative electrode active materials. Si-based negative electrode active materials can include silicon, silicon-carbon composites, SiO x (0 < x ≤ 2), Si-Q alloys (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 their combination (e.g., any suitable combination)) and / or their combination (e.g., any suitable combination). Sn-based negative electrode active materials can include Sn, SnO k (0 < k ≤ 2) (e.g., SnO2), Sn-based alloys, and / or their combination (e.g., any suitable combination).

[0051] The silicon-carbon composite can be a composite of silicon and amorphous carbon (e.g., in particulate form). According to one or more embodiments, the silicon-carbon composite can be in the form of silicon particles and amorphous carbon coated on the surface of each 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 a first coating (shell) of amorphous carbon on the surface of the secondary particles. Amorphous carbon may also be present between the primary silicon particles, and, for example, the primary silicon particles may each be coated with amorphous carbon. The secondary particles may be dispersed within the amorphous carbon matrix.

[0052] In one or more embodiments, the silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles, and a first coating of amorphous carbon on the surface of the core.

[0053] 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.

[0054] Diaphragm 30

[0055] Depending on the type or variety 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 a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof, such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polypropylene three-layer separator, a polypropylene / polypropylene / polypropylene three-layer separator, etc.

[0056] The diaphragm 30 may include a porous substrate and a first coating on the surface of the porous substrate (e.g., one surface or two surfaces (e.g., two opposite surfaces)), the first coating comprising an organic material, an inorganic material and / or a combination thereof (e.g., any suitable combination).

[0057] The porous substrate may be a polymer membrane formed from any one of the following polymers or copolymers or mixtures thereof: 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).

[0058] Organic materials may include polyvinylidene fluoride polymers and / or (meth)acrylic acid polymers.

[0059] 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 (e.g., any suitable combination), but embodiments of this disclosure are not limited thereto.

[0060] In one or more embodiments, organic and inorganic materials may be mixed in a first coating, or a coating comprising organic materials and a coating comprising inorganic materials may be stacked.

[0061] Electrolyte ELL

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

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

[0064] Non-aqueous organic solvents may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents and / or combinations thereof (e.g., any suitable combination).

[0065] Carbonate solvents may 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 may 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, ethylene glycol dimethyl ether, 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 nitrile solvents (such as R-CN (where R is a C2-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] Additionally, if (for example, when) a carbonate solvent is used, cyclic carbonates and chain carbonates can be mixed and used, and cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0070] Lithium salts dissolved in non-aqueous organic solvents supply lithium ions in rechargeable lithium batteries, ensuring basic operation and improving lithium ion transport and migration between the positive and negative electrodes. Lithium salts may 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+1 At least one of the following: SO2 (where x and y are integers from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0071] Rechargeable lithium batteries

[0072] Depending on their shape, rechargeable lithium batteries can be classified as cylindrical, prismatic, pouch-shaped, or coin-shaped or similar batteries. Figures 2-5 Each of the following 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 is shown as either a pouch-type or similar battery. (See reference) Figures 2-5 The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50 including the electrode assembly 40, the electrode assembly 40 including a separator 30 between a positive electrode 10 and a negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. In some embodiments, such as Figure 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of a sealed housing 50. In some embodiments, such as in 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 some embodiments, such as Figure 4 and Figure 5Each of the figures shows that the rechargeable lithium battery 100 may include electrode terminals 70, which may be, for example, a positive electrode terminal 71 and a negative electrode terminal 72, serving as an electrical path to guide the current formed in the electrode assembly 40 to the outside.

[0073] As a non-limiting example, rechargeable lithium batteries according to one or more embodiments can be used in vehicles, mobile phones and / or one or more suitable types (classes) of electronic devices.

[0074] Figure 6 This illustration shows an enlarged view of the positive electrode active material layer of a rechargeable lithium battery according to one or more embodiments of the present disclosure. (Reference) Figure 6 As discussed above, the positive electrode active material layer AML1 (see...) Figure 1 The material may include a first PTC1 particle, a second PTC2 particle, a conductive material CDM (e.g., an electronic conductor), and a binder BND. A plurality of first PTC1 particles and a plurality of second PTC2 particles may constitute a positive electrode active material according to one or more embodiments of the present disclosure.

[0075] In one or more embodiments, the positive electrode active material layer AML1 may further include components that can be used as a sacrificial positive electrode.

[0076] In one or more embodiments, the content (e.g., amount) of the positive electrode active materials PTC1 and PTC2 in the positive electrode active material layer AML1, relative to the total weight of about 100 wt% of the positive electrode active material layer AML1, can be in the range of about 90 wt% to about 99 wt%. The content of each of the binder BND and the conductive material CDM, relative to the total weight of about 100 wt% of the positive electrode active material layer AML1, can be about 0.5 wt% to about 5 wt%.

[0077] The adhesive BND can bond the first particle PTC1, the second particle PTC2, and the conductive material CDM together. For example, the adhesive BND may include at least one selected from the group consisting of: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, and nylon, but embodiments of this disclosure are not limited thereto.

[0078] Conductive material CDM can be used to improve the conductivity (e.g., electrical conductivity) of the positive electrode active material layer AML1. Any conductive material that does not cause a chemical change in the positive electrode active material layer AML1 can be used as a conductive material CDM, without limitation. For example, conductive material CDM may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers and / or carbon nanotubes; metallic materials containing copper, nickel, aluminum, silver, etc., and in the form of metal powder or metal fibers (e.g., in the form of metal powder or metal fibers); conductive polymers (such as polyphenylene derivatives); and / or mixtures thereof (e.g., combinations).

[0079] The following text will explain each of the first particle PTC1 and the second particle PTC2 in more detail.

[0080] First PTC1

[0081] The first particle PTC1 may have (e.g., be) a single particle form (e.g., a single particle / monolithic particle form). In this disclosure, a single particle may refer to a single particle or a single grain without internal grain boundaries. A single particle has a morphological phase and may refer to a single particle, an independent structure, a monolithic structure, or a non-aggregated particle, wherein the particle exists as a non-aggregated independent phase. For example, a single particle may be a single crystal. In one or more embodiments, a single particle may be a particle containing several crystals. In one or more embodiments, a single particle may be in an independently separated form. In one or more embodiments, a single particle may be in the form of 2 to 100 single particles attached to each other.

[0082] In one or more embodiments, the first particle PTC1 may be a nano-type or similar positive electrode active material. The first particle PTC1 may include at least one primary particle. In one or more embodiments, the first particle PTC1 may have a random form in which the primary particles are aggregated.

[0083] The first particle PTC1 can be provided in one or more suitable sizes. For example, in one or more embodiments, the average particle size (first average particle size) of the first particle PTC1 can be from about 500 nanometers (nm) to about 2.5 micrometers (μm) or about 1 μm. The minimum particle size of the first particle PTC1 (e.g., the smaller particle size of the first particle PTC1, i.e., as used herein, "first primary particle" refers to the first particle PTC1 whose size corresponds to the minimum particle size), i.e., the diameter of the primary particle can be from about 100 nm to about 500 nm or from about 200 nm to about 300 nm.

[0084] In one or more embodiments, the average particle size can be measured using a particle size analyzer. Average particle size (D) 50() can refer to the diameter of particles whose cumulative volume is about 50 vol% in the particle size distribution.

[0085] In one or more embodiments, the minimum particle size, i.e., the diameter of the primary particle, may refer to the diameter measured by randomly selecting about 30 primary particles from an electron microscope image of the first particle PTC1.

[0086] In one or more embodiments, the first PTC1 particle may include a first coating on its surface. The first particle includes a first coating containing carbon. The first coating may cover the entire surface of the first PTC1 particle or may cover a portion of the surface of the first PTC1 particle. For example, in one or more embodiments, the first coating may include elemental carbon and / or a carbon-containing compound. The first coating may further include at least one selected from the group consisting of titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds. The metal-containing compound (such as titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds) may be, for example, metal oxides, metal hydroxides, metal carbonates, synthetic compounds thereof, or mixtures thereof (e.g., any suitable mixture). The metal-containing compound may further include other metallic or non-metallic elements. For example, in one or more embodiments, the metal-containing compound may further include lithium. By including the first coating, the first PTC1 particle exhibits improved structural stability and improved electrical conductivity.

[0087] The first particle PTC1 may include an olivine-type lithium compound represented by chemical formula 1.

[0088] Chemical Formula 1

[0089] Li a1 Fe x1 B 1 y1 PO 4-b1

[0090] In chemical formula 1, the following conditions must be met: 0.8 ≤ a1 ≤ 1.2, 0.1 ≤ x1 ≤ 1.0, 0.001 ≤ y1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 = 1. B 1 It may include (for example) at least one element selected from the group consisting of Ti, Mg, V, and Nb. 1 This can be a dopant doped into the first PTC1 particle. For example, in one or more embodiments, B 1 It can be Ti.

[0091] In one or more embodiments, the first PTC1 particles may further include carbon elements derived from the first coating. Based on 100 wt% of the total weight of the first PTC1 particles, the carbon content (e.g., amount) in the first PTC1 particles may be about 0.5 wt% to about 5 wt%, about 0.5 wt% to about 3 wt%, about 0.5 wt% to about 2 wt%, or 1.5 wt% to 2.5 wt%.

[0092] Second PTC2 particle

[0093] The second PTC2 particle may be similar to the first PTC1 described above (e.g., in the form of a single particle) and have a single-particle form (e.g., a single-particle / monolithic particle form). The interpretation of a single particle may be the same as or similar to the previous interpretation of the first PTC1 particle. In one or more embodiments, the second PTC2 particle may be in the form of being composed of a single particle. In one or more embodiments, the second PTC2 particle may be in the form in which a plurality of single-particle NNP particles are attached to each other. Because the positive electrode active material according to this disclosure includes the second PTC2 particle having a single-particle form, a rechargeable lithium battery with high capacity and high energy density can be completed.

[0094] In one or more embodiments, the second PTC2 particles may include a second coating on their surface. By including the second coating, the second PTC2 particles can effectively suppress or reduce structural collapse due to repeated charging and discharging. Accordingly, the lifespan characteristics of the rechargeable lithium battery can be improved.

[0095] The second coating may include boron-containing compounds, aluminum-containing compounds, and / or combinations thereof (e.g., any suitable combination). The metal-containing compounds in the second coating (such as boron-containing compounds, aluminum-containing compounds, etc.) may be, for example, metal oxides, metal hydroxides, metal carbonates, synthetic compounds thereof, or mixtures thereof (e.g., any suitable mixture). The metal-containing compounds may further include other metallic or non-metallic elements. For example, in one or more embodiments, the second coating may further include lithium, manganese, and / or nickel.

[0096] Methods for measuring the content (e.g., amount) of metallic elements in the second coating of the second PTC2 particle may include scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis of the second PTC2 particle. This analysis can confirm the content of boron and / or aluminum in the second coating. In addition to SEM-EDS, methods for measuring the content (e.g., amount) of metallic elements in the second coating may include inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), etc.

[0097] The average particle size of the second particle PTC2 can be about 2 μm to about 15 μm, about 2 μm to about 10 μm, or about 2 μm to about 5 μm. The average particle size of the second particle PTC2 (the second average particle size) can be larger than the aforementioned average particle size of the first particle PTC1. If (for example, when) the second particle PTC2 comprises a plurality of individual particle NNPs (e.g., formed by a plurality of individual particle NNPs), the average size of the individual particle NNPs in each of the second particle PTC2 can be larger than the average particle size of the first particle PTC1.

[0098] In one or more embodiments, the particle size can be obtained by: randomly selecting approximately 30 second particles PTC2 from an electron microscope image of the positive electrode active material and measuring their diameters, or by using the diameters of particles whose cumulative volume is approximately 50 vol% in the particle size distribution as the average particle size (D). 50 ).

[0099] In one or more embodiments, the second PTC2 particle may include a lithium-nickel composite oxide as a nickel-based positive electrode active material. In one or more embodiments, the second PTC2 particle may include a high-nickel positive electrode active material containing a high content (e.g., amount) of nickel. High-nickel positive electrode active materials can achieve high capacity and high performance.

[0100] For example, in one or more embodiments, the second particle PTC2 may include a lithium-nickel composite oxide represented by chemical formula 2 having a layered structure.

[0101] Chemical formula 2

[0102] Li a2 Ni x2 Co y2 Mn z2 X c2 O 2-b2

[0103] In chemical formula 2, the following conditions must be met: 0.8 ≤ a² ≤ 1.2, 0.8 ≤ x² ≤ 1.0, 0 ≤ y² ≤ 0.1, 0 ≤ z² ≤ 0.1, 0 ≤ c² ≤ 0.05, 0 ≤ b² ≤ 0.05, and x² + y² + z² + c² = 1. X may include (for example, be) at least one element selected from the group consisting of Al, Ti, Mg, Zr, Mo, and Nb. X may be a dopant doped in the second particle PTC2.

[0104] Will refer again Figure 6The positive electrode active material according to one or more embodiments of the present disclosure is explained in more detail. The positive electrode active material of the present disclosure may include a first particle PTC1 and a second particle PTC2. The mixing ratio (e.g., weight ratio) of the first particle PTC1 to the second particle PTC2 in the positive electrode active material may be from about 90:10 to about 50:50. In one or more embodiments, the mixing ratio (e.g., weight ratio) of the first particle PTC1 to the second particle PTC2 in the positive electrode active material may be from about 90:10 to about 70:30. The content (e.g., amount) of the first particle PTC1 in the positive electrode active material may be greater than the content (e.g., amount) of the second particle PTC2.

[0105] Because the second PTC2 particle comprises a high-nickel positive electrode active material, a higher capacity can be achieved relative to the first PTC1 particle. That is, the inclusion of a high-nickel positive electrode active material in the second PTC2 particle compared to the first PTC1 particle allows for a higher capacity. In the positive electrode active material according to one or more embodiments of this disclosure, the first PTC1 particle and the second PTC2 particle are mixed in a suitable or appropriate ratio, and the capacity and operating voltage are improved compared to comparable lithium iron phosphate (LFP) batteries in the art.

[0106] Compared to the compound of Formula 1, the compound of Formula 2 (i.e., the high-nickel positive electrode active material) can have low electrical conductivity. In this disclosure, a second particle PTC2 as a single particle is used, which can improve conductivity and energy density.

[0107] The first PTC1 particle has the advantages of high stability and long lifespan. By using the structurally stable first PTC1 particle as the main material of the positive electrode active material, the relatively low stability and short lifespan of the second PTC2 particle can be compensated.

[0108] The positive electrode active material of this disclosure can improve the density, capacity, and energy density of the mixture by mixing a base of second PTC2 particles with a size of several micrometers with first PTC1 particles with a size of several hundred nanometers. In one or more embodiments, the powder compaction density of the positive electrode active material of this disclosure can be from about 2.0 g / cc to about 2.8 g / cc. Rechargeable lithium batteries incorporating the positive electrode active material of this disclosure can exhibit improved low-temperature characteristics.

[0109] Because the first PTC1 particle, being a single particle, has a small average particle size, a large amount of binder BND is expected or required to attach the first PTC1 particle to the positive electrode current collector COL1 (see...). Figure 1Because the positive electrode active material of this disclosure further includes a second particle PTC2 having a large average particle size and a first particle PTC1, the positive electrode active material layer AML1 can be smoothly and appropriately attached to the positive electrode current collector COL1. For example, in one or more embodiments, the content (e.g., amount) of the binder BND in the positive electrode active material layer AML1 can be reduced due to the second particle PTC2.

[0110] Rechargeable lithium batteries including positive electrode active materials according to one or more embodiments of the present disclosure (see Figure 1 During discharge at approximately 0.1C between approximately 2.5V and approximately 4.25V, an average voltage of approximately 3.2V to approximately 3.5V (i.e., 0.1C discharge voltage) can be observed. The average voltage is obtained by integrating the area under the discharge voltage curve (voltage-capacity plot) after the initial charge and discharge of the battery cell, and then dividing the integral by the discharge capacity. Furthermore, in the differential capacitance (dQ / dV)-voltage charging plot of the rechargeable lithium battery of this disclosure, the number of charging peaks (e.g., the number of charging peaks) appearing at voltages between approximately 3.55V and approximately 4.25V can be 3 to 5. In this plot, the ratio (IB / IA) of the intensity of peak B (IB) appearing at voltages between approximately 4.1V and approximately 4.25V to the intensity (IA) of peak A (IA) appearing at voltages between approximately 3.41V and approximately 3.55V) can be approximately 0.005 to approximately 0.008.

[0111] Methods for preparing positive electrode active materials

[0112] The method for preparing the first PTC1 particle according to one or more embodiments of this disclosure will be explained in more detail. An iron phosphate precursor, a lithium source, a carbon source, and a dopant source may be added to and mixed in a solvent. For example, the solvent may be water, ethanol, etc. The iron phosphate precursor may be a compound containing both iron (Fe) and phosphorus (P) (e.g., simultaneously), or a mixture of an iron (Fe)-containing compound and a phosphorus (P)-containing compound (e.g., any suitable mixture). For example, in one or more embodiments, the iron phosphate precursor may include FePO4·H2O and / or a mixture of FeSO4 and H3PO4 (e.g., any suitable mixture).

[0113] The lithium source may include at least one selected from the group consisting of: lithium oxide, lithium hydroxide, lithium chloride, lithium nitrate, lithium nitrite, lithium formate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, and lithium citrate.

[0114] Carbon sources may include at least one selected from the group consisting of glucose, sucrose, fructose, cellulose, starch, citric acid, polyacrylic acid, polyethylene glycol, and dopamine.

[0115] The dopant source may include oxides containing a doped metal / element and / or chlorides containing a doped metal / element. For example, in one or more embodiments, the dopant source may include at least one selected from the group consisting of titanium oxide, magnesium oxide, vanadium oxide, and niobium oxide.

[0116] The mixture can be wet-milled. A suitable wet mill capable of temperature control can be used for wet milling. For example, wet milling can use at least one selected from the group consisting of: bead mills, ball mills, grinding mills, vertical bead mills (apex mills), super mills, and basket mills. Through the wet milling process, the particles in the mixture can be ground to a fine size.

[0117] A dry mixture can be formed by removing the solvent from the mixture. In one or more embodiments of this disclosure, the formation of a dry mixture may include direct evaporation of the mixture. For example, direct evaporation may include static drying or spray drying.

[0118] The dried mixture can then be baked under an inert atmosphere. The inert atmosphere can be nitrogen and / or argon. The baking temperature can be approximately 500°C to approximately 1000°C or approximately 600°C to approximately 800°C. The baking time can be approximately 4 hours to approximately 20 hours or approximately 6 hours to approximately 12 hours. Through baking the dried mixture, first particles of PTC1 comprising a compound of formula 1 can be formed.

[0119] The first PTC1 particles after baking can be subjected to a dry grinding process. As a result, the first PTC1 particles can have the following properties: Figure 6 The single-particle form shown (e.g., in the form of a single particle).

[0120] The method for preparing second PTC2 particles according to one or more embodiments of this disclosure will be explained in more detail. A high-nickel precursor may be prepared. The high-nickel precursor may include Ni as presented in Chemical Formula 2 above. The Ni content (e.g., amount) may be greater than about 80 at% relative to the total metal element content (e.g., amount) in the high-nickel precursor. In one or more embodiments, the high-nickel precursor may further include Co and Mn elements.

[0121] In one or more embodiments, high-nickel precursors can be obtained by a co-precipitation method. For example, the co-precipitation method may include: dissolving a transition metal feedstock in a solvent such as distilled water, and continuously adding a transition metal salt solution together with a chelating agent and an alkaline aqueous solution to a reactor to produce a precipitate. After collecting the precipitate in a slurry or similar form, the slurry solution can be filtered and dried to obtain a high-nickel precursor (i.e., a metal composite oxide / hydroxide).

[0122] In this disclosure, the transition metal feedstock may include a metal salt of Ni. In one or more embodiments, the transition metal feedstock may further include at least one salt of a metal selected from Co and Mn. The metal salt may include sulfates, nitrates, acetates, halides, hydroxides, etc., and any one of them may be used as long as it is soluble in a solvent. The transition metal feedstock according to one or more embodiments may include nickel salts, cobalt salts, and manganese salts. The transition metal feedstock can be blended by controlling the molar ratio so that the high-nickel precursor can have a Ni element content (e.g., amount) of about 80 at% or greater.

[0123] The high-nickel precursor and the lithium source can then be mixed in a certain proportion to form a mixture. For example, in one or more embodiments, the high-nickel precursor and the lithium source can be mixed in a molar ratio of about 1:1. The lithium source may include at least one selected from the group consisting of: lithium oxide, lithium hydroxide, lithium chloride, lithium nitrate, lithium nitrite, lithium formate, lithium acetate, lithium oxalate, lithium carbonate, lithium phosphate, dilithium hydrogen phosphate, lithium dihydrogen phosphate, and lithium citrate.

[0124] By removing the solvent from the mixture, a dry mixture can be formed. The dry mixture can then be baked. The baking temperature can be about 700°C to about 1000°C or about 900°C to about 1000°C. The baking process can be carried out in an oxidizing atmosphere (such as air and oxygen). The heating time of the baking process can be about 10 hours to about 30 hours. In one or more embodiments of this disclosure, a preliminary baking can be further performed at about 150°C to about 800°C before the baking process.

[0125] In one or more embodiments of this disclosure, a baking process may be performed after additionally adding a flux to the mixture. The flux may be a compound containing at least one metal selected from the group consisting of Zr, La, S, and Nb. By using the flux, the second PTC2 particles can be readily formed into a single particle form. Additionally, the average particle size of the second PTC2 particles can be increased.

[0126] A second PTC2 particle can be formed from a mixture containing a high-nickel precursor and a lithium source through a baking process. The synthesized second PTC2 particle can then be subjected to a grinding process.

[0127] In one or more embodiments, the ground second PTC2 particles may be coated. For example, the second PTC2 particles and a coating material may be added to a solvent and mixed. The coating material may include boron and / or aluminum. After filtering and drying the second PTC2 particles, a surface treatment may be performed. The surface treatment may include a heating process in an oxidizing atmosphere (such as air and oxygen). The surface treatment may be performed at a temperature of about 500°C to about 800°C.

[0128] In one or more embodiments of this disclosure, the coating process may include a dry coating process. For example, second PTC2 particles and the coating material may be placed in a dry coating apparatus and mixed by stirring without solvent. The resulting dry mixture may be surface treated.

[0129] The positive electrode active material according to the present disclosure can be prepared by mixing the first PTC1 particles and the second PTC2 particles prepared by the above method. The first PTC1 particles and the second PTC2 particles can be mixed in a weight ratio of about 90:10 to about 50:50 or about 90:10 to about 70:30.

[0130] Carbon elemental analysis according to one or more embodiments of this disclosure can be performed using an Elementar Micro Cube elemental analyzer. The specific operating methods and conditions are as follows: A sample weighing approximately 1 mg to 2 mg is weighed in a tin cup, placed in an automatic sampling tray, and introduced into a combustion tube through a ball valve. Combustion is then carried out at a combustion temperature of approximately 1000°C. Subsequently, the combustion gases are reduced using copper to form carbon dioxide. The carbon dioxide is detected using a thermal conductivity detector (TCD).

[0131] In one or more embodiments of the present disclosure, a method for measuring carbon content (e.g., amount) is performed on the surface of the particles using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and quantitative analysis is conducted. In addition to SEM-EDS, methods for measuring carbon content (e.g., amount) may include inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), etc.

[0132] The following describes embodiments and comparative examples. However, the embodiments are merely illustrative of this disclosure, and this disclosure is not limited to the embodiments.

[0133] Example 1: Preparation of the first particle in single-particle form

[0134] A FePO4·H2O iron phosphate precursor with an iron to lithium molar ratio of approximately 1:1.03 was mixed with lithium carbonate, approximately 2500 ppm titanium dioxide, and approximately 8 wt% glucose in water. The mixture was subjected to a wet milling process by ball milling. The mixture was evaporated and dried in a heated furnace tray, and then placed in a vacuum oven and dried at approximately 85°C for approximately 4 hours. The dried mixture was baked in a nitrogen atmosphere at approximately 650°C for approximately 10 hours. The baked product was milled to obtain first particles in the form of single particles (e.g., in the form of single particles). The average size of the first particles (first average particle size) was approximately 1 μm.

[0135] Example 2: Preparation of a second particle in single-particle form

[0136] High-nickel precursors were prepared using a co-precipitation method. For example, nickel sulfate (NiSO4·6H2O), cobalt sulfate (CoSO4·7H2O), and manganese sulfate (MnSO4·H2O) in a molar ratio of approximately 93:5:2 were dissolved in distilled water as a solvent to prepare a metal raw material mixture solution. Then, the metal raw material mixture solution, ammonia, and sodium hydroxide were added to a reactor and reacted. The slurry solution in the reactor was filtered and washed with high-purity distilled water. The washed material was dried in a hot air oven at approximately 210°C for approximately 24 hours to obtain a small-particle precursor (NiSO4·6H2O) with an average particle size of approximately 4 μm. 0.93 Co 0.05 Mn 0.02 (OH)2) powder.

[0137] The high-nickel precursor and anhydrous lithium hydroxide (LiOH) were dry-mixed using a Henschel mixer. The mixing was performed such that the molar ratio of lithium to transition metal was approximately 1:1. The transition metal was the sum of the transition metals (Ni + Co + Mn) contained in the high-nickel precursor. A flux was additionally added to the mixture, and the mixture was heat-treated at approximately 750°C in an oxygen atmosphere for approximately 15 hours (i.e., a baking process) to synthesize a second particle as the active material for the high-nickel positive electrode. The second particle was then milled using a jet mill at a pressure of approximately 3 bar.

[0138] The second particle was added to distilled water and rinsed. Approximately 3 mol% of boron oxide and aluminum oxide, corresponding to the total amount of transition metals based on the second particle, were added for boron and aluminum coating. The coated second particle was dried at approximately 150°C for approximately 12 hours and then heated at approximately 700°C (i.e., surface treatment) in an oxygen atmosphere for approximately 15 hours.

[0139] Example 3-1: Preparation of a mixture of the first and second particles

[0140] The first particle from Example 1 and the second particle from Example 2 were mixed at a mass ratio of approximately 9:1 to prepare the positive electrode active material.

[0141] Example 3-2: Preparation of a mixture of the first and second particles

[0142] The first particle from Example 1 and the second particle from Example 2 were mixed at a mass ratio of approximately 8:2 to prepare the positive electrode active material.

[0143] Example 3-3: Preparation of a mixture of the first and second particles

[0144] The first particle from Example 1 and the second particle from Example 2 were mixed at a mass ratio of approximately 7:3 to prepare the positive electrode active material.

[0145] Examples 3-4: Preparation of a mixture of the first and second particles

[0146] The first particle from Example 1 and the second particle from Example 2 were mixed at a mass ratio of approximately 6:4 to prepare the positive electrode active material.

[0147] Examples 3-5: Preparation of a mixture of the first and second particles

[0148] The first particle from Example 1 and the second particle from Example 2 were mixed at a mass ratio of approximately 5:5 to prepare the positive electrode active material.

[0149] Manufacturing of positive electrode

[0150] A positive electrode active material slurry was prepared by mixing 95 wt% of the final positive electrode active material, 3 wt% of polyvinylidene fluoride binder, and 2 wt% of carbon black conductive material in an N-methylpyrrolidone solvent. The positive electrode active material slurry was then applied to an aluminum current collector, dried, and rolled to fabricate the positive electrode.

[0151] Manufacturing of negative electrode

[0152] Graphite, a binder (PVDF), and a conductive material (carbon black) were mixed in an N-methylpyrrolidone solvent at a weight ratio of 95:3:2 to prepare a negative electrode active material slurry. The negative electrode active material slurry was applied to a copper current collector, dried, and rolled to manufacture the negative electrode.

[0153] Preparation of rechargeable lithium batteries

[0154] The prepared positive and negative electrodes were used to form a coin-shaped full cell. A polypropylene membrane (Celgard 3510) was used as the separator. As the electrolyte, an electrolyte obtained by mixing 1.3M LiPF6 with a mixed solvent of ethylene carbonate (EC): diethyl carbonate (DEC): fluoroethylene carbonate (FEC) (volume ratio of 2:6:2) was used.

[0155] Evaluation Example 1: Surface Analysis of Positive Electrode Active Material

[0156] Scanning electron microscope (SEM) image of the first particle prepared in Example 1. Figure 7A The image is shown in [the image]. The SEM image of the second particle prepared in Example 2 is shown in [the image]. Figure 7B As shown in the image. (Reference) Figure 7A It can be confirmed that the first particle according to one or more embodiments of this disclosure has a fine, single-particle form at the nanoscale. (See reference...) Figure 7BIt can be confirmed that the second particle according to one or more embodiments of this disclosure has a single particle form with a micrometer size. It can be confirmed that the second particle has a single particle form or a plurality of single particles attached to each other. That is, the first particle is shown as a fine single particle form with a nanometer size. Figure 7A The second particle is characterized by having a single particle form with a micrometer size. Figure 7B Additionally, the second particle can be a single particle or an aggregate of multiple single particles.

[0157] Evaluation Example 2: Evaluation of Positive Electrode Active Material

[0158] The average particle size (D) of the positive electrode active materials in Examples 1, 2, 3-1, 3-2, 3-2, 3-4, and 3-5 was measured. 50 The powder compaction density (PD) and the results are shown in Table 1.

[0159] Table 1

[0160] <![CDATA[D 50 (μm)]]> PD (g / cc) Example 1 1.0 2.43 Example 2 3.1 2.98 Example 3-1 1.3 2.68 Example 3-2 1.4 2.71 Example 3-3 1.5 2.77 Examples 3-4 1.7 2.62 Examples 3-5 1.9 2.59

[0161] Referring to Table 1, the average particle size (D) of the positive electrode active material in Example 1 can be confirmed. 50 Compared to the positive electrode active materials of Examples 3-1 to 3-5 of this disclosure, the average particle size (D) of each of them is significantly smaller. 50 The powder compaction density of the positive electrode active material in Examples 3-1 to 3-5 was significantly increased compared to that of the positive electrode active material in Example 1.

[0162] Evaluation Example 3: Evaluation of Battery Characteristics

[0163] The characteristics of each of the rechargeable lithium batteries prepared using the corresponding positive electrode active materials of Examples 1, 2, 3-1, 3-2, 3-3, 3-4 and 3-5 were evaluated.

[0164] At 25°C, each rechargeable lithium battery was initially charged under constant current (approximately 0.1C) and constant voltage (approximately 4.25V (i.e., charging voltage), approximately 0.01C cutoff) conditions, and then allowed to rest for approximately 10 minutes before being discharged to approximately 2.5V under constant current (approximately 0.1C) conditions to obtain the initial charge capacity and initial discharge capacity (0.1C discharge capacity (mAh / g)). Then, at approximately -20°C, the batteries were charged at approximately 0.2C and constant voltage (approximately 4.25V, approximately 0.01C cutoff) conditions and discharged at approximately 0.2C until approximately 2.5V, and the -20°C discharge capacity was measured. The average voltage (0.1C discharge voltage (V)) was obtained by integrating the area under the discharge voltage curve (voltage-capacity plot) after the initial charge and discharge of each battery cell and then dividing the integral by the discharge capacity. For rechargeable lithium batteries using the positive electrode active material according to the embodiments or comparative examples, the charge and discharge capacity per weight (mAh / g) is measured and multiplied by the powder compaction density (g / cc) to obtain the volume capacity per unit volume (mAh / cc) of the rechargeable lithium batteries according to the embodiments and comparative examples.

[0165] The lifetime of a rechargeable lithium battery was evaluated by repeating 50 charge-discharge cycles at approximately 45°C under conditions of approximately 2.5V to 4.25V and approximately 1C (approximately 4.25V, approximately 0.05C cutoff) / 1C (approximately 2.5V, approximately 1C cutoff). The capacity retention rate (i.e., 45°C lifetime) at approximately 45°C was calculated by dividing the capacity at the 50th discharge cycle by the initial discharge capacity. The evaluation results of the battery characteristics are shown in Table 2.

[0166] Table 2

[0167]

[0168] Referring to Table 2, it can be confirmed that, compared with the rechargeable battery according to Example 1, all rechargeable batteries according to Examples 3-1 to 3-5 exhibit a significant increase in voltage and capacity. Furthermore, it can be confirmed that, compared with the rechargeable battery according to Example 2, all rechargeable batteries according to Examples 3-1 to 3-5 exhibit excellent or adequate lifespan characteristics at approximately 45°C.

[0169] The voltage-specific capacity characteristics of each of the rechargeable batteries prepared using the corresponding positive electrode active materials of Examples 1, 3-1, and 3-2 were measured. Figure 8 As shown in the image. (Reference) Figure 8 It can be confirmed that, compared with the rechargeable battery according to Example 1, the rechargeable lithium batteries according to Examples 3-1 and 3-2 each exhibit increased voltage and capacity.

[0170] The differential capacitance of each of the rechargeable lithium batteries prepared using the corresponding positive electrode active materials of Examples 1, 3-1 and 3-2 was evaluated.

[0171] Each of the rechargeable lithium batteries is first charged and discharged at approximately 0.1C, and then charged and discharged a second time in the same manner. Figure 9A To measure and plot the differential capacitance (dQ / dV)-voltage charging curve, and Figure 9B A graph showing the differential capacitance (dQ / dV)-voltage charging curve is provided by only discharging a portion of the voltage range of approximately 2.5 to approximately 4.3V.

[0172] refer to Figure 9B It can be confirmed that for each of the rechargeable batteries according to Examples 3-1 and 3-2, the number of charging peaks (e.g., the number of charging peaks) observed at voltages between approximately 3.55V and approximately 4.25V is three or more. In contrast, only one peak was confirmed within the voltage range of the rechargeable battery according to Example 1.

[0173] refer to Figure 9A It can be confirmed that each of the rechargeable batteries according to Examples 3-1 and 3-2 shows that the ratio (IB / IA) of the intensity of peak B between about 4.1V and about 4.25V to the intensity (IA) of peak A between about 3.41V and about 3.55V is about 0.0062.

[0174] In the positive electrode active material according to this disclosure, a first olivine-like particle matrix with a size of hundreds of nanometers is mixed with a layered second particle with a size of several micrometers, which improves the density, capacity, and energy density of the mixture. Even with a relatively small amount of binder, the positive electrode active material layer according to this disclosure can be smoothly attached to the positive electrode current collector. The rechargeable lithium battery according to this disclosure can have a relatively high average voltage.

[0175] In this disclosure, expressions such as "at least one of," "one of," and "selected from" modify the entire list of elements, not individual elements, when placed before / after a list of elements. For example, "at least one of a, b, and c," "selected from at least one of a, b, and c," "selected from at least one of a to c," etc., can indicate only a, only b, only c, (e.g., both a and b simultaneously), (e.g., both a and c simultaneously), (e.g., both b and c simultaneously), all of a, b, and c, or variations thereof. Depending on the context, the " / " used herein can be interpreted as "and" or "or."

[0176] In the context of this disclosure, unless otherwise specified, the terms “use,” “using,” and “used” are to be regarded as synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively.

[0177] 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").

[0178] As used herein, the terms “substantially,” “about,” and similar terms are used as approximations rather than terms of degree and are intended to include inherent biases in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. “About” or “approximation” as used herein also includes stated values ​​and means within an acceptable range of deviation for a particular value, determined by one of ordinary skill in the art considering the measurement in question and the errors associated with the measurement of the particular quantity (i.e., limitations of the measurement system). For example, “about” may mean within one or more standard deviations of a stated value, or within ±30%, ±20%, ±10%, or ±5% of the stated value.

[0179] Any numerical range set forth herein is intended to include all subranges with the same numerical precision that fall within the set forth range. For example, the range “1.0 to 10.0” is intended to include (and inclusive) the stated minimum value of 1.0 and the stated maximum value of 10.0, that is, all subranges having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limit set forth herein is intended to include all lower numerical limits covered therein, and any minimum numerical limit set forth in this specification is intended to include all higher numerical limits covered therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly set forth any subranges that fall within the range expressly set forth herein.

[0180] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components described herein according to embodiments of the present invention may 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 may be formed on an integrated circuit (IC) chip or on a separate IC chip. Furthermore, various components of the apparatus may be implemented on a flexible printed circuit film, a tape-on-a-chip (TCP), or a printed circuit board (PCB), or formed on a substrate. Furthermore, various components of the apparatus may be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components to perform the various functions described herein. The computer program instructions are stored in memory, which may be implemented using standard storage devices (e.g., random access memory (RAM)) in the computing device. The computer program instructions may also be stored in other non-transitory computer-readable media (e.g., CD-ROMs or flash drives). Furthermore, those skilled in the art should recognize that, without departing from the scope of this disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a dedicated computing device may be distributed across one or more other computing devices.

[0181] Those skilled in the art will recognize that, in view of the overall content of this disclosure, each suitable feature of the various embodiments of this disclosure may be combined in part or in whole, or combined with each other, 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 of each other or in combination with each other in any suitable way.

[0182] Although one or more embodiments of this disclosure have been described, it should be understood that this disclosure is not limited to these embodiments, and those skilled in the art can make one or more appropriate changes and modifications within the spirit and scope of the claimed disclosure and its equivalents.

Claims

1. A positive electrode active material, comprising: Multiple first particles, each comprising a compound of chemical formula 1 and having a first average particle size; and Multiple second particles, each comprising a compound of chemical formula 2 and having a second average particle size greater than the first average particle size, The content of the first particle is greater than the content of the second particle. Chemical Formula 1 Li a1 Fe x1 B 1 y1 PO 4-b1 In chemical formula 1, 0.8 ≤ a1 ≤ 1.2, 0.1 ≤ x1 ≤ 1.0, 0.001 ≤ y1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, x1 + y1 = 1, and B 1 It is selected from at least one element in the group consisting of Ti, Mg, V and Nb, and Chemical formula 2 Li a2 Ni x2 Co y2 Mr z2 X c2 O 2-b2 In chemical formula 2, 0.8≤a²≤1.2, 0.8≤x²≤1.0, 0≤y²≤0.1, 0≤z²≤0.1, 0≤c²≤0.05, 0≤b²≤0.05, x²+y²+z²+c²=1, and X is at least one element selected from the group consisting of Al, Ti, Mg, Zr, Mo and Nb.

2. The positive electrode active material according to claim 1, wherein the weight mixing ratio of the first particle to the second particle is 90:10 to 70:

30.

3. The positive electrode active material according to claim 1, wherein each of the first particle and the second particle is in the form of a single particle.

4. The positive electrode active material according to claim 1, The second particle has the form in which multiple individual particles are attached to each other, and The first average particle size is smaller than the average particle size of the single particle.

5. The positive electrode active material according to claim 1, The first particle includes a first coating containing carbon elements, and Based on the first particle with a total weight of 100 wt%, the carbon content in the first particle is 1.5 wt% to 2.5 wt%.

6. The positive electrode active material according to claim 1, The second particle includes a second coating, and The second coating comprises a boron-containing compound, an aluminum-containing compound, or a combination thereof.

7. The positive electrode active material according to claim 1, wherein the first average particle size is 500 nm to 2.5 μm.

8. The positive electrode active material according to claim 1, wherein the second average particle size is 2 μm to 5 μm.

9. The positive electrode active material according to claim 1, wherein the powder compaction density of the positive electrode active material is 2.0 g / cc to 2.8 g / cc.

10. A positive electrode, the positive electrode comprising: Positive electrode current collector; and The positive electrode active material layer is located on the positive electrode current collector. The positive electrode active material layer comprises the positive electrode active material, conductive material, and binder according to any one of claims 1 to 9.

11. The positive electrode according to claim 10, wherein the binder content is 0.5 parts by weight to 5 parts by weight based on 100 parts by weight of the positive electrode active material layer.

12. The positive electrode of claim 10, wherein the binder comprises at least one selected from the group consisting of: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, and nylon.

13. The positive electrode according to claim 10, wherein the content of the conductive material is 0.5 parts by weight to 5 parts by weight, based on 100 parts by weight of the positive electrode active material layer.

14. The positive electrode according to claim 10, wherein the conductive material comprises: Carbon-based materials, including natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofibers and / or carbon nanotubes; Metallic materials, including copper, nickel, aluminum and / or silver, and in the form of metal powder or metal fibers; Conductive polymers, including polyphenylene derivatives; or Its mixture.

15. A rechargeable lithium battery, comprising: The positive electrode according to claim 10114; The negative electrode includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector; as well as A diaphragm is located between the positive electrode and the negative electrode.

16. The rechargeable lithium battery of claim 15, wherein the average voltage during discharge at 0.1C between 2.5V and 4.25V is 3.2V to 3.5V.

17. The rechargeable lithium battery according to claim 15, wherein the number of charging peaks appearing at a voltage between 3.55V and 4.25V in the differential capacitance-voltage charging diagram is 3 to 5.

18. The rechargeable lithium battery according to claim 15, wherein in the differential capacitance-voltage charging diagram, the ratio of the intensity of peak B appearing at a voltage between 4.1V and 4.25V to the intensity of peak A appearing at a voltage between 3.41V and 3.55V is 0.005 to 0.008.

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