Positive electrode active material and rechargeable lithium battery including same

Abstract

The invention relates to a positive electrode active material and a rechargeable lithium battery including the same. The positive electrode active material includes first particles containing a compound represented by Chemical Formula 1 and having a first average particle diameter: Chemical Formula 1 Lia1Mnx1Fey1Bz1PO4-b1 wherein in Chemical Formula 1, 0.8 < = a1 < = 1.2, 0.45 < = x1 < = 0.55, 0.45 < = y1 < = 0.55, 0lt; x < = 1, y < = 1, z < = 0.05, 0 < = b1 < = 0.05, and x1 + y1 + z1 = 1, and B is Mg and Ti.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0053612 filed on April 22, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Embodiments of the present disclosure described herein relate to a positive electrode active material and a rechargeable lithium battery including the positive electrode active material, and for example, to a positive electrode active material containing an olivine-based lithium compound and a rechargeable lithium battery including the positive electrode active material. Background Art

[0004] Recently, with the rapid popularization of electronic devices (such as mobile phones and / or laptop computers) and / or electric vehicles using batteries, the demand or expectation for rechargeable batteries having relatively high energy density and relatively high capacity has increased significantly. Accordingly, extensive research and development efforts have been devoted to enhancing (improving) the performance of rechargeable batteries (such as rechargeable lithium batteries).

[0005] Rechargeable lithium batteries consist of a positive electrode and a negative electrode (each containing an active material capable of intercalating and deintercalating lithium ions) and an electrolyte. When lithium ions are intercalated and deintercalated between the positive and negative electrodes, electrical energy is generated (produced) through oxidation and reduction reactions. Summary of the Invention

[0006] Aspects according to one or more embodiments of the present disclosure relate to a positive electrode active material with (having) high energy density, high operating voltage (hereinafter, average voltage), high conductivity, and high mixture density.

[0007] Aspects according to one or more embodiments of the present disclosure are directed to a rechargeable lithium battery with (having) high energy density, high operating voltage, high charge and discharge efficiency, and long lifespan.

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

[0009] In one or more embodiments of the present disclosure, the positive electrode active material may include first particles containing a compound represented by Chemical Formula 1 and having a first average particle size:

[0010] Chemical formula 1

[0011] Li a1 Mn x1 Fe y1 Bz1 PO 4-b1

[0012] In the above Chemical Formula 1, 0.8≤a1≤1.2, 0.45≤x1≤0.55, 0.45≤y1≤0.55, 0

[0013] B can be Mg and Ti.

[0014] In one or more embodiments of the present disclosure, the positive electrode active material can include first particles containing a compound represented by Chemical Formula 2 and having a first average particle diameter, and the first particles can be doped with Mg and Ti, and the total doping amount of Mg and Ti can be about 2500 ppm to about 5000 ppm:

[0015] Chemical Formula 2

[0016] Li a2 Mn x2 Fe y2 PO 4-b2

[0017] In Chemical Formula 2, 0.8≤a2≤1.2, 0.45≤x2≤0.55, 0.45≤y2≤0.55, 0≤b2≤0.05, and x2+y2=1 can be satisfied.

[0018] In one or more embodiments of the present disclosure, the rechargeable lithium battery can include a positive electrode having a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, a negative electrode having 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, and a differential capacity (dQ / dV)-voltage charge profile of the rechargeable lithium battery can include a first charge peak (V1) at a voltage of about 3.4 V to about 4.0 V, a first discharge peak (V2) at a voltage of about 3.4 V to about 4.0 V, and a second charge peak (V3) at a voltage of about 4.0 V to about 4.4 V. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure. In the drawings:

[0020] Figure 1 To illustrate the concept of a rechargeable lithium battery according to one or more embodiments of the present disclosure;

[0021] Figures 2-5to each illustrate a schematic view of a rechargeable lithium battery according to one or more embodiments, Figure 2 to show a prismatic battery, Figure 3 to show a prismatic battery, and Figure 4 and Figure 5 to show a pouch-type battery;

[0022] Figure 6 and Figure 7 to each illustrate a magnified view of a positive electrode active material layer of a rechargeable lithium battery according to one or more embodiments of the present disclosure;

[0023] Figure 8 to show a flowchart of a method of preparing a positive electrode active material according to one or more embodiments of the present disclosure;

[0024] Figure 9 and Figure 10 to show a scanning electron microscope (SEM) image of a positive electrode active material according to one or more embodiments of the present disclosure;

[0025] Figure 11 to show a SEM image of a positive electrode active material according to Comparative Example 1 of the present disclosure; and

[0026] Figure 12 to show a graph of a differential capacity (dQ / dV)-voltage charging curve measured once according to Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0027] In order to fully understand the configuration and effects of the present disclosure, embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. However, the present disclosure can be implemented in one or more suitable forms, and should not be construed as being limited to one or more embodiments set forth herein, and one or more appropriate changes and modifications can be made. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art to which the present disclosure pertains.

[0028] In the present specification, it will be understood that, if (for example, when) an element is referred to as being (for example, when) on another element, it can be directly on the other element or an intervening element can be present therebetween. In the drawings, the thickness of components is exaggerated for effective explanation of the technical content. The same reference numbers or symbols refer to the same elements throughout the specification, and a repeated description thereof can not be provided in the specification.

[0029] The embodiments described herein will be explained in greater detail with reference to sectional and / or plan views that are examples of illustrations of the present disclosure. In the drawings, the dimensions (e.g., thicknesses) of the films and regions are exaggerated for effective explanation of the technical content. Accordingly, the regions illustrated in the drawings have a schematic nature and the shapes of the regions illustrated in the drawings are intended to illustrate the specific shapes of the regions of the device and are not intended to limit the scope of the present disclosure. In one or more appropriate embodiments of the present specification, terms such as "first", "second", and "third" are used to describe one or more appropriate components, but these components should not be limited by these terms. These terms are used only to distinguish one component from another component. The embodiments described and illustrated herein also include their complementary embodiments.

[0030] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, expressions such as "at least one of," "one of," and "selected from the group of," when preceding the list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, "at least one of a, b, and c," "at least one selected from a, b, and c," and the like, can indicate a, only b, only c, both a and b (e.g., at the same time), both a and c (e.g., at the same time), both b and c (e.g., at the same time), all of a, b, and c, or variations thereof.

[0031] The terms used in the present specification are used to describe the embodiments and are not intended to limit the present disclosure. In the present specification, the singular forms are intended to include the plural forms, unless the context clearly indicates otherwise. The terms "comprises" and / or "comprising," and / or "includes" and / or "including" when used in this specification, do not exclude the presence of one or more other components.

[0032] In the present specification, "combinations thereof" can refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of components.

[0033] Unless otherwise defined in the present specification, the particle size can be the average particle size. When the particles are spherical, "size" or "diameter" indicates the particle size or the average particle size, and when the particles are non-spherical, "size" or "diameter" indicates the length of the long axis or the average length of the long axis. Also, the particle size refers to the average particle size (D 50 ), which refers to the diameter of the particles at about 50% of the cumulative volume in the particle size distribution. The average particle size (D 50) can be measured by a method appropriate to those skilled in the art, for example, it can be measured by a particle size analyzer, or it can also be measured using a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. In one or more embodiments, the average particle size is measured by a measuring device using dynamic light scattering, wherein the number of particles in each particle size range is counted by performing data analysis, and then the average particle size (D) can be obtained therefrom by calculating 50 ) value. In addition, the average particle size can be measured using a laser diffraction method. When measuring by the laser diffraction method, specifically, after the particles to be measured are dispersed in a dispersion medium, the dispersion medium is introduced into a commercially available laser diffraction particle size measuring instrument (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of about 28 kHz at an output of about 60 W, and then the average particle size (D) based on about 50% of the particle size distribution in the measuring instrument can be calculated. 50 ).

[0034] Figure 1 1 is a conceptual diagram illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure. Figure 1 , a rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0035] The positive electrode 10 and the negative electrode 20 may be spaced and / or separated from each other (e.g., spaced apart or separated) by a separator 30 therebetween. The separator 30 may be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20, and the separator 30 may be immersed in the electrolyte ELL.

[0036] The electrolyte ELL may be a medium for transferring lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, the lithium ions may move toward the positive electrode 10 or the negative electrode 20 through the separator 30.

[0037] Positive electrode 10

[0038] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 formed on the positive electrode current collector COL1. The positive electrode active material layer AML1 may include a positive electrode active material and may further include a binder and / or a conductive material. Figure 6 and Figure 7 The positive electrode active material layer AML1 according to one or more embodiments of the present disclosure is described in more detail. An Al foil may be used as the positive electrode current collector COL1, but the present disclosure is not limited thereto.

[0039] Negative electrode 20

[0040] The negative electrode 20 for the rechargeable lithium battery can 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 can include a negative electrode active material, and can further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0041] For example, the negative electrode active material layer AML2 can include about 90 wt% to about 99.5 wt% of the negative electrode active material, about 0.5 wt% to about 5 wt% of the binder, and about 0 wt% to about 5 wt% of the conductive material.

[0042] The binder can be used to adhere the negative electrode active material particles well to each other, and also to adhere the negative electrode active material well to the negative electrode current collector COL2. The binder can include a non-aqueous binder, an aqueous binder, a dry binder, and / or a combination (e.g., any suitable combination) thereof.

[0043] The non-aqueous binder can include polyvinyl chloride, carboxylated polyvinyl chloride, polyfluoroethylene, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide imide, polyimide, and / or a combination (e.g., any suitable combination) thereof.

[0044] The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoro rubber, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and / or a combination (e.g., any suitable combination) thereof.

[0045] When the aqueous binder is used as the binder in the negative electrode active material layer AML2, a cellulose-based compound capable of imparting viscosity can be further included. The cellulose-based compound can include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and alkali metal salts thereof. The alkali metal can include Na, K, or Li.

[0046] The dry binder can be a polymer material capable of being fibrous. For example, the dry binder can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and / or a combination (e.g., any suitable combination) thereof.

[0047] Conductive materials can be used to impart electrical conductivity (e.g., electronic conductivity) to the electrodes. Any material that does not cause chemical changes (e.g., unwanted chemical changes in a rechargeable lithium battery) and that conducts electrons can be used in the battery. Non-limiting examples thereof can include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials including copper, nickel, aluminum, silver, and the like in the form of a metal powder or a metal fiber; conductive polymers such as polyphenylene derivatives; and / or mixtures thereof (e.g., any appropriate mixture).

[0048] The negative electrode current collector COL2 can include a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foam, a polymer substrate coated with a conductive metal, and / or a combination thereof (e.g., any appropriate combination thereof).

[0049] Negative electrode active material

[0050] The negative electrode active material can include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0051] The material that reversibly intercalates / deintercalates lithium ions can include a carbon-based negative electrode active material, such as, for example, crystalline carbon, amorphous carbon, and / or a combination thereof (e.g., any appropriate combination thereof). The crystalline carbon can be graphite, such as, for example, amorphous, flaky, flake-like, spherical, or fibrous natural graphite or artificial graphite. The amorphous carbon can be soft carbon, hard carbon, meso-phase pitch carbonization product, calcined coke, and the like.

[0052] The lithium metal alloy includes an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0053] The material capable of doping / dedoping lithium can be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material can include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (wherein Q is selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and / or a combination thereof (e.g., any appropriate combination thereof)). The Sn-based negative electrode active material can include Sn, SnO y (0 < y ≤ 2) (e.g., SnO2), a Sn-based alloy, and / or a combination thereof (e.g., any appropriate combination thereof).

[0054] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to one or more embodiments, the silicon-carbon composite can include silicon particles (e.g., can be in the form of silicon particles) and amorphous carbon coated on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (nuclei) in which primary silicon particles are aggregated (e.g., in the form of secondary particles) and an amorphous carbon coating (shell) on the surface of the secondary particles. The amorphous carbon can also be between the primary silicon particles, and, for example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0055] The silicon-carbon composite can further include crystalline carbon. For example, the silicon-carbon composite can include a core including crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0056] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0057] Separator 30

[0058] According to the type (kind) of the rechargeable lithium battery, a separator 30 can be present between the positive electrode 10 and the negative electrode 20. The separator 30 can include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multi-layer film of two or more layers thereof (such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, etc.).

[0059] The separator 30 can include a porous substrate and a coating on the surface (e.g., one or both surfaces (e.g., opposite surfaces)) of the porous substrate, the coating including an organic material, an inorganic material, and / or a combination (e.g., any suitable combination thereof) thereof.

[0060] The porous substrate can be a polymeric film formed of any one or two or more copolymers or mixtures thereof selected from the group consisting of polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyarylether ketones, polyetherimides, polyamideimides, polybenzimidazoles, polyether sulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfides, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon).

[0061] The organic material can include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0062] The inorganic material can include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BTiO3, Mg(OH)2, boehmite, and / or a combination thereof (e.g., any suitable combination thereof), but the present disclosure is not limited thereto.

[0063] The organic material and the inorganic material can be mixed in one coating layer, or can exist in the form of a coating layer including the organic material and a coating layer including the inorganic material stacked.

[0064] Electrolyte ELL

[0065] The electrolyte ELL for the rechargeable lithium battery can include a non-aqueous organic solvent and a lithium salt.

[0066] The non-aqueous organic solvent can be used as a medium for transporting ions participating in an electrochemical reaction of the battery.

[0067] The non-aqueous organic solvent can include a carbonate-based solvent, an ester-based solvent, an ether-based solvent, a ketone-based solvent, an alcohol-based solvent, an aprotic solvent, and / or a combination thereof (e.g., any suitable combination thereof).

[0068] The carbonate-based solvent can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc.

[0069] The ester-based solvent can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, caprolactone, etc.

[0070] The ether-based solvent can include dibutyl ether, tetraglyme, diglyme, glyme, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. In one or more embodiments, the ketone-based solvent can include cyclohexanone, etc. The alcohol-based solvent can include ethanol, isopropyl alcohol, etc., and the aprotic solvent can include: nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and can include a double bond, an aromatic ring, or an ether bond), etc.; amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolanes, etc.

[0071] The non-aqueous organic solvent can be used alone or in combination of two or more.

[0072] In one or more embodiments, if (for example, when) a carbonate-based solvent is used, cyclic carbonate and chain carbonate may be mixed and used, and may be mixed in a volume ratio of about 1:1 to about 1:9.

[0073] The lithium salt dissolved in the non-aqueous organic solvent supplies lithium ions in the battery, ensures the basic operation of the rechargeable lithium battery, and improves the transport of lithium ions between the positive electrode and the negative electrode. 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, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are integers of 1 to 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBOP) and lithium bis(oxalato)borate (LiBOB).

[0074] Rechargeable lithium battery

[0075] Rechargeable lithium batteries may be classified according to their shapes into cylindrical batteries, prismatic batteries, pouch-type batteries, coin-type (kind) batteries, and the like. Figures 2-5 are schematic diagrams each illustrating a rechargeable lithium battery according to one or more embodiments. Figure 2 A cylindrical battery is shown, Figure 3 A prismatic cell is shown, and Figure 4 and Figure 5 Shows a pouch type battery. Figures 2-5 , the rechargeable lithium battery 100 may include an electrode assembly 40 (including a separator 30 between a positive electrode 10 and a negative electrode 20) and a case 50 (including the electrode assembly 40). The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte. Figure 2 As shown in , the rechargeable lithium battery 100 may include a sealing member 60 that seals the case 50. Figure 3 In the embodiment, the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 4 and Figure 5 As shown in , the rechargeable lithium battery 100 may include electrode tabs 70 (which may be, for example, a positive electrode tab 71 and a negative electrode tab 72 ) serving as an electrical path for inducing current generated in the electrode assembly 40 to the outside.

[0076] As non-limiting examples, the rechargeable lithium battery according to one or more embodiments can be applied to a car, a mobile phone, and / or one or more appropriate types (kinds) of electronic devices.

[0077] Figure 6 and Figure 7 is a magnified view of a positive electrode active material layer of a rechargeable lithium battery according to one or more embodiments of the disclosure. Reference is made to Figure 6 and Figure 7 As previously described, the positive electrode active material layer AML1 (see Figure 1 ) can include the first particles PTC1, a conductive material CDM, and a binder BND. The plurality of first particles PTC1 can constitute a positive electrode active material according to one or more embodiments of the disclosure.

[0078] The positive electrode active material layer AML1 can further include a component that can be used as a sacrificial positive electrode.

[0079] The amount of the positive electrode active material (the first particles PTC1) in the positive electrode active material layer AML1 can be about 90 wt% to about 99 wt% with respect to 100 wt% of the positive electrode active material layer AML1. The amount of each of the binder BND and the conductive material CDM (e.g., an electronic conductor) can be about 0.5 wt% to about 5 wt% with respect to 100 wt% of the positive electrode active material layer AML1.

[0080] The binder BND can bind the first particles PTC1 and the conductive material CDM to each other. For example, the binder BND can 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, a polymer including an oxirane, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, and nylon, but one or more embodiments of the disclosure are not limited thereto.

[0081] The conductive material CDM can be used to improve the 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 the conductive material CDM, but is not limited thereto. Examples of the conductive material CDM can include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of a metal powder or a metal fiber; conductive polymers such as polyphenylene derivatives; and / or mixtures (e.g., any appropriate) thereof.

[0082] Hereinafter, the first particle PTC1 will be described in more detail.

[0083] The first particle PTC1

[0084] The first particle PTC1 can include an olivine-type lithium compound represented by Chemical Formula 1.

[0085] Chemical Formula 1

[0086] Li a1 Mn x1 Fe y1 B z1 PO 4-b1

[0087] In the above Chemical Formula 1, 0.8≤a1≤1.2, 0.45≤x1≤0.55, 0.45≤y1≤0.55, 0<z1≤0.05, 0≤b1≤0.05, and x1+y1+z1=1 can be satisfied. B can be Mg and Ti, and can be a dopant doped into the first particle PTC1. For example, 0.45

[0088] For example, the first particle PTC1 can include a compound represented by Chemical Formula 2, and can be doped with Mg and Ti:

[0089] Chemical Formula 2

[0090] Li a2 Mn x2 Fe y2 PO 4-b2

[0091] In Chemical Formula 2, 0.8≤a2≤1.2, 0.45≤x2≤0.55, 0.45≤y2≤0.55, 0≤b2≤0.05, and x2+y2=1 can be satisfied. For example, 0.45

[0092] The doping amount of B, which is the total doping amount of Mg and Ti, can be about 2500 ppm to about 5000 ppm, about 4000 ppm to about 5000 ppm, or about 4600 ppm. The doping amount of B can be defined as the weight of the doping element with respect to the total weight of the metals other than lithium (i.e., Fe, Mn, and B) in the olivine-based lithium compound represented by Chemical Formula 1 described above. That is, the doping amount of B can be the weight of the doping element with respect to the total weight of the metals excluding lithium (e.g., not including lithium) in the olivine-based lithium compound represented by Chemical Formula 1.

[0093] The doping amount of Mg can be about 1000 ppm to about 2400 ppm, or about 2400 ppm. The doping amount of Mg can be defined as the weight of the doping element (Mg) with respect to the total weight of the metals other than lithium (i.e., Fe, Mn, Mg, and Ti) in the olivine-based lithium compound represented by Chemical Formula 1 described above. That is, the doping amount of Mg can be the weight of the doping element (Mg) with respect to the total weight of the metals excluding lithium (e.g., not including lithium) in the olivine-based lithium compound represented by Chemical Formula 1 described above. For example, methods such as X-ray fluorescence analysis (XRF), energy dispersive X-ray analysis (EDX), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction analysis (XRD), nuclear magnetic resonance (NMR), etc. can be used to analyze the doping amount.

[0094] The doping amount of Ti can be about 2000 ppm. The doping amount of Ti can be defined as the weight of the doping element (Ti) with respect to the total weight of the metals other than lithium (i.e., Fe, Mn, Ti, and Mg) in the olivine-based lithium compound represented by Chemical Formula 1 described above. That is, the doping amount of Ti can be the weight of the doping element (Ti) with respect to the total weight of the metals excluding lithium (e.g., not including lithium) in the olivine-based lithium compound represented by Chemical Formula 1 described above.

[0095] The ratio of the doping amount of Mg to the doping amount of Ti (doping amount of Mg / doping amount of Ti) can be about 0.3 to about 1.2, about 0.5 to about 1.2, or about 1.2.

[0096] When the doping amounts of Mg and Ti and the ratio of the doping amount of Mg to the doping amount of Ti fall within the above-described ranges, respectively, the charge-discharge efficiency of the rechargeable lithium battery, as well as the low-temperature characteristics and the life characteristics, can be improved.

[0097] In one or more embodiments, the first particles PTC1 can include a coating on a surface thereof. The coating can cover an entire surface of the first particles PTC1, or can cover a portion of the surface of the first particles PTC1. The first particles PTC1 include a coating including carbon (e.g., carbon element). For example, the coating can include elemental carbon and / or carbon-containing compounds. The first particles PTC1 can have improved structural stability and electrical conductivity due to the coating. That is, the coating can improve the structural stability and electrical conductivity of the first particles PTC1.

[0098] The coating can further include at least one metal-containing compound selected from the group consisting of titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds. The metal-containing compounds (such as the titanium-containing compounds, the magnesium-containing compounds, and the vanadium-containing compounds) can be, for example, metal oxides, metal hydroxides, metal carbonates, or complexes or mixtures thereof. The metal-containing compounds can further include other metal or non-metal elements. For example, the metal-containing compounds can further include lithium.

[0099] The first particles PTC1 can further include carbon from (e.g., derived from) the coating described previously. The amount of carbon element in the first particles PTC1 can be about 0.5 wt% to about 10 wt%, about 1 wt% to about 3 wt%, or about 1.5 wt% to about 2.5 wt%, based on 100 wt% of the first particles PTC1.

[0100] Because the positive electrode active material according to one or more embodiments of the present disclosure includes the first particles PTC1, the mixture density, capacity, and energy density can be improved. In one or more embodiments, the mixture density of the positive electrode active material according to one or more embodiments of the present disclosure can be about 2.0 g / cc to about 2.5 g / cc, or about 2.3 g / cc to about 2.4 g / cc.

[0101] The first particles PTC1 can have a first average particle diameter. The first average particle diameter can vary according to one or more embodiments (e.g., according to one or more embodiments set forth in Figure 6 or Figure 7 embodiments set forth in

[0102] In one or more embodiments, referring back to Figure 6, the first particles PTC1 can have a single particle form. In the present specification, a single particle can refer to one particle that exists alone without a grain boundary. In terms of morphology, a single particle can refer to one particle, a monolithic structure, a single unit structure, or a non-aggregated (e.g., non-agglomerated) particle in which particles do not aggregate with each other and exist as an independent phase. For example, a single particle can be a single crystal. In one or more embodiments, the first particles can be particles containing a small amount of crystals. The single particles can be independently separated. In one or more embodiments, the first particles can be in a form in which about 2 to about 100 single particles are attached (bonded) to each other. For example, the first particles PTC1 can be provided in one or more appropriate sizes. For example, the average particle diameter of the first particles PTC1 can be about 1 μm. The minimum particle diameter of the first particles PTC1 can be about 20 nm to about 500 nm or about 200 nm to about 300 nm. For example, the minimum particle diameter can refer to a value obtained by measuring the diameters of about 30 primary particles (hereinafter, first primary particles) randomly selected from an electron micrograph of the positive electrode active material. Hereinafter, the average particle diameter of the first particles PTC1 will be described in more detail.

[0103] When the first particles PTC1 are single particles, the average particle diameter of the first particles PTC1 can be about 100 nm to about 2 μm or about 500 nm to about 2 μm. For example, the average particle diameter of the first particles PTC1 can be about 1 μm. In one or more embodiments, the average particle diameter can be measured with a particle size analyzer. The average particle diameter (D 50 ) can refer to the diameter of a particle at about 50% by volume of the cumulative volume in the particle size distribution.

[0104] In another or more embodiments, referring back to Figure 7 , the first particles PTC1 can be in a polycrystalline form, and can include secondary particles in which at least two primary particles are aggregated (e.g., agglomerated). For example, one first particle PTC1 can include a plurality of second particles PTC2 aggregated (e.g., agglomerated) with each other. The plurality of second particles PTC2 can each be a primary particle. The first particles PTC1 can have a spherical shape or an ellipsoidal shape.

[0105] In one or more embodiments, the first particles PTC1 can further include a grain boundary coating on the surface of the second particles PTC2. The grain boundary coating can exist inside the first particles PTC1. The grain boundary coating can be formed along the interface between the second particles PTC2 inside the first particles PTC1. That is, the second particles PTC2 inside the first particles PTC1 can be separated or spaced apart from each other by the grain boundary coating. For example, the grain boundary coating can refer to a layer formed by a material applied to the grain boundaries inside the first particles PTC1. The grain boundary coating can include elemental carbon and / or a carbon-containing compound. The grain boundary coating can further include at least one selected from the group consisting of a titanium-containing compound, a magnesium-containing compound, and a vanadium-containing compound.

[0106] In one or more embodiments, the first particles PTC1 can have a single particle form, which refers to a particle that exists independently without a grain boundary. Morphologically, a single particle is a monolithic structure, a single monolithic structure, or a non-aggregated particle that exists independently without aggregation. It can be a single crystal or a particle containing a small amount of crystals, and can be in a size range of about 100 nm to 2 μιη. Alternatively, the first particles PTC1 can be in a secondary particle form, which is a polycrystalline structure in which a plurality of primary particles (second particles PTC2) are aggregated. These secondary particles generally have a spherical shape or an ellipsoidal shape, and can include a grain boundary (interface) coating that separates the primary particles within the secondary particles. The grain boundary coating can include elemental carbon and / or a carbon-containing compound, and can further include at least one selected from the group consisting of a titanium-containing compound, a magnesium-containing compound, and a vanadium-containing compound, thereby enhancing structural stability and electrical conductivity of the secondary particles.

[0107] The inside of the first particles PTC1 can refer to the entire internal region of the first particles PTC1 other than the surface of the first particles PTC1. For example, the inside of the first particles PTC1 can refer to the entire internal region from a depth of about 10 nm from the outer surface of the first particles PTC1, or a region of about 10 nm depth to about 2 μιη depth. For example, in one or more embodiments, the internal region starts about 10 nm below the outer surface, and can extend to a depth of about 2 μιη.

[0108] Because the first particles PTC1 further include a grain boundary coating, structural stability can be enhanced, and the coating can be formed uniformly (e.g., substantially uniformly) on the surface of the first particles PTC1. In one or more embodiments, because the first particles PTC1 further include a grain boundary coating, electrical conductivity of the first particles PTC1 can be further improved.

[0109] The first particles PTC1 can further include carbon from (e.g., derived from) the coating and / or the grain boundary coating described above. The amount of the carbon element in the first particles PTC1 can be about 0.5 wt% to about 10 wt%, about 1 wt% to about 3 wt%, or about 1.5 wt% to about 2.5 wt%, based on a total of 100 wt% of the first particles PTC1.

[0110] When the first particles PTC1 are secondary particles, the average particle diameter of the first particles PTC1 can be about 2 μm to about 15 μm, about 3 μm to about 10 μm, or about 3 μm to about 7 μm. For example, the average particle diameter of the first particles PTC1 can be about 5 μm.

[0111] The average particle diameter of the first particles PTC1 can be greater than the average particle diameter of the second particles PTC2, which will be described in more detail later. In one or more embodiments, the average particle diameter can be measured with a particle size analyzer. The average particle diameter (D 50 ) can refer to the diameter of the particles at 50% by volume of the cumulative volume in the particle size distribution.

[0112] The second particles PTC2 can have a particle diameter of about 200 nm or less. For example, the particle diameter of the second particles PTC2 can be about 10 nm to about 200 nm, about 20 nm to about 200 nm, about 50 nm to about 200 nm, or about 100 nm to about 200 nm. In one or more embodiments, the particle diameter can refer to a value obtained by measuring the diameter of about 30 second particles PTC2 randomly selected from an electron micrograph of the positive electrode active material. The second particles PTC2 can have a substantially uniform particle diameter. The particle diameter of the second particles PTC2 can be less than the particle diameter of the first primary particles. For example, the particle diameter of the second particles PTC2 can be 100 nm less than the particle diameter of the first primary particles.

[0113] When the average particle diameters of the first particles PTC1 and the second particles PTC2 fall within the ranges described above, respectively, and the second particles PTC2 have a substantially uniform size, the rechargeable lithium battery including the positive electrode active material according to one or more embodiments of the disclosure can have improved charge-discharge capacity and low-temperature capacity.

[0114] The first particles PTC1 can have a spherical shape in which the nanosized second particles PTC2 are aggregated (e.g., agglomerated). Due to the close aggregation (e.g., agglomeration) of the second particles PTC2 with each other, the first particles PTC1 can have the following characteristics. The first particles PTC1 can have a spherical shape or an ellipsoidal shape. The average particle diameter (D 50 ) of the first particles PTC1 can be about 2 μm to about 15 μm. The first particles PTC1 can have a porosity of about 20% to about 40%. Here, the porosity (n) can be defined as the pore volume (Vp) divided by the total volume of the particles (Vt), or For example, the porosity can be measured using BELSORP (BET apparatus) of BEL JAPAN using an adsorbed gas such as nitrogen or by a method such as mercury intrusion porosimetry.

[0115] The span value obtained by analyzing the first particle PTC1 with a particle size analyzer It can be from about 0.3 to about 0.75. As used herein, the term "D 10 ” refers to the average diameter of the particles when the cumulative percentage reaches 10% by volume in the particle size distribution, and the term “D 90 ” refers to the average diameter of the particles when the cumulative percentage reaches 90% by volume in the particle size distribution.

[0116] A rechargeable lithium battery including the previously described positive electrode active material according to one or more embodiments of the present disclosure (see Figure 1 ) If (for example, when) discharged at about 0.1C in a voltage range of about 2.5V to about 4.25V, it can have an average voltage of about 3.5V to about 3.7V, or an average voltage of about 3.6V.

[0117] In addition, the rechargeable lithium battery including the positive electrode active material according to one or more embodiments of the present disclosure may have improved lifespan characteristics. For example, the capacity retention rate after 50 cycles of charge and discharge at a constant current of about 1.0C at a voltage of about 2.5V to about 4.25V may be at least about 99% or about 99.7% to about 100%.

[0118] A differential capacity (dQ / dV)-voltage charging diagram of a rechargeable lithium battery according to one or more embodiments of the present disclosure may include a first charging peak ( V1 ), a first discharging peak ( V2 ), and a second charging peak ( V3 ).

[0119] For example, the first charging peak (V1) may be at a voltage of about 3.4 V to about 4.0 V, about 3.4 V to about 3.6 V, or about 3.48 V to about 3.53 V. The first discharging peak (V2) may be at a voltage of about 3.4 V to about 4.0 V, about 3.4 V to about 3.5 V, or about 3.46 V to about 3.49 V. The second charging peak (V3) may be at a voltage of about 4.0 V to about 4.4 V, about 4.0 V to about 4.2 V, or about 4.08 V to about 4.10 V.

[0120] For example, the maximum peak voltage of the first charge peak (V1) can be at a voltage of about 3.4 V to about 3.6 V or about 3.49 V to about 3.53 V. The maximum peak voltage of the first discharge peak (V2) can be at a voltage of about 3.4 V to about 3.6 V or about 3.48 V to about 3.49 V. The maximum peak voltage of the second charge peak (V3) can be at a voltage of about 4.0 V to about 4.2 V or about 4.099 V to about 4.110 V. The maximum peak voltage can be defined as the voltage at which the peak has the highest intensity or maximum value.

[0121] The ratio (I V2 / I V1 ) of the intensity of the first discharge peak to the intensity of the first charge peak can be about 0.986 to about 0.991 or about 0.987 to about 0.990. For example, the amount of manganese (Mn) in the positive electrode active material can be about 52 mol% or less. For example, in Chemical Formula 1, x1 can be about 0.45 to about 0.52, and in Chemical Formula 2, x2 can be about 0.45 to about 0.52.

[0122] The ratio (I V3 / I V1 ) of the intensity of the second charge peak to the intensity of the first charge peak can be about 1.17 or less, or about 1.164 to about 1.166. For example, the amount of manganese (Mn) in the positive electrode active material can be about 52 mol% or less. For example, in Chemical Formula 1, x1 can be about 0.45 to about 0.52, and in Chemical Formula 2, x2 can be about 0.45 to about 0.52.

[0123] Positive electrode active material slurry

[0124] The positive electrode active material slurry according to one or more embodiments of the disclosure can include the first particles PTC1, the conductive material CDM, the binder BND, and the solvent described previously. Hereinafter, for convenience of description, the same contents as those described with reference to Figure 6 and Figure 7 will not be provided, and the differences will be mainly described in more detail.

[0125] In one or more embodiments, the positive electrode active material slurry can have a viscosity of about 7000 mPa·s or less. For example, the viscosity of the positive electrode active material slurry can be about 1000 mPa·s to about 7000 mPa·s, about 2000 mPa·s to about 6000 mPa·s, or about 3000 mPa·s to about 4000 mPa·s. When the viscosity of the positive electrode active material slurry falls within the above range, the positive electrode active material layer AML1 can be easily combined with the positive electrode current collector COL1.

[0126] For example, if (for example, when) the first particle PTC1 is a secondary particle (when), the positive electrode active material slurry according to one or more embodiments of the present disclosure may have a desired or appropriate viscosity while containing a large amount of solids. For example, the positive electrode active material slurry may contain about 60 wt% to about 70 wt% of solids. The total solid content (for example, amount) may refer to the percentage conversion value of the weight of the solid material (i.e., the dried mixture and the current collector) remaining after the solvent evaporates relative to the total weight of the current collector to which the positive electrode active material slurry is applied in the preparation of the electrode. The solid may include a positive electrode active material (first particle PTC1), a binder BND, and a conductive material CDM. When the total solid content (for example, amount) falls within the above range, the first particle PTC1 may have excellent or appropriate binding force for the positive electrode current collector COL1.

[0127] The first particle PTC1 can be connected to the positive electrode current collector COL1 (see Figure 1 ) combination, and the binder BND can increase the first particles PTC1 and the positive electrode current collector COL1 (see Figure 1 ) between them.

[0128] For example, if (for example, when) the first particle PTC1 is a single particle (when), the positive electrode active material slurry according to one or more embodiments of the present disclosure may include a large amount of binder BND in the preparation of a full battery. For example, because the first particle PTC1 has an extremely small first average particle size, the amount of binder BND in the positive electrode active material layer AML1 may be relatively large to ensure that the first particle PTC1 and the positive electrode current collector COL1 (see Figure 1 ) is within a desired or appropriate range. For example, the amount of the binder BND may be about 2 wt % to about 5 wt % or about 3 wt % to about 5 wt % relative to 100 wt % of the positive electrode active material layer AML1.

[0129] For example, if (for example, when) the first particle PTC1 is a secondary particle (when), the positive electrode active material slurry according to one or more embodiments of the present disclosure may include a small amount of binder BND in the preparation of a full battery. For example, because the first particle PTC1 has a large first average particle size, the amount of binder BND in the positive electrode active material layer AML1 may be relatively small to ensure that the first particle PTC1 and the positive electrode current collector COL1 (see Figure 1The binding force between the positive electrode active material layer AML1 and the binder BND can be within a desired or appropriate range. For example, the amount of the binder BND can be about 0.5 wt% to about 3 wt% or about 0.5 wt% to about 2 wt% with respect to 100 wt% of the positive electrode active material layer AML1. For example, in the manufacture of a full cell, if (for example, when) the first particles PTC1 are secondary particles, a smaller amount of the binder BND can be desired or required as compared to if (for example, when) the first particles PTC1 are single particles. Accordingly, the electrical resistance of the rechargeable lithium battery including the first particles PTC1 that are secondary particles can be reduced.

[0130] Method of manufacturing a positive electrode active material

[0131] Figure 8 A flowchart of a method of manufacturing a positive electrode active material according to one or more embodiments of the present disclosure is shown. Referring to FIG. 1, the method of manufacturing a positive electrode active material according to one or more embodiments of the present disclosure can include the following steps. Figure 8 The manufacturing of the first particles PTC1 according to one or more embodiments of the present disclosure will be described in more detail.

[0132] The manganese iron phosphate precursor, the lithium source, the carbon source, and the dopant source can be added to a solvent and mixed (S100). For example, the solvent can be water, ethanol, or the like.

[0133] The manganese iron phosphate precursor can be a compound containing all of manganese (Mn), iron (Fe), and phosphorus (P); a mixture of a manganese (Mn)-containing compound and an iron (Fe)- and phosphorus (P)-containing compound; and / or a mixture (e.g., any appropriate mixture) of a manganese (Mn)-containing compound, an iron (Fe)-containing compound, and a phosphorus (P)-containing compound. For example, the manganese iron phosphate precursor can include Mn x Fe 1-x PO4·H2O; a mixture of MnCO3and FePO4·H2O; and / or a mixture (e.g., any appropriate mixture) of MnCO3, FeSO4, and H3PO4. Here, x can be about 0.2 to about 0.8 (e.g., about 0.45 to about 0.55).

[0134] The lithium source can 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, lithium hydrogen phosphate, lithium dihydrogen phosphate, and lithium citrate.

[0135] The carbon source can include at least one selected from the group consisting of glucose, sucrose, fructose, cellulose, starch, citric acid, polyacrylic acid, polyethylene glycol, and dopamine.

[0136] The dopant source can include an oxide containing a dopant metal and / or a chloride containing a dopant metal. For example, the dopant source can include at least one selected from the group consisting of the Mg-containing oxide, the Mg-containing chloride, the Ti-containing oxide, and the Ti-containing chloride in Chemical Formula 1 above. For example, the dopant source can include at least one of the Mg-containing oxide and the Mg-containing chloride, and at least one of the Ti-containing oxide and the Ti-containing chloride.

[0137] The mixture can be wet-milled (S200). For the milling, a proper wet mill capable of controlling temperature can be used. In particular, at least one selected from a bead mill, a ball mill, a mortar mill, an apex mill, a super mill, and a basket mill can be used for the wet milling. Through the wet milling process, the particles in the mixture can be milled to a fine size.

[0138] According to one or more embodiments of the present disclosure, the wet milling (S200) can also not be provided. In particular, in order to maximize or increase the average particle size of the finally prepared first particles PTC1, the wet milling (S200) of the mixture can also not be provided.

[0139] The solvent can be removed from the mixture to form a dried mixture (S300).

[0140] When the first particles PTC1 in Equation 1 above are prepared, according to one or more embodiments of the present disclosure, forming the dried mixture can include directly evaporating the mixture. For example, the direct evaporation can include static drying or spray drying. Figure 6 When the first particles PTC1 in Equation 1 above are prepared, according to one or more embodiments of the present disclosure, forming the dried mixture can include directly evaporating the mixture. For example, the direct evaporation can include static drying or spray drying.

[0141] Figure 7 When the first particles PTC1 in Equation 1 above are prepared, according to another one or more embodiments of the present disclosure, forming the dried mixture can include spray drying the mixture. A generally used spray drying apparatus can be used for the spray drying. For example, the spray drying can be performed by using at least one selected from an ultrasonic spray drying apparatus, an air nozzle spray drying apparatus, an ultrasonic nozzle spray drying apparatus, a filter expansion droplet generation apparatus, and an electrostatic spray drying apparatus.

[0142] The particles finely reduced in size to the primary particles after the wet milling process can be aggregated (e.g., agglomerated) with each other through the spray drying process, thereby forming secondary particles. Therefore, by adjusting the flow rate and flow rate of the carrier gas, the temperature, the residence time in the reactor, the internal pressure, etc. during the spray drying process, the first particles PTC1 can be formed as secondary particles of a desired or proper size.

[0143] ​In one or more embodiments, the mixture to be spray-dried can have a total solid content (e.g., amount) (TSC) of about 20 wt% to about 40 wt%. The total solid content (e.g., amount) can refer to a percentage converted value of the weight of the solid material remaining after solvent evaporation (i.e., the dried mixture) relative to the total weight of the mixture (i.e., the spray liquid). For example, the spray liquid can have a total solid content (e.g., amount) of about 30 wt%.

[0144] When the total solid content (e.g., amount) is less than about 20 wt%, there can be a disadvantage of a decrease in the average particle size of the first particles PTC1 and a decrease in the yield. When the total solid content (e.g., amount) is greater than about 40 wt%, it can become difficult to adjust the average particle size of the first particles PTC1, and the size difference between the first particles PTC1 can increase.

[0145] At the total solid content (e.g., amount) mentioned above, the spray liquid according to the present embodiment can have a viscosity of about 1500 mPa-s to about 2500 mPa-s. For example, the spray liquid can have a viscosity of about 2000 mPa-s.

[0146] In one or more embodiments, the input rate of the spray-drying can be about 0.1 kg / min to about 0.9 kg / min. The input rate of the spray-drying can be defined as the weight of the solvent and the raw material mixture added per minute. In one or more embodiments, the input rate of the spray-drying according to one or more embodiments of the present disclosure can be about 0.5 kg / min.

[0147] In one or more embodiments, the spray-drying can be performed at a temperature of about 100°C to about 300°C. For example, the spray-drying can be performed at a temperature of about 200°C to about 300°C, at a temperature higher than about 200°C and lower than or equal to about 300°C, or at a temperature of about 230°C to about 270°C. The spray gas (e.g., air) used for the spray-drying can be injected at a first temperature and discharged at a second temperature. For example, the first temperature can be about 200°C to about 250°C. The second temperature can be about 80°C to about 150°C.

[0148] The spray liquid can have an input pressure of about 0.3 MPa to about 0.7 MPa. For example, the input pressure of the spray liquid can be about 0.5 MPa.

[0149] When the input rate, the input pressure, and the temperature of the spray-drying fall within the above-mentioned ranges, respectively, the first particles PTC1 can have a spherical shape and a desired or appropriate porosity.

[0150] The spray liquid used for spray drying can have a flow rate of about 30 mL / min to about 80 mL / min. A flow rate less than about 30 mL / min may result in nozzle clogging, reduced yield, and other disadvantages. A flow rate greater than about 80 mL / min may prevent the mixture from being completely dried due to condensation of water in the spray drying apparatus. The spray liquid can have an input pressure of about 0.3 MPa to about 0.7 MPa. For example, the input pressure of the spray liquid can be about 0.5 MPa.

[0151] The dried mixture may be calcined in an inert atmosphere (S400). The inert atmosphere may be a nitrogen atmosphere and / or an argon atmosphere. The calcination process may be performed at a temperature of about 500°C to about 1000°C or about 600°C to about 800°C. The calcination process may be performed for about 4 hours to about 20 hours or about 6 hours to about 12 hours. When the dried mixture is calcined, first particles PTC1 containing the compound represented by Chemical Formula 1 described previously may be formed.

[0152] The calcined first particles PTC1 may be dry-milled ( S500 ). The calcined mixture may be milled using a jet mill or the like.

[0153] In preparation Figure 6 When the first particles PTC1 in the calcined mixture are prepared, according to one or more embodiments of the present disclosure, the calcined mixture may be ground at a rotation speed of at least about 7000 rpm. For example, the calcined mixture may be ground at a rotation speed of about 7000 rpm to about 10000 rpm or about 7500 rpm to about 9000 rpm. Accordingly, the first particles PTC1 may have a particle size as follows: Figure 6 The form of a single particle is illustrated in FIG.

[0154] In preparation Figure 7 When the first particle PTC1 in the calcined mixture is prepared, according to one or more embodiments of the present disclosure, the calcined mixture may be ground at a rotation speed of about 0 rpm to about 7000 rpm. For example, the calcined mixture may be ground at a rotation speed of about 4000 rpm to about 7000 rpm, about 4000 rpm to about 6000 rpm, or about 4500 rpm to about 5000 rpm. Figure 6 The preparation of the active material of the positive electrode is different, and the dry grinding (S500) after calcination can be carried out under relatively mild conditions. Figure 7 When the positive electrode active material in the dry milling (S500) is used, for example, dry milling (S500) may not be performed. When the rotation speed in the dry milling (S500) falls within the above-mentioned range, the first particles PTC1 may remain in the form of secondary particles. Accordingly, the first particles PTC1 may have the following characteristics: Figure 7 The form of the secondary particles is explained in .

[0155] In preparation Figure 7In the first particle PTC1, according to one or more embodiments of the present disclosure, a carbon source can be introduced into the manganese iron phosphate precursor to form a carbon coating uniformly (e.g., substantially uniformly) on the surface of the primary particles. Thereafter, the primary particles can be closely aggregated (e.g., agglomerated) by spray drying to form dense spherical secondary particles. As a result, the first particle PTC1 can include a stable carbon coating on the outside and inside of the first particle PTC1, and thus can have a relatively high carbon content (e.g., amount). Due to the high carbon content (e.g., amount) of the first particle PTC1, Figure 7 Due to the high carbon content (e.g., amount) of the first particle PTC1, the positive electrode active material layer AML1 can have improved electrical conductivity.

[0156] The carbon element according to one or more embodiments of the present disclosure can be analyzed using an Elementar Micro Cube elemental analyzer. The specific method of operation and conditions are as follows. About 1 mg to 2 mg of a sample is weighed in a tin cup, placed in an automatic sampling tray, and introduced into a combustion tube through a ball valve, and combustion is performed at a combustion temperature of about 1000°C. Subsequently, the combustion gas is reduced using a reduced copper to form carbon dioxide. The carbon dioxide is detected using a thermal conductivity detector (TCD).

[0157] According to one or more embodiments of the present disclosure, scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) and quantitative analysis are performed on the surface of the particles to measure the carbon content (e.g., amount). In addition to SEM-EDS, inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectrometry (ICP-OES), etc. can be used to measure the carbon content (e.g., amount).

[0158] Hereinafter, the present disclosure will be described in greater detail with reference to examples. However, the following examples are given only to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.

[0159] Example 1: Preparation of a first particle in a single particle form

[0160] A manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added to water in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1:1.03:0.01:0.004. To the mixture, 10 wt% of glucose was further added. The mixture was wet-milled by ball milling. The mixture was dried by evaporation through heating on a tray, and then dried in a vacuum oven at about 85°C for about 4 hours. The dried mixture was calcined at about 650°C for about 10 hours in a nitrogen atmosphere. The calcined product was ground at a rotation speed of about 8000 rpm to obtain a first particle in a single particle form. The chemical formula of the first particle was about LiMn0.5 Fe 0.5 PO4, Mg, and Ti at about 2400 ppm and about 2000 ppm, respectively.

[0161] Example 2: Preparation of first particles in the form of secondary particles

[0162] A manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were mixed in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.01 :0.004 in water with 10 wt% glucose added. The mixture was dried by evaporation through spray drying at an input pressure (spray pressure) of about 0.5 MPa and a temperature of about 230 °C. The dried mixture was calcined in a nitrogen atmosphere at about 650 °C for about 10 hours to obtain first particles in the form of single particles. The first particles had a chemical formula of LiMn 0.5 Fe 0.5 PO4, Mg, and Ti at about 2400 ppm and about 2000 ppm, respectively.

[0163] In other words, Example 1 describes the preparation of single particles, while Example 2 describes in detail the preparation of secondary particles, both having the same chemical composition but different processing methods. In Example 1, a manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were mixed in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.01 :0.004 in water with 10 wt% glucose added. The mixture was dried by evaporation through spray drying at an input pressure (spray pressure) of about 0.5 MPa and a temperature of about 230 °C. The dried mixture was calcined in a nitrogen atmosphere at about 650 °C for about 10 hours to obtain first particles in the form of single particles. The first particles had a chemical formula of LiMn 0.5 Fe 0.5 PO4, Mg, and Ti at about 2400 ppm and about 2000 ppm, respectively.

[0164] Comparative Example 1: Preparation of first particles in the form of single particles

[0165] A first particle was prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.6 Fe 0.4 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.0025:0.004, the first particle had a chemical formula of about LiMn 0.6 Fe 0.4 PO4, and the doping amount of Mg was about 600 ppm.

[0166] Comparative Example 2: Preparation of a first particle in a single particle form

[0167] A first particle was prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.55 Fe 0.45 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.0025:0.004, the first particle had a chemical formula of about LiMn 0.55 Fe 0.45 PO4, and the doping amount of Mg was about 600 ppm.

[0168] Comparative Example 3: Preparation of a first particle in a single particle form

[0169] A first particle was prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.0025:0.004, the first particle had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and the doping amount of Mg was about 600 ppm.

[0170] Comparative Example 4: Preparation of a first particle in a single particle form

[0171] A first particle was prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.45 Fe 0.55 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.0025:0.004, the first particle had a chemical formula of about LiMn 0.45 Fe 0.55 PO4, and the doping amount of Mg was about 600 ppm.

[0172] Comparative Example 5: Preparation of first particles in single particle form

[0173] First particles were prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.4 Fe 0.6 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.0025:0.004, the first particles had a chemical formula of about LiMn 0.4 Fe 0.6 PO4, and the doping amount of Mg was about 600 ppm.

[0174] Comparative Example 6: Preparation of first particles in single particle form

[0175] First particles were prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4) and lithium carbonate were added in a molar ratio of (Mn+Fe):Li of about 1 : 1.03, and the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4.

[0176] Comparative Example 7: Preparation of first particles in single particle form

[0177] First particles were prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, and magnesium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg of about 1 : 1.03:0.0025, the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and the doping amount of Mg was about 600 ppm.

[0178] Comparative Example 8: Preparation of first particles in single particle form

[0179] First particles were prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Ti of about 1 : 1.03:0.004, the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and the doping amount of Ti was about 2000 ppm.

[0180] Comparative Example 9: Preparation of first particles in single particle form

[0181] First particles were prepared in substantially the same manner as Example 1, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1 : 1.03:0.02:0.004, and the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and a doping amount of Mg of about 4800 ppm.

[0182] Comparative Example 10: Preparation of first particles in secondary particle form

[0183] First particles were prepared in substantially the same manner as Example 2, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4) and lithium carbonate were added in a molar ratio of (Mn+Fe):Li of about 1 : 1.03, and the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4.

[0184] Comparative Example 11 : Preparation of first particles in secondary particle form

[0185] First particles were prepared in substantially the same manner as Example 2, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, and magnesium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg of about 1 : 1.03:0.0025, and the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and a doping amount of Mg of about 600 ppm.

[0186] Comparative Example 12: Preparation of first particles in secondary particle form

[0187] First particles were prepared in substantially the same manner as Example 2, except that manganese iron phosphate precursor (Mn 0.5 Fe 0.5 PO4), lithium carbonate, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Ti of about 1 : 1.03:0.004, and the first particles had a chemical formula of about LiMn 0.5 Fe 0.5 PO4, and a doping amount of Ti of about 2000 ppm.

[0188] Preparation of first particles in the form of secondary particles

[0189] The first particles were prepared in substantially the same manner as in Example 2, except that manganese iron phosphate precursor (Mn 0.4 Fe 0.6 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1:1.03:0.01:0.004.

[0190] Preparation of first particles in the form of secondary particles

[0191] The first particles were prepared in substantially the same manner as in Example 2, except that manganese iron phosphate precursor (Mn 0.6 Fe 0.4 PO4), lithium carbonate, magnesium dioxide, and titanium dioxide were added in a molar ratio of (Mn+Fe):Li:Mg:Ti of about 1:1.03:0.01:0.004.

[0192] Preparation of positive electrode

[0193] A positive electrode active material slurry was prepared by mixing 95 wt% of the final positive electrode active material, 3 wt% of a polyvinylidene fluoride binder, and 2 wt% of a carbon black conductive material in an N-methylpyrrolidone solvent. The positive electrode active material slurry was applied to an aluminum current collector and dried, and then roll-pressed, to prepare a positive electrode.

[0194] Manufacture of rechargeable lithium battery

[0195] The prepared positive electrode and a lithium metal counter electrode as a counter electrode were used to prepare a 2032 type (kind) coin half cell. A separator (thickness: about 16 µm) formed of a porous polyethylene (PE) film was interposed between the positive electrode and the lithium metal counter electrode, and an electrolyte was introduced, to manufacture a rechargeable lithium battery. As the electrolyte, an electrolyte obtained by mixing 1.3 M of LiPF6in a mixed solvent containing ethylene carbonate (EC), ethylmethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:4:3 was used.

[0196] Table 1

[0197]

[0198]

[0199] Evaluation Example 1: Surface analysis of positive electrode active material

[0200] Figure 9 A scanning electron microscope (SEM) image of the first particles prepared according to Example 1 is shown.Figure 10 An SEM image of the first particles prepared according to Example 2 is shown. Figure 11 An SEM image of the first particles prepared according to Comparative Example 1 is shown.

[0201] Reference is made to Figure 9 and Figure 11 It can be seen that the first particles according to Example 1 and Comparative Example 1 of the present disclosure are in the form of fine, single particles. Reference is made to Figure 10 It can be seen that the first particles according to Example 2 of the present disclosure are in the form of spherical secondary particles in which a plurality of primary particles are aggregated (e.g., agglomerated). It can be seen that the second particles PTC2 (see Figure 7 ) according to Example 2 of the present disclosure are in the form of fine, nanometer-sized, single particles (primary particles). In one or more embodiments, reference is made to Figure 9 and Figure 10 The primary particles according to Example 2 (second particles PTC2 (see Figure 7 )) are smaller than the primary particles according to Example 1, and are substantially uniform.

[0202] Evaluation Example 2: Evaluation of Active Material

[0203] The powder density (PD) of the positive electrode active materials according to Example 1 and Example 2, and Comparative Examples 1-14 was measured, and the results are listed in Table 2.

[0204] Table 2

[0205] Classification Powder Compacted Density (g / cc) Example 1 2.33 Example 2 2.34 Comparative Example 1 2.35 Comparative Example 2 2.34 Comparative Example 3 2.36 Comparative Example 4 2.32 Comparative Example 5 2.35 Comparative Example 6 2.35 Comparative Example 7 2.36 Comparative Example 8 2.34 Comparative Example 9 2.35 Comparative Example 10 2.36 Comparative Example 11 2.33 Comparative Example 12 2.34 Comparative Example 13 2.35 Comparative Example 14 2.36

[0206] Evaluation Example 3: Evaluation of Differential Capacity

[0207] The differential capacity of rechargeable lithium batteries prepared using the positive electrode active materials according to Example 1 and Example 2, and Comparative Examples 4, 5, and 13 was evaluated. The rechargeable lithium batteries were charged and discharged once at about 0.2C, and then the charging and discharging cycles were repeated twice in substantially the same manner. The results are shown in Table 3 and Figure 12 .

[0208] The respective values of the maximum peak voltages (V max,V1 , V max,V2 , and V max,V3 ) of the first charge peak (V1), the first discharge peak (V2), and the second charge peak (V3), and the ratios of the peak intensities (I V2 / I V1 , and I V3 / I V1 ) are listed in Table 3. Figure 12A graph showing the differential capacity (dQ / dV)-voltage charge curves measured once according to Example 1 and Comparative Example 1.

[0209] Table 3

[0210]

[0211]

[0212] Referring to Table 3 and Figure 12 , according to Example 1 and Example 2, unlike Comparative Example 4, Comparative Example 5, and Comparative Example 13, the maximum peak voltage (V max,V1 , V max,V2 , and V max,V3 ) was observed within the above range, and the ratio of peak intensities (I V2 / I V1 , and I V3 / I V1 ) fell within the above range.

[0213] Evaluation Example 4: Evaluation of battery characteristics

[0214] The characteristics of rechargeable lithium batteries prepared using the positive electrode active material according to Example 1 and Example 2, and Comparative Examples 1 to 14 were evaluated.

[0215] For initial charge and discharge, the rechargeable lithium battery was initially charged at 25°C under conditions of constant current (0.1C) and constant voltage (4.25V) (cut-off 0.05C), rested for about 10 minutes, and then discharged at constant current (0.1C) until the voltage reached 2.5V. And the initial discharge capacity and the initial charge capacity were measured. The "efficiency (%)” was expressed as the initial discharge capacity / initial charge capacity. The average voltage was obtained by integrating the area under the discharge voltage curve (voltage-capacity graph) after the initial charge and discharge of the battery cell, and then dividing the integral by the discharge capacity. The battery cell was charged and discharged at 0.2C / 0.2C rate in the voltage range of 3.0V~4.25V at 25°C to calculate the energy density. The energy density was obtained by using the calculation formula {average driving voltage (V) x capacity (Ah) / battery cell weight (kg)}, in which the capacity was calculated by multiplying the positive electrode weight (g) and the discharge capacity (mAh / g). Thereafter, the charge and discharge cycle was repeated 50 times under conditions of about -20°C, about 1.0C (4.25V, cut-off 0.05C) / 1.0C (2.5V). The "life span (%) at 50 cycles” was expressed as the discharge capacity after the 50th cycle / initial discharge capacity. And, in addition, the rechargeable lithium battery was manufactured, and the battery was initially charged at about 25°C under conditions of constant current of 0.1C and constant voltage (4.25V) (cut-off 0.05C), rested for 10 minutes, and then discharged at constant current of 0.1C until 2.5V, and then, at about -20°C, the battery was additionally charged under conditions of constant current of 0.1C and constant voltage (4.25V) (cut-off 0.05C), rested for 10 minutes, and then discharged at constant current of 0.1C until 2.5V, to measure the initial discharge capacity at about -20°C. The results of evaluating the battery characteristics are listed in Table 4.

[0216] Table 4

[0217]

[0218]

[0219] Referring to Table 4, it can be seen that the rechargeable lithium batteries according to Example 1 and Example 2 have high average voltage and excellent or appropriate life span characteristics. In particular, it can be seen that the rechargeable lithium battery according to Example 1 of the present disclosure has similar / higher average voltage and longer life span than the rechargeable lithium batteries according to Comparative Examples 1~9. It can be seen that the rechargeable lithium battery according to Example 2 of the present disclosure has similar / higher average voltage and longer life span than the rechargeable lithium batteries according to Comparative Examples 10~14.

[0220] In one or more embodiments, the rechargeable lithium battery according to Example 2 has a longer lifespan than the rechargeable lithium battery according to Example 1. In addition, it can be seen that the rechargeable lithium battery according to Example 2 has a higher initial charge capacity than the rechargeable lithium battery according to Example 1, so the rechargeable lithium battery according to Example 2 has a lower resistance.

[0221] The positive electrode active material according to one or more embodiments of the present disclosure can have improved mixture density (tap density, powder compaction density) as well as improved capacity and energy density. The positive electrode active material layer according to one or more embodiments of the present disclosure can be easily combined with a positive electrode current collector with a relatively small amount of binder. The rechargeable lithium battery according to one or more embodiments of the present disclosure can have a relatively high average voltage, charge-discharge capacity, efficiency, and energy density, and has excellent or appropriate lifespan characteristics (capacity retention rate).

[0222] A person of ordinary skill in the art will recognize, in light of the overall content of the present disclosure, that each appropriate feature of the various embodiments of the present disclosure can be combined, in part or in whole, with each other, and can be technically interlocked and operated in various appropriate manners, and each embodiment can be implemented independently of each other or in combination with each other in any appropriate manner, unless otherwise recited or implied.

[0223] In the context of the present application, and unless otherwise limited, the terms "use," "using," and "used" can be considered synonymous with the terms "utilize," "utilizing," and "utilized," respectively.

[0224] Further, when describing embodiments of the inventive concept, the use of "may" indicates that one or more embodiments of the inventive concept. Also, the term "exemplary" is intended to indicate an example or an illustration.

[0225] As used in the specification and claims, the singular forms "a," "an" and "the" include plural references unless the context clearly dictates otherwise.

[0226] The battery manufacturing apparatus, battery management system (BMS) apparatus, and / or any other related apparatus or components according to the embodiments of the present application described herein can be implemented with any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, various components of the apparatus can be formed on one integrated circuit (IC) chip or on separate IC chips. Further, various components of the apparatus can be implemented on a flexible printed circuit film, tape carrier package (TCP), or printed circuit board (PCB), or formed on one substrate. Further, various components of the apparatus can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functions described herein. The computer program instructions are stored in a memory which can be implemented in a 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, for example, CD-ROM, flash drive, etc. Also, a person of ordinary skill in the art should recognize that the functionality of various computing devices can be combined or integrated into a single computing device, or the functionality of a particular computing device can be distributed across one or more other computing devices, without departing from the scope of the present disclosure.

[0227] While one or more embodiments of the present disclosure have been described with reference to the attached figures, it is to be understood that the present disclosure is not limited to these embodiments, and that one or more appropriate changes and modifications can be made by a person of ordinary skill in the art within the spirit and scope of the claimed disclosure. Therefore, the above one or more embodiments should be understood in all aspects as illustrative and not restrictive.

Claims

1. A positive electrode active material comprising first particles, the first particles comprising a compound represented by Chemical Formula 1, and having a first average particle diameter: Chemical Formula 1 Li a1 Mn x1 Fe y1 B z1 PO 4-b1 , wherein in Chemical Formula 1, 0.8 ≤ a1 ≤ 1.2, 0.45 ≤ x1 ≤ 0.55, 0.45 ≤ y1 ≤ 0.55, 0 < z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1, and B is Mg and Ti. 2.The positive electrode active material of claim 1, wherein B is a dopant, and wherein a ratio of a doping amount of Mg to a doping amount of Ti is 0.5 to 1.

2. 3.The positive electrode active material of claim 1, wherein the first particles comprise a coating layer containing a carbon element, and an amount of the carbon element in the first particles is 0.5 wt% to 10 wt% based on the first particles totaling 100 wt%. 4.The positive electrode active material of claim 1, wherein the first particles are single particles, and the first average particle diameter of the first particles is 100 nm to 2 μm. 5.The positive electrode active material of claim 1, wherein the first particles comprise a plurality of second particles aggregated with each other, the first average particle diameter of the first particles is 2 μm to 15 μm, and each of the plurality of second particles is a primary particle, and has a particle diameter of 200 nm or less. 6.The positive electrode active material of claim 5, wherein the first particles have a porosity of 20% to 40%. 7.The positive electrode active material of claim 5, wherein a span value obtained by analyzing the first particles with a particle size analyzer is 0.3 to 0.

75. 8.A positive electrode active material comprising first particles, the first particles comprising a compound represented by Chemical Formula 2, and having a first average particle diameter, wherein the first particles are doped with Mg and Ti, wherein a total doping amount of Mg and Ti is 2500 ppm to 5000 ppm: Chemical Formula 2 Li a2 Mn x2 Fe y2 PO 4-b2 and wherein, in Chemical Formula 2, 0.8 ≤ a2 ≤ 1.2, 0.45 ≤ x2 ≤ 0.55, 0.45 ≤ y2 ≤ 0.55, 0 ≤ b2 ≤ 0.05, and x2 + y2 = 1. 9.The positive electrode active material of claim 8, wherein a doping amount of Mg is 1000 ppm to 2400 ppm. 10.The positive electrode active material of claim 8, wherein a doping amount of Ti is 2000 ppm. 11.The positive electrode active material of claim 8, wherein a ratio of a doping amount of Mg to a doping amount of Ti is 0.5 to 1.

2. 12.The positive electrode active material of claim 8, wherein the first particles comprise a coating layer containing a carbon element, and an amount of the carbon element in the first particles is 0.5 wt% to 10 wt% based on the first particles totaling 100 wt%. 13.The positive electrode active material of claim 8, wherein the first particles are single particles, and the first average particle diameter of the first particles is 100 nm to 2 μm. 14.The positive electrode active material of claim 8, wherein the first particles include a plurality of second particles aggregated with each other, the first average particle diameter of the first particles is 2 μm to 15 μm, and each of the plurality of second particles is a primary particle and has a particle diameter of 200 nm or less.

15. A rechargeable lithium battery comprising: a positive electrode including a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, the positive electrode active material layer including the positive electrode active material according to any one of claims 1 to 14; 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, wherein a differential capacity dQ / dV-voltage charge profile of the rechargeable lithium battery includes a first charge peak V1 at a voltage of 3.4 V to 4.0 V, a first discharge peak V2 at a voltage of 3.4 V to 4.0 V, and a second charge peak V3 at a voltage of 4.0 V to 4.4 V.

16. The rechargeable lithium battery of claim 15, wherein the ratio of the intensity of the first discharge peak to the intensity of the first charge peak I V2 / I V1 is 0.986 to 0.

991.

17. The rechargeable lithium battery of claim 15, wherein the ratio of the intensity of the second charge peak to the intensity of the first charge peak I V3 / I V1 is 1.17 or less.

18. The rechargeable lithium battery according to claim 15, wherein an average voltage is 3.5 V to 3.7 V when discharged at 0.1 C at a voltage of 2.5 V to 4.25 V.

19. The rechargeable lithium battery according to claim 15, wherein a capacity retention rate after 50 cycles of charging and discharging at a constant current of 1.0 C at a voltage of 2.5 V to 4.25 V is at least 99%.

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